PAGENO="0001" 0! 02 ~ HYDROGEN HEARINGS BEFORE THE SUBCOMMITTEE ON ENERGY RESEARCH, DEVELOPMENT AND DEMONSTRATION OF THE COMMITTEE ON SCIENCE AND TECHNOLOGY U.S. HOUSE OF REPRESENTATIVES NINETY-FOURTH CONGRESS FIRST SESSION JUNE 10 AND 12, 1975 [No. 29] Printed for the use of the Committee on Science and Technology 0 ~ U.S. GOVERNMENT PRINTING OFFICE 62-3320 WASHINGTON : 1975 PAGENO="0002" COMMITTEE ON SCIENCE AND TECHNOLOGY OLIN E. TEAGUE, Texas, Chairman KEN HECHLER, West Virginia THOMAS N. DOWNING, Virginia DON FUQUA, Florida JAMES W. SYMINGTON, Missouri WALTER FLOWERS, Alabama ROBERT A. ROE, New Jersey MIKE McCORMACK, Washington GEORGE E. BROWN, JR., California DALE MILFORD, Texas RAY THORNTON, Arkansas JAMES H. SCHEUER, New York RICHARD L. OTTINGER, New York HENRY A. WAXMAN, California PHILIP II. HAYES, Indiana TOM HARKIN, Iowa JIM LLOYD, California JEROME A. AMBRO. New York CHRISTOPHER J. DODD, Connecticut MICHAEL T. BLOUIN, Iowa TIM L. HALL, Illinois ROBERT (BOB) KRUEGER, Texas MARILYN LLOYD, Tennessee JAMES J. BLANCHARD, Michigan TIMOTHY E. WIRTH, Colorado KEN HECHLER, West Virginia DON FUQUA, Florida JAMES W. SYMINGTON, Missouri GEORGE E. BROWN, JIL, California RAY THORNTON, Arkansas RICHARD L. OTTINGER, New York HENRY A. WAXMAN, California PHILIP H. HAYES, Indiana TOM HARKIN, Iowa JEROME A. AMBRO, New York CHRISTOPHER J. DODD, Connecticut ROBERT (BOB) KRUEGER, Texas MARILYN LLOYD, Tennessee JAMES J. BLANCHARD, Michigan TIMOTHY E. WIRTH, Colorado CHARLES A. MOS~ER, Ohio ALPHONZO BELL, California JOHN JARMAN, Oklahoma JOHN W. WYDLER, New York LARRY WINN, Ja.. Kansas LOUIS FREY, Ja., Florida BARRY M. GOLDWATER, JR., California MARVIN L. ESCH, Michigan JOHN B. CONLAN, Arizona GARY A. MYERS, Pennsylvania DAVID F. EMERY, Maine LARRY PRESSLER, South Dakota BARRY XI. GOLDWATER, Ja., California ALPHONZO BELL, California JOHN W. WYDLER, New York LARRY WINN, JR., Kansas LOUIS FREY, JR., Florida MARVIN L. ESCH, Michigan JOHN B. `CONLAN, Arizona JOHN L. SWIGERT, Jr., Executive Director HAROLD A. `GoULD, Deputy Director PHILIP B. YEAGER, Counsel FRANK R. HAMMILL. Jr., Counsel JAMES E. WILsON, Technical Consultant J. THOMAS RATCHFORD, yczencc Consultant JOHN D. HOLMFELD, Jcience Consultant RALPH N. READ, Technical Consultant ROBERT C. KETCHAM, Counsel REGINA A. DAVIS, Clerk CARL SWARTZ, Minority Staff SUBCOMMITTEE ON ENERGY RESEARCH, DEVELOPMENT AND DEMONSTRATION MIKE McCORMACK, Washington, Chairman (II) PAGENO="0003" CONTENTS WITNESSES June 10, 1975: Dr. James S. Kane, Deputy Assistant Administrator for Conservation, Energy Research and Development Administration; accompanied by Dr. Jack Yanderryn, Assistant Director for Energy Storage, Office of the Assistant Administrator for Conservation, Energy Research and Development Administration, and Dr. Ray Zahradnik, Acting Director, Division of Coal Conversion and Utilization in Fossil ~`age Energy, Energy Research and Development Administration 18 Dr. Harrison H. Schmitt, Assistant Administrator for Energy Pro- grams, National Aeronautics and Space Administration, accom- panied by Mr. R. D. Ginter, Director, Energy Systems Division, Office of Energy Programs, National Aeronautics and Space Administration 34 Dr. James E. Funk, Dean, College of Engineering, University of Kentucky 42 June 12, 1975: Commander Paul Petzrick, Director, Navy Energy, Research and De- velopment Office, Headquarters, Naval Materiel Command, accom- panied by Dr. Peter Waterman, Special Assistant, Office of the Assistant Secretary of the Navy, Research and Development, and Mr. Homer Carhart, Naval Research Laboratory and Mr. Carl Hershner, Naval Ship Research and Development Center 51 Dr. Derek P. Gregory, Director, Energy Systems Research, Institute of Gas Technology 61 Mr. Sidney H. Law, Director of Research, Northeast Utilities, accom- panied by Mr. Michael Lotker, Scientist, Advanced Energy Con- version, Northeast Utilities 167 APPENDIX I ADDITIONAL STATEMENTS FOR THE RECORD Mr. G. Daniel Brewer, manager, hydrogen studies, Lockheed-California Co. 227 Mr. John A. Casazza, vice president, planning and research, Public Service Electric & Gas Co 263 Dr. Edward M. Dickson, manager, resources program, Operations Evalua- tion Department, Stanford Research Institute 273 Mr. William J. D. Escher, Escher Technology Associates 576 Mr. John B. Johnson, associate manager, Feedstock & Energy Policy Office, Union Carbide Corp 583 Dr. Fritz R. Kaihammer, Manager, Electrochemical Energy Conversion & Storage, Electric Power Research Institute 585 Dr. Ram Manvi, school of engineering, California State University of Los Angeles 587 Dr. John W. Michel, Technical Assistant for Advanced Energy Systems, Oak Ridge National Laboratory 597 Mr. Harvey A. Proctor, chairman of the board, Southern California Gas Co. 614 Mr. F. J. Saizano, Project Engineer for Hydrogen Storage and Production, and Mr. Kenneth C. Hoffman, Head, Engineering and Systems Division, Brookhaven National Laboratory 638 Dr. James H. Swisher, supervisor, Exploratory Materials Division, Sandia Laboratories 642 Dr. Robert H. Wentorf, Jr., General Electric Co., Research and Develop- ment Center 643 (III) PAGENO="0004" Iv APPENDIX II ADDITIONAL MATERIAL FOR THE RECORD "Hydrogen As a Navy Fuel," XRL Report 7754, Homer W. Carh'art, Wilbur A. Affens, Bruce D. Boss, Robert N. Hazlett, and Sigmund Schuldiner, Page Naval Research Laboratory 673 "Hydrogen As a Fuel," R. F. McAlevy, III, R. B. Cole, J. W. Hollenberg, L. Kurylko, R. S. Magee, K. H. Weil, Stevens Institute of Technology__ 713 "Alternative, Synthetically Fueled, Navy Systems: Force Element Missions and Technology," B. Berkowitz, J. DeVore, S. Harris, L. Haun, W. Mc- Namara and W. Slager, General Electric Co., TEMPO, Center for Ad- vanced Studies 953 "The Hydrogen Economy," George N. Chatham and Migdon R. Segal, Science Policy Research Division, Congressional Research Service 1074 "Thermochemical Hydrogen Generation: Heat Requirements and Costs," R. Shinnar, Science 1104 "Hydrogen: A Versatile Element," C. E. Bamberger and J. Braunstein, American Scientist 1107 "Cryogenic H2 and National Energy Needs," J. Hord, Cryogenic Engineering Conference 1119 "Research Opportunities in Cryogenic Hydrogen-Energy Systems," J. Hord, Hydrogen Energy Fundamentals Symposium Course 1142 "Selected Topics on Hydrogen Fuel," W. Parrish, R. 0. Voth, J. G. Hust, T. M. Flynn, C. F. Sindt, N. A. Olien; J. Hord, Editor, Cryogenics Divi- sion, National Bureau of Standards 1156 PAGENO="0005" Dr. James S. Kane Deputy Assistant Administrator for Conservation Energy Research and Development Administation Washington, D.C. 20545 Dr. Harrison H. Schmitt Assistant Administrator for Energy Programs National Aeronautics and Space Administration Code N, NASA Headquarters Washington, D.C. 20546 Dr. James E. Funk Dean, College of Engineering University of Kentucky Lexington, Ky. 40506 Mr. G. Daniel Brewer, Manager Hydrogen Studies Lockeed-California Company Burbank, Calif. 91520 Mr. John A. Casazza, Vice President Planning and Research Public Service Electric and Gas Co. 80 Park Place Newark, N.J. 07101 Dr. Edward M. Dickson, Manager Resources Program Operations Evaluation Department Engineering Systems Division Stanford Research ftstitute Menlo Park, Calif. 94025 Mr. William J. D. Escher- Escher Technology Associates P.O. Box 189 St. Johns, Mich. 48879 Mr. John E. Johnson, Associate Manager Feedstock and Energy Policy Office Union Carbide Corporation 270 Park Avenue New York, N.Y. 10017 Conunander Paul Petzrick Director, Navy Energy, Research and Development Office Headquarters, Naval Materiel Command Code MAT 03Z Washington, D.C. 20360 Dr. Derek P. Gregory Director, Energy Systems Research Institute of Gas Technology 3424 South State Street ITT Center Chicago, Iii. 60616 Mr. Sidney H. Law Director of Research Northeast Utilities P.O. Box 270 Hartford, Conn. 06101 Dr. Fritz R. Kalhammer, Manager Electrēchemical Energy Conversion and Storage Electric Power Research Institute 3412 Hillview Avenue Palo Alto, Calif. 94303 Dr. Ram Manvi School of Engineering California State University of Los Angeles 5151 State University Drive Los Angeles, Calif. 90032 Dr. John W. Michel, Technical Assistant for Advanced Energy Systems Oak Ridge National Laboratory P.O. BoxX Oak Ridge, Tenn. 37830 Mr. Harvey A. Proctor, Chairman of the Board Southern California Gas Company Box 3249 Terminal Annex Los Angeles, Calif. 90051 COMPLETE ADDRESS INFORMATION ON WITNESSES COMPLETE ADDRESS INFORMATION ON PERSONS SUBMITTING STATEMENTS FOR THE RECORD (V) PAGENO="0006" VI Mr. F. J. Salzano Project Engineer for Hydrogen Storage and Production; and Mr. Kenneth C. Hoffman, Head Engineering and Systems Division Brookhaven National Laboratory Associated Universities Inc. Upton, Long Island, N.Y. 11973 Dr. James H. Swisher, Supervisor Exploratory Materials Division Sandia Laboratories Livermore, Calif. 94~5O Dr. Robert H. Wentorf, Jr. Energy Sciences Branch Power Systems Laboratory General Electric Company Research and Development Center P.O. Box 8 Schenectady, N.Y. 12301 PAGENO="0007" HYDROGEN TUESDAY, JUNE 10, 1975 HousE OF REPRESENTATIVES, COMMITTEE ON SCIENCE AND TECHNOLOGY, SuBCOMMITTEE ON ENERGY RESEARCH, DEVELOPMENT AND DEMONSTRATION, Wa~thington, D.C. The subcommittee met, pursuant to notice, at 8 :05 a.m., in room 2325, Rayburn House Office Building, Hon. Mike McCormack (chair- man of the subcommittee), presiding. Mr. MCCORMACK. The meeting will come to order. Good morning. This morning the Subcommittee on Energy Research, Development and Demonstration undertakes the first of two investigative hearings on the subject of hydrogen-its production, utilization, and potential effects on our energy economy of the future. Hydrogen is not a new source of energy. In a sense hydrogen has the potential of playing the same kind of role in our energy system as electricity does today. That is, it is an intermediate form of energy which must be produced from some other primary form, but it is, at the same time, extremely useful for specific applications. Today we have proven technologies for producing hydrogen from water by electrolysis, and from natural gas by a steam reforming process. It is unlikely, however, that the presently accepted processes would be utilized on a large scale in the future. What we are look- ing for, therefore, is an economically feasible way of producing hydrogen in large quantities. The production of hydrogen, even cheaply, is not the complete an- swer, however. If hydrogen is to take its place as a viable component of the energy economy of the future, we must also be able to store, transport, and utilize it in a manner that is consistent with require- ments of our industrial, commercial, and residential energy needs. In a sense, we must undertake a systems appioacli in dealing with this potential new energy technology. One of the most attractive aspects of hydrogen is its cleanliness. The combustion products of hydrogen are in no way detrimental or un- desirable from an environmental point of view. This makes its use, especially in densely populated urban areas much more desirable than the use of fossil fuels. Another attractive feature of hydrogen is its potential compatibility with our existing industrial infrastructure. As a gas it is easily trans- portable, and there is the possibility of using, with certain modifica- tions, much of our investment in natural gas pipelines and ancillary (1) PAGENO="0008" 2 equipment. This issue of compatibility is one that we will pursue in the hearings today and Thursday. We must look at the drawbacks as well as the advantages of hydro- gen. Safety is one. Cost is another. There may be unknown environ- mental hazards associated with new and innovative production proc- esses. We must assure adequate feedstocks for hydrogen production. Another necessary ingredient, of course, is a great quantity of energy. Still another is ingenuity. What we hope to uncover, during the hearings this week, is the ingenuity that would be required to obtain the energy, to use the feedstock to produce hydrogen, and then to use the hydrogen intelli- gently and effectively throughout. our industrial system. Our witnesses today are Dr. James Kane, Deputy Assistant Ad- ministrator for Conservation, Energy Research and Development Administration, accompanied by Dr. Jack Vanderryn, Assistant Di- rector for Energy Storage. ERDA; Dr. Ray Zahradnik, Acting Di- rector, Division of Coal Conversion and Utilization, ERDA; Dr. Harrison Schmitt.. Assistant Administrator for Energy Programs, NASA, accompanied by Mr. R.. D. Ginter, Director of the Energy Systems Division, Office of Energy Programs, NASA; and Dr. James E. Funk, Dean of the College of Engineering, University of Ken- tucky, at Lexington, Ky. So we'll sta.rt out this morning with Dr. Kane. Jim, please make yourself comfortable at the witness table. Dr. KANE. Thank you, Mr. Chairman. I'd like to bring with me to the witness table Dr. Vanderryn and Dr. Ray Zahradnik, who is from our Fossil Energy Branch. Mr. MCcORMACK. Welcome. gentlemen. Jim, if you have a prepared statement, you may put it in the record, and talk from it, or you may read your statement, or proceed in any way you wish. Dr. KANE. Mr. Chairman, with your permission, I will read parts of my prepared statement, and skim over other parts of it. I might register a mild complaint, that you have said a lot of what's in my prepared statement already. Mr. MCCORMACK. I am sorry about that. There being no objection, we shall insert your entire statement in the record, and you may proceed as you like. Dr. KANE. Thank you. [The prepared statement of Dr. Kane follows:] PAGENO="0009" 3 STATEMENT OF DR. JAMES S. KANE DEPUTY ASSISTANT ADMINISTRATOR FOR CONSERVATION ENERGY RESEARCH AND DEVELOPMENT ADMINISTRATION FORTHE SUBCOMMITTEE ON ENERGY RESEARCH, DEVELOPMENT, AND DEMONSTRATION COMMITTEE ON SCIENCE AND TECHNOLOGY HOUSE OF REPRESENTATIVES JUNE 10, 1975 PAGENO="0010" 4 Mr. Chairman and Members of the Committee: Much attention has been given in the past few years to the possible role of hydrogen in our Nation's future energy systems. These hearings are thus appropriate and timely in this regard, and should be helpful in placing the future uses of this interesting and somewhat unique element into proper perspective. I intend to provide you today with a brief overview of ERDA's R&D activities related to hydrogen technology as well as indicate some possible future directions to which this technology may lead us. To assist me in this task, I am accompanied by Dr. Jack Vanderryn, Assistant Director for Energy Storage in Conservation, and Dr. Ray Zahradnik, Acting Director of the Division of Coal Conversion and Utilization in Fossil Energy. It should be noted that hydrogen-related activities are distributed throughout ERDA, and accordingly my testimony this morning will reflect activities related to a number of ERDA programs. Before describing ERDA's activities, I would first like to discuss the role of hydrogen in energy systems. PAGENO="0011" 5 Free hydrogen does not occur naturally; it must be obtained from a primary source of energy such as fossil fuels, uranium or sunlight. Some energy is always lost in the process, that is, the amount of energy that can be obtained from the product hydrogen is less than that used to obtain it. That is the first point I wish to emphasize: hydrogen is not a source of energy itself, but rather a synthetic fuel that must be obtained using energy from another source. In spite of these losses associated with its production, it may be advantageous to synthesize hydrogen for many reasons, and I will give some of these reasons later in my testimony. Hydrogen is widely used today; its production in 1972 amounted to 10 billion pounds. It was as follows: Synthesis of ammonia 35% * . Hydrocracking of petroleum 30% Hydrotreating of hydrocarbons 21% Synthesis of. methanol 8% Other 6% You can see that the two major uses are for fertilizer and oil refining, where it is used to enhance the yield of gasoline and other products from PAGENO="0012" 6 crude oil. Its use for fertilizers is expected to more than double in the-next ten years. An even greater increase can be expected in the 80's and 90's as we develop processes for converting heavier primary fuels, such as coal, to synthetic liquid and gaseous fuels. - By far the largest hydrogen-related program in ERDA is, therefore, that of our synthetic fossil fuel program. I sense, however, that this aspect of hydrogen technology is not what the Committee had in mind for this hearing. I will, therefore, make a few general comments on hydrogen as it relates to synthetic fuels, and go on to other topics. If the Committee wishes further information on this aspect of hydrogen production, I will defer to Dr. Zahradnik who is an expert in these matters. Let me give you my comments: Hydrogen is currently produced almost entirely from natural gas and other highly hydrogenated hydrocarbons. The supply of these materials is decreasing and this decline will continue. The hydrogen needed for coal-derived synthetic fuels will come from the reaction of carbon in coal with PAGENO="0013" 7 water. This reaction, in which the carbon removes the oxygen from the water mOlecule and thus releases hydrogen, is the first step in most of the synfuel processes being developed. Our programs to develop the synthetic fuel process thus include hydrogen synthesis on a very large scale. Most of the hydrogen produced would be subsequently used to obtain convenient fuels, such as methane (synthetic gas) or gasoline-like liquid fuels. These synfuel plants cbuld also produce pure hydrogen, if required. Non-fossil energy sources--fission, fusion and solar--will produce their energy in the form of heat or electricity. As these sources become more predominant, and especially if coal is relatively less available than expected, new technology would be required to be developed to obtain hydrogen from these sources. This has been a brief introduction to the subject. In the rest of my testimony, I will deal more specifically with the details of our hydrogen program. I will not cover in detail, however, those aspects that are * associated with its production from coal or its use in the coal-derived synthetic fuel programs, but I am sure Dr. Zahradnik could answer any questions you may have. PAGENO="0014" 8 PRODUCTION OF HYDROGEN Electric energy can be used to decompose water to obtain hydrogen and oxygen. This process is called electrolysis. Our current program includes research to improve the efficiency of the electrolysis process and to lower the capital cost of the associated equipment. Efficiencies are now about 60 percent; it may be possible to raise them to 90 percent. There are, of course, many uses for the by-product oxygen, which itself is a valuable substance. It may also be possible to obtain hydrogen from water by the use of heat instead of electricity. This process, often called thermochemical watersplitting, cannot be done by simply heating water. It involves multi-step chemical reactions, some of them taking place at high temperatures; but the total process consumes only water and heat, and produces hydrogen and oxygen. Thermochemical processes, in contrast to electrolysis, have not yet been demonstrated on a practical scale. Programs are underway at several ERDA laboratories to determine if such processes can be developed to use solar or nuclear heat. There is also great interest in this concept in both the university and industrial communities. PAGENO="0015" 9 Hybrid processes, using both electric energy and heat to obtain hydrogen. and oxygen from water, may also be possible. The processes by which hydrogen could be produced from coal could be made more efficient (less coal used per unit of hydrogen produced) if additional heat from a non-coal source, such as nuclear, were used. Current state-of-the-art coal gasification processes would require development of special., high temperature materials for such a process and this research is planned. An attractive alternative would be to develop gasification processes that operate at lower gasification temperatures, and thus avoid the difficult materials development. This also will be studied in the coming year. USES OF HYDROGEN Hydrogen can, in principle, serve as a fuel for all conventional uses of energy, including industrial applications, electric power generation, as well as for residential, commercial and transportation uses. It can also be used as a reducing agent in many metallurgical processes, such as steel making. I have already pointed out that it takes energy to produce hydrogen--more energy, in fact, than is PAGENO="0016" 10 recovered when the hydrogen is used. It may still be advantageous, however, to produce and use hydrogen if its use results in a greater overall efficiency of the total system, or results in a greater capability of the system. The following are examples where this may prove to be true: Load-Leveling in Utilities Hydrogen offers a potentially attractive means of storing energy generated by la'rge, central-station generating stations during periods of low demand for subsequent use at times of high demand. This "load- leveling," although it does not result in energy savings, greatly increases the efficiency of the very capital- intensive facilities. It also saves the oil or gas that is usually used for meeting peak demand. It may also be desirable to use hydrogen as the energy storage system in conjunction with inexhaustable but intermittant energy sources such as wind or solar thereby increasing their usefulness. The processes involved in these storage applications would be the electrolysis of water to produce the hydrogen, with storage, and finally reconversion to electricity using fuel cells. Improvements in each of these PAGENO="0017" 11 technologies would be required to lower cost and increase efficiency. Our planned FY 76 program includes R&D in improved electrolysis, storage using solid hydrides, and hydrogen fuel cells. Electrical Generation Electrical energy can be produced directly from hydrogen by using a high efficiency converter such as a fuel cell or by burning the hydrogen in a turbine. The hydrogen fuel cell is thou~ght to have a potential efficiency of perhaps 60 percent. This, coupled with a possible 60 percent efficient coal-to--hydrogen process, would yield an overall efficiency of 36 percent from coal to electricity, which is competitive with conventional steam cycle after penalties for stack gas scrubbing are subtracted. The use of fuel cells have an additional benefit over centralized generation. The cells are modular and need not be installed initially in large size; more can be added as demand increases. They are quiet, safe, and can be located close to load centers, where there may be opportunities to use their waste heat. Fuel cells are also well suited for small utilities, such as those which are municipally owned. To compete economically with current means of electrical generation, the hydrogen fuel cell would have 62-332 0 - 76 - 2 PAGENO="0018" 12 to be priced at about $200/kw. The development cost goal of the more complicated hydrocarbon fuel cell is of this magnitude. Large scale hydrogen production and transmission, therefore, offers a more conservative route for achieving fuel cell introduction. Our program in FY 76 provides for R&D in both conversion technologies-- fuel cell and turbines. SUBSTITUTE FOR NATURAL GAS Hydrogen can be used as a substitute for natural gas or may be mixed with natural gas to extend the use of this scarce resource. Up to 8 percent hydrogen can be added to natural gas without changing equipment for its transport and use. A detailed analysis of this near-term possibility will be performed in FY 1976. Commercial, residential and industrial applications of hydrogen for heating will also be investigated in FY 1976. Experimental programs looking forward to this longer term application may also be instituted in FY 1976. Relative to synthetic natural gas, both capital and resource savings appear possible. Automotive Applications In order to use hydrogen as an automotive fuel, a suitable on-board storage method would require development. PAGENO="0019" 13 It is doubtful that hydrogen would be carried in liquid form, since the liquefaction process is expensive and inefficient. It is also questionable whether liquid hydrogen could be safely stored in an automobile. In our view, the use of hydrogen for automotive applications depends on the development of solid hydride storage technology. We are seeking new hydrides for this application which will be lightweight and can use the exhaust heat to release the hydrogen from the hydride. The weight and. cost of the hydrogen storage system, however, may be a major constraint on the range of the vehicle. DELIVERY SYSTEMS Hydrogen is known to embrittle some kinds of steel under certain conditions. Before a hydrogen delivery system could be put into service, it would be necessary to prove that the chemical effect of the hydrogen on structural materials would not lead to safety problems. Preliminary information indicates that a large part of our current distribution system could be modified to handle hydrogen safely. More information and R&D is needed, however, before we can be assured that our PAGENO="0020" 14 current high pressure pipeline system could be used to transmit hydrogen. We have an ongoing program to investigate hydrogen compatibility with structural materials such as those used in pipelines. ENVIRONMENTAL EFFECTS ASSOCIATED WITH HYDROGEN By far the largest environmental impact associated with hydrogen is that caused by the energy source used to produce the hydrogen. For most applications, the use of hydrogen will produce only water as a by-product. If the hydrogen is used to obtain very hot flames in air, there may be problems from the production of nitrogen oxides. Its use in fuel cells will not produce nitrogen oxides. When added to natural gas, hydrogen could reduce nitrogen oxide formation, since it will allow the gas to be burned "leaner" and hence cooler. Safety problems associated with gaseous hydrogen are similar to and probably no worse than safety problems with other hazardous fuels. The previously mentioned ernbrittlement problem must be carefully considered in relation to pipeline and other pressure PAGENO="0021" 15 vessels. The examination of environmental, social, legal and economic factors has begun, and no insur- mountable problems in the use of hydrogen are anticipated. BASIC RESEARCH In addition to the work already described, which is in direct support of hydrogen R&D, other ERDA research efforts contribute to our overall fund of knowledge in this area. Such activities include research on metal hydrides, photochemical processes, and fundamental materials and chemical research. NAGNITUDE OF EFFORT In FY 1975, hydrogen-related ERDA activities were dominated by the processes related to its production from coal; about $263 million was spent on synthetic fuels process development. About $10 million total was spent on the other technologies discussed in this testimony as follows: $1 million each on production from water, high temperature reactor technology, and storage and delivery systems; $3 million on photochemical research; and $4 million on basic and supporting research. PAGENO="0022" 16 In.FY 1976 we are planning substantial increases in effort, especially in hydrogen production from coal, high temperature reactor technology, and hydrogen conversion technology. Although ERDA has the major responsibility for the Federal hydrogen R&D effort, we intend to continue utilizing other Federal agencies and laboratories in carrying out the program. We will also continue to encourage current industrial activities where hydrogen-related efforts are currently being supported by companies such as Allied Chemical, Bethlehem Steel, General Motors, Gulf General Atomic, Pratt & Whitney, Rocketdyne and Teledyne. Within ERDA we have established a Committee to coordinate our hydrogen energy R&D activities, to assist in identifying problem areas, issues and program planning, and to provide one means of coordinating with the efforts of others. ~ Internationally, we are cooperating with the major European countries, Canada and Japan under the auspices of the International Energy Agency. CONCLUSION In summary, we believe that it is desirable to explore the possibility that economically promising PAGENO="0023" 17 applications for hydrogen energy systems can be developed and we believe that ERDA is pursuing a balanced exploratory R&D program. The opportunities for hydrogen systems to compete for major energy markets will improve as advanced technologies are demonstrated in each aspect of use. Initially our interest in hydrogen, was based on environmental con- siderations, but there now seems to be an equally promising potential for conservation. Widespread use of hydrogen energy systems is not likely to come until late in the 1990's, and would require significant changes in our energy systems. Certain specialized applications such as storage and fuel cells for electric utility applications could come somewhat earlier. Applications showing capital or resources conservation are most likely to happen first. It seems prudent to proceed with research, develop- ment and demonstration of all aspects of hydrogen technology, in order that the use of this unique material becomes a real option in our uncertain energy future. PAGENO="0024" 18 STATEMENT OF DR. JAMES S. KANE, DEPUTY ASSISTANT ADMIN- ISTRATOR FOR CONSERVATION, ENERGY RESEARCH AND DEVELOPMENT ADMINISTRATION; ACCOMPANIED BY DR. JACK VANDERRYN, ASSISTANT DIRECTOR FOR ENERGY STORAGE IN CONSERVATION, ERDA, AND DR. RAY ZAHRADNIK, ACTING DIRECTOR, DIVISION OF COAL CONVERSION AND UTILIZATION IN FOSSIL ENERGY, ERDA I)i~. KANE. Mr. Chairman and members of the committee, much attention has been given in the past few years to the possible role of hydrogen in our Nation's future energy systems. These hearings are thus appropriate and timely in this regard, and should be helpful in placing the future uses of this interesting and somewhat unique ele- ment into proper perspective. I intend to provide you today with a brief overview of ERDA's R. & D. activities related to hydrogen technology, as well as indicate some possible future directions to which this technology may lead us. As I pointed out, to assist me in this task, I am accompanied by Dr. Jack Va.nderryn, Assistant Director for Energy Storage in Con- servation, and Dr. Ray Zahradnik, who is Acting Director, Division of Coal Conversion and TJtilizaton in Fossil Energy. It should be noted that hydrogen-related activities are distributed throughout ERDA, and accordingly my testimony this morning will reflect activities related to a number of ERDA programs. There are representatives of these other programs here in the room today. Before describing ERDA's activities, I would like to discuss the role of hydrogen in energy systems. I believe I'll jump over this first paragraph, since it repeats what you said. The misconception that I wanted to make, because there's lots of confusion, particularly in the press, is that hydrogeni is some great new energy source. Of course, that is not true. Hydrogen is an alternative form of energy. It's a synthetic fuel which we may chose to synthesize and use because of convenience, or because of some of its unique properties, but it is not in itself an en- ergy source. You must always use more energy to get hydrogen than what you can get back from it when you finally use the hydrogen itself. Mr. MCCORMAOK. Jim, if I may interrupt, I want to express my appreciation to you for making that point. I just wish that all the popular press could hear that statement and understand the simple fact. that hydrogen is not a source of energy. It's a fuel that must be produced. I think if all of the press would help the public under- stand that. it would help us toward a more intelligent energy policy. Dr. KANE. Thank you. Hydrogen is widely used today. I have tabulated the uses. Ten billion pounds were produced in 1972~ and its use is increasing. The two uses that dominate in the table on page 2, of course, are the synthesis of ammonia, and the upgrading of crude oil to more useful products, generally gasoline. Uses are expected to increase, as I pointed out, and as you certainly know. The need to raise more food in this country can be expected to cause the fertilizer industry to grow. Later, as the processes come on line, which will derive synthetic fuel from PAGENO="0025" 19 coal, there will be an enormous increase in the demand for hydrogen. The largest hydrogen related program, then, is our synthetic fossil fuel program. The first step of almost all the synthetic fuel program is to react coal with steam to get hydrogen, and, therefore, the synthetic fuel program produces, or will produce, an enormous amount of hydrogen. Of course, they'll turn right around and reuse it again by adding it to carbon atoms to get a hydrogenated synthetic fuel. I sensed that this was not entirely what the committee wanted to hear about, so, in my statement, I didn't go into many of the details of our fossil fuel program. Dr. Zahradnik, who is directing this pro- gram. can certainly give you all the information you wish. If you have questions related to any aspects of the production of hydrogen from coal, Dr. Zahradnik will be pleased to answer them. Today essentially all of our hydrogen is derived from fossil sources. About 7 percent of the total methane, or natural gas consumed in this country is used for the production of hydrogen. It's cracked to give hydrogen. So if we are to have hydrogen in large supply in the future, it will either have to be methane derived, which is impossible with the decline in the supply of methane, or it will have to be coal derived, which is the process to be developed in the fossil energy program. Alternatively we could get it from some new sources of energy, such as nuclear or solar. Now. these nonfossil energy sources produce their energy in the form of heat or electricity, and so as these sources become predominant, and especially if coal becomes relatively less available, new technology will be needed to produce hydrogen from these sources. I will now address the production and use of hydrogen, and some of the problems and technologies associated with hydrogen. First, the production. Electric energy can be used directly to decompose water to obtain hydrogen and oxygen. This process is called electrolysis. A current program within ERDA includes research to improve the efficiency of the electrolysis process and to lower the capital cost of the associated equipment. The efficiency of electrolysis is now about 60 percent. It may be possible to raise that to 90 percent. There are also, of course, many uses for the additional quantity of oxygen which would be produced. However, we've never taken credit for it in our calculations. So electrolysis can augment the ways of getting hydrogen from natural gas and from coal. Electrolysis may not be the only way that we can get it in commercial amounts. However, it may also be possible to obtain hydrogen from water by the use of heat instead of electricity. This process is often referred to as thermochemical watersplitting, and from a practical point of view it cannot be done in one step, sim- ply by heating water. The temperatures would be too high to decom- pose water just by heating it. So it involves a series of steps of chemical reactions. They're cyclic in nature. Some of them absorb energy at high temperatures; others reject energy at low temperatures; by a com- bination of these steps you can get an overall process which basically consumes only water and heat, and produces hydrogen and oxygen. These thermochemical processes, as they are called, in contrast to electrolysis, have not yet been demonstrated on a practical scale. I emphasize the word "practical." There's no question they work in PAGENO="0026" 20 theory and on paper; however, the ingenuity you referred to in your introductory remarks will certainly be needed to make these practical processes. By "practical" I mean economical and feasible. There is considerable interest in this concept in both the university and industrial communities, as I'm sure your subsequent witnesses will bear out. Hybrid processes, using a combination of electric energy and heat to obtain hydrogen and oxygen from water, may also be possible. As coal becomes expensive, or in situations where nuclear or solar energy would be competitive with coal, then we would want to use heat from these other sources to avoid burning coal. We could also in this way enhance the yield of hydrogen we get from coal. The first contender would certainly be nuclear heat from a high tempera- ture gas-cooled reactor. Such processes could save a great quantity of coal. In other words, that would make the process of converting coal to hydrogen much more efficient. This process, however, could not be implemented with the present state-of-the-art. You have to do one of two things. You would either have to use a reactor that generates higher temperatures, such as the graphite moderated gas-cooled reactor; or you would have to lower the temperature at which this process occurs. There are programs within ERDA directed toward both these goals. USES or HYDROGEN I have not considered the use of hydrogen in either the aerospace field or in aeronautics, because I'm sure the subsequent witness, Dr. Schmitt, will be discussing these applications. Hydrogen, as you know, in principle, can serve as a fuel that can replace conventional fuels almost anywhere, including industrial applications, electric power generation. and for residentia.l, commer- ciaL and transportation uses. By "can" I mean there's no technical reason you can't do it, though there may be practical and economic reasons why you might not wish to do it at the current time. Hydro- gen can also be used as a reducing agent in metallurgical processes, such as steelmaking. where we presently use coal. The theme that runs throughout my statement is that in the future, as coal becomes more costly, and if other forms of energy, such as fission, fusion, or solar become cheaper. we will, of course. be looking for was of better utilizing these forms of energy. Also. looking ahead to a possible fossil energy scarcity, which will happen some day. I suppose. it's good t.o think of processes by which we could use new forms of energy to replace coal. Again, I want to bring out this point: Often there are some dis- advantages to the use of hydrogen. You certainTy do sacrifice energy to get liydro~en. in that YOU can never get as much back as von put in in the fi~rst place. But it `still may be advantageous to go through this process, and I've picked out some examples where this may prove to be true. The first of these is load-leveling by the utilities. I'm sure I don't have to tell this committee, of the enormous capital costs of our electrical system. Both the generation system and the distribution system is currently used. I believe. at. ~O to 60 percent of its maximum capacity. The use of hydrogen as a load-leveling means for utility PAGENO="0027" 21 applications is not a saver of energy, but it may turn out to be a very large saver of capital, through the storage of electricity. The utilities must meet demand, and demand varies dramatically with the time of day. Thus, the full capacity of the system is not used for a good part of the day, and if it were possible to somehow generate energy in a conyenient form that could be stored, and then use it subsequently in a period of high demand, this could be a more efficient use of the system. It may be possible to use hydrogen technology to do this by the process of electrolyzing the water during periods of low demands, storing the hydrogen, and using it subsequently to generate electricity at periods of high demand. The processes that would have to be per- fected in order to do this are electrolysis, storage, and fuel cell technology. We haven't at all covered the processes, which have to be performed when you go from alternating current to direct current. It has to be rectified, and then if the fuel cells generate direct current it has to be interrupted, and reconverted back into alternating current. I'm not going to discuss this today. I assume these processes are available, and, indeed, they are becom- ing available, on a commercial level, through solid-state technology and other means. Some further improvements will be required. Mr. MCCORMACK. Are you doing any studies to show the total effi- ciency of the hydrogen peaking system, including use of fuel cells? Dr. KANE. Yes, we are, and Dr. Vanderryn will give you specific data on that, either now or subsequently, whichever you wish. Mr. MCCORMACK. Whenever you see fit. Dr. KANE. The unit operations needed to use hydrogen for this load- leveling application are: Electrolysis, storage, and finally the recon- version to electricity, using fuel cells. Actually, it doesn't have to be fuel cells. You can burn hydrogen in a turbine, but the efficiency of the fuel cells certainly indicates that they would be useful. All of these technologies need improvement to lower their cost and increase their efficiencies and our 1976 program includes R. & D. on all those technologies. I'll have Dr. Vanderryn go into the efficiencies at the end of this next section. In addition to load leveling, hydrogen can also be used to produce electricity directly, using a high-efficiency converter such as the fuel cell, or by burning the hydrogen in a turbine. The hydrogen fuel cell is thought to have a potential efficiency of perhaps 60 percent. This could be coupled with a possible 60 percent efficient coal-to-hydrogen process. Dr. Zahradnik will perhaps expand on that. You see, the idea is to start with a lump of coal and find the most efficient means to convert this to electricity. One route might be to burn the coal directly, and remove the sulfur, and so forth. Another route might be to convert the coal to a synthetic fuel, burn that under a boiler. The third route might be to use the coal to produce hydrogen and use that in a fuel cell. The latter is what I'm discussing today. We think this route of coal-to-electricity would yield an overall efficiency of 36 percent, which approaches today's best fossil fuel plants which have an efficiency of about 40 percent. If you subtract out the penalties imposed by the PAGENO="0028" 22 clean up of the sulfur and the ash in conventional plants, I think the hydrogen fuel cell route would be competitive today. I would like to point out additional advantages of fuel cells for electrical generation. The cells are modular and need not be installed initially in large size. I need not point, out t.o the committee the prob- lems that the utilities are having in bringing on the very large blocks of power in their central stations these days. So the modular aspects of the fuel cells are very attractive. They're quiet, clean, and safe; they can be located close to the load centers, w-hich reduces the need for the large overhead high voltage transmis- sion lines, and by putting them close to the load centers there. may also be opportunities to use their waste heat. One promising, near-commercial fuel cell comes in a package about 25 megawatts. which is a very convenient size for large shopping cen- ters, et cetera. If the waste heat is produced close enough to the con- sumer, you might think of using it. Fuel cells are also well suited for small utilities, municipally owned utilities and some rural organizations, that don't need very large in- staBation. The only way they can get their energy today is by forming cooperatives or buying power from a large utility. To compete economically with present means of electrical genera- tion, t.he hydrogen fuel cell would have to be priced at about $200 a kilowatt, and in my statement I pointed out that the development cost goal of the hydrocarbon fuel cell which is now under commercial con- siderat.ion is approximately of this magnitude. Since the hydrogen fuel cell is almost surely simpler than the more complicated hydrocarbon fuel cell, if they can achieve their $200 a. kilowatt goal, then the hydro- gen fuel cell at $200 a kilowatt should be achievable too. Our program in 1976 provides for R.. &. ID. in bot.h conversion tech- nologies; fuel cells and turbines. The next point I would like to make is that you can substitute hydro- gen for natural gas. up to perhaps 8 percent. There's considerable R.. & ID. going on as to how- much hydrogen you can put in natural gas and use. the current system. I don't want. to commit to a definite number because. as I point, out, there. are still a. number of unknowns. One of them, which I'll discuss later, being the hydrogen embrit.t.lement prob- lem and the effect of hydrogen on the current pipeline transmission system. From the combustion standpoinL it certainly can be substi- tuted for natural gas and burned in ordinary burners. If you wanted to extend the supply of natural gas and had a source of hydrogen~ this would be a way you could use it. LV~TOMOTIVE APPLICATIONS In transportation applications storage is the c.rucial question. We don't believe that liquid or high-pressure gaseous hydrogen would he a practical means of storage. Accordingly we have focused our efforts on solid-state. storage. and by that I mean storing it in solid hydrides. These solid hydride materials represent a higher density method of storing hydrogen. many of them. than liquid hydrogen itself. Tn other words. a cubic foot of these hydrides can contain as much hydrogen as a. tank of liquid hydrogen a cubic foot. in volume. So they're a very efficient. method of storing hydrogen. PAGENO="0029" 23 I don't mean to imply that this is a fully developed technology. There remain great difficulties in this. So our R. & D. program related to transportation emphasizes, very heavily, practical storage mechanisms with solid hydrides the chief candidates. On delivery systems, I want to point out that pipelines are possible storage systems too. They not only deliver the gas to the customer, but they can store hydrogen in their volume, which is rather large, under high pressure. You can pump into the pipeline and then use it subse- quently. It is a big storage mechanism. Before a hydrogen delivery system could be put in service, it would have to be proven that the chemical effect of the hydrogen on the struc- tural materials throughout would not lead to safety problems. We've given this problem some attention during the past year, and we plan to continue. Our preliminary information indicates that a large part of our current distribution system could be modified to handle hydro- gen safely. I'll ask Dr. Vanderryn this later, but I believe that, just as in the electrical business, the distinction is made between transmission and distribution. The big, high-pressure system is transmission, and the distribution system is the relatively low-pressure system that occurs under the streets out here, that's the distribution system. Dr. VANDERRYN. Yes. Dr. KANE. As you pointed out, Mr. Chairman, there are billions of dollars invested in the existing pipeline system. If we could use this, it would be a very attractive feature. So we have an ongoing program in this area. As to environmental effects, I commented, as you did~ that hydrogen looks very attractive from an environmental viewpoint. The largest environmental impact associated with hydrogen will certainly be that caused by the energy sources which are used to get hydrogen in the first place. For most part, water is the only byproduct. Hydrogen is frequently used to obtain very hot flames in air. Be- cause hydrogen does have such a high flame temperature, it has a tendency to form nitrogen oxides. But for most applications you don't have to burn it under the kind of conditions, where you get very high flame temperatures. In fact, for most uses of hydrogen I think the nitrogen oxide problem will be less than for other hazardous fuels. So it is an environmentally attractive fuel. I mentioned the safety problems associated with gaseous hydrogen, which I'm sure Dr. Schmitt will talk about later. Hydrogen has had a bad press, dating back to the Hindenburg acci- dent. Actually, NASA has shown that hydrogen can be handled in large volumes safely. They have a long history of this. There are reasons, which I won't go into today, which actually make hydrogen safer to handle than other fuels. For instance, its very high diffusion rate and its low atomic weight. mean it rises and diffuses away quickly. Other hazardous fuels may tend to form a very dangerous nooL which persists. Although hydrogen may conjure up a picture of the Hinden- burq burning, it can be a safe fuel if it's handled properly. The previously mentioned embrittlement problem will have to be checked very closely. We have already started an examination of the overall environmental, legal, economic and social aspects of hydrogen PAGENO="0030" 24 use, and we see no insurmountable problems. We will continue this investigation. In addition to the work I've already described, which you are ac- quainted with, and which is devoted to the more practical aspects, we have a considerable amount of basic research going on in ERDA to increase our overall fund of knowledge. Things like the basic proper- ties of the hydrogen isotopes will be very important, in our fusion program, and in other programs. Work on hydrides. photochemical processes. and on the fundamental properties of hydrogen, and hydro- gen's interaction with other materials are ongoing. Before I close, I'll mention briefly the magnitude of our effort. In 1975, hydrogen-related ERDA activities were dominated by pro- grams related to synthetic fuels. Now, I don't mean to imply that all the money that the synthetic fuel people spent was specifically aimed at hydrogen, and Dr. Zahradrnk will go into any aspect of that you care to pursue. We spent $263 million on synthetic fuels process development, and much of that, of course, concerns the development of hydrogen-related processes. About $6 million could be specifically identified as con- cerned with hydrogen production. About $10 million total was spent on other technologies~ as follows: About $1 million each on production from water, high temperature reactor technology, and storage and delivery systems; about $3 million on photochemical research; and $4 million on basic and supporting research. In fiscal year 1976 we are planning substantial increases in effort, especially in hydrogen production from coal. high temperature reactor technology, and hydrogen conversion technology. By "conversion" I mean both the fuel cells and the turbines. Although ERDA has the major responsibility for the Federal hydrogen R.. & D. effort. we intend to use other Federal agencies and laboratories in carrying out this program. I might also point out that. there are some industrial activities, reflecting considerable interest in the industrial sector. in hydrogen. Within ERDA we've established a committee to coordinate our hydrogen energy R.. & D. activities to assist. in identifying problem areas, issues~ and program planning, and to provide one. means of coordination with the. efforts of others. It just can't stress this too much. that this committee includes representatives from almost every organization in ER.DA. In conclusion, we believe it's desirable to explore the possibility that economically promising applications for hydrogen energy systems can be developed~ and we believe that ERDA is pursuing a balanced exploratory R.. & D. program. The opportunities for hydrogen systems to compete for major energy markets will improve as advanced tech- nologies are demonstrated in each aspect of its use. Initially our interest in hydrogen was based on environmental considerations. but there now seems to be an equally promising potential for conserva- tion, and I use that "conservation" in the broadest sense. not only conservation of energy. but also conservation of capital resources. Widespread use of hydrogen energy systems is not likely to come until the 1990's. and would require significant changes in our energy systems. Certain specialized applications, such as storage and fuel cells for electric utility applications, could come somewhat earlier. PAGENO="0031" 25 Applications showing capital or resources conservation are most likely to happen first. It seems prudent to proceed with research, development., and dem- onstration of all aspects of hydrogen technology, in order that the use of this unique material become a real option-and I want to emphasize that point. I think ERDA's business is the generation of options. We seek to make it possible that hydrogen use will become real option in our uncertain energy future. That concludes my testimony, and I'll be glad to answer any questions you may have. Mr. MCCORMACK. Thank you, Jim. As always, it's a pleasure to have you here, and a pleasure to listen to your testimony. It's both constructive and stimulating. I have a couple of quick questions. Perhaps a year ago, I visited the KMS Laboratories in Ann Arbor, Mich. At that time they were talking about doing computerized re- search on the thermochemical production of hydrogen, trying to go through all the conceivable chemical combinations that might exist. and put the two-step, and the three-step, and the four-step, and the five-step reactions all in some sort of coherent pattern for analysis and come up with something that would be the most practical in terms of lowest possible temperature, and the most economical chemi- cal reactors. I'm curious to know if you know anything about this? Do you know whether you're supporting this program, or are you doing parallel work? Are you generally working in these areas? Dr. KANE. I could try part of that, but I believe I'll ask Vanderryn to handle it. You mean the thermochemical processes? I(MS was also interested in using fusion neutrons directly to dissociate water. Mr. MCCORMACK. At that time they were talking about the thermo- chemicals. Dr. VANDERRYN. We have talked with the KMS people, and the kind of approach that you mention, Mr. Chairman, on the thermo- chemical cycles is going on in a large number of laboratories in the United States and abroad. We are supporting work at Los Alamos, Oak Ridge, and Argonne. There are also a number of industrial organizations including General Atomic and Westinghouse who are investigating these thermochemical cycles. There are, as you mentioned, a large number of possible cycles, and the first step is to put these on a computer to examine the thermodynamics and determine the most. favorable conditions for these cycles. The work at KMS is supported by our Division of Military Appli- cations. I am not certain whether they are supporting the thermo- chemical work in particular. But there's a large effort going on in the United States, some of it supported by ERDA, looking at these various thermochemical cycles. Mr. MCCORMACK. One would think that the answers. that the best options, from such a study would be available in a relatively short time period, of a few months. Is that too optimistic? PAGENO="0032" 26 * Dr. VANDERRYN. The problem with these cycles, as Dr. Kane men- tioned, is not simply having the results from the paper studies. It's then going into the laboratory, and then going to a. small engineering scale to really see whether one c.an engineer these processes and whether the efficiencies a.nd their costs would be competitive. So I would say it will be on the order of 3 t.o 5 years before. we begin to get a reasonably good indication of whether, on an engineering scale, these processes might be competitive. Mr. MOCORMACK. I appreciate that, but I wonder if I could ask another quick question. On paper at least, how long do you think it would take you to give you some good candidate processes? Dr. VANDERRYN. We've beginning to get some good candidate processes on paper now. Mr. MCCORMAOK. Good. Have you considered also such matters as the use of byproduct oxygen in waste processes in the incinerat.ing of waste? Does that make any sense to include oxygen in your economic balance sheets for these purposes? Dr. VANDERRYN. As Dr. Kane mentioned, in waste processing. oxy- gen certainly can be used. I'm not certain whether this use would be as large as the quantities that we might have available if we go into a large hydrogen economy, I'm not certain. I think t.he waste people would have to look at that more specifically. I cannot answer your question in detail. But we certainly could provide an answer to you. Mr. MCCORMAcK. It really is a. thought. for consideration. Mr. Brown. Mr. Baowx. Thank you~ Mr. Chairman. Just a couple of points. I'm very much interested in that particular area. Out in California there's a. great deal of interest in hydrogen as an automotive fuel. Is it true that storage is the largest. problem that inhibits the expedited use of hydrogen as a. fueL and would your research on hydrides resolve this problem in the near future. or are there other major programs with re- gard to it.s uses? Dr. KANE. Jack, may I refer that to you? Dr. VANDERRYN While it has been shown that. the interna' combus- tion engine can operate on hydrogen successfully one would need to optimize engine design. It is an engineering problem. \~\Te feel that the real problem is to find a~ suitable, sa.fe and economic way to store hydrogen onboard. The problem is that the current hy- drides that we have available, the iron-titanium hydride, for examples that is being looked at for stationary storage applications, is too heavy to use onboarcl. For the lighter materials, like magnesium hydride, it turns out that the energy required to drive the hydrogen off the hy- dride for use is probably too great for onboard vehic'es. So one has to find a suitable hydride, perhaps other afloys. for onboard use. We don't understand enough about the fundamental behavior of hydrides to be able to exactly predict what compound this might be. Thus it simply requires additional work to. hopefully. find a suitable compound that is cheap enough. light enough, and effective to be. suit- ably used onboard the automobile. Mr. BROWN. How much effort is put into this program? PAGENO="0033" 27 Dr. VANDERRYN. The hydride work at ERDA is, I believe, about $3 million. Which includes fundamental and applied work. But I can get you a more exact number on that. [The information follows:] In fiscal year 1975, about $2.6 million was spent on hydride R. & D. Mr. BROWN. There is a small firm in Utah that's worked diligently on the hydrogen processes for automotive propulsion. There's even a film out on this now, which I saw a couple of weeks ago, and there are some rather interesting economic projections, which indicate that the cost of using hydrogen as a fuel would be less than that of gasoline, given certain assumptions with regard to taxation, and so forth, which may or may not be true. But if further development is being held up by the storage problem, I would think that possibly a substantial effort could be justified in trying to resolve that in the fairly near term future, in view of the amount of emphasis which is being put on reducing the demand for gasoline. The current debate on the energy bill, for example, illus- trates this. I shall not press the point, but I would like to have it given some consideration. Also, under basic research you mention photochemical processes, but I do not note any reference. to the nature of those processes in your testimony, Dr. Kane. Could you elaborate just a little bit? Dr. KANE. As I understand it, they are processes where photons pro- duce hydrogen from water directly when they shine on certain oxides. Is there anyone here to address that? Dr. VANDERRYN. Dr. Ste.venson. Dr. STEVENSON. There is some research going on, to better under- stand the photosynthetic process, which I believe is the research you're referring to. Some of this is being done at the University of California. The idea here is to perhaps interrupt the natural process of separat- ing, splitting, the hydrogen and oxygen in the water, and recovering the hydrogen separately. This is in the very early stages, and it would probably take a lengthy research effort to make this a viable process. Mr. BROWN. Is this related to the. thermochemical processes? Dr. STEVENSON. No; this is not related to thermochemical. This is using solar energy for low temperature synthesis, as a source. Mr. MOC0RMAcK. Would the gentleman yield on that? Mr. BROWN. Certainly. Mr. McCORMACK. When you use the word "photosynthetic" are you using it in the classical sense, are you talking about the chlorophyll reaction, for instance? Dr. STEVENSON. Yes. The photon enters into the chlorophyll reac- tion and causes, through a very complex mechanism, which is still not well understood, through electron transfer reactions, the splitting of the water molecule. In the photosynthetic process nature produces oxy- gen as its product. Man would like to be able to alter that in such a way that hydrogen is a new product, and not oxygen. Mr. MGCORMAcK. Are there not some reactions using solar energy enabling you to procure hydrogen directly, or is it methane? Dr. STEVENSON. It's usually methane. Mr. MCCORMACK. Thank you very much. Mr. Brown, do you have further questions? Mr. BROWN. I don't have any further questions. 62-332 0 - 76 - 3 PAGENO="0034" 28 I would just comment that Dr. Kane used the term. or the adjec- tive, ubiquitous, in referring to hydrogen, and the general connotation is, with regard to the use of "ubiquitous," that it is an annoying situa- tion. I hope that does not turn out to be true with hydrogen. Mr. MCCORMACK. Thank you~ Mr. Brown. Mr. Harkin. Mr. HARKIN.. Thank you, Mr. Chairman. Mr. Kane, on page 5 you talked about thermochemical watersplit- ting. Could you clarify one point for me? You said this splitting cannot be done by simply heating water. Then you said "the total process consumes only water and heat." Dr. EIAN~. Yes. Let me try to explain that a little better. Water, of course, is H20. and if you heat it hot enough it will come apart to its component atoms. But under normal conditions, that "hot enough" is so hot that it's not practical. So you can not just take a container, put water in it, and heat it until it comes apart to make oxygen and hydrogen. Mr. HARKIN. How high do you have to get it? Dr. KANE. The higher you get it, the higher the pressures of its two components go. But to get any reasonable pressures you have to go to 2,500 degrees Centigrade, something like that, which is 5,000 Faren- heit., very hot indeed. There are not any materials that you can use to hold the water at those temperatures. So, to take it apart in a single step, in which you just heat it, is totally impractical. It's possible, but totally impractical. Mr. HARKIN. I see. But it could be a part of a step of a process? Dr. Kane. If you take a number of steps~ and don't just take it apart in one step, but add heat to get products, and then cycle through other steps, then you can do it at lower temperatures. That's the whole point, yes. Mr. HARKIN. I see. What you are saying, then, is that it is inefficient to use some other source of energy to get those extremely high tempera- tures. Is that what you're saying? Dr. KANE. It's now impossible with our knowledge of materials. There's no container that you could put it in to hold it at these high temperatures. Mr. HARKINS. I see. It is a container problem? Dr. KANE. It's a materials and container problem. There may be other problems, but predominantly it's a materials problem, yes. Mr. HAREINs. I was thinking of that in terms of using intense en- energy~ heat from the Sun. and that type of thingS to reach those tem- peratures. which could be done quite easily. Dr. KANE. That's right. There is no material that you could contain the hydrogen in where it would dissociate appreciably. Mr. HARKINS. I see. Is there some research goin~ into that? Dr. KANE: Into the multistep approach, rather Than trying to de- velop materials which are probably beyond the capability of tech- nology to reach. Rather than do that, we've chosen to go the multistep process. Mr. HARIcINS. Could solar energy. then, be used in that multistep process? PAGENO="0035" 29 Dr. KANE. It's conceivable that it could be used, yes. In fact, the two candidates that most scientists talk about for doing this are nuclear energy and solar energy. Mr. HARKIN. What is the magnitude of effort that actually would be going into something like that? Dr. KANE. Within ERDA, Dr. Vanderryn can probably give you the number. I want to point out that, so some of your later witnesses from the. university sector will testify, there's a lot of academic interest in this now, and so ERDA doesn't represent all the effort. Dr. Vanderryn, how much are we doing? Dr. VANDERRYN. It's in the neighborhood of $`/2 million per year at the present time. But, of course, there's other related fundamental re- search that is also going on. What these cycles involve is adding various chemical substances to the water, which are than recycled in a closed system themselves. This permits us to lower the temperature at which we can get off the hydrogen and the oxygen. Mr. HARIcIN. I see. I am interested in that. Where is it being done? Dr. VANDERRYN. It's being done at a number of institutions a num- ber of ERDA laboratories, like Los Alamos, and Argonne. I think Dr. Funk, who's testifying later, will talk in more detail about that. He has done considerable work in this area at the University of Ken- tucky. Also, in a number of foreign laboratories work is underway, and also a number of commercial companies in the United States. Mr. HARKIN. Is there no consumption of any of the chemical sub- stances that are used? Dr. VANDERRYN. Theoretically, there's no consumption. Of course, in any cycle like this, on an engineering scale, you will have small losses in the cycle. It's never 100 percent recyclable. The problem is to minimize the losses in such cycles especially if the cycle involves a fairly high cost chemical. Mr. HARKIN. I see. Thank you. Mr. MCCORMAOK. Thank you, Mr. Harkin. Mr. Thornton. Mr. THORNTON. Thank you, Mr. Chairman. At risk of either getting into an area where research is going on which I do not know of, or exploring an area where there may be scientific reasons why this cannot be done, still I want to ask whether- and the question occurred to me the other day when I was reading about the properties of hydrides and storing hydrogen more compactly and in greater densities than liquid hydrogen itself-has experimenta- tion gone forward with, for example, uranium hydride? Dr. KANE. Let me try to answer that. There are many, many elements that form stable hydrides. Uranium hydride, for example, has a very high hydrogen content, but it also is very difficult to disassociate. Therefore, to get the hydrogen off you have to heat it to a very high temperature. So the hydrides we're looking for should not only contain a high volume of hydrogen, but they must also give this hydrogen up at a reasonable temperature. Otherwise, you waste energy heating them PAGENO="0036" 30 to get the hydrogen back off. For instance, in traiisportation, you'd like to store the hydrogen so that you can use the heat from the exhaust of the engine to pull the hydrogen from the storage system. Mr. THORNTON. I am pressing toward another point, and with some concern. Uranium hydrides do exist? Dr. KANE. Oh, yes. Mr. THORNTON. How about the deuterium type rather than hydrogen, using uranium deuteride and using it in connection with laser de- vices, where presently liquid hydrogen, I believe, is used in a. fusion reactor. Has that concept been explored? Dr. KANE. I believe the use of deuterium would be impractical, un- less you had it in a. closed system where you recovered it. Deuterium is a naturally occurring material, but it costs to separate it from the hydrogen, in the first place. Deuteriuin is not t.oo different from ordinary hydrogen. I'm not sure I'm helping you, Mr. Thornton. Mr. THORNTON. Are you familiar with the work, I believe it was at the I~fS Laboratories, where the. laser pellet system was used to achieve a release of energy from a fusion source? Is that pellet corn- posed of~ as I have supposed. just. deuterium? Mr. McCo~rAcK. I think there are a. number of modifications, a num- ber of designs, of pellets, of deuterium pellets. And I think in pure theory there. has been discussion all over the world of using uranium- 235 with them so that you get some sort of a combination fusion-fission reaction. Mr. THORNTON. Research has gone forward. The property of a hy- dride is interesting to me from the sta.ndpoint of storing deuterium in a ve.ry compact way, and I wanted t.o ask if resea.rch has been explor- ing that concept? Dr. KANE. I might point out, without getting involved in classified subjects~ that the Division of Military Applications for yea.rs has had quite an extensive program on all sorts of hydrides, and they have a lot of background information on that. Mr. THORNTON. Thank you. Mr. MCCORMACK. Thank you, Mr. Thornton. May I ask a question, Dr. Kaiie? How serious is hydrogen embrittiement in mild steel piping at am- bient temperatures? Dr. KANE. If you don't. mind, there is a gentleman in the audience who has been doing a. lot, of this work for ER.DA. Could I call upon him? Mr. MCCORMAOK. Certainly. Dr. KANE. He's Dr. James Swisher from the Sandia Laboratories. Dr. Swisher, could you address that point? Dr. SWISHER. We have an ongoing program that's been very active this fiscal year. We are investigating the properties of steels in hy- drogen environments to see how low priced steels might compare with more expensive materials. What we have found is that ordinary mild steels are really not too bad, hut they're not quite as good as stainless st.eels, which are 5 to 10 times more expensive. Our feeling is that perhaps you might be able to use a. coating, or a thin liner, to protect pipe1iiies~ or perhaps limit the operating 9tre~. PAGENO="0037" 31 We don't feel that the problems of putting hydrogen into existing natural gas pipelines are insurmountable. Dr. VANDERRYN. I should also point out that it does depend on the pressure. In low pressure systems it's not a serious problem. As you increase the pressure, the problem would become worse. Dr. KANE. That's why we distinguish between the distribution and transmission systems. As you probably know, there are many places in the world today using mixtures of carbon monoxide and hydrogen. As long as that's done in cast iron pipe, and low pressures, there is no problem. It's where you get to the very high pressures for things like transcontinental pipelines that you might get problems. Mr. McCor~rAcIc. It would seem that a. systems analysis of this en- tue question early on would be extremely helpful so that you could determine what the options are and what options you do not have with respect to hydrogen transmission questions. Dr. KANE. Yes. I agree completely, and we intend to do this in our existing program. Mr. McCoRi~rAcI~. You mentioned also the possibility of 36 percent efficiency from coal to electricity, and 60 percent efficient coal-to-hydro- gen process, and the hydrogen fuel cell having a potential efficiency of 60 percent, but you sort of cast it in terms of for the future. Do you have any idea when those efficiencies might be reached? Do you have any general projection in time? Dr. KANE. I'd like to refer the gasification question to Dr. Zahrad- nik; and the hydrogen fuel cell question to Dr. Vanderryn. Dr. ZATIRADNIIc. The 60 percent figure is probably attainable for the coal-to-hydrogen process. If you were to arrange a more intimate swap of energy, it might be even better. We would go along with that fig- ure, perhaps even add a few percent. Mr. MCCORMACK. Thank you very much. Dr. KANE. Armd the 60 percent in the fuel cells? Dr. VANDERRYN. In certain kinds of fuel cells, the 60 percent is an attainable figure today, and I hope that perhaps with additional work we could improve that considerably. Mr. McC0RMACIC Commercial size, 25 megawatt fuel cells? Dr. VANDERIiYN. We're not at that size as yet. Those really need to be fully demonstrated at that size level. But we certainly can attain 60 percent in laboratory size fuel cells. Mr. MCCORMAOK. Jim, gentlemen, thank you very much. We appre- ciate your testimony. Our next witness is I)r. Harrison Schmitt, Assistant Administrator, Office of Energy Programs, National Aeronautics and Space Admini- stration, accompanied by Dr. Ginter. Do you have Dr. Ginter with you? Dr. ScJnIITT. I think lie's with me. If you can't see him, your eyes are worse than mine. Mr. MCCORMACK. Mr. Ginter, Director of Energy Systems Divisuon~ Office of Energy Programs, for NASA. Jack, it is always good to have you back again. Dr. SCHMITT. Sir, it's good to be here. Mr. MCCORMACK. If you w-ish, yOu may submit your statement for the record as it is and speak from it. Dr. SCHMITT. I will do that, submit it as it is. PAGENO="0038" 32 Mr. MuCoR~rAcK. With no objection, it will be submitted in the record as it is. Dr. SCIDII'Ii'. I may skip around a little bit. [The prepared statement of l)r. Harrison H. Schmitt is as follows:] STATEMENT OF DR. HARRISON H. SCHMITT, ASSISTANT ADMINISTRATOR, OrrIcE OF ENERGY PROGRAMS, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION Mr. Chairman and members of the committee: I appreciate the opportunity to discuss hydrogen with you this morning. As you know, hydrogen has played, and will continue to play, a very important role in meeting aerospace energy needs. We have nearly 20 years of experience in the use, handling, and storage of hydrogen. Hydrogen might, realistically, be called the space fuel. Liquid hy- drogen propelled the Apollo-Saturn missions, provided power through the Apollo spacecraft fuel cells, fuels our Centaur launch vehicle, and will be used to fuel the Space Shuttle Hydrogen is also a very important consideration in our Aeronautics program. It will be needed to manufacture liquid fuels from coal and, at some time in the future, it may fuel advanced transport aircraft. I believe that other witnesses will testify concerning the unique nature of hydro- gen, its place as the lightest chemical element, and the fact that it does not occur naturally in free form on earth. The fact that hydrogen must be manufactured is both an advantage and a disadvantage. From some standpoints, hydrogen is similar to electricity in that it must be created from other energy sources and that some energy is lost in the process. Both electricity and hydrogen, after being created, can be used to link a variety of energy sources with eventual consumers via transmission and distribution systems; pow-er lines in the case of electricity and pipelines in the case of hydrogen. How-ever, unlike electricity, hydrogen is more easily stored, particularly in its gaseous form. Hydrogen is, therefore, a truly unique element, it is an important and necessary element in a large number of chemical processes; it can be used as a synthetic fuel; it is an "energy storage device"; and it can link energy sources to energy consumers. Practically all the hydrogen now- produced in this country is manufactured from natural gas. Obviously, if hydrogen is to be widely used in the future, regardless of how- close to a "Hydrogen Economy" the Nation moves, it will be essential that it be produced someday from feed stocks other than natural gas. Until the formation of ERDA, hydrogen research and technology was receiving little focused attention in the National Energy R~D planning efforts. Based on NASA's experience with hydrogen over about two decades, our recognized need to fully understand the advanced technology required to assure an economic and plentiful supply of hydrogen for aerospace needs, and an aw-areness that the use of hydrogen would most likely increase rather than decrease in the future, we initiated an in-house Hydrogen Energy Systems Technology (HEST) study about nine months ago. Many other studies and reports on hydrogen have been prepared. Some of these have advocated the so called "Hydrogen Economy' while other have been much less optimistic. None of them. however, treated hydrogen as a distinct entity in Energy R&D planning. w-ortl1y of a focused technology advancement program to assure an economical supply capable of meeting the increasing demands. The HEST study is designed as a two-phase effort during Fiscal Years 1975 and 1976. Our objective in the first phase is to define the technology advances which are necessary in relationship to the projected demands for hydrogen in all "use" categories. Our approach is to assess the status of hydrogen technology and then to outline the research and technology advancements required to meet various levels of projected demand. We have formed a small study project at our Jet Propulsion Laboratory to lead the HEST study. Au Inter-Center Working Panel. formed from the other NASA Centers, is being used to provide the broad base of experienced technology support which is required. The study is also supported by a special Review Group w-hich has selected membership from other government agencies. industry. and universities. Our hope is that by using the experience of these people, and resolv- ing their varying perspectives, w-e can achieve an objective definition of the work w-hich must be done iii Hydmogen Energy Technology. PAGENO="0039" 33 HEST RESULTS As expected, the initial results of the NEST study largely confirm many of the conclusions which have already been reached by others. It is also serving the criticaly important function of focussing the attention of a rather large repre- sentation from industry, government, and the academic community on the entire range of hydrogen technology problems at the same time. We have been encouraged by the remarkably consistent agreement which has developed among these various groups. Some general observations are as follows: Hydrogen is now being widely used in a variety of applications and it represents a commodity value of over one billion dollars per year. The major uses of hydrogen are: Manufacture of ammonia for agriculture fertilizer. Petroleum refining (hydrocracking and desulfurization). Methanol Synthesis. Production of chemicals. Reducing agents. Hydrogenation of fats and oils. Clean combustion. Industry fuel when hydrogen-rich gas is a by-product of other manufactur- ing, such as chlorine. The use of hydrogen for the conversion of coal to liquid and gaseous forms, although not a major consumer of hydrogen at this time, will require ex- tremely large amounts of hydrogen in the manufacture of these synthetic fuels. Hydrogen is expected to become increasingly important in the reduction of iron in making steel. In NASA's own programs, the Space Shuttle will require considerable amounts of liquid hydrogen in the future. TECHNOLOGY STATUS Without going into specific detail, the general status of hydrogen technology can be placed in perspective by viewing the problem as comprising three major areas: End-Use; Storage and Distribution; and Production. The technology of end-use is relatively advanced. That is, we know how to burn hydrogen, and how to use it effectively and efficiently, when it is available at an economical price. Storage and distribution technology ~5 less advanced, but is probably adequate for immediate future requirements. It is in the broad area of production where the need for technology advance- ment is most critical. As I have stated, the present supply of hydrogen is ob- tained almost entirely by using natural gas as a feed stock. This must be changed if there is to be hydrogen available to meet even the lowest levels of projected demands. PRODUCTION It is possible to use nearly any energy source to manufacture hydrogen. The critical questions are: (1) which of the many techniques, that do not require natural gas, are economically viable, and (2) which techniques can be developed and demonstrated in time to meet the expected demands. Production techniques fall into three broad categories: 1. Conversion of hydrocarbon fuels in combination with wa'ter and oxygen to form hydrogen. Each such process requires that some form of hydrocarbon fuel (nil, natural gas, or coal) be available. 2. Conversion of electricity to hydrogen by electrolysis. The technique is rela- tively far advanced and available for use today. However, it demands that there be excess and inexpensive Selectric power generating capacity available. I should note that any non-technical factors must be considered when speaking of the conversion of electricity to hydrogen and that within the short time available today, it is ~iot possible to place all of these in a proper ierspective. 3. Thermal dissociation of water. This is an attraCtive, potential means of obtaining hydrogen. These processes could conceivably use any energy source, particularly nuclear and solar. I believe it is fair to state that the technology of thermal dissociation, regardless of heat source, is in its infancy. The promise PAGENO="0040" 34 and potential is on paper. Our ability to efficiently and economically obtain hy- drogen in this manner is critically dependent on the advances which can be made in a wide range of inter-related technologies. Some of the most important include high temperature materials; break-throughs in high temperature and efficient heat exchangers: more complete and detailed understanding of the physics and chemistry of the various processes; and a multitude of other factors too numerous to mention. It may be that the importance of advancing the technology of hydrogen pro- duction can be best emphasized by recognizing that approximately T% of the natural gas production of the Nation is now used to manufacture hydrogen. It appears to be imperative that we quickly learn how to obtain hydrogen economi- cally from other energy sources. These initial and preliminary results of the HEST study are not intended to represent new or startingly different data from what has been documented in other papers and testimony. They do reflect the perspective which has been developing in the broad hydrogen community and the baseline from w-hich com- prehensive and detailed technology advancement plans can be generated. We expect to continue the second phase of this effort during Fiscal Year 1976. Using the general approach developed in the first phase. we will be ex- ploring in considerable detail the definition of the technology advances actually required to assure that: hydrogen is available, can be properly stored, and safely used. Many of the potential uses of hydrogen, such as: "clean fuel"; energy storage: fuel for fuel cells; and as a fuel for selected transportation modes, w-ill be analyzed in much more detail. Our objectives are to document the needs for hydrogen in as realistic a manner as possible. to define the research and technology advances which are mandatory to obtain the quantity of hydrogen needed and to relate these in a comprehensive plan which could be implemented in the Fiscal Year 1977 period, if actually warranted. Our w-ork will continue to be in direct cooperation with ERDA and in support of that Agency's developing National plans. Speaking personally. I believe that there is no question but what we will eventually have some form of a "Hydrogen Economy." In fact, by my standards. the present billion dollar per year industry represents a good start. There is also no question in my mind but that the need for hydrogen wi'll continue to increase in the future. I suspect that we have just begun to ap- preciate the many uses for this unique element. I believe that hydrogen. in addition to its uses in manufacturing, has a vital role in linking energy sources to energy consumers. I question whether the Nation can. or should. at this time, firmly commit only to electricity as our prime means of energy communication in the future. I also know that we must be realistic in our expectations concering the wide- spread availability of hydrogen as a means of energy distribution. Instead of taking extreme positive or negative positions, we must conduct the studies and implement the technology advancement plans which w-ill enable the Nation to most effectively obtain and use this unique vital element. STATEMENT OP DR. HARRISON H. SCHMITT, ASSISTANT ADMINIS- TRATOR FOR ENERGY PROGRAMS, NATIONAL AERONAUTICS AND SPACE ADMINISTRATION; ACCOMPANIED BY R. D. GINTER, DIRECTOR, ENERGY SYSTEMS DIVISION, OFFICE OP ENERGY PROGRAMS, NASA Dr. ScH~rrrr. I think it's symbolic of the infancy of commercial hydrogen technology that we've all given each others' testimony this morning. Not much has been done relative to future n~d. in my opinion, al- though much is being done, as Dr. Kane has indicated. ERDA has recognized this deficiency, as their entire testimony shows, and we are working with them to rectify it as rapidly as possible. As you know, hydrogen has played, and will continue to play, a very important role in meeting the aerospace energy needs of the future and PAGENO="0041" 35 the present. We have in NASA nearly 20 years of experience in the use, handling, and storage of hydrogen. Hydrogen might, realistically, at the present time be called primarily a space fuel, which is its largest use as a fuel. Liquid hydrogen has propelled the Apollo-Saturn mis- sions; it's provided power through the Apollo spacecraft fuel cells; at present fuels our Centaur launch vehicle for many of the unmanned satellite launches; and will be used as a fuel in the Space Shuttle. Hydrogen is also a very important consideration in our aeronautics program, particularly the program of the future. It will be needed to manufacture liquid i~uels from coal. As I have already noted, at some time in the future it may, in fact, fuel advanced transport aircraft. The fact that hydrogen must be manufactured is both an advantage and a disadvantage to us. From some standpoints, hydrogen is similar to electricity in that it must be created from other energy sources and that some energy, as we have discussed already today, is lost in the process. Both electricity and hydrogen, after being created, can be used to link a variety of energy sources with eventual consumers via trans- mission and distribution systems; power lines in the case of electricity, and pipelines in the case of hydrogen. However, unlike electricity, hydrogen is easier to store, and particularly in its gaseous form. Practically all the hydrogen now produced in this country is mann- factured from natural gas. Obviously, if hydrogen is to be widely used in the future, regardless of how close to a hydrogen economy the Nation moves, it will be essential that it be produced some day from feedstocks other than natural gas. As you are aware, I am not quite as pessimistic as others are on the future supplies of natural gas, at least in the interim period of the next 10 years. If we do the right things, I think we can find lots of natural gas. But that doesn't mean we shouldn't look for another way of producing hydrogen. Until the formation of ERIDA, our hydrogen research and tech- nology was receiving relatively little focused attention in the Na- ITional Energy R. & D. planning efforts ,and, therefore, in mid-1974, we in NASA began to study the total problem, as we could define it. Based on our experience with hydrogen over two decades, our rec- ognized need to fully understand the advanced technology required to assure an economic and plentiful supply of hydrogen for aerospace needs, and an awareness the the use of hydrogen would most likely increase rather than decrease in the future, we initiated an in-house hydrogen energy systems technology study about 9 months ago. The acronym, HEST, coincidentally and not by design, stands for horse in Norwegian, and so it's probably an appropriate ancronyrn. Mr. MCCORMAcK. Not many persons besides you in NASA would know that. [Laughter.] Dr. Scm~iirr. Many other studies and reports on hydrogen have been prepared. and Fin sure your library shelf, like mine, has a fair stack of those. Some of these have advocated the so-called "Hydrogen Economy", while others have been less than optimistic. None of them, however, treated hydrogen as a distince entity in energy R. & D. planning, worthy of a focused technology advancement program to PAGENO="0042" 36 assure an economical supply capable of meeting the increasing demands. The REST study is designed as a two-phase effort during fiscal years 1975 and 1976. Our objective in the first phase is to define the technology advances which are necessary iii relationship to the pro- jected demands for hydrogen in all use categories. Our approach is to assess the status of hydrogen technology and then to outline the research and technology advancements required to meet various levels of projected demand. We formed a. small study project at. our jet propulsion laboratory to lead the REST study. An intercenter working panel was formed from the other NASA centers. and is being used to provide the broad base of experienced technology support which is required. The study is also supported by a. special review group. which has selected mem- bership from other Government agencies. such as ERDA, the NBS, the. Department of Interior and the Department of Agriculture, and from industry and the universities. Our hope is that by using the experience of these people. and resolving their varying perspectives~ we can achieve an objective definition of the work which must be clone in hydrogen energy technology. As expected. the initial results of the REST study largely confirm many of the conclusions which have already been reached by others. It is also serving, maybe more importantly. the critically important function of focusing the attention of a rather large representation from industry, Government. and the academic community on the entire range of hydrogen technology problems at the same time. We have been encouraged by the remarkably consistent agreement which has developed among these groups. Some general observations are as follows: First, that hydrogen is now being widely used in a variety of applications, as we've already heard today. and it. represents a commodity value of over $1 billion per year. although that's a. difficult. number to estimate because it's an intermediate element of many processes. Second. the major uses of hydrogen that we see are: The manufac- ture of ammonia for agriculture fertilizer; petroleum refining, which includes hyclrocrac.king and clesulfurization; methanol synthesis and the production of inorganic and orga.nic chemicals such as reducing agents used in a. variety of chemical processes; hydrogenation; clean combustion. particularly in the case of space fuels; and as an industry fuel. when hydrogen-rich gas is a. byproduct of other manufacturing. such as that of chlorine. Third, the use of hydrogen for t.he conversion of coal to liquid and gaseous forms. although not a major consumer of hydrogen at this time, will require extremely large amount of hydrogen in the manu- facture of these synthetic fuels. as we look to satisfying the national goal of about. 1 million barrels a day equivalent in 1985. Fourth. hydrogen is expected to become increasingly important. in the reduction of iron in making steel. . In NASA's own programs. the Space Shuttle will require consider- able amounts of liquid hydrogen in the near future and on into the 1980's and subsequent years. Mr. MCCORMACK. W~liat does this "million barrels a. day equivalent in 1985" mean PAGENO="0043" 37 Dr. SCHMITT. The President's statement in February, I believe, where we're going to attempt to produce about- Mr. MCCORMACK. A million barrels a day, for instance, of synthetic fuel? Dr. SCHMITT. In synthetic fuels. That will demand considerable hy- drogen, which is quite a bit of pressure on us to come to an answer on the question which your committee is asking us as a nation, not us as NASA necessarily. Mr. MCCORMACK. Thank you. Dr. SCHMITT. Without going into specific detail, the general status of hydrogen technology can be placed in perspective by viewing the problem as comprising three major areas: The end-use; storage and distribution; and production. The technology of end-use for hydrogen is relatively advanced. That is, we know how to burn hydrogen, and how to use it effectively and efficiently, when its is available at an economical price. The storage and distribution technology is less advanced, but is probably adequate in terms of its base for immediate future requirements. It is in the broad area of production where the need for technology advancement is most crucial, and that has, of course, dominated our discussion today. As I have stated, the present supply of hydrogen is obtained almost entirely by using natural gas as a feedstock. This must be changed if there is to be hydrogen available to meet even the lowest levels of the projected demands. It's possible to use nearly any energy source to manufacture hydro- gen. The critical questions are: Which of the many techniques, that do not require natural gas, are economically viable; and which tech- niques can be developed and demonstrated in time to meet the expected demands. The 1?roduction techniques fall into three broad categories, as have been covered by Dr. Kane: The conversion of hydrocarbon fuels; The conversion of electricity to hydrogen by electrolysis; and The thermal dissociation of water. Our ability to efficiently and economically obtain hydrogen in this manner is critically dependent upon the advances which can be made in a wide range of interrelated technologies. Some of the most im- portant include: High temperature materials; breakthrough in high temperature, efficient heat exchangers; and more complete and detailed understanding of the physics and chemistry of the various processes; and a multitude of other factors too numerous to mention, but which must be understood in a broad systems point of view, as you have sug- gested, Mr. Chairman. It may be that the importance of advancing the technology of hy- drogen production can be best emphasized by recognizing that ap- proximately 7 percent, as Dr. Kane stated, for the natural gas production in the Nation is now used to manufacture hydrogen. It appears to be imperative that we quickly learn how to obtain hydrogen economically from other energy sources. These initial and preliminary results of the REST study are not intended to represent new or startlingly different data from what has been documented in other papers and testimony. They do reflect the PAGENO="0044" 38 perspective which has been developing in the broad hydrogen com- munity and the baseline from which comprehensive and detailed tech- nology advancement plans can be generated. We expect to continue the second phase of this effort during fiscal year 1976. Using the general approach developed in the first phase, we will be exploring in considerable detail the definition of the teelmology advances actually required to assure that hydrogen is available, can be properly stored, and safely used. Many of the potential uses of hydro- gen, such as: Clean fuel, an energy storage device, fuel for fuel cells, and as a fuel for selected transportation modes, will be analyzed in much more detail than we have today. Our objectives are: First, to document the needs for hydrogen in as realistic a maimer as possible; second, to define the research and tech- nology advances which are mandatory t.o obtain the quantity of hydro- gen needed; and, third, to relate these in a comprehensive plan which could be implemented in the fiscal year 1977 period, if it actually ap- pears warranted. Our work will continue to be in direct cooperation with ERDA and in support of that Agency in developing national plans. I probably should mention here that we are studying some of the questions that have been raised earlier this morning. In our Energy Conversion Alternative study, which has been performed at Lewis for ERDA and for the NSF, we are looking at electrical power gen- eration modes from coal and coal-derived fuels. which include hydro- gen, particularly as it is used in fuel cells. We also have a. study in- volving high temperature process heat. which includes the thermal dissociation of water. This is part of the study referred to earlier that ~\Testinghouse and General Atomics are undertaking, and that is also being done for ERDA. Speaking personally, Mr. Chairman, I believe there is no question that we will eventually have some form of a "Hydrogen Economy." In fact,, and I guess by my standards, the present $1 billion per year in- dustry represents a good start. There is also no question in my mind but that the need for hydrogen will continue to increase in the future. I suspect. that we've just begun to appreciate the many uses for this unique element. I believe that. hydrogen, in addition to its uses in manufacturing, has a vital role in linking energy sources to energy consumers. I ques- tion whether the Nation can. or should, at this time firmly commit only to electricity as our prime means of energy communication in the future. I also know that we must be realistic in our expectations concerning the widespread availability of hydrogen as a means of energy distribu- tion. Instead of taking extreme positive or negative positions. we must conduct the studies and implement the technology advancement plans which will enable the Nation to most effectively obtain and use this unique and vital element. I'd be happy to answer any questions. and, again, I appreciate the opportunity to be here. Mr. MCCORMACK. Thank you very much. Jack for your testimony. and I want to say I particularly appreciate the very obvious coopera- tive effort that your are putting together with ERDA. PAGENO="0045" 39 I had a brainstorm as you were speaking, Jack. I'm curious to know-and I would like to ask both you and iDr. Kane this question- how close you are to achieving large volumes of high temperature gases in your R. & D. work? Rather than have that question dangling out in space, I'll tell you what I was speaking about. We just decommissioned the Peachbottom HTGR., which was, I believe, 40 megawatts. This was, I think, decom- missioned because it was no longer needed competitively in generating electricity. Here is a device close by that might be available, if we got to that general size of operation in the not too distant future. Is there any comment on this, has this any value at all? Are you exploring this kind of approach, or is it unrealistic, the time scale, as to the production of high volumes? Dr. SCHMITT. I'll defer, with a general answer, to Dr. Kane, Mr. Chairman. I would say that we feel that within the next year or so that research in high temperature materials is going to have to acceler- ate in many different areas, and in the use of high temperature gases, whether it's a closed cycl.e helium system for potential HTGR appli- cations, or whether it's understanding the high-temperature properties of hydrogen and materials associated with it. I'm not sure. Certainly, we are not prepared to detail what kind of program would be undertaken a year or two from now, but we think that is, in fact, an important part of our study, the REST study, to look at those kinds of programs and how they would fit into the na- tional R. & D. programs. Jim, did you have some comments? Dr. KANE. I can't give a nice, concise answer, but certainly if you look ahead to the future I'd say that we should try to replace fossil energies wherever possible. What can we replace them with in large quantities? And the first thing, the only thing, that looks like it's available in any kind of a. time schedule is nuclear. So, therefore, where can you use nuclear as a source of high temperature process heat? And if you look at the places where you can make big inroads, there's a number of electroprocesses that use a large amount of heat, and they would be amenable to being located close to the reactor, for instance. We had at least one meeting on that, an interagency meeting, which the old AEC, or maybe ER.DA sponsored, to look at just that question: What are the large consumers of coi'nmercial heat now sup- plied by fossil energy totally, and is there a chance that nuclear energy could replace this? I might point out that there's an intensive effort in Germany on the same subject, and I think it's something we all should keep in mind, that someda.y we have to look very hard at the use of coal and fossil energy, and can we switch this to more permanent energy sources. Now, my reaction to Peachbottom is that in general the big indus- trial consumers of heat demand a little higher temperature than the first generation of the gas-cooled reactors use. In other words, I think it would take an extension to perhaps the temperatures of the German Pebble-bed reactor before these really get interesting. I believe that's 900 centigrade. Mr. l\ICCORMACK. Yes. PAGENO="0046" 40 Dr. KANE. So I think in the future Peachbottom might be an inter- esting thing to solve some of the. problems involved with coupling, but as far as supplying a. high enough temperature for, say, reforming, or shift reactions, or some of the big consumers. Mr. Womack is here from R. & D. Would you mind if he spoke on that? Mr. MGCORMACK. I'd be delighted. Mr. ~TOMAcK. I think we spoke briefly on this about a year ago, about the possibility of using Peachbott.om for some potential experi- mental program. I believe, from some of the testimony this morning, and our view in that is, indeed, a quite promising area. The R. & D. t.hat needs to be done in high-temperature materials and components for the processes, still puts it some years off from effectively teaming and coupling proc- esses, teaming nuclear heat generation to hydrogen generation, and that the process development, particularly heat exchange develop- ment, can best be done in nonnuclear facilities during that period1 be- cause it's considerably easier. We do have a program, which has close cooperat.ioii with NASA and other part.s of the R.DA. in which we are trying to carry that for- ward in a way that will bring these things together some yea.rs hence, but retaining the Peachbottom reactor for tlia.t. purpose did not a.ppear to us to be the most effective way to do it. which is not to say we're not terribly interested in that. Mr. MCCORMACK. Thank you very much, because at least that means my question was iiot totally stupid. Mr. Thornton. Mr. THORNTON. Thank you, Mr. Chairman. Just a. couple of ques- tions, following t.he lines you just outlined. A couple of years ago we restored to the. NASA budget $10 million for continued research in several areas of nuclear power. That was Mr. }Iechler's committee, and now Mr. Fuqua's committee. Mr. HECHLER. The Thornton amendment. Mr. THORNTON. Yes: it was. We restored a. $10 million program, in- cluding such things as the high-temperature gas-cooled reactor, which was then beiiig conceived for space. propulsion purposes. Does this reactor have the temperatures necessary to be useful in the hydrogen process, or gasification process? Dr. SCHMIDT. Mr. Thornton, I'm going to have to supply that in- formation for the record, unless Mr. Ginter has that answer. The nuclear efforts that NASA has relative to space propulsion are in the. research side of the OAST. the Office of Aeronautics and Space Technology~ and we will ha.ve. to get. that information for you. Mr. THORNTON. It seemed to me. at. the time that this was done that there was a discussion that, this was a possibility, that the heat source from this unit. would be of a sufficiently high temperature to be useful in coal gasification~ and I would appreciate. tha.t being supplied. Dr. ScHMIrr. We will look into that. I do know that we've had some very interesting research going on in gas c.ore reactors and this kind of thing as a result. of this appropriation. We'll get. you sonic infor- mation for t.he record. Mr. THORNTON. Good. Thank you. [The information follows:] Question. Does this reactor have the temperatures necessary to be useful in the hydrogen process, or gasification process? PAGENO="0047" 41 Answer. Tinder NASA OAST, studies and initial experiments are being con- ducted on gas core reactors which contain the nuclear fuel in the gaseous or vapor state in contrast to conventional reactors (including the gas cooled reactor) that contain the nuclear fuel in form of solid fuel rods. Because of the gaseous or vapor state of the fuel in gas core reactors, such reactors could be operated over wide ranges of temperature, up to many thousands of degrees. Operation at the very high temperatures is a long range research goal of NASA, for space propulsion at high thrust and high specific impulse. The gas core reactor has the long term potential of meeting tl1e temperature requirements for hydrogen production and coal gasification. An additional ben- efit in this category of application would be in the area of steel production, particularly in regions that have plentiful ore but little coal. Mr. THORNTON. With regard to the use of natural gas as a source for hydrogen, we had a few moments ago the figure of an overall 36- percent efficiency, I believe, going from coal, to hydrogen, to electricity. Dr. Scinvrirr. Through the fuel cell. Mr. THORNTON. Through the fuel cell, correct. Can you tell me whether the dissociation of hydrogen from methane achieves similar efficiencies, or do you get that good a product when you use natural gas, or methane, or another source material? Dr. ScHMIrr. I suspect that the overall efficiency is somewhat less because of an extra step in there. We'll work with Jim to get that supplied for the record also. [The information requested follows:] Question. Can you tell me whether the dissociation of hydrogen from methane achieves similar efficiencies, or do you get that good a product when you use natural gas, or methane or another source material? Answer. Hydrogen, the present fuel required by fuel cells, can be more effi- ciently processed from methane than from coal. Therefore, fuel cells using meth- ane the fuel feedstock will have higher efficiencies than those that use coal. First generation fuel cells, which should be commercially available about 1980, have achieved efficiencies of 37 to 40% in demonstration tests using methane as the fuel. Advance fuel cell systems located near the consumer will achieve signifi- cantly higher efficiencies from fuel cell performance improvements and by utiliz- ing the waste heat. Mr. THORNTON. I would like to have that supplied for the record, be- cause I tend to agree with you that if natural gas can be efficiently converted to hydrogen, then this would be an efficient use of a diminish- ing natural resource, rather than consuming it in the process. But would the efficiency of the conversion be material? Dr. SCHMITT. Mr. Thornton, that's unquestionably one of the moti- vations behind the large industry effort, which is also supported by the gas utilities, in the development of a commercial fuel cell. In the in- terim stage, when we still are going to be dependent upon the use of natural gas prior to a large coal gasification industry developing, it does provide a more efficient use of that scarce fuel. I think we have to remember that the fuel cell does offer the possibility of having a va- riety of hydrocarbon fuels and hydrogen as the initial starting fuel, and that even though you develop now to use natural gas, it can be converted quite easily, with time, into other fuels. Mr. THORNTON. Jack, I want to thank you very much for your good testimony this morning. Dr. Sci-i~rrvr. Thank you very much, sir. Mr. MCCORMACK. And I want to thank you too, Jack. It was very nice of you to come. Dr. SOHMITr. It's a pleasure. Thank you, sir. Mr. MCCORMACK. Thank you. PAGENO="0048" 42 Our next witness is Dr. James Funk. dean of the College of Enoi- neering at the University of Kentucky. Dr. Funk, make yourself at home. Do you have anyone accompanying you that you would like to brino~ to the table with you? Dr. FUNK. No, I don't. Mr. MCCORMACK. OK. We welcome you to the hearing. Go right ahead and proceed in any way you wish. [The statement of Dr. Funk follows:] STATEMENT OF DR. JAMES E. FUNK, DEAN, COLLEGE OF ENGINEERING UNIVERSITY OF KENTUCKY Dr. FUNK. I would like to pass over ver quickly the market for hydrogen. Market questions are being addressed by a number of organ- izations, particularly the REST study. and will indicate that there is indeed a substantial market for hydrogen now and in the future for the production of ammonia, methanol, for petroleum hydro-treating, chemical processing. gasification and liquefaction of coal, and for en- ergy transmission and storage. Our partic~ilar activity at. Kentucky has been concerned since the imd-1960's with production techniques, and in order to introduce that program I would like to describe for you briefly the energy depot proiect conducted at the Allison Division of General Motors in the early sixties. This program was supported by the Army Reactors Branch of the AEC. It was an attempt to use portable nuclear power to relieve Arniy fuel logistics problems. The idea. was to produce a synthetic fuel on the site, using a portable liquid metal-cooled reactor. The requirement that the fuel be produced from readily available materials led very quickly to a consideration of hydrogen, ammonia, amid hydra.zine. Of those materials, ammonia was chosen as the pref- erable fuel. There had been experience in Germany with the. use of ammonia in buses, and there were some indications that ammonia could be used in an internal combustion engine without a great deal of trouble. In the course of doing those design studies it became very clear very quickly that the efficiency of prodll1cing the hydrogen was the limiting step in the overall efficiency of the fuel production system. Water electrolysis was used as a reference process for the production of hydrogen. The efficiency limitation in this case is the efficiency of producing electricity from thc thermal energy in the reactor. and we embarked on a thermochemical production project. which involved searching for chemical processes which would produce the hydrogen more efficiently froni the thermal power source than w-ater electrolysis. The idea was that if it is only possible to go from thermal energy to electricity at. say, 30-percent efficiency. why not search for a chemical process which will take time heat directly and dissociate the water. At that time we invented and evaluated a large number of thermo- chemical processes. We talked with other chemical engineering people around the country, and, in fact. performed a detailed preliminary design to determine the cost-benefit ratio of a four-step thermo-~ chemical process involving vanadium chlorides. PAGENO="0049" 43 The cost-benefit ratios were not attractive for the energy depot. scheme in total, and that project wa.s terminated. The program at Kentucky started in the mid-1960's under the sup- port of General Motors, and has subsequently been supported by NASA, Westinghouse, and, more recently, the Electric Power Re- search Institute. Cycle invention is the first, most appealing, and most attractive part of thermochemical studies, and we indulged ourselves in cycle in- vention to some extent. Mainly, however, we tried to focus our efforts on understanding the characteristics of chemical processes which would be efficient. The production of hydrogen from water is very similar to the pro- duction of electricity. The thermodynamic and fundamental aspects of the process are very similar. The characteristics of chemical reac- tions which will be efficient relate to considerations of Carnot efficien- cies in the conversion of thermal energy to useful work, or electricity. We have been cooperating in our program with the General Atomic Co., the Institute of Gas Technology. Westinghouse, the National Lab- oratories, including Argonne and Los Alamos, as well as some Euro- pean laboratories: the Euratom Laboratory at Ispra; the work bein done at the University of Aachen in West Germany; at Jfllich; an with people at the University of Tokyo in Japan. I would like to indicate my opinion of some of the important char- acteristics of the chemical processes, with the objective of outlining the necessary research and development programs which are required to develop an answer to this question in which we can have some confidence. In the first place, a thermochemical process is a series of chemical re- actions which, when written down and added up, simply sum to the decomposition of water. The work that's required to accomplish this process, or, if you will, the electricity required, depends on the changes in the thermodynamic properties of the chemical reactions. One of the real problems with the direct dissociation of water accom- plished simply by heating it up is that the work requirement does not decrease very rapidly as the temperature is increased. That's a result of the characteristic change in the entropy for that particular chemical reaction. If that characteristic is not attractive, the next thing to do is look for other reactions which do have appealing characteristic changes in thermodynamic properties~ and which also sum to the decomposition of water. It's very easy to write down chemical reactions which decompose water. What's more important to consider is the separation and recy- cling of the unreacted materials which occur in each of the reactions. As was pointed out earlier, some reactions are run at high tempera- tures and some are run at low temperatures. None of the reactions will proceed completely to the right hand side. They won't go to comple- tion. The products have, to be separated and recycled. The work that has to be supplied to accomplish the separation of the equilibrium mix- ture for the chemical re.actions is a very important consideration in determining the efficiency of the process. I cite as an example the fact that 30 years ago nitrogen and oxygen could be separated from air at an efficiency of 15 percent, and a very 62-332 0 - 76 - 4 PAGENO="0050" 44 detailed study of that process was prepared at that time which sug- gested that the efficiency might be increased to 20 percent, which, in fact, it is today. The same questions of separating the chemicals in the thermochemical process exist today. Another important factor has t~ do with internal heat recovery. As I mentioned, the thermochemical process operates at different temper- atures. This means that there are materials being heated and cooled, and the energy required to do that heating and cooling has got to be recovered inside the process in order to minimize the heat load on the primary energy source. Materials of construction has been mentioned as a very important problem. Another deals with catalysts. Many of the chemical reactions em- ployed will be catalytic in nature, and efficient catalysts must either be found or developed. The efficiency of the thermochemical process will vary with the op- erating temperature. There will be no chemical process which operates at ambient temperatures which will be more efficient than water elec- trolysis. The higher the temperature the more efficient will be the process, and, therefore. there is a need to develop high operating tem- peratures in order to develop high operating efficiencies. I believe there is a twofold research and development program which should be undertaken in thermochemical hydrogen production. The first part is analytical or theoretical. It's the kind of thing that's done with a. pencil and paper. It involves detailed thermodynamic studies, and I would like to make the analogy to the analysis of power- plants. The techniques for analyzing powerplants which produce electricity, either fossil fuel plants, nuclear plants, or fusion plants, are fairly straightforward. It's possible to do a lot of engineering and analysis on postulated power cycles without ever going into the labora- tory. That same situation does not obtain in thermochemical hydrogen generation. and in my opinion needs to be developed so that variations and changes can be quickly and easly evaluated. The evaluation procedure itself needs to be developed. We're very early on in the business of thermochemical hydrogen production, and evaluation procedures need to be developed and put into widespread use. Thermodynamic data banks are fairly scarce, and there are a number of questions about thermodynamic data. The chemists like to say that there is at least a 30-percent. chance of any data you pick out of the literature to use in any kind of an evaluation is wrong. Thats something that needs to be improved. Experimentally, we need a program of investigation of the. chemical reactions to determine, first of alL what the equilibrium conditions are, how fast the chemical reactions go, what. sort of catalysts might be needed, and. along with that program. material studies should be done to determine materials of construction. The effect of temperature will also have to be evaluated in the laboratory. These two programs, the theoretical or analytical program. and the experimental program, should be integrated. Those programs ought to be complementing and supplementing one another, so that we don't go off either doing all theoretical work or all experimental work. with- PAGENO="0051" 45 out making the connection. We should assure ourselves that what we are doing in the laboratory is, in fact, something that makes sense in theory, or that what we're trying to do theoretically is possible to do in the laboratory and on the commercial scale. Mr. Chairman, that completes my statement. Mr. MCCORMACK. Thank you, iDr. Funk. Your statement is very much appreciated. I have a couple of quick questions for you. Is there open communication, including the international commu- nity, on thermochemical processing for hydrogen production? Dr. FUNK. I think the answer to that question in general is yes. The problem comes, naturally, with commercial organizations developing proprietary processes, and in that case there is some difficulty in get- ting information interchanged. Mr. MCCORMACK. Do you feel that you are able to keep up-to-date on this? Dr. FUNK. Yes; more or less. Mr. MCCOR1\IACK. So that if someone is developing a new system in Yugoslavia you are going to know about it? Dr. Fuxic. There was recently a seminar in Paris, France, on ther- mochemical hydrogen processes, and there were some 10 to 13 countries involved. There was generally quite goo'd communication on the kmcl of work that's going on. I think it's going to be more difficult as the number of organizations involved in this business increases. Mr. MCC0RMACK. Have there been any conferences on the subject in this country involving universities and industry during recent months, in the last year or so? Dr. FUNK. Oh; yes, indeed. I guess there have been six, six or seven, in the last couple of years. Mr. MCCORMACK. So there is good communication in this country and open literature, at least, is available to all? Dr. FUNK. Yes. Mr. MCCORMACK. And whatever forward movement that exists is more or less uniform in the various groups? Dr. FUNK. Yes. I believe there will be published shortly a Journal of Hydrogen Energy, which, hopefully, will bring together the infor- mation and identify the organizations and the work they're doing. Mr. MCCORMACK. Would you care to make any projections-for any given process at any given time in the future? Dr. FUNK. I think that we're probably talking a number like 5 years to a pilot plant, and to a demonstration plant it's; very difficult to speculate. Mr. McCoR~rAcK. Five years to a pilot plant. And then do you have any particular belief as to what process will be found? Dr. FUNK. No; I don't. I think there probably will emerge two or three very attractive processes. They're not clear to me at this time. We're attempting now to do for EPRI a preliminary design and economic study, and the first task in that project is to choose a process. Mr. MCCORMACK. Thank you. Mr. Hechler. Mr. HECIILER. Thank you, Mr. Chairman. Dr. Funk, I would just like to ask two technical questions. PAGENO="0052" 46 In our discussions in the hearings on helium I asked whether or not it would be. possible to get helium from synthetic natural gas-whether it would be possible, even though it takes hydrogen to produce. In the process of coal gasification could you then obtain any hydrogen out of it? Is that true.? Di. FUNK. Hydrogen could produce some coal-derived SNG in the same way that it's produced now, from naturally recoverable methane. Mr. HECHLER. What is the relation then of the amount of hydrogen it takes in your coal gasification to what you could get out of your product.? Dr. FUxi~. There is roughly one atom of hydrogen for every atom of carbon in the coal. So if that coal is going to be transformed into sub- stitute. natural gas, into methane, three atoms of hydrogen have to be found somewhere to add to that carbon. Now, the irocess today will produce the hydrogen from water and the carbon in the coal, so some of the carbon will be used up. An alter- nate source of hydrogen from, say, a thermochemical process, would conserve carbon to that extent, which is quite considerable. There wouldn't be, that I can see, much point, in then producing hydrogen from the SNG- that was just produced from the coal. I think if the objective is hydrogen from coal there are processes which may be similar to. for instance, the Koppers Totzek process, which might produce, the hydrogen more directly. I'm not sure I answered your question.. Mr. HECHLER. Yes; you did. Could you spell out more specifically the relative amounts of hy- drogen that would be obtained from the different qualities of coal? Is there any difference in the coal. in terms of the ash, or sulfur, or pure content of coal, as to how much hydrogen can be produced? Mr. FUNK. That would be determined almost entirely by the carbon content of the coal. High grade bituminous coal, because it has more carbon, would produce more hydrogen than will a semi-bituminous coal or a. lignite. Mr. HECHLER. What about within the categories of bituminous coal that are above the lignite area? There are wide variances, you know, in the quality. Dr. FUNK. Yes. Mr. HECHLER. I just. wondered if the. carbon content is the sole determining factor. Dr. Fnxic I think the carbon content is the primary determining factor. Mr. HECIILER. I understand you cannot. get it from anthracite. Is that. right.? Dr. Fuxic. I don't. think I would be willing to say you can't get it from anthracite. I think you could gasify anthracite to produce a syngas from which hydrogen could be produced. From the carbon, t.he hydrogen could be produced. Mr. HECIILER. Thank you. Mr. Chairman. Mr. MCCORMACK. ~lr. Fuqua. Mr. FUQUA. Thank you. Mr. Chairman. I am interested in what would be the relative cost of hydrogen pro- duction by thermochemical processes as compared to the conventional processes by which we get it today? PAGENO="0053" 47 I am thinking primarily about ammonia, of which we are in very short supply in this country, particularly for agricultural purposes. How would the cost compare? Dr. FUNIc. My impression is that with natural gas prices as they are today there will be no cheaper way to produce hydrogen. The methane-steam reforming process is well-developed. The cost is very well known. If the feedstock costs 70 cents a million British thermal units, the hydrogen will probably come at a number like $1.30, something like that. In water electrolysis, the maj or determinant of the cost is the cost of power, and in that event we may be talking about $3 or $4 a million Btu's. The cost of hydrogen from thermochemical- Mr. FUQUA [interrupting]. And how much water are we talking about using? That also is a critical problem in some areas, and getting more critical in others. Dr. FUNK. Water as a feedstock for hydrogen production I don't think is a big problem. But the cost of hydrogen production by thermochemical processes is not known. It's only very recently that cost estimates are being made, both here and in Europe, and there is some feeling that this is not the right time to be doing those kind of cost estimates because the processes are still too ill-defined. Mr. FUQUA. Thank you, Mr. Chairman. Mr. MCCORMACK. Thank you, Mr. Fuqua. Mr. Thornton. Mr. THORNTON. Thank you, Mr. Chairman. I have no questions, but I want to compliment the witness on his very interesting presentation. Di. FUNK. Thank you. Mr. MCCORMACK. Now let me ask you one more question, Dr. Funk. Perhaps I missed a point, but I was going to ask about your pro- jection for the ultimate energy efficiency of producing hydrogen by thermochemical processses. What is your guess? Dr. FUNK. I would prefer not to make a guess at that number. It goes like this: The process gets invented, and you calculate the efficiency at 65 percent, and then you begin to do some very preliminary sort of engineering work, considering questions of recycling, and separating, and it will drop to 50 percent. Then, the much more de- tailed kind of analysis will produce a number like 35 percent. I think it's just too early to estimate what that ultimate efficiency will be. but I think we can say this: If it isn't 40 percent, then we won't have thermochemical processes, unless they are very much cheaper in terms of capital costs than water electrolysis, because water electrolysis will probably deliver efficiencies in the 35- to 40-percent range. Mr. MCCORMACK. But it might also depend on whether or not one used heat directly from HTGIR's or accepted the penalty of 40 percent to go to electricity, followed by transfer of the electrical energy. Dr. FUNK. No; the efficiencies I mentioned are all on the same basis. The efficiencies I referred to went back to the thermal reactor power. Mr. McCoR~rAcK. I see. So, then you are not yet ready to project the cost per Btu, is that right? Dr. FUNK. That's right. Mr. MCCORMACK. So you are really just getting started. Dr. FUNK. Yes, I think that's the situation. PAGENO="0054" 48 Mr. MCCORMACK. Well, at least we are doing that. Perhaps this hear- ing, and the one that comes up next Thursday at 8 o'clock in room 2318 will continue the discussions. I want. to thank you all very much. rllhe meeting is adjourned. [Whereupon. the subcommittee was adjourned at 9 :48 a.m., to re- convene at 8 a.m.. on Thursday. June 12. 1975.] PAGENO="0055" HYDROGEN THURSDAY, JUNE 12, 1975 HoUsE OF REPRESENTATIVES, COMMITTEE ON SCIENCE AND TECHNOLOGY. SUBCOMMITFEE ON ENERGY RESEARCH, DEVELOPMENT AND DEMONSTRATION, Washington. D.C. The subcommittee met., pursuant to adjournment~, at 8 a.m., in room 2318, Rayburn 1-louse Office Building, Hon. Mike McCormnck, chair- man of the subcommittee, presiding. Mr. MCCORMACK. The meeting will come to order. I should like to welcome you to this second hearing on the potential for hydrogen to play a significant role in our energy economy of the future. As I mentioned on Tuesday, hydrogen is not a new source of energy, but rather an intermediate form like electricity. As a gas with properties somewhat similar to natural gas, it can play an important part in meeting our energy needs in the years ahead. The key to using hydrogen is, of course, economical l)roduction and safe transmission and utilization. This means that new technology is required. The new technology will build on that (leVeloped in the past by NASA, which testified on Tuesday, the Defense Department, which appears today and other agencies and private industry. The utilities have also given much thought to the opportunities of- fered by the hydrogen economy. We will hear from two such groups today. [Mr. McCormack's welcoming remarks for Navy witnesses follow:] Mu. McCon~rAcK's WELCOMING REMARKS FOR NAVY WITNESSES Unfortunately. Mr. Goldwater is unable to be with us this morning because of a commitment out of `town. If he were here, I am certain that he would take this opportunity to welcome all of you and to thank you for your participation in these hearings. Beyond that, though, I am sure that Mr. Goldwater would also take this opportunity to commend the farsightedness of the Navy in focusing early and very effectively on this Nations acute need for a well-coordinated and well-integrated approach to energy R. & D., particularly the coordination and integration of energy R. & ID. between the Defense Department and our civilian agencies. As you are aware, this subcommittee has oversight jurisdiction for specified energy R. & D. throughout the Federal Government. Mr. Goldwater and I both intend to closely follow the activities of the Navy and the other services in energy R. & D. I know that he is considering recommending hearings later in the year to review these activities. In that regard, we have recently been encour- aged by the timely £O solar heating and coolh~g demonstration units planned at Defense Department bases (20 Navy) across the country which Admiral Hart testified about here last month. (49) PAGENO="0056" 50 We would certainly encourage the continued and enthusiastic participation of the Navy and the Defense Department in that and other national energy R.. & D. programs, consistent, of course, with departmental mission constraints and re- quirements. The Defense Department. a~ the largest single consumer of energy in the Nation (consuming approximately 5% of the Nation's energy during peacetime), and undoubtedly the consumer with the largest single fuel bill in the United States (approximately five billion dollars in this fiscal year) certainly has a significant role to play in energy research. In fact, DoD, with its aircraft.. ground vehicles, housing, remote bases, ships, etc. represents a microcosm of the country's energy requirements and it can serve well as a cooperative partner with our civilian agencies in addressing the multitude of energy research issues. On behalf of Mr. Goldwater, I should like specifically to commend Com- mander Paul Petzrick and Dr. Pete Waterman for their efforts in energy re- search. Mr. Goldwater and this subcommittee, as you know, have recently been joined by our minority staff counsel, who has brought to the Congress a very deep respect and a very great enthusiasm for your organization's activities in energy research and development. As a result, we are becoming increasingly aware and appreciative of those activities both within the Defense Department and their cooperation with the civilian agencies which we oversee. Commander Petzrick. I personally recall our informal discussion in my office last fall. My recollection is that we focused then on the need for accelerated research in advanced concepts across the entire spectrum o energy sources, technologies and applications. That is our focus this morning with regards to hydrogen and really the overall focus of this subcommittee, where are we now in our energy technology and w-here must we go as a nation to achieve our national goals of long range energy sources which are economical, dependable, reliable and secure. I note, Commander Petzrick. that you are a Civil Engineering Corps officer and I am certain that Mr. Goldwater would comment on his pride regarding the fine energy research activities at the Navy's civil engineering laboratory at Port Hueneme, He has worked closely with CEI and he has a particular interest in the energy conservation activity there, energy conservation being a major area of interest of this subcommittee also. Finally. I also note as an aside, Commander. that we are 1)0th in the energy reporting business-you, with your fine energy H. & D. SITREP for the Defense Department, w-hich we here read weekly, and this subcommittee, w-ith the energy news notes which we periodically publish here to keep all the members abreast of energy developments. We welcome you here this morning and, on behalf of both myself and Mr. Goldw-ater. wish to commend you for your outstanding contributions in energy R. & D. Mr. MCCORMACK. Our witnesses today are Comdr. Paul Petzrick, Director. Navy Energy. Research and Development Office, Head- quarters, Naval Materiel Command. He is accompamed by Dr. Peter `Waterman, Special Assistant. Office of the Assistant Secretary of the Navy. Research and Development. Also with him is Mr. Homer Car- hart of the Naval Research Laboratory and Mr. Carl Hershner, Naval Ship Research and Development Center. We will then hear from Dr. Derek P. Gregory, Director, Energy Sys- tems Research, Institute of Gas Technology and Mr. Sidney H. Law~ Director of Research of Northeast Utilities. He will be accompanied by Dr. Michael Lotker. a scientist on advanced energy conversion at Northeast Utilities. Commander Petzrick, you may come forward and bring your col- leagues to the front. table. If you wish, we can insert your entire state- ment in the record at this point. Then you can speak from it or summarize, whichever you prefer. PAGENO="0057" 51 STATEMENT OF PAUL PETZRICK, DIRECTOR, NAVY ENERGY, RE- SEARCH AND DEVELOPMENT OFFICE, HEADQUARTERS, NAVAL MATERIEL COMMAND; ACCOMPANIED BY DR. PETER WATER- MAN, SPECIAL ASSISTANT, OFFICE OF THE ASSISTANT SECRE- TARY OF THE NAVY, RESEARCH AND DEVELOPMENT, AND HOMER CARHART OF THE NAVAL RESEARCH LABORATORY AND CARL HERSHNER, NAVAL SHIP RESEARCH AND DEVELOPMENT CENTER Commander PETZRIOK. We have this statement for summary and insertion. Then I will make some remarks at this morning's meeting. Mr. MCCORMACK. Without objection, the complete statement will be inserted. [The complete statement of Comdr. Paul Petzriek, TJSN, is as follows:] STATEMENT OF COMMANDER PAm~ PETZRICK, CEO, TJSN (This summary highlights some of the Navy's recent research and development activities to evaluate hydrogen as a potential alterna- tive to fossil fuels in naval applications.) In mid-1973, at the request of Dr. Peter Waterman, Special Assistant, Office of the Assistant Secretary of the Navy (Research and Development), the Naval Research Laboratory (NRL) formed a hydrogen panel, with Dr. Homer W. Carhart as chairman, to conduct a special study of hydrogen as a Navy fuel. Both Dr. Waterman and Dr. Carhart are present and will be available to answer question's. The results of the panel's work are contained in NRL Report 7754, Hydrogen As a Navy Fuel, Naval Research Laboratory, June 1974. A copy of this report is submitted and additional copies can be made available. The conclusions of the study are that hydrogen has many desirable properties as a fuel. It can be burned efficiently in all burners and engines in widespread use today. Furthermore, it is a superior material for fuel cells with potential for efficiencies higher than conventional types of combustion. A high heat of combustion is the property that makes hydrogen attractive. However, the low density of liquid hydrogen negates much of the advantage obtained by the heat of combustion, particularly for volume-limited vehicles. Thus, the use of hydrogen in major ships and carrier aircraft is not promising. Special applications, such as fueling small, weight-limited craft, may be practical. liemote naval facilities, if located near environmental sources of energy, could use the hydrogen fuel storage and transport idea. Hydrogen is not a prime fuel, but must be produced by putting energy into chemical reactions. The most promising reactions today are based on fossil fuels, with coal having long-term resource potential. An expected trend to large-scale nuclear power generators should make the electrolysis of water the favored H2 production process in the long term. The hazards of gaseous hydrogen are greater than those of most combustible gases because of the wide flammability limits aad the high flame velocity. Con- siderable experience with hydrogen-containing gases (town gas) has shown that suitable handling techniques are available. Experience w-ith liquid hydrogen is limited, however, an explosion hazards must be examined in detail. Storage techniques for liquid hydrogen are not satisfactory, and high boiloff losses would be experienced with containers that are satisfactory for liquefied natural gas. Hydrogen tank desigu for irregular shapes, as on ships and aircraft, is inadequate. PAGENO="0058" 52 The cost of hydrogen between 1990 and 2000 will be several times that of current Navy fuels for equal amounts of energy. However, the present trend in crude oil price increases coupled with the decreasing oil reserves-to-production ratio indi- cates that 112 will not be at as large an economic disadvantage tl1en as it is today. The cost of 112 should not be a deterrent to its use in the Navy if system perform- ance shows significant advantages. Concurrently with NRLs overview of hydrogen's general potential as a Navy fuel, the naval ship research and development centers Annapolis laboratory (NSRDC/A), with support from the Defense Advanced Research Projects Agency (DARPA), undertook a more detailed study of the mission capabilities of Hydro- gen-Fueled Naval Force Elements and also an assessment of the state of hydrogen technology for the purpose of identifying any research and development that would be necessary for demonstrating the military effectiveness of hydrogen- fueled vehicles. The project engineer for NSRDC's study contracts is Mr. Carlton Hershner, Sr., who is present and will be available to answ-er questions. The assessment of the state of hydrogen technology is being compiled by a team of investigators at the Stevens Institute of Technology. Hoboken, New Jersey. A summary of their work through August 1974 is contained in their Report, Hydrogen As A Fuel, R. F. M. McAlevy, III, et al, NTIS No. AD-787 484/5WE, Stevens Institute of Technology, Hoboken, New- Jersey, August 1974. A copy of this report is submitted and additional copies from the Defense Documentation Center can be made available. The report summarizes the generation of hydrogen by electrolysis, coal gasifica- tion, and thermochemical proceses. It states that highly efficient electrolyzers are required if large-scale electrolysis of 112 is to be economically feasible, owing to the ever-increasing cost of electricity. A review of current technology reveals that much of the present effort in electrolyzer design is directed tow-ard achieving the high levels of efficiency that are theoretically possible. Based on the information available, however, it was impossible at this time to discern one that is uni- versally superior. Coal gasification appears practical for near-term and intermediate-term 112 generation in the U.S.A. because of this country's large coal reserves and the growing w-orld-wide shortage of petroleum. Tw-o proven processes are already in commercial use in other countries, the Lurgi process and the Koppers-Totzek process (the latter being preferred for high 112 yields). How-ever, neither process is currently used in this country. Instead, IL is generally produced by steam re- forming of natural gas and petroleum liquids, apparently as a result of economic constraints. Coal gasification processes will have no significant impact on H2 generation in this country for 5 years or so. In the long term, 112 generation by thermochemical water-splitting processes appears promising, using nuclear heat sources. For the chemical processes pro- posed to date, sufficient fundamental information does not exist to permit selec- tion of the most promising candidates. Generally. the thermochemical processes involve fewer reactions and higher efficiencies w-hen higher maximum tempera- ture heat is available. Thus, the thermochemical 112 generation w-ill be feasible with high-temperature gas-cooled reactors (temperature of coolant betw-een about S0O° C. and 10000 C) and probably is not feasible with the liquid metal fast- breeder reactor (coolant temperature between about 4500 C and 575°C). The report also surveys the w-ork done by other investigators w-ith hydrogen- fueled engines. It deals wih fundamental relationships derived between fuel properties and engine-performance parameters: operating experiences with 112- fueled, reciprocating, spark-ignition engines are also comprehensively summarized. Together. these provide a rational basis for evaluation of 112 as a fuel. Numerous comparisons are made between 112 and gasoline use: it is shown that 112 operation allows high efficiency and low- pollutant emissions along w-ith a control possibility ("quality control") which is impractical w-ith gasoline. However, to gain these advantages of H2 operation, engines must be operated fuel-lean at approximately one-half the stoichiometrically correct fuel/air mixture ratio. Under such condi- tions, the chemical-energy content of the lean fuel/air mixture is reduced, sub- stantially penalizing the work (or power) output of the engine. Conventional supercharging or cylinder fuel injection can compensate for such a pow-er penalty w-hile maintaining the advantages of 112 use. From many view-points. 112 is an attractive alternative to gasoline and other hydrocarbons as engine fuels. Hydro- gen use deserves further investigation both experimentally and analytically. The study of the mission capabilities of hydrogen-fueled Naval forces is being conducted by the General Electric-Tempo, Center for Advanced Studies in Santa PAGENO="0059" 53 Barbara, California. Their findings are contained in the report by B. Berkowitz, et al, Alternative, Synthetically Fueled Navy Systems: Force Element Missions and Technology, DDC No. AD/B-001 401L, General Electric Company-Tempo, November 1974. A copy of this report is submitted and additional copies can be made available. The objective of this study is to determine the effects that the use of hydrogen, and synthetic fuels derived from hydrogen, would have on the design and per- formance of Navy ships and aircraft in assigned missions. The term "synthetic fuel," as used here, applies to those fuels which could be produced aboard a factory ship at sea or in a transportable, forward-based manufacturing complex having some primary energy source such as nuclear, solar, etc. The ships which have been selected for this study represent a range of types which might be found in use by the Navy between the present and the end of this century. They include hydrofoils, a surface effect ship, and displacement type hulls ranging from 230 to 55,000 long tons in weight. The aircraft include a vertical-, or short-, take-off and landing (V/STOL) type as well as a carrier- based attack (VA) type. Helicopters and other Navy types of aircraft have not been investigated in detail, but their estimated fuel requirements have been included in the analyses of those ship types which carry aircraft. The ships and aircraft modeled in the study represent generic rather than specific designs. The primary emphasis is on the comparison of fuels rather than ship designs. From the wide spectrum of synthetic fuels which could be produced aboard a factory ship, hydrogen obtained by decomposition of water is. of primary inter- est. But, ammonia and hydrazine are also considered because they can be made from hydrogen and nitrogen, which can be obtained from air separation. Methane and methanol are also considered for the possibility that a source of carbon might be available with which to produce them from hydrogen. And finally, the methylamines have been considered since they can be made from methanol and ammonia. It is a general characteristic of the synthetic fuels that their `volumetric energy densities are smaller than those of petroleum-derived fuels. Consequently, for a synthetically fueled vehicle to achieve equivalent operating ranges, a greater volume must be allocated for fuel storage, resulting in increases in both structural weight and hydrodynamic and/or aerodynamic drag. Thus, within constant total weight constraints, there is a limit to the extent to which fuel storage volume can be increased and this leads to possible degradation in mis- sion performance. The method of comparing each of the synthetic fuels in each of the vehicles, therefore, is to establish a baseline design fueled with the Navy's standard Diesel, Fuel Marine (DFM). Then, by varying dimensions, within certain con- straints, to maximize the weight of syiithetiv fii~1, the speed-power-fuel con- sumption characteristics of the modified design are calculated. From the fuel consumption data and a synthesized mission profile, the unrefueled range of each vehicle modified for each synthetic fuel is determined and compared. The findings of the study are summarized as follows: Ships modified to operate on hydrogen, methane, or methylamines achieve ranges comparable to those of the same ships operating on diesel fuel marine. Ships modified to operate on hydrogen, methane, or methylamine achieve ap- proximately twice the range of the same ships modified to operate on methanol, ammonia, or hydrazine and `consequently would have to be refueled only half as often. The dynamic lift ships, hydrofoils, and surface effects ships achieve a greater range performance when using hydrogen than for DFM or any of the other synthetic fuels. For displacement hulls in the 3,000 to 6,000 ton class, the ships modified to operate on hydrogen and methane achieve `approximately the same range per- formance as that of the DFM-fueled ship. For the 14,000-ton and a new concept 55,000-ton aircraft-carrying ships, greater range performance is achieved for the DFM-fueled and methane-fueled ship than for the hydrogen-fueled ship. For the 40,000-ton amphibious assault support ship, the range performance is approximately the same for the ship operating on either hydrogen, DFM, or methane. Carrier-based aircraft modified to operate on hydrogen and methane, and assuming nonaccelerated flight, w-ould be expected to suffer approximately a 10 PAGENO="0060" 54 percent range degradation for hydrogen and a 5 percent degradation for methane. The use of the other synthetic fuels would result in greater degradation. The results of this investigation indicate that liquid hydrogen and liquid methane used in dimensionally modified ships and aircraft are potentially equivalent to conventional fuels in mission performance capability. However, if the carbon to produce methane must be transported from a continental land base to the factory ship as coal, this logistic burden is within 1.5 percent of DFM tonnage required for direct use. Therefore. liquid hydrogen remains as the most promismg synthetic fuel alternative. The study leaves unanswered, however, the question of whether optimum design from first principles would result in significantly different vehicle de- signs and performance parameters. The research and development, areas found to be critical to the improved potential of cryogenically fueled naval vehicles are fuel storage and handling and overall system design. In the area of fuel storage, the metal hydrides being investigated by other agencies appear to impose too great a weight penalty for beneficial application to naval vehicles. In addition, the dissociation rates may not be acceptable for application in power systems with high demand rates. Molecular hydrogen, as a cryogenic liquid, appears to be the most desirable form for storing hydrogen although its requirement for a high lJerforma1~ce insulation is a disadvantage for naval designers. Unlike the aircraft application where relatively short mission times at high consumption rates permit the use of less efficient solid insulations, shipboard applications will require the low-, or no-loss storage of large quantities of liquid hydrogen for extended periods of low consumption rate; this requires the application of higher efficiency vacuum- type insulations. These not only add to the volume disadvantage of hydrogen, but also require additional structure which invokes a weight penalty. Conse- quently, more development of better insulation systems and structural designs for the weight-critical dynamic-lift will be required. The hazards of hydrogen are fairly well known as the result of investigations undertaken for aerospace programs of the 1960's. However, the combat environ- ment imposes new unknowns which must be studied in greater depth before mili- tarily effective, hydrogen-fueled systems can be designed. For example, the stor- age of hydrogen in the hull of a ship can bring together all of the undesirable conditions of leakage, sources of ignition, and confinement under which hydrogen will detonate. When the risks of hostile weapons effects are added to this, the design of hydrogen systems for the combat environment becomes formidable. As the result of continuing study and liaison with other agencies and organiza- tions investigating the `hydrogen economy," it appears that hydrogen could be used effectively in some new designs of the Navy's weight critical surface ships and in special applications such as deep-diving submersibles, shore installations, etc. The design and development of combat systems, however, will require more extensive investigation. No matter what potential is assumed for the hydrogen economy, the funda- mentals of hydrogen technology will assume greater importance in future fuels. It is therefore recommended that those agencies responsible for development of basic fuel technology give extensive consideration to hydrogen. Their work will provide important background for our continued assessment of hydrogen in mili- tary applications. Commander PETZRICK. Our statement is a summary of the highlights of the Navy's research and deve~opinent activities to evaluate hydrogen as a potential alternative to fossil fuels in naval applications. Mr. Chairman, our evaillation consists of three studies, one done by the Navy Research Laboratory and two studies done by private contractors. I will discuss this matter briefly. In mid-1973, at the request of Dr. Peter WTaterman, the Navy Research Laboratory formed a hydrogen panel with Dr. Carhart as chairman. Dr. Carhart is here this morning to answer questions. The results of the panel's work are contained in NRL Report 7Th4. "Hydrogen as a Navy Fuel." Naval Research Laboratory~ June 1974. A copy of this report is submitted and additional copies can be made available. (See appendix IL p. 673.) PAGENO="0061" 55 The conclusions of the study are that hydrogen has many desirable properties as a fuel. It can be burned efficiently in all burners and engines in widespread use today. Furthermore, it is a superior material for fuel cells with potential for efficiencies higher than conventional types of combustion. A high heat of combustion is the property that makes hydrogen at- tractive. However, the low density of liquid hydrogen negates much of the advantage obtained by the heat of combustion, particularly for volume-limited vehicles. Thus, the use of hydrogen in major ships and carrier aircraft is not promising. Special applications, such as fueling small, weight-limited craft, may be practical. Remote naval facilities, if located near environmental sources of energy, could use the hydro- gen fuel storage and transport idea. The hazards of gaseous hydrogen are greater than those of most combustible gases because of the wide flammability limits and the high flame velocity. Considerable experience with hydrogen-containing gases-town gas-has shown that suitable handling techniques are available. Experience with liquid hydrogen is limited, however, and explosion hazards must be examined in detail. Storage techniques for liquid hydrogen are not satisfactory, and high boiloff losses would be experienced with containers that are satis- factory for liquefied natural gas. Hydrogen tank design for irregular shapes, as on ships and aircraft, is inadequate. The cost of hydrogen between 1990 and ~000 will be several times that of current Navy fuels for equal amounts of energy. However, the present trend in crude oil price increases coupled with the decreasing oil reserves-to-production ratio indicates that H2 will not be at as large an economic disadvantage then as it is today. The cost of H2 should not be a deterrent to its use in the Navy if system performance shows significant advantages. Concurrently with NRL's overview of hydrogen's general potential as a Navy fuel, the Naval Ship Research and Development Center's Annapolis laboratory-NSR.DA/A-with support from the Defense Advanced Research Projects Agency-DARPA-undertook a more detailed study of the mission capabilities of hydrogen-fueled naval force elements and also an assessment of the state of hydrogen tech- nology for the purpose of identifying any research and development that would be. necessary for demonstrating the military effectiveness of hydrogen-fueled vehicles. The project engineer for NSRDC's study contracts is Mr. Carlton Hershner, Sr., who is present, and will be available to answer questions. The assessment of the state of hydrogen technology is being coin- piled by a team of investigators at the Stevens Institute of Technology, Hoboken, N.J. A summary of their work through August 1974 is con- tained in their report, Hydrogen as a Fuel, R. F. M. McAlevy III, et cetera, NTIS No. AD-787 484/5WE, Stevens Institute of Technology, Hoboken, N.J., August 1974. A copy of this report is submitted and additional copies from the Defense Documentation Center can be made available. The report summarizes the generation of hydrogen by electrolysis, coal gasification, and thermochemical processes. It states that highly efficient electrolyzers are required if large-scale electrolysis of H2 is to, be economically feasible, owing to the ever-increasing cost of elec- PAGENO="0062" 56 tricity. A review of current technology reveals that much of the pres- ent effort in electrolyzer design is directed toward achieving the high levels of efficiency that are theoretically possible. Based on the infor- mation available~ however~ it was impossible at this time to discern one that is imiversallv superior. The study of the mission capabilities of hydrogenfueled naval forces is being conducted by the General Electric-TEMPO, Center for Advanced Studies, in Santa Barbara. Calif. Their findings are con- tained in the report by B. Berkowitz. and others, "Alternative, Syn- thetically Fueled Navy Systems: Force Element Missions and Tech- llology%" DDC No. AD/B-OO1 401L. General Electric Co.-TEMPO, November 1974. A copy of this report is submitted and additional copies can be made available. The objective of this study is to determine the effects that the use of hydrogen. and synthetic fuels derived from hydrogen, would have on the design and performance of Navy ships and aircraft in assigned missions. The term "synthetic fuel," as used here. applies to those fuels which could be produced aboard a factory ship at sea or in a transport able, forward-based manufacturing complex having some primary energy source such as nuclear, solar, et cetera. From the wide spectrum of synthetic fuels which could be produced aboard a. factory ship. hydrogen obtained by decomposition of water is of primary interest. But. ammonia and hydrazine are also con- sidered because they can be macIc from hydrogen and nitrogen. which can be obtained from air separation. Methane and methanol are also considered for the possibility that a source of carbon might be avail- able with which to pi~ocliice them from hydrogen. And finally, the methylamines have been considered since they can be made from met- hanol and ammoma. It is a general characteristic of the synthetic fuels that their volu- metric. energy densities are smaller than those of petroleum-derived fuels. Consequently. for a synthetically fueled vehicle to achieve equi- valent. operating ranges. a greater volume must be allocated for fuel storage. resulting in increases in both structural weight and hydro- dynamic. and/or aerodynamic. drag. Thus. within constant total weight constraints, there is a limit to the extent to which fuel storage volume can be increased and this leads to possible degradation in mission performuamice. The findings of the study are summarized as follows: Ships modified to operate on hydrogen. methane, or methylamine achieve ranges comparable to those of the same ships operating on diesel fuel marine. Ships modified to operate on hydrogen, methane, or methylamine achieve approximately twice the. range of the same ships modified to operate on methanoL ammonia. or hydlrazine and consequently would have to be refueled only half as often. The dynamic lift ships. hvdrofoils and surface effects ships achieve a greater range performance when using hydrogen than from DFM or any of the other synthetic fuels. Carrier-based aircraft modified to operate on hydrogen and met- hane. amid assuming nonacceleratecl flight. would be expected to suffer approximately a 10-percent. range degradation for hydrogen and a 5 PAGENO="0063" 57 percent degradation for methane. The use of the other synthetic fuels would result in greater degradation. The results of this investigation indicate that liquid hydrogen and liquid methane used in dimensionally modified ships and aircraft are potentially equivalent to conventional fuels in mission performance capability. However, if the carbon to produce methane must be trans- ported from a continental land base to the factory ship as coal, this logistic burden is within 15 percent of DFM tonnage required for direct use. Therefore, liquid hydrogen remains as the most promising synthetic fuel alternative. The study leaves unanswered, however, the question of whether optimum design from first principles would result in significantly different vehicle designs and performance parameters. The research and development areas found to be critical to the improved potential of cryogenically fueled naval vehicles are fuel stora.ge and handling and overall system design. In the area of fuel storage, the metal hydrides being investigated by other agencies appear to impose too great a weight. penalty for bene- ficial application to naval vehicles. In addition, the dissociation rates may not be acceptable for application in power systems with high demand rates. Molecular hydrogen, as a cryogenic liquid, appears to be the most desirable form for storing hydrogen although its requirement for a high performance insulation is a disadvantage for naval designers. Unlike the aircraft application where id atively short mission times at high consumption rates permit the use of less efficient solid insula- tions, shipboard applications will require the low-, or no-loss storage of large quantities of liquid hydrogen for extended periods of low consumption rate; this requires the application of higher efficiency vacuum-type insulations. These not only add to the volume disadvan- tage of hydrogen, but also require additional structure which invokes a~ weight penalty. Consequently, more development of better insula- tion systems and structural designs for the weight-critical dynamic- lift ships will be required. As a result of continuing study and liaison with other agencies and organizations investigating the hydrogen economy, it appears that hydrogen could be used effectively in some new designs of the Navy's w-eight. critical surface ships and in special applications such as deep- diving submersibles, shore installations. et cetera. The design and development of combat systems, however, will require more extensive investigation. No matter what potentia.l is assumed for the hydrogen economy, the fundamentals of hydrogen technology will assume greater im- portance in future fuels. It is therefore recommended that those agen- cies responsible for development of basic fuel technology give exten- sive consideration to hydi~ogen. Their work will l)iOvide important background for our continued assessment of hydrogen in military applications. Now. Mr. Chairman, that concludes the summary of our prepared statement. I would add a personal comment on reviewing programs of other agencies. I want to identify some key thrusts. I would hope that significant work to reduce the cost of producing hydrogen would PAGENO="0064" 58 result. This would have an immediate payoff to reduce the cost of fertilizer. Second. we have. attempted to burn hydrogen in existing combustors and engines. The program needs a key thrust for the development of a combustor that is exclusively designed and optimized to burn hydrogen. Mv team is available at this time to answer your questions. Mr. McC0R3IAcK. I am curious to know this: Is the Navy conduct- ing any research on thermochemical water, Commander. What pro- grams are being carried out? Commander PETZRICK. I am not aware of any on thermochemical water. H. & D. Dr. WATERMAN. Perhaps the closest program would be the efforts that we have with our submarines. Perhaps the. closest related pro- gram would be in our efforts with nuclear submarines to produce oxygen by high pressure electrolysis of seawater.We get byproducts. Getting rid of hydrogen from those is a critical matter. Perhaps Mi. Carhart could speak further on that. Mr. CARHART. The present. generation, well, the generators are de- vices in which the oxygen and hydrogen are produced at high pressure of between 2.000 and 3.000 pounds. The reason for this is so that you avoid the necessity for having high compressors to put oxygen back into the high pressure vessels. Also, the hydrogen can be pumped overboard without use of a mechanical pump which is noisy. There has been a fair amount of work that the Navy did on analytic devices for this purpose. Mr. McCoR~r~~cTc This reaction goes even with high pressures, Mr. Carhart? Mr. CARTIART. \es. Mr. McCoR~r~~cTc. I take it. from this~ that the Navy is not doing any research into the chemical disassociation of water. Looking at the Navy from a great distance. it would seem t.o me that. in the nuclear ships it would be perfectly satisfactory for producing hydrogen for fuel on a continuing basis if von wanted to use, for instance, on a miclear carrier or for hydrogen-powered airplanes. Commander PETZRTCK. This subject was addressed in these reports, the concept of a mother ship using nuclear power to generate hydro- gen which would be used as a fuel for other ships and aircraft. Mr. McCoR~r~~cK. Yes. Commander PETzRICIc. From a military point of view, you might have too many eggs in one. basket. If somebody gets your mother ship, you have then lost your fuel farm. This causes or poses significant problems. although it is the basis for our studies. That is, the fact that we are. floating in an ocean of resources. If we use that means or any means of converting these resources t.o a useful fuel, this would be attractive. Mr. MOC0RMACK. I wOuld1 not think that you would need the hyclro- gen for anything but aircraft or on very small ships. Your carriers, frigates an~l cruisers would be nuclear powered in the future, wouldn't they? For mobility of submarines, they would use nuclear power. Hy- drogen would be for the small ships and the airc.raft. C~numander PETzRICIi. Yes, Mr. Chairman, in accordance with Title 8, the ca.pita.l ships andl the submarines will be nuclear. It looks like PAGENO="0065" one of the synthetic fuels, such as hydrogen, would be satisfactory for small special mission ships. The difficulty, I think, will surround those ships, well, those in the destroyer size. Mr. MOCORMACK. Have you determined which fuel other than gaso- line, would give you the maximum usable energy per unit volume? What would it be in a plane, for instance-hydrogen or methylamines or methanol or what? Commander PETzRTCK. The jet fuel that we use, the JP-5, has about the maximum energy density considering cost. It is also very desirable because of the safety features. What we are interested in is the middle range of nonaromatic hydrocarbon jet fuels for the aircraft applica- tions. Mr. MCCORMAOK. Suppose that is not available and you went to syn- thetic fuel. Commander PETZRICK. If we went to the synthetic fuels, because of the advantages that are offered by energy density and safety factors, we probably would synthesize a synthetic fuel comparable to the pres- ent JP-5. This means that you would have to work a little harder, adding more hydrogen, say, if you started with a fuel such as coal, or removing more of the carbon, if you went in that direction. That way, you could synthesize the high density fuel rather than stopping with the methane or methanol level. Methanol would only give half of the range that you would get by going to a middle distillate fuel, sir. Mr. MCCORMACK. I see two options-preparing fuel for the gasifica- tion or for the liquefaction of synthetic fuels from coal, which would be hydrocarbons. Suppose you eliminated the hydrocarbons? Suppose that you went to the lower molecular weight fuels, lower density fuels, such as hydrazines and ammonia and methane. Have you any feeling at this time as to which is the best route to go? Commander PETZRICK. We think that the methylamines would give us the performance that is comparable to liquid hydrocarbon fuels on ships and planes. That is, sir, with some penalty in range to the air- craft and with a significant penalty in cost in the case of ships. As is covered in these reports, the most attractive possibility appears to be methyla.mines. Mr. MCCORMACK. This could be fabricated on shore rather than on ships? Commander PETZRICK. We could manufacture these from nitrogen and hydrogen available at sea between the seawater and the air with our nuclear source. Mr. MCCORMACK. You would need a source of carbon. Commander PETZRICK. Yes. If we went to this, this would mean bringing out coal or some other source. There is a significant logistic disadvantage in going to that. Mr. MOCORMACK. The 10 percent penalty with respect to hydrogen, that is not prohibitive with respect to aircraft. You said there would be a 10 percent degradation. I presume that is in the overall perform- ance of range. Commander PETZRICK. Yes. Dr. WATERMAN. Mr. Chairman, there are several other factors that are other than just pure range loss. There is the problem of handling on a combatant ship and refueling it, that is, refueling aircraft. ~nd 62-332 0 - 76 - 5 PAGENO="0066" 60 doing this properly in combat. There is the problem of fires and ex- plosions on the ships. Those have been very difficult, to handle. with conventional fuels. That is why we. went to JP-5. because of the added safety. The range alone cannot be the singular or single element that we consider. Mr. McCoR~iAcIc Is the Navy working on any projects involving ocean thermal gradient production or conversion of energy? Dr. WTATERMAX. Commander Petzrick. Commander PETzRICK. The Navy is assisting ERDA. providing some expertise from our ocean engineering community. Some of our managers are assisting ERDA in analyzing the proposals. We are assisting them with concrete technology for those concepts being pro- posed. We are not sponsoring dv sI)ecific ocean thermal gradient program of our own. We agreed with ERDA that we would give them our expertise to support their programs, using their money. We will cooperate in a joint program rather than initiate anything on our own. Dr. Avery. at one of our laboratory locations, has some thoughts on ocean thermal gradient power plants that are of interest relative to the concepts that we have been discussing, Mr. Chairman. `He would produce ammonia as the product at the po\verplant rather than electricity to be piped ashore. Mr. McCoi~rAcIc A gentleman at Johns Hopkins University was working on that. Commander PETznIOK. Yes. Mr. McCoR3r.~cIc Do von feel that the research or the assessment of this technology being compiled is applicable to onshore use by the utilities? Have, you, studied the problem of hydrogen embrittlement and hydrogen cracking and the reaction with lubricants and reactions with the purnps? Commander PETzRIcic. We have additional information from sub- marine programs in this area. A good deal of information is contained in these reports. I do not feel that this particular field is exhausted. Significant additional work is required in this area. That is, if we went into the actual use or designing systems utilizing hydrogen. Dr. WATERMAN. At this time the studies on hydrogen and the em- brittlement and the problems that~ you mentioned, they are largely in the public domain. They are available to these people. We would be delighted to piovicle whatever assistance we. can. Mr. McCoR~L~cK. This might be a situation where we are. carrying on parallel programs, that is. doing the same research over and over again. Clearly. the fact that the Department of Defense carries on research has many advantages. There is also the possibility, however, that. there is unnecessar duplication. and not the kind of information transfer that. we. would sometimes wish to have. As we get into this particular arena. it seems extremely valriable to have the ERDA personnel working closely with the Navy Energy Research and Development Office to be sure that. no time is wasted. that the ER.DA research arid that which is sponsored by NSF. that this does not necessarily overlap that which has been done by the \ avy. Mr. C~unL~RT. That is right. PAGENO="0067" 61 Dr. WATERMAN. We agree with you. Over the years, I think we have maintained good contact. One of the most important points is that we deal with the major suppliers of materials. We deal directly with them. They, in turn, deal with the other agencies. We have shared our re- search with those people or developers of materials. That provides a pretty direct coupling to us. Commander PETZRICK. Our recent observation of programs initiated by NASA and ERDA suggests the strategy that we should go on to a holding pattern regarding our own work in hydrogen. The studies that we just reported on, they will probably be summarized so that we can have the benefit of the information that is developed in our continuing dialog with ERDA. Our program will then go on to a plateau. We will look to ER.DA and the other agencies that work in this particular area to carry on the work rather than to initiate extensive work in the Navy. Mr. McC0RMAcIC That is good. I hope that we can maintain close liaison. I think that this is really important. Now-, gentlemen, I wonder if, in light of the time problem this morning, that you would be willing to answer any subsequent ques- tions that the committee members may put to you in writing. Mr. CARHART. Yes. Commander PETZRIGK. Yes. Mr. MCCORMACK. I thank you very much for coming this morning. Our next witness is Dr. Derek P. Gregory, director, Energy Systems Research, Instituted of Gas Teclmology. The clock is pushing us. Do you mind if both you and Mr. Sidney H. Law give your testimony. Then we could ask questions. STATEMENT 0]? DR. DEREK P. GREGORY, DIRECTOR, ENERGY SYSTEMS RESEARCH, INSTITUTE 0]? GAS TECHNOLOGY Dr. GREGORY. Yes, Mr. Chairman, that is fine. Mr. McCoRi~rAcw. Your statement, Dr. Gregory, may be inserted in the record without objection. [The complete prepared statement of Dr. Derek P. Gregory is as follows:] PAGENO="0068" 62 INSTITUTE OF GAS TECHNOLOGY THE ROLE OF HYDROGEN IN THE ENERGY FUTURE OF THE UNITED STATES by Derek P. Gregory Testimony Submitted to the HOUSE COMMITTEE ON SCIENCE AND TECHNOLOGY HEARINGS SUBCOMMITTEE ON ENERGY RESEARCH, DEVELOPMENT AND DEMONSTRATION June 12, 1975 Washington, D.C. -E ~ ____________________ 3424 SOUTH STATE STREET I o-r ~ ~ EDUCATtON . RESEARCH AFFILIATED WITH ILLINOIS INSTITUTE OF TECHNOLOGY PAGENO="0069" 63 THE ROLE OF HYDROGEN IN THE ENERGY FUTURE OF THE UNITED STATES Derek P. Gregory Institute of Gas Technology Chicago, Illinois 60616 1. The Role of a Gaseous Fuel in the Future It is commonly believed that to sustain a healthy economic growth, the use of energy in the United States must also continue to grow When we look at the alarming decline in the availability of oil and gas, we can clearly see that a major shift must be made toward other energy sources - nuclear, solar, and coal being the most abundant and important - if the United States is going to have the energy to continue this growth. The use of convention!4 technology stresses the conversion of these energy forms into electricity for delivery to the customer. Because electricity is not readily storable, is expensive to transmit, and is not immediately useful in the vast majority of industrial and domestic energy-consuming equipment, the alternative course of converting these abundant energy sources to a chemical fuel that is more compatible with today' s energy distribution and utilization equipment has merit. In some applications, electricity will serve our needs best; in others, clean fluid fuels will be superior. Although synthetic substitutes for conventional fluid fuels - natural gas and oil - produced from coal are likely to play an important role for an extended period, hydrogen is the chemical fuel with the greatest long-range prospects because it can be pro- duced from nonfossll energy sources. Th~is, hydrogen combines the de- sirable characteristics of conventional gaseous and liquid fuels with the essentially unlimited supply feature stressed by advocates of the all-electric economy. The mixed hydrogen- electricity energy-delivery system may, therefore, well become the best long-term compromise. In the past, the natural gas industry has provided an efficient, reliable, environmentally acc eptable,and inexpensive energy transmis sion-distribution system to supply as much as 30% of our national energy needs to a wide spectrum of industrial, commercial, and residential customers. Much of the investment of the natural gas industry is in this underground delivery system, most of which has a life expectancy greater than that of the re- serves of the fuel that it carries. Be delivering hydrogen as a fuel, the gas PAGENO="0070" 64 industry, which is already in the business of delivering gaseous fuels to its customers, can thus play as important a role in the future in meeting American's energy-delivery needs as it has in the past. 2. The Characteristics of Hydrogen-Energy Studies carried out at IGT and elsewhere have already indicated the following characteristics of hydrogen as an energy source: a. Hydrogen may be produced from water, using energy from nuclear, solar, or other sources by three distinct routes: electrolysis, using electric power; thermochemical decom- position, in which heat is used to drive a number of chemical steps in a cyclic sequence, all the components of the cycle except water, hydrogen, and oxygen being recycled; and by direct irradiation of water-bearing molecules by ultraviolet or nuclear radiation. The technology for each of these three routes is increasingly more complex in the order shown, but electrolysis technology is available today and provides a sound baseline case for economic studies. b. Over long distances, hydrogen is cheaper and less unsightly to transmit than electricity. Underground hydrogen pipelines will be 3 to 5 times less expensive than overhead electric lines and 50 to 100 times less expensive than buried electric trans- mission cables. Moreover, although it has not yet been tested in practice, much of the existing 900, 000 miles of gas trans- mission and distribution systems will probably be usable for hydrogen transmission. Since our future primary energy conversion plants, such as nuclear or solar plants, will be farther from major population centers than they are at pre- sent, long-distance energy transmission will become increas- ingly important. c. Hydrogen can be stored economically in large quantities in facilities somewhat similar to those used for storage of natural gas, whereas it is quite costly and difficult to store substantial amounts of electrical energy. Storage is a vitally important key in the utilization of intermittent energy supplies such as tidal, solar, and wind power, and would be of great economic benefit in keeping high-capital-cost generating plants, such as nuclear plants, operating at high load factors. 2 PAGENO="0071" 65 d. Hydrogen can probably be used in most domestic and industrial natural-gas-burning equipment with only relatively minor modi- fications. Many industrial processes rely on the combustion of a fuel and the use of the resulting combustion gases for specific purposes that cannot be fulfilled by electricity. The complete replacement of all industrial and residential heating equipment with electrical equipment - some of which would have to be specially developed - will present a financial burden that must be shouldered by the user, not by the energy-supply company. Such capital costs are not included in usual estimates for de- veloping an all-nuclear-electric system. e. Hydrogen is an essential raw material for the production of many widely used chemicals including ammonia (for fertilizers) and methanol (for many petrochemical applications). Although it is currently produced from natural gals or oil, bulk hydrogen pro- duction from coal and, ultimately, nuclear energy, with pipeline delivery to the chemical plants, represents an attractive way of maintaining the present fast growth in the production rate of these important materials in the face of a declining supply of natural gas and oil. f. Hydrogen can be used directly to replace coal or coke for iron and steelmaking, and is an essential component in the upgrading of fossil fuels [gasoline from crude, substitute natural gas (SNG) from coal or oil shale]. This represents the simplest way that the major industries of steelmaking and fossil-fuel-refining can make use of large amounts of nuclear energy in their pro- cesses. g. Burning hydrogen and oxygen together is a very elegant way of producing the huge amounts of process steam required by in- dustry. About 17% of all the end-use energy in the United States is used to produce process steam for industry. h. Hydrogen is an excellent fuel for all types of internal-combustion engines because it allows greater efficiency of operation and very clean exhausts. Its unique property of being extremely light (only one-third of the weight of jet fuel for the same energy con- tent) adds tremendous incentive for its use as an aircraft fuel. In spite of some major technological problems still to be resolved, hydrogen made from nuclear energy represents the technically simplest way of achieving a nuclear-powered automobile or airplane. 3. Is the Hydrogen-Energy Option Open to Us Now? Based on these advantageous features of hydrogen, I believe the U. S. national energy policy should be directed toward the ultimate goal of a mixed hydrogen-electricity energy system because both of these energy forms can be made from a wide variety of abundant, domestic primary energy sources, including coal, oil shale, and geothermal, wind, tide, and solar energy. 3 PAGENO="0072" 66 Thus, once energy consumers have become accustomed to the use of either hydrogen or electricity, they will never have to be asked to make a change again because the energy industry would be able to adjust from one raw energy source to another without interfering with the consumer' s equipment. This is in direct contrast to the presen~ prospects, for example, of modifying automobiles to accept alternative blends of gasoline, alcohols, and diesel fuel or modifying industrial combustion equipment to allow the substitution of coal for natural gas and oil. Although the electricity option is clearly open to us because enough ex- perience has been gained with electric energy to enable us to assess its economics, efficiency, and technology quite accurately, the hydrogen-energy option is not available to us at present for a number of reasons, primarily questions of unattractive economics, resulting from relatively low system efficiencies, and questions of safety and compatibility of hydrogen with existing equipment. I believe that these questions should be resolved guic~ē~y so that we can determine whether the potential advantages of hydrogen energy are indeed likely to be realized in a practical and economically attractive way and can thus plan our nation' s energy future accordingly. 4. What Needs to be Done Today Relatively little research in hydrogen energy is going on in the United States today, and most of it is supported by various government departments. Because industry is rightfully mainly concerned with relatively short-term problems of energy supply, longer term programs such as the development of hydrogen energy become the responsibility of government for funding. While I believe that a considerably increased overall research effort in hydrogen energy is required now, I feel that, even with the present overall level of effort, insufficient emphasis is being place on several areas: a. Current hydrogen-energy research is primarily, and rightly, focused on the production area because this is an area where major im- provements in efficiency may be made. However, significant ef- ficiency losses are also apparent at the utilization end of the system, and considerable advances appear possible in designing or modifying combustion equipment to take advantage of the unique properties of hydrogen. The use of hydrogen in conventional natural-gas-fired burners appears to require only minor burner modifications, but, to date, detailed design and testing of modified burners has not been a significant feature of any hydrogen-energy research program. 4 PAGENO="0073" 67 Although no major conversion problems are envisaged, I am surprised that this particular end-use aspect of hydrogen energy has received so little attention, in contrast to the use of hy- drogen in automobiles and aircraft. Fifty-two percent of total U. S. energy consumption is used for combined space heating, industrial process heating, and industrial process steam appli- cations. About hail of this amount is now being supplied by natural gas. The natural-gas-fueled equipment used in these applications could seemingly be converted to hydrogen far more easily and far more cheaply than to electricity. Not many people realize that the amount of energy used in the United States to produce industrial process steam alone is 17% of the total national energy consumption, about the same as that used to drive all of the automobiles in the country. It seems to me that the conversion of this sector of the energy market to non.fossjl fuels, through the use of hydrogen, should receive as much emphasis as the efforts now being made to develop hydrogen-fueled or battery-operated automobiles. b. Considerable effort is being expended on the use of hydrogen as an energy-storage medium. Current work emphasizes the role of hydrogen in an "electricity in-electricity out" system, in which efficiency losses of the second electricity generation step are significant and reduce the attractiveness of the concept. I believe that more emphasis should be given to concepts that include the use of stored hydrogen as a direct supplementary fuel. c. Much of the natural gas industrys' transmission and distribution equipment, including regulators, valves, meters, and pipework, will, I believe, be compatible with hydrogen, but little or no testing and demonstration work is being undertaken at present to prove this point. I feel that the accumulation of several years of experience in this area, by a demonstration project in- volving equipment away from public premises, would domuch to dispel the doubts of those who have quite justifiable fears about the safety aspects of putting hydrogen into the hands of the public. 5. How Should Hydrogen Energy Research be Directed? After having conducted 3 or 4 years of preliminary research into the hydrogen-energy concept, we can make a strong case for its serious con- sideration as a long-term contributor to the U. S. energy system - at least a strong enough case to justify as significant a research and demonstration effort as is now being applied to other concepts such as superconducting transmissio.ri, battery storage, and some advanced solar-energy systems. I also believe that the outstanding problems have been well-enough defined to allow a properly balanced research program to be formulated. What is 5 PAGENO="0074" 68 not clear, at present, is where such a program should be located within the Federal Governments research organizations. In December 1974 at least seven different Government agencies, including AEC, NASA, EPA, NSF, DOD, DOT, and the Department of Commerce, were conducting hydrogen-energy programs in at least six National Labora- tories and at least five NASA field centers. Although this work is very valuable and well managed, it has not been adequately coordinated; the es- tablishment of ERDA has not changed this situation materially. This may be because hydrogen does not have a logical and obvious "home" within the ERDA functional assignments. It certainly does not fit into fossil or nuclear energy, environment and safety, national security, or conservation. The most appro- priate division is that of "Solar, Geothermal, and Advanced Energy Concepts," but because hydrogen is not an energy source, it does not fall into place alongside the other interests of this division. Since "Electric Power Trans- mission" and "Energy Storage" are assigned to the Division of Conservation, hydrogen may fit better here. We must be careful that, because of this division of responsibility, hydrogen energy is not neglected in Government energy research activities. At present, there seems to be a distinct danger that several Government- sponsored "overview" activities in hydrogen are all likely to revert to the review and planning stage, so that much of the momentum and. expertise gained by research teams is in danger of being lost. 6. Attachments for the Record The following publications are appended to this testimony to provide background for the statements I have made: * "The Hydrogen Economy," reprinted from Scientific American, provides a general background on the overall concept of hydrogen energy and its advantages. * "Wiat We Can Do Now as Utility Industry Management and Govern- ment Planners " is a paper given to an IGT Members' Symposium on "Pipeline Hydrogen - Fuel for the Nuclear Age." This outlines some recommendations for both Government and utility research planning in the field of hydrogen. 6 PAGENO="0075" 69 * Worldwide Research Activities in Hydrogen Energy" discusses the objectives and timing of hydrogen research activities known to be in progress or completed in December 1974. It discusses the step- wise introduction of h~rdrogen. into the fields of chemical feedstocks, fuel (oil and coal) refining, steelmaking, energy storage, supple- menting natural gas, and transportation and the ultimate use of hydrogen as a natural gas replacement. The document als' contains a comprehensive listing of worldwide hydrogen projects completed or now in progress. * "Hydrogen Energy Technology Today and Tomorrow" summarizes significant hydrogen research that is in progress, its applications, and its shortcomings, and discusses in particular the reasons why overall systems efficiencies, which are at present lower for hy- drogen than for electricity, cai. be expected to increase to values comparable to those of electric systems. PAGENO="0076" 70 SCIENTIFIC Established 1845 j%J~~I Eli! CAN January 1973 Volume 228 Number 1 The Hydrogen Economy A case is made for an energy regime in which all energy sources would be used to produce hydrogen, which could then be distributed as a nonpolluting multipurpose fuel by Derek P. Gregory The basic dilemma represented by what has been termed the "world energy crisis" can be simply stat- ed: At the very time that the world economy in general and the economies of the industrialized countries in partic- ular are becoming increasingly depen- dent on the consumption of energy, there is a growing realization that the main sources of this energy-the earth's nonrenewable fossil-fuel reserves-will inevitably be exhausted, and that in any event the natural environment of the earth cannot readily assimilate the by- products of fossil-fuel consumption at much higher rates than it does at present without suffering unacceptable levels of pollution. What is not generally recognized is that the eventual solution of the energy problem depends not only on develop- ing altemative sources of energy but also on devising new methods of energy' conversion. There is, after all, plenty of "raw" energy around, but either it is not in a form convenient for immediate use or it is not in a location close enough to where it is needed. Most of the research- and-development effort in progress in the U.S. on the energy problem is de- voted to finding ways to convert chemi- cal energy (derived from fossil fuels), nuclear energy (derived from fission or fusion reactions) and solar energy (de- rived directly from the sun) into elec- trical energy. At present nuclear'fission plants sup- ply about 1.6 percent of the electricity consumed in the U.S. (Of the remainder, fossil-fuel plants supply about 82 per- cent and hydroelectric plants about 16 percent.) Assuming that the develop- ment of economically feasible "breeder" reactors will soon eliminate any short- term concem about the resource limita- tion of nuclear energy, then by the year 2000 nuclear plants may be supplying as much as half of the nation's elec- tricity. If this projection is correct, and if the "energy' gap" of the future is to be filled with nuclear power made available to the consumer in the form of electricity, then the U.S. will have gone a long way toward becoming an "all-electric econ- omy." This trend can be detected al- ready: the demand for electricity is cur- rently growing in the U.S. at a much higher rate than the overall energy de- mand [see illustration on next page]. It has been estimated that whereas the overall U.S. energy' consumption will double by the year 2000, the demand for electricity will increase about eight- fold, raising the electrical share of total energy- consumption from about 10 per- cent to more than 40 percent. The question naturally arises: How desirable is this trend toward a pre- dominantly' electrical economy? Specifi- cally, are there any other forms of en- ergy that can be delivered to the point of use more cheaply and less obtrusive- ly than electrical energy can? Consider such major energy--consumption cate- gories as transportation, spece heating and heavy industrial processes, all of which are primarily supplied today with fossil-fuel energy, mainly for reasons of economy and portability. As the fossil fuels run out, they will become more ex- pensive, making the direct use of nu- clear electrical energy relatively more economical. In this situation a case can be made for utilizing the nuclear-energy sources indirectly to produce a synthetic secondary fuel that would be delivered more cheaply and would be easier to use than electricity in many large-scale ap- plications. In this article I shall discuss the merits of what I consider to be the leading candidate for such a secondary fuel: hydrogen gas. many respects hydrogen is the ideal fuel. Although it is not a "natural" fuel, it can be readily synthesized from coal, oil or natural gas. More important, it can be produced simply by splitting molecules of water with an input of elec- trical energy derived from an energy source such as a nuclear reactor. Per- haps the greatest advantage of hydrogen fuel, however, at least from an environ- mental standpoint, is the fact that when hydrogen bums, its only combustion product is water! None of the traditional fossil-fuel pollutants-carbon monoxide (CO) carbon dioxide (CO2) sulfur di- oxide (SO2), hydrocarbons. particulates, photochemical oxidants and so on-can be produced in a hydrogen flame, and the small amount of nitrogen oxide (NO) that is formed from the air entering the PAGENO="0077" 71 flame can be controlled. Moreover, as- suming that the energy options are re- stricted to the use of effectively `un- limited" materials such as air and water, hydrogen is by far the most readily syn- thesized fuel. In principle, then, one can envision an energy economy in which hydrogen is manufactured from water and electrical energy, is stored until it is needed, is transmitted to its point of use and there is burned as a fuel to produce electricity, heat or mechanical energy [see illustra- tion on opposite page]. Such a hypothet- ical model is not without its problems and disadvantages, but on balance the benefits appear to be so great that I be- lieve at the same time that we are mov- ing toward an "electric economy" we should also be moving toward a "hydro- gen economy," Just as the food and beverage industry has found it uneconomical to collect and reuse empty containers, so the present energy industry cannot afford to collect and recycle used "energy containers": the by-products of the combustion necessary to produce the energy. The drawback in both cases is that the "no deposit, so return" system throws the burden of recovery and recycling onto the environment. Apart from the obvious harmful effect on the earth's atmosphere, this kind of energy cycle suffers from the further disadvantage of having an ex- tremely slow step of several million years' duration for the re-formation of fossil fuels from atmospheric carbon dioxide [see illustration on page 16]. That is the basic reason we are running out of fossil-fuel reserves. In the hydro- gen cycle, in contrast, only water is de- posited into the atmosphere, where it rapidly equilibrates with the abundant and mobile water supply on the earth's crust. At another location the water is re- converted to hydrogen. The system is characterized by negligible delay and does not disturb the environment, yet it relies on the environment to carry out the "return empty" function, Assuming the availability of an abundant supply of nuclear or solar energy, this system can be operated as rapidly as the demand requires without depleting any natural resources. The idea of using hydrogen as a xvii- thetic fuel is far from new. In 1933 Ru- dolf A. Erren, a German inventor xvork- ing in England, suggested the large.scale manufacture of hydrogen from off-peak electricity. He had done extensive work on modifying internal-combustion gines to run on hydrogen, and the main object of his suggcstioss was to eliminate automobile-exhaust pollution and to re- lieve pressure on the importation of oil into Britain. (It is interesting to note that 40 years later the U.S. is concerned with the same two problems: automobile pol- lution and an increasing dependence on oil imports.) Others have suggested using hydro- gen as a fuel or as a means of storing eu- ergy. F. T. Bacon, a pioneer in the de- velopment of fuel cells in England since the 1930's, has always had as his ulti- mate objective the development of a hydrogen-energy storage system using reversible electrolyzer fuel cells. More recently the U.S. Atomic Energy Com- mission sponsored a series of studies during the 1960's of "nuplexes"-nucle- ar-agricultural-industrial complexes that derive all their energy from a single nu- clear reactor. The AEC studies included the concept of water electrolysis to pro. vide hydrogen as a precursor to the manufacture of fertilizers and chemicals. Within the past two years several articles have appeared in engineering and sci- entific journals proposing active studies of the production, transmission, storage and utilization of hydrogen in both com- bustion appliances and engines. Such studies are in progress at several uni- versities and industrial research labora- tories in the U.S. and abroad, including my own institution, the Institute of Gas Technology in Chicago, where our work is sponsored by the American Gas Asso- ciation. The difficulty of transporting hydro- gen has historically prevented its use as a fuel. Clearly some better method than compressing it in steel cylinders has to be found. Storage and transportation as liquid hydrogen are already in use; metal hydrides and synthetic organic or in- organic hydrides have also been con- sidered and have promise. There is no reason, however, why hydrogen should not be distributed in the same way that natural gas is distributed today: by un- derground pipelines that reach most in- dustries and more than 80 percent of the homes in this countsy. Before weighing the merits of the hy- drogen-economy concept, it is in. structive to consider the alternative: the all-electric economy. Suppose for a mo- 1018 1017 1018 -~ ~- ----~ ,777 U) I- z w I I Co F- >, (I w 1 w ,` V V 10,, 7 1940 1950 1960 1970 1980 1990 2000 ACCELERATING TREND toward an "all electric" economy is evident in this graph, which 8hOWs that the demand for electricity (bottom line( is growing in the U,S. at a much high' cr rate than the overall energy demand (top line), Assuming that the trend continues, the U.S. is heading for a predominantly electrical economy sometime in the 21st century. The data are from the U.S. Department of CoTmer3e and the Edison Electric Institute. PAGENO="0078" 72 HYDROGEN ENERGY ECONOMY would operate with hydrogen in the form of hydrogen gas undeegroond or in the form of liquid nsa synthetic secondary fuel produced from water in large nuclear hydrogen ab oveground. The hydrogen would then be distributed or solar power stations (left). The hydrogen would be fed into a as it is needed to energy consumers for use either as a direct heat- nationwide network of underground transmission lines (center), ing fuel, as a raw material for various chemical processes or as which would incorporate facilities for storing the energy, either a source of energy for the local generation of electricity (right). mcnt that one does not consider syn- thesizing a secondary chemical fuel; then one must face the prospect of gen- erating and transmitting very large quantities of electricity. To meet the ris- ing demand for electricity in the U.S. new generating stations are already be- ing cor,structed in sizes larger than ever before. A few years ago a 500-megawatt power station was considered a giant. Today 1,000-megawatt stations are typi- cal, and the electrical industry is con- ternplating 10,000-megawatt installa- tions for the future. In spite of the intensive efforts of their designers, the efficiency of steam-driven electric-power stations is still fairly low: about 40 percent for a modem fossil-fuel plant and 33 percent for a nuclear platst [see `The Conversion of Energy," by Claude M. Summers; SctENTtFIC Axteot- CAN, September, 1971). As a result the waste heat released from these large plants, or clusters of plants, is consider- able. Accordingly they must be located near large bodies of water where ample cooling is available or in open cuuntry where cooling to the atmosphere will have no adverse local effects. Concem over the safety of nuclear reactors is also having a strong influence on the location of such plants. Because of these con- straints the huge power stations of the future are likely to be built at distances of 50 miles or more from the load cen- ters. Power stations located on offshore platforms floating in the ocean are al- ready pla;stsed for the U.S. East Coast. Posver must be moved from the gener- ating stations to the load centers. High- voltage overhead cables are expensive, in terms of both equipment costs and the land they occupy, and they are vulner- able to storm damage. Moreover, the electrical industry is encountering con- siderable resistance to the continued stringing of overhead power-transmis- sion lines in many areas. Underground cables for carrying bulk power cost at least sine times (and sometimes up to 20 times) as much as overhead lines and thus are far too expensive to be used over long distances. Underground trans- tnission is used only where the expense is justified by- other considerations, such as aesthetic appearance or very expensive right.of-svav. Much work is being done to develop cryogenic superconducting cables, sshich svould allosv large cur- rents to be carried underground at a reasonable cost. At present. hosvever, tlse technolog~ is still at an early stage of de- velopment. Some form of electrical storage svould be of great value to the electrical indus- try, bcrause power stations work most efficiently sshen operated at constant output at their full rated load. Since con- sumer demand varies widely both sea- sotially and during the day, however, the generating rate must be adjusted con- titsuously. The only practical way avail- able today to store large quantities of electrical energy is the pumped-storage plant, a reversible hydroelectric station; unfortunately only a limited number of sites are geographically suitable for such systems. rfhus it appears that several of the problems faced by the electrical in- dustry-the siting of posver stations, the expense of underground transmission and the lack of storage-arc being ampli. fled by~ factors that lead to larger and more remote posvec stations. The hydro- gen-economy concept could help to al- leviate these problems. Hydrogen can be transmitted and dis- tributed by pipeline in much the same way that tsatural gas is handled today. The movement of fuel by pipeline is one of the cheapest methods of energy trans- mission; hydrogen pipelining would be tio exception. A gas-delivery system is usually located underground and is therefore inconspicuous. It also occupies less land area than an electric-posver litse. Hydrogets can also be stored in huge quatstities by the very same tech- niques used for natural gas today. Let us take a look at the existing gas- transmissiols netsvork in the U.S. In 1970 a total mileage of 252,000 miles of trunk pipelitse was in operation, carrying a total of 22.4 trillion cubic feet of gas dur- ing the y.ear [see illustration on pages 18 and 19). Such a pipeline system is ~~~GR0UND HYDROGEN STORAGE DOMESTIC FUEL PAGENO="0079" 73 needed because natural-gas sources are located in certain parts of the country, whereas markets for the gas exist in other areas. In the hydrogen economy hydrogen gas would be produced from large nu- clear-energy (or solar.ene;gy) plants lo- cated in places that provide optimum cooling and other environmental facili- ties. Even coal-fueled hydrogen genera- tors, located close to the mine mouths, could be integrated into this power-gen- eration network. A pipeline transmission system would grow up to link these loca- tions to the cities in a way analogous to the growth of the natural-gas transmis- sion system. The technology for the construction and operation of natural-gas pipelines has been well developed and proved. A typical trunk pipeline, 600 to 1,000 miles long, consists of a welded steel pipe up to 48 inches in diameter that is buried underground with appropriate protec- tion against mechanical failure and/or electrochemical corrosion. Gas is pumped along the line by gas-driven compressors spaced along the line typically at 100- mile intervals, using some of the gas in the line as their fuel. Typical line pres- sures are 600 to 800 pounds per square inch, but some systems operate at more than 1,000 pounds per square inch. A typical 36-inch pipeline has a capacity of 37,500 billion British thermal units (Il.t.u.) per hour, or in electrical equiva- lent units 11,000 megawatts, roughly 10 times as much as a single-circuit 500- kilovolt overhead transmission line. Natural gas is not the only gas to be moved in bulk pipelines, although no other gas is moved on such a scale. Car- bon dioxide, carbon monoxide, hydrogen and oxygen are all delivered in bulk by pipeline. So far industry has had no incentive to pipeline hydrogen in huge quantities over great distances, but where it now pipelines hydrogen over short distances it uses conventional nat- ural-gas pipeline materials and pres- sures. There is no technical reason why hydrogen cannot be pipelined over any distance required. Because of the lower heating value of hydrogen (325 B.t.u. per cubic foot com- pared with about 1,000 B.t.u. per cubic foot for natural gas) three times the vol- ume of hydrogen must be moved in order to deliver the same energy. Hydrogen's density and viscosity are so much lower, however, that the same pipe can handle three times the flow rate of hydrogen, al- though a somewhat larger compressor energy is required. Thus where existing pipelines happen to he suitably located, they could be converted to hydrogen with the same energy.carrying capacity. In the hydrogen economy it will bc possible to stoic vast quantities of hydro- gen to even out the daily and seasonal variations in load. Natural gas is stored today in two ways: in underground gas fields and as a cryogenic liquid. At 337 locations in the U.S. natural gas is stored in underground porous-rock formations with a total capacity of 5,681 billion cu- bic feet. Whether hydrogen can be stored in underground porous rock can be finally ascertained only by future field trials. At present, however, 30 billion cubic feet of helium, a low-density gas with leakage characteristics similar to those of hydrogen, is stored quite satis- factorily in an underground reservoir near Amarillo, Tex. Cryogenic storage of natural gas is a rapidly growing technique; at 76 loca- tions in the U.S. "peak shaving" opera. lions involving liquefied natural gas are in use or under construction. There is no technical reason why a similar peak. shaving technique cannot be employed with liquid hydrogen. Liquid hydrogen used to be considered a hazardous labo- ratory curiosity, but it is already being used as a convenient means of storing ENVIRONMENT > WATEJ~ ENVIRONMENTAL EFFECTS of the present fossil-fuel energy cycle and the proposed hydrogen-fuel energy cycle are compared here, When fossil fuels are burned to release their stored energy (top), the environment is relied on to accommodate the combus- tion by.products, The re.formation of the fossil fuels from atmo- spheric carbon dionide take, millions of years (broken line), On the other hand, when Itydrogen is burned as a fuel (bottom), the only combustion prodttst is scater, which is easily assitnilated by the environment. The fuel cycle is completed rapidly without de- pleting limited resources or accumulating harmful waste products. STDRAC,F ANn TRAPISPDRT FOSSIL FUELS A ENERGY *I 11.1 COMBUSTION - `I' OXYGEN ENVIRONMENT WATER, CARBON DIOXIDE, ETC. VEc~ETAT1OU - NUCLEAR FUELS ~1' ELECTROLYTIC HYDROGEN - `I' STORAGE AND TRANSPORT ENERGY ii -~ COMBUSTION - PAGENO="0080" and transporting hydrogen over long dis- tances. Liquid hydrogen is regularly shipped around the U.S. in railroad tank cars and road trailers. The technology for the liquefaction and tankage of hy- drogen has already been developed, mainly for the space industry. Indeed, the largest liquid-hydrogen storage tank is at the John F. Kennedy Space Center; it has a rapacity of 900,000 gallons, equivalent to 37.7 billion B.t.u. or 11 million kilosvatt-hours [sc-c jOust ration at riglstl. Although the energy content of this tank is only about 4 percent of the energy content of a typical liquid-natu- ral-gas peak-shaving plant, its energy capacity is 73 percent of the capacity of the world's largest pumped-storage hy- droelectric plant, located at Ludington, Mich. The cryogenic approach to energy storage has the advantage of being ap- plicable in any location, no matter what the geography or geology, fartom that limit both underground gas storage and pumped hydroelectric storage cc he simplest way to manufacture hy- drogen using nuclear energy is by electrolysis, a process in which a direct electric current is passed through a con- ductive water solution, causing it to de- compose directly into its elementary con- stituents: hydrogen and oxygen. Com- plete separation of the two gases is achieved, since they are evolved sepa- rately at the two electrodes. Salts or alka- lis, which have to be added to the water to increase conductivity, are not con- sumed; thus the only input material re- quired is pure water, A number of large-scale electrolytic hydrogen plants are operated today in locations where hydrogen is needed (for example in the manufacture of ammonia and fertilizers) and where cheap electric poiver (usually hydroelectric power) is available One of the largest commercial electrolyzer plants in the ivorld is oper- ated by Cominco, Ltd., in British Co- lumbia [see illustration on pagc 20). This plant consumes about 90 mega- watts of power and produces about 36 tons of hydrogen per day for syntlsesis into ammonia. The by-product oxygen is used in metallurgical processes Similar large plants are located in Norway and Egypt. Many smaller plaits exist where hydrogen is produced from unattended equipment. The theoretical power required to pro- duce hydrogen from water is 79 kilo- watt-hours per JO® cubic feet of hy- drogen gas. In practice the large in- dustrial plants are only about 60 percent efficient; a typical power-consumption figure is 160 kilowatt-hours per 1,000 cubic feet of hydrogen- This power re- quirement represents a major part of the plant's operating cost. Thus there is a considerable incentive-indeed, a real need-to increase the operating efficien- cy- of such plants if one is to consider using electrolytic hydrogen as a fuel. The fuel cell, the subject of intensive research and development as part of the space program over the past 15 years, is really an electrolyzer cell operating in reverse. The simplest fuel cell to build and operate is one that operates on hy- drogen and oxygen, yielding water and electric power as its products. Hydro- gen-oxygen fuel cells svere selected and developed for both the Gemini and the Apollo programs because of their high efficiency, which reduces the amount of fuel needed aboard the spacecraft to supply its electric power. Much effort has gone into developing fuel cells with high efficiencies. This same technology can be applied to increase the efficiency of the reverse process: electrolysis. Elec- trolytic cells are operating in aerospace laboratories today with an efficiency of more than 85 percent. Increasing the electrolyzer efficiency alone has relatively little merit as long as the present power-station efficiency in converting nuclear heat to electric power is only about 33 percent. This efficiency loss can, however, also be circumvented. For example, Cesare Marchetti at the Euratom laboratories in Italy has de- signed a chemical process for the ther- mal splitting of water to hydrogen and oxygen directly using the heat energy produced by a nuclear reactor. If water is to be split into its elements directly, it must be heated to very high tempera- tures-about 2,500 degrees Celsius-to achieve dissociation. Not only are such temperatures not available from nuclear reactors but also the gases cannot con- veniently be separated from each other before they recombine. It is possible to conceive of a too-stage reaction in which a metal, say, reacts with steam at 74 QUID H'(OROG~~~ NO SMOKING ENERGY STORAGE in the form of liquefied hydrogen is already a routine practice in the space industry. This vacuum-insulated cryogenic tank at the John F. Kennedy Space Center, for example, contains 900,000 gallons of liquid hydrogen for fueling the Apollo rockets. It ic the largest facility of its kind in exi'tenee. In terms of energy its contents are equivalent to 37.7 billion B.t.u. of heat or 11 million kilowatt-hours of electricity. PAGENO="0081" 75 a reasonable temperature to produce hy- drogen and a metal oxide. The hydrogen is easily separated from the metal oxide, which in turn could be decomposed to oxygen and the metal by the application of heat. Unfortunately there does not ap- pear to be any suitable metal that under- goes such a series of reactions at tem- peratures losv enough to be compatible with nuclear reactors, svhose construc- tion materials limit operating tempera- tures to about 1,000 degrees C. Marchetti's concept, therefore, is a far more complex reaction sequence involv- ing calcium bromide (CaBr2), water (H50) and mercury (Hg), in which, ex- cept for the hydrogen and oxygen, all the reactants are recycled. Each of the reactions proceeds a~ temperatures be- low 730 degrees C., which can be achieved in a nuclear reactor. Although the process appears to be feasible, de- velopment work is still required to try to bring the overall efficiency up and the cost down to practical limits. The quantities of hydrogen that the hydrogen economy would require are immense. For example, if sve were to produce today an amount of hydrogen equivalent to the total production of natural gas in the U.S., sve would have to provide during one year the same fuel value as 22.5 trillion cubic feet of gas, or 22.5 quadrillion (101~) B.t.u. of energy. This corresponds to about 70 trillion cubic feet of hydrogen, svhich, if we could produce it at a steady rate all year round from nuclear electrolytic plants, would require an electrical input of more than a million megawatts. The present total electrical generating capacity in the U.S. is 360,000 megawatts, so that we are envisioning a fourfold increase in generating capacity, which would re- quire the construction of more than 1,000 new 1,000-megasvatt posver sta- tions. That is in addition to the rapidly increasing demand for electric power for other uses. During the past five years, in contrast, the electrical generating ca- pacity in the U.S. has gro\vn by "only' 105,000 megawatts. Such a formidable task of increasing capacity, however, does not follow sole- ly from our turning to a hydrogen econo- my. As our huge consumption of fossil fuels declines in future years, sse must provide at least an equivalent alternative energy source. Such numbers give a taste of the energy revolution that must take place within the next half-century. .A~ present the cheapest bulk hydrogen is made from natural gas. Clearly since hydrogen from such a source can- not be cheaper than the starting materi- al, it cannot therefore be expected to re- place natural gas as a fuel. Electrolytic hydrogen is even more expensive, unless very cheap electric power is available. Today's electricity prices are based on supplying a fluctuating load, but the capability of hydrogen storage would even out the load and might reduce the price of electricity somewhat. Although the cost of hydrogen pro- duced from electricity must always be higher than the cost of the electricity, it is the losver transmission and distribu- tion cost of hydrogen compared with electricity that makes it advantageous to the user. The latest economic figures published by the gas and electrical in- dustries can be used to derive the pro. duction, transmission and distribution shares of average prices, charged to all types of customers, for gas and electric- ity, and these data can be compared in turn with corresponding figures for hydrogen made by electrolysis [see il- lustration on page 21]. The figures for hydrogen are derived from the hypo- thetical assumption that all the electric- ity generated in the U.S. in 1970 was converted to hydrogen, which was sent through the existing natural-gas trans- mission network (for an average distance of 1,000 miles) and was delivered to cus- tomers as a gaseous fuel. The electrolysis charge of 56 cents per million B.t.u. is derived from AEC estimates of the cost of building advanced electrolyzer cells. The hydrogen transmission and distribu- tion costs are based on natural-gas costs, adjusted to take account of the different physical properties and safety factors for handling hydrogen. Tsvo things are obvious from such a comparison. One is that today it is far cheaper for the average customer to buy energy in the form of natural gas than it is in the form of electricity. The other is that it should already be possible to sell hydrogen energy to the gas user at a losver price than he now pays for elec- tricity. Clearly, however, this hydrogen ss'ill find no markets while natural gas is as cheap as it is. Looking to the future, we see that natural-gas prices, together with all fos- sil.fuc-l prices, will increase apidly. These rises are brought about liv their short supply, by the influeow- of lollu. on regulations and by such social prcs- soles as land conservation and emplovc. ivelfare applied to the mining industry. In contrast, the price of nuclear energy, although apparently rising fast nosy, can be expected to stabilize somewhat in the l)reeder-reactor era because there swill then be no severe- supply limit. It is not possible at this time to fore- cast accurately what the cost of hydro- gen energy is likely to be, but one can certainly look forward to considerably increased prices for all forms of energy. Even so, in the long run delivered hy- drogen will be cheaper than delivered natural gas and very probably also claeaper than delivered electricity. 1~Then hydrogen becomes as universal- ly available as natural gas is today, it will easily perform all the functions of natural gas and others besides. Hydro- gen can be used in the home for cooking and heating and in industry for heating; in addition it can serve as a chemical raw material in many industries, in- cluding the fertilizer, foodstuffs, petro- TRUNK PIPELINES extending for 252,000 miles black lines) already exist in the U.S. for transmission of natural gas from area- 62-332 0 - 76 - 6 PAGENO="0082" chemical and metallurgical industries. Hydrogen rim also be used to generate ek-ctricitv iii local passer stations. The combustion properties of hvdro- gen arc considerably different from those of natural gas. Hydrogen burns with a faster, hotter flame, and mixtures of hy- drogen with air are flammable wider limits of mixture. These factors mean that burners of hydrogen must be designed differently from those of natu- ral gas and that modification of every burner svill be necessary on changeover. Such svidespread modification is not without precedent. A similar operation was carried out when the U.S. changed from manufactured gas (about 50 per. cent hydrogen) to natural gas; several 76 European countries have recentl~ un- dertaken the same conversion. Hydrogen, because it burns without noxious exhaust products, can be used in an usvessted appliance xxithout hazard. Hence it is possible to conceive of a home heating furnace operating without a flue, thereby sax.ing the cost of a chim. and adding as much as 30 percent to the efficiency of a gas-fired home heating system. More radical changes are pos- sible, moreover, because without the need for a flue the concept of central heating itself to no longer necessary. Each room can have its heat supplied by unflued peripheral heating devices oper- ating on hydrogen independently of one another. Indeed, the vented water vapor svould provide beneficial humidification. Another radical change is the potential use of catalytic heaters. Since hydrogen is an ideal fuel for catalytic combustion, true `flameless" gas heating is possible, ssitb the catalytic bed bring maintained at one desired temperature, even as lose as 100 degrees C. This prospect promises to revolutionize domestic heating and cooking techniques in the future. With such low temperatures it is virtually im- possible to produce nitrogen oxides, thus eliminating the only possible pollutant from a hydrogen system. Hydrogen is also the ideal fuel for fuel cells. The technological problems that have faced the development of practical, commercially economical fuel cells for tons) of natural gas per day. Similar networks of underground hy' drogen'gas pipelines would enable the giant nuclear for solar) power stations of the future tn be located far from the load centers. sehere the gas is prodt~'eed (gray) to areas where it is consumed. The system, which is constructed almost entirely of sselded steel pipe, carries approximately 61.4 billion cubic feet (or 1.5 million PAGENO="0083" 77 more bait a decade re see touch cc- duced if hydrogen can lie used as furl. Fuel-cell electricity generators operating on lrs'drogen should be at least 70.per- ccitt efficient and caii realistically be ex- pected to find a place in the home, hi commercial and industrial buildings antI in industry. Larger, urban electrical generating stations could Ite fuel-cell systems or could be hydrogen-fueled steam stations. Au earlier concept of operating a closed-cycle steam-turbine system on a hydrogen-oxygen fuel sup- ply could become practical through the use of rocket-engine technology. \Vork- ers at the Massaclsusetts Institute of Technology have proposed such a sys- tem for submarines; it has beets reported that an overall efficiency of 55 percent can be anticipated from it. Hydrogen is an exrelleiit fuel for gas- turbiite engiises and has been proposed as a fuel for supersoisic jet trasisports. tIns kind of tsr furl susage and tatikage as ltqstol hydrogen (ii' Pirtical. Although lie ho ge sobiinc requited may make its use less attractive for subsonic aircraft, the sire considerable- sasitg in is-right over an equivalent fur-I load of kerosene- give-s hydrogen a distinct ad- s-antage. Cous'entional intr'rnal-consbus- tutu engines ssill also operate nit hvrlro- grim if they are suitably modified or cc- designed. R. J. Schoeppel of Oklahoma State Uiiivs-rsity and others have sltosvn th;tt if hydrogen is itijected into the cii- gine through a valve in a manner similar to Ite ivay fuel is iisjected into a diesel engine, the preignition characteristics of hydrogen are overcome. Others, iuclud- iiig Marc Nesvkirk of the International Materials Corporatioit and Morris Klein of lie Pollution Free Posver Corporation, have reported satisfactory operation of eoiiventioisal automobile eisgines nit hiy- drogen using carburetor aiid manifold mittitlifti it ums. \lr'ansvliili' Vmilham . D. Esrln-r of Esrlim'r Technology Associates hits proposed a i adically diflr-r-nt .ip- pionhm to automobile engimu- desigmi, iisuiig a sR-am system fueled liy lioth by- antI oxygen. The use of liquid hs'- rlrogeit as a routimie private-autimniobile fuel is qiiestioiiahmle ui the gruiiiid if safe-tv, although it is probably apphicalile to fleet useis, such as bus lines aiid taxi- cali fleets. Richard H, Wissvahl, Jr., and Janies J, Reilly if the llrookhaven National Lab- oratory have proposed the use uf metal- lic hydrides to store hydrogen as a fuel for vehicles. A magnesium-alloy hydride sviil store hydrogen energy as efficiently (nit a sveiglst basis) as a tank sf liquid hydrogen, but some technical problenss must still be overcome, At present there seems to lae no single, ubvious svay in which automobiles can be operated sin hsydrugen fuel, but considerable svisrk is LARGE ELECTROLYZER PLANT for the production of hydro- cover more than two acres, consume about 90 megawatts of power gen by the electrical decomposition of water is operated by Co. and produce about 36 tons of hydrogen per day for synthesis into minco, Ltd., in British Columbia. The 3,200 electrolytic cells, which ammonia. Byproduct oxygen is used in metallurgical processes. PAGENO="0084" 78 going on to investigate tin' v:iiiüiis op- tions available. If one ha.s (ii svntln'siie a suitalili' liquid fuel for automobiles md aircraft, time starting material for tin fuel must 1)0 hydrogen in any case. One of the main criticisms of tin' liv- drogen-ceonomy concept is that hy- drogen is too dangerous for use in this way. Undoubtedly hydrogen is a hazard- ous material and must he handled svith all due precautions. If it is handled prop- erly, hosvever, in equipment designed to ensure its safety, anyone should be able to use it without hazard. In the days of manufactured gas (gas made from coal), which consisted of up to 50 percent hydrogen aim;1 contained about 7 percent carbon monoxide, pro- pie managed to live with the fire and cx- plosion hazards of hydrogen as svell as the toxic hazards of carbon moiimmxmde. Of course, it takes ontv one niajoi di- saster to alert evecyminc to a hazard. TIme most famous hydrogen accident, the Hindenburg airship disaster of 1937, ix still rememliered svitii awe. Indeed, the almost universal fe-ar of hvdcimgen has becii described as the "J!ismcleiihsmeg syn- drome." Spectacular as it svas, hosvcver, that fire seas almost iiver within tsvo minutes, aiid of the 97 persons iii board, 62 survived. Very strict codes are enforced fur time use of natural gas today; es'en stricter ones arc applied to industiv for the use of hydrogen. Most of these emmdes are cc'- alistically based on reducing time ehaimecs of accideimts. Just es we have designed apparatus and procedures to enable us to fill our automobile tanks svith gasoline and carry the resulting 20-gallon "fire bomb" at speeds of up to 70 miles per hour along a crosvded highss'ay aiid park it overnight right inside our homes, we caii surely devise safe practices for han- dling hmydrngeii. Hydrogen cannot be detected by the senses, so that a leak of pure hydrogen is particularly hazardous. Odorants arc routinely used to make natural-gas leaks obviiius, liosvever, and no doubt the same eaii lie duiie svith hydrogen. Hy- drogeim flames are also almost invisible and are therefore dangerous on this score. Heiice an illuminant max' have to be added to the gas to make the flame visible'. The flainmaiiilitv limits of liv- drogen mixed svith air ace very svide, from 4 to 75 perceiit. It is the iosver limit, almost the same as that for methane (5 percent in air), that causes the fire haz- ard svitli a gas leak. On the benefit side, hosvever, since hydrogen is so much lighter than air and diffuses assay at a far greater rate than methane, a hvdro- gets leak could actually be less hazardous than a natural-gas leak. The most sig. imificant hazardous property of hydrogen is the extremely lose energy required tms ignite a flammable mixture: only a tenth of the energy required to ignite a gaso- line-air mixture or a methane-air mixture aiid well within the energy levels of a spark of static electricity (a probable cause of the Hinck'nburg fire, svhich oc- curred just after a thuncierstorni). Thus safety practices svill have to lie based oii the assumptioii that if a hydrogen fire can occur, it xxiii! Huge quantities of hydrogen are handled in industry quite safely and xvithout accident precisely because proper precautions are taken. To recapitulate briefly, our recover- able fossil-fuel supplies xvtll sooner or later become exhausted; we are already feeling the effects of the limited supply by having to pay more for fossil-based energy. Within the next 50 years we iiiust be prepared to pax' considerably more for energy from all sources, par- ticularly for fossil fuels. One svax' of hati- dung nuclear and other energy sources is to use them to convert seater to hvdro' get: in large central plants and then to use hydrogen as a clean, nonpoiluting fuel. Technically this is already feasible; only relatively simple developments have to be made, iiot approaching the magnitude of the technical tasks of de- x'eloping the alternative energY sources- breeder reactors aiid solar c'imgines- themselves. Economics and safety are the tsvo obstacles to developiiig such a hydrogen econoiiiy. A coiiibination of technical developmriit and the expected adjustment in relative energy prices cats justify the economics, and proper prac- tices and design can ensure safety. If aiid when we move into a hydrogen ecottomy, the world will undoubtedly be a far cleaner place to live in than it is today. z 0 -J -i C- cc ad -J -J 0 0 U cc C' 0 cc > -a 0 > ad -J cc ``C -u.~ EN itEL~TI\ E DELI\ERE1) l'RICES oh variou- foents ot energy are tiroken dunn its liar chart into the sharesre presented by production solid color), transmission (inter- tstedi:mte color) and distribution (light color), The comparison reveal- that at pre'.ent it ~s. much cheaper to buy energy in the form of natural gas than in the form of electricity. Moreover, the breakdossn shoses that although the cost of hydrogen produced from elec- tricity must always be higher than the cost of the electricity, the tosser transmission ntsd distribution costs of hydrogen already make it possible to sell hydrogen energy to the gas user at a delivered price tower than chat he noi. pays for electricity. It is expected that natural-gas prices, together is ith all fossil-fuel prices, ciii increase rapidly in the future. PAGENO="0085" 79 L~~JL~ E~X~L~J I~X~ XE~L~ A Panel Discussion at the Thirty-third Annual Meeting of Members and of the Board of Trustees of the Institute of Gas Technology lIT CENTER * CHICAGO, ILLINOIS * NOVEMBER 21, 1914 PAGENO="0086" 80 PIPELINE HYDROGEN THE FUEL FOR THE NUCLEAR AGE A Panel Discussion at the Thirty-third Annual Meeting of Members and of the Board of Trustees of the Institute of Gas Technology Grover M. Hermann Hall UT Center Chicago, Illinois 60616 November 21, 1974 PAGENO="0087" 81 PIPELINE HYDROGEN THE FUEL FOR THE NUCLEAR AGE INTRODUCTION 16 mm sound film and voice over (vo) EARTH - The Watery Planet No other planet in our solar system has adequate gravity and temperature conditions to support oceans that cover so much of its surface. Our "earth" is 70. 8 per cent water. If this seems contradictory, man has been living this contradiction since the beginning of time. His preoccupation with land has limited him to less than 30 per cent of his total world. His relationship to the sea is still that of primitive hunter. In the past, he could afford this luxury of seeking the obvious. Today, our rapidly changing environment demands that he explore the potential alter- natives of the sea as well as the land. Soon man will turn to the ocean for his water supply, cultivate the ocean for much of his food, and eventually harness it as an energy source. It is this energy source potential that we are concerned with today. The principal component of water is hydrogen . . a combustible gas like natural gas. Hydrogen can even be pumped to high pressure like natural gas. And when it is cooled, it can be stored in cryogenic tanks like natural gas. Basically hydrogen can serve all the conventional applications of natural gas, but with some inherent advantages. Very often it is easier to utilize than natural gas. For example, the fuel cell is actually a hydrogen-consuming device. Before natural gas can be fed into a fuel cell, it must be converted to hydrogen in a reformer. Imagine the huge amounts of hydrogen that will have to be used in the production of SNG from coal. Furthermore, there is a growing acceptance in the scientific community that hydrogen may be at least as good a product from nuclear heat as electricity. Or even a better product than electricity. And, as we move into a nuclear- based economy, this can be a very important alternative to more obvious solutions. INTERVIEWER: Dr. Armand Luxo is Director of Research for Gaz de France. Dr. Luxo, Gaz de France has been conducting research into hydrogen for some years. Will you tell us about that please? DR. LUXO: Why is Gaz de France so much interested in the production of hydrogen from water and atom? Well, we import, for the time being. two thirds of our primary energy from foreign sources as hydrocarbons and we have not sufficient resources in coal to produce large quantitites of substitute natural gas and then we have to rely upon another product coming from water and PAGENO="0088" 82 using nuclear energy for producing it. Hydrogen is not only a raw material useful as a petrochemical feedstock but also is an energy carrier able to extend the uses of nuclear energy. This is the main reason for our research. It could supply customers which could not otherwise be supplied by electricity. Then these considerations can let us understand why we are so much interested in hydrogen and justify the important efforts we have to make to reach this important goal and to study this important and difficult project. VO: Hydrogen is becoming an important synonym for the future of the gas industry of the world. The growing deficit in energy supply must ultimately be met by nuclear energy. Until now, the practical use of nuclear energy has been limited to the production of electricity. If this trend is continued we will be faced with two major problems. First, the inherent high efficiency and low cost advantages of transporting and storing oil and gas are forever lost in an all-electric economy. The re- sult could be an overall decline in efficiency of the U. S. energy system. Secondly, if the consumer is to utilize electricity for applications now served by oil and gas, there will have to be very costly technological changes in consumer equipment. Can our economy afford it? Can the public afford it? Can the gas industry afford it? Hydrogen provides a solid alternative. INTERVIEWER: Leslie Clark is the president of the International Gas Union and the chairman of the Northern region of the British Gas Corporation. Mr. Clark, you just appeared on a panel on the discussion of the future of hydrogen at the World Energy Conference in Detroit - Why is hydrogen being discussed now? CLARK: I think that it is very important that we should discuss hydrogen be- cause the gas industry of the world has become one of the major energy supply industries. It's supplying nearly a third of the world's energy in effective, useful, final energy terms. We also know that in some countries, in some parts of the world, that the supplies of natural gas are beginning to run short and it may well be that within 25 years some countries will need some other form of energy to replace the natural gas they're using now. They already have in existence, of course, extensive transmission and distribution systems which are very effective. They do not offend the environ- ment in any way, they're all below ground and it's a very efficient means of moving energy around. 2 PAGENO="0089" 83 So, we think of how we could replace the natural gas. It's possible to make substitute natural gas from coal but hydrogen is another means of doing this because we are thinking of the period when we shall have to depend very much more on nuclear energy and it is possible to produce hydrogen from nuclear power. VO: Hydrogen isn't new as a fuel. For years the utility gas industry manufactured and distributed low-BTU gas which contained a large proportion of hydrogen. Even natural gas is principally hydrogen. Methane, it's chief component contains one atom of carbon and four atoms of hydrogen. More recently, hydrogen-fueled rockets sent men to the Moon. Military planners talk about hydrogen as fuel for tanks and other combat vehicles. Aviation planners talk about flying our commercial jet planes with hydrogen. INTERVIEWER: Paul M. Ordin is manager for projects related to safety involving cryogenic fluids, the Aerospace Safety Research and Data Institute, Lewis Research Center, Cleveland. ORDIN: Thank you. The Lewis Research Center has been concerned with hydrogen since 1950. Our initial efforts with hydrogen were its use as a rocket fuel. We started working at that time on about 100 lb. thrust engines using small quantitite~s of hydrogen. This we continued until we have our successful rocket program today. About 1955, a program was started in our Center in cooperation with the Air Force to design or modify an existing aircraft that would use hydrogen as a fuel. This work, as I said, started in 1955, and by 1956, we were successful and had actually completed the first and second flight of a B57-B aircraft using hydrogen. Now, a B57-B aircraft is a two-engine aircraft. We modified it so that one bf the engines used hydrogen. The system was designed so that the liquid hydrogen - we used liquid as the storage and it was in a wing-tipped tank - and the liquid in the tank was pressurized with helium. The liquid was sent through a ram-air heat exchanger on the aircraft and the gas was then injected into the engine. VO: There are ecological values in the hydrogen alternative as well. It is a clean-burning fuel that can be readily and economically substituted for liquid fossil fuels in the transportation market. When hydrogen burns, its principal combustion product is water. Since it contains no carbon, it cannot form carbon dioxide or carbon monoxide when it burns. And hydrogen is a safe fuel,, though any form of concentrated chemical energy must be fully understood and handled with respect or it becomes a dangerous hazard. 3 PAGENO="0090" 84 Hydrogen has a safety track record like natural gas and gasoline. For years. liquid hydrogen has been safely transported by rail and over-the-road tankers. NASA utilizes hydrogen extensively in the space program. And, the by-word at NASA is safety. INTERVIEWER: Addison Bain is Systems Engineer. Support Operations. Kennedy Space Center. BAIN: The Apollo space vehicle which carried the astronauts to the moon was launched from the pad in the far background near the grey tower. The on- board quantity of liquid hydrogen for the launch vehicle was 340, 000 gallons which was supplied from the storage sphere which you see in the front. The storage sphere has a capacity of 850, 000 gallons. It transferred liquid hydrogen to the space vehicle (launch vehicle) at the rate of 10, 000 gallons a minute. The sphere itself is supplied by over-the-road tankers each of which have a 13. 000 gallon capacity. The tankers provided the liquid hydrogen from a pro- duction facility 700 miles away. During the Apollo launch program. these tankers hauled over 16, 000, 000 gallons of liquid hydrogen and logged well over 2. 000, 000 miles. As we go into the next major program which is the space shuttle program. we're talking about 40 launches a year. These launches will start in 1979 and go to that activity in about the early 80's. During that time, we expect some 600. 000 gallons a week to be delivered to this site. We expect to use the same hardware. probably more tankers. with exactly the same design that you see here. With an increased activity of 20-fold, we really don't expect any change to our operations. We think the safety guidelines, the operating procedures have all been well established. VO: In spite of all this, there is not unanimous agreement in the scientific community about when, how, or if hydrogen fits into the overall energy supply picture. INTERVIEWER: Dr. Edward Teller is a noted atomic scientist. Dr. Telle: it is widely known that you are a strong advocate for the development of nuclear energy. It has also been widely understood that in moving to a nuclear age, we also are moving to an all-electric economy. More recently we have heard advocation of what is known as The Hydrogen Economy to supplement the all- electric economy. Do you have any views on this? DR. TELLER: We are not moving to an all-electric economy. Futhermore, we have exceedingly urgent problems and The Hydrogen Economy is something that is far in the future. I am not at all convinced that it will be an essential part of a long-range solution. I can see hydrogen as something important for special uses and special ways of producing it. I am advocating underground coal gasificiation. One of the products which can be isolated is hydrogen and because it burns cleanly, it could be used for some purposes although it is difficult to handle and it is dangerous because it is so light. It might be, it probably will become an ideal fuel for very big airplanes. But it has to be 4 PAGENO="0091" 85 handled with extreme caution and it will not come soon. We have to deal with the energy crisis that is now upon us. VO: There is a difference of opinion among experts about the potential of a m~E~ć hydrogen-electric economy, just as there is disagreement as to how much oil and gas this country can produce and how fast it can produce it. Despite these differences of opinion, hydrogen can provide a logical and economical transition into the nuclear-based 21st century for the consumer and the fossil fuel industry. In the short term, hydrogen can be readily derived from our most plentiful fossil fuel. . . coal. And in the long term, hydrogen can be produced from plentiful seawater by the use of nuclear heat. Isn't it about time we stopped ignoring our greatest natural resource and got our collective feet wet? 5 PAGENO="0092" 86 k Dr. Robert B. Rosenberg Vice Pre sident, Enginee ring Research Institute of Gas Technology Good morning. I'm Bob Rosenberg. As you are no doubt aware, there is a great deal of discussion about hydrogen these days. A lot of new terms are being used, - "Hydrogen Energy Systems, Hydrogen Economy," "Mixed Hydrogen-Electric Economy, " "Universal Fuel" and so forth. You are probably questioning whether any of these systems are for real. Do they refer to an idealized energy system centuries hence? Will they be useful to me in the coal, oil or utility business today, or just in the years ahead? We at IGT don't believe that hydrogen is an answer to all of our energy problems. Hydrogen is a secondary energy form. That means that some other energy source must be used to produce it. Thus, it is like electricity. However, once produced, hydrogen holds the promise of significant technical and economic advantages over other alternatives for various applications as we grow increasingly short of conventional fossil fuel and more dependent on nuclear energy. The particular advantage of hydrogen will relate to its relative simplicity and reactivity as a chemical feed stock. Or to its relative cleanliness in com- bustion as a fuel. Or to its relative simplicity in substitution in utilization equipment developed primarily for conventional fossil fuels. Or to its use as an intermediate energy carrier where its relative ease in transportation and storage might be used to advantage. We believe the broad possibilities of incorporating hydrogen technology into our basic energy business warrant our serious examination. 6 PAGENO="0093" 87 To provide us with a basic set of facts, we have invited several people here this morning who, because of their past and present activities, have a special knowledge of hydrogen technology and its possibilities. We have asked them to discuss with you the status of hydrogen technology develop- ments - what they see as the near and long-term role of hydrogen energy, particularly in the utility business - and what course of action you, as representatives of energy industry management, can take now to help assure that you realize the potential benefits of hydrogen energy. I will first call on Mr. John A. Casazza. Jack is a Cornell graduate and, as many of you know, is vice president of planning and research for Public Service Electric and Gas Company, Newark, New Jersey. Jack's company, under his direction,has been extensively engaged in hydrogen work for more than four years - both in analysis of how it can fit into its gas and electric distribution operations, and in actual development of equipment relevant to the needs they foresee. Not only is Public Service a current leader in hydrogen technology development in the utility business, but Jack tells us it is a real pioneer in the field. Ancient corporate records reveal that the firm known today as Public Service Electric and Gas Company once bore the name of Oxy- hydrogen Company of the United States. Thus he is backed with over 100 years experience when he talks this morning on `What Can Hydrogen Do For An Energy Company?" 7 PAGENO="0094" 88 John A. Casazza Vice President, Planning and Research Public Service Electric and Gas Co. Newark, N.J. WHAT CAN HYDROGEN DO FOR AN ENERGY COMPANY? Introduction In order to continue to meet the needs of this world we must use our resources wisely. These resources can be classified into three broad categories: natural, human, and capital. The natural resources consist of air, water, land and include such fuels as coal, oil, gas, and uranium. Our human resources, our scientists, engineers, and our skilled and unskilled labor are limited and must be used wisely. Our capital resources provide the tools through which our human resources can use our natural resources for the benefit of all the people of this earth. To conserve our limited capital we will have to make the best possible use of our existing energy systems. In using these resources we need to recognize that energy is closely tied to all mankind's need including food and water supply. A total system optimi- zation is needed. We cannot optimize the use of one resource to the detriment of the total system. In this process, it is essential that new technology be vigorously pursued and brought into use. Moving Targets and the Age of Uncertai~y The role of hydrogen and hydrogen-related technology in utility systems will depend on future growth, cost trends, new technology, and environmental requirements. Each of these areas presents rapidly moving targets for hydrogen as well as other energy forms. Examples of the speed of change are the rapid excalation in fossil fuel prices and the shortage of capital which has 8 PAGENO="0095" 89 re suited in more than 60, 000 MW of new electric generating capacity being delayed or cancelled in the U. S. A. since the first of the year. To be able to meet such uncertainties in the future we must maintain as many options and as much flexibility as possible in developing our energy systems. Why Hydrogen? We in PSE&G believe that hydrogen can play an important role in providing additional options and flexibility in meeting our future national needs from energy to food to transportation. Hydrogen can make possible the use of our nuclear energy resources for many purposes. With the intriguing future possibilities for the use of hydrogen, the funda- mental question becomes: When and how should we pursue the development and use of hydrogen technology in our energy system? Hydrogen can be produced from liquid and gaseous fossil fuels through catalytic oxidation and steam reforming, and from coal through partial oxidation and steam reforming. SNG plants and coal gasification plants have the potential, with some modification, of producing hydrogen. * It can also be produced from water, at the present time, through electro- lysis. Considerable research is underway on the thermochemical splitting of water to obtain hydrogen including the efforts at Euratom in Italy, the efforts of General Atomics in California, and the work at IGT. The production of hydrogen by this mechanism is not likely to occur before 1990. The Texas Gas Transmission Corporation is presently sponsoring work at the KMS Fusion Laboratories on the use of high-speed neutrons produced by laser fusion to split water molecules into hydrogen and oxygen. KMS predicts that it may be possible to produce hydrogen by such .a process in the late 1970s. Another possibility for the production of hydrogen is to use the neutrons that will be produced by a device similar to the two-component Torus device (TCT) presently under consideration for installaticn at the Princeton Plasma Physics Laboratory in 1979. The TCT project is expected to be funded by the U. S. Government at approximately $200, 000, 000. We in PSE&G felt several years ago that hydrogen research was justified if we were to develop the necessary technical expertise and the needed personnel to be able to cope with the problems of hydrogen in the future. Accordingly, we embarked on the following program: PSE&G Hydrogen Activities The approach selected for PSE&G in the area of hydrogen systems consists of both analytical studies and equipment and systems development. Analytical studies using parametric analysis to determine breakeven costs and key variables include: 9 PAGENO="0096" 90 1. Long-range system economic evaluations of hydrogen production from off-peak nuclear energy and dedicated nuclear plants. 2. Comparison of costs of hydrogen storage systems with alternate forms of storing energy. (Included in this work is a study of all potential forms of energy storage funded by a grant from the AEC.) 3. Integration of our electric and gas systems using hydrogen to take advantage of the seasonal diversity between these systems. 4. Studies of the future uses for hydrogen in making steel, for transportation, as a fuel, and in the production of fertilizer. 5. Studies of the installation of fuel cells in individual customer premises versus installation of fuel cells in sub stations. The equipment and systems development projects include: 1. Support of the fuel cell development program including the Pratt & Whitney 26 MW FCG- 1 development and the gas industry Target Program. The total PSE&G investment in fuel cell research will be $6, 800, 000 by the end of 1976. A three-phase fuel cell installation at the PSE&G City Dock Substation was the first use of fuel cells on a working electric utility system. 2. Developing improved hydrogen storage methods, specifically the metal hydriē~e storage concept working with the Brookhaven National Laboratory and the AEC. 3. Use of an electrolyzer_hydrogen storage fuel cell system in an actual power supply situation to obtain operating experience and costs, the vitally necessary training of people in the handling of hydrogen, and the data for `scaling up' to larger installations. A brief description of some of the results of this work may be of interest. ~y~1rogen Production From Off-Peak Nuclear E~gy One solution to the dwindling fossil fuel supply problem is the substitution of nuclear energy for fossil fuel energy. Because of variations in the patterns of usage of electric energy and the proportion of our electric requirements that will be provided from nuclear plants, we should have nuclear generation capacity available at certain off-peak times for use to produce hydrogen by electrolysis. Our studies have shown that this is a more economic approach and provides better utilization of capital than the installation of dedicated 10 PAGENO="0097" 91 nuclear plants for the sole purpose of electrolytic production of hydrogen. Further optimization of scarce captial resources may also be achieved through the use of the existing gas system to distribute hydrogen, possibly blended with natural gas. A key question is-how much nuclear off-peak energy will be available and when? Availability of Off-Peak Nuclear Energy A study of the availability of off-peak nuclear energy on the PSE&G system and the key factors determining it was made about a year ago. This analysis considered not only the daily and seasonal load cycles that are forecast, but also the limitation in minimum acceptable boiler loadings and the need to dispatch generation so as to provide adequate geographical area coverage. Figure 1 shows that once the nuclear capacity on an electric power system exceeds 30% of the total system capacity, rapidly increasing amounts of off- peak nuclear energy should become available with further nuclear generation additions. Since long-range plans for many systems call for about 50% of the generating capacity to be nuclear, extrapolation of this curve indicates that close to 10% of the total energy generated could be available in the form of off-peak nuclear energy. OFF-PEAK NUCLEAR ENERGY AVAILABILITY 6~2 AVAILABLE 0FF-PEAK NUCLEAR ENERGY (% OF TOTAL SYSTEM 3 ENERGY PRODUCED) I O 20 25 30 35 40 45 SYSTEM NUCLEAR CAPACITY (% OF TOTAL SYSTEM CAPACITY) FIGURE 1 Another way of illustrating this trend is shown in Figure 2. The ratio of average incremental peak energy cost to average incremental off-peak energy cost is shown to rise from 1. 5 in the mid-70s, to 7 by the year 2000, if no energy storage is provided. This tendency for the ratio between on-peak cost and off-peak cost to increase leads to greater desirability of using off-peak energy to provide some of the on-peak energy needs. The possibility of associated fossil fuel savings justifies increased attention to all forms of energy storage, not only hydrogen. 11 62-332 0 - 76 - 7 PAGENO="0098" 92 RATIO OF AVERAGE INCREMENTAL PEAK TO OFF-PEAK ENERGY COSTS ENERGY COST RATtO AVERAGE INCREMENTAL ( PEAK COST ~ AVERAGE INCREMENTAL OFF-PEAK COST FIGURE 2. "Electrolyzer" and- "Reformer' Fuel Cells Low-cost, off-peak power from nuclear plants could be used to electrolytically produce hydrogen which could be stored for later delivery to fuel cells during peak electric load periods. This concept of the "electrolyzer" fuel cell plant in which highly efficient electrolyzers would produce hydrogen needed by fuel cells was compared on a total cost basis with the "reformer" fuel cell where the fuel conditioning section or reformer converts hydrocarbon fuels to hydrogen gas which is then fed to the fuel cell power section. Figure 3 shows the breakeven capital cost differential for the "electrolyzer" fuel cell over the "reformer" fuel cell based on operating cost savings. In this analysis, the breakeven differentials in capital costs will just offset the operating savings or penalties. The curves show that based on off-peak energy costs in the order of 8 mills per kWh and fossil fuel costs approaching $1. 50 per million Btu, the "electro- lyzer'1 ~ue1 cell plant will have to cost in the order of $100 less per kilowatt than the "reformer" fuel cell plant to be economic based only on operating savings. For off-peak energy costs of 3 mills per kWhr (nuclear) and fossil fuel costs of about $2. 00 per million Btu, the "electrolyzer" fuel cell plant can be economically justified even if it costs $ 125/kW more than ~ fuel cells. YEAR 12 PAGENO="0099" `93 BREAK-EVEN CAPITAL COST DIFFERENTIAL FOR "ELECTROLYZER" FUEL CELL OVER THE "REFORMER" FUEL CELL 350 300 FOSSIL-FUEL COSTS, 250 `~,, $110' Blu 200 "N,~,I OPERATING HOURS' 2000 EFFICIENCIES: BREAK-EVEN CAPITAL 150 PRESENT TECHNOLOGY COST, $IkW (`ELECTROLYZER' 100 45,1j FUEL CELL SO `~ `REFORMER' 0 1. FUEL CELL -50 -100 -150 - AVERAGE INCREMENTAL OFF-PEAK ENERGY COST, MILLSIkWhr FIGURE 3 The "Electric/Gas Two-Way Energy Transformer" The PSE&G system is located in a mixed urban and suburban area. The pro- jected peak electric loads will be about 8, 500 MW in 1980, increasing to about 20, 000 MW in the year 2000. The generation system consists mostly of fossil- fuel steam and combustion turbine units. The major portion of additional capacity is being provided through the addition of large nuclear units. An extensive natural gas distribution system exists in the area which delivers approximately twice as many Btu's as the electric system. Our electric system has a pronounced summer peak while our gas system has a predominant winter peak. While changes of utilization practices in the future, possibly influenced by rate policies, could change this situation, loss of load diversity is not considered likely. Because of the potential savings from coupling electric and gas networks, we have made some preliminary studies of how two such systems could be integrated. Because of severe limitations in the supply of natural gas, our study was based on returning to the gas system at peak times all the energy removed from it at off-peak times. The extent of the diversity is limited by the cap- ability of the electric system to return energy to the gas system during the electric system's off-peak period. With this limitation, the maximum inter- change between the two systems is about 10% of the net annual energy generated by the electric system (or about 5% of the net annual gas system send-out). Figure 4 illustrates the basic study approach. First, the electric system* was assumed to be expanded independently with new generation capacity additions of 50% gas turbines and 50% nuclear generation. Similarly, the 13 PAGENO="0100" 94 gas system was expanded independently by adding gas sources and gas storage. ASSUMED ADDITIONS TO EXISTING ELECTRICAL AND GAS SYSTEMS FOR INDEPENDENT EXPANSION GAS TURBINES ELECTRIC SYSTEM NUCLEAR ELECTRIC GAS SYSTEM ASSUMED ADDITIONS TO EXISTING ELECTRICAL AND GAS SYSTEMS FOR COORDINATED EXPANSION GAS I TURBINES I ___________ (REDUCE~J ___________ FÜj~CLEAR I 5ELECTRIC LOAD TWOWAY ELECTRIC/GAS ENERGY ___________ TRANSFORMER ___________ F~-1 F GAS I SOURCES LOAD r GAS STORAGE (REDUCED) FIGURE 4 The integrated electric-gas-hydrogen system was formed by the link or connection between the gas and electric networks provided by a `two-way electric/gas energy transformer Figure 5 shows a conceptual idea of how such an energy transformer might function. The use of the electrolysis unit rectifier to also function as an inverter for the fuel cell, the condensation of water in the fuel cell exhaust to provide the water needed for electrolysis, and combining common components in the reforming and methanating equip- ment, all offer interesting possibilities for minimizing costs. Depending on various parameters, the break-even capital costs range from a low of about $ 150/kW to a high of about $600/kW of output from the fuel cell. 14 PAGENO="0101" Hydride Storage 95 CONCEPTUAL "TWO-WAY ELECTRIC/GAS ENERGY TRANSFORMER" With the need for energy storage at dispersed urban locations in energy systems of the future, we became involved in research and development in the use of metals hydrides for hydrogen storage. Metal hydride storage can be viewed as a desirable compromise between the low temperatures of hydrogen cryogenic storage and the high pressures of compressed gas storage. At the PSE&G Energy Laboratory we have in operation the first complete test facility for demonstrating the hydrogen energy storage concept on a utility system. In our facility, hydrogen is produced by a commercially available electrolyzer and stored in a hydride reservoir. The stored hydrogen is then released as fuel for a specially modified Pratt & Whitney 12. 5 kW fuel cell which supplies a portion of the electrical requirements of our laboratory building. This fuel cell was developed in the Target Program. The metal hydride storage unit is the result of AEC sponsored research at Brookhaven National Laboratory, where the Department.of Applied Science built the unit to performance specifications supplied by PSE&G. The reservoir con- tains iron-titanium particles, a silvery sand, which costs about $2/lb. The hydride is a chemical compound of hydrogen and iron-titanium. Iron-titanium is attractive because hydrogen as a gas can be combined or removed from the metal at moderate working pressures (500 psi) and within a few degress of ambient temperature. Hydrogen can be stored at densitites comparable to those used in liquid storage without the associated energy expenditures of 5 kWhr/pound for liquefaction. FIGURE 5 15 PAGENO="0102" 96 Preliminary tests of the unit at the Energy Laboratory have proven success- ful. Further testing will determine more precisely the relationship between hydrogen charging anddischarging and the temperature and rate of flow of the circulating water which is used as a heat transfer medium. Another important question is whether repeated charging and discharging cycles will cause de- gradation of the iron-titanium particles. This hydrogen test facility is providing valuable working expertise with hydrogen production, storage, and utilization. Hydrogen Versatility The versatility of hydrogen is especially attractive to combination utilities, like PSE&G, that provide both gas and electric service. It also provides a potential mechanism for electric and gas companies to coordinate for their mutual benefit. For example, studies indicate that up to 8 percent hydrogen could be added to the gas system to supplement our gas supplies without change in the gas distribution system. The potential use of hydrogen for transportation and the need for hydrogen to produce fertilizer offer intriguing additional possibilities. How to "Get There" We believe the best way to get started is in an area that has the potential for a short-term payoff such as PSE&G efforts with fuel cells and the hydride storage unit. If short-term efforts are successful, further development and progress will undoubtedly evolve. Future steps needed are: 1. Extensive research and development to improve efficiencies and to decrease capital costs of hydrogen production, storage, and distribution facilities. 2. The continuing growth of the nuclear industry for producing hydrogen either electro- or thermo-chemically. (The recent postponment of nuclear commitments throughout the country will delay the availability of off-peak nuclear energy for the production of hydrogen.) 3. A significant effort by the gas industry to determine the ability of existing gas transmission and distribution systems to transmit hydrogen both alone and blended with natural gas. 4. Increased government and industry funding of hydrogen R&D activities. 5. Social acceptance of a new energy system through public information and education. Safety aspects should be frankly discussed. 16 PAGENO="0103" 97 Energy conversion systems not dependent on fossil fuels will be the energy conversion systems of the future. Certainly, in the next 20 years, the need for synthetic or so-called secondary fuels will increase. Our diminishing fossil fuel reserves and increasing costs coupled with environmental require- ments should provide the incentives for the broad expenditures for research and development work needed to develop uses for hydrogen. In the long-term future, which could range anywhere from 20 to 100 years,. as fossil feedstocks become scarce, nuclear energy will probably be used to produce hydrogen from water on a bulk scale either by nuclear or thermochemical means. Nuclear and solar devices will become the primary sources of energy while electricity and hydrogen will co-exist as the most important secondary energy forms. Conclusions While the role of hydrogen in the future is not yet clear, a number of conclusions can be drawn at this time: 1. We cannot afford to abandon our existing energy systems. 2. Hydrogen has the potential to complement both our electric and gas systems as well as helping in the solution of the world's transportation and food problems. 3. Hydrogen's future role will result in the need for more nuclear power, and possibly more electricity, than indicated by current projections. In the past, we have reacted to change. In the future, we need to cause change. We need to prevent fires - not put them out. We need to move for- ward vigorously in determing hydrogen's future role. ROSENBERG: Thank you, Jack, for setting the perspective on hydrogen based on the work you are doing at Public Service. The concepts you described for achieving higher overall efficiency by. interfacing your gas and electric systems with hydrogen are new to most of us here today. Moreover, your points on potential near-term applications of hydrogen are very important. Next I would like to introduce Mr. John E. Johnson. Mr. Johnson is product manager for hydrogen, Linde Division of Union Carbide Corporation. He has been active in liquid hydrogen technology since 1958, including design and operational experience on all Linde liquid hydrogen plants. Linde of course has been marketing industrial gases including hydrogen for many years. Probably the most significant fact to our program this morning is that Linde was the prime supplier of hydrogen to the space program. This presented it with the unique problem of producing, distributing and handling hydrogen on a scale never before undertaken. It is from the vast experience gained in this endeavor that John will discuss "The Statua of Hydrogen Technology Application." 17 PAGENO="0104" 98 John E. Johnson Product Manager, Hydrogen Union Carbide Corporation Linde Division New York, N.Y. THE STATUS OF HYDROGEN TECHNOLOGY APPLICATION The prospects for using hydrogen as an energy carrier has intriguing possibilities, particularly in view of the accomplishments already in hand for solving the many practical problems that would be involved with its intro- duction. I hope that I can give you a brief outline of this considerable cap- ability already in existence. Hydrogen has been produced and distributed as an industrial gas for about seventy-five years, which has resulted in the accumulation of an extensive technology inventory. A significant operating scale has already been achieved, and hence it is possible to easily extrapolate this experience to the larger re- quirements of energy distribution. Safety standards have been developed and tested in applicable operating environments. The data base available is cer- tainly sufficient to assess the feasibility of the possible introduction scenarios. Accurate economic evaluations can be developed and the problems that need to be solved are also definable. Initially, hydrogen was distributed as a compressed gas in the familiar "K" cylinder and tube trailer. Operations were carried on at a very modest scale until the late fifties when the space program provided the impetus to undertake and solve the problems of large-scale production and distribution of hydrogen. The Centaur Rocket was the first significiant application of "hydrogen energy. " 18 PAGENO="0105" 99 The requirements of rocket technology for hydrogen in its liquid state im- posed engineering standards which exceed those of energy transmission via hydrogen. Unique engineering solutions were required in order to make the general availability of the fuel that transported man to the moon a reality. Hydrogen separation processes had to be developed to reduce impurity contents in hydrogen to less than one part per million to permit its lique- faction. The then largest cryogenic systems had to be provided to accomplish the liquefaction. This capability is exceeded today only by the large base load LNG systems installed overseas. And, finally, the establishment of a full- scale storage and distribution system for liquid hydrogen capable of operating on a nationwide basis was required. This resulted in the development of advanced insulation techniques and solved the basic problems of interfacing hydrogen in the industrial/public environment. Although some liquid hydrogen was produced during and shortly after World War II in conjunction with experiments in high energy physics and fusion, the advent of the space program motivated the recent general interest in hydrogen. The Air Force constructed the first large-scale liquid hydrogen plant in Florida in 1958 to provide needed propellants for a then classified Pratt and Whitney rocket engine program. Also, during this period, aeronautical applications for hydrogen fuel were in an advanced development stage by Lockheed for a high-flying reconnaissance aircraft. With the requirement of liquid hydrogen for the subsequent NASA space program assured, the industrial gas industry provided the facilities to support these efforts. Union Carbide built the first industry-financed 3M cfd facility at Torrance, California in 1960. This was followed quickly by larger industry financed 12M cfd facilities in California and Louisiana. By 1965, over 80M cfd of capacity had been con- structed and since then, approximately 100 billion cu. ft. of hydrogen have been distributed in support of the space program and other industrial requirements. This buildup of capacity culminated in 1964 with Union Carbide's - and the world's - largest liquid hydrogen plant which was located in Sacramento, California. This 2AM cfd facility consumed 30 megawatts of electrical energy and 12 million cu. ft. /day of natural gas. The hydrogen production capability of this facility is approximately 1/10 the scale of today's proposed substitute natural gas plants. But, since these synthetic fuel plants are also to be multiple trains, the accomplishment at Sacramento is very significant in evaluating the scale-up problems involved in building a large hydrogen production facility for energy distribution. The completion of the Apollo program resulted in dismantling much of this initial liquid hydrogen capacity, but half still exists to serve increasing industrial requirements for hydrogen. Additionally, two facilities have been developed in the northeast to serve the industrial requirements. Today, hydrogen is distributed virtually in every state in the Union, and the convenience of liquid hydrogen to distributors and users alike is making obsolete many of the older gaseous pro- duction and distribution systems. Hydrogen is used for a variety of applicaticins, including reducing atmos- pheres and reducing agents, chemical hydrogenation, and clean combustion 19 PAGENO="0106" 100 applications. Many industries are dependent on obtaining this unique material which is used for the manufacture of glass, electronic components, food and drug products, reduction of heavy metal oxides, metallurgical finishing processes~ and even in synthetic gem manufacture. The next challenge for hydrogen will be to fuel NASA!s reusable space transport system - the Space Shuttle. We should review some of the accomplishments in hydrogen technology that were advanced in support of the space program and which will provide much of the needed technological base to support future development of hydrogen energy. INDUSTRIAL APPLICATION FOR DISTRIBUTABLE HYDROGEN REDUCING REDUCING cHEMICAL CLEAN ATMOSPHERE AGENT HYDROGENATION COMBUSTiON FLOUT GLASS MANUFACTURING S1LICON ELECTRONC ~ COMPONENTS TUNGSTEN CARBIDE URANTJM MARGARINE TND MANUFACTURING FATTY SODS PRODUCTION DRUG SYNTHESIS Hydrogen was manufactured by the process of steam reforming of natural gas where over half the H2 was extracted from water. This technology has found continuing application in the present large scale hydrogen production units which have become common in oil refineries to supply their ever-growing needs for hydrogen. Many of the answers to the questions on material selection and operations analysis for the water splitting cycles will be provided from this type of experience. The purification of hydrogen to one part per million was first carried out in cryogenic units which dissolved impurities from the hydrogen. Liquefied methane and propane, operating at _2500 F were used as solvents to remove impurities. Because of the great flexibility of the cryogenic processes to selectively remove many varieties of impurities, they will find application in recovering hydrogen produced from the various energy resources which will be employed in the future. Subsequent developments permitted carrying out this difficult purification requirement in one step at ambient conditions, employing the unique proper- ties of Linde Molecular Sieve adsorbents to trap impurities. Although adap- tive only to smaller scale operations, PSA adsorbers could typically find SYNTHETIC GEM MANUFACTURING 20 PAGENO="0107" 101 application in conjunction with fuel cells by supplying pure hydrogen from a hydrogen-rich low-Btu fuel gas system. Large hydrogen compressors, which are necessary to develop the refrigera- tion requirements for liquefaction, also simulate the requirements for moving this fluid in pipeline service. The 11, 000 H. P. compressors at our Sacra- mento plant were the world's largest reciprocating compressors, and they represent the best experience to demonstrate large machine design capability in H2 service. Over-the-road transportation of liquid hydrogen required the development of high performance insulations and high-quality vacuum-insulated tanks. This technology has been advanced to the point of full-scale over-the-road capability which is similar in many aspects to your LNG operations. Present industrial customers requiring hydrogen today routinely store liquid at their facilities. These customer stations are serviced weekly by over-the- road trailers which may travel as much as 400 to 500 miles to deliver their product. In order to inventory stores of liquid hydrogen convenient to customer centers, Linde operates the only nationwide rail distribution network to link its inventory centers with production facilities. Railcars (28, 000-gallon) commonly move liquid hydrogen from Los Angeles to New England without venting any of their product on trips that may take two weeks or more. Auto- matic devices can safely dilute the hydrogen below its flammability limit in air and discharge the product unattended in the event of mishap. The develop.. ment of this extraordinary capability clearly demonstrates the potentiality for safe design of future hydrogen energy transmission systems. Although hydrogen was originally viewed as a very dangerous material, experience has surprisingly shown that in many ways its properties are more desirable than other fuels. The basic design and operating philosophy, as with any fuel, is to contain the material and prevent its possible admixture with air and to ventilate those areas where containment might fail - basically, fix leaks and prevent flammable concentrations from accumulating. These are fundamental rules in dealing with any fuel. Hydrogen has a wide flammable range, but its lower limit is not much different from other fuel gaSes; hence, the initial propensity to ignite is similar. Although more easily ignited, hydrogen generally does not explode, but burns rapidly. Its high characteristic diffusivity increases the tendency to dilute below flammable levels unless the area is substantially enclosed. Flames exhibit low radiation levels and the buoyancy of the fuel causes it to burn vertically which minimizes secondary effects in a hydrogen fire. To date we have had only one minor plant damage incident where hydrogen was involved. Similarly our accident record in over-the-road and rail service is essentially no different from the other cryogens we transport. Product involved accident frequency rates are only in the order of five incidents per 100, 000 trips. In fifteen years of operation, I know of no liquefied~hycirogen_ involved fatalities within the industrial gas industry. 21 PAGENO="0108" 102 Quality control is the essence of any hydrogen system design. Because of the low molecular weight and high diffusivity, hydrogen tends to leak more readily from its container than other fuels. But fuel leakage, under any circumstance represents a problem to a fuel gas distributor that must be solved. Specifications for construction materials must be carefully drawn to avoid porosity in construction materials, particularly in valve body castings; and joints must be adequately tested to insure their integrity. Seals on mechanical equipment should be under inert positive pressure and vented to prevent back- ward in-leakage of air. - Ventilation is the major defense for preventing a catastrophe in the event of a serious escape of hydrogen. Adequate space concepts, inerting and dilution techniques, and detection devices to give early warning of a mishap are the major methods to cope with a spill. Finally, ignition source avoidance repre- sents an additional line of defense. Hydrogen is capable of changing the metallurgical properties of many common construction materials, particularly steel, by a process known as embrittlement. The characteristics of this phenomenon are generally under- stood; and designs have been proven over years of operation which can demon- strate their adequacy. The basic design strategy is to select embrittlement- resistant steels and alloys, and prohibit operating pressures in excess of their known embrittlement limits. Certainly the totality of conditions which cause embrittlement phenomenon are not known, but experience to date provides substantial background on which to propose future designs. The introduction of large-scale hydrogen energy systems will present new problems which will require further work to assure safe performance in energy distribution systems. The application of this industrial hydrogen experience base into the technological frontiers of energy distribution is already pro- ceeding. As with the introduction of liquid hydrogen into industrial applica- tions, much work must be done to gain an acceptance by energy consumers to utilize hydrogen. In coursing through the labyrinth of potential opportunities, the energy-intensive industries such as electric power distribution, aviation, and steel, are beginning to discover potential benefits in adopting this energy source. Hydrogen, as a secondary energy carrier, is not likely to be the lowest cost fuel; therefore, its other potential benefits must be exploited. In addition to the initially projected environmental benefits of employing hydrogen, tantalizing prospects for efficiency improvement in the various hydrogen energy conversion processes are now being reported which will accelerate the achievement of economic parity with conventional fuels. Overcoming the current limiting technologies in these various beneficiated applications, work on which is just now commencing, is the next requirement for motivating customer acceptance and proving design acceptability. Risk analysis must be performed as present capability is scaled up to the vastly increased require- ments of energy systems. Typical questions that are yet to be resolved in respect to energy system design are: Will unsuspected embrittlement phenomena occur due to some unexperienced feature of a large hydrogen energy transmission system? PAGENO="0109" 103 MOTIVATING CUSTOMER ACCEPTANCE OF HYDROGEN FUEL INITIAL LIMITING INITIAL APPLICATION BENEFIT TECHNOLOGY SOURCE ELECTRICITY A~5~ EFFICIENCY FE COAL/REFUSE DISTRIBUTION INTERMEDIATE ~ ~ CYCLE EFFICIENCY DISTRIBUTION AVIATION INCREASED FLIGHTWORTHINESS COAL HYDROCARBONS EFFICIENCY NUCLEAR IRON AND STEEL.~~Z Ji1~ EFFICIENCY COAL/REFUSE EFFICIENCY NUCLEAR What are the effects of large quantity spills which could occur from energy delivery systems? Are present gas distribution systems designed to permit hydrogen admission? Can they be easily adapted or must they be replaced? What is the life expectancy of components before failure? Are the failure modes safe? What additional precautions must be instituted if hydrogen fuel is to be introduced to the public sector? As work proceeds toward prototype projects to gainexperience and do the required reliability proofs, what present H2 energy system component avail- ability deficiencies exist? The major shortcoming will be in the area of gas compression. Much needs to be done to overcome the awkwardness of the reciprocating technology existent. Hydrogen compression in rotating machinery will require advances in large or high-speed dynamic machines to gain parity with other fuel transmission systems. The ultimate scale of hydrogen production equipment based on laws of diminishing return needs also to be determined. And, of course, an efficient process for the direct production of hydrogen from nonhydrocarbon energy sources remains a basic requirement. Potential benefits included, and introduction costs excluded, hydrogen could be an economical energy carrier soon. Neither its exotic reputation nor economics of product availability should be used as a basis for deferring develop- ment efforts. In addition to possibly obtaining hydrogen from off-peak power, much of the effort in converting coal to substitute high-Btu gas involves hydro- gen technologies. Both the Lurgi and Koppers/Totzek Processes are prolific hydrogen producers and can be as easily and efficiently adapted to hydrogen manufacture as methane. 23 PAGENO="0110" 104 Another possible way of producing hydrogen to serve potential introduction schemes is the PUROX process which is currently being developed by Union Carbide to convert refuse to a usable fuel gas. Refuse is charged into a vertical shaft furnace and reduced with oxygen to a slag and 300 Btu/cu. ft. fuel gas con- sisting mainly of carbon monoxide and hydrogen. This process can be easily adapted to pure hydrogen manufacture. The technology soon to be available from processes such as these can economically supply the initial quantities of hydrogen to imp'ement and develop critical early stages of hydrogen energy demonstration until hydrogen can be competitively derived from nonhydrocarbon energy sources. Another major benefit of hydrogen in the nuclear age to the energy industry has been the projected benefits of achieving economic, and environmentally benign, energy distribution. The strategy for obtaining economical underground energy distribution is to maximize system capacity and maximize efficiency of energy conversion which then reduces total energy flow to the customer. Electrical transmission with its low energy flow requirement is striving toward these goals by research with superconducting cables. Hydrogen also offers opportunities to increase energy flow in a relatively simple conduit, because of the potential for high energy conversion efficiency relative to other fuels that might be conveyed underground. Although the tendency is to view these distribu- tion systems separately, a major payout may be in a yet unexplored synergism between them where the cryogenic properties of liquid hydrogen could benefit superconducting electrical transmission, while sharing of energy generation facilities would benefit the coproduction of a more storable energy form as liquid hydrogen. It is interesting to note that at the start of this century, the first requirements for hydrogen on an industrial scale were for use in aeronautical research where the unusual lifting properties of this lightest gas were sought. The initial require- ment for industrial hydrogen was obtained as a by-product from the oxygen generated by electrolysis for the then newly emerging oxy-acetylene flame applications. Sabatier developed the first catalytic process for hydrogenating organic compounds. Other developments quickly followed, culminating in the Haber process for producing ammonia in 1913 - which demonstrated the cap- ability for large-scale handling of hydrogen. Hydrogen now dominated require- ments, and new methods were sought to produce this resource because of the inability to dispose of the excess oxygen from the electrolyzer profitably. Pro- cesses to crack water, using coal, soon became prominent. A cryogenic ex- traction process was even developed in Germany to separate hydrogen from "water gas" that was produced commonly in the "gas houses" of that era. By the end of World War I, electrolysis had become outmoded and hydrogen pro- duction became totally reliant on the lower cost and increasingly available hydro- carbon energy resources. Now that the unique characteristics of hydrogen as an energy carrier need to be explored further, a new era of technology development is at hand. As with hydrogen's early introduction, the aeronautical sciences, electrochemical technology, and reduction processes are likely to provide the early impetus to expand the technology base. Fossil sources, no doubt, will supply the energy for manufacturing the initial requirements of hydrogen until the more refined non- hydrocarbon energy conversion systems based, first, on nuclearenergy, begin to supplement. 14 PAGENO="0111" 105 I have had to cover an awful lot of ground in a short time. But I hope you now realize that there is a lot of ground to cover, and it seems to have been covered more than once. Many of the technologies of hydrogen energy systems are already in hand and not really `new." Extending the current technology limitations is the first requirement to develop the potential of hydrogen as a future energy carrier. These extensions can be accomplished by: 1. Effective demonstration of the benefits that accrue to potential users of H2 (which are now merely gleams in the eye of the research community) so the existent technology may be rationally extended to energy dimension scale, and: 2. Improvement of the technology to extract hydrogen from water efficiently, from various non-hydrocarbon energy resources, in order to improve their respective interchangeability, storability, and portability, while increasing the competitive - ness of these resources as a viable alternative to our de- creasingly available fossil resources. ROSENBERG: Thank you, John. Although hydrogen is a somewhat unknown quantity for most of us, it is obvious from what we have just heard that it is a common day in and day out business with you. For most of us, the mere mention of hydrogen is immediately associated with overtones of safety questions. Certainly the experience of Linde is ample testimony that practical and safe methods can be established for large-scale use of hydrogen just as well as they have been for other fuels with which we are more familiar. Next we would like to turn our attention to the questions of "How much will it cost?" And, "When might we expect hydrogen to play a significant role in the Energy Picture?" Dr. Kenneth C. Hoffman, who received his Ph. D. from the Polytechnic Institute of Brooklyn, is head of the engineering and systems division at Brookhave National Laboratory, and has been engaged in a number of hydrogen research projects. Under sponsorship of the Atomic Energy Commission, Dr. Hoffman has developed models of competitive systems for producing secondary energy and transporting it to the ultimate consumer. These are the systems which are frequently talked about today all- electric economy, hydrogen economy, and mixed hydrogen-electric economy. With the use of his models Dr. Hoffman has conducted what is undoubtedly the most systematic comparative economic analysis of these systems to date. Time will not permit him to describe his methodology and techniques in de- tail. However, we have asked Dr. Hoffman to summarize the key conclusions of his studies as they pertain to the "Economics of Hydrogen Energy Systems." 25 PAGENO="0112" 106 Dr. Kenneth C. Hoffman Brookhaven National Laboratory Upton, New York ECONOMICS OF HYDROGEN ENERGY SYSTEMS* In evaluating a new energy technology, attention must be given to the pros- pective economic characteristics of that technology, and the economic circum- stances under which that technology might be an important factor in the energy system. Given the hazardous nature of economic analyses for even existing technologies in a period of rapidly changing prices of labor and material inputs to production, it is important that the inherent uncertainties of economic analyses be recognized. The analysis of long-term options such as hydrogen energy systems must be broad in scope, encompassing questions of environ- mental impact, efficiency, and cost. The definition of a range of cost and efficiency parameters over which these systems might compete with alter- native technologies is required to establish objectives for a research and development program. Any technological option that is at an early stage of development should also be viewed in terms of the diversity and versatility that it can add to the energy system. Hydrogen, as a secondary energy form, is compatible with our abundant domestic resources including those that are renewable and can be used in virtually all of the functional end uses that are of interest. Since the more abundant U. S. resources of. nuclear, coal, solar and geothermal energy may be used most effectively to produce electricity, the basic issue *Work performed under the auspices of the U. S. Atomic Energy Commission. 26 PAGENO="0113" 107 is the definition of the complementary roles of hydrogen and electricity in exploiting these resources. There are several end-uses that are best served by electric energy and several that are clearly best served by a portable chemical fuel such as hydrogen. In view of the rather unique advantages of each energy form, it is unreasonable to talk of an all-electric or all-hydrogen economy. Attention should focus more clearly on the question of the partition of the energy system between electric and non-electric energy forms. At present, roughly 25% of the energy resource consumption in the U. S. is for the generation of electricity. This fraction has been projected to grow to nearly 50% by the year 2000, due primarily to the demand growth in those sectors that are totally reliant on electricity. Recent financial difficulties in the utility industry will clearly affect this trend if they persist. The balance of the energy resources are consumed as coal, oil, and gas at the point of end use. As these oil and gas reserves are depleted along with the more easily ex- ploited coal reserves, a substitute general-purpose fuel such as hydrogen will be needed. The partition of the energy system will clearly depend on the relative price and efficiency at the point of end use of this fuel and of electric power. It is instructive to consider the "efficacy" of hydrogen relative to electricity in specific end uses to be represented by the ratio of the units of electrical energy required to substitute for one unit of hydrogen. This parameter ranges in the limit from zero for those end uses where hydrogen is difficult to use to infinity for those end uses where electricity is not easily used. End uses such as aircraft fuel and petrochemical materials, where hydrogen has some unique properties-will have a high efficacy ratio, while in applications such as space heating, the efficacy ratio might be around one-fourth assuming that one- fourth of a unit of electricity operating a heat pump could replace a unit of energy in the form of hydrogen used in a burner. Figure 1 illustrates the possible range of partition of the energy system and some typical end use efficacy ratios. Hydrogen is already being used in several high efficacy ratio applications in industry where its properties are unqiue. An area toward the top of the bar chart may be defined where hydrogen has a clear advantage. Similarly, a set of end uses may be specified where electricity has a unique advantage. The use of one or the other secondary energy forms for those end uses in the competitive zone will depend to a great extent on technological progress in the electric sector and in hydrogen energy systems. If the demand for non-electric energy forms continues to increase, it is apparent that a transition must be made from fossil fuels to some non-fossil synthetic fuel. Figure 2 shows a long-run projection of the role of hydrogen in this transition. This projection was made by. Professor Alan Manne using an energy system optimization model that determines the minimum supply cost and fuel mix given a set of overall resource constraints and input fuel costs. In the analysis it is assumed that non-electric demands, grow at the rate of 2% per year. It is seen that hydrogen comes in rather strongly as oil and gas are depleted and as the production of other synthetic fuels from coal reaches a peak. The hydrogen required for coal conversion processes is not reflected in the hydrogen production curve. The hydrogen may be produced by electrolysis or by an advanced process such as the thermochemical 27 62-332 0 - 76 - 8 PAGENO="0114" 108 PORTION OF ENERGY SYSTEM BETWEEN ELECTRIC AND NON-ELECTRIC ENERGY FORMS FRACTION OF TOTAL DEMAND 100% EFF1CACY RATIO: INFINITY NON-ELECTR1C RAILROAD AIR-CONDITIONING ELECTE1C AFPIJANCES ELECTRIC DRIVE 0% EFFICACY RATIO: ZERO FIGURE 1 decomposition of water using a high-temperature reactor (HTR) as the heat source. NON-ELECTRIC ENERGY DEMAND TRENDS 14C DEMAND: 2% 120 - GROWTH RATE D~N~~tu / FR :: SHALE OIL C' I I `l- IMPORTS 1970 198.5 2000 2015 2030 2045 YEAR FIGURE Z The resource demands in the electric sector are not shown here; however, this sector relies heavily on coal in the intermediate term and on nuclear fuel in the longer term. Additional nuclear capacity is required to produce the quantities of hydrogen employed in the non-electric sector. It is anticipated that the course of implementation of hydrogen in the energy system may proceed in the following sequence: 1.Industrial uses for fertilizer, petrochemicals, and coal conversion, 28 PAGENO="0115" 109 2. Use by electric utilities for peak shaving with fuel cells and as a supplement to natural gas, 3. Transportation fuel in aircraft and fleet vehicles, and 4. Residential and commercial use as an alternative to all-electric homes and where load factors are poor. Estimates of the possible level of implementation in these applications are given in Figure 3 for the years 1985, 2000, and 2020. These implementation levels represent the quantities of hydrogen used in each of the sectors and are based on estimates of market penetration. The industrial usage includes hydro- gen for ammonia synthesis and other chemical uses but does not include the - hydrogen used for coal gasification and liquefaction. The total energy consump- tion in 1970 and projections for future years are included for comparison pur- poses. This projection of hydrogen usage is more conservative in the long run than that given in Figure 3, but still represents a significant role in the energy system for this fuel. In addition to depending on technological progress in the production and delivery of hydrogen, these implementation levels depend on the attainment of satisfactory levels of reliability and safety in early applications. HYDROGEN USAGE ESTIMATES (1015 Btu) 1970 1985 2000 2020 1 2 4 10 0.2 1 4 0.5 2 6 INDUSTRY UTILITY TRANSPORTATION RESIDENTIAL AND COMMERCIAL 1 5 TOTAL HYDROGEN CONSUMPTION 1 2.7 8 25 TOTAL U.S. ENERGY CONSUMPTION 70 115 175 250 FIGURE 3 Despite the hazards inherent in economic projections, some estimates of the cost of hydrogen energy systems and the effect of technoiDgical advances are required. Figure 4 summarizes the cost and efficiency for various pro- cesses for the production, transmission, and storage of hydrogen. The characteristics of current and advanced technologies are indicated for each process. The cost of hydrogen depends on the technical and economic characteristics of a sequence of processes that convert a primary resource, e. g., nuclear or solar energy, to electricity or heat which is used in the hydrogen production step. The hydrogen must then be transported to the point of use by pipeline or some other means. Consideration of this sequence of processes that deter- mine the cost of hydrogen and the overall efficiency with which it is produced requires a systems approach. 29 PAGENO="0116" 110 PROCESS COSTS - HYDROGEN ENERGY SYSTEMS (CURRENT TECHNOLOGY- ADVANCED TECHNOLOGY) PRODUCTION EFFICIENCY COST ELECTROLYSIS 0.7-0.9 150-50$/kW ELEC. GENERATION- -0.23-0.45 650-500 $/kW ELECTROLYSIS THERMOCHEMICAL 0.25-0.5 LIQUEFACTION 0.7-0.8 2.00 $1106 Btu TRANSMISSION EFFICIENCY COST GAS PIPELINE 0.9 8 C/106 Btu -100 MILES LIQUID 095 15C/106 Btu-100 MILES STORAGE (106 SCF H2) EFFICIENCY COST GAS (2500 psi) 0.9 $9 X 10~ LIQUID 0.7 $8 X 106 HYDRIDE 0.95 $4 X iO~ FIGURE 4 Figure 5 presents four alternative energy conversion and delivery systems in a flow diagram format that has been widely applied to energy technology assessment. The flow diagrams indicate the sequence of processes that are required to deliver a Btu of energy in the form of electricity or hydrogen. Each process is represented by a link in the trajectory and the input energy to each is indicated above the link. The efficiency of the processes is given in the parentheses. The all-electric system includes a nuclear power plant operating at a plant factor of 0. 5; e. g., over a one-year period the plant produces only about half of the electric energy that it would were it operated at rated power for thc same period. The reference transmission technology in this case is assumed to be over head high-voltage AC. The use of underground transmission would cause a significant increase in the cost of the delivered electricity. Superconducting technology provides an alternative transmission technology that may be feasible in the long term. If successful, this technology would provide the capability of moving very large blocks of electric power over long distances through limited rights-of-way without incurring an excessive cost penalty. 30 PAGENO="0117" 111 ALTERNATIVE HYDROGEN SUPPLY SCHEMES - DELIVERED PRIMARY TRANS- COST CONVERSION H~PROD. MISSION DISTRIBUTION (8/10' Btu) ALL ELECTRIC ELECTRIC; PF:O.5 22 (0.5) 1.1 - 1.1 (0.9) 700 (ELECTRIC) MIXED SYSTEM 4 ( ELECTRIC; FF0.5 700 (ELECTRIC) HYDROGEN 2.4 (0.51 1.2 OFF-PEAK *---------------------`-<~0.8) ELECTROLYSIS ~ 2 46 (HYDROGEN) ALL HYDROGEN ELECTROLYSIS; 2.8 (0.5) 1.4 10.8) 1.1 (0.91 5 50(HYDROGEN) DEDICATED PLANT THERMOCHEMICAL; 2.2 (1.0) 3.2 (0.5) 1~1 10.9) 450(HYDROGEN) NO FEASIBLE THERMOCHEMICAL CYCLE HAS BEEN DEVELOPED; THEREFORE, COST ESTIMATES MUST BE CONSIDERED AS R&D OBJECTIVES. FIGURE 5 Thus, the technology might provide for more flexibility in the siting of large power complexes, but would not result in any significant decrease in the delivered cost of electric power. In the mixed system, the nuclear plant is employed to deliver electricity with a plant factor of 0. 5 as in the previous case, but it also operated during off-peak periods to produce hydrogen by the electrolysis of water. The plant is assumed to operate at an overall plant factor of 0. 8 in delivering both electricity and hydrogen. The all-hydrogen cases consider dedicated plants delivering only hydrogen that is produced by two alternative processes, electrolysis and thermochemical water splitting. The thermochemical process requires a high-temperature reactor (HTR) operating at about 1700* F as a heat source. To put both electricity generation and hydrogen production via thermochemical water splitting on a common basis, it is assumed that the high-temperature reactor, with a conversion efficiency of 50% for electric generation, is available for both applications. The delivered costs indicated on Figure 5 include transmission and dis- tribution cost elements that are appropriate for large-scale industrial users. It may be seen that hydrogen can be delivered at a lower cost than electricity from a dedicated nuclear plant using either electrolysis or thermochemical water splitting. The latter is of course a speculative technology and the cost estimates are quite uncertain. Hydrogen produced electrolytically from off- peak nuclear power could be delivered at an especially low incremental cost; however, only limited quantities would be available depending upon the extent that nuclear capacity exceeds normal base load requirements. The input energy resources to each energy system indicate that the hydro- gen systems are generally less efficient than the electric system. The one exception is the thermochemical production system which will be competitive with electricity if a 50% production efficiency can be attained. 31 PAGENO="0118" 112 Upon examination of the ultimate need for some non-fossil synthetic fuel and considering the near-term requirements for hydrogen in several industrial applications, it is apparent that an expanded research effort on production, storage, and transmission technologies is warranted. The current Federal R&D expenditures on hydrogen energy systems are estimated in Figure 6. FEDERAL R&D ON HYDROGEN ENERGY SYSTEMS ($1000) FY 1975 PRODUCTION 500 TRANSMISSION 100 STORAGE 500 END USES UTILITY 850 TRANSPORTATION 200 SYSTEM STUDIES 550 TOTAL 2700 FIGURE 6 Progress in improving the efficiency of hydrogen production could increase its role in the energy market. On the other hand, the successful development of such technologies by electric vehicles with high-performance batteries or economical heat pumps would result in an increased role for electricity. A balanced R&D program encompassing effective programs in all of these areas will ensure that the full benefits of these complementary secondary energy forms will be reaped. ** ** ROSENBERG: Thank you, Ken, for condensing the results of your extensive efforts into a very clear picture of how and when hydrogen could fit into the future U. S. energy mix. You have defined some very obvious economic incentives which should be of particular interest to utility management. I am sure that we all have a better perspective now of where hydrogen may fit. Many of you know my associate, Dr. Derek Gregory, who is the next speaker on our program this morning. Derek is director of energy systems research at IGT. In this capacity he has published broadly in both the technical and popular press on the subject of hydrogen energy. During the past several years, he has successfully directed and personally contributed to more than a dozen research programs on various aspects of hydrogen from both industry and government. Derek also serves on several national advisory committees and has had the opportunity of reviewing both the objectives and plans of most of the organizations that are now active in the hydrogen field. From this vantage point we have asked him to discuss his views of "What We Can Do Now as Utility Industry Management and Government Planners." 31 PAGENO="0119" 113 Dr. Derek P. Gregory Director, Energy Systems Research Institute of Gas Technology WHAT WE CAN DO NOW AS UTILITY INDUSTRY MANAGEMENT AND GOVERNMENT PLANNERS I want to address the question of what the utility industry and the Govern- ment should be doing now about hydrogen energy. But before that, let me address a question that must have occurred to you; that is, why should the gas industry consider at all a change from natural gas, supplemented by SNG, as its basic commodity? In a joint energy policy statement from the five major U. S. energy industry trade associations, the need for energy growth was stressed. They said, "For the benefit of all segments of our society, we must assume a growing energy requirement. Any substitution of existing energy sources with new ones should be capable of sustaining a high growth rate for a considerable period. Although SNG from coal, shale, and biomass are extremely important new energy sources, they may not be capable of sustained high growth for periods extending well into the next century. An additional and growing source of energy will be required to supplement these supplies. The previous speakers have made a good case to suggest that hycTrogen made from nuclear energy could be the means of providing this supplement. Let me emphasize the point made by Ken Hoffmann that hydrogen is an alternative to electricity. It should be compared with electricity on the basis 33 PAGENO="0120" 114 of cost and usefulness, and can co-exist with electricity in a combined energy transmission system. In the future we will nothave enough fossil fuels to meet our needs. This shortage is already having an effect on the gas industry. Because of this, we will not have the choice between fossil fuels and hydrogen, and we should there- fore not place emphasis on a comparison of the cost of hydrogen with today's conventional fuel prices. The choice we have for the future is hydrogen, or electricity. Although it now appears that hydrogen may not actually enter widespread use as a fuel gas until after the year Z000, there are many special applications of hydrogen likely to become attractive in a shorter term. Several combination utilities like Jack Casazza's have already begun work on these. We must not take the attitude of doing nothing and waiting until the time when huge augmentation of natural gas by hydrogen is economically justified. The approach to this point will require a well-planned and controlled introduction of hydrogen over many years. We waited too long - until the natural gas supply actually stopped increasing-before we embarked on a sizable SNG program, and this delay re- sulted in the present unavailability of advanced SNG processes, and the need for crash programs. Let us not repeat this mistake. It is commonly held in energy planning circles that the major source of gyowth of U. S. energy supply will be from nuclear, and later solar, sources. The nuclear industry and many government planning groups seem to be committed to using these growing energy sources via the electrical route. As an example of this type of thinking, I would like to quote from a widely appearing advertise- ment from Westinghouse: `A worldwide electric economy is inevitable. There will be little alternative once all the world's natural fuels are exhausted. . We must make an immediate global commitment to an electric economy, one ultimately powered by nuclear energy. It is the only viable long-term solution to the world's energy problem." Hydrogen provides an alternative: The utility industry should be taking steps right now to adapt itself to delivering these energy resources to its con- ventional customers not only as electricity, but also as a combustible fuel gas, a form to which many of them are accustomed to using. This combination will serve their needs in the best way. Hydrogen can be made from a nuclear or solar energy heat source in two different ways. Using presently available technology we can produce electri- dty and use this to run an electrolyzer. The efficiency of turning heat to hydrogen this way is about 30% and could be increased to 50% through research. Such research is justified because it makes use of already developed electricity gen&ration technology. Alternatively, we can use the heat to drive a sequence of chemical reactions that produce hydrogen from water. Thermochemical processes, as these are called, are still in the laboratory stage, but research on both the chemistry and special type of nuclear reactor required is justified by the fact that such processes promise to have efficiencies greater than 50%. 34 PAGENO="0121" 115 ELECTROCHEMICAL HEAT * ELECTRICITY * ELECTROLYZER ~ HYDROGEN 30 ~ 50% THERMOCHEMICAL. HEAT ~ CHEMICAL PROCESS ~ HYDROGEN 50-55% Some encouraging developments are beginning to take place that suggest that attention is at last being given by government agencies to the production and use of hydrogen as an alternative carrier of nuclear energy. Among the most significant of these developments are - 1. A study was begun several months ago by AEC on how nuclear process heat can be used in iron and steel production, petroleum refining, coal gasification, and hydrogen production. They are using the services of General Electric, General Atomic, West- inghouse, the American Iron and Steel Institute, EXXON, Oak Ridge National Laboratory, and NASA to perform these studies. Input to this program from the utility industry has only recently been sought. 2. Technoeconomic studies and some laboratory research is in progress at Brookhaven National Laboratory on the use of hydrogen to store off-peak nuclear power. This work, supported by AEC, is directed toward the use of stored hydrogen to gen- erate peak load electricity, and is totally aimed at electric utility needs. - 3. NASA is formulating its plans for a major program on hydro- gen-energy applied to national energy needs (not just the use of hydrogen as an aircraft fuel). More than 3 million dollars are in next year's NASA budget for this purpose. While I am pleased that IGT has secured two NASA study contracts, I am disappointed that NASA's research plans have not in the past been well coordinated with those of the utility industry. From the point of view of continuing these new programs, I am very concerned when I read the published details of the recent restructuring of Government R&D under ERDA. Although the stated roles of ERDA include "policy planning of. . * research and development respecting all energy sources and utilization techniques " and `. . . conducting research in extraction, conversion, storage, transmission and utilization energy phases, " in the. original ERDA bill there was no mention of hydrogen. There seems to be no logical place for a comprehensive hydrogen-energy program under any of the six administrative divisions, which deal with fossil energy; nuclear energy; environment and safety; conservation; solar, geothermal and advanced conversion; and national security. However, PAGENO="0122" 116 the more recent National Energy Research and Development Policy Act, not yet signed into law, does include specific reference to hydrogen research, and the Senate version of the bill calls for demonstration of hydrogen as a fuel as a "mid-term' objective. While we might hope and expect that the existing AEC hydrogen projects are transferred intact into ERDA, there is no provision for the transfer or support of the new and significant NASA hydrogen programs, and no NASA representation is included in the President's proposed Energy Resources Council, which is charged to "insure coordination among the Federal agencies that have. responsibilities for the development and implementation of energy policy." I belive that Government research and planning efforts on hydrogen energy should be better cordinated than they are at present. The following actions are required: 1. The hydrogen-energy option should be examined as thoroughly as corresponding work; for example, on electricity transmission, battery storage, and electricity utilization. An appropriate re- sponsibility for the development of alternative energy delivery systems should be specifically assigned with ERDA's organization. 2. The hydrogen programs that have been initiated by AEC and by NASA should be protected during the formative stages of the new ERDA, and should be continued under ERDA's overall management. 3. Cooperative programs between the utility industry and govern- ment agencies must be developed in hydrogen-energy areas to insure that the long-range decisions being made by each are compatible with each other. 4. ERDA should collaborate with the nucleur industry and the gas industry to formulate a planned growth plan that will accommodate future gas and electric energy demands. It is important to recognize the long lead time (approaching 20 years) involved in implementing a substantial nuclear-hydrogen production industry. 5. ERDA should support a program of research and development on the special nuclear reactor engineering for high-temperature reactors of the type required for thermochemical hydrogen production. Neither the Conventional Pressurized Water Reactors nor the Liquid Metal Fast Breeder can provide high enough temperatures for this process. High_temperature reactor engineering is at present carried out under industrial, not government, sponsorship. In addition to the present Government hydrogen-energy program, industrial support of research on nuclear-hydrogen energy is also on the increase. General Atomic has a team working on thermochemical hydrogen production from its High Temperature Gas-Cooled Reactor, General Electric is research- ing both electrochemical and thermochemical hydrogen production, the 36 PAGENO="0123" 117 Electric Power Research Institute is investigating the use of off-peak power to produce hydrogen for use as a petrochemical feedstock and several electric utilities are carrying out transmission and storage studies, the most impressive of which,at Public Service Electric and Gas Company of New Jersey, has been described by Jack Casazza. Gas -industry supported hydrogen research at the present time includes a five-man level A. G. A. - supported program at IGT on thermochemical hydrogen production, a somewhat smaller industrially supported program, also at IGT, on hydrogen gas appliance development, and a rather larger effort at KMS Industries on hydrogen production by nuclear fusion re- actions. I believe that the utility industry's present level of involvement in this challenging new area is inadequate in view of the potential importance of this entire subject. What actions are needed by the utility industry today? First, companies which deal with natural gas need to take positive action to demonstrate to its investors that they have prospects for participating in a "perpetual" energy industry that is not subject to another resource depletion. Secondly, suppliers of natural gas must convince their customers that a supply of a gaseous fuel is reasonably assured for at least as long as the expected life of any new gas-using plant that they are about to install. Thirdly, the utility industry must demonstrate to ~g~y~rnment policymalēers that a nuclear-hydrogen energy delivery system is indeed a viable alternative to an all-electric economy; that the industry will be ready to operate such a system as soon as it becomes economically justified, and that in doing so, it will not be thrusting upon the public a new, untried or unwelcome form of fuel. Fourthly, the all-gas utilities must soon decide whether they will own their own nuclear plant, or will rely on the purchase of the product; and will this be electricity, heat or hydrogen? Some form of cooperation with the electric generating utilities seems inevitable since the latter have a 15-ZO year lead in the experience of constructing, owning, and operating such plants. Fifthly, the utility industry must soon persuade the nuclear indu~~y to pre- pare to increase the growth rate of nuclear capacity so as to be able to meet the energy needs of many new and existing ~ customers, as well as electricity customers, by the end of this c~ntury. To specify the number and types of nuclear plants required for hydrogen generation in the year ~u1O requires a considerable research effort now into hydrogen production technology. The utility industry cannot hope to make these impacts based on the meager level of study and research at present in effect. If the industry is to hope to demonstrate that hydrogen can be economically competitive with electricity, more research is needed to improve the efficiency and economy of both electro- lytic and thermochemical production. If it is to convince the public, its customers and the regulatory bodies that hydrogen is indeed a safe and viable all-purpose fuel, research must be extended to the transmission and especially to the distribution, utilization, and safety areas. 37 PAGENO="0124" 118 ROSENB~~ Our thanks to you, Derek, and to all of you; you may not have E~d time to answer all of the questions, but you have certainly supplied all of us with the basis for an effective action program. We still have a few minutes left before we conclude this morning's program. We at IGT are frequently asked a number of questions about hydrogen. I'm sure our audience would be interested in your answers to some of them. DISCUSSION ROSENBE~~ John Johnson has cited considerable industrial experience ~ the production, handling, and utilization of hydrogen in the space program. but this experience can't really be applied to domestic residences and apartment buildings. We don't have any experience in this area. Derek, people ask you this question quite frequently. Why don't you give us your answer. GREGORXi I usually answer that question (and, you're right, it is one that comes up very frequently) by saying that we do indeed have experience in that area. In the days of manufactured gas, we were putting a gas that was 50 percent hydrogen right into peoples' homes, and they were cooking and heating with it. In this country, we tend to forget those days a bit. But in Europe and Japan, many consumers are still using manufactured gas that is 50 percent hydrogen. The safety problems that we foresee for the use of pure hydrogen are almost as severe as those with 50 percent hydrogen. So, from the fact that we don't see housewives blowing themselves up every day with hydrogen in Europe and Japan and that they weren't blowing themselves up in this country 20 years ago, -I think we can make a good case that hydrogen can be handled safely. 38 PAGENO="0125" 119 ROSENBERG: John, you were talking before about the pipelining system and the fact that we do have experience in pipelining hydrogen. When we talk about converting to a hydrogen-electric economy, we are going to have to put that hydrogen in distribution system pipes that are now under the streets. Does Linde's experience in what we tend to term transmission pipelining have any bearing on natural gas distribution systems? JOHNSON: Yes, I think it does. The first concern is the belief held by some that such a system would leak profusely. Well, if you have a natural gas line that is leaking, you can bet that hydrogen will leak from it also. But I think that the fundamental principle is that you don't want a leaky line for either fuel, and, thus, you build a transmission pipeline so that it has no pores. That's the basic requirement. The second concern is that if you do have a leak, the volumetric flow of hydrogen from the line would be roughly 3 times that of methane. But, since the heating value of hydrogen is one-third that of methane, the energy flow is approximately similar so there is no extraordinary increase in the amount of energy seeping into the environment. The problem is that hydrogen tends to leak more readily; if it doesn't disperse, it then represents a hazard. That's basically the reason hydrogen has such a bad reputation. The basic rule with hydrogen is just don't let the leaks occur in the first place, and I am sure that's a rule of the gas industry, also. The third concern of many people is the embrittlement phenomenon. Generally, enibrittlement occurs only when pipeline pressures are about 2000 psi. However, since most hydrogen systems, particularly older ones, are nowhere near that pressure, I don't think this is a real concern. But again, it's an area where there is technology to draw upon. You can check your old designs to see if they conform with the codes and rules on how to beat the hydrogen embrittlement problem. Overall, the problems are not substantially greater in handling hydrogen than in handling methane. ROSENBERG: We apparently have some experience then with domestic applications and some revelant technology concerning distribution systems. One area where we have some very definite experience is with the problem of converting from one fuel gas to another. We had a conversion in this country a number of years ago when we converted from manufactured gas to natural gas. At that time, we had a lot fewer appliances. Now, when we look forward to conversion to a hydrogen economy, we are talking about a tremendous population of gas appliances. Is that going to make conversion prohibitively expensive? Jack, do you want to discuss this? CASAZZA: Yes, Bob. Frankly, I don't think we know. What we have so far is some good thinking and some experience, such as the work that Derek and John have mentioned. What we have to do is take a small sample area and start to get actual field data. I am a great believer in the need to get actual, observed experience under real-life conditions. Let's take a portion of one of our systems some day (I hope that it is in the near future); start blending some hydrogen in with the gas, perhaps even all the way to 100 percent hydrogen; and then make the necessary changes in the utilization apparatus. Let's get some good, hard data. Until we do that, we don't know if conversion is going to be prohibitively expensive or not. 39 PAGENO="0126" 120 ROSENBEB~ How can I disagree with that? That' s the way we learned so much in this industry, and it certainly has stood us in good stead. Let me turn from the hydrogen conversion problem to the production problem. We keep reading about the cost of nuclear reactors going up, the big delays, the cost of money, and electricity costs from nuclear reactors going up faster than those from fossil-fuel plants. Is this going to switch us from a nuclear- reactor-based electric economy to a fossil-fuel-based economy? Will it delay nuclear reactor construction or will it change some of the cost figures you gave in your prepared statement, Ken? The question is, will the cost of nuclear energy make hydrogen prohibitively expensive? JOHNSON: I think, as Jack indicated, that there are a couple of things that are happening now that are going counter to the kind of future that we have been talking about. With regard to the cost of nuclear power, I think you've got to distinguish between the capital costs of the plant and the fuel cost. It is true that the capital costs have been escalating, but the fuel cost has been rather stable, and, I would guess, it would be considerably more stable than fossil fuel cost for quite a while. Concerning capital costs, I think a major component of those costs is the interest during construction. As you get out into periods of 10 years required to license and build a nuclear power plant, this is indeed hurting the nuclear power industry. I think we have got to shorten the licensing lag time and the construction time to get the costs down so that nuclear power can play its proper role in the near term. We also have to overcome some of the public concern about reactor safety and get on with the job. ROSENBERG: Yes, this public concern is a key element. Jack, you've dealt with some of that concern firsthand. Is the public going to let us build the large number of nuclear reactors we need?- CASAZZA: Well, we think they are. As you know, we are working on this floating nuclear power plant concept. We believe that the public is getting closer to the point where they recognize how important nuclear power is to their overall quality of life. I think there have been some extremist people who have pointed up some of the potential hazards, while not letting the public know about the benefits. I think the fuel crisis that we have just been through and information on how much oil you can save by having one 1000- megawatt nuclear unit is the sort of information that is getting through to the public; I think they are beginning to evaluate both the pros and cons. While I can't say for sure, Bob, that siting and installation problems will be any easier, I think the trend is going in the right direction. If we can raise the capital, I believe we are going to be able to get the nuclear power plants in service that our society needs. ROSENBERG: Let me direct one last question to all of you. We frequently hear that hydrogen is a long-range solution to our energy problems - one way off in the future; that it's going to be important across the board in the U. S. economy and, therefore, the National Science Foundation or some equivalent governmental organization should be funding it; and that people like the gas industry do not have to be concerned with it now and shouldn't have to spend their own money on it at this time. Does anybody want to tell us why the gas industry should be concerned and why it should be funding research and development activities now? 40 PAGENO="0127" 121 CASAZZA: Maybe I can start, because, very simply, we think our future is at stake. I think that on your own you ought to look into things that determine your future. We do this in our personal lives, and I believe that in our corporate and industry thinking we ought to take the same approach. GREGORY: I think the really long-range research and the very expensive research is going to go into some of these new nuclear technologies and that research will have to be supported by the Federal Government. But unless industry sets the lead, indicates that it has the need, and is willing to participate and call the shots in the first place, I don't think the Government is going to be persuaded to put in the kind of money that is necessary. So, I think it's up to industry to take the lead - to sway the National Science Foundation, for example, toward long-term research in this direction. JOHNSON: I think that any research project can be evaluated in terms of its potential benefit, of how quickly it will be paid off, and of the risk that is associated with it. So it becomes a question of whether any individual company or institution or government can afford the risk after the benefit has been analyzed. I think the types of things that Jack is doing are clearly within the province of industrial institutions because the benefits are unique to their operations. He should be trying to find applications for the technology. Applications like the hydrogen-fueled airplane, where billions of dollars are involved, are clearly beyond the province of the airline and aircraft industries. Such financing probably will have to come from the Federal Government. So it's this kind of trade-off, where you ask if you can afford the risk, that determines who should fund the research. HOFFMAN: Well, I just would like to add a short note. I think it's evident that there are a number of near-term opportunities for increased efficiency and reduced cost in hydrogen energy systems and that such work is more appropriately done through the mechanism of industrial research. ROSENBERG: Gentlemen, before we bring this session to a conclusion, let me take a few minutes and try to summarize some of the points that you have been making. Ladies and Gentlemen, when you walked into this auditorium about 90 minutes ago, many of you were probably wondering what this hydrogen thing was all about. You were probably asking whether pipeline hydrogen in the nuclear era was one of those fine-sounding concepts that will have its day in the sun and then fade away, or, whether it is a real prospect for the future of the gas in- dustry. Now, 90 minutes later, I hope that the question in your mind has been both clarified and changed. I hope you're now asking yourself what your com- pany can do to help promote and to exploit the potential of pipeline hydrogen. The four presentations we heard this morning were all very pro-hydrogen. Wedid hear a brief interview with Dr. Edward Teller, who said that the hydro- gen economy was something for the future and may be unnecessary. There are some people who agree with him. But the speakers here this morning made a very strong case for the practicality of hydrogen. Jack Casazza even indicated that hydrogen had some very real near-term possibilities. He covered every- thing from using hydrogen in steel mills and in fertilizer plants to fuel cells and 41 PAGENO="0128" 122 the integration of a natural gas-hydrogen-electric system. And more import- antly, Jack cited actual tests now under way which could promote this near-term utilization of hydrogen. Jack Casazza is with a combination company and this gives him something of an advantage over a straight gas company. One of the problems each utility must face is how to make hydrogen when they decide they want it. Combination companies are experienced with nuclear reactors, but straight gas utilities have no operating background or experience. Here the comments of John Johnson are instructive. John pointed out that hydrogen may be produced from coal be- fore it is produced from nuclear energy. He said that Lurgi and the K/T pro- cesses are both prolific hydrogen producers and we're all aware that the develop- ment of these processes are the start of ourSNG industry. It's kind of funny when you realize that once the gas industry gets fully involved in commercial SNG operation, we'll be making more hydrogen than the world has ever seen, even more than Linde. Maybe you're convinced that your company can make hydrogen, but the question still remains whether you want it or not (or when you want it). Here Derek Gregory made a good point. He said that hydrogen could help convince both investors and utility customers that the industry and your company in particular is not dependent on natural gas supplies, or even on SNG, to stay in the gas business. If hydrogen really does that, it certainly has value for public relations and maybe it is even worth supporting some research. But consider those numbers that Ken Hoffman presented. Hydrogen sure looked good compared to electricity. It's not going to replace natural gas or SNG as long as reasonably priced supplies are available, but it is clear that special industrial applications are going to be attractive and maybe soon. Possibly your company can get in on the growing market for commodity hydrogen. OK, this presentation was all pro-hydrogen, but it made a pretty good case for your company getting interested. It's inevitable that we'll encounter a lot of problems as we try to develop the pipeline hydrogen concept. That's why every one of the speakers made recommendations for immediate action. Each of them said that we need to improve efficiency in hydrogen production and lower costs, improve equipment and increase reliability. These are industry- wide problems which should be handled on .a collective basis. But some of those other recommendations were interesting because they relate to how your company can get involved. What were they? Cost benefit analyses to see just where and how soon hydrogen can be used by your company, specifically: 1. Public information and education programs to help formulate positive policies and attitudes. Z. Investor and customer seminars to establish our credibility as a long-term component of the energy industry. 3. Improved safety and hydrogen system demonstrations. . everyone stressed the need for these. They certainly will affect the attitudes of both the public and the decision makers. 42 PAGENO="0129" 123 4. Support of industry-wide research to advance necessary hydrogen developments. And, 5. More cooperative efforts with Government, the nuclear industry, and others to establish our needs and priorities. The long-range plans now being made must have our in- puts so that pipeline hydrogen can plan its rightful role in the nuclear era. We hope that you have found this an enlightening morning and that you agree that this hydrogen idea may prove very useful. We also hope that when you receive your copy of this seminar in the mail, you'll circulate it and initiate the steps necessary to develop an action plan for your company. Ladies and Gentlemen, if this is the conclusion and the resolve yo&ve reached from this morning's presentation, we are gratified. Thank you for coming. FILM REPRISE VO: We have recognized hydrogen as a plentiful, clean-burning fuel that can be handled safely in large quantities. Looking ahead we see hydrogen as a fuel that is economical to transport and store. A fuel that can be readily and economically substituted for fossil fuels. A fuel that a growing number of energy experts favor for the transition into a nuclear-based economy. (MONTAGE OF PORTIONS OF INTERVIEWS WITH LUXO, CLARK, ORDIN, and BAIN) We have offered evidence that substantial technology already exists. And we know the present gas industry will obviously play a more important role in storing and handling nuclear heat as hydrogen than if the all-electric alternative is selective. The research and development lead time required for major new technology has been dramatically illustrated in the present efforts to develop synthetic fossil fuels technology. We must begin at once if we are to accomplish the formidable task of developing the nuclear-based hydrogen technology by the next century. That's just 26 years away. 43 62-332 0 - 76 - 9 PAGENO="0130" 124 WORLDWIDE RESEARCH ACTIVITIES IN HYDROGEN ENERGY December 12, 1974 by D. P. Gregory Institute of Gas Technology Chicago, Illinois 60616 Introduction The concept of using hydrogen as an energy carrier and universal fuel is attracting a great deal of interest worldwide. Many studies and experi- mental projects are currently under way either evaluating the prospects for or preparing to participate in some sector of the hydrogen economy. This interest in hydrogen has grown significantly in the last 2 years and has obviously been stimulated by the realization of a worldwide fossil fuel shortage. Significant hydrogen-energy research began in the United States and in thE EURATOM laboratory in Italy 4 or 5 years ago, but has now developed to include work in Canada, Brazil, Australia, Japan, West Germany, France, and England. Early work concentrated on the concept of the "hydrogen economy," an energy economy in which hydrogen produced from nuclear or solar energy is used as a i~niversal fuel Loralmost every energy application. However, many of the ~fforts now under way are aimed at one or more of the rather smaller segments of this `economy" - to produce and utilize hydrogen as an energy form for some specialized application and to compare it with other unconventional energy systems. We at the Institute of Gas Technology believe that many of these specialized appli- cations are of direct interest to the gas industry and that their exploitation could grow into a mixed energy-supply system in which the customer load is shared by hydrogen, electricity, and other nonfossil energy forms. Considerable emphasis is being placed on relatively short-term appli- cations of hydrogen derived from fossil fuels, such as coal, to supplement or replace some conventional energy or feedstock systems. Hydrogen may be produced from coal or oil shale at efficiencies ard costs similar to those involved in the production of SNG. For certain applications, hydrogen is PAGENO="0131" 125 superior to SNG. Thus, several companies are investigating the alterna- tive of making hydrogen directly and pipelining it to the specialized user instead of making SNG and subsequently having the consumer turn it into hydrogen -for example, in an ammonia plant or steelworks. Just as is true for SNG, technology is available today for producing hydrogen from coal, but more economical and efficient processes can be developed in the future. Hydrogen may also be produced by electrolysis using electric power. This route offers a way of using known technology and existing electric generator equipment. However, an electrolytic hydrogen plant fueled by a fossil fuel has little merit since hydrogen could be made chemically from the fossil fuel both more efficiently and more cheaply. Nonetheless, many recognize electrolysis as a short-term available option to make hydrogen from off-peak fossil-fuel-based electric power and from off-peak or base-load nuclear power. Since the load factor on a generating plant in the United States is about 55%, a great deal of generating capacity is potentially avail~. able. As nuclear capacity grows, the electric utilities predict an increasing availability of off-peak nuclear capacity, for which profitable off-peak uses should be found. Uses involving hydrogen that are being investigated include storing it for sub seqoent electricity generation and using it to supplement industrial hydrogen conventionally made from fossil fuels. We believe that the second of these options has the most merit. Electrolysis technology is available today, but like SNG processes, improvements in efficiency and economics are expected to be developed In the future. A third hydrogen production method, and one that is receiving the most research support today, is the thermochemical splitting of water, using a heat source, without an electrical intermediate. Heat is used to drive a number of chemical steps in a cyclic sequence, all the components of the cycles, except water, hydrogen, and oxygen, being recycled. No commercial technology is available for this process today, but several research groups are conducting experimental trials of chemical reactions, and even more have carried out detailed thermodynamic analyses of the theoretical efficiencies of various cycles. Much of this work is held pro- prietary by the researchers. IGT has identified some 70 theoretically possible cycles, several of which possess calculated, and possibly attain- able, heat-to-hydrogen efficiencies greater than 50%. In contrast, nuclear heat-to-electricity efficiencies are at present only about 35% and are only PAGENO="0132" 126 expected to rise above 45% in the future with some difficulty. Electrolyzer systems should be capable of delivering beat-to-hydrogen efficiencies in the same 35-45% range. IGT believes that EURATOM and IGT are the only two research teams in the field who have actually "demonstrated' all the steps of an efficient (above 40%) cycle in which all the chemical reactants have been physically recycled and all the product separations have been made. One of IGT's chief concerns about the commercial application of thermo- chemical hydrogen production is the need fo~ a special type of nuclear reactor capable of delivering high-temperature heat. Such a reactor, needed to produce the high efficiencies discussed earlier, would require several years of special- ized development in nuclear engineering. Although such development is already going on, for example, at General Atomic Company, San Diego, California, and at Kernforschungsafllage (KFA), JUlich, West Germany, we recognize that the lead times required to develop a substa~itial business to produce thermochem- ical hydrogen are very long-about 20 years or more. Because hydrogen can be made from a wide variety of energy sources, it is being considered as a transitional fuel to span the time when the U. S. energy supply is changing from fossil to nonlossil energy sources. Begin- thng with hydrogen made from oil and gas through hydrogen from coal, oil shale, and nuclear power, longer term programs aimed at harnessing solar, wind, and tidal energy in the form of hydrogen are already in the conceptual research stage, supported by the National Science Foundation (NSF) and its foreign equivalents. Worldwide, research efforts on hydrogen energy topics range from a few small teams of a dozen or so people to many individual efforts in university laboratories. The efforts are uncoordinated and dispersed, both in the nature of the work and in the objectives. To present a picture of worldwide hydrogen efforts, we have classified them by application objec- tives in the following end-use categories:* * Feedatock for ammonia and methanol * Upgrading of oil, coal, and oil shale * Iron and steel production * Energy storage * Unique single applications of hydrogen such as in NASA's space efforts are not included. 3 PAGENO="0133" 127 * Supplement to natural gas and SNG * Transportation fuel * Replacement for natural gas. The objectives of the work and a listing of some of the organizations support- ing research are given in Appendix A. We think hydrogen derived first from coal, and later from nonfossil energy, will reach significant usage in these applications iii the order given. Use of hydrogen in each category will have significant impacts on the gas industry. Classification in this way makes the present hydrogen effort look more organized than it really is. Many activities are really mo~e loosely directed and cannot be accurately classififed, while others are applicable to more than one end-use objective. It is difficult to draw up an all-inclusive listing of hydrogen research or to assign dollar values to all of the research efforts. In some cases, the magnitude of the effort simply is not recorded. In others, funding of- ficially assigned for one fiscal year iti actually being spent in another. In Appendix B we have attempted to provide a comprehensive listing of world- wide hydrogen projects that we know about and have also attempted to assign a U. S. dollar value corresponding to our best estimate of the present level of activity. About 40 separate projects are at present being supported by six different U. S. Government agencies, about 15 U. S. companies are carrying out hydrogen-energy research with their own funds, and hydrogen programs are being conducted in at least 10 countries outside the United States. We estimate that about $10 million/yr is being spent worldwide on hydrogen research today. Some Industrial and Government Opinions About Hydrogen as an Energy Medium In the United States, the Atomic Energy Commission (AEC) and the majority of the "nuclear industry" have, for a long time, taken the attitude that a nuclear-energy economy is synonymous with an all-electric economy. This opinion is being voiced strongly by Westinghouse Electric Corporation in a series of widely appearing advertisements (although this view is not held by many senior research staff members at Westinghouse). Recently alternative applications of nuclear reactor heat have gained increasing attention for such purposes as steelmaking, coal gasification, oil-refining, and synthetic 4 PAGENO="0134" 128 fuel production. The use of heat to generate hydrogen from water is a key step in all of these applications. The principal U. S. proponent of this approach is General Atomic, but in Europe, EURATOM, the German Center for Nuclear Research, and the U. K. Atomic Energy Authority (UKAEA) have had a longer and harder look at the concept. All of these organizations have access to high-temperature nuclear reactor technology, and all except the UKAEA have active research programs on thermochemical hydrogen production. The USAEC recently funded studies in all of these applications of nuclear heat and formed a coordinating committee to monitor their progress. IGT and A. G.A. were invited to serve on this committee, but were barred from the first meeting because of legal formalities within the AEC. Companies such as General Elec- tric, General Atomic, and Westinghouse were admitted because they have AEC contracts. Many electric and combination utilities view hydrogen energy with en- thusiasm. Hydrogen can serve as a storage medium and as a form of in- expensive underground transmission, and integrates well with their proposed use of the fuel cell as a two-way link between their gas and electric systems. Many U.S. electric and combination utilities are supporting their own hydrogen research efforts, in addition to work supported by the Electric Power Research Institute (EPRI). We note with interest the studies performed by a number of electric utilities that look very positively at the potential of hydrogen to serve as a relatively inexpensive medium for underground energy transmission. These studies are carried out mainly by the utilities serving the highly urbanized areas of the Northeast and southern California, where further overhead- line construction is being discouraged. The attitude of some of the all- electric companies carrying out this research is that an all-electric economy is more expensive and less efficient than a mixed hydrogen'.electriC energy system, and that the electric utilities themselves would be in the best position to make nuclear hydrogen and sell it to the gas industry, which would merely have to deliver it to its gas customers. Several gas utility companies view hydrogen as a long-term solution to their supply problem, but are hesitant to support research directly, f~1ng that such research should be A. G. A. `s responsibility. At least two notable exceptions to this are Texas Gas Transmission Corporation, which has its own research effort in hydrogen productiorb and Southern California Gas Com- pany. which has a ventless appliance program that is directly relevant to hydrogen utilization. 5 PAGENO="0135" 129 Gaz de France sees hydrogen energy as a necessary adjunct to the wide- spread introduction of nuclear energy in France. In a cooperative program with Electricit( de France, it visualizes a mixed hydrogen-electric delivery system as being essential. British Gas seems to be complacent about its North Sea gas reserves and has no active program on hydrogen. Some German companies, such as Ruhrgas, believe that hydrogen transmission is not appropriate for their short transmission distances. The Japanese have shown an extraordinary interest in U. S. hydrogen programs and are now beginning their own research efforts; the Ministry of International Trade and Industry has included a $1 million/yr effort on hydrogen as part of the Sunshine Project. The aircraft industry has long been enthusiastic about the light weight of hydrogen fuel. The possible use of hydrogen for subsonic passenger aircraft is viewed enthusiastically by NASA and Lockheed, which have re- search efforts in progress, but with some alarm by TWA and Pan-Am because of equipment cost and public acceptance. This subject has been extensively discussed by a National Academy of Engineering Committee on Alternate Aircraft Fuels. The U. S. atomohile industry is not openly active in hydrogen research, although many small independent projects are concerned with nonpolluting engines operating on hydrogen. In contrast, Daimler-Benz and Volkswagen both have some form of hydrogen-energy projects under way. Among U. S. Government agencies, NASA, which has identified itself as the "lead agency" for hydrogen research, is currently funding about $ 1. 5 million of hydrogen-energy effort, has $3 million or more earmarked for fiscal year 1976, and is enthusiastic about all aspects of hydrogen use. Most of the AEC-controlled national laboratories have hydrogen research projects, but these projects are not centrally coordinated. The AEC is cur- rently spending about $2. 0 million/yr on hydrogen. The Advanced Research Projects Agency of the Defense Department is studying hydrogen as an all- purpose military fuel for both vehicle and static applications; current spending is at the rate of about $400, 000/yr. The Environmental Protection Agency sees hydrogen as an ultrac lean vehicle fuel and is spending about $400, 000/yr on methods of storing it or producing it on-board a vehicle. All of this government work is uncoordinated; even within each agency, nobody seems to have a clear picture of exactly what is going on in hydorgen research. PAGENO="0136" 130 It appears that the Energy Research & Development Administration (ERDA) will have hydrogen research in its proposed program. It will automatically take over the AEC axxl EPA work, but not the NASA and DOD projects. Some guidance from the gas industry seems to be called for in this formative period for ERDA research policies. Gas Industry Opportunities The gas industry has a number of opportunities in hydrogen, which may be summarized as follows: * The gas industry does not have to wait for the year 2000 before entering the hydrogen business. It can develop new and growing markets by making and delivering hydrogen to the petrochemical, oil-refining, iron and steel, and aviation industries. Such new markets could be developed in the 1980 to 2000 time frame, using coal as the source of hydrogen and providing a sound basis for the transition toward nonfossil hydrogen sources in the longer range. * The gas industry can develop the technological know-how to produce hydrogen from nuclear energy and from solar energy. Research along these lines is very long term and probably has a 25-year or more payoff time. For example, estimates of the time re- quired to pursue thermochemical hydrogen production through all the logical steps including bench test, pilot plant, and demon- stration plant indicate that benc~i-sca1e research is needed now if plants are to be in commercial operation soon after the year 2000. The gas industry should regard this type of activity as "life insurance." * The gas industry can influence national energy planning to include the option of using its existing transmission and distribution facilities to deliver hydrogen energy when the need arises. To do this, the industry must demonstrate that these facilities are compatible with hydrogen or can be easily modified to operate with it. * The gas industry can gain the confidence of the public so that it will. accept hydrogen as a clean and safe fuel. Public opposition to nuclear power, to electric transmission lines, and to mining operations has already done much harm to the utility industry. The clean nature of hydrogen combustion and its lack of an unsightly delivery system can be used to attract public support. .7 PAGENO="0137" 131 * All of the components of a demonstration hydrogen-energy system, from electrolytic production to pipelines and combustion equipment, are already available. While future research should be aimed at improving the economics, efficiency, and safety of these compo- nents, a short-term demonstration using the present state-of- the -art could be beneficial. A large ERDA program could involve the construction of a pilot-scale field test and the demonstration of a hydrogen-energy system. The gas industry has the oppor- tunity to collaborate or lead in this demonstration activity, which can do much to project the image of an industry with a long-term* supply availability. * The gas industry can play a cooperative role -with the electric industry in producing hydrogen from off-peak electric power and in pipelining it for use in such applications as fuel cell generatore and petrochemical plants. As an alternative, the possibility of mixing this hydrogen with natural gas up to a point* that still has no effect on the utilization equipment could provide an appreciable supplement to supplies in the very short term. This off-peak storage activity, which could be developed in the 1985-2000 time frame, will also open up new marketing opportunities for by-product oxygen and heavy water. * The gas industry could use its expertise in underground gas storage to provide seasonal storage capability to the nuclear- and solar- electric utility industry. Such storage capacity will be needed be- ginning in about 1990. ~gq~ired Thrust of a Gas Industry R&D Program on Hydrogen 1. Long-term research in thermochemical hydrogen production is justified becauBe of the potentially lower cost and higher efficiency of the process. Close liaison with the high-temperaturenuclear reactor industry is needed from now on, as both are carrying out experimental programs in chemistry of new processes and the chemical engineering of plant designs. 2. Because of the recognized materials problems in thermochemical hydrogen production and because of the dependence of thermo- chemical hydrogen production on a special type of nuclear reactor, an alternative means of producing hydrogen should also be developed. Improvement of the present electrolyzer technology is thus justified because electrolyzers would have the near-term potential of playing a major role in the use of off-peak electric power to supply a number of gas industry customers. 3. Close liaison and cooperation with the nuclear part of ERDA (the old AEC), the nuclear industry, and the Electric Power Research Institute appear necessary if we are to ensure that the planned * Perhaps 30% as indicated by some IGT work. 8 PAGENO="0138" 132 growth rate of nuclear plant capacity is not completely dominated by the needs of the electrical industry without consideration of possible gas industry needs. 4. Short-term emphasis should be placed on the development of eco- nomical and efficient means of producing, storing, and delivering hydrogen made from coal and oil shale to the petroleum-refining, petrochemical, iron and steel, aviation, and ground transportation industries. The gas industry's need for and capability of supplying itseLf with the vast quantities of hydrogen needed for SNG production should be closely integrated with this field of operation. 5. The capability of the gas industry to play a major role in delivering tomorrow's nuclear and solar energy in its existing equipment must soon be proved and demonstrated so that long-range commit- ments can be made. To do this, urgent attention should be applied to the materials, safety, and design problems of operating present transmission and distribution equipment on hydrogen. 9 PAGENO="0139" 133 APPENDIX A. Objectives in the Application of Hydrogen Research The Growing Importance of Hydrogen Hydrogen is used today as a chemical feedstock, as a metallurgical reducing agent, in food processing, and in many other applications. It is currently used only to a small extent as a fuel gas. We can identify a grow- ing role for hydrogen in all of these applications, which would provide a good basis for the growth of a hydrogen-production business. Almost all hydrogen produced today comes from natural-gas- or naphtha-reforming. Since both of these feedstocks are in short supply, a growing demand for hydrogen can best be met by the development of processes that make hydrogen from a) coal, b) oil shale, and c) nuclear or solar energy sources. These processes would be applied to the production of hydrogen in the indicated order. Hydrogen will grow in importance in the following applications: 1. As a chemical feedstock (ammonia and methanol) 2. For upgrading oil, coal, and oil shale to useful fuels 3. As a reductant in the production and manufacture of iron and steel 4. As an energy-storage medium 5. As a fuel to supplement the supplies of natural gas and SNG 6. As a fuel for transportation 7. As an ultimate replacement for natural gas. Hydrogen is already used in the first three categories. It will come into use in the other categories and its use in all of these applications will increase, in the order given. ~jydrogen in Chemical Manufacture The major uses of hydrogen today are for the production of ammonia and methanol, and in petroleum-refining. Ammonia and methanol production in the United States currently consumes about 1. 2 trillion SCF/yr of hydrogen. Most of this feedstock hydrogen is produced onsite from natural gas. Natural gas supplies are unable to keep up with the growing demand for ammonia, and the cost of ammonia is very sensitive to increasing natural 11 PAGENO="0140" 134 gas prices. Ammonia is the basic raw material for fertilizers; methanol is a precursor to many industrial solvents and plastics. Alternative sources of hydrogen include production from a central coal gasification plant, from off-peak electric power by electrolysis, and from dedicated nuclear-thermochemical plants. Economics of scale suggest that one central coal or nuclear plant should provide the most economical service to a number of conventionally sized ammonia or methanol plants. `If off-peak hydrogen supplies are used, they must be gathered from a num- ber of power stations, stored, and pipelined to the industrial users. Some substitutions of hydrogen produced from these alternative sources for natural gas could be justified now. The application of pipelined hydrogen to chemical manufacturing could begin by 1980. Work is under way on the following areas that are relevant to this application: production of hydrogen by electrolysis, coal gasification, and nuclear water-splitting; pipelining; and storage. Organizations carrying out this work include EPRI and some industrial pipeline companies. Hydrogen in Fuels Production One of the major uses of hydrogen today is in petroleum-refining, where it is used to upgrade heavy oils to lighter fractions such as gasoline and jet fuel. Some 800 billion SCF/yr of hydrogen are used for this purpose. In producing synthetic fuel from coal or oil shale, hydrogen fulfills the same "upgrading" function. A single 250 million SCF/day HYGAS plant would produce and consume about 100 billion SCF /yr of hydrogen (about one-tenth of the total U.S. use for ammonia). Thus, the gas industry is likely to become the world's largest user of hydrogen. The present sources of hydrogen for petroleum-refining and SNG pro- duction are from oil or gas in the refinery, or from coal or oil shale in the SNG plant. Alternative sources of hydrogen include a central coal- gasification (hydrogen-producing) plant to supply refineries by pipeline and a central nuclear water-splitting plant to supply refineries and synthe- tic fuel plants. Adoption of such a scheme would reduce the consumption of oil and coal in the manufacture of conventional and synthetic fuels. 12 PAGENO="0141" 135 Economics of scale, especially for the nuclear case, suggest that a central production plant serving several customers by pipeline would be preferred. Introduction of hydrogen from coal to oil-refining processes could be justified now and could enter service in 1980 to 1985. Introduction of hydrogen derived from electrolysis using nuclear energy and later from thermo- chemical processes to both oil-refining and synthetic fuel production may be possible in the 1990-2000 period. Work is under way in the following areas that are relevant to the use of hydrogen to produce synthetic fuels: coal-to-hydrogen processes, nuclear water-splitting, and pipelining. Organizations that are working with this objective include AEC (ERDA), Oak Ridge National Laboratory, EURATOM, the German Government, General Atomic, and General Electric. Hydrogen in Iron and Steelmaking In the iron and steel industry, coal is currently used partly to supply a heating fuel, but primarily to provide a chemical reducing agent. Large volumes of atmosphere gases for annealing and heat-treating operations are made from natural gas and naphtha. Concerns over rising coal prices, environmental protection requirements, and gas curtailnients are causing the iron and steel industry to look for other energy sources. Hydrogen can meet the reducing-agent, fuel-gas, and atmosphere-gas needs with known technology. Already, some direct iron ore reduction plants are operating on hydrogen (produced from natural gas). Hydrogen produced from a central coal-gasification plant, serving several mills by pipeline, is an attractive alternative to the present system. Hydrogen produced from water by nuclear energy is also under serious consideration as a longer term project. Work is under way on the following areas that are relevant to this application: nuclear water - splitting, nuclear-assisted fossil-fuel-reforming, and direct hydrogen reduction of ores; Organizations that have programs involving the use of hydrogen in iron and steelmaking include the AEC, the American Iron and Steel Institute, Atomic Energy of Canada Ltd., and the Steel Company of Canada, Ltd. 13 PAGENO="0142" 136 ~y~rogen as an Energy-Storage Medium A major need of the electricity transmission system is storage capability. Significantly funded research programs on compressed-air storage, hydraulic storage, batteries, flywheels, and hydrogen-storage systems are currently in progress. The need for the storage of electrical energy becomes more severe as - 1. Increasing nuclear capacity is installed; nuclear plants perform best at a constant output.. 2. Electric energy takes over an increasingly growing share of the various areas of the traditional fossil fuel market, such as space heating, with its large seasonal peaks. 3. Transmission systems become overloaded during peak periods. 4. Solar, wind, and tidal energy sources become seriously considered. The hydrogen-storage concept for electrical utilities has several forms; all rely on the use of electrolysis to produce hydrogen during periods of low demand. One option is to provide the necessary "spinning reserve" of power generation by a plant that normally produces electrolytic hydrogen on an in- terruptible basis. The hydrogen could be stored within the pipelines~ in underground fields, in pressure vessels, as liquid hydrogen, and as chemical hydrides. Recovery of the energy can be by - * Using central or decentralized fuel cells or hydrogen turbine generators * Mixing hydrogen directly with an existing natural gas supply * Supplying hydrogen to major petrochemical and industrial hydrogen users. The need for large utilization of off-peak electrical capacity is immi- nent. The present load factor of all U. S. electrical generation plants is 55%. Application of hydrogen in this area could begin between 1980 and 1985. Work is under way in the following areas that are relevant to the use of hydrogen as an energy-storage medium: electrolysis, hydride storage, pres- sure vessel storage, pipelining, fuel cell generation, hydrogen turbines, and Integration with the gas and petrochemical industry. Organizations that have programs involving this application include the AEC; Brookhaven National Labora- tory; Allied Chemical Corporation; Isotopes, Inc. (a subsidiary of Teledyne, Inc.); 14 PAGENO="0143" 137 General Electric Company; United Aircraft Corporation; Rocketdyne; and several elecrric and combination utilities including Public Service Electric and Gas Company of New Jersey, Niagara Mohawk Power Corporation, and Northeast Utilities. Solar, wind, and thermal power systems studies incor- porating hydrogen storage are being studied by the National Science Foundation; TRW, Inc.; and Global Marine, Inc. Hydrogen as a Supplement to Natural Gas and SNG Energy demand and supply projections indicate a continually increasing shortfall in the supply of natural gas. By the 1980's, our natural gas supply will be enhanced by coal-based SNG as well as by imports of L]~G from foreign sources. However, these new supplies will not be adequate to satiźfy the deficit between demand for gaseous fuel and the supply. Hydrogen from nuclear power could further supplement this natural gas-SNG supply. Nuclear-based hydrogen, using water electrolysis, is a particularly attractive technology for the 1980's because it would not be in competition with other fuel-synthesis processes for mined coal and because nuclear electrolysis plants could be sited in water-plentiful areas. Furthermore, off -peak nuclear power available to mixed electricity and gas utility systems could be used for hydrogen production until such time as base-load hydrogen systems are developed. Today several utility companies are evaluating supplementing their pipeline gas supplies with hydrogen produced by electrolysis using off-peak power. Among these are Niagara Mohawk Power Corporation and Public Service Electric and Gas Company. The amounts of hydrogen that could be used depend upon the off-peak generating capacity, the current statutor\y limits for the heating value of delivered gas, and, ultimately, the maximum amount of hydrogen that is compatible with utilization equipment. This latest value might be as much as 30% hydrogen. Hydrogen as a Transportation Fuel Hydrogen is attractive as a fuel for transportation uses because - * It is virtually nonpolluting. * It has desirable ignition and combustion characteristics. 15 PAGENO="0144" 138 * It is lightweight compared with aircraft fuels on an equal-energy basis. * It is potentially available in large quantities from domestic coal and nuclear resources. Both piston engines and gas turbines have been converted to operate satis- factorily on hydrogen. The primary problems are associated with the storage of hydrogen on-board the vehicle, the design of distribution and vehicle filling stations, and public safety. Because of its light weight, hydrogen has great technical advantages when considered for use as an aircraft fuel. Handling problems for ground vehicles are minimized when vehicles that refuel at specific locations, such as buses, trucks, and trains, are considered. This type of application of hydrogen could begin in 1995. Aircraft operation on hydrogen could also begin inthe 1990's. Work is under way in the following areas that are relevant to the use of hydrogen as a transportation fuel: hydrogen production from coal, im- proved hydrogen liquefaction techniques, hydrogen aircraft design, gas turbines, hydrogen piston engines, automobile fuel tanks, hydride systems, and-technology assessments. Organizations that have programs involving this application include NASA, Linde, lOT, Lockheed, Boeing, United Air.- craft, the EPA, Jet Propulsion Laboratory (JPL), Billings Energy Research, Cornell University, Beech Aircraft, Brookhaven National Laboratory, Allied Chemical, the University of Denver, and Stanford Research Institute. Hydrogen as an Ultimate Replacement for Natural Gas Hydrogen, made from nuclear or solar energy, is the simplest nonfossil synthetic fuel that could be used as an alternative to electricity. Many govern- ment and industrial advocates of nuclear and solar energy regard the "all- electric economy" as the only way to use these nonfossil energy sources. - Hydrogen has several advantages over electricity in that it is cheaper to transmit, is storable, is potentially more efficient to produce, and can be used by present equipment with a minimum of replacement. The justification of the hydrogen-energy alternative depends upon the ability to produce suffi- cient quantities of hydrogen; to deliver it, primarily in existing transmission and distribution systems, at a price competitive with electric power; and to use it safely in all current applications met by natural gas. 16 PAGENO="0145" 139 Complete conversion of natural gas systems to hydrogen systems will probably not be justified until after the year 2000. The decision to convert is dependent on both a) the capacity for, and the cost of, producing hydrogen and b) the cost of delivering it to the customer. The decision must wait un- til there is an economic incentive for the consumer to switch from using a conventional fuel to using hydrogen rather than to electricity. New residential developments, unable to obtain gas supplies, possibly could be the first in- stances of an economically justified hydrogen-energy supply. Research on hydrogen production, hydrogen-energy systems, and hydrogen- utilization equipment with the objective of using hydrogen as an ultimate re- placement for natural gas is in progress at A. G.A., IGT, Gaz de France, ETJRATOM, the Institute for Systems Analysis, General Electric Company, the Department of Defense (ARPA), Texas Gas Transmission Corporation, and KMS Fusion, Inc. 17 62-332 0 - 76 - 10 PAGENO="0146" 140 APPENDIX B. Comprehensive Listing of Worldwide Hydrogen Projects Completed or Now in Progress Even though this list is an attempt to ir~clude all projects that we know about, there is no official catalog or reference source on hydrogen research, even for the research supported by the; U. S. Government, so this list is almost certainly incomplete. Dollar values are IGT's estimates of the present levels of activity, where known. Projects are classified into three categories ac- cording to the level of information available: A. Programs well known to IGT by direct contact with researchers B. Programs that IGT knows to be in existence through indirect contact C. Programs that are known to IGT only by the existence of a research paper in the literature. SGIJM 19 PAGENO="0147" Table 1. HYDROGENRESEARCHATIGT ________ Descriptive_Title __________ Research Programs Analysis of the "Hydrogen Economy' Concept 1971 The rmochemical Hydrogen 1972-7S Production (Currently Active) Optimization Calculations for Hydrogen Transmission Pipeline 1973 Analysis of Hydrogen Embrit- tlement of Pipeline Steels 1973 Survey of Hydrogen Research Outside the Gas Industry 1973 II. Government Research Prog rams (Excluding Gasification) U.S. Navy Assessment of Electrolyzer (Stevens Institute Technology 1974 $ 9,000 Subcontract) EPA Assessment of Alternative Vehicle Fuels (including hydrogen) 1974 $133,000 Study of Automotive Storage 1974 of Hydrogen (Currently Active) ,$ 37, 000* Hydrogen-Fueled Appliance Testing 1974 -~ Economics of Coal Conver- 1974-75 sion to Hydrogen, Methane. and Kerosene for Aircraft (Currently Active)~ 74, 000* NASA Survey of Hydrogen Produc- 1974-75 tion and Utilization Methods (Currently Active)$169~ 000* III. Industry Research Programs (Excluding Fuel Cell Development~ MAPCO, Inc. Evaluation of Technology for Pure Hydrogen Production 1973-74 - - From Coal Pratt & Whitney Hydrogen From Oil for Fuel Aircraft Cells Southern Calif. Appliances to Use Hydrogen or Gas Co. Hydrogen-Rich Fuels Daimler-Benz Study of Problems in Hydrogen-Fueled Vehicles Electric Power Economics of Hydrogen for Research Institute Commodity Sale Fro,m Off- _________ Peak Power * Amount funded for project including cost to date. A-114-21Z7 141 Year(s) Total Active Cost Sponsor I. A.G.A. A.G.A. A.G.A. A. G. A. A. G. A. A. GA. EPA EPA (Engelhard Subcontract) NASA 1973-74 -- 1972-74 -- 1974-75 -- (Currently Active) 1974-75 -- (Currently Active) $233, 000 21 PAGENO="0148" Table 2. PROGRAMS SPONSORED BY NASA Coordination of all NASA - sponsored work on hydrogen energy Planning of NASA hydrogen-energy research program RFP issued for 6-month study to investigate hydrogen production using high-temperature nuclear reactors, September 1974 Theoretical evaluation of thermo- chemical water-splitting Feasibility and design studies of a hydrogen-fueled subsonic aircraft Comparison of cost and efficiency of making hydrogen and other synthetic fuels from coal Systems studies on niaking hydrogen from coal and liquefying it for use as an aircraft fuel Survey of hydrogen production and utIlizatIon methods NASA-Ames and Lockheed Design of a hydrogen-fueled super- sonic aircraft NASA-Ames and Electrolyzer development Life -Systems U.S. Dept of Commerce, Hydrogen safety survey National Bureau of Stan- dards NASA-KSC and Bendix NASA - Lewis Conversion of vehicles to use hydrogen Emissions from engines running with hydrogen injection Univ. of N. M. Bibliography and literature search on hydrogen A nnual Funding, $1000 Category 100 A 300 A 150 B Contractor Investigation In-house Jet Propulsion Lab NASA - Lewis NASA-Lewis and Univ. of Kentucky NASA-Langley and Lockheed NASA-Langley and lOT NASA-Langley and Linde NASA-Marshall and lOT 35 A 3S0 -- 75 A 34 B 170 A 100 B -- B 110 B -- B -- A -- A A-I 14-2 135 PAGENO="0149" Table 3. PROGRAMS SPONSORED BY THE AEC Annual Contractor Investigation Funding, $1000 Category AEC -Headquarters Coordination of studies on use of high-temperature process heat B NASA-Lewis Thermochemical hydrogen pro- duction B Oak Ridge Nati. Lab Thermochemical hydrogen pro- duction - experimental study B Los Alamos Thermochemical hydrogen pro- duction - experimental study Total about B ~ Argonne Nati. Lab Thermochemical hydrogenpro- 500 duction - experimental study B Lawrence Livermore Thermochemical hydrogen pro - duction -experimental study B Brookhaven Nati. Lab Basic hydride storage research B Brookhaven NatL Lab Development of system for elec~ trolysis, hydride storage, and 800 A fuel cell conversion for off-peak storage Los Alamos Field trials of liquid-hydrogen- fueled truck B Iowa State Univ. Thermochemical hydrogen and basic hydride research B PAGENO="0150" IGT Exxon Engeihard Industries, Inc. Brookhaven Natl. Lab IntHarvester (Solar Div) Argonne Nati. Lab Inve stikation Generation of hydrogen from gaso- line on-board vehicle, and studies of engines running with hydrogen injection Generation of hydrogen on-board* automobile Generation o.f hydrogen on-board automobile Development of catalytic burners for hydrogen appliances Lightweight metal hydride storage Metal hydride research Motor vehicle storage or hydrogen using metal hydrides Contractor Jet Propulsion Lab Table 4. PROGRAMS SPONSORED BY THE EPA Annual ______________________ Funding, $1000 NJ Category 850 A 37 A -- B A 30 B -- B 88 B PAGENO="0151" Dep~of Trans- portation Dept. of Trans - portation Natl. Bureau Std. - Boulder Stevens Institute General Electric (Tempo) Naval Syst R&D Lab Annapolis Univ. of Calif. Los Angeles Cornell Univ. Contractor Stanford Research Institute Univ. of Mass. Table 5. PROGRAMS SPONSORED BY OTHER GOVERNMENT AGENCIES Annual _____________________________ Funding, $1000 125 sponsor Nati. Sci. Foundation Natl. Sci, Foundation Dept. of Commerce Advanced Research Projects Agency, Department of Defense Inve stigation Technology assessment of hydro- gen energy Use of hydrogen storage and trans- mission in off-shore windmill and nuclear power systems Bibliography and literature - search on hydrogen Survey of production, storage,and use of hydrogen 150 Systems studies of use of hydrogen as a military fuel 75 Field trials of a hydrogen-fueled gas turbine ship; hydrogen embrittlement 75 studies Field-testing of liquid-hydrogen-fueled jeep; hydride storage 55 Emissions from hydrogen-fueled engines 30 Category A B B B B B PAGENO="0152" Table 6, Part 1. PROGRAMS SPONSORED BY INDUSTRY Annual Sponsor Contractor ~ Funding,$1000 Catego~y_ Northeast Utilities General Atomic Production of hydrogen by thermochemical water-splitting B Southern Calif. Edison Co. General General Electric Production of hydrogen by Electric (,gchenectady) thermochemical water - splitting B General General Electric Electric (Lynn) Electrolyzer development B Northeast Utilities Burns and Roe System study for hydrogen transmission B 0' Niagara Mo- `hawk Power Co. In-house Hydrogen off-peak electricity storage B Mountain Fuel Billings Energy Hydrogen appliance conversion B Supply Co. Research Southern Calif. IGT Appliances to use hydrogen on Gas Co. hydrogen-rich fuels A Winnebago and Others Billings Energy Conversion of motor home and other Research vehicles to run on hydrogen B Public Ser- vice Electric and Gas Co. In-house Electrolyzer, hydHde storage, and fuel cell system demonstration and evaluation B Texas Gas Transmission KMS Fusion, Inc. Production of hydrogen from laser Corp. `fusion reactors B PAGENO="0153" Sponsor ______________________ American Iron and Steel Insti- tute Allied Chemi- cal A. G. A. Rocketdyne Isotopes, Inc. (A subsidiary of Teledyne, Inc.) General In-house Motors Beech Air- craft In-house Minnesota Valley En- In-house ginee ring Westinghouse In-house Electric Utili- Pratt & Whitney ties - Gas Aircraft Utilities Business In-house Communications Table 6, Part 2. PROGRAMS SPONSORED BY INDUSTRY Annual Contractor Investigation Funding, $1000 Category Bethlehem Steel Production of steel using hydrogen from nuclear ene rgy - - B In-house Hydride storage, basic research -~ B IGT Thermochemical hydrogen production 250 A tn-house Hydrogen embrittlement and pipe - line materials research - - -- tn-house Electrolyzer development -- B I. on-board automobiles 3 B Liquid -hydrogen storage tanks for automobiles 3 B Liquid-hydrogen storage tanks for automobiles B High-temperature electrolyzer devel- opment C Fuel cell development - small prog- ram onhydrogen cells B Hydrogen-energy system assessment C PAGENO="0154" Sponsor Boeing Aero- space Co. Consolidated Edison Co. of N.Y. Northeast Utilities Southern Calif. Edison, Oak Ridge Na- tional Lab., and General Electric Northeast Utilities Table 6, Part 3. PROGRAMS SPONSORED BY INDUSTRY Contractor In-house Brookhaven Nati. Lab Futures Group General Electric (Tempo) In-house Annual Investigation Funding, $1000 Categ~y Hydrogen fuel systems - - B Development of storage device for hydrogen as a hydride B Feasibility of energy delivery system based on hydrogen B Eco-energy (Advanced Concepts in Energy Systems Using Hydrogen) B Storage of hydrogen B. PAGENO="0155" University of Miami University of Denver Cornell University M. I. T. University of Miami Unh of Oklahoma Oklahoma State Univ. Unix of Washington* Avco Corporation United Aircraft Southwest Research University of Calgary * Seattle Light and Power, General hydrogen systems studies and literature review Hydride research Hydrogen embrittlement of steels Hydride -8torage system study Hydrogen-engine research Hydrogen-engine research Hydrogen-engine research Hydrogen-energy system research Thermochemical hydrogen Liquid hydrogen as an aircraft fuel Use of hydrogen as a military fuel Hydrogen-engine research C C C C C. Table 7 U. S PROGRAMS WITH UNKNOWN SPONSORS Annual Contractor Investigation Funding, $1000 Category C C C C C C C * :~ PAGENO="0156" Table 8. OVERSEAS PROGRAMS Sponsor Contractor EURATOM Joint Nuclear Research Center, Ispra, Italy - - Kernfurschungsanlage, W. Germany - - Unlu of Aachen, W. Germany Gaz de France In-house and at five universities ElectrlcIt~ de France tn-house Pechiney Ugine Kulmann, Paris In-house Inst. for Applied Sys- tems Analysis Brazilian Govt Japanese Govt British Steel Corp. (Austria) Battelle, Geneva Philips, The Nether- lands Fianaciadona de Estudo e Projetos Misc Japanese agencies Hydrogen-energy systems studies Hydride-storage research Hydride research Hydrogen-energy systems study, transmission research Hydrogen-energy storage and trans - mission as part of the solar energy program Use of nuclear hydrogen in steelinaking Annual Investigation Funding. $1000 Thermochemical hydrogen produc- tion, materials research, and systems study 2000 Thermochemical hydrogen produc- tion from high-temperature nuclear reactor Thermochemical hydrogen production Thermochemical hydrogen production, transmission, storage research Electrolyzer develoDment, fuel cells Thermochemical hydrogen production Category A B B B B B B C C B B 1000 In-house PAGENO="0157" Table 8, Cont. OVERSEAS PROGRAMS ~po~sor Contractor Shell Research Ltd. In-house (England) Daimler-Benz IGT British Gas - British Elec- tricity - - German Ministry of Research 7 German companies Atomic Energy of Canada, Ltd. - - Steel Co. of Canada In-house Study of thermochemical hydrogen production - use of hydrogen in industry Use of hydrogen in iron and steel production C A C C hive stiuatinn Annual Funding, $1000 Category Hydrogen-energy studies Study of problems in hydrogen- fueled vehicles Hydrogen-energy system assessment Electrolytic hydrogen-storage study Comprehensive review of hydrogen as a future fuel CJ~ C C C PAGENO="0158" Table 9. COMPLETED PROJECTS (Excluding A.G.A.) Sponsor Contractor~~ Office of Set. Brookhaven Nati. Lab and Technol. Office of Sci. Oak Ridge Natl. Lab and Technol. Dept. of Defense Army Engineers 1.) C') NASA NASA-Johnson NASA NASA-Langley NASA NASA-Langley Northeast Utilities Southern Calif. Edison Co. Hudson Insti- tute Objective Energy technology assessment Hydrogen and synthetic fuels - study panel "Energy Depot" - nuclear-based synthetic fuel study Summer program -hydrogen energy Energy supplies for aircraft 2-day workshop on hydrogen air- craft Hydrogen-energy system study Hydrogen systems for electric energy Hydrogen-energy system study 1971 A 1972 A 1970 B 1973 A 1973 A 1973 A 1972 A 1972 A 1972 A Futures Group General Electric (Tempo) In-house PAGENO="0159" 153 INSTITUTE OF GAS TECHNOLOGy HYDROGEN-ENERGY TECHNOLOGY - TODAY AND TOMORROW by Derek P. Gregory Paper Presented at SECOND ENERGY TECHNOLOGY CONFERENCE Washington, D.C. May 12-14, 1975 k 3424 SOUTH STATE STREET tID'F EDUCATION RESEARCH AFFILIATED WITH ILLINOIS INSTITUTE OF TECHNOLOGY PAGENO="0160" 154 5/75 ENERGY TECHNOLOGY II Hydrogen-Energy Technology - Today and Tomorrow Derek P. Gregory Director, Energy Systems Research Institute of Gas Technology Chicago, Illinois 60616 Abstract The concept of using hydrogen as a possible alternative to electric power to carry energy from central energy-production stations directly to the user has received an increasing amount of attention in the past 2 or 3 years and is now the subject of a considerable amount of study and research effort in various parts of the world. This paper presents a brief review of some of the ongoing research projects and discusses some technological and policy requirements that are needed before hydrogen can be considered as a signi- ficant and viable future alternative to the fossil fuels. The scope of this paper is confined to the potential role of hydrogen as a fuel gas and does not extend to the important role that hydrogen must play in the production of syn- thetic fuels from fossil energy resources. Delivery of hydrogen as a fuel gas is the only way that the almost 30% of the nation' s overall energy needs now being supplied by natural gas can be supplied from nuclear sources without the complete replacement of both the energy-distribution equipment and the consumer' s plant. This 30% in- cludes much of the domestic heating and cooling, industrial processing, and * industrial steam-raising loads. For these "direct heat" applications, over- all energy system efficiencies of about 16% could be achieved today with hyd- rogen, compared with about 27% with electricity. Nevertheless, most of the hydrogen-energy research under way - and more is still needed - is aimed at increasing this overall efficiency. Values of 32% to 42% appear to be reasonable objectives. Research in hydrogen-energy technology appears to be technically justi- fied, and preliminary results are encouraging. However, a considerable investment in research by both industry and government will be required to make hydrogen acceptable from the standpoints of economics, abundance, and safety. Background Perhaps I should begin by outlining the basic objectives and advantages of a hydrogen-energy delivery system. Repeating this once again, in the light of the wide coverage already givgn hydrogen energy by the technical and popular press, may be superfluous to many people, but I believe it is important to ensure that the basic importance of the concept is understood and that my later remarks are not misinterpreted. When we look at the alarming decline in the availability of the conventional fossil fuels, particularly oil and gas, we can clearly see that a major shift must be made toward other energy sources - nuclear and solar being the most abundant and important. The use of conventional technology will stress the conversion of these energy forms into electricity for delivery to the cus- tomer. Because electricity is not readily storable, is expensive to transmit, and is not immediately useful in the vast majority of industrial and domestic PAGENO="0161" 155 ENERGY TECHNOLOGY II energy-consuming equipment, the alternative course of converting these non- fossil energy sources to a chemical fuel that is more compatible with today' energy distribution and utilization equipment has merit. In some applications, electricity will serve our needs best; in others, hydrogen will be superior. A mixed hydrogen-electricity energy-delivery system may well become the best long-term compromise. The attractiveness of using hydrogen as an energy-delivery medium de- pends upon the following assumptions* * Hydrogen may be produced from water by the input of energy, using electrolysis or thermochemistry, or by chemical reactions energized by direct solar or nuclear radiation. * Hydrogen maybe transported as a fuel gas by long-distance pipelines in much the same way as we transport natural gas today. * Hydrogen can be stored by the same techniques used for natural gas storage - either in underground rock formations or by liquefaction. * Hydrogen may be delivered to existing gas customers in existing gas distribution pipes, and burned in existing gas-combustion equipment that has undergone only minor modifications. If these assumptions are valid, then hydrogen made from tomorrow' s nuclear or solar energy can, in principle, replace today' a natural gas with only a minor disruption of the consumer' s equipment. The use of hydrogen is the only way that the 30% of national energy needs now being supplied with naturaFj~s can be provided with nuclear-based energy without the complete replacement of the already existing distribution and consuming equipment. Research work already carried out has shown a) that electrochemical, thermochemical, and radiochemicalprocesseg for the production of hydrogen are all technically feasible, but require increasing technological advances in the order shown; b) that pipeline transmission and distribution of hyd- rogen is technically feasible at costs that are~ significantly below those of moving electricity; c) that the storability of hydrogen either underground or as a liquid is feasible; and d) that this feature could lead to considerable savings resulting from improvements in the load factors of the generation and transmission facilities. On the negative side, however, the overall effi- ciency of a hydrogen-energy delivery system, using conventional technology available today, will be somewhat less than that of an all-electric system. It is thus assumed to be economically unattractive. Although it may be possi- ble to trade this loss in efficiency for the economic advantages of trans- mission and storage, much of today' s hydrogen-energy research is directed toward improving the efficiency of hydrogen-energy systems and is mainly aimed at the hydrogen production stage. Sparked by the promise of a hydrogen-energy analog of the natural gas system, some enthusiasts have broadened the scope of the concept to allow other attractive features of hydrogen energy to be exploited. Because hyd- rogen is the lightest of all fuels (51, 500 Btu/lb compared with 18, 500 Btu/lb for jet fuel), it is a superior aircraft fuel, and much has already been done to tackle the problems confronting its use in this application. Because it is almost nonpolluting, its use as an automobile fuel would eliminate many environmental problems, which has stimulated research into this applica- tion. In these applications where specialized advantages can be claimed, the objective of using hydrogen is not dependent upon producing it from non- fossil fuels. For this reason, the production of clean hydrogen from coal could be considered for use in these applications. Finally, the ready `inter- changeability" of electricity and hydrogen, via the electrolyzer and the fuel cell, has stimulated research into the possible use of hydrogen storage as a peakshaving or load-levelling device for electric utilities. Present Research Activities Significant hydrogen-energy research began in the United States and in Italy 4 or 5 years ago, and has now expanded to include work in Canada, Brazil, Switzerland, Australia, Japan, West Germany, France, and England. 2 62-332 0 - `76 - 11 PAGENO="0162" 156 ENERGY TECHNOLOGY U Even though early work concentrated on the concept of the overall `hydrogen economy," a concept in which hydrogen produced from nonfossil fuel is used as a universal fuel for almost every energy application, many of the efforts today are aimed at one or more of the rather smaller segments of the over- all concept - the production and use of hydrogen as an energy form for some specialized applications. Most of today' s hydrogen-energy research is concerned with the production of hydrogen from water. The production of hydrogen by electrolysis, using electric power, is a way of using known technology and existing generating equipment. Electrolysis technology is available today; indeed, several large electrolyzer plants are in operation (although none in the United States), producing electricity from hydrogen at an efficiency of about 70%. Several quite small research programs are aimed at making improvements in elec- trolyzer efficiency, without significantly increasing capital costs. Most re- searchers in the field believe that electricity-to-hydrogen efficiencies in the 90% to 95% range can be achieved, so that overall heat-to-hydrogen effi- ciencies of 35% to 38% can be predicted, using advanced nuclear-electricity generation technology. To achieve these higher electrolyzer efficiencies, there is a need for the development and testing of new materials capable of withstanding higher temperature operation than at present, and there are benefits to be gained from the operation of electrolyzers at high pressure, which would allow hydrogen to be delivered directly to the pipelines. How- ever, because the electrolyzer-manufacturing industry is a small one, it cannot afford to fund the research necessary to make dramatic improve- ments in its product. Such research must be supported by the potential users of the hydrogen that these improved electrolyzers would produce. A second hydrogen-production method, and the one that is receiving the most research support today, is the thermochemical splitting of water, using a nuclear or solar heat source, without an electrical intermediate. Heat is used to drive a number of chemical steps in a cyclic sequence, all the components of the cycles, except water, hydrogen, and oxygen, being recycled. Although no commercial technology is available for this process today, several re- search groups are conducting experimental trials of chemical reactions, and an even greater number have carried out detailed thermodynamic analyses of the theoretical efficiencies of various cycles. Much of this work is held proprietary by the researchers. The Institute of Gas Technology (IGT) has identified some 70 theoretically possible cycles, several of which possess calculated heat-to-hydrogen efficiencies greater than 50%. In contrast, nu- clear heat-to-electricity efficiencies are at present only about 35% and are only expected to rise to about 45% in the future. One of the chief concerns about the commercial application of nuclear thermochemical hydrogen production is the need for a special type of nuclear reactor, probably the high-temperature gas-cooled reactor (HTGR) capable of delivering high-temperature heat to a chemical process rather than to an electricity generator. Such a reactor, needed to produce the high effi- ciencies discussed earlier, would require several years of speciaized nuclear engineering. Although such development is already going on, it appears to be the "poor relation" of the nuclear industry. We recognize that the lead times required to develop a substantial business to produce thermo- chemical hydrogen are very long - about ZO years or more. A small amount of work is going on in the area of hydrogen transmission, mainly to calculate the cost of moving hydrogen in pipelines over long dis- tances. IGT' s studies have shown that, using natural gas pipeline technology, transmission costs over several hundred mile distance are about 3. 5/ to 5. 5~/million Btu-lOO miles, in contrast to overhead electrical transmission costs of 40/ to Sl.05/million Btu-lOO miles. Our studies have also shown that the energy needed to pump hydrogen through a pipeline is less than 1% of the total energy throughput per 100 miles, compared with an energy loss of about 10% in moving electricity over the same distance. Investigation of the effectof hydrogen on the embrittlement of conventional pipeline steels has just begun in several laboratories; no research results have yet been published. 3 PAGENO="0163" 157 ENERGY TECHNOLOGY U Conceptual, system, and techno-economic assessments of the prospects for moving energy from offshore wind- and solar-power stations using hyd- rogen pipelines or seagoing tankers have also recently commenced. The storage of hydrogen as a chemical hydride is receiving significant research attention. Hydrides of magnesium, iron-titanium alloys, and the rare earths can all be formed spontaneously by reacting the finely divided metal with hydrogen gas; the hydrogen can then be recovered by heating the hydride. Because waste heat is released in `;he hydride-formation step, the storage process is not 100% efficient. In general, known hydrides are either too inefficient, too heavy, or too costly to be completely satisfactory for mobile storage applications (e.g., for hydrogen automobiles). Small programs of basic research on the understanding of alloy hydride chemistry are under way in the hope that improved formulations can be developed. Meanwhile, engineering studies on relatively large scale stationary storage systems using an iron-titanium alloy hydride are aimed at the electrical peakshaving application. Hydrogen can alsobe stored byliquefaction or in underground rock form- ations or depleted gas and oil wells. Some studies to improve the efficiency of hydrogen-liquefaction processes have been begun, but no work appears to be in progress to demonstrate the feasibility of bulk underground hydrogen storage. The utilization of hydrogen as an automobile fuel has received much well- publicized attention, but, in fact, remarkably little funding has been applied to this application. Some "over-the-road" demonstrations, carried out by student teams on "shoe-string budgets," have done little more than to show that itis relatively easyto convert conventional automobile engines to operate well and extremely cleanly on hydrogen. The major and unsolved problems are in the handling of the fuel itself, both in the vehicles and in the distri- bution and storage network needed to supply the refueling stations. At this time, surprisingly, very little reliable and systematic data are available on the actual test-bed performance, efficiency, and emissions of hydrogen engines; on the design of engines specifically engineered to take advantage of the properties of hydrogen; or on such fundamental information as the octane number of hydrogen, which appears to be well over 100. The use of hydrogen as an aircraft fuel has been discussed a great deal. Design studies that have recently been completed for hydrogen-fueled wide- bodied passenger jet aircraft show very considerable potential improvements in efficiency, performance, and noise over the conventional jet-fueled version. Even though NACA (the predecessor of NASA) actually flew a hydrogen-fueled experimental jet aircraft in 1956 and an aircraft gas turbine specially designed to operate on hydrogen was developed and tested in industry at about the same time, since then no actual tests of a hydrogen-fueled airplane have been con- ducted, nor are there any plans to do so known at this time. I believe that the regulators, valves, meters, and pipework now used in conventional gas systems will be compatible with hydrogen, but, apparently, no significant testing or demonstration of this aspect of hydrogen' s appli- cation has been carried out yet. Similarly, the use of hydrogen in conven- tional natural-gas-fired burners appears to require only minor burner modi- fications, but, to date, detailed design and testing of modified burners has not been a significant feature of any hydrogen-energy research program. Although no major conversion problems are envisaged, I am surprised that this particular end-use aspect of hydrogen energy has received so little attention, in contrast to the use of hydrogen in automobiles and aircraft. Fifty-two percent of the total U.S. energy consumption is used for combined space heating, industrial process heating, and industrial process steam appli- cations. About half of this amount if now being supplied by natural gas. The natural-gas-fueled equipment used in these applications could seemingly be converted to hydrogen far more easily and far more cheaply than to electri- city. Not many people realize that the amount of energy used in the United States to produce industrial process steam alone is 17% of the total energy budget, about the same as that used to drive all the automobiles in the country. 4 PAGENO="0164" 158 ENERGY TECHNOLOGY II It seems to me that the conversion of this sector of the energy market to nonfossil fuels, viahydrogen, shouldreceive as muchemphasis as the efforts now being made to develop hydrogen-fueled or battery-operated automobiles. Some significant work is under way on the development of catalytic burners for use with hydrogen. Since hydrogen oxidizes (rather than burns') at low temperatures without a flame on a catalyst bed, this technique has merit for many domestic and industrial heat applications. A nonflame catalytic hydrogen burner canbe made to produce no nitrogen oxides, and because its only com- bustion product is water, can be operated without a vent or flue. At IGT, hydrogen-fueled water heaters with efficiencies of about 85% have been demon- strated, and without a flue, 100% of the heating value of hydrogen can be used in a space heating plant. The importance of these developments is apparent - when we consider the efficiencies of hydrogen versus electricity systems. Overall System Efficiency Recently, an efficiency comparison of a hydrogen system and an all- electric system was published (Ref. 1) in which the automobile was chosen as the end-user of the energy. The relative overall efficiencies, starting with nuclear heat and ending with useful work at the wheels, were hydrogen, 3% and electricity, 19%. These figures were derived by assuming the effi- ciencies for the various parts of the system, as shown in Table 1. Table 1. COMPARISON OF ELECTRIC AND HYDROGEN ENERGY SYSTEMS, ACCORDING TO SIMPSON (Ref. 1) Hydrogen System % Electric System Therrno-electrochemical Plant 65 Nuclear Electric Plant 35 Hydrogen Pipeline 90 Electric Transmission 90 Hydrogen Liquefier 50 Battery Automobile 60 Hydrogen Automobile 10 Overall 3 Overall 19 Even though I would argue about the relative transmission efficiencies of hydrogen versus electricity (especially over very long distances) and with the efficiency assigned here to the hydrogen automobile (which corresponds to that of a gasoline car with its pollution control equipment), I am forced to agree that the hydrogen automobile will use more nuclear fuel than its electric counterpart. To do a complete comparison, the relative costs of an electric vehicle and its energy-delivery system must also be compared with those of the hydrogen version: neither set of costs are known as yet. Let us look, however, at the "direct heat" applications of energy, the applications, which include domestic space heating, industrial process heating, and industrial steam-raising, are accounting for 52% of U.S. energy demands, and are much more attractive applications than the automobile for pipeline hydrogen. Following the technique applied in the automobile example, we can draw the comparisons shown in Table 2. 5 PAGENO="0165" 159 ENERGY TECHNOLOGY II Table 2. COMPARISON OF VARIOUS HYDROGEN- AND ELECTRIC ENERGY SYSTEMS FOR THE "DIRECT HEAT' APPLICATIONS Case 1. Electrolytic Production, Existing Combustion Equipment, Today' s Technology Nuclear-Electric Plant 30 High-Pressure Electrolyzer 75 Hydrogen Pipeline (100 miles) 99 Hydrogen Heating 70 Overall 16 Case 2. Thermochemical ?roduction, Catalytic Combustion Equipment, Future Technology Nuclear-Thermochemical Plant 50 Hydrogen Pipeline (100 miles) 99 Hydrogen Heating 85 Overall 42 Case 3. Electrolytic Production, Catalytic Combustion Equipment, Future Technology Nuclear Electric Plant 40 High-Pressure Electrolyzer 95 Hydrogen Pipeline (100 miles) 99 Hydrogen Heating 85 Overall 32 Case 4. All-Electric System, High-Temperature Nuclear Reactor Present Future Technology Technology Nuclear Electric Plant 30 40 Electric Transmission (100 mites) 90 90 Electric Heating 100 100 Overall 27 36 In Case 1, we consider present technology, using electrolyzers and conven- tional gas-burning equipment, involving no major replacement of user' s equip- ment. In Case 2, we consider what might be achieved with a successful thermochemical production development and the replacement of consumer' burners with efficient catalytic burners In Case 3, we assume a significant, but not unreasonable, improvement in electrolyzer efficiency, coupled with the use of catalytic burners. In Case 4, the all-electric case, complete 6 PAGENO="0166" 160 ENERGY TECHNOLOGY II replacement of the delivery system and the utilization equipment is assumed. Efficiencies for the hydrogen-system components have been assigned accord- ing to values calculated or measured in lOT studies. Two different electricity- generation efficiencies are shown: one corresponding to what is achieved in today' s "conventional' nuclear plants and one corresponding to future tech- nology reactors operating at higher tempe~atures. A full treatment of energy efficiencies cannot be presented at this tine; these figures are to be used only as 4uidelines. However, Table 2 do~s make it apparent that hydrogen- energy efficiencies do not fundamentally have to be lower than electricity efficiencies, but that improvements to both production and utilization parts of the system will have to be made. Actions Required for Hydrogen-Energy Development I would like to close my remarks with a list of policy actions that I be- lieve are required by industry and by government to accelerate a proper evalu- ation of the hydrogen-energy option, and to develop technology in those areas needed to bring about major use of hydrogen as an "energy vector." What actions are needed by the utility industry today? 1. Companies that deal with natural gas need to take positive action to demonstrate to their investors that they have prospects for participating in a "perpetual" energy industry that is not subject to another resource depletion. 2. Suppliers of natural gas must convince their customers that a supply of a gaseous fuel is reasonably ensured for at least as long as the expected life of any new gas-using plant that they are about to install. 3. The utility industry must demonstrate to government policy- makers that a nuclear-hydrogen energy delivery system is indeed a viable alternative to an all-electric economy, that the industry will be ready to operate such a system as soon as it becomes economically justified, and that, in doing so, it will not be thrusting upon the public a new, untried or unwelcome form of fuel. 4. The all-gas utilities must soon decide whether they will own their own nuclear plants or rely on the purchase of the product. They must also decide whether this product will be electricity, heat, or hydrogen. Some form of cooperation with the electricity- generating utilities seems inevitable because these utilities have a 15 to 20 year lead in the experience of constructing, owning, and operating such plants. 5. The utility industry must soon persuade the nuclear industry to prepare to increase the growth rate of nuclear capacity to be able to meet the energy needs of many new and existing gas cus- tomers, as well as electricity customers, by the end ofT!~ century. To specify the number and types of nuclear plants necessary for hydrogen generation in the year 2010 will require that a considerable research effort into hydrogen production tech- nology be undertaken immediately. The utility industry cannot hope to make these impacts based on the meager level of study and research currently being conducted. If the industry is to hope to demonstrate that hydrogen can be economically competitive with elec- tricity, more research is needed to improve the efficiency and economy of both electrolytic and thermochemical hydrogen production. If it is to convince the public, its customers, and the regulatory bodies. that hydrogen is indeed a safe and viable all-purpose fuel, the utility industry must extend research to the transmission and, especially, the distribution, utilization, and safety areas. 7 PAGENO="0167" 161 ENERGY TECHNOLOGY II What Government actions are needed? I believe that Federal Government researchand planning efforts in the area of hydrogen energy should be better coordinated than they are at present. The following actions are required: 1. The hydrogen-energy option should be examined as thoroughly as corresponding work - for example, on electricity transmission, battery storage, and electricity utilization. An appropriaterespon- sibility for the development of alturnative energy-delivery systems (not just storage systems) should be specifically assigned within the Energy Research and Development Administration (ERDA). 2. The hydrogen programs that were initiated by the Atomic Energy Commission and NASA before the formation of ERDA should be con- tinued without the temporary interruptions that now appear likely. These programs currently include electrochemical and thermochemi- cal hydrogen production, hydrogen storage, and the utilization of hyd- rogen in fuel cells, automobiles, and aircraft, and should be broadened to include the residential and industrial use of hydrogen for `direct-heat' applications. 3. Cooperative programs between the utility industry and Government agencies must be developed in hydrogen-energy areas to ensure that the long-range decisions of each are compatible with those of the other. 4. ERDA should collaborate with the nuclear industry and the gas industry to formulate a growth plan that will accommodate future gas and electric energy demands. It is important to recognize the long lead time (approaching 20 years) involved in implementing a substantial nuclear-hydrogen production industry. 5. ERDA should support a program of research and development on the special nuclear reactor engineering for high-temperature reactors of the type required for thermochemical hydrogen pro- duction. Neither the Conventional Pressurized-Water Reactors nor the Liquid-Metal Fast Breeder can provide high enough temp- eratures for this process. Conclusion After 3 or 4 years of preliminary research into the hydrogen-energy concept, I believe that we can make a strong case for its serious consid- eration as a long-term contributor to the U.S. energy system - at least a strong enough case to justify as significant research and demonstration effort as is now being applied to other concepts suchas superconducting trans- mission, battery storage, and some advanced solar energy systems. I also believe that the outstanding problems have been well-enough defined to allow a properly balanced research program to be formulated. What is not clear, at present, is what the relative roles of Government and in- dustry should be and where such a program should be located within the Government' s research organizations. Reference Cited 1. Simpson, J. W., "Nuclear Energy and the Future," Fortune 91, 41- 45 (1975) February. - SG/JM 8 PAGENO="0168" 162 Derek P. Gregory Dr. Derek P. Gregory is Director, Energy Systems Research at the Institute of Gas Technology in Chicago. His prime interests are concerned with worldwide energy resources and the deveiopmentpf systems to convert the more abundant resources into clean and convenient energy forms. He has been at IGT since 1970, where he is responsible for research on fuel cells, hydrogen fuel systems, alternative synthetic fuels, and novel gas-fueled appliances. He graduated from the University of Southathpton, England, and carried out research for his Ph. D. in electrochemistry at Southampton. After some nuclear materials work at the Atomic Weapons Research Establishment, Alderrnaston, he joined Shell Research Ltd., to work on basic fuel cell research at their Thornton Research Center, Chester. Later, he moved to the U. S. and joined Pratt & Whitney Aircraft~ where he was responsible for applied research on fuel cell projects, and became closely involved with the engineering aspects of fuel cell systems. In 1966, he returned to England to join Energy Conversion, Ltd., as Research Manager, responsible for research on fuel cells and high energy batteries. He returned to the U. S. to IGTin 1970. Dr. Gregory is the author of several technical papers and two textbooks on fuel cells, batteries, and. automobile fuels. PAGENO="0169" 163 Dr. GREGORY. I would like at this time to make some somewhat less formal comments in summary. We have had a program ~ !hydrogenenergy at IGT under my di- rection for about 5 years. We have depended on support for this ~)rOgram from the American Gas Association and the Electric Power Research Institute, NASA, the NSF and from some industrial corn- panies, Mr. Chairman. At present, we have no ERDA projects, as such, on hydrogen energy. Now, I would like to tackle a number of questions that are raised about hydrogen, such as why we need hydrogen as a synthetic fuel. I think that your committee has already heard a number of ad- vantages claimed for a fluid chemical fuel: A gaseous or liquid fuel. We think it is obviously important to keep an existing system intact so as to be able to use the fuels that would be available when we go into future. raw energy supplies of nuclear and fossil fuels. Hydrogen does supply a possible means to link up the conventional users of gas-using equipment with the future raw energy supplies. The advantages of hydrogen, such as the storage and long distance transmission capabilities have been much talked about. I think its major usefulness is in being able to use hydrogen as gaseous fuel in existing oil- and gas-burning equipment w-ith only relatively minor inodificat ions. Why not go to electricity as the link between nuclear and solar energy and conventional use? We certainly should do that, too, al- though electricity has its problems. It is not so easy to store. Trans- mission tends to be expensive compared to moving conventional fuels. Therefore, the cost of delivered electricity is rather expensive. We feel that a. mixed energy delivery system that. uses hydrogen and electricity is an ideal optimum to strive for in the future. As to coal conversion, where does the gasification of coal to syn- thetic natural gas fit. in? The conversion of coal to fluid fuels will play an important role in the future. As a long-term investment, we also have to look beyond the time when coal availability begins to dccl inc. Hydrogen is a synthetic gaseous fuel that can be made from coal. It. can be integrated with nuclear and solar energy. In the longer time scale, hydrogen appears to be more attractive. In the shorter time scale, if you have the. coal, you should convert it to an existing con- ventional fuel such as methane or oil. Hydrogen will play a very important role in the chemistry of the conversion of coal and shale to synthetic fuels. That. is outside t.he scope of what we are talking about. here today. My rema.rks are confined to the use of hydrogen, specifically as a. fuel, not as a feedstock into the synthetic fuel l)I'Oduction. Now-, why do we select hydrogen? Where do we stand today in the technology? Hydrogen production is somewhat unique. We can make hydrogen from a. w-hole variety of raw energy sources. It. can be made from coal, nuclear energy. solar energy, from all forms of this, such as windpower. hydropower and agricultural crops; also waste ma- terials. Thus, like electricity, it is a universal secondary energy form that can be produced from a wide range of raw energy courses. There are three primary methods of making hydrogen from non- fossil fuels. The first is electrolysis of water, which is used in industry PAGENO="0170" 164 today. Compared to other ways of making hydrogen in progess today, electrolysis is considerably more expensive. lVhen we looked into the reasons for this. we found that this is really because the cost of the process is tied closely to the price of elec- tricity and the. efficiency of the overall process is closely t.ied to the efficiency of electricity generation. We believe today~ with electric or electricity generation. say. at about 30 percent efficiency. and that the electrolyzer, at about 70 percent. We have, an overall conversion of heat to hydrogen of 20 perceiit. That is not very promising. Therefore. we believe, by improving technology now in both in electricity generation and in the electrolyzer itself. that we can get this to 50 percei~t overall efficiency. The cost of the hydrogen using 10 mill power would be in the order of ~5 to $8 pt" million Btii's. This represents a fairly expensive fuel price. Mr. ~`IcCoR~rAcK. Virtually all of the cost is the cost of electricity? Dr. GREGORY. About two-thirds. About two-thirds of this is elec- tricity and one-third is the amortization of the plant. The second process is thermochemical hydrogen production. WTe have quite a. lot of experience with this. This is a cyclic chemical sys- tem in which heat is used to drive a number of chemical reactions. All the components of these reactions except for water going in and hydro- gen and oxygen coming out are recycled. We need a lot more chemical engineering work in this technology. But not only do we need a. lot of development in chemical engineering: this kind of process also needs a high temperature source of heat. 1.800 to 2.000 degrees Fahrenheit. As far as nuclear sources are concerned, we. have to have parallel development to push the temperature of the. existing high temperature nuclear reactors up by about 200 degrees beyond where they are. The cart is in front of the. donkey here.. The efficiency from heat. to hydrogen by a thermochemical process promises to be in the 40 percent to 50 percent region. We thus have the opportumty to be able to beat the electrolysis method on an overall efficiency basis. The cost of thermal chemical production is not yet known. The third process is the use of direct. radiation to decompose water. There are speculative research projects going on. using neutron radia- tion directly from a fusion type of reaction oi radiation of sunlight in some photochemical Process. I think you nmst remember that these processes are possible options to make hydrogen, although they are very much in the speculative stage. As to the transmission of hydrogen, you can move hydrogen in con- ventional natural gas transmission pipes. The tecimology that we have suggests that the natural gas system is probably OK for hydrogen, although not yet. put. to the test. There is, however a question of em- brittlement. WTe believe, with present pipelines and materials, that as long as you keep pi'essm'es down to that usedl in pipelines today, then we will be OK. The cost of hydrogen transmission is of the order of 3 to 5 times lower than those of overhead electric transmission and it may be as much as 50 to 100 times lower than underground electric transmission. This provides the incentive to look at hvdlrogen as a long dlistance t.ransmissioii option. PAGENO="0171" 165 The local distribution equipment used today for natural gas should be compatible with hydrogen. It has not been put to the test, how- ever, Mr. Chairman. As to the storage of hydrogen, we hear a. lot said that hydrogen is easy to store. It really is not "easy." It is certainly easier to store tha.n electricity, but it is harder to store than oil. We should not kid our- selves that hydrogen is an easy material to store. It is easy to store it as a high pressure gas, but the costs are prohibitive. Hydrogen can be stored in bulk rather less expensively by condensing it to a liquid. We have the technology to do this but the efficiency of liquefaction is 70 percent to 80 percent.. If we put the hydrogen into a chemical storage form__for instance a metal hydride_-the, efficiency is between 70 per- cent and 90 percent. The underground storage of hydrogen looks as though it is a cheap and efficient way of storing large quantities of energy. We do this with natural gas. It is only appropriate on a scale applicable to large scale bulk storage of hydrogen. It is untried, but there appears to be no reason why it shouldn't work. Considering solar energy systems where the need for bulk en- ergy storage, which is vital, hydrogen storage appears at this time to be very attractive. In the use of hydrogen, we can burn hydrogen in conventional gas burning equipment if we modify the burner slightly. If you put hydro- gen into an existing burner, it will flash back because of the high flame speed. We know how to convert burners, although the conversions them- selves, to some extent, are untested. We believe that one can mix hydro- gen into natural gas up to 8 percent to 10 percent by volume before you get any flashbacks. This represents something that is somewhat un- tested, but very important. The modification of industrial equipment is going to be easier than that of domestic equipment. It is run under more controlled condi- tions and there are fewer burners to convert. I think at this time that one has to look at the comparison of the conversion of industrial gas and oil burning furnaces to allow them to run on hydrogen, and to compare this with the problems of converting the equipment to run on electricity, the other long terni option: Conversion to hydrogen seems simpler and cheaper. I would like to mention the prospects for catalytic burners. Hydro- gen will oxidize at low temperatures on a c~ttalyst. One can devise catalytic burners which burn hydrogen without flames very cleanly with no pollution, also very efficiently. These are still very much in the laboratory stage but they do look very promising at this time. Hydrogen is used today as a feedstock in the chemical industry. It is used to make ammonia, which producers fertilizer; it is used to make methanol and it is also used in the refinery business; in the future hydrogen will be used in steelinaking. It will be used for synthetic gaseous and liquid fuel production. These. needs are relatively small compared to the needs that we see at this time to meet. the unfilled de- mands for liquid fuels and gaseous fuels. By the year 2000 we will need 5 or 6 times as much hydrogen to fill the deficit in natural gas thaii we will need to provide, all of the industrial hydrogen we forsee being used for the chemical feedstock uses. PAGENO="0172" 166 The use of hydrogen in engines is important. Automobile type en- gines will run cleanly and efficiently on hydrogen with minor modifi- cation to the carburetor. The problem is more with the fuel tank and fuel distribution system: (how to get hydrogen to the gas station) than how to actually run the engine. I would like to make a. special case for hydrogen as an aircraft fuel, say, for .domestic cargo and passenger carrying. There, you have a dif- ferent situation than with fighting aircraft referred to by the previous witness. The light weight of hydrogen offers a~ tremendous advantage in range and in takeoff weight. Hydrogen is the lightest chemical fuel we know of. There is only one-third of the weight involved compared to jet fuel on an energy basis. However, it is three times as bulky. You need three times as big a. fuel tank, but it weighs only one-tl~ird as much. Hydrogen, Mr. Chairman. is an extremely good fuel for fuel cells. The fuel cell development that. is now going on depends. to some extent, on converting the fuel feed to a hydrogen mixture before entering the fuel cell proper. Now; is the hydrogen energy option open to us now? I think that the answer to this question is "No." compared to electricity. We now know enough about the electricity system and of its economics to say that we can use it. As to hydrogen, we don't know enough about it in order to make up our minds. The major problems with hydrogen are: That it costs too much; the overall energy efficiencies are not high enough; there is some question about the compatibility of hydrogen with the existing delivery systems; and about the matter of safety. Mr. Chairman, I think that all of t.hese questions can be answered and solved by improved research and development. I would like to endorse the thought that we have to get the cost of nroduction down. What should be done? We should have an overall increase in research. But if we look at what is going on nationally, re- search at this time seems to be top heavy in the hydrogen production area. There s~ms to be a good reason to be doing research on the trans- mission and the utilization of hydrogen. It is all very well to learn to produce it cheaply. but we also have to learn how to use it. Therefore. I would like t.o see a setup on resea.rch in the production of hydrogen. hut I also would like to see more emphasis placed on use of hydrogen in stationary burners. Fifty-two percent of American energy consumption. That is about. t.he same number of Btu's needed to steam generation. Half of that is supplied by natural gas. These apph- cations represent somewhat simpler modifications to turn these over to hydrogen, than to convert, applications like automobiles and airplanes. The process steam used in industry alone accounts for 17 percent of our energy consumption. That. is about the same number of Btu's needed ot drive all the automobiles in the country. Hydrogen from nuclear or solar power could be considered as a way to get this large sector of industrial energy utilization over the nonfossil fuels in a. relatively simple way. I see no work going on in this direction at all. Now. in the storage area, hydrogen is being considered in the dee- tricity use. that is to say stored as hydrogen. and reconverted to elec- tricit~v on the way out. I would like to see more emphasis on using the stored hydrogen ~as a. supplementary fuel rather than converting this hack to electricity where ~ou suffer another efficiency loss. In the demonstration ~f the transmission and distribution of hyclro- PAGENO="0173" 167 gen, I would like to see more demonstration trials and experimental work to find out if we really can handle hydrogen in the existing nat- ural gas systems. We need to gain operating experience, safety infor- mation and confidence. If we look at the Government program on hydrogen at present, we need leadership; we need funding; we need coordination at this time. We know what to do. We can put a sensible, sound hydrogen program together. We took stock last December of what was going on in Govern- ment-funded hydrogen research. There were seven agencies involved, including the AEC, NASA, Environmental Protection Agency, NSF, DOD, Department of Transportation, and the Department of Com- merce. They all have hydrogen programs. There are hydrogen energy programs in six national laboratories and in five NASA field centers. At the time, this work seemed to be rather uncoordinated. I believe that a certain amount of duplication is occurring. Much the same situa- tion exists now, but there are certain efforts within ERDA to coordi- nate and plan the work. Where, in ERDA, does hydrogen fit? I find it, personally, difficult to see whether there is a real home for hydrogen energy research in ERDA. Perhaps it ought to fit with geothermal and advanced energy concepts. It is not a raw material or an energy source. It does not fit into the slot very logically. Electricity transmission and energy storage are in the domain of the conservation division. This is where, perhaps, hydrogen should fit to parallel electricity transmission work. I am concerned at this time that hydrogen technology might fall between the rungs of the ladder, because different divisions think it is the other guy's responsibility. I think that it is somewhat alarming that there has been no statement to say that hydrogen fits into this particular area. Finally, Mr. Chairman, I want to say that I feel that we have studied hydrogen, almost studied it to death over the last few years. Many repetitive studies are going on. There is the danger of losing the momentum gained in the Federal agencies and by the outside contract- ors by going into a holding pattern. I fear that some of the agencies that are sponsoring the work we are going back into the planning and review stage. We could lose a lot of momentum and time. I feel that this is a very urgent problem. Thank you, gentlemen. I will be glad to answer any questions later. Mr. MCCORMACK. Thank you, Dr. Gregory. That was an excellent statement. Our next witness this morning is Mr. Sidney H~ Law, Director of Research, Northeast Utilities. lie is accompanied by Mr. Michael Lotker, a scientist involved in advanced energy conversion research at Northeast Utilities. We will insert your entire statement into the record at this point. It is done without objection. You may speak as you wish or give a summary. STATEMENT OP SIDNEY H. LAW, DIRECTOR OP RESEARCH, NORTH- EAST UTILITIES; ACCOMPANIED BY MICHAEL LOTXER, SCIEN- TIST, NORTHEAST UTILITIES Mr. LAW. I would like to insert my prepared statement into the record and make my presentation much shorter, since my friend, Dr. Gregory, covered many of the areas that I was going to cover. PAGENO="0174" 168 Mr. M000RMACK. Very well. Your statement will be inserted into the record. Mr. Lotker's may also be inserted. [The complete prepared statements of Sidney H. Law and Michael Lotker are as follows:] PAGENO="0175" 169 TESTIMONY OF SIDNEY H. LAW, DIRECTOR - RESEARCH AND MICHAEL LOTKER, SCIENTIST, ADVANCED ENERGY CONVERSION RESEARCH NORTHEAST UTILITIES Before The Energy Research, Development, and Demonstration Subcommittee of the Committee on Science and Technology United States House of Representatives June 12, 1975 StINMARY: Northeast Utilities is one of a number of utilities that have been extremely interested in the potential for hydrogen energy systems over the past few years. We have supported several analytical studies in the past and are currently spon- soring work on thermochemical generation of hydrogen at General Atomics Company in San Diego. Ultimately we feel that there will be only four essentially non- depletable energy sources; fission, fusion, solar, and geothermal, and two energy transportation media; electricity and hydrogen. By as early as the l98Os, hydrogen generated from nuclear sources could have a wide impact on technologies ranging from fertilizer production to coal gasification. If generation efficiency can be improved sufficiently, it could later find wide use as a premium utility fuel for energy storage and peaking. This is, therefore, an important subject for our utility industry; we may be producers and marketers of hydrogen, taking full advan- tage of our financial and technical experience in management of large energy .con- version facilities, as well as consumers of hydrogen as a fuel. PAGENO="0176" 170 -2- INTRODUCTION: My name is Sidney H. Law, and I have been Director of Research of. Northeast Utilities in Hartford, Connecticut, for the past eight years. My associate, Michael Lotker, has been on my staff for the past three years and is concerned with advanced energy conversion research, including studies in the hydrogen energy systems area. He has authored several technical papers on hydrogen energy systems, and we both serve on various Electric Power Research Institute (EPRI), Institute of Electrical and Elec- tronics Engineers (IEEE), and Energy Research and Development Administration (ERDA) advisory committees. More complete biographies are included as Appendices A and B. We are happy to appear before you today to discuss hydrogen energy systems from a utility perspective. I will limit my remarks to the utility view since I am certain that other experts will have adequately discussed the technical details and broader implications of the so-called Hydrogen Economy. Since electricity is importantly involved in this view of our energy future, I prefer to call it the Hydrogen-Electric Economy and will refer to it this way in my testimony. I would also like to point out that while we have endeavored to examine the Hydrogen- Electric Economy from a utility point of view, the views reflected in this testimony are those of Northeast Utilities only. There is still no real consensus within our industry on the future or importance of such systems, although EPRI is currently evaluating them. NORTHEAST UTILITIES' INTEREST IN HYDROGEN: Northeast Utilities became interested in hydrogen energy systems through its par- ticipation in fuel cell research. Hydrogen is, of course, the ultimate fuel for PAGENO="0177" 171 fuel cells and can be easily piped to such power plants, located in individual neighborhoods, thereby reducing dependence on transmission and increasing effi- ciency with minimum impact on the environment. In 1972 we funded a study which assessed the Hydrogen-Electric Economy scenario in its entirety and concluded that there was indeed long-range promise in this concept. This study was followed up by a more narrowly defined consideration of the early application of hydrogen in connection with our proposed fuel cell work. Our continuing interest led us to formulate a program with General Atomic Company to identify and develop thermo- chemical cycles for generating hydrogen. The goal of the program, which has received nearly 400,000 dollars from our company to date, is to develop a technique for hydrogen production directly from nuclear heat at, a greater efficiency and consequently at a lower cost than is possible with electrolysis. Our interest in hydrogen is, we feel, a logical extension of our responsibilities in connection with electricity supply. Hydrogen, like electricity, is a synthetic energy medium or energy carrier. Both require attention to the technology of generation, transmission, distribution, and. consumption by the ultimate user. ELECTRIC UTILITY INTEREST IN HYDROGEN--WHEN? I would now like to discuss how electric utility interest in hydrogen may develop in the future. I've divided the future into three time frames: short range (1975- 1985), intermediate range (1985-2000), and long range (beyond the year 2000). Short Range (1975-1985): The only general use for hydrogen today in the electric utility is as a coolant for the windings in large electrical generators. Hydrogen will probably not be 62-332 0 - 76 - 12 PAGENO="0178" 172 important as either an energy storage medium or as a fuel for electric utilities during the next ten years (fuel cells, supplied by fossil fuels, could have an impact in this time frame however). Hydrogen may, of course, be in great demand in other sectors of the energy and chemical industry as those preceding me have detailed. Given a large demand at a premium price by such users, electrolytic generation of hydrogen in selected cases may well find a substantial market. This is especially true where advantage may be taken of relatively inexpensive sources of electricity, such as hydroelectric and, in special cases, off-peak nuclear generation. This would, of course, represent an electrical load for our industry which might eventually grow into a meaningful business activity. Intermediate Range (l985-2OOO)~ In the intermediate range, production capacity will expand to meet growing chemi- cal markets, and limited quantities of hydrogen may become available to utilities with particular environmental constraints as a premium peaking fuel. Then, if cheaper techniques are identified, hydrogen production as a fuel for intermediate loaded devices, such as fuel cells, may be viable. It is not likely that electrolysis will be the source of a significant amount of electric utility fuel since it would probably be more economical to use the original electricity rather than suffer the multiple inefficiencies of conversion to hydrogen and then back to electricity.. Of course, as the utility industry gets further involved in hydrogen production, it will assume additional markets in connection with chemical uses. A very sig- nificant such application would be in connection with coal gasification plants where use of an external source of hydrogen, such as from a nuclear plant using water as the hydrogen source, can result in significant savings of coal for the same yield of synthetic pipeline gas. Thus, utilities have the opportunity for PAGENO="0179" 173 participation in a new business area, the production of hydrogen for external sales in addition to internal fuel uses, before the end of this century. Long Range (Beyond 2000): In the longer range there are few ultimate energy sources; fission, fusion, solar, and (depending on resource extent) geothermal. Moreover, there appear to be only two long-term energy carriers; electricity and hydrogen. We are already beginning to realize that our irreplaceable hydrocarbon assets have value as chemical resources that far exceed their worth as simple fuels. Hydrogen and electricity in the long term can serve complementary roles in fulfilling energy markets. As energy carriers, each has specific applications for which it is the best and most cost-effective choice. Between them, most if not all future end users of energy can be satisfied. The challenge is for the electric utilities to recognize their future as Ene~y~ Utilities, potential suppliers of both electricity and hydrogen. We would like to submit for the record a paper in which the long-range possibilities of hydrogen for the electric utilities are discussed at greater length. It appears as Appen- dix C. ELECTRIC UTILITY INTEREST IN HYDROGEN--WRY? Today's electric utility is concerned with securing primary energy resources, con- verting them into a conveniently transported and utilized synthetic energy form (electricity), distributing the energy to the customer in a configuration opti- mized to his needs, and ultimately monitoring consumption and billing the energy PAGENO="0180" 174 user. If another synthetic energy form (hydrogen), also derivable from primary energy sources, easily transported and consumed and easily converted to and from electricity, were identified, it would be a logical extension of the utility in- dustry's present activities to include the production, distribution, and sale of this second product alongside these identical roles with respect to electricity. Hydrogen may well become the product transmitted from certain energy generation concepts such as solar, wind, or ocean thermal gradient schemes, or applications of conventional forms of generation such as remote nuclear parks. The nuclear and solar power sources that are expected to provide primary energy for the Hydrogen-Electric Economy are all characterized by small or absent fuel costs and high capital costs. This economic fact of life will define the fiscal structure of any company that hopes to earn a return on investment by selling hydrogen. Today the electric utility industry is by far the most heavily capi- talized industry. Gas, oil, and coal companies are basically distributors of bulk materials. Their product is, in many cases, delivered in essentially the same form as when it left the original source. Electric utilities, as noted above, sell synthetic energy. They have considerable operating experience in treating the raw energy of flowing water, coal, oil, gas, and the atom and optimizing con- version and delivery processes with the consumer, stockholder, and government regulator in mind. Given an appropriate regulatory climate, the growth of electric utilities into energy utilities, which would supply both hydrogen and electricity, may be an attractive possibility. A possible combination might be to utilize the strength of the electric utilities in ownership of large-scale energy conversion devices with the gas utilities' expertise in transmission and distribution of gaseous energy. With both hydrogen and electricity in the delivery system, energy storage PAGENO="0181" 175 should come much more naturally than it does in an all-electric system. Moreover, transformation from electricity to hydrogen and back again using fuel cells and electrolytic devices can be easily accomplished where warranted in order to meet peak demands for either energy form. Thinking of the long-range future, and assuming economic methods of production are developed, it is instructive to examine some of the more apparent effects upon energy system reliability and economics when hydrogen and/or electricity locally produced from hydrogen is delivered to the customer. Since the energy delivery system is underground, most outages associated with weather problems would not exist. Current low utilization factors on electrical generation and transmission equipment could be increased substantially, reducing overall costs. Energy storage comes automatically with hydrogen pipelines by varying pressure in the pipelines. Even a small amount of such storage combined with fuel cell power plants should significantly reduce the cost of maintaining the level of instantaneous reliability that our customers presently enjoy. These and other technical issues are discussed more' completely in the attached Appendix C.. IMPORTANT RESEARCH AREAS: I will now address the research areas that we feel will be important from a utility perspective. C~neratiOn: Obviously, research on hydrogen production techniques, using nonfossil energy sources, should command a top priority. The development of advanced electrolyzers, having increased efficiency relative to existing units, would have a significant impact on PAGENO="0182" 176 the near- and intermediate-term production of hydrogen for premium uses. The thermo- chemical technique for generation of hydrogen offers the potential for still higher efficiencies and further cost reductions. This promise merits increased activity in the area of thermochemical cycle discovery and chemical engineering analysis in order to better predict production efficiencies and costs. Hydrogen produced from coal may be an important option during the transition from the fossil to renewable energy economies, and deserves further examination. Other techniques for hydrogen generation such as photolysis, direct thermal dissociation, and production using biological means, are principally of longer term interest. Transmission: Although some experience exists in the handling and transmission of hydrogen, a considerable amount of work will be required to make this technology generally applicable to large hydrogen transmission networks and use by the general public. Other key questions include determining the extent to which existing natural gas pipelines need to be upgraded in order to handle hydrogen, and what, if any, special precautions will be required to insure employee and public safety. Storagg~ While it has not been established that hydrogen storage holds advantages over other proposed and existing techniques for near-term storage of energy on an elec- tric utility system, storage concepts such as liquid hydrogen, metal hydrides, and so forth, will play an essential role in almost all activities contemplated within the hydrogen systems concept. Advances in electrolyzer, fuel cell, and hydrogen storage areas could, of course, make these technologies useful to electric utility grids as load leveling devices. PAGENO="0183" 177 Utilization: In the utilization area, the major questions are those associated with safety and with the technical problems in conversion from natural gas to hydrogen uses in the home and in industry. Development of hydrogen-oxygen and hydrogen-air fuel cells, catalytic burners, and other devices will, of course, be significant. Legal, Environmental, and Economic Issues: The resolution of the many legal issues associated with the massive change in energy systems from today's natural gas and petroleum dominated economy to tomorrow's combined hydrogen and electric economy will determine the ease with which this change can be made. While hydrogen is generally thought to be environmentally benign, environmental issues associated with all phases of hydrogen energy systems need careful and continuous evaluation. In the economic area, the key question will be whether hydrogen will compete via the actions of the marketplace in increasing the price of alternatives, or by direct governmentai, tncentives for conservation of fossil supplies. The danger is that the market price of fossil fuels will be low enough over the next few decades to preclude substitution by synthetic fuels. This would result in rapid resource depletion and a delayed, but more difficult, transition to nondepletable energy sources. CONCLUSIONS: Our fossil resources are, of course, finite; renewable sources of energy must eventually be brought to bear to feed an economy and society that is becoming increasingly energy intensive. To meet all our needs, synthetic energy forms in addition to electricity will certainly be needed. Hydrogen and hydrogen-rich PAGENO="0184" 178 fuels, such as methanol or ammonia, have chemical and physical properties that make them excellent candidates for such application. The arguments raised in opposition to the development of hydrogen energy systems are those of efficiency and cost. Efficiency will, of course, become less of a factor with utilization of the virtually infinite nuclear and solar energy resources. The cost argument will fall with the rising costs of alternative energy sources and with the reali- zation that our fossil resources are far too limited and too valuable to burn. At Northeast Utilities we have a substantial commitment to further investigate hydrogen energy systems for our long-range future. It is our belief that hydrogen production facilities may become important consumers of electricity within a time scale not much longer than that of present utility planning and in the long run hydrogen, as an energy carrier,may well be as important to our industry as electricity. We shall be happy to answer any questions. PAGENO="0185" 179 Appendix A BIOGRAPHY SIDNEY H. LAW DIRECTOR - RESEARCH A graduate of Cornell University, Mr. Law received his bachelor of electrical engineering degree in 1948. He has also attended the U. S. Air Force Meteor- ology School at MIT and has completed the Public Utility Executive Program at the University of Michigan and the Power Systems Engineering course at General Electric. Mr. Law began his utility career with Western Massachusetts Electric Company in 1948 as an engineer in system planning. He became protection engineer in 1956 and system planning engineer two years later. In 1961 he was named senior super- vising engineer and transferred to Northeast Utilities Service Company as research engineer in 1966. He became director of technical research in 1967. Prior to the formation of the Electric Power Research Institute, he was a member of the Edison Electric Institute's Committee on Advanced Developments and was Chairman of its Electrochemical and Energy Storage Task Force. He was also a member of the Electric Research ~ Task Force on Secondary Batteries and a member of the ERC Underground Transmission Research Projects Steering Committee and Chairman of several of its subcommittees involved in Gas Dielectric Research. With the formation of EPRI, Mr. Law became a member of its Fossil Fuel and Ad- vanced Systems Divisional Committee and Chairman of its Electrochemical Energy Conversion and Storage Program Committee. He is the Company's representative to the "TARGET" fuel cell research program, and a member of the Steering Committees for the FCG-l Electric Utility Fuel Cell Research Program and Chairman of its Technical Subcommittee. He was also a member of several of the FPC Task Forces charged with preparing parts of the 1974 National Power Survey. He is a member of the IEEE Energy Develop- ment Committee and is a former chairman of the Springfield Section of IEEE. He served with the U. S. Air Corps from 1943 to 1946, rising to the rank of first lieutenant in the Weather Service. PAGENO="0186" 180 Appendix B MICHAEL LOTKER SCIENTIST ADVANCED ENERGY CONVERSION RESEARCH Mr. Lotker received his bachelor's degree in Physics from Queens College of The City University of New York in 1970, graduating Magna Cuts Laude, and with The Physics Prize. He received his M.S. from the University of Illinois in 1972. As a student he participated in research programs at Brookhaven and Argonne National Laboratories, principally in the area of superconductivity. As Scientist responsible for Advanced Energy Conversion Research, Mr. Lotker super- vises Northeast Utilities' activities in Hydrogen Energy Systems, Fusion, Solar, Geothermal, and other advanced concepts. He serves on several Electric Power Research Institute committees including its Advanced System Task Force, and is Chairman of EPRI working groups in fusion and solar energy areas. In addition, he is a member of the IEEE Standing Technical Committee on Fusion Technology and the Brookhaven National LaboratorY Utility Coordinating Committee which advises the BNL hydrogen energy storage and production work. He has authored a number of technical publications and reports in the solar, fusion, and hydrogen areas. Mr. Lotker is a member of Phi Beta Kappa and the American Association for the Advancement of Science. PAGENO="0187" 181 Appendix C HYDROGEN FOR THE ELECTRIC UTILITIES LONG RANGE POSSIBILITIES Michael Lotker Associate Research Physicist Northeast Utilities Hartford, Connecticut Presented at the 9th Intersociety Energy Conversion Engineering Conference August, 1974 PAGENO="0188" 182 HYDROGEN FOR THE ELECTRIC UTILITIES - LONG RANGE POSSIBILITIES Michael Lotker Northeast Utilities Hartford, Connecticut ABSTRACT The "hydrogen economy", a concept in which abundant prinary energy resources are converted into a synthet- ic forn, hydrogen, to be distributed throughout the energy market, is attracting increased attention as part of an optimal solution to the problems of energy supply. While substantial thought and research is go- ing into the concept's technological challenges, lit- tle effort has been spent examining the institutional considerations that will be crucial to industries con- tenplating activity in this area. In this paper the hydrogen economy is examined as a possible business area for the electric utilities in the long tern. Specifically, it is seen as a logical extension of this industry's production, transmission and sales of another synthetic energy form, electricity. The advantages and problems of such a "hydrogen-electric economy" are considered. INTRODUCTION Electric utilities have always been in the business of planning for the future. Today, when an electric company decides to construct a nuclear plant, the ten-year lead tine means that it is actually making a financial cononitment through the year 2014. A long term consideration for fuel availability over the life of a proposed plant, is already a factor in the increased orders for nuclear reactors. Even longer tern considerations, such as the eventual depletion of fossil and fissile (11235) energy resources has stimulated utility sponsored research on fast breeder reactors, fusion and solar energy in order to provide primary energy sources suffi- cient to give thousands, millions, or even billions of years of environmentally and economically sound service. Many authors, including those at this ses- sion on "Hydrogen Energy Systems," have recognized that such energy resources can serve virtually all the needs of society if they produce hydrogen in addition to electricity. The electric utilities may need to expand their activities and become "energy utilities" supplying both energy forms in order to best serve their customers' requirements. Below we examine the long-range (beyond the year 2000) possibilities for hydrogen in the electric utility industry. We shall see that the industry's present technical and financial structure makes it uniquely qualified to meet the demands of the hydro- gen economy and that hydrogen holds several attrac- tiona for the industry in fulfilling its charter with the public to provide reliable, inexpensive and clean energy. Possible obstacles to utility venture in this area are also discussed. A LOGICAL EXTENSION Han's earliest uses of energy were limited by his own metabolism and that of the animals he do- mesticated. The energy source was food and primary application motive power. Use of fire for warmth, cooking, and as a weapon opened up the multitude of ways that energy could be used and misused. Never- theless, it represented a singular developmental ad- vance for humanity. The energy source was a variety of organic materials and the applications limited to the obvious thermal annd optical properties of fire. Water power, tapped in the first century, B.C., served as the prime mover for the industrial revo- lution in western Europe while use of wind power, first appearing in the 12th century, was more lim- ited in its scope.3 The energy source for water power was site limited and variations in local weather limited wind power to intermittent opera- tion. The development of the steam engine freed man from such limitations on his prime mover and represented the first significant use of energy conversion, namely fuel to heat to mechanical energy. All of these early uses of energy suffered the same basic limitation; the point of energy genera- tion was necessarily the point of energy consumption. About one hundred years ago, the commercial generation of a synthetic energy form was accom- plished. Electric energy was the first energy form which could be remotely consumed, freeing the user from the technical and financial burden of own- ing and maintaining his own prime mover. As utility companies grew, the economies of scale and of load diversity actually allowed electricity costs to de- crease 8teadily. Subsequent developments identified uses for electricity that could not be net by other energy forms. Furthermore, electrical energy could now serve as energy's common denominator, allowing man to make use of almost any energy resosrce for much of his energy needs. Today's electric utility is concerned with se- curing primary energy resources, converting them into a conveniently transported and utilized synthetic energy form, distributing the energy to the customer in a configuration optimized to his needs, and ultimately monitoring consumption and billing the energy user (Figure 1). If another synthetic energy form, also derivable from primary energy sources, easily transported and consumed, were identified, it would be a logical extension of the utility industry's present activities to include the production, dis- tribution, and sales of this second product alongside these identical roles with respect to electricity. As many others have noted, hydrogen nay indeed be PAGENO="0189" this second product with a potential market even wider than that presently served by electricity (Figure 2). 183 THE INDUSTRY'S CAPABILITIES The nuclear and solar power sources that are expected to provide primary energy for the hydrogen economy are all characterized by small or absent fuel costs and high capital coats. This economic fact of life will define the fiscal structure of any company that hopes to earn a return on investment by selling hydrogen. Today the electric utility industry routinely amortizes its plant over some 30 years and up to an much as 75 years for hydroelectric installa- tions. It is the most heavily capitalized industry in this country by a substantial margin. For example, the estimated capital spending by the electric utilities in 1973 was $16.25 billion as compared to $5.41 billion for the petroleum industry and $2.84 billion for the gas industry (the total for all business was $100.08 billio,č 2 This in spite of the fact that the gas and petroleum in- dustries presently supply more energy to their customers than do the electric utilities. Gas companies are basically transporters of energy. Their product is delivered in essentially the same form as when it left the well. The early initiatives to produce synthetic gus from coal will begin to test this industry's capabilities in energy conversion. The petroleum industry is principally a bulk supplier of raw materials, albeit heavily refined in most in- stances. Electric companies, as noted above, sell synthetic energy. They have considerable operating. experience in treating the raw energy of flowing water, coal, oil, gas and the atom and optimizing conversion and delivery processes with the consumer, stockholder, and government regulator in mind. This expertise will be especially important in the nu- clear area which promises to play a significant role in the developing hydrogen-electric economy. POSSIBLE ROADBLOCKS The moat obvious obstacle to the electric industry expanding its role to include hydrogen production and males in the likely public and political objec- tion to increasing the scope of the monopoly under which these companies presently operate. Combina- tion gas amd electric companies would doubtlessly have an easier time making the transition but even they may have problems in serving synthetic chemical and transportation markets. Indeed, recent public and legal indications would prumise a tendency toward reduction and not increase in both vertically and horizontally integrated energy companies. It is ex- pected that the protection provided the public by state and federal regulatory bodies combined with the advantages of an early introduction of hydrogen into the energy market will overcome the apparent legal obstacles. An encouraging note in this di- rection was sounded by Professor of Law, T. C. Cady, who noted that "the (energy) law is flexible and can be readily adjusted.. .into a Hydrogen Economy."3 The electric utilities will be only one of several industries which may wish to go into the hydrogen business. The gas industry has a large stake in this technology which will grow as the domestic supply of natural gas diminishes. A large fraction of their experience, expertise, and capital plant may be directly applicable or convertible to hydrogen. The orderly transition from natural gas to hydrogen will be difficult, if not impossible, without the active cooperation of the gas industry. An optimal solution to this potential conflict may be to combine the strength of the electric companies in ownership of large scale energy conversion devices with the gas companies' strength in transmission and distribu- tion of gaseous energy. In such a configuration the electric utility would own and operate the means of hydrogen generation and sell the product in bulk to gas (or other) companies not unlike the manner in which the Tennessee Valley Authority sells bulk electric power to distribution companies. The capital requirements of a hydrogen based en- ergy economy are truly staggering. For example, to meet one-half the estimated shortfall in the demand for natural gas in the year 2000 with electrolytic hydrogen would require some 350,000 NIle of nuclear power plants and electrolyzers costing roughly $250 billion. Utilities are presently having pro- blems raising enough capital to suupport their pre- sent electrical expansion plans; the added burden of hydrogen generation facilities will be considerable. Federal and state authorities may for security and balance of trade reasons encourage hydrogen production and consumption in several ways. Pre- sently the expenses incurred during construction of an electrical generating plant are not applied to a company's rate base until the plant is actual- ly generating electricity. The result is that the interest on the funds during construction becomes part of the total capitalization of the plant. This amount can be in excess of one-third of the direct costs of a nuclear plant.4 An adjustment by the state regulatory commissions to include costs as incurred would reduce the overall capitalization of such plants. In addition, federal, state, or even local governments could substantially ease the pro- blem of obtaining capital and reduce the cost of hydrogen by providing tax exempt status to bonds issued for hydrogen production facilities. Other forces of tax relief, i.e. from property taxes and point of consumption (gasoline, sales) taxes would serve to smooth the transition from more conven- tiomal fuels to hydrogen until the latter became more economically competitive. THE ENERGY UTILITY A great lesson to be learned from the emerging energy crisis is the importance of a system treat- ment of energy related matters. As we have seen, shortages of one energy form will have direct and indirect impacts throughout the entire economy. Electric utilities, large consumers and sellers of energy in all forms, have been especially sensitized to this fact. In the past, a strong motivation for the existance of combination gas and electric com- panies was the expectation that the utility would serve the energy needs of his customer in an opti- mal way. These advantages will be expanded if hy- drogen, with its wide spectrum of uses, is delivered in combination with electricity. The two energy forms can serve virtually all the energy needs of indus- trial, connnercial, and residential customers. Fur- thermore, since hydrogen and electricity are easily and efficiently interconverted using electrolyzers PAGENO="0190" 184 and fuel cells, the energy utility would have con- siderably expanded operational flexibility. An extremely appealing advantage for the utili- ties (and, through regulatory control, the public) of a developed hydrogen-electric economy will be to stabilize the economics of energy supply. Primary resources for fission, fusion, and solar energy are all domestically available in an abundance suffi- cient to remove the impact of international politics. Perhaps less obvious, but significant too, will be the stabilizing effect of broadening the business base of the utility. As changes in energy consump- tion patterns occur, a company tied to but one energy form or to a limited customer category may face severe economic displacements. These changes pro- nine no such problems for the energy utility, which now has no economic barrier to encourage the wisest energy use for all segments of the energy market. The economies of scale associated with such an ex- panded business base should also translate into eco- nomic savings for the ultimate consumer. Energy storage is an area of no small importance to an electric utility. As other authors at this session detail,5'6 the conversion of electricity to hydrogen during off-peak bases for eventual recon- version during periods of maximum demand may be the industry's first step into the hydrogen field. Later on with a fully developed hydrogen-electric economy, energy storage becomes an element of almost every subsystem. Furthermore, the incremental costs associated with such storage may well be limited to the hydrogen handling facilities themselves since the energy conversion devices will have already bees installed. Storage can be distributed to make opti- mal use of both generation and transmission capaci- ties, ninimizing the total amount of either. One of the most basic technical constraints on an electric utility system stems from the fact that its pro- duct must be produced almost simultaneously with its remote, uncontrolled consumption. By generating hydrogen as an energy transmission medium this con- straint disappears. It is instructive to examine some of the more apparent effects upon system reli- ability and economics when hydrogen and/or electri- city locally produced from hydrogen, is delivered to the customer. - Since the energy delivery system is under- ground, the more severe outages associated with weather problems simply would not exist. - The current low utilization factor on elec- tric transmission lines (about 30 percent) is as much a- reflection of the necessity for redundancy as well as the hourly and seasonal variations in load. Hydrogen and hydrogen pipelines would increase this utilization factor, hence reduce overall energy transmission costs, by decreasing the need for redundancy and increasing the load factor via energy storage at the cus- tomer end of the pipeline. - A gas system is not subject to the delicate system stability difficulties that a modern AC transmission grid may incur. A major problem in a gas system would propagate at or less then the speed of sound. Corrective diagnosis and control of such a problem (pressure and temperature sensors, valves, etc.) can be electrically accomplished at speeds approaching the speed of light. This should provide for a relatively straight- forward technique for system protection. On an electrical grid, however, protective devices that operate on the millisecond timescale are required to prevent the rest of the system from becoming unstable. - In today's electric system, even a momen- tary failure in a generating plant can mean loss of service to customers unless additional power can be supplied immediately. In practice, this means that a system must have standby geseration or reserve sufficient to cover the loss of its largest unit plus some additional safety factor. Utilities nay, at times, have to resort to brownouts (volt- age reductions) or rotating blackouts to re- tain some measure of this reserve. If, however, the generating plant were separated from the customer by a high pressure hydrogen pipeline, short interruptions in generation (such as those associated with control problems in nuclear reactors) would not require reserve protection and more importantly would not affect the customer at all. - The electric system is currently character- ized by high reliability for each and every component; to do less would impose unaccept- able reserve criteria. Again, by the inser- tion of a gaseous "energy cushion" with surge capacity at both ends of the utility to cus- tomer link, the reliability consequences of momentary malfunction (with the exception of safety related failures) is minimized. This should, in principle, reduce the cost of such systems without sacrificing quality of - For these reasons, the reserve requirements for the hydrogen generators would be reduced, possibly in quantity, but almost certainly in the speed in which they must be brought on line relative to current electrical practice. Presently, some fraction of the electrical -reserve must be available within five minutes, with the remainder available within 30 minutes to an hour, With a pipe- line system, the natural storage provided by the volume and pressure of the contained gas may well serve as a large fraction of the reserve needed to insure reliability. The alternative to expanding the energy delivery system to include a synthetic fuel such as hydrogen is to consider a strictly electrical expansion which would make use of our nuclear and solar energy resources. The problem in supplying electrical transmission in future decades will be staggering when one considers the difficulties presently escountered by utilities in installing needed over- head lines in populated or scenic areas. Technolog- ical and environmental limitations on the maximum voltage of such lines will mean that the need for new and expanded rights-of-way will lag not far behind load growth. Underground cable, including superconducting and DC technologies, will almost certainly be required with their attendant high costs and operational difficulties. There will PAGENO="0191" 185 still be energy need8 which cannot be fulfilled by electricity and which can, in the absence of fossil fuels, be adequately met by hydrogen. CONCLUSION As the fossil age draws to a close, society will have to make widespread use of synthetic energy forms to neet its varied energy needs. Electricity, the first of such forms, will almost certainly be joined by hydrogen to meet the energy markets in the future. The present electric utility induAtry is seen to have the technical and financial capabilities along with considerable incentives to act as the institu- tional basis for hydrogen production, transmission, and sales in conjunction with these identical roles regarding electricity. REFERENCES (1) C. Starr, "Energy and Power," Scientific American, vol. 225, pp. 37-49, Sept. 1971. (2) "Energy Crunch Hikes Capital Spending," Electrical World, vol. 181, pg. 11, April 1, 1974. (3) T. C. Cady, "The Hydrogen Economy and the Law," Procedings of The Hydrogen Economy Miami Energy (THENE) Conference, pp. Sl5-l7 to S15-35, March 1974. (4) A. U. Little Inc., "Study of Base Load Alter- natives for the Northeast Utilities System, pp. 73-75, July 1973. (5) R. Fernandes, "Hydrogen Cycle Peak Shaving for Electric Utilities," (this conference). (6) J. N. Burger et al., "Energy Storage for Utilities Via Hydrogen Systems," (this conference). PAGENO="0192" 2 -4 m I- m -~ r -4 -C PAGENO="0193" 187 Hydrogen As An Electric Utility Fuel Ira Thierer Associate Director of Research and Development Southern California Edison Company Rosemead, California And Michael Lotker Assistant Research Physicist Northeast Utilities Service Company Hartford, Connecticut 62-332 0 - 76 - 13 PAGENO="0194" 188 INTRODUCTION Today's electric utility is in the business of energy conversion ~and distribution. It transforms primary energy sources, such as coal, oil, natural gas, uranium, and flowing water into electricity, a more convenient energy form. In this way, the consumer can use nuclear energy to light his home, coal to run his computers, and flowing water to power rail transportation. Electricity is, then, a synthetic energy form with properties sufficiently desirable to warrant the expense and inefficiencies associated with its production. If another synthetic energy form, also easily transportable, and producible from primary energy resources is recognized, it would then 1~e a logical extension for the electric utility industry to expand its traditional roles of production, transmission, distribution, and sales to include this new energy form, assuming, of course, that the new form offered features which allowed it to fill needs not otherwise readily satisfied. Such needs do exist. There is, for example, a need for a synthetic energy form which can be transported cheaply by methods having minimal visible impact. There is also a need for synthetic energy forms which can be stored, so that maximum use can be made of primary generation facilities. Coupled with the prospects of dwindling oil and natural gas supplies in the future, the potential ability of hydrogen to fill these needs is the motivation for electric utility interest in hydrogen as a fuel. PAGENO="0195" 189 The Hydrogen Economy With appropriate storage and transmission, hydrogen has applica- tion in almost every sector of the energy market, as indicated in Figure 1. Hydrogen can be substituted for natural gas in domestic and industrial space heating, and since the only combustion product is water vapor, the need for a flue may be eliminated and only dehumidification required. This would increase the efficiency of furnaces and allow for individual room controls as is the case today with electric heat alone. Hydrogen also has large potential markets as a chemical in the production of other chemicals, and in petroleum refining. In the transportation sector, hydrogen fueled automobile and aircraft operation has already been successfully demonstrated)-,2 Here, the major technical challenge will be storage, with either metal hydrides3 or liquid hydrogen as possible options. In regard to electric energy, hydrogen fuel could be converted to electricity via fuel cells, devices which produce electricity directly fran chemical energy at efficiencies up to about 55 percent. Even more efficient conversion of hydrogen to electricity may be possible with high temperature hydrogen-oxygen combustors. Hydrogen could, in principle, also be used to store energy for an electric system in a manner analogous to pumped hydroelectric energy storage.4 Safety An examination of hydrogen's chemical properties indicates that it is about as safe as natural gas (methane). While a hydrogen-oxygen mixture ha~ wider flammability limits than does a methane-oxygen PAGENO="0196" 190 LOCAL POWER STATIONS UNDERGROUND HYDROGEN ________ TRANSMISSION LIQUID ~ ~ HYDROGEN AND REDUCING GAS IND(ISTRIAL FUEL ELECTROLYZER STORAGE LARGE ______________ NUCLEAR AND LIQUID FUELS STATION POWER UNDERGROU HYDROGEN _______ ______ ~ TRANSPORTATION Figure 1. Hydrogen in the Energy Market PAGENO="0197" 191 mixture, the more significant lower limits are comparable. Although hydrogen leaks more rapidly due to its smaller molecular size and mass, it has less energy content per unit volume and disperses more rapidly. Hydrogen, like methane, is odorless and will probably require an artificial odorant. In addition, it burns with an invisible flame, an advantage in that it would reduce radiative heat damage during a major fire, but may create a possible hazard for home use, where an additive to make the flame visible may be necessary. The space program has demonstrated that large quantities of hydrogen can be handled safely over a period of years. Present Status The previous discussions represent a crystalization of current thinking which envisions a "hydrogen economy", as a unified energy system revolving around the fuel, hydrogen. The potential advantages of a "hydrogen economy" have been thoroughly explored.5 Some elements of the hydrogen economy,as it is currently envisioned, may displace present-day practices relatively rapidly. Others may evolve more slowly or perhaps be set aside in favor of economically preferable approaehes. Regardless, the gap between the realization of the long range hydrogen economy and the present-day hydrogen utilization is striking. The annual world production of hydrogen stands at three trillion standard cubic feet. This amount would roughly satisfy the present-day annual fuel needs of only a single large Mnerican electric utility. Most of the world production is accomplished by reforming PAGENO="0198" 192 natural gas or naphtha; roughly three percent is obtained by electrolysis, primarily in countries with substantial hydroelectric resources. The American space effort consumes a large share of the world production. The average cost of liquid hydrogen used by NASA is nearly $4/N Btu, which exceeds by a substantial margin the average $/Btu cost of fuels currently used by electric utilities. Note that $4/N Btu is roughly equivalent to oil at $24/barrel. Production Considerations The cost mentioned above perhaps only reflects present-day small scale production operations, but it nevertheless represents a major obstacle to introduction of hydrogen into the emergy market. Moreover, it is apparent that the "hydrogen economy", if it expands as envisioned, cannot continue to be based on conversion of liquid fuels or natural gas, the long term availability of which is not assured. UnEortunately, hydrogen derived from other primary energy sources will similarly have high costs, for reasons to be discussed. Hydrogen, unlike fossil fuels, is not naturally available except as a constituent of other materials. Because it readily reduces other elements, it resides in compounds, notably water (H20), and fossil fuels such as methane (CH4). These compounds arevery stable; it is necessary to supply energy to break them apart to release their * store of hydrogen. For example, in the case of water the entire heat of combustion of the hydrogen, plus process losses, must be supplied. Thus, the cost of the hydrogen produced must be reckoned in terms of botha primary energy cost and a cost associated with equipment in PAGENO="0199" 193 which the conversion process takes place. Primary energy can be supplied as heat or electricity, or both, and it is easily demonstrated that the cost of primary energy will dominate cost comparisons among major alternatives. For example, if hydrogen were to be produced by electrolysis using electricity from a nuclear plant constructed in the mid-l970's, the energy cost alone would be more than $5/M Btu, or roughly 9O7~ of the total cost of production. Alternatives to Electrolysis There are several alternatives to electrolysis to fulfill future demands for hydrogen. For example, it is possible that biological processes may eventually be employed. Bacteria obtait~ energy for growth through a series of dehydrogenation or coupled oxidation- reduction reactions. Certain organisms have the ability to form hydrogen (~ gas or methane in the dehydrogenation process. By proper manipulation of culture conditions it may be possible to derive either CH4 or H2 from organic matter. In the foreseeable future, processes for production of hydrogen directly from coal or nuclear heat represent the major alternatives to electrolysis. In these cases the utilization of primary energy resources could, at least in principle, be more efficient than in the case of electrolysis. There is some uncertainty as to the extent of economically recoverable nuclear ores and coal reserves, but most estimates of the number of years to deplete these resources are con- sistent with the view that ample time remains to develop economically PAGENO="0200" 194 feasible means of tapping the virtually inexhaustible energy resources (solar, fusion, and geothermal) for hydrogen production. Role of Electric Utilities In moving toward a "hydrogen economy", what appears to be needed at this time is a first step toward large scale production and non- specialty use of hydrogen. Electric utilities may play a key role in determining when and how, and perhaps whether, this first step is to be taken. For example, possible utility uses for hydrogen may appear within the next decade as a result of current investigations into the fuelcell as a peaking and intermediate load device. Avenues from hydrogen production to electricity generation whiFh involve fuel cells as users and fossil fuels as a source may be the most feasible in the near future. These avenues are highlighted in Figure 2, which is a schematic representation of the part of overall hydrogen economy that is of special interest to electric utilities. The fuels for the first generation of fuel cell generators, number 2 oil or lighter grades, cost between $2.50 and $3.00/M Btu in the current fuel squeeze. Although future costs for these fuels are highly uncertain, it is significant to note that the primary energy costs for deriving hydrogen from coal and from a nuclear thermochemical cycle appear to be in this same general range or below. HYDROGEN PRODUCTION This section briefly analyzes the major production options identified in the above section, including electrolytic and thermo- chemical processes, and conversion of coal to hydrogen or hydrogen PAGENO="0201" PRIMARY ENERGY DIRECT PRODUCT ALTERNATE PRODUCT SPECIAL PROCESS HYDROGEN SOURCE TRANSMISSION DISTRIBUTION STORAGE CONVERSION DEVICES NEAR TERM LATER 195 Figure 2. Avenues from Hydrogen Production to Electricity Generation PAGENO="0202" 196 rich gases. The desirability of an energy system based on hydrogen will be strongly influenced by the production system, its cost, its environ- mental impact, and its ability to make effective use of primary energy resources. In our analysis of production processes, we attempt to place the qualitative advantages of each process in perspective by comparing its primary energy cost to those of alternative processes. Electrolysis Hydrogen may be produced directly from water by passage of an electrical current through an electrolysis cell. In an ideal electrolyzer, part of the energy (about 177.) required to break down'water may be supplied from ambient heat, with the remainder supplied electrically. Thus, such an electrolyzer would have an "efficiency" (defined as hydrogen's higher heating value divided by electrical energy input) of 1207.. Today's electrolyzers have substantially reduced efficiencies of 6O-7O7.~, while advanced cell designs promise efficiencies of about 907. in the early 1980's, and goals of 1007. or more do not seem un- reasonable.6 A recent study7 analyzed costs for an electrolyzer capable of supplying hydrogen to 1000 NW of 507. efficient fuel cells. Hydrogen generated at a rate of 21,000,000 ft3/h resulted in a water demand (for decomposition) of almost 2000 gal/mm. The capital cost of the plant, approximately $175,000,000, resulted in an incremental cost of about $0.60/N Btu above energy costs. Starting from this figure, PAGENO="0203" 197 hydrogen costs then increase almost linearly with the cost of electric power. With electric costs of $.015/kWh, which is typical of expected generation costs for reactors coming on line in the mid or late 1970's, the cost of primary energy for hydrogen production by electrolysis is in excess of $5/N Btu, while the total production cost is on the order of $6/N Btu. Use of Off-Peak Power for Electrolysis It has been suggested that electrolytic hydrogen might be inexpensively generated using off-peak nuclear power, assigning to the production process only the fuel costs (about $0.002/kWh) and excluding all capital charges from the cost of input electricity. Implicit in this suggestion is the assumption that the nuclear plant would not be required to meet the system's nighttime base loads and that no other potential load such as pumping water or charging batteries was available. Such a situation would occur only as a result of improper utility planning. In the event that the utility installed the nuclear plant with the intention of using it off-peak to produce hydrogen for external sales, it would have to assign the capital carrying charges of the plant to the cost of hydrogen on an equitable basis in order to keep the cost of electricity generated by that plant reasonable. In generating hydrogen for its own uses however, a utility might have more flexibility. For example, it is presently economical to store a small fraction of a utility's total energy output in pumped hydroelectric installations for later use in meeting peak loads. PAGENO="0204" 198 Similarly, electrolytically generated hydrogen could be used to store energy for later conversion in a fuel cell or as a supplement to natural gas supplies (for a combination electric and gas company) if the total cost of meeting the company's load were thereby reduced. It should be emphasized that these options, while significant first steps, would not result in the introduction of hydrogen on the massive.scale contemplated in the "hydrogen economy" concept. Thermochemical Production At room temperature, more than 807. of the requisite enthalpy change involved in separating the hydrogen and oxygen found in water must be produced by supplying useful work, as in the qlectrolysis cell. Alternatively, it is possible to operate a sequence of chemical steps with no net work requirements (i.e. only heat) at temperatures around 1000°F, which are well below the range of temperatures required to achieve appreciable thermal dissociation of water (i.e. above 4500°F). In the electrolysis process, the amount of electricity needed is equal to the free energy of water. If the energy supplied is heat rather than electricity, the efficiency of converting primary heat to the heat of combustion of hydrogen is subject to a limit which reflects the laws of thermodynamics and is exactly analogous to the Carnot limit which applies to all thermal conversion processes. Many thermochemical cycles have been proposed. The actual overall efficiencies of the practical cycles that are the goal of the current PAGENO="0205" 199 cycle searches may be 2O-5O7~, based on hydrogen's lower heating value.8 It is possible to compute a basic cost for the energy consumed in a thermochemical hydrogen production plant. Assuming that the cost of supplying nuclear or solar heat would account for about two thirds of the total cost of electricity, the $O.0l5/kWh assumed previously implies a thermal energy cost for hydrogen production of about $O.0033 per thermal kWh supplied. Assuming thermochemical cycle efficiencies of 5O7~, the resulting cost of energy for thermochemical hydrogen production would be in excess of $2/N Btu. If the chemical process equipment were to cost no more than the boiler and turbine-generator portion of a nuclear plant, and had an identical effect on plant availability, our assumptions imply that the total cost of hydrogen production by this method would be slightly in excess of $3/N Btu. However, there are indications that the cycle selection process will settle on a four-step cycle, based on a trade-off between decreased cycle complexity as steps are eliminated, and increased possibilities for substituting heat for work as steps are added. Unfortunately, cycles with even as few as two or three steps would pose severe high temperature chemical engineering problems, and the reasonable requirement that chemicals be recycled imposes capital cost and substantial energy loss penalties associated with chemical separation processes. Accordingly, the cost figures derived above are believed to represent minimal rather than nominal costs. PAGENO="0206" 200 Coal Conversion It has been estimated in numerous reports that the U.S. has sufficient ultimately discoverable coal to fill its projected fuel needs for the order of one hundred to five hundred years. Therefore, it is logical to view coal as a potential interim or even long range source of hydrogen. When steam, at 1800°F, reacts with coal, the products are C02, CO, H2 and CH4. The ratio of H2 to CH4 depends on the steam pressure; CH4 is produced in small amounts at 450 psi and becomes a significant product at 1000 psi. The coal-steam reaction is endothermic; a source of heat must be provided. For example, heat can be made available by supplying additional coal and adding pure oxygen to the steam to react with (burn) the additional coal. The coal-oxygen reaction produces additional CO and C02; CO from both reactions is caused to react with additional steam to produce CO2 and more hydrogen. CO2 is removed by scrubbing, and the final hydrogen can be 97-98 percent pure. Using this method, 5.2 lbs. of oxygen, 8.7 lbs. of coal and 8.8 lbs. of steam are required to produce 1 lb. of H2.9 We can compute an energy cost for H2 from coal that may be compared with the costs computed previously for thermochemical and electrolytic processes. The lower heating value of 8.7 lbs. of bituminous coal is~ in excess of 100,000 Btu, while the lower heating value of 1 lb. of H2 is roughly 50,000 Btu, which implies a "coal conversion efficiency" of around 507~ or less. Thus the cost of coal or "energy" for the PAGENO="0207" 201 production of hydrogen from coal would be roughly twice the $/Btu cost of the coal. If coal costs $O.40/M Btu, the energy cost for hydrogen production would be in excess of $O.80/M Btu. It appears that much of the technology for gasification of coal to produce methane will be adaptable to the production of hydrogen from coal. However, it should be noted that many factors favor methane over hydrogen as the direct product of the coal conversion process. While the "coal conversion efficiency" for hydrogen production would be around 5O7~, it would be around 65'L for methane. Less water is required for methane production, and the higher pressures of the methane production process reduce compression requirements associated with storage and distribution. SUMMARY AND CONCLUSIONS General We have attempted in this paper to analyze the idea of "a hydrogen economy" from an electric utility viewpoint, emphasizing near term possibilities. Clearly, there are many uses for cheap hydrogen, but at present, relatively large and economical production facilities do not exist. So, where do we start? A convenient place is within a system large enough to begin to both use and produce hydrogen on a significant scale without jeopardizing its ability to function. This description fits a large utility, and it is not surprising, therefore, that an extensive "hydrogen economy" may eventually rest on the foundation now being laid in the course of the utility fuel cell program. Within the space of a local substation will be facilities to both PAGENO="0208" 202 produce and use hydrogen. Assuming this first step is successful, the stage is set for a larger step involving major electric generating and production facilities. Having identified economical production as the key,. we discussed the major hydrogen production processes of the future and computed a cost associated with the basic energy source for each process. We deliberately omitted from consideration the possibility of reforming natural gas or petroleum derivatives to provide, hydrogen. These fuels are not considered reliable long-term alternative sources of hydrogen. Development of biological methods for production of hydrogen is in its infancy, and even rough cost estimates cannot be provided. Table I summarizes the results of cost estimates for processes described. TABLE I - ESTIMATED COSTS TO PROVIDE ENERGY FOR H2 PRODUCTION Process $/M Btu Electrolysis A? 5 Thermochemical ~ 2 Coal (@ $O.4O/M Btu) ~ 1 Although the cost of process equipment associated with coal conversion was neglected, so were the costs of functionally equivalent items associated with other processes. These costs, in principle, can be small relative to the "energy" costs that are tabulated. Evidently, until coal resources are substantially depleted, the most economical large scale processes for hydrogen production will be based on coal. Note, however, that we have computed only those costs associated with PAGENO="0209" 203 the supply of primary energy, and the costs listed should be taken merely as a rough indication of where major costs of hydrogen production may eventually fall. It appears that, even with a credit for the by-product oxygen, the cost of hydrogen by electrolytic or thermochemical processes is likely to be excessive for the foreseeable future. This picture could change with the success of some of the more exotic energy concepts such as solar farms, windmills, etc. Also, special situations may emerge early, in which electrolysis or thermochemical production technology now under development can be profitably applied. In the case of coal it appears that, at least in the near term, production of methane from coal may be favored over production of hydrogen for several reasons, including resource utilization efficiency. Perhaps more important, the use of methane requires no large-scale changeover in distribution and usage systems. In the case of end-use devices for which hydrogen is the preferred fuel, such as fuel cells, the methane could be reformed to produce hydrogen at the point of use. In the long term, advantages of using hydrogen in favor of methane, or where methane is not presently used, may compel the construction of production and distribution systems designed for hydrogen. R&D Needs It is difficult to escape the conclusion that, both on its own merits and because of its significance to production of hydrogen, coal gasification to methane and hydrogen should be assigned a high priority among items of energy R&D. Processes for large-scale 62-332 0 - 76 - 14 PAGENO="0210" 204 gasification of coal to methane may become an integral part of our national energy supply. Hydrogen can be produced by similar processes or by reforming the methane thus produced, as economics and convenience dictate. There is also much work to be done in the areas of thermochemical cycle and electrolyzer technology. Developments in these areas could have a major, but as yet unforeseeable, impact in the context of a large scale "hydrogen economy" which could ultimately develop in the future. From an electric utility point of view, development of electric generation equipment adaptable to,or designed for, hydrogen fuel may be an equally important need. If hydrogen is to become a significant fuel source for the near-term production of electricity, substantial efforts will be needed to develop turbines which can take advantage of the high temperature high pressure steam which can be produced by combining hydrogen and oxygen. Feasibility studies of converting conventional gas turbines and gas and oil fired boilers to burn hydrogen are needed as well, and the program to develop fuel cell generators suitable for utility use should, we feel, continue to be vigorously pursued. PAGENO="0211" 205 REFERENCES 1. R. G. Murray and R. J. Schoeppel, "Emission and Perforn~ance Characteristics of an Air Breathing Hydrogen Fired Internal Combustion Engine, "Paper No. 719009, Intersōciety Energy Conversion Engineering Conference Proceedings, August, 1971. 2. W. J. D. Escher, "Prospects for Liquid Hydrogen Fueled Commercial Aircraft," Escher Technology Associates Report PR-37, September, 1973. 3. K. C. Hoffman, et al., "Metal Hydrides as a Source of Fuel for Vehicular Propulsion," International Automotive Engineering Congress Paper 690232, Society of Automotive Engineers, January,, 1969. 4. F. J. Salzano, et al., "On the Role of Hydrogen in Electric Energy Storage," The Hydrogen Economy Miami Energy Conference (THEME), March, 1974. 5. D. P. Gregory, A Hydrogen-Energy System," Publication No. 121173, Institute of Gas Technology, Chicago, Illinois. 6. W. A. Titterington andA~. P. Pickett, "Electrolytic Hydrogen Fuel Production.with Solid Polymer Electrolyte Technology," Paper No. 739020, 8th Intersociety Energy Conversion Engineering Conference Proceedings, August, 1973. 7. E. Fein, and J. G. Stover, "Hydrogen: A Fuel for the Electric Utility," The Futures Group, Glastonbury, Connecticut, May, 1973. 8. R. L. Savage, ed., "A Hydrogen Energy Carrier," Summary of the Results of .the 1973 ASEE-NASA Summer Faculty Program; Volume II (Systems Analysis), September 1973. 9. Synthetic Fuels Panel, "Hydrogen and Other Synthetic Fuels," Summary of the work of the Synthetic Fuels Panel, prepared for the Federal Council on Science and Technology R&D Goals Study, September, 1972. PAGENO="0212" 206 Mr. MCCORMAOK. Please continue, Mr. Law. Mr. LAW. Thank you, Mr. Chairman. I disagree with Dr. Gregory in his somewhat pessimistic view of electricity, but I don't believe that is the purpose of this hearing, so we won't go into that. I am happy to appear before you today to discuss hydrogen energy systems from a utility perspective. I will limit my remarks to the utility point of view, since I am certain that other experts have ade- quately discussed the technical details and the broader implications of the so-called hydrogen economy. Since electricity is importantly involved in this view for our energy future. I prefer to call it the hydrogen-electric economy. I will refer to it this way in my testimony. I also want to point out that, while we have endeavored to examine this from a utility point of view, that the views reflected in the testi- mony are those of Northeast Utilities only. There is still no real consensus within our industry on the future or importance of such systems, although EPRI is currently evaluating them. As to Northeast Utilities' interest in hydrogen, let me say this. Northeast Utilities became interested in hydrogen energy systems through its participation in fuel cell research. Hydrogen is, of course, the ultimate fuel for fuel cells and can be easily piped to such power- plants, located in individual neighborhoods. thereby reducing depend- ence on transmission and increasing efficiency with minimum impact on the environment,. In 1972, we funded a study which assessed the hydro- gen-electric economy scenario in its entirety and concluded that there was indeed long-range promise in this concept. The study was followed up by a more narrowly defined consideration of the early application of hydrogen in connection with our proposed fuel cell work. Our continuing interest led us to formulate a program with Gen- eral Atomic Co. to identify and develop thermochemical cycles for generating hydrogen. Now, the goal of the program, which has received nearly $400,000 from our company to date, is to develop a technique for hydrogen pro- duction directly from nuclear heat at a greater efficiency and conse- quently at a lower cost than is possible with electrolysis. Our interest in hydrogen is, we feel, a logical extension of our re- sponsibilities in connection with electricity supply. Hydrogen, like electricity, is a synthetic energy medium or energy carrier. Both re- quire attention to the technology of generation, transmission, distribu- tion, and consumption by the ultimate user. ELEO~RIO t'HLITY INTEREST IN HYDROGEN-WHEN? I would now like to discuss how electric utility interest in hydrogen may develop in the future. I've divided the future into three time frames: short range (1975-85), intermediate range (1985-2000), and long range (beyond the year 2000). SHORT RANGE (1975-85) The only general use for hydrogen today in the electric utility is as a coola.nt for the windings in large electrical generators. Hydrogen will probably not be important as either an energy storage medium or as a PAGENO="0213" 207 fuel for electric utilities during the next 10 years (fuel cells, supplied by fossil fuels, could have an impact in this time frame however). I want to mention the immense importance that we feel the hydro- carbon fuel cell has to our industry in the next 10 to 15 years when the country must, whether it likes it or not, continue to use `large quantities of petroleum fuel for the generation of electricity. This device, which the electric and gas industry has spent over $100 million developing during the past 10 years, can reduce significantly the amount of this fuel used for intermediate and peaking generations of electricity with much reduced impact on the environment. It is also much more versatile *than the hydrogen or oxygen fuel cell, in that it can use any light liquid hydrocarbon `like methanol, any products of coal gasification, as well as natural gas. If hydrogen becomes available, this same fuel cell will use it with even higher efficiency, merely by bypassing the reformer section. This device is now ready for demonstration. We hope it won't be over- looked in the rush to support the long-range, exotic energy sources that won't be ready to take their place in the system until after 1990. Hydrogen may, of course, be in great demand in other sectors of the energy and chemical industry as those preceding me have detailed. Given a large demand at a premium price by such users, electrolytic generation of hydrogen in selected cases may well find a substantial market. This is especially true where advantage may be taken of rela- tively inexpensive sources of elec;tricity, such as hydroelectric and, in special cases, off-peak nuclear generation. This would, of course, represent an electrical load for our industry which might eventually grow into a meaningful business activity. INTERMEDIATE RANGE (1985-2000) In the intermediate range, production capacity will expand to meet growing chemical markets, and limited quantities of hydrogen may become available to utilities with particular environmental constraints as a premium peaking fuel. Then, if cheaper techniques are identified, hydrogen production as a fuel for intermediate loaded devices, such as fuel cells, may be viable. It is not likely that electrolysis will be the source of a significant amount of electric utility fuel since it would probably be more economical to use the original electricity rather than suffer the multiple inefficiencies of conversion to hydrogen and then back to electricity. Of course, as the utility industry gets further involved in hydrogen production, it will assume additional markets in connection with chem- ical uses. A very sigrnficant such application would be in connection with coal gasification plants where use of an external source of hydro- gen, such as from a nuclear plant using water as the hydrogen source, can result in significant savings of coal for the same yield of synthetic pipeline gas. Thus, utilities have the opportunity for participation in a new business area, the production of hydrogen for external sales in addition to internal fuel uses, before the end of this century. LONG RANGE (BEYOND 2000) In the longer range there are few ultimate energy sources: Fission. fusion, solar, and (depending on resource extent) geothermal. More- PAGENO="0214" 208 over, there appear to be only two long-term energy carriers: Electricity and hydrogen. We are already beginning to realize that our irreplace- able hydocarbon assets have value as chemical resources that far ex- ceed their worth as simple fuels. Hydrogen and electricity in the long term can serve complementary roles in fulfilling energy markets. As energy carriers, each has specific applications for which it is the best and most cost-effective choice. Be- tween them. most if not all future end users of energy can be satisfied. The challenge is for the electric utilities to recognize their future as energy utilities, potential suppliers of both electricity and hydrogen. We would like to submit for the record a paper in which the long- range possibilities of hydrogen for the electric utilities are discussed at greater length. It appears as appendix C. This would be included in the material already entered into the record. Mr. MCCORMACK. Without objection, the document may be included in the record. [The document above-referred to is as follows:] PAGENO="0215" Michael Lotleer Northeast Utilities Hartford, Cons. ABSTRACT Presented is an overview of the "Hydrogen Economy", a concept in which sources of primary energy such as coat, uranium, deulerium, and suntight, are used to muke hydrogen, which serves as a synthetic fuel in many sectors of the energy consuming market. Specific techniques for the production, transmission, storage, and utilization of hydrogen are described. The impact on the entire energy economy in general and the utility industry specifically is discussed. Although experts may disagree over actual time scales, it is ctearthat our fossil fuel supplies are finite and will at some point cease to be economic energy resources. The competition for the earth's hydrocarbons by the chemical industry may further reduce their availability. Eventually, we will turn to nuclear (fission or fusion) fuels, to geothermal sources and to sunlight for our primary energy supply. From such primary energy sources we will need to derive a storable versatile fuel which can be used by IhO energy consumer and, as we shalt see, hydrogen is an excellent candidate for this ultimate synthetic fuel. Ills interesting and significant to note that this concept is analogous to, and perhaps a logical extension of, the present electric utility systerfi. Today utilities transform primary energy resources into electricity, which is more convenient, and in some cases, the only way the consumer can utilize the energy of coal, oil, natural gas, uranium, and flowing waler for his varied needs. It is, therefore, reasonable to expect that if anpther. convenient and useful form ofenergy, available from primary sources, is recognized, that the uljlity industry, expand its traditional roles to include the production, transmission, distribution, and sale of this "processed" energy alongside these identical activities with respect to electricity. Indeed, it is 1i~ird to imagine any indussry so well matched to the financial and operational requirements associated with the production of hydrogen from the large scale nuclear, solar or other facilities that~ are certain to be required: Thus, this concept may represent to the utilities, a new and expanded~ role as an energy industry, rather than just a supplier of electricity and natural gas. Is js.easy to believe that in the distant future, the hydrogen economy makes excellent sense and is, perhaps, inevitable. The more difficult task is to determine at what point in time, and in which uses, will hydrogen as a synthgtic fuel become a realistic alternative to our more conventional techniques of energy distribution. The answers to these questions are closely tied to the environmental, political, and economic values that our society sets C 74 099-8 for itself. In this connesitiosi there are some attractive near term possibilities such as (l)'~n urban areas where environmental rather than economic criteria might be limiting, and (2) load leveling, i.e., energy storage as hydrogen which could be delivered as electricity or as a gaseous fuel. FUFL Because of its abundance as an element and its essentially nonpollusing combustion characteristics, hydrogen is an excellent candidate for the ideal fuel. In normal combustion, the only product will be water; in certain high tensperature applications with rich fuel-air mixtures, there will be production of NOx, but these emissions may be less than with the equivalent application using. a fossil fsel. For example, in studies where hydrogen has been used as a fuel for an internal combustion engine, Murray and Schoeppel have shown that NOx emissions are considerably lower than .those produced by a gasoline engine.2 Hydrogen as a Safe Fuel Comparison of the chemical properties of hydrogen with those of methane suggests that hydrogen would be no less safe a fuel. While the minimum ignition energy at stoichiometric (chemically correct fuel-air ratio) mixtures is less for hydrogen than far methane, hydrogen's high stoichiometric ratio of 30 percent in air (compared with 10 percent for methane) coupled with hydrogen's much higher diffusion coefficient (about 3.1/2 limes that for methane) suggests that the explosion hazard in any gas leak may not be greatly different for the Iwo gases. The overpressures at explosions of stoichiomelric mixtures are about the same for methane and hydrogen; for a 10 percent mixture of hydrogen in air (the sioichionsetrie ratio for meihone), the overprnssurn for a hydrogen explosion is less than one-half that~for methane. Like methane, hydrogen is odorless and would have to be scented for pipeline LOCAl. POWER STATIONS INOI*TRIAI. FUEL AND REDUCING GAS EYNHaIEMIcALI AND LIQUID FUELS 209 THE HYDROGEN ECONOMY - A UTILITY PERSPECTIVE Elihu Fein Frank J. Salzano The Futures Group Brookhaven National Laboratory Glastonbury, Conn. . Upton, N. Y. New concepts are sometimes rejected a bit too quickly because they cannot mccl the economic competition of existing practice. However, if there is one lesson to be learned from the recent experience of the utilities, it is that yesterday's standard operating procedure may become today's controversial issue and tomorrow's INTRODUCTION prohibited practice. Economic comparisons of the hydrogen ecolsomy with our existing fossil fueled economy must be considered Recently, the concept of using hydrogen as a universal fuel tentative because of the uncertain effects of environmental and which would serve stationary or transportation applications and be . political considerations on the industry. manufactured from virtually any energy source, has caught the, imagination of several aulhors.' In this "Hydrogen Economy," the . HYDROGEN'S vii i vvas.i isv's via .`i'sinssrsavii.. - gas serves as a synthetic fuel in those energy sectors unable 10 utilize available primary sources, or where environmental impacts are of concern. The syslem is shown schematically in Figurt I. UNDERGROUND HYDROGEN TRANUMOWON LIQUID. HYDROGEN ELECTROLYZER STORAGE LARGE NUCL.EAR POWER COtI}tRfl~E PAPER . . .` $TATION . . C 711 099-8.. A paper recairnended by the ISlE Pager . . . ~ Generation Camu.ttee of the IECE Fcuver Engineering So- ~~RAGE DOMESTIC FUEL ciety for presentation at the ISlE PEE Winter Meeting Hew York1 H.Y. ,Januazy 27-Febrsaazy 1, 19711. Manta- . . ; . ~ ~ script subnitted September iT 1973 made available ________ for printing Novenber 26 1973 Price Members $1 50 All Rightn TRANSPORTATION No~g~nbers $2.00 Reserved . At Meeting: $1.00 by ~ Figure 1. .4. hydrogen Bused Energy Economy PAGENO="0216" 210 transportation; since it burns in air without a visibte flame, it atso might be necessary to add a chemical to make combustion visibte. It is known that hydrogen can cause embritttement in steet resulting in reduced ductitity and tensite strength. Recent work indicates that the effect seems to worsen with increased pressure and purity of hydrogen.3 The severity of the probtem with respect to pipetines remains uncertain, but note must be taken of the large numbers of hydrogen containers and lengths of processing pipelines that have operated for many years without failure.4 Ultimately employment of castings or inhibitors may allow the use of otherwise susceptible materials. Markets for Hydrogen Hydrogen may be used as a fuel for inputs to nearly all energy sectors. Where accelerating demands have foreshadowed diminishing supplies of elementary (fossil) fuels, and have raised to question the ability of the ecosphere to maintain its life-supporting equilibrium, hydrogen, produced from a minimum environmental impact primary source, can become the effective vehicle for energy transmission. A look at specific energy demands in the residential, industrial and transportation markets, shows that most uses are adaptable to hydrogen. It may be used as a direct substitute for natural gas for residential consumption, though burner adjustments changing the air-fuel ratio will have to be made in order to compensate for hydrogen's lower heating value. It is the natural fuel for hydrogen fuel cells for the production of electricity; replacing fossil fuels with hydrogen for direct use in the fuel cell eliminates the reformer (essentially a device to produce hydrogen from fossil fuel), thereby increasing the cell efficiency (to about 55% for hydrogen-air, and nearly 60% for hydrogen-oxygen) and reducing fuel cell plant capital costs. Proposed high efficiency combined-cycle gas turbines for generating electricity could be readily designed for~ using hydrogen as a nonpotluting fuel. In a longer range concept, direct combustion of hydrogen with oxygen in a high pressure combustion chamber, accompanied by quenching with water to moderate and control temperatures and pressures then followed by steam turbines, could yield efficiencies as high as 60-65% (all these efficiencies are based on the lower heating value of hydrogen). As has been mentioned, hydrogen may be substituted for gasoline in the internal combustion engine with relatively little engine modification. High pressure storage or cryogenic storage of hydrogen may be a problem in the vehicular design. It has been suggested that a regenerative hydrogen storage system be developed using the hydrides of tight metals such as magnesium or lithium.5 In such a system, hydrides are readily formed for the storage of hydrogen; the gas can then be released for use by the application of moderate heat to the hydrogen rich hydrides. Such systems will store hydrogen at approximately the same density as liquid hydrogen, but the total weight of the system is several times that of gasoline. The performance advantages obtained by replacing conventional jet aircraft fuel with liquid hydrogen derive from liquid hydrogen's high specific heat of combustion (61,000 Btu/lb., compared with 18,500 Btu/lb. for kerosene). Future hypersonic (speeds in excess of Mach 4) aircraft probably will be designed to use hydrogen, taking advantage of both its high energy density and its minimum polluting quality (only NOx and water vapor will be produced by its scransjet engine). Hypersanic plane designs may also make use of hydrogen as a structural coolant, so that despite its low mass density, it can be deployed and stored effectively throughout the aircraft. Direct reductio~ of iron ore is expected to become an increasingly important process in the next decade. The reducing agent in this process may be either hydrogen or a mixture of hydrogen and carbon monoxide, at temperatures ranging from 9000 to 1800°F. The hydrogen and the carbon monoxide react with the iron oxide to form metallic iron, water, and carbon dioxide. This reduced iron, in the form of pellets or briquets, may be fed to the steelmaking furnaces, open hearth furnace, or electric furnace, and it may also be used as part of the feed to a blast furnace. The economic advantages inherent in the flexibility of the direcl reduction system can be expected to provide a substantial demand for hydrogen in the future. With an abundant supply of hydrogen, we also can expect strong inputs to the chemical industry in the manufacture of methanol and ammonia, and in the production of alcohols and ethylene glycol. In fact hydrogen, generally from fossil fuels, but electrolytic in selected cases, is presently used to produce ammonia for fertilizers. Abundant supplies of hydrogen could also open up markets for the production of high protein food by biosynthesis of hydrogen and carbon dioxide, as welt as the production of methane by the anaerobic fermentation of hydrogen and carbon dioxide for such markets where methane may specifically be desired. Table I gives estimates for the potential usage of hydrogen by the year 2000. While these are not meant to be forecasts, they give indication of the diversity that markets for hydrogen can achieve and the magnitude of the demand which may be cultivated. Table 1. Major Future Demands for Hydrogen in the United States(a) Potential Usage by the Year 2000 (in billion ft3/yagy)_ As a fuel for 10% of air transportation 5900 As a fuel for all commercial vehicles (internal combustion) 32000 Supplying one-half projected deficit in natural gas 26000 In the direct reduction of iron 2000 In the production of methanol for use as a chemical 670 In the production of ammonia for use as a chemical 7000 For use in fuel cells to meet the additional need for electric peaking power req_aired foe the period 1980.1990(b) 2100 For use in fuel cells(c) meeting 10% of electric demand 16000 (a) Excluding the demand of the oil refining industry, which currently supplies its needed hydrogen as a by-product of the petroleum refining process. (b) Based on an added peaking capacity of 44,000 MW pumped hydroelectric storage and 20,000 MW gas-turbine and diesel for 1980-1990 (1970 National Power Survey). Fuel cell thermal efficiency assumed to be 50%. (c) Fuel cell efficiency assumed to be 60%. Source: E. Fm, "A Hydrogen Based Energy Economy," The Futures Group, Glastonbury, Conn. (October 1972). Transportatiun and Storage of Hydrogen High pressure gas lines may be used to transmit hydrogen to its principal markets. The cost of transporting hydrogen compared with methane in pipelines optimized for each fue~ has been estimated to be about 50 percent higher for hydrogen. At a pressure of 750 psi and for a flow rate of 120 million Blu pee year (sufficient to supply 2000 MWe by fuel cells 50 percent efficient), the cost of transmitting hydrogen is computed to be about 4.5 centsfMBtu per hundred miles; increasing the pressure to 2000 psi for the same throughput lowers the transmitting cost to under 4 cents/MBtu per hundred miles.7 Because hydrogen has approximately one-third the heating value of methane, considerably larger compressors with increased power consumption will be required to transport the same energy flow. Pipelines for hydrogen may be expeed to operate at greater pressures than those now operating for methane, resulting in heavier pipes wills increased capital costs. Nevertheless, the cost for transmitting and distributing hydrogen by pipeline may be PAGENO="0217" 211 expected to be tess than the cost of transmitting and distributing an equivalent amount of energy as electricity; where etectricat transmission is underground, hydrogen transmission becomes cheaper by a factor of 10 or more. Au a storable fuel, hydrogen presents an opportunity to operate power plants and electrolysis facilities on the more economical, base-loaded, basis. For short-range (hourly or daily) swings in demand, high pressure storage of hydrogen is feasibte. Pipelines, designed to operate at pressures higher than optimum for a given throughput, may be "packed" with gas to meet the daily peak demand. Cryogenic liquefaction of hydrogen is, in practice, a relatively inefficient process since the esergy required for liquefaction of hydrogen is a substantial fraction of the heating value of hydrogen. The operating costs for cryogenic storage wilt be very high, and one can anticipate that this type of storage will be used only for long-term cyclic changes or for emergescies. As mentioned above, storage in the form of metal hydrides may be. a feasible alternative to cryogenic storage, the density of hydrogen in each case being about the same. A large hydride storage system may be used to stock hydrogen at a fuel cell installation for meeting peak electric demands. Ultimately, hydrogen could be stored in the porous rock of emptied natural gas fields. Appropriate rock strata capable of containing the small hydrogen molecule mast be available, but storage costs in iuch cases will be one to two orders of magnitude less than the high pressure or ciyogenic storage methods. Hydrogen Production Processes for the large scale production of hydrogen are varied. Fossil facts (hydrocarbons) may be reformed by steam to produce carbon monoxide and hydrogen, or oxidized to produce the same products. The synthesis gas (CO-H2) is then converted in both the reforming and partial oxidation processes to carbon dioxide and hydrogen by the water gas shift reaction. Several hypothetical fossil fuel plants for producing hydrogen were analyzed by Mrochek, who found that hydrogen production costs, exclusive of raw material inputs, ranged from 35 cents/MBtu for steam methane reforming to 71 cents/MBtu for coal gasification.8 The raw materials costs are, of course, the key to the production costs of hydrogen. For example, at an oil price of $4 per barrel (somewhat less than current costs for low salfur #6 oil), partial oxidation process of fuel oil will yield a total production cost for hydrogen of Sl.27/MBlu (about the current price for jet fuel). Present electrolysis plants have a thermal efficiency of about 60 percent (based on lower heating value) for hydrogen productios. Advanced electrolysis cells promise to increase efficiency to nearly 80 percent and reduce the capital costs of the plant by about 50 percent. Commercial programs now being developed suggest that such advanced electrolysis systems may be commercially available within the decade. An analysis is based upon manufacturers specifications shows that the production costs, exclusive of electricity charges for these electrolysis systems, will be between 55 and 60 cents/MBtu of hydrogen.' Hydrogen production costs increase linearly with the cost for electricityand at a nominal cost of 10 mills/kWls the total production costs for hydrogen will be about $4.20/MBtu. A future but as yet unproven technique for hydrogen production is the disassociation of water through the application of heat in a multi-step chemical process. Of particular interest, and representative of a class of such processes, is the Mark I process proposed by DeBeni and Marchelti,9 which is designed to be ran by the process heal from the High Temperature Gas Reactor. The four steps of the process are shown in Figure 2. The theoretical cpper limit to the thermal efficiency of such processes is high (for Mark I it approaches 85 percent). Achieving good efficiency in an actual plant, however, will be difficult. The plant detign presents problems of manipulating very large amounts of materials without excessive pumping energy losses and transferring large amounts of heat across the relatively small temperature difference between the reactor coolanl and reaction temperatures. But with expectation of future success as a cheap source of hydrogen, the study of such multi-step processes is proceeding, and there is hope that eventually they may become economically viable. I) Water Splitting CaBr2 + 2H2O 7.30°C Ca(OH)2 + 2HBr 2) Hydrogen Switch Hg + 2HBr __2~Q~LHgBr2 + H2 3) Oxygen Shift HgBr2 + Ca(OH)2 ~_~200°cCaBr2 + HgO + H20 4) Oxygen Switch HgO _...600°C., Hg + 1/2 02 Whose sum is: H20 -~ H2 + 1/2 02 Figure 2~ The Mark-i Process SYSTEMS ANALYSIS The purpose of this analysis is to examine same concepts involving introduction of hydrogen in the United States energy system. Costs of energy delivered in various systems are examined and in some special cases the resource, environmental, and overall economic impacts are calculated. The following aspects of hydrogen energy system concepts are considered: (1) The economics of hydrogen energy delivery systems in comparison to electric delivery systems. (2) The application of the technology of hydrogen production, storage and reconversion to electricity for peaking applications. (3) The resource, environmental and economic impact of hydrogen generated with off-peak electricity as a clean fuel in the transportation sector, i.e., private automobiles and aircraft, and (4) A comparison of the impact of hydrogen and methane generated from coal for cue in transportation. Implementation of the above concepts is possible to a limited extent in 1985 provided research and development begin now and are vigorously pursued; however, in this analysis attention is directed toward the year 2000. The quantity of hydrogen that can be produced with off-peak electricity is limited by the central station electric forecast for the year 2000. In the case of hydrogen or methane produced from coal the required level of production is set at the same limit determined for the off- peak electric case in order to facilitate a comparison of theue options. In the case of electric energy storage the economics of hydrogen production and storage for electric peaking applications are compared with the only technique currently available, pumped hydroelectric storage. The basic technique employed in the analysis of the above concepts is described in a report entitled "Reference Energy Systems and Resource Data for Use in the Assessment of Energy Technologies" (AET-8).t0 Reference Energy Systems are presented in AET-8 for future years based ott the projected resource needs and environmental effects given no introduction of new technologies other than the LMFBR. New energy technologies may then be evaluated in terms of their potential impact on the reference system. the effects upon the patterns of resource consumption are shown in terms of Perturbed Energy Systems, derivgd directly from the Reference Energy System used in AET-8. These systems are flow-chart models in which projected energy demands, beginning with resource extraction and ending with sector utilization, are specified and allocated. Environmental effects are rndasured in terms PAGENO="0218" 212 of fossil fuel and radioactive emissions, and emission values are determinedfor both the reference year 2000 case and perturbed cases. These results are based upon emission factors given in AET-8 and Reference 11. Table V. discussed below, is an example of the results of such an analysis for imptensentation of hydrogen in the transportation sector. Unit Energy Cost Comparisons This analysis recognizes that etectricity is a clean and convenient energy form for the user and witt always futfitt a unique and necessary rote in the energy system. The reference energy system for the year 2000 shows that there are energy coeds which can be best satisfied with general purpose fuels. Thus, this analysis considers some energy transmission schemes that can supply either hydrogen or electricity. Hydrogen and electricity are highly compatible energy forms which are interconvertibte. Furthermore, a great many end~use applications can use either electricity or hydrogen. A point to consider is that the overall cost of energy to the user depends on the ratio of the electrical to generat.purpose fuel energy delivered to all end uses tn the energy system and today is approximately 1:10. For the ReferenceYear 2000 this ratio is approximately 1:4. It isalso inapoetant to eeeognize that in the nearterm coal is a primary source of energy from which facts such as hydeogen, methanol, methane, and gasoline can be derived inexpensively compared with the cost of production using only nuclear energy. The availability of coal is a crucial factor to consider in the application of hydrogen in the energy system. In this analysis the unit cost of energy delivered to the residential consumer has been estimated for a variety of energy delivery systems. The distinction between the cost of energy to residential customers and to commercial or industrial users is assumed to be only the cost of local distribution of the energy form, i.e., electricity or gaseous hydrogen, which for residential consumers, are assumed to cost S2.55/MBtu and S0.66fMBtu, respectively. The hydrogen energy delivery system can be broken down into a number of separate component operations such as fuel, praduction of electricity, production of hydrogen, storage, transmission, conversion of hydrogen to electricity, and local distribution. All the various process steps, including transmission and distribution, have inefficiencies associated with them which are considered in deriving the overall cpst of the energy delivered and have been assumed to be as follows: I) fuel conversion to electricity 32%, 2) hydrogen production 80%, 3) transmission of etectricity and gas 95%, 4) distribution of electricity and gas 95%, and 5) fuel cell conversion 65%. Table 11 shows a breakdown of the various costs for five of the systems considered. Case (a) is a nuclear electric system that uses a Light Water Reactor (LWR) to generate electricity in a cestrat station operatingwith a plant factor of 0.5. Case (b) is an example of a system that uses an LWR to produce hydrogen gas by an advanced electrolysis process. Case (c) is a system where the LWR generates hydrogen which is transmitted to a substation for conversion to electricity its a fuel cell and distributed in the conventional manner. Case (d) produces and delivers hydrogen using off-peak nuclear power. In this case only the fuel and operating costs of the plant and none of the capital costs are charged to the price of the electricity. It is recognized that the exclusion of capital charges may not be realistic in actual utility practice; this case is meant to establish a tower limit on the cost of electrolytically generated hydrogen. Case (e) is a breakdown of the cost of coat gasification in which the coal cost is assumed to be S0.29/MBIu. Energy transmission schemes producing gaseous hydrogen to be transmitted by pipeline to a substation where all the hydrogen is reconverted to electricity have merit only under very special conditions (see Case c, Table II). In circumstances where an aboveground right-of-way is not available or is very expensive, underground transmission of hydrogen and reconversion to electricity may be an attractive alternative. For example it is estimated that underground electric transmission may be between Table II. Cost Breakdown for Some Energy Delivery Systems a) This is a conventional nuclear electric system with a plant factor equal to 0.5. b) This system generates hydrogen gas with an advanced technology achievable with R&D. The plant factor for the electric plant is assumed to be 0.85 due to the better load characteristics of the hydrogen system. c) This system generates hydrogen and transports the gas to a fuel cell where it is converted to electricity. d) This system uses an advanced hydrogen production technology. e) The price of cool is assumed to be S0.29/MBtu. f) This assumes that the plant factor is 0.3 compared to 0.95 in the other cases. The total cost of S2.46/MBtu is reduced to SI.94fMBtu when the electrolytic plant level factor is increased to 0.95. g) Equivalent cost in mills/kWh. Fuel Production Hydrogen Production Transmission 300 Mites Fuel Cell Conversion Distribution TOTAL DELIVERED COST Nuclear Electric ) Nuclear Hydrogen (b) Nuclear Hydrogen Conversion to Electricity in Fuel Cell (c) Off Peak Nuclear Hydrogen (d) Coal Derived Hydrogen (e) 0.52 0.65 1.00 0.65 0.61 3.69 2.80 4.30 0.21 0.61 - 031 0.48 O.8~t~ 0.13 0.10 0.10 0.10 2.55 Electricity 689 (23.5~ 0.66 Gas 4.52 1.25 2.55 Electricity 9.68 (330)g 0.10 0.66 0.66 Gas Gas 2.46 1.98 PAGENO="0219" 5 and 20 times more expensive than conventional above-ground electric transmission systems, which could make underground hydrogen transmission and conversion to electricity an economic alternative. However, there are extra costs and inefficiencies in converting electricity to hydrogen and back to electricity. Under most circumstances it will probably not be realistic to consider such a system; however, when a significant fraction of the hydrogen transmitted can be used to supply nonelectricat needs, i.e., it can be used as a general-purpose fuel for stationary or transportation applications, then the economics of hydrogen energy delivery schemes may be attractive, The overalt cost of energy delivered in a dual system supplying hydrogen and electricity compared with that of conventional systems is illustrated in Table Ill. In this case it is assumed that 25%.of the hydrogen produced is liquefied. The ratio of fuel to electric requirements is assumed to be 4:1 and fael,cells are used to supply the electrical needs, It is evident that a dual system delivering both electricity and hydrogen is competitive with an all-electric system, In an advanced technology the overall energy cost, i.e., gas and eleclricity, is estimated to be $6.l0/MBtu, and $7.59/MBtu if presently available technology is used to implement such a system. These prices are almost competitive with the delivered price of nuclear electricity. Table III. Cost Comparison, Dual System vs. All Electric S/MBtu Advanced Present Technology Technology I) Nuclear hydrogen with liquid storage delivering gas and electricity in the ratio of 4:1 where 25% of the hydrogen produced is liquified and fuel cells supply the electrical re- quirements. 610a 2) Nuclear all electric with a toad factor of 0.5. - 6.89 3) Nuclear alt electric with a load factor of 0.85. - 544b a) If none of the hydrogen is liquified, the overall cost is reduced to $5.55/MBtu. b) Equivalent to a delivered cost of ".. l.9~/kWh. (The production cost for this case was "- 8 mills/kWh.) Electric Energy Storage The elements of hydrogen production, liquefaction, storage, and reconversion to electricity can form the basis of an electric storage or loud leveling system. Using advanced technology, such a system could be competitive with conventional pumped hydroelectric slorage. In this system electricity produced during off-peak periods in ais electrolytic hydrogen plant operating at a plant factor of 03 is liquefied and stored. During the peak demand period the hydrogen is converted to electricity in a turbine or fuel cell operating at a plant factor of 0.1. It is estimated that the electricity produced ix such a system using present day technology would cost approximately S23/MBtu for a system with turbine converters and approximalely $31/MBtu using fuel cells. A research and development program that would reduce the cost of hydrogen production and increase the efficiency of turbineu and fuel cells as well as reduce their cost, could reduce the price of electricity derived in this type of system to approximately 5l2/MBtu. Delivered energy costs for a hydrogen storage system both for present and advanced technologies, are compared to pumped hydroelectric in Table IV. Although the costs presented must be considered speculative, one can still conclude that research and development could make energy storage with hydrogen competitive with pumped hydroelectric storage costing in excess of 82001kw of installed capacity, a reasonable estimate for future pumped storage capital costs. The technology required to implement this type of energy storage is available at the present time but the cost of electricity would be a factor of two higher than that achievable with pumped storage. The cost of load leveling using hydrogen is high primarily because of the inefficiencies of reconversion to electricity, the high cost of the conversion devices, and the relatively poor load factor of both the hydrogen production plant and conversion devices. If markets ore available for nuclear-derived electrolytic hydrogen, it is more reasonable to build hydrogen production plants which can be used to supply electricity for short periods of time to meet peaking needs. The major fraction of the time these plants would be operated to produce hydrogen which could be supplied for transportation, residential, or industrial applications. Thus, the development of large-scale uses of electrolytic hydrogen and the necessary production facilities could have a significant impact in supplying peak electrical demands in the near term. Resource, Economic, and Environmental Impacts A summary of the significant resource, economic and environmental impacts associated with the implementation of hydrogen production from offpeak power for use in the private transportation sector and the similar application of coal derived hydrogen and moihano arc given in Table V. The first three implementation schemes, listed in Table V under the heading Perturbed Year 2000 - I, - II, and III, represent three nuclear implementation options which are as follows: 213 Table IV. Cost of Electric Peak Shaving Using Hydrogen Storage as Liquid (S/MBtu Delivered) ~pyrationu Present in Turbines Advanced in Present Fuel Cells Advanced Pumped Storage at ~~Q/kW Nuclear Fuel 2.19 1.46 1.75 1.35 0.70 Conversion to Electricity 0.70 0.47 0.56 0.43 0.22 Conversion to Hydrogen (.17 1.92 6.53 1.77 - Liquefaction 3.75 2.50 3.00 231 - Storage Tank 0.54 0.54 0.54 0.54 - Reconversion to Electricity 793 5.33 1830 533 10.39 TOTAL COST OF PRODUCTION PAGENO="0220" Table V. Summary of Resource, Economic, and Environmental Perturbations Including Reference Year Data for the Year 2000 Annual Coiss (1095/yr) Capitat Construction (Power ptant, elect. H2) Fuet (Power ptant) (Automobile) Operation and Maintenance (Power plant, elect. H2) Transmission (Gasoline, H2) °~ Local Distribution (Gasoline, H2) Total Reference Annual Resource Consumption Year 2000 Case 2000-1 (1015 Btu/yr) Coal 36.4 +11.1 Oil 65.5 -4.7 Natural Gas 27.9 +2.6 u235 25.5 +5.87 U238 ~fl 6 +475 Totul Case 2000.11 -7.5 +14.8 +12.0 +1 9.3 175.8 +19.6 Case 2000-Ill .264 .130 +0.6 +30.6 +24.5 +16.3 69.1 13.6 19.6 3.94 2.35 10.9 Case 2000-tV +10.0 -7.5 0 0 0 +2.5 +5.7 +2.8 .9.8 +0.6 -0.48 -0.55 -1.75 Automotive Utilization +1.11 +5.8 -9.8 +3.1 -9.8 -2.0 -9.8 +1.9 +1.9 +1.9 .0.48 .0.48 -0.48 -0.55 -0.55 -0.55 +3.07 +11.6 -3.53 Automotive Utilization Aircraft (or) Utilization Automotive Utilization Automotive Utilization Aircraft (or) Utilization 20.1 +2.11 +2.12 -1.12 -6.89 -6.88 Case 2000-V +11.4 -7.5 0 0 0 +3.9 +6.2 +3.3 -9.8 +0.7 -0.48 -0.95 -1.03 Automotive Utilization +1.42 Emissions and Wastes~1~ a) Fossil Fuel CO2 (1012 lb/ye) SO2, NOR, CO, Particulates, Hydrocarbons (t0~ lb/ye) b) Radioactive T, Kr (106 curies/yr) Stilid High Level Wastes (lO3ft3/yr) Population Exposure (lO3man-rems/yr) 192.4 +2.02 +9.7 -7.4 .56.8 -67.2 -7.4 -0.7 181.3 +41.7 +41.7 +105.6 +217.3 +217.3 0 0 54.0 +12.4 +12.4 +31.6 +64.5 +64.5 0 0 318.0 +73.4 +73.4 +186.1 +379.9 +379.9 0 0 No4e (1) Computed utilizing emissions tables given in Reference 10 (AET-8). PAGENO="0221" I 215 I - The production of hydrogen from off peak power in the electric utilities are projected to exist by the year 2000 Reference Energy System's mix of coal, gas and nuclear fuels. II ` This case is the same as case I except that the available off-peak electricity from fossil fuels is replaced by base loaded nuclear plants. III Generation of the same amount of hydrogen from off'peak power as in cases I and II; however, in this case the system is all nuclear and no coal, oil, or gas are consumed by the utility system. The above serve as sample analyses and are meant to demonstrate the perturbation technique as well as to examine selected canes. The assumptions were formulated to indicate trends by examining limiting cases; therefore, values so generated are significant only in a relative sense. Work continues to develop more detailed and realistic assumptions. These options have an impact upon the need for increased oil imports and the growing requirements for stringent controls on air quality. The petroleum resource consumption decreases in each case, and under the all'nuclear scheme (year 2000-Ill), the greatest saving in petroleum resources is realized. This savings could substantially reduce reliance on foreign sources of petroleum, perhaps allowing a 15 to 20% decrease in the projected imports. The cost results show that, with exclusion of development costs of a portable hydrogen storage system suitable for use in ground transportation vehicles, the reference off-peak hydrogen case (2000-I) is directly competitive with gasoline. If in the year 2000 electricity is all nuclear generated (2000-Ill), a substantial overall savings can be realized. This is due to the reduced cost associated with operating base loaded nuclear'electric power plants relative to a cycling fossil fuel plant, and the savings in crude oil and refining costs. Emissions in the transportation sector are shifted in each case from high'level concentrations in populated urban centers to central station electric sites, making them amenable to improved methods of power plant emissions control and providing a mechanism of dispersion that allows an acceptable overall level of air quality to be maintained. Although the year 2000-I case shows an overall increase in fossil.fuel emmisnions they are shifted away from being dispersed in urban centers to highs level emissions at the central station. Following the off-peak electric implementation nchemes,.Table V lists the results for the gasification of coal into hydrogen (perturbed yegr 2000-IV), and, for comparison, methane is considered as an alternate fuel from coal (2000-V). The resource perturbations show an increase in coal consumption that is only partially offset by the decrease is oil consumption since the consumption of oil is exchanged for a larger (about 35%, due to conversion efficiencies in the gasification process) coal consumption. The cost numbers indicate that gasification is directly competiti" with (I) gasoline as in the reference case, (2) the perturbed year 2000-I, and further, that no economic basis exists for a ,isoice between hydrogen and methane from coal. The primary environmental advantages of hydrogen from coal over the previous cases are the lack of radioactive emissions and the absence of the problems of radioactive waste disposal and storage. ~ygh~s Analysis Su~~y Although it contains many simplifying assumptions, the preceeding systems analysis indicates that the widespread use of hydrogen as a synthetic fuel may be justified on both economic and environmental grounds. More recent work with a linear optimization model of the total United Staten energy system suggests that as early as the year 1985 it might be economic to produce hydrogen from off'peak electricity and this could be sued to supply approximately 1-3% of the total thermal demand depending on the availability of oil. - Serious consideration should be given to eventually changing the operating philosophy of utility systems which is presently to have a base load capacity supplemented with large amounts of intermediate and peak-loaded plants designed to serve the fluctuating electrical load. It may be more advantageous in the longer term to design the electric generating system so there is sufficient base load capacity to meet the peak demands and use the capacity available during the off'peak periods to produce hydrogen to satisfy thermal, transportation or emergency electrical demands. The system analyses examples discussed above are limited in scope and serve as a preliminary or sample analysis. A more complete analysis is required which will make a more realistic and detailed assumptions about possible system characteristics as well as end use efficiencies and appliance or vehicle costs. Furthermore it is evident that realistic total costs for resource use and for emission controls and effects need to be applied to make final judgements about the relative merits of the various cases studied. Nevertheless, it seems clear that the use of coal and nuclear off-peak power, although limited in extent, can provide a low'cost substitute for natural gas, and that a nuclear-hydrogen system may be competitive with a nuclear-all electric energy delivery system. HYDROGEN AND THE UTILITY INDUSTRY ~p9ēt on the Utility Industry There are few problems facing the utility industry today as serious and immediate as the procurement of the necessary approvals for siting generation and transmission facilities. Opposition to these installations exists due to several reasons, from environmental problems, which may be subject to engineering solutions to aesthetic considerations that, in connection with power planta and related items, are often not readily resolved. If this trend, which forces the remote siting of power plants, is combined with the public's dislike of overhead transmission, the result may require extended underground (or undersea) transmission of large amounts of electrical energy. These are conditions conducive to the use of hydrogen by the utility industry. If solar energy is to play a role in central station energy generation, the location of such installations will be determined by considerations other than load proximity. In fact, the requirement for low land costs and high.isolation areas make the need for long distance transmission of energy inescapable. Even in the more exotic manifestations of solar energy that may be profitably tapped such as wind and sea thermal gradient power, the transmission requirements are not likely to diminish. For the potential of solar energy to be widely exploited, the utility that owns and operates the plant may direct only a fraction of its output as electrical energy. The remainder can be used to satisfy demands in other energy sectors, as a transportation fuel, an industrial chemical, and source of thermal energy. The attraction of a universal synthetic energy medium which can satisfy these markets is clear. In an economic comparison of the hydrogen economy with d'ternatives, care should be taken to consider total system costs. For example, in comparing energy transmission by electrolytic hydrogen in an underground pipeline for reconversion at a fuel cell versus an underground electrical cable, one would tabulate the costs for the electrolyzer, pipeline and fuel cells and assign them to the hyd .vr~ system. Then a comparison might be made between energy storage techniques; hydrogen and pumped hydroelectric. In this separate comparison, one would similarly tabulate the costs for electrolyzer, storage facilities, and fuel cells and again assign them to the hydrogen system. Note that in an overall systems view the same electrolyzer sod fuel cells used for energy transmission would be used for hydrogen storage. Thus the total cost of the hydrogen system will be less than the sum of its subsystem costs considered separately. The `4me may not be true of alternatives. The eventual attraction and overall economies of the hydrogen concept will be realized only if the components' costs are spread over all systems uses. Hydrogen offers other advantages to a utility that become apparent upon systems' `evaluation. Oves~a1l reliability should 7 PAGENO="0222" improve for several reasons. Most important is that the element of time is tess crucial. The time scale for correcting a problem before it can cascade into a serious disruption of service, in a hydrogen transmission system, wilt likely be measured in seconds, minutes, or even hours, rather than small fractions of a second as is true in the case of AC electrical transmission. Reserve requirements would be doubtlessly eased. At present a system's electrical reserve is a mixture of spinning reserve (units operating at less than 100% rating), 5 minute reserve, and sources available at longer intervals. Since fuel cells at operating temperature can change power levels from zero power (standby condition) to maximum output in a fraction of a second, a good deal of the required electrical reserve on a hydrogen system might ronsist of any of the previously mentioned hydrogen storage concepts combined with these fuel cells. Maintenance and repair of a hydrogen delivery system would present its own special problems, such as those in connection with leak detection and safety, but in general a gas pipeline wilt be less sensitive to the effects of weather, the environment, and malicious treatment, than its electrical counterpart. The natural storability of hydrogen, combined with the fact that the utility may be producing the gas to supply a wide spectrum of the energy market, could result in an increase in the overall load factor of the associated equipment. The power plants that produce hydrogen, and the pipelines that transport it, serving major industrial and commercial gaseous and electrical needs during working hours, can continue to function for the remainder of the day in connection with storage facilities at these and other sites. Residential users could, during off peak hours, charge their automobile tanks from an outlet in the home. It may even prove economic to store hydrogen on a seasonal basis if the appropriate storage technology (underground storage in geological formations) is feasible. With proper planning and economic incentives to the customer, this enhanced diversity of load and improved load factor will be translated into substantial system benefits. The true costs and advantages associated with the hydrogen economy wilt be specific to the particular load served, and fully attainable only when extensively implemented. Factors Influencing the Time Scale for Utility Usage of Hydrpgpe The two r~ajor forces serving to accelerate the introduction of hydrogen into general usage are the increased environmental and political constraints under which the energy industries must operate. These wilt then determine the relative economies of allowable alternatives in addition to providing direction for appropriate research. Conversely, a relaxation of these constraints would doubtlessly delay the economic viability of the hydrogen economy. In the past few years, the environmental movement has had a dramatic, and largely unpredicted effect on utility operations. Clean air legislation has restricted coal as an available fuel on the casters seaboard, resulting in the use of expensive low sulfur oil as a necessary substitute. Thermal discharges, often classified as pollution, have been regulated with the result that utility planners can no longer rely on the most economical once'through technique for cooling, but must instead consider cooling ponds, and towers in their power plant planning. Such projects as pumped hydroelectric storage installations, transmission lines, and distribution systems have been literally forced underground, delayed, or abandoned due to aesthetic and land'use considerations. The matter of nuclear safety, with its question of the high price of protecting a system against accidents of vanishingly small probabilities again raises the problem of balancing the cost-benefit equation. The future will demonstrate the wisdom of these movements and their attendant decisions; the point is, environmental considerations are forcing, and will continue to force changes in the way we supply energy, and in that light hydrogen is an attractive future alternative. It is not clear whether this trend wilt continue or suffer an anti-environmentalist "backlash". However, the environmental costs of the strip mining of coal, the trans-Alaskan and trass'Canadian oil pipelines, off'shore oil production, creation of deep water ports to facilitate importation of oil, and the construction of refineries 216 to process the oil into useful forms are presently being debated. Clearly, any decision to delay or prohibit these endeavors will increase the cost and reduce the availability of fossil fuels,ihereby improving the retativ'e economic stature of hydrogen as a synthetic fuel. Related in spirit, if not in scope to the above, is the public's desire to keep their local community free of anaesthetic power stations, transmission tines, substations, natural gas (or LNG) storage tanks etc. The appeal of a remotely generated, invisibly delivered, pollution free fuel will probably generate mach attention and support. The hydrogen economy is not, of coarse, the answer to alt environmental problems because a source of primary energy is necessary. Since today's most promising candidate for this source, nuclear power, is itself the subject of considerable controversy, we should recognize that delay in the proliferation of nuclear power will probably delay the introduction of the hydrogen economy. An additional point of environosentat concern wilt likely be the inefficiencies associated with the multiple conversions of energy. Here, society will have to consider the thermal effects of these inefficiencies, and the nature of this wasted energy; is it a valuable national resource, could it be used more wisely (uranium resources. for example, probably could not), or does it belong to the class of virtually infinite (solar and fusion) energy supplies? The realities of world politics will certainly be of major significance to the introduction of hydrogen on a large scale. The national security sacrifices and balances ol payments implications, attendant to the importation of vast quantities of fossil fuels that wilt be necessary, may be deemed to hold overriding importance. James E. Akins, director of The Office of Fuels and Energy of the U.S. Slate Department, has outlined the potential problems.l2 After 1980, he projects domestic consumption of oil rising to 24 million barrels/day, with U.S. production only about half this figure. Of the remaining demand, about 3 million bbl/d wilt come from the Western Hemisphere and a full 9 million bbl/d from the Eastern Hemisphere, principally the Middle East. The security risk is clear. Wilt Arab nations restrict exports for political reasons? The economic questions are equally obvious. What economic impact will a 20 billion dollar/year balance of payments deficit, from oil imports alone, have on our economy? Moreover, what effect on world monetary stability would a Middle Eastern income of more than $50 billion/year (by 1980) have? In an analysis of the likelihood of such an international situation developing, one should note that the recent trend for oil producing nations has been to restrict production in the expectation that oil in the ground will appreciate faster than alternative investments.t2 In addition, other industrial nations such as Japan and those of Western Europe, have a need to import oil that is perhaps even more urgent than our own. Arab nations would not pay much of an economic penalty is interrupting oil supplies to a given country. This unstable political situation may dictate the necessity for relying on domestic resources. Since these resources are oil and gas deficient, some form of synthetic fuel will be required to supply many energy markets. It is recognized that the United States has considerable coal reserres of its own and that research towards the gasification and liquification of coat is currently enjoying widespread support that wilt properly be - expanded in the future. In addition it is estimated13 that the oil shale deposits in Colorado, Utah, and Wyoming alone contain the equivalent of two trillion barrels of oil. Added to domestic production, these deposits could welt supply oar oil needs for many decades to come. The economic and environmental costs of utilizing these resources, largely unknown at this time, wilt be crucial in determining the time scale associated with the arrival of the hydrogen economy. An inexpensive fossil fuel could place almost insurmountable economic competition on electrolytically generated hydrogen. It may be, however, that end-use environmental restrictions, especially in urban areas, and overall systems' economies might stimulate the widespread production, distribution, and utilization of hydrogen from these fossil reserves. This would have the added benefit of providing the basis for a smooth transition to hydrogen generated from other, non'fossil sources when the appropriate time arrives. The appearance of the hydrogen economy might be PAGENO="0223" 217 substantially advanced by successes in the many non-fossil energy research areas. The best exampte of these is, of course, the breeder reactor which promises to suppty energy for centuries. The energy resources for fusion reactors are even greater than this by orders of magnitude. In fact, if onty 1% of the ocean's naturatty occurring deuterium were "burned" in a fusion reactor, and utilized at a 10% efficiency, it woutd provide energy enough for 7 bittion people for 3 mittion years at twice the U.S. per capita consumption.' This tremendous ultimate energy potential could only be used throughout all areas of the energy market in connection with a suitable synthetic fuel. As for other non-fossil energy sources, the geographical limitations and intermittent nature of solar, wind, and tidal power concepts make the use of hydrogen, as a transmission and storage medium, attractive. The impact of future technology on those areas associated with the hydrogen economy and the areas associated with competing alternatives is critical and impossible to predict. Each problem area that has shown itself to be amenable to solution with the use of hydrogen, may also be solvable in other ways. For example, an economic, high energy and power density secondary battery would provide many of the advantages of hydrogen in connection with vehicular use and utility load leveling. Currently this particular area is the subject of active research. Reseurch successes in those areas cruciul to the production, transmission distribution, and utilization, of hydrogen may improve the economics, broaden the applicability, and reduce the development time required. Such research is currently proceeding at a relatively low level although an important exception to this is the ambitious fuel cell program, supported by several utilities and a potential utility fuel cell manufacturer. These first fuel cell installations, which will have the capability to reform petroleum dintillaten info hydrogen, could some day be supplied directly from hydrogen pipelines. CONCLUSION We have attempted to provide an overview of the hydrogen economy; its components, its applicability to specific needs, its position in a systems' view of the U.S. energy system, and its relation to the utility industry. In addition, we have tried to project those circumstances likely to have a criticut impact on the timing of the appearance of the hydrogen economy. We conclude that due to the intrinsic limitations of hydrocarbon supplies, some form of synthetic fuel witl eventually enjoy widespread use. With appropriate en"ironmentat and political constraints, it is possible to project the introduction of such fuels on a time scale not much longer than that of present utility planning. Hydrogen is seen to have sufficiently attractive physical and chemical properties to be a leading contender for this fuel. The utility industry is uniquely suited to provide the transition to, and economic and technical management for the hydrogen based energy economy. It should regard this option as a possible part of the ultimate solution to our energy nreds along with the breeder, fusion, and solar power. As such it should command an appropriate share of utility research funds allocated to such long range priorities. REFERENCES (I) See for example the Conference Proceedingu of the 7th Intersociety Energy Conversion Engineering Conference, Sessions on Hydrogen Energy Systems, pp. 1312-1402, Sept. 1972. (2) R. G. Murray and R. J. Schoeppel, "Emission and Performance Characteristics of an Air'Breathing Hydrogen Fired Internal Combustion Engine," Paper No. 719009, Intersociety Energy Conversion Engineering Conference Proceedings, Society of Automotive Engineers (August 1971). (3) R. P. Jewelt et.ul., "Hydrogen Environment Embrittlement of Metals." Rocketdyne Division of North American Rockwell, NASA CR-2l63, 1973. (4) D. P. Gregory et.al., "A Hydrogen-Energy Distribution System." American Gas Association L2l173, 1972. (5) K. C. Hoffman, W. E. Winsche, R. H. Wiswatl, J. J. Reilly, T. V. Sheehan and C. H. Waide, "Metal Hydrides usa Source of Fuel for Vehicular Propulsion," Paper No. 690232, Intersational Automotive Engineering Conference, Society of Automotive Engineers (January 13-17, 1969). (6) G. Beghi, 3. Dejace, G. Grassi and C. Mussaro, "Transport of Natural Gas and Hydrogen in Pipelines," Euratom Internal Report 1550, Ispra (May 1972). (7) E. Fein and 3. G. Stover, "Hydrogen: A Fuel for the Electric Utility," The Futures Group, Glastonbury, Conn. (May 1973). (8) J. E. Mrochek, "The Economics of Hydrogen and Oxygen Production by Water Electrolysis and Competitive Processes," Abundant Nuclear Energy, U.S. Atomic Energy Commission (May 1969). (9) G. DeBeni and C. Marchetti, "A Chemical Process to Decompose Water Using Nuclear Heat," American Chemical Society Symposium on Non-Fossil Chemical Fuels, Boston, Mass. (April 10-14, 1972). (10) Reference Energy Systems and Resource Data for Use in the Assessment of Energy Technotogie% Report No. AET-8, Associuted Universities, Inc., April 1972. (II) W. E. Winsche, K. C. Hoffman and F. 3. Salzano, The Future Role of Hydrogen in the Nation's Energy Economy, ~j~nce Vol. 180. pp. 1325.1332, June 29, 1973. (12) J. E. Akins, "The Nature of the Energy Crises," Journal of Petroleum Technology, Vol. 24, pp. 1479-1483, Dec.1973.. (13) H. C. Hottel and J. B. Howard, New Energy Technology - Some Facts and Assessments. The MIT Press, 1971, p. 195. (14) M. Eleccion, "Prometheus Bound," IEEE Spectrum, Vol. 10, p. 64, Jan. 1973. 9 PAGENO="0224" 218 ELECTRIC TJTILITY INTEREST IN HYDROGEN-WHY? Today's electric utility is concerned with securing primary energy resources, converting them into a. conveniently transported and utilized synthetic. energy form (electricity), distributing the energy to the customer in a configuration optimized to his needs, and ultimately monitoring consumption and billing the. energy user. If another syn- thetic energy form (hydrogen), also derivable from primary energy sources, easily transported and consumed awl easily converted to and from electricity, were identified. it would be a logical extension of the utility industry's present. activities to include the pI'oth1ctioli, distri- bution, and sale of this second product alongside these identical roles with respect. to electricity. Hydrogen may well become the product transmitted from certain energy generation concepts such as solar, wind, or ocean thermal gradient. schemes, or applications of conven- tional forms of generation such as remote nuclear parks. The nuclear and solar power sources that are expected to provide primary energy for the hydrogen-electric economy are all character- izecl by small or absent. fuel costs and high capital costs. This economic fact of life will define the fiscal structure of any company that hopes to earn a return on investment by selling hydrogen. Today the electric utility industry is by far the most heavily capitalized industy. Gas, oil, and coal companies are basically distributors of bulk materials. Their product. is. in many cases, delivered in essentially the san~e form as when it. left the original source. Electric utilities, as noted above, sell synthetic energy. They have considerable operating experience in treating the. raw energy of flowing water, coal, oil, gas, and the atom and optimizing conversion and delivery pi~ocesses with the consumer, stockholder, and government regulator in mind. Given an appropriate regulatory climate, the growth of electric utilities into energy utilities, which would supply both hydrogen and electricity. may be an attractive possibility. A. possible combination might be to utilize the strength of the electric utilities in ownership of largescale energy conversion devices with the gas utilities' expertise in transmission and distributon of gaseous energy. WTith both hydro- gen and electricity in the delivery system. energy storage should come much more naturally than it does in an all-electric system. Moreover~ transformation from electricity to hydrogen and hack again using fuel cells and electrolytic devices can be easily accomplished where war- ranted in order to meet peak dlemafldlS for either energy form. LEGAL. ENVIRONMENTAL. AND ECONOMIC ISSUES The resolution of the man legal issues assoeiatedl with the massive change in energy systems from todlay's natural gas and petroleum dominated economy to tomorrow's combined hydrogen and electric economy will determine the ease with which this change can be made. While hydrogen is generally thought to be. environmentally benign, environmental issues associated with all pl~ases of hydrogen energy systems need careful and continuous evaluation. In the economic area, the key question will be whethei' hydrogen will compete via the ac- tions of the marketplace in increasing the p~c~ of alternatives, or by direct governmental incentives for conservation of fossil supplies. The PAGENO="0225" 219 danger is that the market price of fossil fuels will be low enough over the next few decades to preclude substitution by synthetic fuels. This would result in rapid resource depletion and a delayed, but more dif- ficult, transition to nondepletable energy sources. CONCLUSIONS Our fossil resources are, of course, finite; renewable sources of en- ergy must eventually be brought to bear to feed an economy and society that is becoming increasingly energy intensive. To meet all our needs, synthetic energy forms in addition to electricity will certainly be needed. Hydrogen and hydrogen-rich fuels, such as methanol or am- monia, have chemical and physical properties that make them excellent candidates for such application. The arguments raised in opposition to the development of hydrogen energy systems are those of efficiency and cost. Efficiency will, of course, become less of a factor with utiliza- tion of the virtually infinite nuclear and solar energy resources. The cost argument will fall with the rising costs of alternative energy sources and with the realization that our fossil resources are far too limited and too valuable to burn. At Northeast Utilities we have a substantial commitment to further investigate hydrogen energy systems for our long-iange future. It is our belief that hydrogen production facilities may become important consumers of electricity within a time scale not much longer than that of present utility planning and in the long run hydrogen, as an energy carrier, may well be as important to our industry as electricity. Thank you, Mr. Chairman. If there is time, my colleague, Mr. Lot- ker, has some comments regarding `the special significance of hydrogen to fusion and solar. Mr. MCCORMAOK. Go ahead, Doctor. Mr. LOTKER. Thank you, Mr. Chairman. I would like to note that our studies of the solar and fusion energy options point to some unique ways in which the use of hydrogen can help overcome otherwise potentially serious interface problems. The leading solar and fusion concepts have outputs that are, of necessity, not continuous. In the case of solar, this is apparent for wind power, solar, thermal, and photovoltaic schemes. With fusion, this is less obvious, but this is just `as true for the Toko- mak and other pulse fusion concepts. For these devices to supply a large fraction of the utility systems load, some form of energy storage is required. Hydrogen generation from such devices solves the storage problems while decoupling the stability of the energy delivery system from momentary fluctuations in the energy source. Hydrogen's ability to easily interface with advanced energy generation concepts is, I feel, worthy at this time of the committee's consideration. Thank you for your indulgence. Mr. MCCORMACK. Thank you, gentlemen. I am going to ask one question at this time of Mr. Lotker. Then I will turn to the other mem- bers for any questions they have. Mr. LOTKER. Yes, sir. Mr. MCCORMACK. There is something I do not quite understand. You refer to the intermittent characteristic of fusion and solar energy. We recognize that Tokomak is a pulsed system and most systems that 62-332 0 - 76 - 15 PAGENO="0226" 220 we are talking about are pulsed systems. Obviously, there will be a reservoir there. We will use the same cycle conversion system to gen- erate electricity in the foreseeable future. I do not see th~at as a pulsed system. I am curious at this time to know how you relate this. Could you comment on this? Mr. LOTKEIi. One of the things that has struck us is the UWMAK-1 fusion design. They have a 90-minute burn time that is followed by a 6.5-minute downtime in the fusion reaction itself. This is compensated in the scheme by a large reservoir of liquid sodium which causes us some concern. It is in this regard that the use of hydrogen has a de- coupling effect. In the laser fusion concept, if the laser design is such that it might miss a few shots now and again, this would cause a mo- mentary drop in the electricity output with a purely thermal energy interface. It would not have as serious an effect with hydrogen production. Hydrogen is an option that may possibly remove some of t.he problems. Mr. MCCORMAGK. Thank you. Mr. Thornton, do ou have questions? Mr. ThoRNToN. Thank you. If I may pursue that, Mr. Lotker, the internal combustion system is a. pulse system with storage that is ac- complished by a flywheel. Is that correct? Mr. LOTKEIi. Yes. Mr. TIIoRxTox. Depending on the length of the pulse and the ca- pacity of the storage system, that can be a problem or one that can be overcome. I think, more interesting, is the possibility of hydrogen as a storage for peak loading problems that are spread over a greater and more irregular period of time than we might expect from the fusion generator. Do you agree with that? Do you agree at this time with that evaluation as to the storage potential, that it would be greater as a means to overcome peakload variations? Mr. LAW. Are you referring to variations in electricity networks? Mr. ThoRNToN. Yes. Mr. LAW. That is one of the strengths of hydrogen. It can be stored. IVe have not been convinced as yet, however, that the use of hydrogen aiid the fuel cell is as economic for this pullose as is the high-energy storage battery that we are also developing through the Electric Power Research Institute. This is au open question. There is the definite pos- sibility to use hydrogen in that manner. Mr. TT-IoRxTox. I am interested in getting more information on this either from these witnesses or others, i\ir. Chairman. That is, as to the cost of capitalization for this kind of work. I think that. is bound to be a very significant factor to determine the. economic feasibility. I hope that we will have some information, even if it is just. estimated. I)r. GREGORY. In the storage. situation, it seems that the conversion 0± electricity to hydrogen and back again, that this is something that will cost money. It will cost efficiency. You can add capacity to the storage tank with hydrogen more cheaply than you can with the batteries. Hydrogen storage~ Mr. Chairman, looks more. attractive to me for very large storage capacity systems and for the actual relatively short- term systems; there, the battery looks better to me. You can't say that one looks better than the other. They have completely different char- acteristics. On capitalization, the cost of electrolyzers, well, this is PAGENO="0227" 221 something between 10 percent and 20 percent of the nuclear plant that drives them. As to the cost of transition equipment, much of this is probably already in place. The cost of conversion of gas-burning equipment to hydrogen is relatively small, I think, compared to the tremendous capital cost of building a primary energy source, such as windmills or nuclear plants. Mr. Tn0RNT0N. In that regard, is hydrogen more fugitive in nature than methane? Are there any problems about the very minute porosity that the pipelines have that might be actually exacerbated by hydrogen? Dr. GREGORY. Yes; hydrogen tends to leak through a hole at about three times the rate of natural gas. About the same number of Btu's per hour would leak through the same hole because of the difference in energy density. Mr. ThoRNToN. You have some systems with 8 percent or 10 percent unaccounted-for loss for gas. Dr. GREGORY. Yes; some is not just leakage. It is used in the trans- mission. If you have a leak with methane, you have a similar leak in, or with~ hydrogen. One misunderstanding at this time is that hydrogen, that the mole- cule is so small that it will get through a hole that methane will not get through. We have not found any porous systems that do that, or have that kind of separation. If we could, we could put it to good use. That is one of the hardest separations that we have. Mr. ThoRNToN. I hope that you find it. l)r. GREGORY. It is not true to say that a pipeline system for natural gas will leak hydrogen. Dr. THORNTON. Thank you, Mr. Chairman. Mr. MCCORMACK. Mr. Dodd. Mr. Dorm. Thank you, Mr. Chairman. I have, really, just one ques- tion. I apologize to you for being late. On page 8 of your testimony, and I am now referring to Mr. Law, you talk about hydrogen being produced from coal, that this may be an important factor in the transmission, and so on; that this deserves further examination. What is Northeast TJtilities doing to utilize coal, given the current energy crunch-that is, considering the situation in the northeast with our problems of petroleum? It has been stated on numerous occasions that, in the northeast, there is the ability to trans- fer from petroleum to coal readily as an energy source. I was curious about that statement, as to the whole question of hydrogen, and what particular problems you may be having in this regard as a utility? Mr. LAW. Northeast Utilities is participating now with the Office of Coal Research. This is now called ERDA, however. This is in re- gard to the building of a pilot coal gasification device, using the molten carbonate scheme with the Atomics International Division of Rock- well International. We expect, next year, to have the pilot plant in operation. We would then ~like to invite you to come down and see it in operation. Mr. DODD. It seems that-and again, I beg ignorance on this-but I do get the impression from the so-called experts that the transfer to coal is something that does not have to go through a pilot program to PAGENO="0228" 222 be utilized by our utilities. Is that a fact or are we not capable at this time of doing so? Mr. LAW. We are capable of doing this today, but not at the efficiency and as clean as we want to. The Electric Power Research Institute has a large program in the gasification and the liquefaction of coal. It is the low Btu gasification of coal for use as a clean fuel in our burners. The gas industry has a. very large program in the high Btu gasification of coal. Between the two, we hope. in the future, to be able to come out with a clean fuel from coal that will be able to be used in Connecticut. I want to repeat what I said in my testimony about the efficiency of gasification of coal. If you can get an external source of hydrogen, this increases the amount of gas from the same amount of coal by about 21/2 times. If you add to that an external source of heat so that you don't have to burn the coal in order to provide heat for the process, like a nuclear source of heat, you can increase the amount of gas even more. I think it is five or more times as much gas from the same amount of coal. I think that both of these areas deserve a great deal of thought. Mr. DODD. Thank you. Mr. LAW. Yes, sir. Mr. DODD. That is all I have. Mr. MOCORMACK. We have about 2 minutes. Mr. Hechler, you may proceed. Mr. HECHLER. First, I want to thank my colleague from Connecticut for the great plus that he made for coal. I do appreciate that. I assume that. von meant not only synthetics, but that. you meant the present. conversion. Mr. DODD. Yes. * Mr. HECULER. Your answers were mainly in terms of the synthetics? Mr. LAW. Yes. Mr. HECHLER. I would like to press for the utilization of our most abundant fuel resource in the northeast area, as well as in other areas of the country. In the testimony that you gave, you just raised the corner of the tent as t.o the effects of hydrogen use, the environmental effects of the use of hydrogen. I will quote: While hydrogen is generally thought to be environmentally benign, environS mental issues associated with all phases of hydrogen energy systems need careful and continuous evaluation. Can you please elaborate on what the environmental effects of hy- drogen are. that you called attention to. and what we have to do about this, a.nd in what direction we have to proceed, Mr. Law.? Mr. LAW. I will let my colleague answer. But I would like to say, to start with, sir. that I am very conscious of the fact that, if we started with the automobile today and tried to get permission to put gasoline in a tank a.nd carry it on the street. well, in today's environmental climate, we would have a. heck of a. job getting this approved. Mr. HEcTILER. Can you say something briefly about the environment? Mr. LOTKER. The environmental effects are principally associated with the hydrogen production sources and production of nitrogen ox- ides from burning hydrogen in the a.ir. Mr. HECHLER. Thank you. Mr. LOTKER. Yes, sir. PAGENO="0229" 223 Mr. LAW. Thank you, Mr. Chairman. Mr. MCCORMAGK. Thank you. Mr. Frey, do you have questions? Mr. FREY. Mr. Chairman, I will be brief `and to the point. Do you think that with the tremendous potential that we have, that this is reflected at all in the administration's budget or the EIRDA budget, from your standpoint, or from an industry standpoint? Are you satis- fied with the amounts going into research? Mr. LOTKER. It is hard to identify the specific amounts. I second Dr. Gregory's statement that it would be nice if hydrogen truly found a home in ERDA where one could better coordinate the overall effort. Dr. GREGORY. I believe that the budget on hydrogen was about $8 million. I can't really identify where that is being spent. There is no place where you can see at a glance where money is being spent on hydrogen. Mr. FREY. Could you please submit for the record or let us know the amount that industry is spending? Have you any feel what industry is putting into this? Dr. GREGORY. It is hard to get an accurate figure on this, sir. Mi'. FREY. What about a ballpark figure? Dr. GREGORY. In one of my attachments to my testimony, there is a survey of what we believe is going on now on worldwide basis. Mr. FREY. I would like to say this. We talk about the potential and the things that we can do. We are spending $8 or $10 million for this. We are, at the same time, spending billions for people to pick up leaves. It does not make a lot of sense. Mr. LAW. If you include the fuel cells, there is a large amount of research going on in this area. Mr. MCCORMACK. Thank you, gentlemen. I want to conclude at this time by saying that, as to ERDA, NASA and the Defense Department, and as to those in industry, one of the interesting things is that we are beginning to focus on the problem, to get organized and to get started. I think this is healthy. We want to push along very aggressively and to maintain our communications throughout the entire community. We will clearly be putting a great deal more emphasis on hydrogen in the future. Thank you for appearing. Mr. LAW. Thank you, Mr. Chairman, for the opportunity to testify. Dr. GREGORY. Yes, thank you. Mr. MCCORMAOK. We stand adjourned. [Whereupon, at 9:25 a.m., the subcommittee adjourned.] PAGENO="0230" PAGENO="0231" 225 APPENDIX I STATEMENTS FOR THE RECORD PAGENO="0232" 226 PAGENO="0233" 227 LOCKRKED-CAIJFORNIA COMPANY A DIVISION OF LOCKHEED AIRCRAFT CORPORATION BURBANK, CALIFORNIA 91520 FS/75-21-1123 3 September 1975 The Honorable Mike McCormack, Chairman Subcommittee on Energy Research, Developnent and Demonstration Suite 2321, Rayburn House Office Building Washington, D.C. 20515 Reference: Letter from. Congressman Mike McCorrnack, Chairman, to G. Daniel Brewer, Lockheed.. California Company, dated August 1~, 1975. Dear Congressman McCormack: The reference letter invited comments on hydrogen, including suggestions for potential uses. This is to present some views concerning the potential of using liquid hydrogen as fuel for transport aircraft in the future. Testimony presented to the Subcommittee on Aeronautics and Space Technology of the (then) House Committee on Science and Astro~. nautics, by Gordon Sim of Lockheed on 22 February l971~, outlined some significant background relative to the potential use of hydrogen as a fuel for transport aircraft. Since that statement was prepared continuing studies have confirmed the advantages of using hydrogen which were recognized early as possible of attain.. ment. In addition, other aspects have been explored which further reinforce our conclusion that liquid hydrogen should be seriously considered, along with synthetic Jet A made from coal or oil shale, as a potential answer to the question of what fuel should be used in transport aircraft at that time in our future when fuel de- rived from petroleum becomes too costly or is simply not generally available. A discussion of the subject is presented in the paper `~fl~rdrogen Fueled Transport Aircraft11, submitted herewith as Enclosure A. This paper was written for presentation at the recent U.S.~Japan Hydrogen Energy Seminar, held in Tokyo on July 20-.23, 1975, under PAGENO="0234" 228 the co-sponsorship of the U.S. National Science Foundation and Japants Society for the Advancement of Science. Following is a summary of the arguments developed: o Commercial transport aircraft require a fuel which is available worldwide at a reasonable price. This is crucially important not only to the air carriers, but also to the U.S. aircraft industry, prime contractors as well as suppliers, who manufactured 86% of the commercial jet aircraft currently in use by airlines of the free world. o Conventional Jet A fuel, derived from petroleum, is marginally acceptable in both cost and universal availability at the present time due to the fact the major sources of crude oil are controlled by a small, well organized group of nations. Indications are that the supply situation will get worse in the future as world reserves of crude oil are depleted. o synthetic Jet A fuel can be manufactured from coal, oil shale, and! or tar sands but the reserves of these fossil materials are neither unlimited nor universally available. Further, it may be seriously questioned whether these fossil materials should not better be reserved for other uses. o Hydrogen can be manufactured from water using almost any available source of energy, e.g., nuclear, solar, geothermal, hydro, or waste products, in addition to any use which might be made of the conventional fossil fuels. It can therefore be universally avail- able at a reasonably constant price, without threat of control by any cartel. o As an aircraft fuel, hydrogen has been shown to provide significant advantages in designs which are both feasible and practical. Long range hydrogen-fueled subsonic as well as supersonic aircraft can be lighter, quieter, use smaller engines, are able to operate from shorter runways, minimize pollution of the environment, and expend less energy in performing their missions than equivalent designs fueled with Jet A. In addition, the hydrogen-fueled aircraft are physically smaller in wing span and area, but they have larger fuselages. Hydrogen-fueled supersonic aircraft would produce sonic boom overpressures markedly lower than conventionally fueled designs. Airline turn-around schedules can be essentially the same with either fuel and there is evidence that passenger safety from fire hazard will be at least as good with hydrogen as it is with Jet A. It is recognized that changing the air transportation industry to a new fuel will be a difficult and costly experience. It will be particularly so in the case of liquid hydrogen because of the need to develop a new infra- structure to manufacture, liquefy, and produce equipment to handle the fuel. The need to coordinate the choice of a new fuel with the major nations of PAGENO="0235" 229 the world will require diplomatic and legislativ6 involvement, as well as technical and industrial cooperation. For these reasons, selection of a fuel for use in future commercial transport aircraft must be very carefully consider.. ed and the choice between hydrogen and synthetic Jet A based on full and complete information about the characteristics, long term availability, and general usefulness of both fuels. To provide such data about liquid hydrogen the technology development and demonstration summarized in Figure 1 has been recommended to NASA in NASA CR-l32559, "Final Report: Study of the Application of Hydrogen Fuel to Long- Range Subsonic Transport Aircraft," dated January 1975. It is felt the flight demonstration, item 16, in conjunction with the airport fuel handling demon- stration, item 17, will be particularly valuable in developing information about a practical basis for handling the cryogenic fuel and establishing confidence that hydrogen can be used safely in airline-type operations. Thank you for the opportunity to submit our views and recommendations to your committee. We will be very happy to answer any questions or provide further data as required. Sincerely yours, - LOCKEt~g~-CALIFORNIA CONPANY G. Daniel Brewer Manager, Hydrogen Studies GDB:bw Ends. PAGENO="0236" SUBSONIC LH2 TRANSPORT AIRCRAFT STUDIES 1. AIRCRAFT DESIGN STUDIES 2. TANK AND INSULATION DESIGN 3. AIRCRAFT FUEL SYSTEM DESIGN 4. AIRPORT FUE.L SUPPLY SYSTEM ANALYSIS 5. AIRFRAME STRUCTURAL CONCEPTS STUDY 6. ADVANCED ENGINE DESIGN STUDY 7. OPERATIONS ANO MAINTENANCE PROCEDURES ANALYSIS 8. AIRPORT/AIRPLANE FACI LITIES REQUIREMENTS 9. LH~ USE INITIATION STUDY 10. FUEL HAZARDS ANALYSIS EXPERIMENTAL DEVELOPMENT FUEL SYSTEM TECHNOLOGY DEVELOPMENT ENGINE TECHNOLOGY DEVELOPMENT 13. MATERIALS DEVELOPMENT 14. CRASH SAFETY COMPARISON 15. FIRE HAZARD COMPARISON FLIGHT OPERATIONS 16. FLIGHT DEMONSTRATION PROGRAM 17. AIRPORT FUEL-HANDLING DEMONSTRATION PROJECT FS/'i~-21 .1173 Figure 1 11. 12. CALENDAR YEARS - - PROGRAM ~zz~1 77 I 78 [79 L~ 80 61 COST ($106) as c: .~ t .1 t:~= ~ ~}=:J~T_~l_._~,) 1.0 .4 8.00 I :~L~-~0 .~ I L-L~ 4.0 50 ~ ~ 57.0 75.8 ~TOT1L Figure 1. Technology Development Program PAGENO="0237" 231 Enclosure A ?S/75~2i..ll23 HYDROGEN FUELED TRANSPORT AIRCRAFT G.D. Brewer Lockheed-California Company Burbank, California, U.S.A. ABSTRACT The air transport industry is particularly vulnerable to the cost and avail- ability of fuel. In tines of fuel shortages national priorities must favor more basic needs, airline economics is extremely sensitive to cost of fuel, current aviation fuel can be produced as only a small fraction of the crude oil processed, and in order to be effective commercial trans- port aircraft require a fuel which is available worldwide. Hydrogen is found to provide an attractive solution to these problems. The results of studies performed to investigate the feasibility, practicability, and potential advantages/disadvantages of using liquid hydrogen as fuel in both subsonic and supersonic commercial transport aircraft for initial operation in the 1990-2000 time period are presented and discussed. ThTRODUCTION Although there are still disbelievers, it is gradually becoming more widely appreciated that the world's supply of petroleum is limited and that the end is in sight for that fraction which can be economically recovered [Reference 1]. It is also generally agreed that the availability and cost of petroleum-derived fuel will continue to become less and less attractive in coming years. Shortages in the past have been due largely to the embargo imposed by the Organization of Petroleum Exporting Countries (OPEC), beginning in October 1973 for military and political purposes, and subsequently to control of production rates and prices for economic advantage. In the future, shortages and higher prices will be due not only to continued inter- national political and economic pressures, but also, and to an ever- increasing degree, to the growing imbalance between supply and demand as t.he resource is depleted. The air transportation industry is particularly vulnerable to the effects of both uncertainty of supply and rising cost of fuel. This paper will con- sider some of the factors which lead to this vulnerability; namely, * the effect of national priorities on fuel usage, * * the sensitivity of airline economics to fuel costs, * the relatively small fraction of the crude oil barrel which can be converted to aviation quality fuel, and * the need for worldwide availability of a uniform product for air- craft fuel. (Presented at U.~.-Japan Hydrogen Energy Seminar, Tokyo, Japan, July 20-23, 1975) 1 PAGENO="0238" 232 In addition, the benefits to be gained by switching to liquid hydrogen as the fuel in advanced design transport aircraft will be reviewed. EFFECT OF NATIONAL PPIORITI~S In times of fuel shortage, national priorities demand that the population be able to heat their homes, cook their food, and continue to work at the jobs which produce the goods and services necessary to keep the econonw functioning. Fuel normally used for nonessential purposes is restricted, either by persua- tion and voluntary conservation, or by imposition of controls. Accordingly, fuel allotments go first to meet essential residential, utility, agricultural, and industrial needs. Next, fuel is provided for transportation so workers can get to their jobs and freight can be moved. In contrast, fuel normally used for recreation, pleasure, nonessential travel and the like, is severely curtailed. The fuel allocations which were made in the United States at the time of the OPEC embargo in 1973 roughly followed this pattern. Since less fuel was available for use reductions were made in all sectors of the econon~r, however, the air transportation industry was hit particularly hard. In order to achieve maximum revenue from the fuel they were able to purchase, the airlines reviewed their equipment needs and retired from service their less efficient aircraft, as well as those aircraft which no longer matched their reduced traffic requirements. It is accurate to point out that not all of the airline's difficulties due to lack of traffic were a direct result of the national priorities which cut back on the amount of fuel available for their use. An important additional factor was the sag in the general economy which reduced the number of potential travelers so that even when fuel again became available, the airline's business did not immediately improve. Nevertheless, it is important to realize that directly or indirectly national priorities are such that the air transportation industry is subject to being more adversely affected than most other fuel users in tines of shortages. SENSITIVITY OF AIRLINE ECONOMICS TO FUEL PRIC~E Airline economics is very sensitive to fuel prices because aircraft require significantly more ener~r to do a given amount of work than do other modes of transportation. As shown in Table 1, a modern, conventionally-fueled commercial aircraft cruising at Mach 0.8 (610 mph = 273 m/s) requires over five times the ener~r per passenger mile needed by a conventional train traveling at 60 mph (26.8 mIs); 14.33 times the ener~r used by a diesel-powered highway bus traveling at the same speed; 2.5 tines the ener~r consumed by the famed Bullet Train of Japan traveling at 125 mph (56 m/s), and 2.1414 times as much as a subcompact car carrying, for purposes of this comparison at a load factor of 60 percent, 2.4 people at 60 mph (26.8 m/s). 2 PAGENO="0239" 233 TABLE 1. TYPICAL ENERGY UTILIZATION OF TRANSPORTATION SYSTEMS [Data from Reference 2] Transportation System Speed (mps) Energy Utilization* Btu/PAX mi Metroliner Train Highway Bus Japan Bullet Train Subcompact Car Current Aircraft 60 60 125 60 610 895 lOI~5 1810 1860 1~51~O *At 60 percent Load Factor This is not an indictment against commercial aircraft; there are not many of us who would willingly give up the pleasure, convenience, and, indeed, virtual necessity of high speed travel in this competitive era for a return to the slower modes, particularly for long distances. Rather, these comparisons are made to show that as fuel prices rise, airline costs must rise significantly faster than those of other transportation systems. For instance, in 1973, when U.S. domestic trunk airlines paid an average of 12.5~/gal. for aviation fuel (Jet A), typically 10.7 percent of the total operating cost (TOC) was for fuel [Reference 3]. By contrast, in about the same period only 5.5 percent of the operating cost of a conventional intercity, diesel-powered bus was far fuel. The effect of increases in fuel price on operating cost for both of these transportation modes is illustrated in Figure 1. The fraction of airline TOC due to fuel cost increases to over 32 percent in two successive doublings of fuel price. Starting from a lower base level, the fuel fraction of bus operating cost is less drastically affected by the same percentage increase in fuel price. The inevitable result will be a reassessment of choice on the part of the air- traveling public as fuel prices rise, undoubtedly driving some to decide not to travel at all, or alternatively, to pick a more economical mode. In any event, the result will be loss of business for the airlines. A nearly ideaJ. solution to this dilemma would be for commercial transport aircraft to use a fuel which could be manufactured from a material commonly available through- out the world using ener~r from any of several sources, so that the fuel would be invulnerable to attempts to control either its price or its availability. L~M PRODUCIBILITY OF 3M A FUEL Another factor which adversely affects the air transportation industry relative to its continued long term usage of petroleum-base fuel is the fact that only a relatively small percentage of a barrel of crude oil can be con- verted to aviation quality fuel. Table 2 shows the products typically derived from a barrel of crude oil at the present time in the United States. Industry refineries are currently tuned to maximize production of gasoline. Only about five percent of the barrel is converted to commercial aviation fuel specifica- tions (Jet A or Jet A-l). The right hand column in the table lists the per- centages of the various products which could be derived if the refineries were modified and retuned to na.ximize production of aviation fuel instead of gasoline. In this case 17 percent of the barrel could be converted to the 3 PAGENO="0240" 234 3.6 3.2 TOTAL OPERATING COST (~ISEAT MI.)2~ Figure 1. Effect of Fuel Price on Operating Cost TABLE 2. PRODUCTS DERIVED FROM A BARREL OF CRUDE OIL IN THE UNITED STATES [From Reference 14] Product Refinery Practices (Percent) Present* (To Maximize Production of Motor Fuel) Possible (To Maximize Production of Jet A-Type Fuel) Light Ends (Propane, Butane, etc.) Motor Fuel (Gasoline) Kerosene (Jet A and Jet A-l) Other Distillates (Diesel Fuel, etc.) Other Products (Oil, Grease, Asphalt) FuelOil (Bunker Fuels) 3 147 5 ~ 26 13 6 5 18 17 20 26 lIt *Based on average industry-wide runs. 4.4 4.0 "liz' BODY. TURBOFAN ~RCRA~ - , ~ -~ DIESEL-POWERED HIGHWAY BUS -~ ~1T____1_~ - .~- 2.4 2.0 1.6 0 10 20 30 40 50 FUEL PRICE (i/GAL) 60 70 14 PAGENO="0241" 235 Jet A specification, but gasoline and diesel fuel production would be signifi- cantly reduced. Such a change could only be accommodated if a substitute fuel wascreated for automobiles, trucks, farm equipment, etc., a much greater undertaking than would be faced if an alternate fuel was manufactured for com- mercial aircraft. Another option which is currently being explored to permit continued use of liquid hydrocarbon-type fuel for commercial aircraft is to relax the fuel specification to permit acceptance of a wider band of distillation products. This includes, of course, fuels which might be produced from tar sands, oil shale, and coal. It is recognized that there are a number of serious problems ~ihich must be faced in aircraft engine and fuel system design if the fuel specification is relaxed. The specification for commercial jet fuel was gradually evolved over a period of years in a process of refinement to a most desirable product. Modification of the specification will inevitably involve penalties in performance, weight, life, cost, emission levels, and maintenance of aircraft engines and fuel systems, and even in aircraft safety. For in- stance, the U.S. Air Force currently uses fuel produced to the JP-14 specifica- tion, a wide-cut gasoline product which has a lower flash point than Jet A (broadly categorized as kerosene). About )4O percent of a crude oil barrel can be distilled to JP-)4; however, there is increased fire hazard. Commercial airlines are not now permitted to use Jp_)4 because of this. The U.S. Navy uses fuel made to the JP-5 specification which is very similar to commercial Jet A, for reasons of increased safety on shipboard. Recently, it was announced that the Air Force is making plans to change their fuel specifica- tion to Jp-8, a product which presumably will have a higher flash point. the following examples of how deviations from the jet fuel specification can affect aircraft engines and their components are summarized from a paper given by F. Jaarsma at the 197)4 AGARD Annual Meeting in Paris on 26 September 197)4 [Reference 5]: * Increased amounts of aromatic hydrocarbons result in - Lower heat of combustion - Carbon formation during combustion; leads to greater heat radia- tion and higher metal temperatures which adversely affects per- formance, life, and maintenance requirements of combustor and turbine blades. Causes smoke and increased emission of pollutants. - High hygroscopicity - Problems with seals (causes rubber to swell) * Higher volatility limits will introduce pump cavitation problems. In addition it will either require tanks designed to withstand higher pressures (hence more weight), or will cause greater fuel loss due to vaporization. * Relaxed limits on thermal stability can result in decomposition of the fuels as well as pump cavitation problems. 5 62-332 0 - 76 - 16 PAGENO="0242" 236 * Relaxed limits on contaminants such as sulfur - greatly increases corrosion of the fuel system, even trace amounts stimulate carbon depcsition in the corobustor. sulfur, sodium, chlorine, and vanadium - all lead to increased problems of hot corrosion of turbine blades. The conclusion is that because of detrimental effects it is not likely there will be a sigmif5 cant relaxation in the commercial jet fuel specification; therefore, no great increase in the percentage of jet fuel produced per bar- rel of crude should be expected. It is further concluded that because fuel produced from syncrude, derived from coal, can be expected to contain larger amounts of aromatic hydrocarbons, performance of engines designed to use that fuel will be severely limited in improvement potential. NEED FOR WORLDWIDE AVAILABILITY The fourth factor involved in the unhealthy vulnerability of the air trans- port industry to cost and availability of fuel is the need for the fuel to be available worldwide. Commercial aircraft are designed to use a specified fuel in the most efficient manner possible. Every reasonable effort is made ~n the design of such aircraft to eliminate excess weight because there is a one-to-one relationship between inert weight and payload. For every pound of inert (non-fuel or non-payload) weight added to an aircraft, the allow- able payload must be reduced one pound on a maximum payload/maximum range flight. From another point of view, a modern commercial transport aircraft has a sensitivity to inert weight such that on a maximum payload/maximum range flight, every 100 pounds of extra weight carried by the aircraft reduces its maximum range capability by about 3.6 n.mi. If such an aircraft was required to incorporate a second and completely separate fuel system, possibly with some engine modification also, to permit its use by any air- line in the world and provide assurance that at least one of the fuels would be available at every refueling stop, the inert weight represented by the backup fuel system could impose a severe reduction in earning capability of the airplane. At best it would be an unwelcome financial burden on the operating airlines. Alternatively, the aircraft could be designed to incorporate one or the other of the fuel systems and be sold with whichever is specified by the buyer as his preference. This option has the obvious disadvantages that a) the sell- ing price of the aircraft would be higher than if a single, uniform fuel was available worldwide; b) the individual aircraft would be unsuited to use in those areas of the world where its particular type of fuel was not available, thus limiting its route potential, and c) its resale potential would be limited. PLANNING FOR ALTERNATIVES It is clear from all this that commercial transport aircraft are not flexible insofar as fuel is concerned, and that they are particularly vulnerable to price increases and lack of availability of the fuel for which they are 6 PAGENO="0243" 237 designed. The question is, in view of the grim outlook for the future of petroleum-based fuel, what are the alternatives facing the air transport industry? What other fuels offer more promise and what are the criteria that should serve as a guide in making the choice of a fuel for the future? The design and development cycle for large commercial transport aircraft of ad- vanced design is approximately 10 years. The normal design life expectancy for aircraft of this type is about 20 years. Assuming a production cycle of 10 years, any new commercial transport aircraft whose design is started in 1916, for example, would normally be in service from 1986 through 2016, as a minimum. It is not realistic to assume that current quality fuel will con- tinue to be generally available around the world at economically acceptable prices that far into the future. The time has arrived for planning the future of commercial aviation! Following are some questions which require serious consideration in order that a logical selection can be made of the alternate fuel that will best serve the long range purposes of the industry: * What is the preferred fuel for commercial aviation from the points of view of cost, performance, emissions, energy, noise, long range availability? * How can the transition to a new fuel be implemented without serious disruption of existing commercial airline service, or undue financial burden on the airlines? * How much will it cost to provide facilities to store and handle the new fuel at airports, and how should it be capitalized? * Recognizing the international aspects of the problem, the choice of the new fuel requires cooperation among the principal nations. How can this best be accomplished? Some aspects of the first question are addressed in the remaining sections of this paper. This seminar is one of the initial steps to be taken in the direction of resolving the last question. Hopefully, this brave beginning will lead to other, more comprehensive meetings involving active participa- tion of the other principal nations of the world which are affected by the cost and availability of efficient air transportation. Plans are being made in the United States to institute studies which will begin to provide answers for the remaining two questions. Much remains to be done. HYDROGEN AS AN AIRCRAFT FUEL Several surveys have been made to determine which fuels are the most likely candidates to replace petroleum-based Jet A as the fuel for commercial trans- port aircraft in the future [References 6 and 1]. Table 3, taken from [Reference 6], lists the fuels usually considered as major candidates, to- gether with some of their nominal properties. Jet A fuel is included for comparison. Ideally, the selected fuel would * be producible at low cost from a resource which is continuously re- plenished in a short time cycle, 7 PAGENO="0244" 238 TABLE 3. PROPERTIES OF SOME CANDIDATE FUELS Jet A Fuel Methane Ethyl Alcohol Methyl Alcohol Pmmonia Hydrogen Nominal Composition CH194 CH4 C2H5OH CH3OH NH3 H2 Molecular Weight =120 16.04 46.06 32.04 17.03 2.016 Heat of Combustion (Btu/pound) 18,400 21,120 12,800 8600 8000 ~ 51,590 Liquid Density (Lb/Ft3 at 50°F) 47 26.5* 51 49.7 42.6* 4,43* Boiling Point (°Fatl Atmosphere) 400 to 550 -258 174 148 -28 -423 Freezing Point (°F) -58 -296 -175 -144 ~ -108 -434 Specific Heat (Btu/Lb0F) o.48 0.822 0.618 0.61 1.047 2.22 Heat of Vaporization (Btu/Lb) 105-110 250 367 474 589 193 *At Boiling Point * be capable of efficiently satisfying many needs (not just aviation), * require minimum change in existing equipment and procedures to pro- vide effective service, and * offer minimum hazard to the environment either during its production, from spills during transport or storage, or during use, i.e., from combustion. Analysis of the candidate fuels listed quickly leads one to hydrogen as one of the preferences. Synthetic Jet A, produced from coal, tar sands, or oil shale, must also be considered a viable alternative to petroleum-based Jet A because of the ease with which it can be substituted in the economy for the conventional product. The other candidates are considerably less attractive. Methane is a more energetic fuel than Jet A by about 15 percent, but it has the disadvantages of being a cryogenic liquid and having low density, although to a lesser degree than hydrogen. Studies have shown that methane could be an attractive fuel, particularly for supersonic aircraft [Reference 8]; how- ever, it is considerably less energetic than hydrogen and therefore is not so 8 PAGENO="0245" 239 advantageous. The alcohols and ammonia do not produce enough energy per unit weight to be considered seriously for weight-sensitive applications like air- craft and surface effect vehicles. They could more logically be considered candidates for use in vehicles for surface transportation, e.g., autos, trucks, and buses, where weight is not so critical. Several of the papers presented at this seminar have discussed methods for producing hydrogen. From these it is clear that hydrogen meets many of the criteria mentioned above as characteristics desired for a fuel of the future. It is producible in a variety of processes, using any of several sources of energy, from a resource (water) which is continuously replenished in a short time cycle; it is capable of efficiently satisfying many needs - in addition to those of aviation; it offers minimum hazard to the environment. On the other hand, hydrogen falls short of being ideal for aircraft in that 1) it requires expenditure of large amounts of energy, both to split the water molecule and to then reduce the energy of the hydrogen molecule to achieve liquefaction; 2) its cost is a strong function of the source of the energy used and, in most locations around the world, would be somewhat higher than that of synthetic Jet A fuel; and 3) the change in equipment and procedures required for effective service is not minimal. In spite of these disadvantages, recognition of its very attractive potential advantages has led to serious consideration of the possibility of using liquid hydrogen (LR2) as a fuel for commercial transport aircraft. Starting in early 1972, some preliminary analyses were initiated at Lockheed-California Company. Both subsonic and supersonic aircraft designs were examined. The results were sufficiently encouraging that in mid-1973, NASA-Ames Research Center awarded a contract to Lockheed for a more formal analysis of the potential of using the fuel in advanced designs of supersonic transport aircraft. Early in l97~4, NASA-Langley Research Center awarded Lockheed a similar contract to investigate use of LH2 in subsonic transport aircraft. The objectives of both studies were broadly the same. They were to * assess the feasibility of using hydrogen fuel in commercial trans- port aircraft * determine its advantages and/or disadvantages, relative to conven- tional Jet A fuel * identify problems and technology requirements associated with use of LH2 * outline a plan for development of the required technology. The basic guidelines which were common to both studies are listed in Table ~. [References 9 and 10] are, respectively, the final reports of each of these investigations. The following discussion presents a summary of the results, including a statement of conclusions which were reached regarding the poten- tial of liquid hydrogen as the fuel for commercial transport aircraft of the future. 9 PAGENO="0246" 240 TABLE l~. BASIC GUIDELINES Fuel - Liquid Hydrogen Assumed Available at Airports Initial Operational Capability -~ 1990 - 1995 Advanced Technologies * Control Configured Aircraft * Conposite Materials * Configuration: Subsonic - Supercritical Aerodynamics Supersonic - NASA Arrow Wing * 1985 State-of-the-Art Propulsion Direct Operating Costs * 1967 ATA Equations * 1973 Dollars Design LH2 and Jet A Fueled Aircraft to Perform Same Mission, Based on Same Operating Requirements: * Runway Length * Noise Limitation * Fuel Reserves * Certification Standards SUPERSONIC TRANSPORT AIRCRAFT Considering first the supersonic transport aircraft application for LH2 fuel, Figure 2 is a pictorial representation of the Mach 2.7 cruise speed vehicle. It is designed to carry 231~ passengers ~42OO nmi. Some of its design features are illustrated in the interior arrangement drawing~of Figure 3. The passen- gers are located in the center section of the fuselage directly over the wing. They are seated in a double deck arrangement which, as sho~m in the inset view, Section A-A, has three seats on either side of a central aisle on each deck, for a total of 12 seats per row. Liquid hydrogen fuel is con- tained in tanks located both forward and aft of the passenger compartment. The double lobe cross-section of the fuselage extends through both tank compartments. A unique feature of this design is that there is no provision for physical access between the passenger compartment and the flight station. Although this is a departure from current practice, consultation with airli±ie representatives concerning its acceptability produced no strong arguments requiring such access. The aircraft design using this passenger/tankage arrangement was adopted only after a lengthy parametric evaluation of many alternate aircraft configurations. The design selected was found to offer 10 PAGENO="0247" H H Figure 2. Mach 2.7 ~2 Supersonic Transpo~ PAGENO="0248" Figure 3. Interior Arrangement, LH2 Supersonic Transport PAGENO="0249" 243 significant weight, performance, and cost advantages. Non-access between flight station and passengers is not necessarily advocated as an advantage, but neither is it regarded as a significant disadvantage in commercial transport aircraft. Aside from the double-lobe fuselage and the location of hydrogen fuel tanks fore and aft of the passenger compartment the aircraft design is conven- tional and quite similar to that of its equivalent design using Jet. A fuel. The wing has the NASA-developed arrow wing planform. It has subsonic lead- ing edges equipped with Krueger leading edge flaps on the outboard panels. Along the trailing edge there are conventional flaps and spoilers inboard; flaperons, which function as both flaps and ailerons, are located between the inboard engine and the wing vertical surface; and there are conventional ailerons on the outboard panels for low speed control. The visor nose tips down to provide the crew with good visibility for takeoff and landing. The all-moving horizontal stabilizer has a geared elevator and the all-moving vertical tail has a geared rudder. Tail surfaces were sized using the sane tail volume coefficient as previously established for the conventionally- fueled counterpart aircraft. Four turbofan engines with axisymmetric inlets are mounted beneath the wiiig with their exhaust ducts extending just aft of the wing trailing edges. Landing gear design is conventional. A summary of the characteristics of the selected design of LH2-fueled Mach 2.7 supersonic transport aircraft is presented in Table 5, along with corresponding data for an equivalent Jet A-fueled aircraft. The Jet A aircraft design data is from a study [Reference 11] also conducted by Lockheed but for NASA-Langley Research Center. The sane Advanced Design organization at Lockheed-California Company in Burbank performed both investigations so there was ideal opportunity for matcl'ing design criteria in non-hydrogen related elements, and in achieving equivalency in mission per formance. The column in the table labeled `Factor" provides a numerical evaluation of the differences between the LH2 and the Jet A aircraft designs for each of the parameters listed. As noted, the evaluations are presented in terms of values for the Jet A design relative to those for the LH2-fueled aircraft. It may be seen that the LH2-fueled aircraft offers significant advantage in almost every item listed. For example, the conventionally fueled (Jet A) aircraft weighs twice as much at takeoff, its empty weight is 39 percent higher, and it requires four times the fuel weight to fly the equivalent mission. It needs engines having almost twice the thrust of those on the LH2-fueled design. Physically, the L112-fueled aircraft has a much smaller wing, both in area and in span, however its fuselage is significantly larger. This is the result of carrying the hydrogen fuel in the fuselage, rather than in the wing as is the case with the conventionally fueled design. The low den- sity (~.b lb/ft3) of LH2, and the fact it is a cryogenic liquid (it lique- fies at _b230F at one atmosphere pressure), require that a) the fuel tanks will be relatively large, and b) they must be of a shape to minimize surface-to-volume ratio in order to avoid excessive penalties in weight 13 PAGENO="0250" 244 TABLE 5. COMPARISON: JET A VS LB2 SUPERSONIC TRARSPORT AIRCRA~'T (2314 FAX, 14200 N.MI., H 2.7) . LH2 Jet A fJ k Factor et A. LB2 Gross Weight Lb 368,000 750,000 2.014 Operatin~ Empty Weight Lb 223,100 309,700 1.39 Block Fuel Weight Lb 81,14140 326,000 Thrust per Engine Lb 146,000 89,500 1.914 Wing Area Ft2 6880 10,822 1.58 Span Ft 105.6 132.5 1.25 Fuselage Length Ft 328 297 0.91 Height Ft 37.5 314.8 0.93 LID (Cruise) 6.99 8.5 1.21 SFC (Cruise) -i/Lb 0.561 1.51 2.69 Aircraft Price $106 148.0 67.3 1.140 Energy Utilization Btu Seat n.mi. 142714 6102 1.143 of insulation, or in weight of fuel lost through boiloff. These require- ments are basically incompatible with carrying LH2 in the wing of the sub- ject aircraft. They are the basis for the considerations which led to the geometric design and p~iysical location of the tanks for the LH2-fueled air- plane shown in Figure 3. A graphical comparison of the relative sizes of the LH2 and the Jet A-fueled supersonic aircraft designs is presented in Figure 4. The next two parameters listed in Table 5 are the operating characteristics which account for the principle differences between the two airplane designs. Specific fuel consumption (SFC) is a measure of the energy con- tent of a fuel, and of the effectiveness of an aircraft engine in convert- ing that energy to useful thrust. It is measured in lb/hr of fuel flow rate divided by thrust output achieved by the engine during various con- ditions of operation. In the table, the values of SFC are shown for the speed and altitude representing average values during uruise. As seen in the "Factor" column, the hydrogen-fueled airplane has an overwhelming advantage since the Jet A-fueled design will consume 2.69 more pounds of fuel per hour per pound of thrust to deliver a given thrust level. The difference is basically accounted for by comparing the heating values of the fuels. Hydrogen has a heat of combustion of 51,590 Btu/lb, whereas Jet A fuel is only 18,1400 Btu/lb. 114 PAGENO="0251" 245 H.0 ______ I-s 297' . a-I JETA Figure ~. Size Comparison: vs Jet A Supersonic Transport Aircraft 15 PAGENO="0252" 246 On the other hand, because the LH2-fueled airplane must have a larger fuselage to contain the low density, cryogenic fuel, it has a less aero- dynamically efficient shape and suffers from a lower lift-to-drag ratio (LID). The factor of 1.21 listed in the table means that for an equiva- lent weight airplane the Jet A design would have 21 percent less drag and would therefore require less thrust to maintain cruise speed. A lower thrust level would mean a smaller fuel flow rate, the effect tending to compensate somewhat for the severe disadvantage in SFC observed for the Jet A-fueled airplane. The fact that the LH2 aircraft design is lighter to start with, however, means there is less weight to lift and accelerate to cruise condition, thereby minimizing the handicap of its lower L/D. The cumulative effect of all of these factors is shown in the comparison of the weight of fuel required by each aircraft to carry the specified payload the required distance at the desired speed. The aircraft prices listed in Table 5 reflect a significant advantage for the hydrogen-fueled design. Estimation of the price of an aircraft is a function of a number of parameters, the most dominant of which are its gross weight and the thrust of its engines. Both of these parameters are considerably lower for the LH2 design, so that even using the higher cost factors which account for the anticipated increased complexity of that design, there was a net saving. It should be noted that the cost for development of the LH2 design, estimated at $3.32 billion, does not include cost for development of the technology required to start formal design of a commercial transport aircraft. However, this technology development is estimated to be only about two percent of the total aircraft/engine devel- opment cost so the addition, amortized over the 15 year lifetime of an aircraft, would be negligible. Energy utilization, as defined here for purposes of comparing the relative efficiencies of aircraft designed to use the two different fuels, is the amount of energy consumed in transporting the design payload the specified range. As noted, the supersonic transport aircraft whose characteristics are shown in Table 5, carry 2314 passengers plus full cargo (a total pay- load of 149,000 pounds) 4200 nmi. With the LH2-fueled aircraft this requires 14212 Btu's per seat per nautical mile. The Jet A design requires 143 percent more energy, or 6102 Btu's/seat nmi. As previously stated in the basic guidelines, Table 14, both fuels are assumed to be available at the airport so the energy expended in manufacturing, refining, or trans- porting them to the airport is not involved in this comparison. In Figure 5, the effect of fuel cost on direct operating cost of the sub- ject aircraft is illustrated. Direct operating cost (DOC), expressed in cents per available seat per nautical mile, is plotted as a function of cost of both Jet A and ~ over a wide range of possible fuel prices shown along the abscissa in dollars per million Btu. For convenience, the price of Jet A is also presented across the top of the graph in the more familiar cents per gallon. To establish perspective, prices that U.S. international air carriers paid for Jet A in January, 19114 (214c1/gal.) and in September, 19114 (38c1/gal.) are indicated on the line representing the variation of DOC with Jet A fuel price. In addition, two estimates of prices for which LH2 might be made available at airports across the country are indicated on the line PAGENO="0253" z 247 Figure 5. Direct Operating Cost of SST Designs vs Fuel Price representing DOC for the LH2-fueled supersonic transport aircraft. The forecasts of LH2 prices, from [References 12 and 13], are based on pro- ducing hydrogen from lignite (at $2.50/ton) and from coal (at $LI.OO/ton), respectively. The price of LH2 from [Reference 12] ($2.50/lO6Btu) was based on use of a 2500 ton per day plant to produce gaseous hydrogen (GH2) and includes consideration of pipelining the hydrogen in gaseous form 1000 miles, and liquifying and storing at the airport site. The estimate from [Reference 13] (~3.o5/1o6 Btu)* was calculated for a 1000 ton/day OH2 plant and includes the cost of a 300 mile pipeline. A summary breakdown of the cost estimates from both references is presented in Table 6. The significant message from Figure 5, indicated by the horizontal dashed line, is that within the range of current prices for Jet A fuel, airline users could afford to pay $l.50/l06 Btu more for LH2 than for Jet A with- out suffering an increase in their direct operating cost. Due to the two lines on the chart representing DOC's being slightly divergent, as the cost of Jet A continues to increase an even greater differential can be allowed for the cost of LH2. Thus, for example, if Jet A costs $3.l5q~/ 106 Btu (38~/gal.) the allowable differential for equal DCC with LH2 fuel *[Reference 13] presents cost data adding to $2.8o/lo6 Btu through lique- faction. An additional cost of 25~/lO0 Btu was added [based on data from Reference 12] for storage. JET A FUEL PRICE - c/GAL 40 50 1.0 2.0 3.0 4.0 5.0 6.0 FUEL PRICE $/106 BTU l~ PAGENO="0254" 248 TABLE 6. ESTIMATES OF LIQUID HYDROGEN COST (Costs in $/i06 Btu) Item Source Reference 12 Reference 13 Fuel Basis Fue~~pst Hydrogen Gas Production Pipeline Transmission Distribution Hydrogen Liquefaction IH2 Storage Coal ($lijton) 0.17 0.73 0.15 (1000 miles) - 1.20 0.25 Lignite ($2.50/ton) 0J40 o.~6 0.30 (300 miles) 0.09 1.25 (0.25)* $2.50 $3.05 ~This cost was added by the present writer [based on data from Reference 121 to account for storage costs at the airport. is nearly $2,106 Btu. This puts the `permissible" cost of LH2 at about $5.lO/l00 Btu for Mach 2.7 supersonic transport operation, almost double the current projected costs. A comparison of some significant environmental acceptance parameters for the subject supersonic transport aircraft is shown in Table 7. Noise generated by the turbofan engines during takeoff is listed for the two standard measurements, sideline and flyover. Sideline noise was calcu- lated to determine the maximum Effective Perceived Noise Level (EPNL) in units of decibels (EPNdB) at a locus of points 0.35 nmi from the center- line of the runway, extending the length of the runway. Flyover noise is a similar calculation to determine the EPNL at a point 3.5 rimi from the point of brake release. Values of these parameters are listed for the subject aircraft using the two fuels. Although both designs meet the prescribed FAR Part 36 specification the LH2 aircraft is considerably quieter. The L112 airplane also offers appreciable reduction in overpressures caused by sonic boom. The table lists sonic boon overpressures calculated for three discrete points during the flight. The values for the hydrogen airplane are lower primarily because that aircraft is lighter and has much smaller wing area. In addition, during climbout and at start of cruise, it is considerably higher than the equivalent Jet A design. It is not likely however that with the overpressures shown, even an LH2-fueled SST would be permitted to fly supersonically over inhabited areas without significant additional reduction in sonic boom overpressure. Exhaust emissions representative of those from current Jet A-fueled turbo- jet engines during cruise flight are listed in Table 7 for comparison with emissions from LH2-fueled engines. Values of the first three items, oxides of nitrogen (NOX), carbon monoxide (Ca), and unburned hydrocarbons (UHC), are shown as reported from tests on a Jet A-fueled GE-J85 engine 18 PAGENO="0255" 249 TABLE 7. COMPARISON: ENVIRONMENTAL ACCEPTANCE PARAMETERS (Supersonic Transport Aircraft) LH2 Jet A Noise EPNdB Sideline 105.9 108.0 Flyover lO~4.3 108.0 Sonic Boom Overpressure, PSF . Start of Cruise 1.32 1.87 End of Cruise 1.19 1.1W Maximum Encountered 2.08 2.50 (During Clirnbout) Exhaust Emissions NOx g/kg Low 3~7* CO g/kg None 90* IJHC g/kg None 0.5* Odors None Objectionable H20 lb/n.mi 11t6 75.3 *Data for GE-J85, Simulated Flight at Mach 1.6, 55,000 ft. during simulated flight at Mach 1.6 at an altitude of 55,000 ft. Water vapor (H2o) emission data was calculated for both fuels as the total which would be produced during cruise flight by all four engines on the respec- tive aircraft. The emission of objectionable odors from the Jet A-fueled engines is noted for particular reference to operation on and near airports. The LH2-fueled aircraft will produce no CO or UHC because there is no carbon in the fuel. There should be no odor from the LH0-fueled engines. No firm data exists to serve as a basis for calculating ~he amount of NOX which might be produced from LH2 engines. Qualitatively, it can be stated that such emissions can be minimized by proper design of the combustion cycle. The fuel will be introduced into the combustion chamber in gaseous form. Gaseous hydrogen has the characteristic of very rapidly diffusing in air so that complete and uniform mixing will occur quickly. H2/air combustion has been demonstrated to proceed rapidly and smoothly over a wide range of mixture ratios, with very little evidence of the wide tem- perature variations found to exist in combustion chambers of Jet A-fueled turbine engines. Since NOx is formed by reaction of nitrogen and oxygen from the air at temperatures in excess of about 31400°F at dwell-times typical of conventional jet engines, the propensity of H2/air to mix and burn rapidly and smoothly, and the wide range of mixture ratios which can be used for temperature control, offers opportunity to engine designers to minimize NOx unmatched by any other fuel. Reviewing the results of this brief comparison of LIT2 and Jet A-fueled supersonic transport aircraft, it is apparent that use of LIT2 affords significant advantage in virtually all areas investigated. In the next section, subsonic aircraft will be similarly compared. 19 PAGENO="0256" 250 SUBSONIC TRANSPORT AIRCRAFT The investigation to evaluate the potential of using LH2 as fuel in subsonic transport aircraft involved both passenger and cargo-type designs. All passenger aircraft were designed for two ranges, 3000 and 5500 nini. The baseline requirement was to carry 1400 passengers at a cruise speed of Mach 0.85. Cruise speeds of Mach 0.80 and 0.90, and designs to carry 600 and 800 passen- gers were also investigated. Two aircraft configurations using LH2 fuel were designed and compared for the 1400 passenger payload missions. The cargo aircraft were designed for just two specific missions; one was to carry 125,000 lb of payload 3000 nmi, the other was to carry 250,000 lb 5500 nrni. Both were to cruise at Mach 0.85. Again, two aircraft configu- rations using LB2 fuel were designed and evaluated for both missions. The Lockheed-Georgia Company perforn~d the design and evaluation of the cargo aircraft. To provide a valid basis for reference in studying the advantages or dis- advantages of LH2-fueled subsonic transport aircraft, conventionally fueled Jet A aircraft designs were also established in accordance with the study guidelines to perform the baseline missions for both the passenger and the cargo aircraft. The reference passenger aircraft were designed to carry 1400 passengers at Mach 0.85. As in the study of the supersonic transport aircraft, particular care was taken to assure equivalency of both mission requirements and design technolo~r for the LH2 and the corresponding Jet A designs so valid comparisons could be made. Pictures of the two competitive designs of LH2-fueled subsonic passenger aircraft are shown in Figure 6. The one in the foreground was selected as the preferred design for comparison with the reference Jet A aircraft. The design in the background, which carries the LH2 in tanks mounted on pyloms above the wing, was originally proposed to provide an evaluation of potential advantages thought to exist for that configuration in safety, operations, and maintenance. It was recognized that there would he a performance penalty associated with carrying the large, externally-mounted tanks, but it was felt that the accessibility of the tanks for inspection and repair, plus their remote location from the passengers, might offer compensating advantages. Analysis did not confirm that these potential advantages were substantial enough to outweigh the superiority of the more conventional configuration in both performance and safety. Figure 7 is an illustration of the design of LH2-fueled cargo aircraft selected for comparison with the equivalent Jet A designs. As indicated in the picture, the nose of this airplane lifts to provide access to the cargo hold through the front. Hydrogen fuel tanks which contain the majority of the fuel required are located in the spine of the aircraft, over the cargo compartment. The tanks have a multi-lobe cross section to afford maximum practical utilization of the irregular shape of the space available. 20 PAGENO="0257" 251 Figure ~* - Fueled Subsonic Cargo Aircraft (Lockheed-Georgia Company) 21 Figure 6. Competitive Designs of LH2 Subsonic Passenger Aircraft 62-332 o - 76 - 17 PAGENO="0258" 252 The alternate design of LH2-fueled cargo airplane wem called a `swing tail" arrangement because the entire empennage and aft fuselage were hinged to permit access to the cargo hold through the aft end. This arrangenent basically contained the ~-~2 fuel in tanks located both fore and aft of the cargo compartment. In both aircraft designs the cargo space is wide enough to permit side-by-side loading of standard containers 8.5 ft wide by 9.5 ft high. For brevity, and to avoid repetition of material from essentially duplicate studies, the remainder of the discussion of subsonic aircraft will use passenger-type vehicles to describe the results and conclusions of the analysis. There were essentially no significant differences in the findings resulting from the comparison of efficient LH2-fueled aircraft designs with comparable Jet A-fueled aircraft which were functions of the type of pay- load carried. For those interested in the details of the parametric evalua- tion leading to final aircraft designs, and in specifics of the design or performance characteristics of either the passenger or cargo aircraft, [Reference 10] is recommended. Figure 8 illustrates the general arrangement of the preferred configuration of subsonic, LH2-fueled, passenger aircraft. Externally, there is little to distinguish the configuration from current conventionally fueled, wide body transports. Internally, the general layout of the passenger compart- ment, relative to the fuel tanks, is similar to that described previously for the supersonic transport aircraft. The passengers are located in the central portion of the fuselage in a double-deck arrangement with the fuel tanks located forward and aft. There is no provision for physical access between the passenger compartment and the flight station. However, in the subsonic design, which carries ~400 passengers, the fuselage is circular in cross section as shown. The passengers are seated in a 2_L~_2 arrangement on both decks for a total of 16 seats per row. Cargo is carried in space provided below the passenger compartment. Total payload weight for the ~~oO passenger design is 88,000 pounds. The aircraft illustrated in Fig- ure 8 is designed to carry that payload 5500 nmi at a cruise speed of Mach o.85. The 3000 nmi range, 1~00 passenger design is identical except that the fuel tanks are shorter because of the reduced fuel load required. The hydrogen fuel tanks in the passenger aircraft are the integral type, designed to serve as both fuselage structure and fuel storage vessel. Fuselage structural loads are transferred into and out of the integral fuel tanks through specially designed boron_reinforced, fiberglass tubes arranged in an interconnect truss framework. These tubes are designed to provide maximum stiffness, minimum weight, and minimum heat leak between the _1i23°F temperature of the tank and the ambient temperature of the aircraft struc- ture. Six inches of rigid, closed-cell, plastic foam applied to the outside of the aluminum tank provides insulation to limit hydrogen boil-off to an acceptable rate. The foam is, in turn, covered with a thin plastic sheet which serves as a secondary vapor barrier to prevent cryo-pumpiflg of air in the event the rigid plastic foam insulation develops minute cracks during aircraft service. A fiberglass or compbsite cover is wrapped around the entire assembly to provide mechanical protection for the vapor barrier and the plastic foam insulation. This outer cover also serves as the skin of the aircraft in the tank areas and provides aerodynamic cover over the truss framework joining the tanks to the conventional fuselage structure. 22 PAGENO="0259" Ui cJ~ DOUBLE DECK CABIN 16 PER SEAT ROW 173FT- FUSELAGEDIAj~ REAR LH2 TANKS Figure 8. General Arrangement: LH2 Subsonic Passenger Transport Aircraft PAGENO="0260" 254 Further protection is provided on the bottom of both fuel tanks, forward and aft of the cargo compartment beneath the passenger section. This pro- tection is 18 to 214 inches of energy-absorbing aluminum honeycomb supported from the tank bottom. It provides protection to the fuel tanks from for- eign object damage and from the effects of possible over-rotation or tail scrape during takeoff or landing. The wing ip~corporates high lift devices including 15 percent leading edge slats and 35 percent double-slotted Fowler flaps out to the outboard engine. Conventional ailerons are fitted to the outboard wing panel. Spoilers are used in flight for direct lift control and for deceleration during landing ground run. A comparison of several key design and performance parameters is presented in Table 8 for evaluation of the relative merits of the Jet A vs the LH2- fueled subsonic transport aircraft. The comparison is much the same as previously observed for the supersonic transport designs in Table 5; how- ever, in the present case, the differences are smaller because there is less fuel involved. The fundamental advantages gained from using hydrogen fuel in aircraft stem from substituting a high energy fuel for a lower energy fuel. In those airplane designs where the missiOn does not require much ftel it is apparent there will be less advantage to be gained by changing fuels. TABLE 8. COMPARISON: JET A VS LII SUBSONIC PASSENGER AIRCRAFT (1400 FAX, 5500 Ni~I. M 0.85) Factor LH2 Jet A (Jet A ~ LH2 Gross Weight Lb 391,700 523,200 1.314 Operating Empty Weight Lb 2)42,100 2)414,~4OO 1.01 Block Fuel Weight Lb 52,900 165,500 3.13 Thrust Per Engine Lb 28,700 32,700 1.1)4 Wing Area Ft2 3363 )4l86 l.2~4 Span ft 17)4 1914.1 1.12 Fuselage Length Ft 219 197 0.90 Height Ft 59.5 60.2 1.01 LID (Cruise) 16.1 17.9 1.11 SFC (Cruise) . Lb/Lb Hr 0.199 0.581 2.92 FAR T.O. Distance Ft 62)40 7990 1.28 FAR Landing Distance Ft 5810 5210 0.90 Aircraft Price $106 26.9 26.5 0.99 Energy Utilization Btu Seat n.mi. 1239 13814 1.12 214 PAGENO="0261" 255 Although the advantages of using 122 fuel in place of Jet A in the subject subsonic transport aircraft are not as dramatic as those observed in Table 5, they are nevertheless quite significant. In Table 8, th? conven- tionally fueled Jet A design is seen to be 3~4 percent heavier in gross weight, require over 3 times the weight of fuel, and to need engines that deliver l~4 percent more thrust than its counterpart designed to use hydro- gen fuel. There is negligible difference in operating empty weightand in purchase price of the two aircraft but the LH2 design has the capability of operating from shorter runways and it would be easier to handle on the ground in the terminal area because of its shorter wing span. The Jet A- fueled aircraft requires 12 percent more energy to fly its design mission. As in the case of the supersonic transport aircraft, the fundamental basis for the improved performance of the hydrogen-fueled design is the favorable tradeoff of its lift-to-drag ratio (L/D) and its specific fuel consumption (SF0) in cruise, relative to the equivalent Jet A-fueled design. Although the 122 design suffers from a degraded L/D, due to the low density and cryogenic nature of hydrogen, the much more favorable operating value of SF0 more than compensates. A graphical comparison of the relative sizes of the subject subsonic trans- port aircraft is shown in Figure 9. The significantly smaller wing area and shorter span of the LH2-fueled design are readily apparent, as is the shorter fuselage length of the Jet A airplane. Figure 10 is an illustration of the effect the price of each of the fuels has on direct operating cost (Doc) of the respective airplanes. The trends are the same as those observed in the discussion of Figure 5 for the super- sonic designs but, as noted earlier, the differences are less. In this case, for the Mach 0.85 cruise, 5500 nrni range, ~~oo passenger designs, user airlines could pay )4)~/lO6 Btu more for LH2 than for Jet A fuel and still break even on DOC. In the light of prices currently being paid for Jet A by U.S. international air carriers (38~/gal. in September l971~), as indi- cated on the figure, compared with prices forecast for LH2, considerable saving in DOC could be realized if LH2 aircraft were now in service. For example, at 3S~/gal. for Jet A, and assuming LIT2 could be purchased for $3.05/l06 Btu according to the estimate by Michel [Reference 13], use of LIT2 would affect a 6-1/2 percent reduction in DOC, a saving of tremendous consequence to airlines. Looking now at environmental a~pects of using hydrogen in subsonic trans- port aircraft, the next two tables. compare LH2 vs Jet A-fueled designs on the basis of noise and exhaust emissions, respectively. Table 9 lists noise levels in EPNdB calculated for both ranges. Three operational condi- tions are shown; flyover, sideline, and approach. The first two were defined previously, they are evidence of enginenoise only. The approach condition noise level is calculated for a location one nautical mile from the end of the runway (the threshold), and considers both engine noise and aerodynamic noise. *The'values shown in parentheses in the table are the limits calculated for the respective aircraft according to present FAR Part 36 regulations. The variation of, the limit values for the different aircraft reflects the fact the limits are specified as a function of aircraft gross weight. Since the LIT2 designs are lighter, they are required to be quieter. 25 PAGENO="0262" [~G SPAN rn 53 59.2 AREA rn2 313 389 FUSELAGE *OIA rn 6.63 5.84 LENGTH rn 66.7 60~j 256 Figure 9. Size Comparison: LH2 vs Jet A Subsonic Transport Aircraft JET A FUEL PRICE ~IGAL. FUEL PRICE S/10~ BTU Figure 10. Direct Operating Cost of Subsonic Aircraft Designs vs Fuel Price 0.85 400 PAX [10.190 krn (5500 n.rni.) JET A AiRPLANE SHOWN SHADED 0 0 40 50 z C.) 0 0 1.40 1.30 1.20 1.10 1.00 0.90 0.80 r I `I (M 0.85. 5500 N.M., 400 FAX) - - - P RICES -~ - SEPT'74* -- REFE REFER LH2 I PRICES 1 FORECAST ENCE 13~ FOR LH2 (TABLE 6) RENCE12t ~274 -± 2 4 26 PAGENO="0263" 257 TABLE 9. NOISE COMPARISON: LH2 VS JET A SUBSONIC PASSENGER AIRCRAFT Aircraft Noise Levels (EPNdB) Area of 90 EPNdB Contour (sq.mi.) Flyover Sideline Approach 3000 n.mi. LF12 Jet A 5500 n.mi. LIT2 Jet A L-lOll (Certification Tests) 88.1 (103.8) 92.7 (105.1) 89.2 (lO1~.9) 9~.2 (107) 96.0 (105.6) 86.1k (106.3) 86.1~ (106.9) 87.2 (106.8) 87.8 (107.6) 95.0 (lOT) 97.9 (106.3) 96.6 (106.9) ~ 98.I~ (106.8) 96.7 (107.6) 102.8 (107) 3.8 ~ ~.3 ~.7 6.6 = FAR 36 Limits All aircraft in the subsonic study were designed to be 20 dB quieter in sideline noise level than the FAR Part 36 specification. This was a condi- tion imposed on the engine designs, regardless of the fuel used. The dif- ferent noise level reductions calculated for the various aircraft for fly- over and approach thus reflect the effect of different thrust-to-weight ratios (T/W) and L/D of the aircraft. It may be noted in the table there is one situation where the LH2-fueled aircraft are slightly noiser than their Jet A-fueled counterparts; i.e., during approach. This results from a combination of characteristics. The LH2 aircraft have smaller engines because of their lower gross weights. They have lower lift/drag ratios, and their weight at landing is approximately equal to that of their Jet A counterparts. Because of the combination of equal weight, more drag, and smaller engines, the LH2 designs must operate their engines at a more ad- vanced throttle setting to maintain the required 30 glide angle during approach, thereby producing moro engine noise. The net result of noise produced during all three operating conditions is reflected in the final column of Table 9, which lists the area of the 90 EPNdB contour. This area is the sum of both the approach and takeoff conditions and indicates the number of square miles in the vicinity of the airport which would be subjected to noise levels greater than 90 EPNdB. The LH2 designs at both ranges show smaller areas thus affected. For reference, in Table 9, noise levels measured for the Lockheed L-lOll during FAA certification tests are listed. Since this wide-body transport is the quietest U.S. airliner in operation today, it is clear that signifi- cant improvement in transport aircraft of the future can be expected, par- ticularly if LIT2 is used as the fuel. 27 PAGENO="0264" 258 Goals for maximum emission of noxious products from the engines of the sub- sonic aircraft were specified by NASA for different operating conditions. As shown in Table 10, linus for carbon monoxide (co) and unburned hydro- carbon (UHC) were specified for engine idle. Limits on smoke and oxides of nitrogen (N0~) were stated for the takeoff power setting. The enissions of CO, UHC, and NOx are specified in grams per kilogram of fuel burned. Smoke emission is expressed in terms of the SPE 1179 smoke number standard. In addition to these emissions, it is of interest to note the difference in two other products of combustion which offer contrast between choices of fuels for commercial transport aircraft; water vapor (H20) and odors. Water vapor emission is specified in total pounds produced by the aircraft per nautical mile during cruise. No quantitative measure for odors is given, simply a statement that with Jet A fuel there is the familiar odor of kerosene which is objectionable to most people, whereas no odor results from the combustion of hydrogen and air. The level of emissions of CO, UHC, smoke, and NOx listed in Table 10 for combustion of Jet A fuel in advanced design turbofan engines were obtained from work reported by Pratt and Whitney Aircraft [Reference 114], General Electric Co. [Reference 15], and NASA-Lewis Research Center [References 16 and 17]. As previously noted herein, use of LH2 eliminates concern for CO, UHC, and smoke, and there is strong likelihood that NO emissions can be significantly reduced below that forecast for an engineXburniflg Jet A fuel, based on equivalent technology level. Note that the statement of NO~ emissions from the LH2 engine is stated in terms of grams per kilogram of fuel burned divided by 2.8 to reflect fuel flow rate for approximately TABLE 10. EMISSIONS COMPARISON: LH2 VS JET A AIRCRAFT Estimated Emission Level (g/kg Fuel) Emission Engine Product Condition Goal Jet A LH2 CO Idle 114 30 0 UHC Idle 2 14 0 Smoke Takeoff 25* 15* 0 "Ox Takeoff 13 12 H20 Cruise 141.9 Lb/n.mi.t 82.14 Lb/n.mi.t Odors Ground Objectionable None Operations _______ _______________ ___________________ *5AF 1179 Smoke Number tFor the 5500 n ~ range aircraft 28 PAGENO="0265" 259 equal thrust levels from both engines. The 2.8 factor is the ratio of heats of combustion of the two fuels, LH2 divided by Jet A. Water vapor from the hydrogen fueled airplane is shown to be nearly twice the quantity produced by the Jet A design. It is interesting to note that the quantity of water shown, which was calculated for the Mach 0.85 cruise, 5500 nmi range, ~400 passenger LH2 aircraft, would be a ribbon only 0.00008 inch thick if confined to four strips each equal in width to the diameter of the engine exhaust nozzles. Hardly a significant amount in comparison with the quantity of water vapor normally present in the atmosphere. CONCLUSIONS It has been shown that there is an urgent need to develop a fuel to replace petroleum-based Jet A for use in commercial transport aircraft of the future. In addition, results of studies to date have shown that hydrogen is an outstanding candidate. Technically, there is no question concerning its superiority. The use of LH2 as fuel for both subsonic and supersonic transport aircraft results in designs which are lighter, quieter, use smaller engines, are able to operate from shorter runways, minimize pollu- tion of the environment, and expend less energy in performing their mis- sions than equivalent designs fueled with Jet A. In addition, the hydrogen aircraft are physically smaller in span and wing area, but characteristi- cally have larger fuselages. At prices currently being paid by international air carriers for Jet A fuel, and using recent estimates of the price for which liquid hydrogen could be manufactured from lignite or coal, pipelined to the airport site, and there liquefied and stored, LH2-fueled aircraft could be operated by the airlines at significant saving in direct operating cost. Analysis of operations and maintenance requirements and procedures for LH2- fueled aircraft in airline type operations, reported in [Reference l0J, con- cluded that there need be no significant difference in turn-around schedules compared with conventional practice with Jet A-fueled aircraft. The equip- ment required to perform operations like refueling will obviously be differ- ent from that used with Jet A; however, if it is properly designed, neither the number of personnel involved nor the elapsed time required should be adversely affected. Finally, considering the comparative safety of LH2 and Jet A fuels in air- craft, a brief analysis resulted in the tentative conclusion that the hazards associated with the use of LH can be less than those with Jet A. For example, in an otherwise survivab~e crash in which equal energy quan- tities of Jet A and hydrogen fuel are burned, the hydrogen fire would re- sult in significantly less damage to the surroundings immediately beyond the fire area because of two factors; 1) the relatively short duration of hydrogen fires, and 2) the very low emissivity of the products of combus- tion. Hence, passengers not directly in the path of the flames would have a higher probability of survival and a lower injury rate. Testing to more realistically assess this situation was recommended in Reference 10. 29 PAGENO="0266" 260 A],though there is little doubt it is technically feasible and desirable to develop LH0-fueled transport aircraft for initiation into commercial ser- vice in l9~O, there are other facets of the total problem which must also be faced in order to successfully accomplish the conversion of commercial aviation to the new fuel. These items are the following: * There must be an international commitment for hydrogen, and com- mercial aviation must be mandated to use it. * Processes to manu~acture the required quantities of hydrogen economically must be developed and associated plant and equipment built. * Facilities must be provided at selected airports to liquify and store LH2, and to deliver it to aircraft in a safe and efficient manner. * I~esearch and technolo~j development for aircraft and engine require- ments must be authorized and successfully accomplished in a timely manner. Successful resolution of these issues involving domestic and international cooperation in planning and finance, in addition to resolution of tech- nical problems of process development and plant design, constitute the real problems confronting aviation usage of liquid hydrogen fuel. 30 PAGENO="0267" 261 REFERENCES 1. Hubbert, M. King, "The Energy Resources of the Earth~" Scientii~c American, September 1971, p 11~9. 2. Unpublished manuscript from Wu, Yau, Visiting Associate Professor of Mechanical Engineering at M.I.T. Presented in "Urban Transportation: Perspective on Mobility and Choice," NASA/ASEE l97~4, NASA Contract NGT 1~7_OO3_O28, NASA-Langley Research Center and Old Dominion Univer- sity, Fig. 2-12, p 71. 3. "Aircraft Operating Cost and Performance Report for Calendar Years 1972 and 1973," Civil Aeronautics Board, Bureau of Accounts and Statistics. 4~ Personal communication to Mr. EdwardF. Versaw, Lockheed-California Company, from EXXON Corporation, U.S.A., January l~, 1975. 5. Jaarsma, F., "Impact of Future Fuels on Military Aero-Engines," National Aerospace Laboratory (NLR) Amsterdam, The Netherlands, pre- sented at l971~ AGARD Annual Meeting, Paris, France, 26 September l97~4. 6. Brewer, G. Daniel,"The Case for Hydrogen-Fueled Transport Aircraft," Lockheed-California Company, May l97~ Astronautics and Aeronautics, p I~O. 7. "Hydrogen and Other Synthetic Fuels," Synthetic Fuels Panel, prepared for the Federal Council on Science and Technology R&D Goals Study under the cognizance of the U.S. Atomic Energy Commission, September 1972. 8. Whitlow, John B. Jr., Eisenberg, Joseph D., Shovlin, Michael D., "Potential of Liquid Methane Fuel for Mach 3 Commercial Supersonic Transports," NASA TND - 31~7l, 1966. 9. Brewer, G.D.; "Advanced Supersonic Technology Concept Study - Hydrogen Fueled Configuration," NASA CRllt~, 718, prepared by the Lockheed California Company under Contract No. NAS 2-7732, January l97~. 10. Brewer, G.D.; Morris, R.E.; Lange, R.H.; and Moore, J.W.; "Study of the Application of Hydrogen Fuel to Long-Range Subsonic Transport Air- craft," NASA CR 132559, prepared by Lockheed-California Company and Lockheed-Georgia Company under Contract HAS 1-12972, January 1975. 11. Contract NAS 1-12288, "Study of Structural Design Concepts for an Arrow-Wing Supersonic Transport Configuration," NASA-Langley Research Center to Lockheed-California Company, May 21, 1973. 12. Johnson, J.E.; "The Economics of Liquid Hydrogen Supply for Air Transportation," Advances in Cryogenic Engineering, p 12, Vol. 19, Edited by K.D. Timmerhaus, Plenum Press, New York, l97~4. 13. Michel, J.W.; "Hydrogen and Exotic Fuels," Oak Ridge National Labora- tory, ORNL-TM-~46l, June 1973. 31 PAGENO="0268" 262 REFER~CES (Continued) i1~. Brines, G.L., "Studies for Determining the Optimum Propulsion System Characteristics for use in a Long Range Transport Aircraft," NASA CR-120950, 1972. 15. ANON., "Propulsion System Studies for an Advanced High Subsonic Long Range Jet Commercial Transport Aircraft," NASA CR-121O16, 1972. 16. Grobman, Jack; Norgren, Carl; and Anderson, David, Turbojet Emissions, Hydrogen Versus JP. NASA TM-X-68258, 1973. 17. Grobman, Jack, and Ingebo, Robert D.; Jet Engine Exhaust Emissions for Future High Altitude Commercial Aircraft. NASA TN-X-7l5O9, 197I~. 32 PAGENO="0269" 263 John A. Casazza Vice President, Planning and Research Public Service Electric and Gas Co. Newark, N.J. WHAT CAN HYDROGEN DO FOR AN ENERGY COMPANY? Introthic tlon In order to continue to meet the needs of this world we must use our resources wisely. These resources can be classified into three broad categories: natural, human, and capital. The natural resources consist of air, water, land and include such fuels as coal, oil, gas, and uranium. Our human resources, our scientists, engineers, and our skilled and unskilled labor are limited and must be used wisely. Our capital resources provide the tools through which our human resources can use our natural resources for the benefit of all the people of this earth. To conserve our limited capital we will have to make the best possible use of our existing energy systems. In using these resources we need to recognize that energy is closely tied to all mankind's need including food and water supply. A total system optimi- zation is needed. We cannot optimize the use of one.resource to the detriment of the total system. In this process, it is essential that new technology be vigorously pursued and brought into use. Moving Targets and the Age of Uncertainty The role of hydrogen and hydrogen-related technology in utility systems will depend on future growth, cost trends, new technology, and environmental requirements. Each of these areas presents rapidly moving targets for hydrogen as well as other energy forms. Examples of the speed of change are the rapid excalation in fossil fuel prices and the shortage of capital which has PAGENO="0270" 264 resulted in more than 60, 000 MW of new electric generating capacity being delayed or cancelled in the U. S. A. since the first of the year. To be able to meet such uncertainties in the future we must maintain as many options and as much flexibility as possible in developing our energy systems. Why Hydr~g~~ We in PSE&G believe that hydrogen can play an important role in providing additional options and flexibility in meeting our future national needs from energy to food to transportation. Hydrogen can make possible the use of our nuclear energy resources for many purposes. With the intriguing future possibilities for the use of hydrogen, the funda- mental question becomes: When and how should we pursue the development and use of hydrogen technology in our energy system? Hydrogen can be produced from liquid and gaseous fossil fuels through catalytic oxidation and steam reforming, and from coal through partial oxidation and steam reforming. SNG plants and coal gasification plants have the potential, with some modification, of producing hydrogen. It can also be produced from water, at the present time, through electro- .lysis. Considerable research is underway on the thermochemical splitting of water to obtain hydrogen including the efforts at Euratom in Italy, the efforts of General Atomics in California, and the work at IGT. The production of hydrogen by this mechanism is not likely to occur before 1990. The Texas Gas Transmission Corporation is presently sponsoring work at the KMS Fusion Laboratories on the use of high-speed neutrons produced by laser fusion to split water molecules into hydrogen and oxygen. KMS predicts that it may be possible to produce hydrogen by such a process in the late l970s. Another possibility for the production of hydrogen is to use the neutrons that will be produced by a device similar to the two-component Torus device (TCT) presently under consideration for installatiai at the Princeton Plasma Physics Laboratory in 1979. The TCT project is expected to be funded by the U. S. Government at approximately $200, 000, 000. We in PSE&G felt several years ago that hydrogen research was justified if we were to develop the necessary technical expertise and the needed personnel to be able to cope with the problems of hydrogen in the future. Accordingly, we embarked on the following program: PSE&G Hydrogen Activities The approach selected for PSE&G in the area of hydrogen systems consists of both analytical studies and equipment and systems development. Analytical studies using parametric analysis to determine breakeven costs and key variables include: PAGENO="0271" 265 1. Long-range system economic evaluations of hydrogen production from off-peak nuclear energy and dedicated nuclear plants. 2. Comparison of costs of hydrogen storage systems with alternate forms of storing energy. (Included in this work is a study of all potential forms of energy storage funded by a grant from the AEC.) 3. Integration of our electric and gas systems using hydrogen to take advantage of the seasonal diversity between these systems. 4. Studies of the future uses for hydrogen in making steel, for transportation, as a fuel, and in the production of fertilizer. 5. Studies of the installation of fuel cells in individual customer premises versus installation of fuel cells in substations. The equipment and systems development projects include: 1. Support of the fuel cell development program including the Pratt & Whitney 26 MW FCG- 1 development and the gas industry Target Program. The total PSE&G investment in fuel cell research will be $6, 800, 000 by the end of 1976. A three-phase fuel cell installation at the PSE&G City Dock Substation was the first use of fuel cells on a working electric utility system. 2. Developing improved hydrogen storage methods, specifically the metal hydride storage concept working with the Brookhaven National Laboratory and the AEC. 3. Use of an electrolyzer-hydrogen storage fuel cell system in an actual power supply situation to obtain operating experience and costs, the vitally necessary training of people in the handling of hydrogen, and the data for `scaling up" to larger installations. A brief description of some of the results of this work may be of interest. Hydrogen Production Prom Off-Peak Nuclear Energy One solution to the dwindling fossil fuel supply problem is the substitution of nuclear energy for fossil fuel energy. Because of variations in the patterns of usage of electric energy and the proportion of our electric requirements that will be provided from nuclear plants, we should have nuclear generation capacity available at certain off-peak times for use to produce hydrogen by electrolysis. Our studies have shown that this is a more economic approach and provides better utilization of capital than the installation of dedicated PAGENO="0272" 266 nuclear plants for the sole purpose of electrolytic production of hydrogen. Further optimization of sca~rce captial resources may also be achieved through the use of the existing gas system to distribute hydrogen, possibly blended with natural gas. A key question is-how much nuclear off-peak energy will be available and when? Availability of Off-Peak Nuclear Energy A study of the availability of off-peak nuclear energy on the PSE&G system and the key factors determining it was made about a year ago. This analysis considered not only the daily and seasonal load cycles that are forecast, but also the limitation in minimum acceptable boiler loadings and the need to dispatch generation so as to provide adequate geographical area coverage. Figure 1 shows that once the nuclear capacity on an electric power system exceeds 30% of the total system capacity, rapidly increasing amounts of off- peak nuclear energy should become available with further nuclear generation additions. Since long-range plans for many systems call for about 50% of the generating capacity to be nuclear, extrapolation of this curve indicates that close to 10% of the total energy generated could be available in the form of off-peak nuclear energy. OFF-PEAK NUCLEAR ENERGY AVA~LABIL1TY £3 AVAtLABLE 0FF-PEAK : NUCLEAR ENERGY (% OF TOTAL SYSTEM 3 ENERGY PRODUCED) ~O~2O 25 30 ~ 45 SYSTEM NUCLEAR CAPACITY (% OF TOTAL SYSTEM CAPACITY) FIGURE 1 Another way of illustrating this trend is shown in Figure 2. The ratio of average incremental peak energy cost to average incremental off-peak energy cost is shown to rise from 1. 5 in the rnid-70s, to 7 by the year 2000, if no energy storage is provided. This tendency for the ratio between on-peak cost and off-peak cost to increase leads to greater desirability of using off-peak energy to provide some of the on-peak energy needs. The possibility of associated fossil fuel savings justifies increased attention to.all forms of energy storage, not only hydrogen. PAGENO="0273" 267 RATIO OF AVERAGE INCREMENTAL PEAK TO OFF-PEAK ENERGY COSTS ENERGY COST RATIO AVERAGE INCREMENTAL ( PEAK COST %\ AVERAGE INCREMENTAL OFF-PEAK COST 1970 1975 1980 1985 1990 1995 2000 YEAR FIGURE 2. "Electrolyzer" and "Reformer" Fuel Cells Low-cost, off-peak power from nuclear plants could be used to electrolytically produce hydrogen which could be stored for later delivery to fuel cells during peak electric load periods. This concept of the "electrolyzer" fuel cell plant in which highly efficient electrolyzers would produce hydrogen needed by fuel cells was compared on a total cost basis with the "reformer" fuel cell where the fuel conditioning section or reformer converts hydrocarbon fuels to hydrogen gas which is then fed to the fuel cell power section. Figure 3 shows the breakeven capital cost differential for the "electrolyzer" fuel cell over the "reformer" fuel cell based on operating cost savings. In this analysis, the breakeven differentials in capital costs will just offset the operating savings or penalties. The curves show that based on off-peak energy costs in the order of 8 mills per kWh and fossil fuel costs approaching $1. 50 per million Btu, the "electrO- lyzer" ~uet cell plant will have to cost in the order of $ 100 less per kilowatt than the "reformer" fuel cell plant to be economic based only on operating savings. For off-peak energy costs of 3 mills per kWhr (nuclear) and fossil fuel costs of about $2. 00 per million Btu, the "electrolyzer" fuel cell plant can be economically justified even if it costs $ 125/kW more than "reformer' fuel cells. 8 7 6 5 4 3 2 62-332 0 - 76 - 18 PAGENO="0274" 268 BREAK-EVEN CAPITAL COST DIFFERENTiAL FOR "ELECTROLYZER" FUEL CELL OVER THE "REFORMER" FUEL CELL 350 300 FOSSIL-FIJEL COSTS, 250 ~ 6/10' Blu 200 Ni OPERATING HOURS' 2000 EFFICIENCIES: BREAK-EVEN CAPITAL 150 \, ~ PRESENT TECHNOLOGY COST, 91kW 100 N `~`-,~ r'ELEcTRoLYzER' N ~\ 405J FUEL CELL 50 "s~ 1 `REFORMER' I I I. FUELCELL 0 123 56 8910 AVERAGE INCREMENTAL OFF-PEAK ENERGY COST, MILLS/kWhr FIGURE 3 The "Electric/Gas Two-Way Energy Transformer" The PSE&G system is located in a mixed urban and suburban area. The pro- jected peak electric loads will be about 8, 500 MW in 1980, increasing to about 20, 000 MW in the year 2000. The generation system consists mostly of fossil- fuel steam and combustion turbine units. The major portion of additional capacity is being provided through the addition of large nuclear units. An extensive natural gas distribution system exists in the area which delivers approximately twice as many Btu's as the electric system. Our electric system has a pronounced summer peak while our gas system has a predominant winter peak. While changes of utilization practices in the future, possibly influenced by rate policies, could change this situation, loss of load diversity ič not considered likely. Because of the potential savings from coupling electric and gas networks, we have made some preliminary studies of how two such systems could be integrated. Because of severe limitations in the supply of natural gas, our study was based on returning to the gas system at peak times all the energy removed from it at off-peak times. The extent of the diversity is limited by the cap- ability of the electric system to return energy to the gas system during the electric system's off-peak period. With this limitation, the maximum inter- change between the two systems is about 10% of the net annual energy generated by the electric system (or about 5% of the net annual gas system send-out). Figure 4 illustrates the basic study approach. First, the electric system was assumed to be expanded independently with new generation capacity additions of 50% gas turbines and 50% nuclear generation. Similarly, the PAGENO="0275" 269 gas system was expanded independently by adding gas sources and gas storage. ASSUMED ADDITIONS TO EXISTING ELECTRICAL AND GAS SYSTEMS FOR INDEPENDENT EXPANSION GAS TURBINES ELECTRIC SYSTEM __________ NUCLEAR 1 1 ELECTRIC (50%) LOAD GAS SYSTEM GAS I GAS SOURCES I LOAD I GAS STORAGE ASSUMED ADDITIONS TO EXISTING ELECTRICAL AND GAS SYSTEMS FOR COORDINATED EXPANSION GAS TURBINES ___________ (REDUCED) __________ NUCLEAR ________________________ ELECTRIC (50%) LOAD I TWO-WAY I ELECTRIC/GAS I ENERGY __________ ~RANSFORMER _________ GAS I ___________ GAS SOURCES_[ __________ 1 LOAD GAS STORAGE (REDUCED) FIGURE 4 The integrated electric-gas-hydrogen system was formed by the link or connection between the gas and electric networks provided by a "two-way electric/gas energy transformer Figure 5 shows a conceptual idea of bow such an energy transformer might function. The use of the electrolysis unit rectifier to also function as an inverter for the fuel cell, the condensation of water in the fuel cell exhaust to provide the water needed for electrolysis, and combining common components in the reforming and methanating equip- ment, all offer interesting possibilities for minimizing costs. Depending on various parameters, the break-even capital costs range from a low of about $ 1507kw to a high of about $ 600/kw of output from the fuel cell. PAGENO="0276" 270 CONCEPTUAL "TWO-WAY ELECTRIC/GAS ENERGY TRANSFORMER" 0, ~ ELECTRIC (FOR SALE) NATURAL SOURCE ~ SOURCE D.C. Ji~čTROLYSISL_. ri UNIT ~ CO' I EXHAUST H,O ~H, H CII RECTIFiER IHYDROGEN h--[REFORMER INVERTER STORA~j..~4_METHANATOR ~ L_~Ib. H, CH~ tAIR FIGURE 5 Hydride Storage With the need for energy storage at dispersed urban locations in energy systems of the future, we became involved in research and development in the use of metals hydrides for hydrogen storage. Metal hydride storage can be viewed as a desirable compromise between the low temperatures of hydrogen cryogenic *storage and the high pressures of compressed gas storage. At the PSE&G Energy Laboratory we have in operation the first complete test facility for demonstrating the hydrogen energy storage concept on a utility system. In our facility, hydrogen is produced by a commercially available electrolyzer and stored in a hydride reservoir. The stored hydrogen is then released as fuel for a specially modified Pratt & Whitney 12. 5 kW fuel cell which supplies a portion of the electrical requirements of our laboratory building. This fuel cell was developed in the Target Program. The metal hydride storage unit is the result of AEC sponsored research at Brookhaven National Laboratory, where the Department of Applied Science built the unit to performance specifications supplied by PSE&G. The reservoir con- tains iron-titanium particles, a silvery sand, which costs about $z/lb. The hydride is a chemical compound of hydrogen and iron-titanium. Iron-titanium is attractive because hydrogen as a gas can be combined or removed from the metal at moderate working pressures (500 psi) and within a few degress of ambient temperature. Hydrogen can be stored at densitites comparable to those used in liquid storage without the associated energy expenditures of 5 kWhr/pound for liquefaction. - PAGENO="0277" 271 Preliminary tests of the unit at the Energy Laboratory have proven success- ful.~ Further testing will determine more precisely the relationship between hydrogen charging and discharging and the temperature and rate of flow of the circulating water which is used as a heat transfer medium. Another important question is whether repeated charging and discharging cycles will cause de- gradation of the iron-titanium particles. This hydrogen test facility is providing valuable working expertise with hydrogen production, storage, and utilization. Hydrogen Versatility The versatility of hydrogen is especially attractive to combination utilities, like PSE&G, that provide both gas and electric service. It also provides a potential mechanism for electric and gas companies to coordinate for their mutual benefit. For example, studies indicate that up to 8 percent hydrogen could be added to the gas system to supplement our gas supplies without change in the gas distribution system. The potential use of hydrogen for transportation and the need for hydrogen to produce fertilizer offer intriguing additional possibilities. How to "Get There" We believe the best way to get started is in an area that has the potential for a short-term payoff such as PSE&G efforts with fuel cells and the hydride storage unit. If short-term efforts are successful, further development and progress will undoubtedly evolve. Future steps needed are: I. Extensive research and development to improve efficiencies and to decrease capital costs of hydrogen production, storage, and distribution facilities. 2. The continuing growth of the nuclear industry for producing hydrogen either electro- or thermo-chemically. (The recent postponment of nuclear commitments throughout the country will delay the availability of off-peak nuclear energy for the production of hydrogen.) 3. A significant effort by the gas industry to determine the ability, of existing gas transmission and distribution systems to transmit hydrogen both alone and blended with natural gas. . 4. Increased government and industry funding of hydrogen R&D activities. 5. Social acceptance of a new energy system through public information and education. Safety aspects should be frankly discus sed. PAGENO="0278" 272 Energy conversion systems not dependent on fossil fuels will be the energy conversion systems of the future. Certainly, in the next 20 years, the need for synthetic or so-called secondary fuels will increase. Our diminishing fossil fuel reserves and increasing costs coupled with environmental require- ments should provide the incentives for the broad expenditures for research and development work needed to develop uses for hydrogen. In the long-term future, which could range anywhere from 20 to 100 years, as fossil feedstocks become scarce, nuclear energy will probably be used to produce hydrogen from water on a bulk scale either by nuclear or thermochemical means. Nuclear and solar devices will become the primary sources of energy while electricity and hydrogen will co-exist as the most important secondary energy forms. Conclusions While the role of hydrogen in the future is not yet clear, a number of conclusions can be drawn at this time: 1. We cannot afford to abandon our existing energy systems. 2. Hydrogen has the potential to complement both our electric and gas systems as well as helping in the solution of the world's transportation and food problems. 3. Hydrogen's future role will result in the need for more nuclear power, and possibly more electricity, than indicated bycurrent projections. In the past, .we have reacted to change. In the future, we need to cause change. We need to prevent fires -not put them out. We need to move for- ward vigorously in determing hydrogen's future role. PAGENO="0279" 273 STANFORD RESEARCH INSTITUTE ~ Menlo Park, California 94025' U.S.A. Final July 1975 THE HYDROGEN ECONOMY A Preliminary Technology Assessment By: EDWARD M. DICKSON JOHN W. RYAN MARILYN H. SMULYAN Prepared for: RESEARCH APPLIED TO NATIONAL NEEDS NATIONAL SCIENCE FOUNDATION WASHINGTON, D.C. 20550 Grant ERP73-02706 . SRI Project EGU-2836 PAGENO="0280" 274 SECTION I SU?~IARY A1~D RECO~\1ENDATIONS The hydrogen economy concept is broad both in scope and in societal consequences. However, because large changes are involved, the concept could be implemented only slowly even once it was deemed desirable. Accordingly, society has ample time to develop more information and to weigh the advantages and disadvantages of the hydrogen economy concept. The luxury of this long lead time should not be squandered, however, for some of the fundamental course-setting decisions must be made soon. This section briefly summarizes the major conclusions of the report and presents some general public policy implications. In addition, a prioritized list is given for research and development activities needed to ensure that the knowledge necessary to evaluate future policy deci- sions becomes available. 1 PAGENO="0281" 275 SECTION I--SUMMARY AND RECOMMENDATIONS A. Use of Hydrogen Hydrogen is not a primary energy resource. Instead, it must be regarded as an energy form, or an energy carrier, for like electricity, some other primary energy resource is needed to produce it. Hydrogen can be produced from water and hydrocarbon fuels by thermochemical or electro- chemical processes. Today, the demand for hydrogen is low and hydrocarbons are its major source. However it is the thrust of the hydrogen economy concept that, in the future when hydrocarbons are not so readily Ivailable, hydrogen would be obtained from water by various means and would replace petroleum products. Again, like electricity, hydrogen could be derived from any primary energy resource, including nuclear, solar, or geothermal. Today, much of the world energy requirement is derived from petroleum or natural gas, two fuels that are highly favored because they are easily transported in, liquid or gaseous form. For mobile applications, petroleum products are used almost exclusively because their high energy content per unit weight and volume and their ease of containment greatly facilitate automotive and air travel. Hydrogen, in either gaseous or liquid form, could replace petroleum products or natural gas in essentially every application in which the latter are now used. However, liquid hydrogen is incompatible with existing liquid fuel distribution systems, and there remain some upresolved questions concerning the use of the existing natural gas delivery system for hydrogen. While some envision an energy economy in the distant future that is essentially all-electric (aviation being the most important exception), others envision a hydrogen/electric future in which hydrogen would serve 2 PAGENO="0282" 276 as a common denominator fuel for all mobile and stationary applications in which it proved superior to electricity. Moreover, there would be a cross-link between hydrogen and electricity by virtue of the electro- chemical decomposition (electrolysis) of water to make hydrogen and the electrochemical oxidation of hydrogen (in a fuel cell) to make electricity and water. This examination of the hydrogen economy concept has produced the following conclusions: * The hydrogen/electric concept of the future energy economy is meaningful to the extent that hydrogen could, indeed, replace petroleum or natural gas in essentially every application. * The use of hydrogen, however, would rarely prove the most economical alternative either in monetary or basic energy resource terms for the rest of this century. * In certain end uses--especially aviation--hydrogen may be the superior alternative energy form for the long term. * Hydrogen would offer many significant environmental benefits at the point of use, but, like electricity, there would still be environmental damage at the point of production. * The transition from the present fossil-fuel energy economy to a hydrogen economy would be long--probably a century. * Because of the long lead times required, even a vigorous program to promote the use of hydrogen derived from coal or from nuclear power and water could not make a significant contribution to U.S. energy independence before the year 2000. * However, a transition to a hydrogen economy could be considered permanent. Consequently, the concept deserves consideration commensurate with that given to more temporary energy economy solutions such as synthetic methane or crude oil derived from coal and oil shale. B. Transition to Hydrogen Decisions in both the private and public sector are generally made with a planning horizon of 5 to 10 years. In the private sector, especially, 3 PAGENO="0283" 277 this time horizon derives from the realization that money has a value that varies with time (even in the absence of inflation). Corporations formally discount the value of future earnings anticipated from an investment according to the profit or interest the same investment could earn else- where. As a result, a dollar that could be earned this year is considered more valuable than a dollar that could be earned next year. Discounting of the future tends to justify a preoccupation with short- rather than long- term goals in decision making. During periods when capital formation falls far short of the quantity desired for new investment, monetary interest rates increase. This in turn steepens the rate at which the long-term future is discounted. In such times, the short term becomes the paramount concern. Because massive investments are required and technologies with long lead times would have to be deployed, a transition to hydrogen on a large scale would take many decades (probably a century) before it was reasonably complete. As a result, corporations (and governments as well) tend to dismiss hydrogen in favor of concentrating those activities that continue the viability of the existing order. Thus, for example, instead of hydrogen, the natural gas industry is concentrating on making synthetic methane from coal and the petroleum industry is concentrating on making synthetic crude oil from oil shale and coal. This concentration derives from the fact that those materials can be blended with traditional supplies without much pertur- bation of either the distribution of end-use aspects of the energy system. Although coal gasification and liquefaction and oil shale development require large amounts of capital investment, they offer the advantage of being carried out on an incremental basis without the fundamental alteration of the entire fuel supply system. Because the transition to hydrogen is genuinely only a long-term option, and would take more time to implement than the private sector is normally concerned about, the role of hydrogen in the future U.S. energy 4 PAGENO="0284" 278 economy is a rightfully matter of public policy. The potential effects of the range of governmental attitudes towards hydrogen--neutral, pro, and anti--are considered below: * Neutral Government Policy If the federal government remains neutral towards the future of the hydrogen economy, largely through a failure to take a position one way or the other, then the decision about what energy form will ultimately occupy the niche now filled by hydrocarbon fuels will be left to the market mechanism and institutional compatibility as influenced by the results of piecemeal private sector and federal R&D. In particular: - Hydrogen would not be likely to gain favor until fuel options more compatible with existing corporate, societal, and governmental institutions have been exploited and, perhaps, nearly exhausted. This would make the transition period needlessly rushed and, hence, disruptive. - Hydrogen could not contribute much to the U.S. energy mix before the year 2000, and even then only a few sectors would be affected. - The changeover period would be so long that neither would societal consequences be felt acutely, nor would environmental benefits be realized quickly. - Institutional reluctance to embark on change is likely to impede private sector R&D spending for a hydrogen economy; as a result, federal R&D spending is needed if only to ensure that an adequate knowledge base develops to preserve the option of a large-scale transition to hydrogen. - The transition would be paced by necessary improvements in the technology of hydrogen production and the consequences of these on the cost of hydrogen production compared with that of alternative fuels. - The first applications would be those in which hydrogen was produced and used captively without involving its sale in the energy marketplace. - Applications that depend on the deployment of a new fuel network that would have to compete with an existing and widespread fuel distribution network-- such as gasoline for private automobiles and methane gas to residences--would be the last to be imple- mented. 5 PAGENO="0285" 279 * Pro-Hydrogen Governmental Policy If the federal government were to adopt a pro-hydrogen economy policy, the total duration of the changeover period might be reduced, but the initial changes could not be speeded up appreciably because of the long lead times involved. The following applications are probably the most readily and quickly affected by a pro-hydrogen policy: - Lohg-distance domestic commercial avaiation (this sector probably could be converted to hydrogen by the year 2000 largely because there already is a high degree of government regulation and participation). - Electric utility load-leveling facilities using hydrogen generation and storage. - Nuclear steelmaking with hydrogen used for iron ore reduction. These sectors are the most susceptible because they either involve only hydrogen produced and used captively or a distribution network with only a few key dispensing locations. * Anti-Hydrogen Government Policy If the federal government were to adopt an anti-hydrogen energy economy policy, largely manifested by failure to support significant hydrogen R&D efforts while giving support to R&D on other synthetic fuels, the emergence of the hydrogen economy in the United States would probably be delayed until fossil-fuel. reserves of all kinds become truly scarce globally. Countries with fewer domestic energy resources than the United States, however, would probably take the R&D lead and begin actual implementation of some aspects of the hydrogen economy concept before 2000. The United States could then find itself a buyer of foreign hydrogen economy technology. Even without U.S. governmental R&D support, however, the following components of a hydrogen economy concept would probably begin to be deployed in the United States within 30 years: - Electric utility load-leveling using hydrogen generation and storage - Nuclear steelmaking with hydrogen used for chemical reduction of iron ore. The emergency of a hydrogen economy would, of course, be related to other future events. Some of the key events that would play critical roles and therefore should be regarded as signposts are the following: 6 PAGENO="0286" 280 * Federal government policy concerning U.S. energy independence. If dependence on foreign sources of oil becomes intolerable and the federal government makes a sustained effort to develop domestic energy resources on a massive scale, the production of hydrogen for mobile applications would probably be stimulated late in the century. * Clarification and stabilization of the environmental and occupational health policies of coal mining. In the short term (assuming no additional constraints on nuclear power), coal would be the most economical large-scale primary energy resource for the production of hydrogen. * Resolution of the controversies about price regulation of natural gas and imports of liquid natural gas (LNG). Natural gas is one of the key fuels with which hydrogen would have to compete as transition began. If natural gas is deregulated, it is commonly expected that demand will fall while supplies and reserves will rise (owing to increased incentives for exploration). This would both diminish the size of the gaseous fuel market that hydrogen could ultimately serve and postpone gas industry interest in hydrogen. Importation of LNG could greatly extend the viable lifetime of the natural gas industry in its present form. * Resolution or quieting of the controversies and constraints of power from nuclear fission (fuel availability after about 1985, long-tern disposal of nuclear wastes, and power plant siting). In the long term, nuclear power would be one of the major primary energy sources for hydrogen production. Although coal would be a primary source in the beginning, should the role of nuclear power be diminished, then the emergence of a hydrogen economy would probably have to await economically viable solar energy technologies. In particular, if nuclear power does not develop as planned, electric power generation would have to become even more dependent on coal than is presently envisioned, and this would tend to limit the coal available for hydrogen production, thereby impeding the earliest steps towards hydrogen. In addition to the factors listed above, there are numerous related technological developments that would tend either to enhance or diminish the prospects of a transition to hydrogen. These are summarized below: Enhance * Economical solar energy collection. Many solar energy technologies require means to store energy before the energy becomes very useful; storage of solar energy as 7 PAGENO="0287" 281 hydrogen would stimulate delivery of energy in hydrogen form. * Advances in chemical catalysis using abundant and low- cost materials. This would lower the cost and remove the constraint of catalyst availability on electrolyzers and fuel cells. * Development of practical superconductors with transition temperatures around 26~K. This would allow use of liquid hydrogen as a refrigerant and would stimulate advancement of liquid hydrogen technology. Diminish * Technical and economic success of nuclear fusion to produce electricity. This would tend to advance the evolution of an all-electric type economy, thereby diminishing the role of hydrogen. * Development of long-lived, low-cost, high energy- and power- density electric storage batteries suitable for electric utilities and electric cars. This would diminish the long- term need for hydrogen in mobile applications. In addition, nighttime battery charging would help level electric utility loads, thereby undercutting a major potential captive use of hydrogen. Such use would otherwise be expected to advance the hydrogen technology state-of-the-art. In general, evolution of a hydrogen energy economy would be more likely to occur in an era of long-term economic prosperity, stable energy and environmental policy, and international peace than in an era marked by depression and uncertainties in energy policy and in the geopolitical sphere. Since unstable energy policy increases the risk inherent in energy technology investment, a lack of stability would strengthen the normal alliance with the "tried and true." Prolonged international instability would probably have a similar effect. 8 PAGENO="0288" 282 C. The Future of Hydrogen It has been said that nations and individuals inevitably do the right thing but only after they have exhausted all the other possibilities.* Viewed in the abstract, ultimate conversion to a hydrogen/electric economy may very well be the long-term "right" thing for the United States. However, the hydrogen economy concept cannot be viewed solely in the abstract. If the concept is ever to be implemented, a feasible pathway linking the present--with its various established institutions, investments, interests, biases, and preferences--to the future must be found. It is not enough that hydrogen might be the best final solution, it would also have to be found the best transitional solution. An institutionally feasible pathway would be characterized by a series of small incremental changes (each of which may, nevertheless, be painful to some established interests) rather than a series of drastic changes. There is little doubt that as convenient fossil energy resources become exhausted, something like the hydrogen economy must eventually take form to accommodate mobile uses of energy. However, there is reason to debate when the transition should or must begin. Should it be decided that hydrogen is a goal to be pursued, then, ideally, interim changes in the energy economy should be in directions that would make a later transi- tion to a hydrogen less complex. However, there is a strong possibility that with a neutral governmental policy towards hydrogen, the series of incremental individual and corporate decisions will take the energy economy * Observed, without recalling the source, by Sir Siegmund Warburg in an interview: "Warburg: A European who Prefers Wall Street," Business Week (November 23, 1974), p. 92. 9 PAGENO="0289" 283 in a direction that will make a transition even more difficult than it would be today.* If adequate research and development is not performed to remove the uncertainties about hydrogen use and to improve the viability of the hydrogen economy concept, society may well find that it has, figuratively, painted itself into a corner because it had continued to make massive investments in expedient short-term solutions while neglecting to set, and make progress towards, long-term goals. Importantly, .a transition to hydrogen as a means to deliver energy to end users could be permanent because any primary energy resource developed in the future could be used to produce hydrogen. Thus, in the future, a sequence of basic energy resources could be utilized without ever again affecting consumers.~ In this respect, hydrogen offers a clear advantage to implementations of synthetic gasoline, diesel, methane, etc., because ultimately the carbonaceous resources on which these synthetics are based will be in short supply. Thus, while synthetic fuels from fossil resources ( would be easier to implement in the structural framework set by today's culture, they can only be a temporary solution and yet another transition will be required later. * For example, the development and deployment of coal liquefaction facilities to. produce a synthetic crude oil to maintain the viability of the existing petroleum-based system will not make a later transition to hydrogen less difficult. Instead this only adds to the complexity and to the entrenched investment of the hydrocarbon system. By contrast, investment in solar energy technologies, which will require means of energy storage (to tide over nighttime and unfavorable insolation conditions) would tend to advance the use of hydrogen storage systems and would also spur the delivery of the solar energy in hydrogen form. Therefore, this investment is one that would tend to make a future transition to hydrogen easier. Today, electric generation is about to embrace just such an increase in the diversity of its primary energy sources by using solar and geothermal energy. 10 62-332 0 - 76 - 19 PAGENO="0290" 284 D. Recommendations for Research and Development To preserve the option of choosing hydrogen as an important component of the energy economy of the future, significant research and development should be undertaken. However, the priorities for research and development options should take into account the transitional sequencing of the intro- duction of hydrogen production and use technologies that reflect real-world constraints in the existing institutional infrastructure. As a result, some potential research topics, such as further characterization of air pollutant emissions of internal combustion engines, could be shelved while awaiting progress in other, more fundamental areas such as low-cost, high- efficiency hydrogen production. If the lesson of the initiation and then cancellation of the SST program taught anything, it is that a clear distinction can and should be made between the decision to "explore" and the decision to "deploy" a techno- logical option. The following table gives a prioritized list of research and development topics that both reflects the need to explore some topics and the estimated criticality of any given topic in later decisions to deploy aspects of a hydrogen economy. The agency of government or the sector of private industry that seems best suited for leadership is indicated; the emphasis and priorities are taken to reflect the federal government point of view. :i~i PAGENO="0291" RECOMMENDATIONS FOR RESEARCH AND DEVELOPMENT High Priority (to begin at once) Sponsor 1. Development of Advanced concept hydrogen production technologies, NSF especially high pressure, high temperature electrolysis and closed- ERDA cycle thermochemical processes. This is the most critical area, Industry for without considerable cost reductions, all other questions about hydrogen are moot. 2, Development of advanced materials suitable for containing the high- NSF temperature, corrosive chemicals to be used in closed-cycle thermo- ERDA chemical processes. Without concurrent work on this topic, progress on part of topic 1 would be difficult. 3. Investigation of hydrogen-environment embrittlement in materials NSF expected to be used in the hydrogen economy under realistic con- ERDA ditions of temperature, pressure, and hydrogen purity. These NASA results are essential to avoid the study of inappropriate concepts DoD and to contribute to understanding of real hydrogen safety. 4. Rigorous analytical and experimental evaluation of hydrogen safety ERDA in likely applications in realistic environments under realistic DoT operational conditions. Once success was indicated in item 1; HEW safety would probably become the number one public concern. DoD 5. Determination (by social scientists) of the baseline public NSF-RANN attitude towards the use and safety of hydrogen followed by HEW periodic interviews (at 5- to 10-year intervals) to ascertain how and why attitudes towards hydrogen change. This research should begin at once, because valuable baseline data may be lost once the PAGENO="0292" High Priority (continued) Sponsor movie Hindenburg is released in late 1975. This information would be needed to develop a public education program to disseminate the results of topic 4. 6. Development of the air and ground systems need to support hydrogen- NASA fueled commercial passenger aviation. Research on this topic is apparently about to begin with NASA funding, it should continue. This is a high priority topic because aviation is one of the best candidate sectors for early transition to hydrogen. 7. Systems studies and detailed technology assessment of the intro- NASA duction of hydrogen into commercial aviation. This study should DoT include preparation of detailed implementation scenarios with the NSF-RANN assistance of stakeholders. Because massive government involvement seems essential and the lead times are long, key decisions may be needed in the next 6 to 10 years if this sector is to use hydrogen in the 1990s. 8. Evaluation of possible temporary or absolute materials resource Dol limitations of the hydrogen economy. The results of these studies ERDA are needed to guide development of advanced processes for hydrogen NSF-RANN production and consumption. This is a key topic intended to ensure that research and development money is spent only on technologies that could actually be deployed on a large scale. 9. Systems modeling of the U.S. energy economy to produce scenarios of ERDA hydrogen introduction that takes intb account hydrogen cost, inter- NSF-RANN fuel competition price relationships, environmental protection, and EPA institutional constraints. No completely adequate model yet exists CEQ to guide policy-making concerning the appropriate sequencing of conversion of energy use sectors to hydrogen. Results of this effort would allow development of a clear set of hydrogen research and development priorities. PAGENO="0293" High Priority (continued) Sponsor 10. Technological development of hydrogen reduction of iron ore. Industry Although this topic could be expected to contribute to the advancement of hydrogen production, environmental cleanup is the primary benefit. Medium Priority (to be begun when encouraging results have been obtained from high-priority topics) Sponsor 1. Examination of approaches to convert local methane distribution Industry pipelines to hydrogen use. FPC ERDA 2. Development of hydrogen energy storage systems suitable for use Industry by electric utilities for load-leveling applications. This is ERDA proceeding already with some industry findings. 3. Further examination of the institutional and economic barriers OTA to implementation; description of the incentive options that ERDA could surmount the barriers. This would amount to an in-depth NSF technology assessment of the concept. 4. Optimization studies of hydrogen economy building blocks based ERDA on the new research and development results obtained in other NASA topics mentioned. These wo~ild provide important input to the in-depth technology assessment suggested immediately above. 5. Demonstration flights of a cargo airplane converted to liquid NASA hydrogen fuel to gather operating experience and to test public acceptance of hydrogen. PAGENO="0294" U' Low Priority (to be held in abeyance until actual deployment is closer and the configuration of hydrogen technologies is better defined) Sponsor 1. Further demonstrations that existing automobile engines can be EPA operated on hydrogen and measurement of their pollutant emissions. ERDA 2. Study of hydrogen systems that use materials too scarce ever to be All sponsors useful on a large scale (for example, noble metal catalysts, rare- earth metal hydrides) unless these systems offer a significant advantage as a testing ground for studying general concepts or for obtaining fundamental scientific understanding. PAGENO="0295" 289 SECTION II TECHNOLOGY ASSESSMENT AND ENERGY IN ThE FUTURE Technology assessment as a public endeavor is still young but is gaining attention. Now that several assessments haye been attempted by various research teams, it is recognized that there can be no single appropriate method to approach such broad ranging studies. Rather, each technology (or family of technologies) requires a special tailor- ing of the study techniques to be applied. Only in this way can this form of study be responsive to the wide variation in the breadth and depth of societal consequences resulting from diverse technologies. This section briefly discusses the origins of technology assess- ment, some generalizations about the future of energy in this country, and the methods applied in this study. 16 PAGENO="0296" 290 CHAPTER 1--THE CONCEPT OF TECHNOLOGY ASSESSMENT The idea that many of the broad consequences of technological change might be anticipated in advance of their actual occurrence has gained acceptance in the past several years. Broad, systematic anticipation of future social, environmental, institutional, and economic effects is a relatively new endeavor, although forecasting in narrow subject or busi- ness areas has long been practiced. The process of attempting to foresee such impacts is now called technology assessmentl_9.* The first true technology assessments were sponsored and commissioned by the Research Applied to National Needs (RANN) Program of the National Science Founda- tion.1°'11 In 1974, the Office of Technology Assessment (OTA), a new government organization reporting to the U.S. Congress, also began to commission technology assessments.1° ,12,13 Generally, the goals of a technology assessment are to * Improve the level of information available to decision makers about the direct and indirect consequences of technological change. * Provide a point of departure for parties having a stake in the outcome of the change to voice their perceptions, attitudes, and concerns. *The process would be more generally understood if instead the name were technology impact assessment. - 17 PAGENO="0297" 291 * Identify policy or decision options that could improve the out- come of technological change by maximizing the beneficial and minimizing the detrimental aspects. The goals stated above have been articulated many times in similar state- ments by many people sponsoring or endeavoring to perform a technology assessment. The audience for technology assessments is broad and steadily in- creasing; it is generally recognized that the audience includes: * Decision makers in various levels of government - Legislative - Administrative * Decision makers in the private sector * The many publics, or groups, in the population, with a stake in the consequences. In addition, the technologists actively involved in development who fre- quently have not had the opportunity or inclination to assess the con- sequences of their professional activities is a long overlooked, but important, audience. The recent creation of OTA demonstrates that Con- gress has become aware of the increasing need to gauge the possible ramifications of legislative actions which increasingly concern tech- nology.2 The time scale for the evolution of technological change varies greatly depending upon the technologies involved. Some technologies possess the capability to cause great change in just a few decades (e.g., jet powered commercial aviation, transistors, and birth control pills). Other technologies have very long developmental lead times or protracted deployment schedules and the impacts develop slowly or become important only long after the technology is originally conceived (e.g., electric power, video telephones and space travel). The concept of an economy 18 PAGENO="0298" 292 which largely relies upon the use of hydrogen produced from primary energy sources to deliver energy, falls into the latter category. An economy fully dependent on hydrogen* is not likely to ever be reached, and widespread hydrogen use probably cannot reach its full flower before the mid 21st century. The performance of a technology assessment for such a distant tech- nology is handicapped both by the major uncertainties about the general state of society that far in the future and by uncertainties about the form of the technology that will actually be deployed. As a result, for distant technologies societal impacts descriptions must necessarily be rather general and imprecise and the public policy considerations must also remain rather general. For the hydrogen energy economy the pres- ently relevant policy issues are generally related to research and de- velopment activities that could reduce uncertainties and keep open the option of an eventual transition to a hydrogen energy economy. Accord- ingly, although this study is a preliminary technology assessment, such an early assessment provides an approved chance to plan, to adapt and to steer the evolution of the technology in question. *Or any other single energy form such as electricity. 19 PAGENO="0299" 293 REFERENCES 1. J. F. Coates, "Technology Assessment: The Benefits, the Costs, the Consequences," The Futurist (December 1971), PP. 225-231. 2. "Technology: Process of Assessment and Choice," report of the National Academy of Sciences to the Committee on Science and As- tronautics, House of Representatives, 91st Congress, 1st Session, July 1969. 3. "A Study of Technology Assessment," report of the Committee on Pub- lic Engineering Policy, National Academy of Engineering, to the Committee on Science and Astronautics, House of Representatives, 91st Congress, 1st Session, July 1969. 4. "Technical Information for Congress," report by the Science Policy Research Division, Legislative Reference Service, Library of Con- gress to the Subcommittee on Science, Research and Development of the Committee on Science and Astronautics, House of Representatives, 91st Congress, 1st Session, 1969. 5. R. G. Kasper, ed., Technology Assessment, Understanding the Social Consequences of Technological Applications (Praeger Publishers, New York, 1972). 6. H. Folk, "The Role of Technology Assessment in Public Policy," in Technology and Man's Future, A. H. Teich, ed. (St. Martin's Press, New York, 1972). 7. H. Brooks and R. Bowers, "Technology: Process of Asseasment and Choice," in Technology and Man's Future, A. H. Teich, ed. (St. Martin's Press, New York, 1972). 8. H. Brooks and R. Bowers, "The Assessment of Technology," Scientific American (February 1970), pp. 13-21. 9. H. V. Jones et al., "Technology Assessment," The Mitre Corporation (June 1971). 10. E. M. Dickson and R. Bowers, The Video Telephone, Impact of a New Era in Telecommunications (Praeger Publishers, New York, 1974). 20 PAGENO="0300" 294 11. J. F. Coates, "Technology Assessment and Public Wisdom, Journal of the Washington Academy of Science, Vol. 65, No. 1 (1975), pp. 3-12. 12. J. F. Burby, "Infant OTA Seeks to Alert Congress to Technological Impacts," National Journal Reports (21 September 1974), pp. 1418- 1429. 13. J. F. Burby, "OTA Works to Produce Track Record with Six Major Projects," National Journal Reports (28 September 1974), pp. 1454-1464. 21 PAGENO="0301" 295 CHAPTER 2--ENERGY AND HYDROGEN IN THE FUTURE A. Change is Inevitable Few people would argue that the world is entering an era of increased competition for the remaining fossil fuel resources, especially petroleum and natural gas.' Higher standards of living and increases in population increase the demand for energy. Moreover, as the richest metallic min- eral resources are depleted and ever leaner ores are mined and processed, energy must be consumed at an increasing rate just to sustain materials production for an industrial society. The day when technologies able to exploit unconventional sources of energy must be developed and deployed comes ever closer.1 There are many options available for meeting or altering future energy demands in both the near and long terms, including the following: * Introduction of energy conservation measures * Extended development of petroleum and natural gas supplies by - Tertiary recovery - Discovery and development on outer continental shelves, and under the deep sea - Discovery and development in remote land environments (e.g., Alaska). * Increased reliance on coal of various grades for - Direct combustion - Liquefaction into portable fuel - Gasification into pipeline quality fuel. 22 PAGENO="0302" 296 * Production of synthetic liquid fuels from unconventional fossil hydrocarbons - Oil shale - Tar sands. * Utilization of carbonaceous wastes - Municipal and industrial - Forest or agricultural - Sewage sludge. * Increased use of nuclear fission reactors for electricity generation - Conventional water-cooled - High temperature gas-cooled - Breeder reactors. * Development of nuclear fusion - Magnetic confinement of plasmas - Laser-induced. * Application of solar energy in many direct and indirect forms - Sunlight - Wind - Falling water (e.g., hydroelectric) - Ocean temperature differences - Biomass grown for use as a fuel. * Generation of electricity from geothermal energy - Natural steam and hot water reservoirs - Dry hot rock. Each of the above approaches to developing energy has its own local, temporal, environmental, or economic advantages and disadvantages (in- deed, the feasibility of some have not been demonstrated). No single approach is adequate or appropriate for all circustances. Certainly, in the future, as today, a multiplicity of resources, technologies, and techniques for providing energy will be used simultaneously. 23 PAGENO="0303" 297 B. Differences Between the Past and the Future The future will be different from the present in four very important ways: First, the world now depends almost entirely on fossil fuels, es- pecially petroleum, natural gas, and coal, which are readily storable and transportable (although coal, being a solid, is much less convenient for most applications than liquid petroleum products). However, increas- ingly, primary energy will be produced in forms that are neither portable nor storable. As a result, new emphasis will be placed on technologies that render unwieldy basic energy resources into convenient forms. Two prime examples are the proposed production of gaseous fuels from coal and the planned expansion in the use of nuclear fission energy to gen- erate electricity. Just as use of a multiplicity of basic energy re- sources can be expected in the future, so a multiplicity of energy sto- rage and carrier techniques can be expected. A second important way in which the future will differ from the present is that the large scale winning of energy from a basic resource, be it sunlight or underground fossil fuel deposits, will increasingly occur in places distant from the location of final demand. Often, as illustrated by Arabian oil, the basic energy resources will be beyond the political influence or protection of even the U.S. government. This, no doubt, will continue to give rise to sentiment favoring energy al- ternatives that would offer independence from foreign control as in the current planning for "Project Independence. "~ As international politi- cal situations ebb and flow, so certainly will the sentiment for energy independence. A third difference between the past and the future, for the United States at least, is the strong likelihood that continued emphasis will be placed on environmental quality, especially as it relates to energy production and end use. Pollution abatement procedures are often more 24 PAGENO="0304" 298 practical when undertaken on a large scale at a central facility than on the small scale that is characteristic of dispersed end uses. Therefore, strong pressures will exist to meet the twin needs of energy storage and portability with the energy forms that are cleanest in their end use characteristics. A fourth important difference is the certainty that some concen- trated deposits of carbonaceous materials of fossil origin will become physically exhausted and others will become uneconomic to recover. When such events begin to fall within planning horizons, strong incentives will arise for the development of nonfossil energy resources and com- pletely synthetic fuels.1 Ideal fuel or energy carriers would be sought that would meet these strong criteria: * Derived from inexhaustible, ubiquitous materials. * Convenient and efficient in production, distribution, storage, and use. * Environmentally clean in combustion or alternative uses. Because the United States possesses enormous resources and reserves of coal and oil shale, the time when domestic fossil resources are physi- cally exhausted is centuries away.1 However, less fortunately endowed nations (such as Japan) may be forced to consider nonfossil synthetic fuels much earlier, especially if depletion of their own resources is coupled with their own desire to achieve a measure of energy inde- pendence. C. The Possible Role of Hydrogen When the criteria for an ideal fuel are considered together in the abstract--inexhaustibility, cleanliness, convenience, independence from foreign control--it often seems to many people as if nature intended man- kind to use hydrogen as a fuel. In particular, hydrogen possesses these properties :29 25 PAGENO="0305" 299 * Derivable from any primary energy source. * Obtainable from water, a common substance. * Natural precipitation would recycle water between consumption and production. * Convenient to transmit and consume in gaseous form (the physical state at ambient temperatures and pressures). * Possible to transport and store as a cryogenic liquid (very low temperature). * Clean on combustion (oxidation), with harmless water the major exhaust product. Of course, there are qualifications to the above statements that make hydrogen, in reality, somewhat less than the ideal fuel. Nevertheless, it is easy to understand why numerous scientists, engineers, environmen- talists, and journalists have, especially since 1971, vigorously promoted the concept of the hydrogen energy economy.118 Much of their enthusiasm for the hydrogen economy concept seems to have originated in a search for a solution to automative air pollution.1024 Although "clean air" would be an important attribute of the hydrogen energy economy, other, more fundamental attributes are even more enticing. Before discussing the advantages of the hydrogen energy economy con- cept, it must be emphasized that hydrogen is not a basic energy resource. Hydrogen cannot be found chemically free in nature, and it cannot be ob- tained without the expenditure of some other energy form. Therefore, hydrogen must be considered an "energy carrier"--a means to transport and store energy derived from other sources. In this respect it would be analogous to electricity.2 D. Advantages of Hydrogen Probably the most attractive advantage in the use of hydrogen as an energy carrier comes from the ability to manufacture hydrogen from water using any primary energy resource. This means that hydrogen could 26 62-332 0 - 76 - 20 PAGENO="0306" 300 serve as a chemical common denominator in the energy economy. Electric- ity plays a similar role because many diverse primary energy resources can be used to generate it. In fact, the consumer has no way of knowing, and little reason to care, whether the electricity he uses was derived from falling water, coal combustion, wind, sunlight, nuclear power, or combustion of garbage. The common denominator aspect of electricity has greatly simplified matters for the consumer because the burden of any change or adjustment has been placed on the shoulders of the electric power utilities. Although these utilities do not make use of the full diversity of possible generation sources today, in the future they will probably be using various forms of solar energy-and geothermal energy not now generally feasible.1 Currently there is no common denominator in the total fluid or gaseous fuels economy. It could perhaps be argued, however, that in some major sectors of the economy a particular fuel essentially acts as a common denominator (for example, gasoline is the common fuel for cars of all makes and national origin). The possibility that a single fuel such as hydrogen could assume a common denominator role in the portable fuels arena analogous to the use of electricity for stationary applications is attractive. It is especially so since hydro- gen is derivable from water, which is an inexhaustible resource, and, hence, a transition to hydrogen could be permanent. An important aspect of using hydrogen as a common denominator fuel comes from its close relationships with electricity, the other common denominator energy form. As will be described later, hydrogen is most readily obtained from water by electrolysis; in reverse, hydrogen can be used to generate electricity either by combustion or in a device called a fuel cell. Thus, if hydrogen were to become a common denomi- nator fuel, there would be a great degree of interchangeability between the two common denominator forms of energy. This interchangeability 27 PAGENO="0307" 301 would offer many opportunities for economic, technological, and social benef it.3 E. The Need for a Technology Assessment In spite of the apparent attractiveness of hydrogen, its eventual widespread use is by no means assured. Its characteristics are very dif- ferent from the forms of energy people are accustomed to and there are near-term alternatives to it. People will evaluate the physics, chemis- try, economics, convenience, safety, implied institutional change, and so forth of all available alternatives. Hydrogen may well be viewed as inferior to the alternatives and be rejected. At an early stage, before either hydrogen or its alternatives are selected for eventual adoption, a technology assessment would be useful in illuminating various implications of a transition to a full or partial hydrogen energy economy. This study is the beginning of such an assess- ment effort and seeks to identify: * Technical barriers to the production, distribution, and use of hydrogen. * Benefits and risks. * Stakeholders (both knowing and unknowing) who have an interest in the forms of energy used in the future. * Uncertainties that can affect the forms of energy used. * Critical factors that will dominate the decision-making. o Strategies that can reduce uncertainties so that improved evaluations and decisions can be made. A hydrogen energy economy is constrained to a slow evolution because enormous changes face the nation in the area of energy, massive invest- ment has already been made in hardware for conventional energy activi- ties, and huge investment would be needed before significant amounts of hydrogen could be employed. Established infrastructures are resistant 28 PAGENO="0308" 302 to change and the temptation is continually strong to make only minor incremental modifications that will extend the lifetime of the existing order in preference to undertaking a major change.* Because of per- petual neglect, the state of the art in alternative systems usually lags far behind that of the dominant existing system, sometimes at the price of making even more difficult a transition that is recognized as ulti- mately necessary. Consequently, this preliminary assessment is largely concerned with the nature and implications of the transition process itself and the actions or policies that could help to preserve the option of an eventual transition to the hydrogen economy. *An example of this resistance to change can be found in the dominance of petroleum-derived gasoline in the private automobile sector. To sustain the existing distribution, manufacturing, and end-use invest- ments in the face of declining petroleum availability, the liquefaction of coal and conversion of oil shale to produce a synthetic gasoline is now receiving serious evaluation. However, relatively little consider- ation is being given to alternatives, such as electric cars powered by electricity derived from the same coal, that do not preserve the gaso- line distribution system and consumer investments. 29 PAGENO="0309" 303 REFERENCES 1. "Project Independence," Project Independence Report, Federal Energy Administration (November 1974). 2. D. P. Gregory et al., "A Hydrogen-Energy System," American Gas Association, Alexandria, Virginia (August 1972). 3. "Hydrogen: Likely Fuel of the Future," Chemical and Engineering News (26 June 1972), pp. 14-17. 4. "Hydrogen Fuel Use Calls for New Source," Chemical and Engineering News (3 July 1972), pp. 16-18. 5. "Hydrogen Fuel Economy: Wide Ranging Changes," Chemical and Engineering News (10 July 1972), pp. 27-29. 6. D. P. Gregory, "A New Concept in Energy Transmission," Public Utilities Fortnightly (3 February 1972), pp. 3-11. 7. D. P. Gregory, "The Hydrogen Economy," Scientific American (Janu- ary 1973), pp. 13-21. 8. T. H. Maugh II, "Hydrogen: Synthetic Fuel of the Future," Science, Vol. 178 (24 November 1972), pp. 849-852. 9. "Hydrogen and Other Synthetic Fuels," a summary of the work of the Synthetic Fuels Panel, prepared for the Federal Council on Science and Technology R&D Goals Study (September 1972). 10. L. Lessing, "The Coming Hydrogen Economy," Fortune (November 1972), pp. 138-146. 11. "Fuel of the Future," Time (11 September 1972), p. 46. 12. "The Wonder Fuel," Newsweek (12 November 1973), p. 75. 13. L. W. Jones, "Liquid Hydrogen as a Fuel," Science, Vol. 174 (22 October 1972), pp. 367-370. 30 PAGENO="0310" 304 14. "When Hydrogen Becomes the World's Chief Fuel," Business Week (23 September 1972), pp. 98-102. 15. W. Clark, "Hydrogen May Emerge as the Master Fuel to Power a Clean Air Future," Smithsonian (August 1972), pp. 13-18. 16. G. D. Brewer, "The Case for Hydrogen-Fueled Transport Aircraft," Astronautics and Aeronautics (Hay 1974), pp. 40-51. 17. L. T. Blank et al., "A Hydrogen Energy Carrier," Systems Design Institute, National Aeronautics and Space Administration-American Society for Engineering Education, Johnson Space Center, Houston, Texas (1973). 18. L. W. Jones, "Liquid Hydrogen as a Fuel for Motor Vehicles: A Comparison with Other Systems," 7th Intersociety Energy Conversion Engineering Conference, 1972, pp. 1364-1365. 19. R. G. Murray, R. J. Schoeppel, C. L. Gray, "The Hydrogen Engine in Perspective," 7th Intersociety Energy Conversion Engineering Con- ference, 1972, pp. 1375-1381. 20. M. R. Swain and R. H. Adt, "The Hydrogen-Air Fueled Automobile," 7th Intersociety Energy Conversion Engineering Conference, 1972, pp. 1382-1387. 21. W.J.D. Escher, "On the Higher Energy Form of Water (H20*) in Automotive Vehicle Advanced Power Systems," 7th Intersociety Energy Conversion Engineering Conference, 1972, pp. 1392-1402. 22. L. 0. Williams, "The Cleaning of America," Astronautics and Aero nautics, Vol. 10, No. 2 (February 1972), p. 42. 23. P. B. Dieges et al., "An Answer to the Automotive Air Pollution Problem. . . The Hydrogen and Oxygen Fueling System for Standard Internal Combustion Engines," First Annual Report of the Perris Smogless Automobile Association, Perris, California (undated). 24. W.J.D. Escher, "The Case for the Hydrogen-Oxygen Car," in The Analog Science Fact Reader (St. Martin's Press, New York, 1974). 31 PAGENO="0311" 305 CHAPTER 3--METHODS OF THE STUDY The technique used in this study is a semiquantitative form of systems analysis. The construction of simple systems diagrams of the various technologies of a possible hydrogen energy economy and their possible niche in U.S. society made it possible to trace the flow of materials, energy, and money through the relevant energy systems. This process greatly aided the identification of stakeholders (both those who know of their future involvement and those who do not), transac- tions, the things of value transacted, the forces or institutions that regulate them, and the factors on which decisions are likely to be based. Seven major resources served this study: * The vast body of literature on a hydrogen economy that has developed in the last few years.* * Four national meetings at which the hydrogen economy was either a major or the sole topic. * Discussions at these meetings with many authors of relevant papers in the literature. * Discussions with experts and visits to installations. *This literature, however, turns out to be largely secondary in nature. Only a very few primary references seem to have spawned a great flurry of cross citations. The number of papers with something truly new to say has actually been rather small until this past year (1974-1975). The bibliography presented at the end of this chapter lists some of the most comprehensive reference materials. 32 PAGENO="0312" 306 * Services of a consultant* widely known among hydrogen economy enthusiasts who offered critical comments and facilitated personal contacts. * Discussions with professionals on the SRI staff with pertinent expertise. * Simultaneous involvement in a technology impact assessment of deriving synthetic liquid fuels (oils and methanol) from coal and oil shale. It became clear early in the study that a major component of the study would be development of scenarios depicting the possible implementation of the hydrogen energy economy concept. It was also clear that these scenarios had to be more realistic than the wishful thinking that per- vades the literature. As will be detailed in Chapter 13, after the technical and economic background has been presented, the implementation of even a portion of a hydrogen energy economy would be slow and costly and would involve institutional changes. Advocates of a hydrogen econ- omy commonly fail to distinguish between end points (when the conversion of specific sectors are essentially completed), and the period of tran- sition. It was readily determined early in the study that the end points are a very long time away (well into the twenty-first century). Conse- quently, most of the study had to be concerned with transitions in vari- ous sectors. However, description and consideration of the end points proved to be a useful guide to the form and impact of the transition process. Technologies encounter physical limitations and exhibit economies of scale. The optimally sized unit, or "natural building block," char- acteristically has reaped nearly all of the economy of scale benefits possible and has been standardized in its manufacture. Rather than *Mr. W.J.D. Escher of Escher Technology Associates, Inc., St. John's, Michigan. 33 PAGENO="0313" 307 build a device or system twice as large as the natural building block, two building blocks are built in parallel. Good examples of the natural building block concept are railrbad boxcars, petroleum storage tanks, and 1000-Megawatt (equals 1 Gigawatt [Gw] ) nuclear reactors. To formu- late the transition scenarios, it proved useful to describe the physical systems in terms of natural building blocks. (See Chapter 13.) Once system components have been described in terms of natural building blocks, it is often found that conceivable systems are not practical. In particular, a system that seems sensible when considered only as `A feeds into B which feeds in C" loses credibility once it is observed that the natural sizes of A and C do not match the natural size of B. Mismatches between the natural building block components of the hydrogen energy economy were found in abundance; this suggests that the implementation of the concept may be greatly impeded. Thus, the use of the natural building blocks in systems diagrams have been used to identify: * Physical bottlenecks * Institutional barriers or conflicts * Economic barriers. In Chapter 13 scenarios will be shown that depict several imple- mentation conditions: * Optimistic, assuming no government intervention, ignoring hydrogen's economic disadvantage, and assuming minimum decision and technology lead times. * Realistic, assuming some government involvement in decision- making, some improvement in hydrogen's cost relative to alter- natives, and less optimistic lead times. * Strong government intervention, assuming federal government mandates the use of hydrogen, backed by appropriate barriers and incentives. 34 PAGENO="0314" 308 These scenarios make clear that within the time frames that can be sensibly foreseen, a hydrogen economy remains in a "transition period." These scenarios form the basis for this study's analysis of societal impacts that have been identified by reflection on the structure of the economy and society as well as by observations of societal response to suggestively similar events. 35 PAGENO="0315" 309 BIBLIOGRAPHY Major Information Resources 1. D. P. Gregory et al., `A Hydrogen-Energy System," American Gas Association, Alexandria, Virginia (August 1972). 2. "Hydrogen and Other Synthetic Fuels," a summary of the work of the Synthetic Fuels Panel, prepared for the Federal Council on Science and Technology R&D Goals Study (September 1972). 3. E. Fein, "A Hydrogen Based Energy Economy," The Futures Group, Glastonbury, Connecticut (October 1972). 4. L. T. Blank et al., "A Hydrogen Energy Carrier," Systems Design Institute, National Aeronautics and Space Administration-American Society for Engineering Education, Johnson Space Center, Houston, Texas (1973). 5. G. D. Brewer, et al., "Study of the Application of Hydrogen Fuel to Long Range Subsonic Transport Aircraft," National Aeronautics and Space Administration, Langley Research Center, Langley Station, Virginia (January 1975). Major Collections of Papers 6. 5. Linke, ed., Proceedings of the Cornell International Symposium and Workshop on the Hydrogen Economy (Cornell University, Ithaca, New York, April 1975). Forty-five papers. 7. T. N. Veziroglu, ed., Hydrogen Energy, Proceedings of the Hydrogen Economy Miami Conference, Miami Beach, Florida, 1974 (Plenum Press, New York, 1975). Eighty papers. 8. 7th Intersociety Energy Conversion Engineering Conference, San Diego, California, 25-29 September 1972. Seven papers. 9. 9th Intersociety Energy Conversion Engineering Conference, San Francisco, California, 26-30 August 1974. Nine papers. 36 PAGENO="0316" 310 10. T. N. Veziroglu, ed., "Hydrogen Energy Fundamentals, A Symposium Course," 16 papers presented at the University of Miami, Florida, 3-5 March 1975. Semipopular Reviews 11. T. H. Maugh II, "Hydrogen: Synthetic Fuel of the Future," Science, Vol. 178 (24 November 1972), pp. 849-852. 12. D. P. Gregory, "The Hydrogen Economy," Scientific American (Janu- ary 1973), pp. 13-21. 13. "Hydrogen: Likely Fuel of the Future," Chemical and Engineering News (26 June 1972), pp. 14-17. 14. "Hydrogen Fuel Use Calls for New Source," Chemical and Engineering News (3 July 1972), pp. 16-18. 15. "Hydrogen Fuel Economy: Wide Ranging Changes," Chemical and Engi neering News (10 July 1972), pp. 27-29. 16. L. Lessing, "The Coming Hydrogen Economy," Fortune (November 1972), pp. 138-146. 17. W. E. Winsche et al., "Hydrogen: Its Future Role in the Nation's Energy Economy," Science, Vol. 180 (29 June 1973), pp. 1325-1332. Abstracts and Listing of Literature 18. K. H. Cox, ed., "Hydrogen Energy: A Bibliography with Abstracts," The Energy Information Center, University of New Mexico, Albuquer- que, N. H. (1 January 1974). 19. "Hydrogen, Future Fuel," Cryogenic Data Center, National Bureau of Standards, Boulder, Colorado (Quarterly). 37 PAGENO="0317" .311 SECTION III HYDROGEN TECHNOLOGIES--PRESENT AND PROJECTED In describing hydrogen economy technologies and conceivable systems, we have tried to strike a balance between technical complexity and sim- plicity so that this single report may be informative to those with a wide range of backgrounds. Excellent descriptions of much of the fol- lowing material can be found in the literature, but we feel that it is important that this report to be self-contained. Readers who desire or need more technical depth than that presented here should consult the references. 38 PAGENO="0318" 312 CHAPTER 4--HYDROGEN PRODUCTION A. Sources of Hydrogen Because hydrogen is chemically very reactive, it is not found in its elemental state on the earth. However, combined chemically with other elements, it is present in: * Water (the most abundant hydrogen resource) * Fossil hydrocarbons - Coal - Petroleum - Natural gas - Oil shale * Biological materials - Carbohydrates - Protein * - Cellulose * Minerals (such as bicarbonate rocks) Energy must be supplied to release hydrogen from any of these compounds by breaking the chemical bonds. Thus hydrogen is not a primary energy resource obtainable from nature in the same manner as petroleum or coal. Instead, hydrogen is properly regarded as an energy carrier or a means to store and transmit energy derived from a primary energy resource. Hethods of obtaining hydrogen are described below. 39 PAGENO="0319" 313 B. Hydrogen Production from Fossil Fuels Fossil hydrocarbons contain hydrogen and carbon atoms in varying ratios and can be used as a source of hydrogen.1 Table 4-1 shows the atomic hydrogen to carbon ratio for several of the more important and abundant hydrocarbons .~ Table 4-1 ATOMIC HYDROGEN/CARBON RATIO FOR SOME ABUI~DANT HYDROCARBONS Atomic H/C Ratio Methane (CH4) 4 Petroleum (heavy fuel oil) 1.5 -1.6 Oil shale 1.6 Coal 0.72-0.92 Ironically, the most favorable hydrogen to carbon ratio is found in methane, Cl!4, the major component of natural gas, a fuel that hydrogen might ultimately supplant. Today, relatively little hydrogen is used compared to the requirements of a mature hydrogen economy and much of it is obtained by decomposing methane and steam by a process called "reforming."1 Half of the hydrogen is derived from the steam. Reformation of methane consists of a series of chemical reactions involving methane, water (steam), and a catalyst; heat must be supplied. In effect, the hydrogen is stripped out of both the methane and the water molecules; the reject carbon and oxygen are discarded in the form of carbon dioxide, CO2. Reformation processes can be termed to be "open- cycle" thermochemical production methods. The chemical steps for 40 PAGENO="0320" 314 reforming methane are shown in equation form in Table 4-2. This reform- ing process is only about 70 percent efficient when all the energy in- puts needed to achieve the complete reformation are considered. Other hydrocarbons can also be reformed to produce hydrogen by similar proc- esses. Table 4-2 CHEMISTRY OF THE STEAM-REFORMING OF HEThANE Reforming reaction: CH4 + H2O -, CO + 3 H2 Shift reaction: CO + H20 -, CO2 + H2 Net reaction: CH4 + 2 H20 + heat -~ CO2 + 4 H2 Hydrogen produced from methane is the source of the liquid hydrogen rocket propellant used by the U.S. space program and gaseous hydrogen used to synthesize ammonia.2 About 75 percent of ammonia is used in agriculture for fertilizer.2 Because reserves of methane are declining while demand continues to increase, methane cannot be considered avail- able for long-term, large-scale production of hydrogen. Hydrogen obtained from coal is expected to be the lowest cost, large-scale source of hydrogen (not based on oil or methane) for many years (see Chapter 11). Coal gasification must be considered one of the key technologies if implementation of a hydrogen economy is to begin in this century. Although coal gasification was developed years ago, it is currently undergoing improvement and is about to be deployed in the first modern large commercial plants. However, most R&D effort and investment commitment to coal gasification have been directed toward 41 PAGENO="0321" 315 the production of methane for use as a substitute natural gas (SNG).* Thus, technical modifications needed to produce hydrogen instead of methane are relatively simple and well understood. The impetus for SNG development came from the natural gas industry, especially the pipeline companies and utilities, as a means to offset declines in the supply of domestic natural gas. relative to demand. The emphasis has been on the production of methane rather than hydrogen be- cause SNG could be mixed into the supplies of natural gas directly. This would result in an essentially unchanged product delivered to the consumer and an unchanged delivery system. Hydrogen could not be blended into the energy supply as simply because the energy contained per unit of volume of hydrogen is only about one-third that of methane. Furthermore, the physical and chemical properties of hydrogen differ from methane, and this would make it awkward for the consumer because changes in his gas burners would be required.3 The variation in energy content, or `heating value," of fuel gases has led to phrases to describe the gas such as high heating value, high Btu, low heating value, low Btu, and pipeline quality.1 The various definitions are shown in Table 4-3. "Pipeline quality" indicates that all the properties of the gas approximate those of natural gas and that therefore the gas can be readily mixed with existing natural gas sup- plies. Low heating value gas often contains substantial quantities of carbon monoxide (CO) which has nearly the same heating value as hydro- gen. Because this gas mixture has a low energy content per unit weight, it is uneconomical to transport in pipelines; consequently, it is usu- ally consumed close to the site of production.1 *The abbreviation SNG originallymeant "synthetic natural gas;" now, however, SNG is usually said to mean "substitute natural gas." 42 62-332 0 - 76 - 21 PAGENO="0322" 316 Table 4-3 COMMON GAS NOMENClATURE Approximate Energy Content* Common Name (Btu/SCFt) * High heating value High Btu 900-1000 Pipeline quality * Low heating value I 100 -500 Low Btu * Methane (CM4) 1000 * Hydrogen (H2) 325 * Carbon monoxide (CO) 322 *Higher heating values. fStandard cubic foot. One of the coal gasification processes that yields a hydrogen prod- uct is depicted in Figure 4-1. This is one of the most likely processes to be used in the future. Other process descriptions can be found in Reference 1. To date, only pilot SNG plants are in operation although some plans are being made to construct commercial plants in the near future in the Four Corners area of New Mexico and in North Dakota.4 Considerable water is used consumptively by these processes, both as a source of hydrogen and for cooling. Availability of water is an im- portant constraint to the conversion of western coal resources. 43 PAGENO="0323" a a FIGURE 4-I. TYPICAL HIGH TEMPERATURE, ATMOSPHERIC PRESSURE COAL GASIFICATION PROCESS GASIFICATION C+ ~O2-..CO+HEA C+H20 - CO+ H2 CO+H20-CO2÷H2 PAGENO="0324" 318 C. Hydrogen from Water by Electrolysis The electrolysis of water (H20) to produce both hydrogen and oxygen is demonstrated in every high school chemistry course. This approach to hydrogen production has been well known for many years and the hydrogen produced is quite pure.1'~'615 However, until lately little effort has been made to improve energy efficiency or cost of the process. Rela- tively little* hydrogen has been produced commercially by electrolytic processes because for decades when large quantities have been needed it has been more economical and more convenient to obtain hydrogen by re- forming methane or oils.2 The reliability and simplicity of unattended operation of electrolysis equipment rather than its energy efficiency have been the prime design considerations because the low level of com- mercial interest in this process did not provide economic incentive to the performance of innovative R&D. As a result, commercial electrolyzers have been small and relatively inefficient, and the technology has been rather stagnant. Commercially available electrolysis cells operate in the range of 60 to 70 percent efficiency.9 The rest of the energy is lost in driving the electric current through the cell; this loss is manifested as heat. The need to provide electric power aboard manned and unmanned space- craft has led to the development of fuel cells1~--device5 in which cer- tain chemical reactions generate an electric current.1a,l? The basic reac- tion is the catalytic oxidation of hydrogen rather than combustion; the end product is water, and some heat. The electrochemistry in electro- lyzers and in fuel cells is essentially identical--indeed, the processes *Total world-wide electrolytic production of hydrogen is only equivalent to about 3 percent of current U.S. total production of hydrogen. tAlso silicon photovoltaic solar cells. 45 PAGENO="0325" 319 are basically the inverse of one another.3'18 As a result, in prin- ciple, it is possible to build a single device that can function both as an electrolyzer or a fuel cell depending on whether it was operated in the "forward' or "backward" mode. Such a device is sometimes called a "reversible fuel cell." Although such a device might sound attractive for a hydrogen energy economy, a combined device is not very practical because obtaining a very effective electrolyzer or a very effective fuel cell requires an engineering optimization of conflicting variables. Thus, a good fuel cell is a poor electrolyzer and vice versa. Conse- quently, electrolyzers and fuel cells will almost certainly remain dis- tinct entities in most practical applications. In the last few years increased R&D effort has been directed to- ward development of more efficient electrolyzers. It is generally agreed that improved electrolyzer efficiencies can be obtained by the use of higher temperatures and higher pressures of operation.3 Separate experi- ments and demonstrations have reported operating temperatures of 2OOO°F~ and hydrogen and oxygen evolution pressures of 3000 psi.13 Unfortu- nately, however, as might be expected, operation at high pressures and temperatures has uncovered previously unexperienced materials problems such as membrane and gasket degradation, which limit the useful lifetime of the cells. Electrochemists and metallurists generally expect that the materials problems of electrolysis and fuel cells can be solved not only on experimental device scale but also on the commercial scale. The efficiency of electrolysis is normally defined as the energy that ideally could be recovered by reoxidation of the hydrogen and oxy- gen coproducts to water divided by the energy supplied to the electrol- ysis system in electrical form;3 this definition is shown in Figure 4-2. Since electrolysis involves an endothermic (i.e., heat must be added) chemical reaction, a perfect electrolyzer would consume both electricity and heat. Yet because this heat input is not counted in the usual 46 PAGENO="0326" 320 NOTE: FOR PRESENT PRACTICAL CELLS THE DIRECTION OF HEAT FLOW IS REVERSED OWING TO ELECTRIC CURRENT RESISTANCE LOSSES IN CELL. EFFICIENCY = HEATING VALUE OF HYDROGEN OUTPUT ENERGY OF ELECTRICAL INPUT * FIGURE 4-2. IDEAL ELECTROLYSIS CELL AND CONVENTIONAL DEFIN IT1ON OF ELECTROLYSIS EFFICIENCY definition of efficiency, the hydrogen product of a perfect electrolyzer would contain more energy than had been supplied in electrical form. Indeed, the maximum theoretical efficiency--using this definition--is 120 percent.3* To date, in real world electrolyzers, as opposed to *Because electrolyZers and fuel cells share the same electrochemistry, the same considerations that allow a perfect electrolyzer to have an efficiency of 120 percent limit the efficiency of a perfect fuel cell to about 84 percent.3 47 PAGENO="0327" 321 ideal electrolyzers, resistance to the flow of electric current and other losses in the electrolysis cell still result in a net release, rather than an absorption, of heat. Such resistance would have to be nearly completely eliminated before an electrolysis cell could be used as a heat sink. However, should technology .ever advance to that point, the heat input might be derived from the waste heat of the power plant that generated the electricity used in the electrolysis cell. One of the most attractive attributes of electrolytic production of hydrogen is the small "natural" size of the practical cell. Because many cells would be cascaded and paralleled in a commercial installa- tion, the plant output could be tailored to virtually any level of out- put without sacrificing important economies of scale. In Chapter 12 it will become apparent that this flexibility in size provides electrolysis with a versatility not readily obtained in other forms of hydrogen pro- duction. Catalysts are such a necessary part of advanced, high efficiency electrolytic cells18 that the future availability of catalytic materials on a large scale is important. Some of the experimental cells use plat- inum or other rare noble metals for catalysts,18 although nickel is sometimes employed.9 In commercial applications nickel compounds are the most likely future catalyst of choice. However, nickel is not a very abundant metal, and the United States currently imports about 70 percent of its needs--about 58 percent of it from Canada.19 Because there are many other uses for nickel, such as in high strength steels and other alloys, the availability of nickel has to be considered.19 Depending on the level of electrolytic production of hydrogen, however, the avail- ability of nickel for catalysts may not develop into a problem. For example, the Synthetic Fuels Panel report estimates that an annual 48 PAGENO="0328" 322 production of about 15 x 1012 SCF of hydrogen (the Panel's estimate* of the gap between domestic natural gas supply and demand in 1985) would require only about 1500 tons of nickel9 --a small amount compared with the 1972 U.S. primary production of about 16,000 tons and world produc- tion of 700,000 tons.2° D. Closed-Cycle Thermochemical Decomposition of Water If water is heated to a high temperature, such as 2000°C (about 3600°F) a small fraction (about 4 percent) of the molecules decompose into hydrogen and oxygen.21 Such temperatures are far too high, and the quantities far too small, to lend encouragement to the concept of direct, single step decomposition of water on a commercial scale. How- ever, some ingenious multiple-step, closed-cycle, chemical processes have been devised that may effectively use heat to decompose water on a commercial scale.~'~'2133 The basic idea is that by several chemical reaction steps water can be broken into its hydrogen and oxygen constituents with all the other, intermediate, reactants being continuously recycled. Figure 4-3 shows how the scheme can be viewed as splitting water by the application of heat and the equations of the Mark xi thermochemical water decomposition process22'29 developed at the Euratom facility at Ispra, Italy. Many other cycles are now being ~nvestigated.t Although the first cycles to *There is a numerical inconsistency in the Panel's figures; they state 15 x 1019 where they mean 15 x 1012. ~By research groups at Euratom, General Atomic, General Electric, the Institute of Gas Technology, Lawrence Livermore Laboratory, Argonne National Laboratory, Oak Ridge National Laboratory, Los Alamos Na- tional Laboratory, and the University of Kentucky. 49 PAGENO="0329" 6 FeCL2+8H20 2 Fe3 04+ 12 HC2~ + 2H2 2 Fe304+ 3CL2+ 12 HC~ -`- GFeCL3+6H20+02 6 FeC~3-~~. 6FeC~2+ 3CL2 NET: 2H20-ų-2H2+02 FIGURE 4-3. SCHEMATIC OF CLOSED CYCLE THERMOCHEMICAL WATER SPLITTING AND EQUATIONS OF THE EURATOM MARK IX CYCLE 323 EURATOM MARK IX PROCESS TEMPERATURE (650°C) (120°C) (420°C) 50 PAGENO="0330" 324 be announced were devised by the combination of ingenuity and intuition, the search for usable cycles has been broadened and computerized at Gen- eral Atomic.31 The many possible combinations of chemical reactions are now being screened with respect to chemical or practical constraints. Very high temperatures are usually required for one or more steps in the cycle--often in excess of 700°C (1300°F). At present, only two (nonfossil fueled) methods of sustaining such temperatures offer much promise--the high temperature gas cooled nuclear reactor (HTGR)34'36-- and highly focused solar radiation.36 At the temperatures involved, much of the basic physical chemistry data necessary to evaluate the cycles fully have never been measured. Considerable laboratory research is needed to establish the thermodynamics and kinetics of the main reac- tions in even the most promising cycles and approaches to the suppres- sion of spurious parasitic chemical side reactions are needed as well. In addition, considerable further research is needed to understand and manage the materials problems that arise in attempting to contain the reactions without destructive corrosion of containment vessels and con- tamination of the chemical reactants. Apparently, for only a few cycles have even bench tests been performed on all steps. A potentially serious, but seldom mentioned, drawback to closed- cycle thermochemical production arises because the cycles are unlikely to be truly closed. Instead, there will be some loss of reactants, and, at the quantities of hydrogen production implied by the hydrogen econ- omy concept, even the loss of a fraction of one percent per cycle would release large amounts of reactants. Some of the reactants proposed, such as mercury, cause undesirable environmental effects. Why then, in light of the difficulties and uncertainties mentioned, is there attraction to the thermochemical decomposition of water in pref- erence to electrolysis of water? The answer lies in the projected net 51 PAGENO="0331" 325 energy efficiencies of the thermochemical processes. Some hope to achieve a net efficiency of thermochemical water decomposition of about 70 percent. Researchers who have tried to estimate and deduct the energy expended in the chemical separations, pumping, and so forth, have con- cluded that the upper limit of net energy efficiency will be about 55 percent,23 Nevertheless, a net efficiency of 55 percent is greater than the projected net efficiency of 36 percent for electrolysis (40 percent thermal efficiency for electricity generation from an HTGR cascaded with electrolysis at 90 percent efficiency).* Thus, achievement of a practi- cal cyclic thermochemical decomposition process might make hydrogen pro- duction less energy consuming, and possibly less expensive as well. Because the financial rewards for achieving and patenting a process could be very substantial, the interchange of thermochemical cycle in- formation is considerably more guarded than in most other hydrogen econ- omy subject areas. Probably more private sector R&D money has now been devoted to this portion of the hydrogen energy than to any other.t E. Mixed Thermal/Electrolytic Some hydrid cycles that combine thermochemical and electrolytic ap- proaches are now being considered. Table 4-4 depicts a sulfur-based cycle being investigated at Westinghouse. Such approaches have received relatively little serious attention. *However development of more advanced power generation cycles may raise the efficiency of power generation thereby making electrolysis a bit more competitive. fGeneral Atomic in particular seems to have much to gain because devel- opment of a commercial process would almost certainly give a major sales boost to its newly commercialized HTGR--a reactor with no U.S. commer- cial competitors. 52 PAGENO="0332" 326 Table 4-4 WESTINGHOUSE HYBRID CYCLE Electrolysis 2 1120 ÷ SO2 -, H2S04 + H2 Thermal 2 H2S04 -. 2 H20 + 2S02 + 0~ Net reaction: 2 H20 -+ 2 H~ + 02 F. Hydrogen from Thermonuclear Fusion Poorly documented news reports have appeared in scientific magazines stating that KMS Fusion Corp. (in Ann Arbor, Michigan), the only private company to have made notable progress in the achievement of thermonuclear fusion with high-powered lasers, has a process by which hydrogen and/or methane could be made directly in a laser fusion reactor.37 It is ru- mored that the process involves direct splitting of water with neutrons. G. Comparison of Hydrogen Production Processes The advantages and disadvantages of the three major hydrogen produc- tion approaches are summarized in Table 4-5. A very important advantage of electrolysis, in spite of its expected higher cost and relative inef- ficiency, is its avoidance of dependence on any fossil energy resource (unlike coal gasification) and its ability to operate at temperatures much lower than thermochemical cycles. In addition, small practical unit size and low voltage requirements of electrolysis suit it very well for integration into terrestrial solar energy collection systems, parti- cularly photovoltaic, thermal-electric, ocean thermal gradient, and 53 PAGENO="0333" 327 Table 4-5 COMPARISON OF HYDROGEN PRODUCTION ALTERNATIVES Process Advantage Reformation of Presently the cheapest methane method Scant long-term potential as a source because of limitations on methane supply. Coal gasifica- tion Cheapest and most secure near-term alternative to methane reformation; abundant coal reserves in United States. Ultimate limitation is ex- haustion of the coal re- source; requires large plant size. Electrolysis Proven reliable technol- of water ogy; small unit plant size; well suited to all terrestrial solar energy collection approaches; oxygen coproduct, easily separated for possible use and economic credit improves the economics; improvements in efficiency quite likely; can produce hydrogen at high pressures thereby eliminating the need for costly compres- sion to pipeline pressures. High cost, lower net energy efficiency, pos- sible resource limita- tion on catalysts Thermochemical decomposition Potentially most efficient nonfossil processes; not tied to fossil fuel re- sources; possibly com- patible with high tem- perature, focused solar collectors. Not a proven technology; materials problems in containment; complex large unit plant size ex- pected; expected release of potentially harmful chemicals. Disadvantage 54 PAGENO="0334" 328 windpower.* The already very low efficiency (15 to 20 percent) of elec- tric generation from geothermal sources37 argues against subsequent fur- ther net energy loss through electrolytic production of hydrogen until very efficient electrolysis is developed. Because of the temperature of geothermal resources, there is little prospect for geothermal energy being used for thermochemical decomposition of water. *In fact, some of these solar energy technologies may become viable only if wedded to hydrogen energy storage systems used to smooth out the vari- ations in production. 55 PAGENO="0335" 329 REFERENCES 1. H. C. Hottel and J. B. Howard, New Energy Technology, Some Facts and Assessments (MIT Press, Cambridge, Massachusetts, 1971). 2. P. Meadows and J. A. DeCarlo, "Hydrogen," in Mineral Facts and Prob lems, Bureau of Mines Bulletin 650 (1970). 3. D. P. Gregory et al., "A Hydrogen-Energy System," American Gas As- sociation, Alexandria, Virginia (August 1972). 4. H. R. Linden, "Is the Synthetic Fuels Option Credible?" paper pre- sented at the 3rd National Energy Forum, Washington, D.C., 15-16 May 1975. 5, M. Steinberg, "A Review of Nuclear Sources of Non-Fossil Chemical Fuels," paper presented at the meeting of the American Chemical Society, Boston, Massachusetts, 9-14 April 1972. 6. R. L. Costa and P. G. Grimes, "Electrolysis as a Source of Hydrogen and Oxygen," Chemical Engineering Progress, Vol. 63, No. 4 (April 1967), p. 56. 7. W. Juda and D. M. Moulton, "Cheap Hydrogen for Basic Chemicals," Chemical Engineering Progress, Vol. 63, No. 4 (April 1967), pp. 59-60. 8. N. C. Hallet, "Study, Cost, and System Analysis of Liquid Hydrogen Production," National Aeronautics and Space Administration Circular #73226 (June 1968). 9. "Hydrogen and Other Synthetic Fuels," a summary of the work of the Synthetic Fuels Panel, prepared for the Federal Council on Science and Technology R&D Goals Study (September 1972). 10. W. A. Titterington and A. P. Fickett, "Electrolytic Hydrogen Fuel Production With Solid Polymer Electrolyte," 8th Intersociety Energy Conversion Engineering Conference, 1973, pp. 574-579. 56 PAGENO="0336" 330 11. "Solid Electrolytes Offer Route to Hydrogen," Chemical and Engi neering News (27 August 1973), P. 15. 12. F. C. Jensen and F. H. Schubert, `Hydrogen Generation Through Sta- tic Feed Water Electrolysis," in Hydrogen Energy, T. N. Veziroglu, ed. (Plenum Press, New York, 1975), pp. 425-440. 13. L. J. Nutall et al., "Hydrogen Generation by Solid Polymer Elec- trolyte Water Electrolysis," in Hydrogen Energy, T. N. Viziroglu, ed. (Plenum Press, New York, 1975), pp. 441-456. 14. J. B. Laskin, "Electrolytic Hydrogen Generators," in Hydrogen Energy, T. N. Veziroglu, ed. (Plenum Press, New York, 1975), pp. 405-416. 15. J. O'M. Bockris, "On Methods for the Large Scale Production of Hy- drogen from Water," in Hydrogen Energy, T. N. Veziroglu, ed. (Plenum Press, New York, 1975), pp. 371-404. 16. T. H. Haugh, II, "Fuel Cells: Dispersed Generation of Electricity," Science, Vol. 178 (22 December 1972), pp. 1273-l274B. 17. A. J. Appleby, "Fuel Cells and Electrolyzers in the Hydrogen Econ- omy," in Proceedings of the Cornell International Symposium and Workshop on the Hydrogen Economy, S. Linke, ed. (Cornell University, Ithaca, New York, April 1975), pp. 197-211. 18. E. E. Hughes et al., "Strategic Resources and National Security: An Initial Assessment," RADC-TR-75-54, Defense Advanced Projects Research Agency, Rome Air Development Center, Rome, New York (April 1975) 19. Statistical Abstract of the United States, 1974, Bureau of the Census, U.S. Department of Commerce (July 1974). 20. L. T. Blank et al., "A Hydrogen Energy Carrier," Systems Design Institute, National Aeronautics and Space Administration-American Society for Engineering Education, Johnson Space Center, Houston, Texas (1973). 21. G. DeBeni, "Thermochemical Water Splitting with Nuclear Heat, in Proceedings of the Cornell International Symposium and Workshop on the Hydrogen Economy, S. Linke, ed. (Cornell .University, Ithaca, New York, April 1975), pp. 113-121. 57 PAGENO="0337" 331 22. J. B. Pangborn, "Thermochemical Cracking of Water," in Proceedings of the Cornell International Symposium and Workshop on the Hydrogen Economy, S. Linke, ed. (Cornell University, Ithaca, New York, April 1975), pp. 128-130. 23. H. Barnert, "Thermochemical and Nuclear Technology for Nuclear Water Splitting," in Proceedings of the Cornell International Sym posium and Workshop on the Hydrogen Economy, S. Linke, ed. (Cornell University, Ithaca, New York, April 1975), pp. 130-140. 24. B. M. Abraham and F. Schreiner, "A Low Temperature Thermal Process for the Decomposition of Water," Science, Vol. 180 (1 June 1973), pp. 959-960 and "Low Temperature Thermal Decomposition of Water," Science (28 December 1973), pp. 1372-1373. 25. R. H. Wehtorf, Jr. and R. E. Hanneman, YThermochemical Hydrogen Generation," Science (26 July 1974), pp. 311-319; disputations by R. Shinnar and M. A. Soliman, W. L. Conger, K. E. Cox and R. H. Carty, "Thermochemical Hydrogen Generation Heat Requirements and Cost," Science (6 June 1975), pp. 1036-1037; reply by R. H. Wentorf and R. E. Hanneman, "Thermochemical Hydrogen Generation Heat Re- quirements and Cost," Science (6 June 1975), pp. 1037-1038. 26. J. E. Funk, "Thermodynamics of Thermochemical Hydrogen," in Pro- ceedings of the Cornell International Symposium and Workshop on the Hydrogen Economy, S. Linke, ed. (Cornell University, Ithaca, New York, April 1975), Pp. 122-127. 27. J. E. Funk et al., "Evaluation of Multi-step Thermchemical Processes for the Production of Hydrogen from Water," in Hydrogen Energy, T. N. Veziroglu, ed. (Plenum Press, New York, 1975), pp. 457-470. 28. G. DeBeni, "Considerations on Iron-chlorine-oxygen Reactions in Relation to Thermochemical Water-Splitting," in Hydrogen Energy, T. N. Veziroglu, ed. (Plenum Press, New York, 1975), pp. 471-482. 29. J. B. Pangborn and J. C. Sharer, "Analysis of Thermochemical Water- Splitting Cycles," in Hydrogen Energy, T. N. Veziroglu, ed. (Plenum Press, New York, 1975), pp. 499-516. 30. J. L. Russell and J. T. Porter, "A Search for Thermochemical Water- Splitting Cycles," in Hydrogen Energy, T. N. Veziroglu, ed. (Plenum Press, New York, 1975), pp. 517-532. 58 62-332 0 - 76 * 22 PAGENO="0338" 332 31. R. G. Hickman et al., "Thermochemical Hydrogen Production Research at Lawrence Livermore Laboratory," in Hydrogen Energy, T. N. Veziroglu, ed. (Plenum Press, New York, 1975), pp. 483-498. 32. J. B. Pangborn and D. P. Gregory, "Nuclear Energy Requirements for Hydrogen Production From Water," 9th Intersociety Energy Conversion Engineering Conference, 1974, pp. 400-405. 33. H. Barnert and R. Schulten, "Nuclear Water-Splitting and High Tem- perature Reactors," in Hydrogen Energy, T. N. Veziroglu, ed. (Plenum Press, New York, 1975), pp. 115-128. 34. R. N. Quade and A. T. McMain, "Hydrogen Production with a High Tem- perature Gas-Cooled Reactor (HTGR)," in Hydrogen Energy, T. N. Veziroglu, ed. (Plenum Press, New York, 1975), pp. 137-154. 35. A. F. Hildebrandt and L. L. Vant-Hull, "A Tower-Top Point Focus Solar Energy Collector," in Hydrogen Energy, T. N. Veziroglu, ed. (Plenum Press, New York, 1975), pp. 35-44. 36. W. D. Metz, "Future of Private Laser Fusion Research in Doubt," Science (28 March 1975), p. 1178. 37. E. E. Hughes et al., "Control of Environmental Impacts from Advanced Energy Sources," Environmental Protection Agency Report EPA 600/2- 74-002 (March 1974). 59 PAGENO="0339" 333 CHAPTER 5--STORAGE OF HYDROGEN A. Introduction Hydrogen must be stored to facilitate its distribution to end use consumers and to provide an inventory to buffer variations in supply and demand. Gaseous storage in tanks appears likely to remain impracti- cal except on a very small scale because high pressures are required and this necessitates the use of very heavy and robust tanks. However, there are other candidate storage mechanisms for gaseous hydrogen. Although hydrogen has the second lowest normal boiling point of any substance, o o 0 *. 20.4 K (-253 C or -423 F), it can also be stored as a cryogenic liquid. In addition, hydrogen can be stored in the form of metal hydrides, or by chemical combination to form other compounds. There is no single sto- rage mechanism that would be best for all forms of hydrogen. B. Storage of Gaseous Hydrogen 1. Underground Storage Gaseous hydrogen can be stored underground in three ways:1 * In man-made or natural caverns * In depleted natural gas fields * In suitable aquifers under an impervious rock cap. Worldwide, all of these means to store gases containing hydrogen have been tried to some extent and, while many technical uncertainties remain, all *Absolute zero is 0 K (or equivalently -273°C, -460°F). Only helium has a lower normal boiling point at 4.2°K. 60 PAGENO="0340" 334 will probably be used when the geologic and economic conditions are favorable. A major difficulty in the use of underground caverns is the need to seal all openings so that the pressurized hydrogen gas cannot escape. In relatively nonporous geologic formations, most of the gas entered into storage can later be withdrawn and recovered.1 This easy and nearly total recovery is not just an important economic advantage, it is also an advantage affecting the rate of injection and withdrawal.1 Hydrogen gas can also be pumped underground into depleted na- tural gas fields to occupy the space formerly occupied by the natural gas.1 Such a storage approach is limited by the relatively small void volume available per unit volume of rock (the porosity) and the need for the gas to migrate through the small passages interconnecting the tiny voids (the permeability). Thus, the resulting slow injection and withdrawal rates necessarily limit the application of this form of sto- rage to situations that do not require rapid charge or withdrawal.1 Although hydrogen is known for its ability to leak readily, the rate of loss of "town gas" (largely hydrogen) from a storage facility of this type in France has apparently been quite acceptable.' Helium, another very diffusive gas, long stored in depleted natural gas fields in the southwestern United States as part of a resource conservation effort for a number of years2'~ and thereby provides related technological experience for this form of storage. One drawback to this kind of storage is the requirement that a certain amount of hydrogen must be irretrievably invested in initially charging the field because by no means can all the hydrogen injected later be withdrawn.1 Another drawback affects quality control. Hydro- gen withdrawal flushes out some of the residual natural gas in the field and thus the hydrogen withdrawn is no longer pure; instead, the 61 PAGENO="0341" 335 composition of the withdrawn gas is variable.1 For some end uses, how- ever, such as combustion, this contamination presents few problems; but when hydrogen is used as a chemical, the contamination is at best a nuisance. In some locations, porous rock aquifers are overlaid by nearly impervious cap rock, which is saturated by water forming an effective gas seal. Hydrogen can be stored in the aquifer beneath this lid of rock and water.1 Charging the aquifers with hydrogen displaces some of the water, but a layer of trapped water remains at the top of the aquifer. The seal that retains the hydrogen reportedly comes nearly entirely from the surface tension of the water in the cap rock.1 For this reason, leakage is not a function of the molecular size of the stored gas and this makes this form of hydrogen storage potentially practical. Because of the large scale implied, underground gaseous hydro- gen storage methods are probably more attractive to the utility industry than to other end use sectors. In particular, electric utilities could use these approaches to the storage of hydrogen in load-leveling systems and gas utilities could store hydrogen for seasonal load leveling. 2. Pipeline Storage Hydrogen gas can be stored in transmission pipelines whenever the maximum flow through the pipe is not being fully exploited.1 In this "linepack" technique, the pipeline design pressure is maintained but injections and withdrawals (and hence, "throughput") fall below the maximum possible. For very short term storage, the pipeline may even be allowed to exceed normal operating pressure. The amount of storage that can be realized by the linepack technique depends heavily and in a com- plex way on the total system volume, pressure ratings, and other attri- butes of the actual system.' In early stages of hydrogen economy imple- mentation, when demand would fall somewhat below that which could be 62 PAGENO="0342" 336 supplied by the first pipelines, linepack night prove a useful interim storage method. C. Storage of Liquid Hydrogen Because liquid hydrogen is a very low temperature liquid with prop- erties rarely if ever encountered by the common man, it cannot be stored as casually as water or most familiar fuels.47 At the normal boiling point of hydrogen, many materials in contact with it become brittle and contract from their dimensions at room temperature. Obviously liquid hydrogen containment vessels must be designed differently than the usual simple envelope that is sufficient to contain familiar fuels such as gasoline. The vessel must be very well insulated against the stray in- trusion of heat--even that received in the form of radiation from sur- rounding objects at room temperature. Over the years, experimental laboratories, especially those concerned with cryogenic physical chem- istry and solid-state physics, have accumulated considerable experience in the containment of liquid helium, the element with the lowest normal boiling point (4°.2 K) and liquid nitrogen (77°K). Thus, bracketed in *temperature by liquid helium and liquid nitrogen, understanding of liq- uid hydrogen containment has benefited. Moreover, large research ef- forts to understand liquid hydrogen have been undertaken as part of the U.S. space program. Small quantities of cryogenic liquids are normally stored in a double-walled vessel with vacuum between the two walls (dewar).* Dewars are identical in principle to the glass "thermos" bottle familiar to *At 4.2°K and 2O.4°K any residual trapped gas (such as air) freezes out, thereby improving the degree of vacuum initially established at room temperature. 63 PAGENO="0343" 337 most households. Because the amount of spurious heat that can leak into a dewar is related to its surface area, the larger the ratio of volume to surface area, the slower the rate of boil-off loss. Some boil off is inevitable, however, and, because the ratio of gas volume to liquid volume at 20°K is about 50 to 1, the storage vessel must be able to withstand a pressure buildup between withdrawals of liquid and also equipped with a gas venting device. Some vessels in use today can be safely sealed without venting for weeks at a time. Because of the storage efficiency gained in large containers with a small surface-to-volume ratio (see Table 5-1), it has been possible to greatly simplify the construction principles of large tanks without encountering unacceptable boil-off losses. In the U.S. space program, which uses liquid hydrogen as a rocket propellant, tanks as large as 900,000 gallons have been constructed.4 In these tanks the double walls are separated by "perlite" insulation about a foot thick and evacuated.4'6 As Table 5-1 shows, boil-off rates for tanks this large are as low as 0.03 percent per day. Storage tanks are not allowed to warm appreciably above 20°K be- cause above that temperature there is a large amount of boil-off when liquid hydrogen is reintroduced into the warm tank again chilling it down to liquid hydrogen temperature. Thus, unless a tank is in need of repair, some hydrogen is routinely left in the tank to maintain a low temperature. Flexible, vacuum-insulated, transfer tubes are used during an addition or withdrawal transfer operation to a storage vessel. Tanks are maintained at a pressure slightly above ambient to prevent outside air from infiltrating the tank because air immediately freezes into a solid composed of oxygen, nitrogen, and ice, and this clogs passages or forms an undesirable residue in the tank bottom. Moreover, because air taken from room temperature down to cryogenic temperatures contracts by 64 PAGENO="0344" 338 Table 5-1 STORAGE EFFICIENCY OF LIQUID HYDROGEN CONTAINERS Capacity Boil Off (gallons) Class of Use (% per day) Reference 900,000 Stationary 0.03 4 500,000 Stationary 0.05 4 28,000 Railcar delivery 0.3 8 13,000 Truck delivery 0.5 8 260 Mobile 1.0 9 40 Mobile 2.0 9 a factor of about 700, a small inward leak can "cryopump" large quanti- ties of air into the storage tank. A well-designed and correctly main- tained transfer system surmounts this problem, but technical refinements necessary for storage and transfer pose barriers to the casual use of liquid hydrogen by untrained personnel. At present, small liquid hydrogen storage vessels are expensive and this poses an obstacle to the use of liquid hydrogen in modest quan- ties--such as in automobiles. However, new design concepts, materials, and fabrication techniques are beginning to emerge that very likely will improve this situation immensely. Aluminum tanks enclosed in rigid, closed cell plastic foam are an example of the promising new directions. D. Liquefaction for Storage Liquefaction of hydrogen is a complicated exercise in cryogenic engineering.l0~hl Today, worldwide, there are very few commercial scale liquid hydrogen plants, and the bulk of the output still goes to the 65 PAGENO="0345" 339 U.S. space program. The Linde Division of Union Carbide Corporation has been the most active producer of cryogenic liquids that has con- tributed to the hydrogen energy economy concept. Linde plants obtain their hydrogen from the reformation of methane (natural gas).'2 To liquify hydrogen, energy must be withdrawn from the gas to con- dense it.1° Since there is only one other cryogenic liquid with a lower boiling point, it is not a simple matter to cool the hydrogen and, hence, the process is complicated and depends heavily on the proper operation of efficient heat transfer devices at cryogenic temperatures.12 Before liquefaction begins, and during the process, the hydrogen must be kept very pure because every contaminant except helium (an unlikely contami- nant) will condense and freeze in the process and heat-transfer piping, which would clog the piping and also render less efficient the heat transfer surfaces.12 Linde reportedly achieves less than 1 ppm total impurity before liquefaction begins.12* Scant improvement is expected in the energy efficiency of liquefaction because it is now being achieved at about 40 percent of the theoretical (but never attainable) `ideal" efficiency.11 For cryogenic liquids, this is good performance. The efficiency of liquefaction (using current technology) is about 77 per- cent if efficiency is defined as the energy contained in the heat of combustion of the liquid hydrogen divided by the sum of the heat of com- bustion of the gaseous starting hydrogen and the electrical energy needed to achieve liquefaction.~~ This efficiency figure includes the *As result of this purity, industries that need very pure gaseous hydro- gen for chemical uses (e.g., the semiconductor industry) purchase liq- uid hydrogen and then gasify it to obtain their hydrogen chemical reagent. This use of hydrogen, while important for what it achieves, currently consumes only a small portion of total liquid hydrogen production. 66 PAGENO="0346" 340 effort required in a physical phase transition unique to hydrogen--the "ortho-to-para" conversion.13* Efficient liquefaction is almost cer- tainly limited to large-scale plants, although less efficient liquefac- tion might be tolerated for small-scale uses. Small (e.g., 150 liters! day) liquefaction units that are not very energy efficient are commer- cially available today. Liquid hydrogen is shipped from commercial liquefaction plants in large dewars mounted on semitrailer trucks (capacity about 13,000 gal- lons) or on railroad cars (capacity about 28,000 gallons). The trucks are used for deliveries within about a 1000-mile range and the rail cars are sometimes used to deliver hydrogen across the continent.12 The boil-off rates of these mobile storage containers is sufficiently low (see Table 5-1) that hydrogen gas is not vented en route but rather is allowed to build up pressure in the tank.12 Such pressurization is use- ful because it provides a driving force for hydrogen withdrawal although in practice the vaporized hydrogen is subsequently lost. E. Storage in the Form of Metal Hydrides Surprisingly, as shown in Table 5-2, more hydrogen atoms can be packed into some metal hydrides than into the same volume of liquid *The hydrogen molecule can exist in either of two molecular "spin" states called ortho and para. Both states are present when hydrogen is liquified (75 percent ortho and 25 percent para). In the liquid state the para spin state is stable but the ortho is not. Left alone, the hydrogen would gradually convert almost entirely to the para state. This transition, however, releases enough energy to cause substantial boil-off of the hydrogen. Thus, unless this physical transition is driven to completion artificially with the heat released removed by refrigeration, the hydrogen would boil off during storage as the na- tural ortho-to-para conversion proceeded. A catalyst is used in this conversion. 67 PAGENO="0347" 341 hydrogen.14 Not all metal hydrides pack hydrogen so effectively, but many do (e.g., magnesium hydride and iron titanium hydride). Table 5-2 HYDROGEN DENSITY OF VARIOUS SUBSTANCES Density Substance (grams/cm3) ~ (liquid hydrogen) 0.07 NH3 (ammonia) 0.6 LiH 0.8 MgH3 1.4 TiH2 3.8 Storage in a metal hydride is a physical/chemical process involving the diffusion of hydrogen atoms through the crystal structure of a solid metal or alloy where they react to form chemical compounds.'~ As shown schematically in Figure 5-1, the hydrogen atoms take up residence be- tween the atoms comprising the crystal of the host material. Specific metal hydrides absorb only well-defined maximum amounts of hydrogen; accordingly, the metal hydride formula (e.g., MgH2, LaNi5H6, FeTiH2) is written in a manner that represents the maximum hydrogen concentrations attainable. Because the rate of formation and decomposition of a metal hydride depends on the rate that hydrogen can diffuse from the outer surface of the metal inward to a vacant site in the crystal structure, pieces of metal with a surface-to-volume ratio as large as possible are used in 68 PAGENO="0348" 342 HOST METAL ATOMS * HYD~OGEP4 ATOMS FIGURE 5-I. INTERSTITIAL SITES FOR HYDROGEN IN A CRYSTAL LATTICE applications of hydrides. Normally small metal granules or a metal powder are used as the host. The formation of most metal hydrides is exothermic;1~"6 that is, heat is released as the conversion from metal to metal hydride proceeds. Consequently, during the formation process, heat must be removed from the "bed" of particles by heat transfer devices embedded in it.14 To release gaseous hydrogen it is necessary to reverse the process of hy- dride formation, which means that same quantity of heat withdrawn during formation of the hydride must be added to it. The rates at which hy- drides form or decompose are unique to each hydride substance. Curves showing the amount of hydrogen absorbed at different temperatures and pressures in FeTiH and Mg2NiH2, two of the hydrides thought to be most useful in practical devices, are shown in Figures 5-2 and 5-3. Since metal hydrides are exothermic on formation and endothermic on decomposition, many have suggested that if a metal hydride were used 69 PAGENO="0349" 0 COMPOSITION, H/(Mg+ Ni) FIGURE 5-2. PRESSURE-COMPOSITION ISOTHERMS FOR THE Mg2NI-H METAL HYDRIDE SYSTEM PAGENO="0350" 344 as the fuel tank of an automobile, the waste heat of the engine rejected in its exhaust could be used to extract the hydrogen.'7'9 This would utilize energy normally wasted into the atmosphere. Conversely, on hydride formation, the same amount of energy is released, and it might be possible to collect it and put it to a beneficial use.19 Thus, in effect, some of the waste energy from hydride-equipped vehicles might be conserved and put to use. This last concept of energy collection is probably not really viable, however, if the depleted fuel tank is re- charged at hundreds of thousands of individual service stations. Metal hydrides offer several potential advantages over the storage of hydrogen in liquid form. First, because the hydrogen is handled in gaseous form, the energy expenditure associated with liquefaction is saved. Second, while a leak in a liquid hydrogen tank results in a spill and immediate evaporation and dissipation of the hydrogen (per- haps with danger to people (see Chapter 8), a rupture in the vessel con- taining the metal hydride particles would not result in the release of hydrogen unless heat were applied; this offers safety against unwanted fuel combustion. Third, as already noted, the packing density of the hydrogen atoms can be higher than in the liquid. There are also some drawbacks to the use of metal hydrides. First, impurities in the hydrogen gas, especially sulphur and oxygen, poison the hydride bed, thereby interfering with the hydride formation. This phenomenon is not now understood.16 Second, metal hydrides are brittle materials and repeated charge-discharge storage cycles tend to fracture the metal particles. As they become ever smaller, the particles tend to settle, pack, and cake. This slows the passage of hydrogen gas among the particles and thus reduces the reaction rates (in spite of the in- creased net surface to volume ratio). Third, metal hydrides are far heavier than liquid hydrogen (even one of the lightest, MgI!2 is about 13 times heavier for the same quantity of hydrogen stored). This makes 71 PAGENO="0351" 345 the use of metal hydrides more unwieldy for mobile storage than for stationary storage. Considerable research is now under way, especially at Brookhaven National Laboratory, to further characterize the properties of candidate metal hydride compounds and to demonstrate storage systems on a practi- cal scale. F. Storage in Chemical Compounds There are many other chemical compounds in which hydrogen can be stored and transported. These compounds can then be consumed directly or first decomposed to yield the hydrogen. Candidate compounds include ammonia, NH3 hydrazine, N2H4, boranes, silanes, and synthetic carbons containing compounds such as alcohols. Of these, ammonia is possibly the most interesting because the only other element required, nitrogen, is the major constituent (80 percent) of air. Some people would therefore include these compounds as part of the hydrogen energy economy concept. Indeed, at hydrogen energy symposia, papers on methanol (methyl alcohol) and ammonia are sometimes presented. However, to limit the scope of this study we have excluded these chemi- cal compounds from consideration, because, in our opinion, the main thrust of hydrogen energy concept begins to fade substantially in these * cases. *We recognize, however, that the inclusion of metal hydrides and the ex- clusion of ammonia--which can be viewed as a nitrogen hydride--is some- what arbitrary. 72 PAGENO="0352" 346 REFERENCES 1. D. P. Gregory et al., "A Hydrogen-Energy System," American Gas Association, Alexandria, Virginia (August 1972). 2. W. D. Metz, "Helium Conservation Program: Casting It To the Winds," Science (11 January 1974), PP. 59-63. 3. C. A. Price, "The Helium Conservation Program of the Department of the Interior," in Patient Earth, J. Harte and R. H. Socolow, eds. (Holt, Rinehart and Winston, New York, 1971). 4. J. R. Bartlit, F. J. Edeskuty, K. D. Williamson, Jr., "Experience in Handling Transport, and Storage of Liquid Hydrogen--the Recyclable Fuel," 7th Intersociety Energy Conversion Engineering Conference, 1972, pp. 1312-1315. 5. F. A. Martin, "The Safe Distribution and Handling of Hydrogen for Commercial Application," 7th Intersociety Energy Conversion Engi- neering Conference, 1972, pp. 1335-1341. 6. F. J. Edeskuty and K. D. Williamson, Jr., "Storage and Handling of Cryogens," in Advances in Cryogenic Engineering, 17, K. D. Timmer- haus, ed. (Plenum Press, New York, 1972). 7. 3. R. Bartlit, "Liquid Hydrogen Handling, Transport and Storage," in Proceedings of the Cornell International Symposium a~id Workshop on the Hydrogen Economy, S. Linke, ed. (Cornell University, Ithaca, New York, April 1975), pp. 95-101. 8. Mr. John E. Johnson, Linde Division, Union Carbide Corporation, New York, New York (personal communication). 9. L. W. Jones, "Liquid Hydrogen as a Fuel for Motor Vehicles: A Comparison with Other Systems," 7th Intersociety Energy Conversion Engineering Conference, 1972, pp. 1364-1365. 10. R. F. Barron, "Liquefaction Cycles for Cryogens," in Advances in Cryogenic Engineering, 17, K. D. Timmerhaus, ed. (Plenum Press, New York, 1972), pp. 20-36. 73 PAGENO="0353" 347 11. W. R. Parrish and R. 0. Voth, "Cost and Availability of Hydrogen," in Selected Topics on Hydrogen Fuel," J. Hord, ed., Report NIBS IR 75-803, Cryogenics Division, National Bureau of Standards, Boulder, Colorado (January 1975). 12. Mr. T. J. Lewanski, Linde Division, Union Carbide Corporation, Fontana, California (personal communication). 13. L. T. Blank et al., "A Hydrogen Energy Carrier," Systems Design Institute, National Aeronautics and Space Administration-American Society for Engineering Education, Johnson Space Center, Houston, Texas (1973). 14. R. D. Wiswall, "Hydrogen Storage Via Hydrides," in Proceedings of the Cornell International Symposium and Workshop on the Hydrogen Economy, S. Linke, ed. (Cornell University, Ithaca, New York, April 1975), pp. 102-109. 15. Dr. Richard Wiswall of Brookhaven National Laboratory, Upton, Long Island, New York (personal communication). 16. R. H. Wiswall and J. J. Reilly, "Metal Hydrides for Energy Storage," 7th Intersociety Energy Conversion Engineering Conference, 1972, pp. 1342-1348. 17. R. E. Billings, "Hydrogen Storage in Automobiles Using Cryogenics and Metal Hydrides," in Hydrogen Energy, T. N. Veziroglu, ed. (Plenum Press, New York, 1975), pp. 791-801. 18. C. H. Waide, J. J. Reilly, R. H. Wiswall, "The Application of Metal Hydrides to Ground Transportation," in Hydrogen Energy, T. N. Veziroglu, ed. (Plenum Press, New York, 1975), pp. 779-790. 19. A. L. Austin, "A Survey of Hydrogen's Potential As a Vehicular Fuel," University of California Radiation Laboratory - 51228, Livermore, California. 74 62-332 0 - 76 - 23 PAGENO="0354" 348 CHAPTER 6--DISTRIBUTION OF HYDROGEN A. Distribution in Gaseous Forms Gaseous hydrogen has long been distributed in small quantities at high pressure (2000 psi) in robust steel cylinders. However, because the most commonly sized cylinders are very heavy (about 160 lbs) and contain very little hydrogen (only about 240 SCF or 1.3 lbs), this form of distribution is impractical for major use in a hydrogen energy economy. By far the most practical* form of large-volume hydrogen distribu- tion is through pipelines in a manner akin to the present distribution of natural gas.1'2 Natural gas and hydrogen, however, are different in physical properties and affect materials differently.28 Consequently, considerable attention must be given to the details of pipeline trans- mission. The natural gas industry, anticipating a worsening shortage of methane, has shown considerable interest in the distribution of gas- eous hydrogen because it is the logical alternative to methane for use in homes, industry, and commerce.t The volumetric heating value of hydrogen is only about one-third that of methane; thus, for the same volumetric flow, a pipeline could deliver only about one-third as much *Although it is probably more romantic than practical, large-volume dis- tribution in balloons and blimps might be useful to deliver relatively small amounts to remote locations distant from highways or railways where demand could not justify a pipeline. ~Accordingly, the American Gas Association has funded considerable study of hydrogen for utilities--most of it performed at the Institute of Gas Technology (IGT). 75 PAGENO="0355" 349 energy in the form of hydrogen as it could in the form of methane. How- ever, this disadvantage of hydrogen is offset by its lower density and viscosity (i.e., it flows through the pipe with less frictional drag than does methane). On this premise, it was thought that nearly the same amount of energy might be transmitted feasibly either as methane or hydrogen.~-'2'9'2 Until 1974, therefore, when the first hydrogen pipeline optimizations were made, 13-16 it was commonly believed that existing natural gas transmission pipelines could be converted to hydro- gen use merely by the installation of more closely-spaced and higher capacity compression stations. However, recent optimization studies have shown that a pipeline optimized to transmit hydrogen would deliver only about 0.6 to 0.7 times14'16 as much energy as the same pipeline operating at the same pressure but optimized for natural gas, and hence larger diameter pipe- lines are implied. Cost studies have indicated that hydrogen pipelines should be operated at pressures conventionally used in natural gas pipe- lines (750 psi) or higher. If the hydrogen gas is produced at low pres- sure and must therefore be greatly compressed for use in the pipeline, large energy and cost penalties must be paid.'6 Although this finding somewhat diminishes the attractiveness of a conversion from methane to hydrogen, there are other more serious drawbacks. The problem of hydrogen embrittlement of metals ranks first among the other drawbacks. There are two important classes of hydrogen em- brittlement of metal:7'8 * Internal hydrogen reactions (e.g., hydrogen combining chemically with the carbon in steel to form microscopi6 bubbles of methane, CH4). * "Environment' embrittlement. However, in transmission pipelines only hydrogen environment embrittle- ment causes great concern6~7~8 --primarily for reasons of system integrity 76 PAGENO="0356" 350 and safety. The hydrogen environment embrittlement phenomenon is most pronounced at high pressures, high purity hydrogen, and near room7'8 temperatures. The effect is manifested as the formation and propagation of cracks through a stressed metal or alloy until fracture occurs.38 In effect, a normally ductile metal becomes brittle. This kind of em- brittlement initiates essentially instantaneously (in less than a sec- ond) when the hydrogen and metal are exposed to each other; the effect ceases just as rapidly when the metal is removed from the hydrogen en- vironment.7 Although the onset of the effect is instantaneous, failure is not. Removal of the metal from the hydrogen environment does not remove the cracks; it merely removes the susceptibility. Although the actual physical mechanisms involved are not well understood, the occur- rence of the phenomenon is well documented.~8 Small amounts of some impurities in the hydrogen, notably oxygen, suppress embrittlement.7 The intensity of the effect varies greatly from metal to metal, but high strength steel alloys are most susceptible, as are ordinary carbon steels.8 There is hope that hydrogen environment embrittlement can be controlled by the use of protective plating with a less susceptible metal or through the introduction of controlled impu- rities.7 Because hydrogen diffuses readily through plastics, insertion of a plastic liner or application of a plastic coating would not prevent embrittlement. * Metallurgists and engineers expect that a better understanding of hydrogen environment embrittlement can facilitate workable design and materials selection guidelines and fabrication codes that would guarantee *A major chemical company is rumored to have developed a plastic imper- vious to hydrogen; to our knowledge, however, this rumor has not been verified by a product announcement. 77 PAGENO="0357" 351 sufficient compensatory strength. However, to the extent that more sophisticated configurations or materials were required such design would probably consume more material and labor and thus result in in- creased fabrication costs. It is possible that the hydrogen normally transmitted would not be pure enough to cause embrittlement; thus, in practical application hydrogen environment embrittlement may be much less a problem than laboratory experiments suggest. A pipeline about 130 miles long has been distributing hydrogen in Germany for nearly 30 years with no apparent problems of hydrogen en- vironment embrittlement.17'9 This example is frequently cited in lit- erature on the hydrogen economy as a counter to suggestions that em- brittlement is a serious problem. Unfortunately, the example is not fully apt. In the first place, the purity of the hydrogen always re- mains unspecified, and the pressures involved are only about 360 psi17 compared with the 750 to 1000 psi contemplated for hydrogen trunk pipe- lines.15 Thus, while this experience serves as a valuable lesson, it is only a starting point for the analysis that must precede use of a pipeline to transmit hydrogen. The tendency of hydrogen to leak from pipelines is another drawback. Since hydrogen diffuses through smaller holes than methane, a pipeline that had been "tight' for methane could prove "leaky" for hydrogen.2 Old and leaky local methane distribution pipelines have sometimes been rejuvenated by the insertion of a plastic inner sleeve; the easy diffu- sion of hydrogen through plastic would render these rejuvenated pipelines obsolete once again. Local methane distribution pipelines are surpris- ingly leaky (typically between 100,000 and 400,000 SCF leakage per mile per year),2 and the leakage rate of hydrogen would be even higher. The higher volumetric leakage would be offset, however, by the lower rela- tive heating value of hydrogen compared with methane. Thus on an energy basis leakage rate might not be more severe than is presently accepted 78 PAGENO="0358" 352 for methane.2 (Safety aspects of hydrogen leaks are discussed in Chapter 8.) It is frequently asserted that the conversion of methane transmis- sion pipelines to hydrogen would save this large capital investment from obsolescence. However, a number of considerations cast doubt on this argument. Figure 6-1 shows that the trunk natural gas pipeline network fans out from the major natural gas producing areas largely concentrated in the Gulf Coast region. These either terminate or taper in capacity with increasing distance from the gas fields as consumption lowers the quantity left to transmit. There is no natural reason to concentrate major hydrogen producing facilities in the Gulf Coast region--least of all hydrogen from coal gasification, a likely first source of hydrogen. Thus, because the existing trunk pipelines generally do not link the correct places and taper in the inappropriate direction, the argument that conversion to hydrogen would protect those investments seems to be overstated. At best, it appears that only some trunk pipelines would remain useful. FIGURE 6-i NATURAL GAS TRANSMISSION PIPELINES IN THE UNITED STATES. 79 PAGENO="0359" 353 Because, on a volume basis, the heating value of hydrogen is only about one-third that of methane, nearly three times as much hydrogen is needed to deliver the same energy. Most of the present gas metering systems, especially at the level of the dwelling unit, could not cope with this added f low.2 Consequently, most meters would have to be al- tered or replaced--at considerable trouble and expense. Although at first sight it might be presumed that a switch to hy- drogen could preserve intact the investment in the present natural gas distribution system, matters are not that simple in reality. B. Distribution in Liquid Form The physical properties and handling characteristics of liquid hy- drogen are discussed in Chapters 4, 5, and 8. Today, most liquid hydro- gen is consumed by the U.S. space exploration program. Liquid hydrogen is routinely transported by special railroad tank cars and highway trucks to vehicle launch sites, as well as to sites of space R&D, pro- duction, and testing.2°'21 The volumes distributed by rail car and highway truck* are limited by legal size restrictions, but the weight limits have not been reached because of hydrogen's extremely low density.21 It is technically possible to distribute liquid hydrogen through an extremely well insulated cryogenic pipeline. However, the costs of such a pipeline are very high;23t such pipelines are economically *A representative of the Linde Division of Union Carbide Corporation re- ports that truck drivers that load and convey the liquid hydrogen re- ceive abouf three day's special instruction but are not otherwise unusual in education or background.22 tAbout $100 per linear foot (or more than $500,000 per mile) for a pipe 5 inches in diameter.23 80 PAGENO="0360" 354 practical for only very short distances and very high hydrogen flow rates. Consequently, in the early implementation of any aspect of a hydrogen energy econony requiring liquid hydrogen, delivery in batches by truck or train is most likely. Indeed, even for hydrogen shipments to Cape Canaveral for space launches, batch delivery was (and is) em- ployed.24 In the future, it generally would prove most economical to transport gaseous hydrogen by pipeline from its point of production to its point of liquefaction and then to distribute the liquid by truck or train. The sole exception may be in the commercial aviation sector. Near an airport it might prove advantageous (and even necessary for public safety reasons) to move liquid hydrogen underground a mile or so from the liquefaction plant or storage areas to the aircraft fueling stations. The high cost of such pipelines would be a strong incentive for adoption of a single central refueling terminal (as at Dulles Air- port serving Washington, D.C.) instead of refueling at each departure gate as is now done for kerosene type jet fuels. C. Distribution in Metal Hydride Form Although it would be possible to distribute "charged" metal hydride beds and return "empty" beds to and from a central recharging point, the metal bed is heavy compared with the weight (and hence energy) of the hydrogen contained. Thus, in general, for reasons of weight, metal hydride beds cannot be expected to be used as a form of hydrogen dis- tribution. Instead, when hydrides are used for hydrogen storage the hydrogen will be conveyed to the bed by pipeline. However, in the automotive sector, metal hydrides might possibly be moved short distances to the user (although this would be limited by their heavy weight). For example, a depleted hydride bed from the car might be physically exchanged for a charged bed at the filling station. At the filling station, purified hydrogen could be used to 81 PAGENO="0361" 355 recharge the bed, but it might turn out that economies of scale in hydrogen purification and hydride recharge would require a large re- gional hydride recharge center. In that event, hydride beds might be transported small distances between the center and filling stations, but this would probably prove too expensive to be viable. D. Summary Most likely the most economical and convenient future way to dis- tribute vast quantities of hydrogen will be by gas pipeline. When needed, liquefaction could then be accomplished near the end use, and most metal hydrides would be charged in place rather than transported. Even distribution by pipeline has a major economic hurdle to overcome: unless the hydrogen is produced at high pressure directly, the cost of pumping the hydrogen up to pipeline pressure will be high.16 This will pose a large barrier to the implementation of nearly all facets of the hydrogen energy economy concept. Another approach to the use of metal hydrides in automobiles is to have a bed permanently located in the car that is charged by gas deliv- ered by pipeline either to the home* or to a "filling station." *High purity hydrogen is important to the proper functioning and long- evity of the hydride bed. Because the hydrogen obtained in the home from a common pipeline is unlikely to be reliably pure, we question the realism of this approach. 82 PAGENO="0362" 356 REFERENCES 1. D. P. Gregory, "The Hydrogen Economy," Scientific American (Janu- ary 1973), pp. 13-21. 2. D. P. Gregory et al., "A Hydrogen-Energy System," American Gas Association, Alexandria, Virginia (August 1972). 3. R. P. Jewett et al., "Hydrogen Environment Embrittlement of Metals," National Aeronautics and Space Administration Report CR-2l63 (March 1973). 4. H. H. Johnson and A. J. Kumnick, "Hydrogen and the Integrity of Structural Alloys," in Hydrogen Energy, T. N. Veziroglu, ed. (Plenum Press, New York, 1975), pp. 1043-1055. 5. A. W. Thompson, "Structural Materials Use in a Hydrogen Economy," paper 37c, presented at the Annual Meeting, American Institute of Chemical Engineers, Washington, D.C., 3 December 1974. 6. H. H. Johnson, "Hydrogen Embrittlement," Science, Vol. 179 (19 Jan- uary 1973), p. 228. 7. W. T. Chandler and R. J. Walter, "Hydrogen Environment Embrittlement of Metals and Its Control," in Hydrogen Energy, T. N. Veziroglu, ed. (Plenum Press, New York, 1975), pp. 1057-1078. 8. A. J. Kumnick, "Hydrogen Embrittlement," in Proceedings of the Cornell International Symposium and Workshop on the Hydrogen Economy, S. Linke, ed. (Cornell University, Ithaca, New York, April 1975), pp. 422-423. 9. D. P. Gregory, "A New Concept in Energy Transmission," Public Utilities Fortnightly (3 February 1972), pp. 3-11. 10. D. P. Gregory and J. Wurm, "Production and Distribution of Hydrogen as a Universal Fuel," 7th Intersociety Energy Conversion Engineer- ing Conference, 1972, p. 1329. 83 PAGENO="0363" 357 11. "Hydrogen and Other Synthetic Fuels," a summary of the work of the Synthetic Fuels Panel, prepared for the Federal Council on Science and Technology R&D Goals Study (September 1972). 12. L. T. Blank et al., "A Hydrogen Energy Carrier," Systems Design Institute, National Aeronautics and Space Administration-American Society for Engineering Education, Johnson Space Center, Houston, Texas (1973). 13. G. Beghi et al,, "Economics of Pipeline Transport for Hydrogen and Oxygen," in Hydrogen Energy, T. N. Veziroglu, ed. (Plenum Press, New York, 1975), pp. 545-560. 14. R. A. Reynolds and W. L. Slager, "Pipeline Transmission of Hydrogen," in Hydrogen Energy, T. N. Veziroglu, ed. (Plenum Press, New York, 1975), pp. 533-543. 15. A. Konopka and J. Wurm, "Transmission of Gaseous Hydrogen," 9th Intersociety Energy Conversion Engineering Conference, 1974, pp. 405-412. 16. D. P. Gregory, "The Hydrogen Economy in Perspective," in Proceedings of the Cornell International Symposium and Workshop on the Hydrogen Economy, S. Linke, ed. (Cornell University, Ithaca, New York, April 1975), pp. 17-26. 17. C. Isting, "Experience with a Hydrogen Pipeline Network," Chemische Werke Bills AG, Marl, Federal Republic of Germany (undated). 18. C. Harchetti, "Hydrogen, Master Key to the Energy Market," Euro- Spectra, Vol. 10, No. 4 (December 1971), pp. 117-129. 19. D. P. Gregory and J. Wurm, "Production and Distribution of Hydrogen as a Universal Fuel," 7th Intersociety Energy Conversion Engineer- ing Conference, 1972, p. 1329. 20. J. R. Bartlit, F. J. Edeskuty, K. D. Williamson, Jr., "Experience in Handling, Transport, and Storage of Liquid Hydrogen--the Re- cyclable Fuel," 7th Intersociety Energy Conversion Engineering Conference, 1972, pp. 1312-1315. 21. F. A. Martin, "The Safe Distribution and Handling of Hydrogen for Commercial Application," 7th Intersociety Energy Conversion Engi- neering Conference, 1972, pp. 1335-1341. 84 PAGENO="0364" 358 22. Mr. John E. Johnson, Linde Division, Union Carbide Corporation, New York, New York (personal communication). 23. J. Hord, "Cryogenic H2 and National Energy Needs," paper N-l pre- sented at the Cryogenic Engineering Conference, Atlanta, Georgia, 8-10 August 1973. 24. C. R. Dyer, H. Z. Sincoff, P. D. Cribbins, eds., "The Energy Dilemma and Its Impact on Air Transportation," National Aeronautics and Space Administration-American Society for Engineering Educa- tion, Langley Research Center, Hampton, Virginia (1973). 85 PAGENO="0365" 359 CHAPTER 7--END USES OF HYDROGEN A. Versatility of Application Hydrogen could be used in nearly every energy application that re- lies on fuel combustion (oxidation). In addition, hydrogen offers oppor- tunities for unconventional energy and chemical technologies--such as fuel cells and flameless catalytic burners. The technological options offered by hydrogen are the subject of this chapter. B. Energy Utilities 1. Gas Utilities Methane, the major component of natural gas, is easily dis- tributed in pipelines and stored in simple tanks and underground in geo- logical strata. Moreover, since it is relatively clean burning and easy to control, it is a most favored fuel with rapidly increasing demand, not only in residences but in commercial establishments and in industry. Unfortunately, as shown in Figures 7-1 and 7-2, reserves of methane have been falling steadily as the soaring demand depletes producing gas fields.1 Meanwhile, price regulation by the Federal Power Commission of natural gas shipped interstate severely reduced the incentive of the gas producer to discover and develop more reserves. Already some demand for natural gas is not being met because domestic production2 is inade- quate. Some methane, including its liquified form, is imported from other nations. The natural gas industry, recognizing that its survival is at stake, is turning to coal gasification to produce a synthetic methane. 86 PAGENO="0366" PROVED RESERVES 180 160 40 35 30 25 2S 15 10 0 10 15 20 0 0 1935 1940 1945 1950 55 SOURCE: PROJECT INDEPENDENCE REPORT REFERENCE 25 -~ 1947 48 49 50 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 SOURCE: PROJECT INDEPENDENCE REPORT, REFERENCE FIGURE 7-I. U.S. NATURAL GAS CONSUMPTION FIGURE 7-2. U.S. NATURAL GAS RESERVES PAGENO="0367" 361 For residences and commercial establishments hydrogen is a potential substitute for natural gas. It could be used in a manner analogous to the use of natural gas for:35 * Space heating by combustion in conventional furnaces. * Space cooling by combustion in absorption-type air conditioners. * Clothes drying appliances. * Stove top and oven cooking. * Hot water heating. Besides such conventional applications, hydrogen piped to residences or to commercial establishments offers the opportunity for some new ap- plications: * Cooking and heating by means of flameless catalytic burners * Generation of electricity with a fuel cell. Flameless catalytic combustion of hydrogen is already a reason- ably well developed technology--temperatures can be varied between mere warmth and temperatures high enough for cooking.3'6 Catalytic burners distributed through a building could be used for space heating much as baseboard electric heaters are used. However, the relative difficulty of deploying leakproof pipe, compared with that of deploying electric cabling, brings the practicality of this concept into question. Indeed, the fuel cell application suggests that if hydrogen were widely dis- tributed to residences, an "all hydrogen home" analogous to an "all- electric home" would be possible, although this would mean that the size of the fuel cell would have to be chosen to meet peak demands. For safe use in residences, it is generally agreed that an "odorant" would have to be added to the odorless hydrogen so that people could smell leaks.3'5'6 The addition of an odorant has long been 88 PAGENO="0368" 362 required for residential use of methane (also odorless) in most states. It is also commonly accepted that for safety a colorant (illuminant) would have to be added to the hydrogen so that hydrogen's normally in- visible flame could be seen.~'5'6 Unfortunately, such odorants and colorants added to hydrogen gas makes the use of the catalytic burners and fuel cells more diff i- cult. Operation of both these devices requires catalysts, which are readily "poisoned" (rendered less effective or useless) by the cheapest (sulfur containing) odorant and colorant chemical compounds.3 However, this drawback will probably be overcome by the development and use of alternative ądorants and colorants or by additional research on and development of alternative catalysts. The combustion of hydrogen requires burners designed for hydrogen. A simple change in fuel with no change in equipment gives unsatisfactory results. Flame propagation, temperature, and other physical combustion properties of hydrogen differ from methane and smaller gas orf ices are required in the burner for hydrogen than for methane. There is no technical barrier, however, to the production and use of hydrogen burners.3'7 Indeed, before natural gas was abundant, "town gas," "water gas," "coal gas," or "manufactured gas" (all mixtures of hydrogen, carbon monoxide, and other substances) were commonly piped to residences.36 Thus, substantial experience concerning the design of burners for hydrogen-rich gases is available.3 Because the primary product of hydrogen combustion is (non- toxic) water vapor, it is often said that hydrogen offers an advantage over methane combustion for space heating because venting would not be necessary to exhaust toxic combustion products (especially carbon mon- oxide). Without venting, a structure could be sealed thereby saving energy normally expended to heat newly infiltrated air. Moreover, in 89 PAGENO="0369" 363 cold winter climates the buildup of humidity (if not carried to extremes) would increase human comfort in the normally dry heated indoor air.3 Unfortunately, this argument overlooks the need for air infiltration to provide the oxygen to support combustion--just as in methane systems. Many methane systems already avoid burning heated air by drawing com- bustion air directly from the outdoors. Consequently, the advantage of hydrogen for space heating is often overstated. Nevertheless by elimi- nating the loss of heat up the flue, hydrogen should yield a net gain in efficiency. Industrial use of hydrogen would go beyond the uses mentioned for residential, commercial applications to combustion for process heat and generation of process steam. These two uses consume about 30 per- cent and 45 percent respectively of all U.S. industrial energy use.9 Currently, natural gas is highly favored by industry because of its artificially low cost and very clean combustion properties (which lower costs of pollution control). However, as the availability of natural gas diminishes, the industrial use of natural gas is being curtailed drastically. Because of the clean combustion properties of hydrogen, indus- tries would find special advantage in its combustion for process heat, Indeed, this clean combustion could warrant a price premium for hydrogen above alternative fuels because the expense of pollution control devices could be largely avoided (some control of N0~might still be needed). Again, use of the correct burner design would be essential. The generation of process steam is probably the most attrac- tive industrial use of hydrogen. When hydrogen is burned with pure oxygen the only combustion product is water vapor (steam).3'9 As a result, it is feasible to generate high quality, high purity steam directly without the use of conventional boilers.9 Clearly, the 90 62-332 0 - 76 - 24 PAGENO="0370" 364 elimination of boilers must be traded off against the added expense of providing pure oxygen either by purchase or production in an air sep- aration unit. There are considerable advantages of producing steam in this manner. First, the steam is produced at a very high temperature--so high, in fact, that water must usually be injected to lower the tempera- tures so that conventional materials can handle the steam.9 Second, the steam is very pure. Third, since not even NO~ is produced and the sole combustion product is the steam, there is no need to provide controls for air pollutants. Unfortunately, however, if industry obtains its supply of hydrogen from the same source as the residential market, the required odorants and colorants add a chemical impurity to the steam.* The odorant and colorant safety additives also affect the po- tentially large industrial use of hydrogen as a chemical reactant. Chemical purification often would be needed to remove the safety addi- tives before hydrogen could be used as a chemical. This impurity re- moval would not necessarily be a burdensome extra cost, however, because industries normally control the purity of incoming chemicals when they are destined to be used for high purity applications. Today it is un- clear what purity hydrogen would be made available at the residential or industrial consumer level because the purity will largely depend on the means of hydrogen production and its storage and distribution en route to the consumer. For many reasons, the gas industry prefers to gasify coal to produce methane rather than hydrogen because synthetic methane can be *It might be feasible, however, to only inject the additives at residen- tial substations, thereby leaving the hydrogen uncontaminated for industry. 91 PAGENO="0371" 365 blended with natural gas supplies with no change being apparent to the customer and no change being required in gas utility local distribution networks. However, because even coal gasification would cease to be a cheap source of methane as increased demand for coal raised its price, a shift to nonfossil hydrogen might still be necessary later. That time is generally beyond the planning horizon of the beleagured gas industry, however. Chapter 16 further discusses gas utility applications. 2. Electric Utilities One of the most vexing problems of electric utilities is the variation in demand at different times of the day, different days of the week, and different months of the year.16'1°1~ Sample load factor curves are shown in Figure 7-3. Yet, because for any given utility these variations in "load-factor" are fairly predictable, utilities have gen- erally found the means to cope with the variations. However, these vari- ations in demand necessitate investment in generating equipment sized to meet peak demand. This means that much generating capacity is under- utilized during slack demand periods while often strained to capacity at peak demand periods. It is standard practice for utilities to categorize their load profiles into base, intermediate, and peak componentsl]~'2 as shown in Figure 7-3. Utilities allocate their most efficient and reliable gen- erating equipment to base load service. Consequently, this base load equipment is typically the newest and most expensive equipment in the utility. Because nuclear reactors are characterized by high Investment costs (per unit output) and have difficulty varying their output to fol- low swings in demand, they are most productively used on a constant basis, operating at their full rated capacity. Currently, nuclear reactors and 92 PAGENO="0372" I 0 366 the best fossil fuel fired plants are always committed to base load service.11'12 The older, less reliable, and less efficient fossil-fired plants are used for intermediate load service, while peak load power is often supplied by inefficient turbine generators (similar to the engines on jet planes that are costly to operate) ~12 However, the high operating costs (for fuel) of turbines is somewhat offset by their low investment cost. When available, hydroelectric power is devoted to intermediate or peak load applications--except in regions with abundant hydro power where it can contribute to base load. To be able to meet very short term var- iations of demand and as a hedge against equipment breakdown, utilities keep a small portion of their spare generating capacity in operation. The amount of this "spinning reserve," is often set in the form of a FIGURE 7-3. TYPICAL LOAD CURVES FOR ELECTRIC POWER GENERATION FOR ONE WEEK. Peak demand is often met by gas or petroleum fueled turbines. 93 PAGENO="0373" 367 systems reliability criterion by the public utility commissions, which regulate utilities. Utilities have shown great interest in finding new ways to follow the swings in the demand load factor, including institutional mechanisms (such as variable pricing) that would tend to smooth demand.17 They have investigated several forms of energy storage, which in effect allows base load facilities to meet some of the intermediate load demand. This effect is shown in Figure 7-4. The most highly developed, although not widely used, form of energy storage is pumped hydroelectric storage.12 This form of energy storage uses off-peak power to pump water uphill to a reservoir and then, during the peak demand periods, the water is re- leased to flow back downhill and generate electricity.'2 However, since locations suitable for the large pumped hydro storage facilities are not common, utilities avidly seek technological analogs to pumped hydroelec- tric storage. SOURCE Ref erence 2. FIGURE 7-4. AVERAGE WINTER WEEKLY ELECTRIC POWER LOAD CURVE 94 PAGENO="0374" 368 Hydrogen can be produced with off-peak power, stored, and then later consumed to generate peak power, thereby serving as a chemical analog to pumped hydroelectric storage.°'10~2 This approach is best matched to nuclear power because it provides a means of converting the otherwise unstorable heat output of a reactor into a storable fuel. There are several optional paths for the round-trip between off-peak electricity through generation and storage and then back to peak elec- tricity; these options are shown in Figure 7-5. Public Service Electric and Gas (PSE&G) in New Jersey is now experimenting--on a small scale-- with the option shown by a heavy line in Figure 7-5; the iron titanium metal hydride storage bed was developed by Brookhaven National Laboratory and is now routinely operated at PSE&G's laboratory.18 The round-trip energy efficiency varies, according to path, but for the liquid hydrogen! fuel cell option it is only about 25 percent; for comparison, pumped hydro storage has a round-trip efficiency of about 66 percent.19 Neither the hydrogen energy storage nor pumped hydro electric storage is particu- larly efficient from an energy point of view, but they offer utilities a means of attacking their peak load problems. As shown in Figure 7-5 the use of hydrogen as an energy storage mechanism paves the way for electric utilities to use fuel cells. Utilities are currently encountering difficulty in expanding their facilities because of land use constraints and other environmental limitations. Nuclear power plant siting is proving especially difficult because of radiation hazard restrictions, cooling water availability, and limitations on the discharge of waste heat. As a result, nuclear power plants are being sited farther and farther from the population centers they serve, and, as a direct result, the amount of land needed for power transmission corridors is directly increased. Aesthetic rea- sons have led to growing public opposition to deployment of new overhead high voltage electric transmission lines and towers. In response to the 95 PAGENO="0375" NOTE SHADING SHOWS SYSTEM UNDER TEST AT PUGLIC SERVICE ELECTRIC a GAS IN NEW JERSEY FIGURE 7-5. HYDROGEN ENERGY STORAGE OPTIONS FOR ELECTRIC UTILITIES (0 PAGENO="0376" 370 difficulties and delay of land acquisition for new corridors of over- head power transmission, utilities are showing increased interest in the high cost technology of underground electric transmission for areas of population density.20 In the future, gaseous hydrogen sent in underground pipelines may offer an aesthetically satisfactory and economically competitive alternative to electric power for long distance energy transmission.~'2° It has been argued that remote siting of nuclear power plants coupled with hydrogen production for energy transmission creates several po- tentially attractive options to electric utilities, as shown in Fig- ure 7~1016,21~22 Although the assumption has never been tested, it is widely believed that, because of the much more favorable aesthetic impact and much reduced commitment of land, it should prove simpler for a utility to secure permission to deploy a single* underground hydrogen pipeline than to deploy an array of overhead electric transmission tow- ers and power lines.23 As discussed in Chapter 12, however, there is not a very good economic match between the normally sized nuclear power plant and hydrogen pipelines. Use of hydrogen for energy transmission would also facili- tate the use of off-peak energy storage and the use of fuel cells to generate electricity. Some utilities have suggested locating the hydrogen_to_electricity generating facilities near the consumer (at the substation level) through use of fuel cells run on hydrogen. Because fuel cells are noiseless and fumeless they should be good neighbors.3 Realization of this concept would require deployment of hydrogen dis- tribution pipelines in the city to serve the fuel-cell equipped sub- stations. A major drawback to this concept for using hydrogen and fuel *For reasons of reliability, however, two pipelines might be desirable. 97 PAGENO="0377" CD Go THERMOCHEMICAL HYDROGEN CYCLES NOTE: THE FINAL ELECTRICITY GENERATION MAY BE BY COMBUSTION UNDER A BOILER, IN A TURBINE, OR IN A FUEL CELL. SINCE TRANSMISSION OF THE OXYGEN BY PIPELINE IS NOT REQUIRED, IT IS SHOWN DASHED FIGURE 7-6. OPTIONS FOR USING HYDROGEN FOR ENERGY TRANSMISSION FROM DISTANT NUCLEAR REACTORS PAGENO="0378" 372 cells is the lowered net energy efficiency of delivered electric power (even when the losses of the alternative electric transmission are in- cluded in the comparison). As long as the same electric utility that originally generated the hydrogen consumed it itself to make electricity there would appear to be few governmental regulatory barriers to the implementation of hydrogen pipelines as a substitute for high voltage electric transmis- sion. Although some electric and gas utilities have suggested the sale of some of their hydrogen,24 it is far from clear that public utilities commissions would allow such sales. Chapter 16 further discusses electric utility applications. 3. Combined Electric and Gas Utilities All the above advantages and disadvantages to the use of hy- drogen apply to a single combined utility serving both gas and electric markets. There is, however, one additional and potentially very impor- tant advantage to a combined utility unavailable to separated utilities: The ability to use hydrogen to load-level both the gas and the electric systems.1° Although they vary by region, climate, and economic activity, the peak annual demands of most electric utilities usually occur in the summer* (because of electric air conditioners) while gas utilities gen- erally experience their peak demand in winter (because of space heating). Thus, a combined utility that sold hydrogen rather than natural gas could load-level electricity in the summer and gas in the winter with the same hydrogen generation and storage facility. The added flexibility and *Electric utilities advertised to promote electric space heating a few years ago in an attempt to create winter demand equivalent to the sum- mer demand. 99 PAGENO="0379" 373 concomitant improvement in hydrogen facility utilization could be ex- pected to have a favorable effect upon the economics of hydrogen as an energy storage medium. C. Automotive Applications 1. Private Passenger Vehicles There is no doubt at all that hydrogen can be used in internal combustion engines to power automobiles,253° Many well-publicized demonstrations have shown that with relatively minor and simple adapta- tions engines run well and cleanly on hydrogen and air (even more cleanly on pure hydrogen and oxygen because NOx cannot form). The ease of adapt- ing stock engines has brought much attention to the clean air advantages of hydrogen fuel in place of gasoline or other chemicals containing carbon.25~4 In addition, some claims have been made that hydrogen in- creases the efficiency of internal combustion engines.35,36* In an environmentally conscious and energy short world, both decreased emis- sions of air pollutants and increased engine efficiency are attractive attributes. The clean air advantage of hydrogen should remain even if external combustion engines displace the internal combustion engine. There are some notable offsetting disadvantages to the use of hydrogen in automobiles. There are really only three potentially prac- tical methods to distribute and store hydrogen for automotive use: (1) as a liquid; (2) in the form of metal hydrides; or (3) in the form *It should be noted, however, that large sized engines generally show better thermal efficiency (because of a smaller surface to volume ratio in the combustion chamber) than small engines. Thus, the trend towards smaller, lighter cars with smaller engines now begun in order to decrease automotive fuel consumption is likely to lessen the net effect of the improved efficiency reported for hydrogen. 100 PAGENO="0380" 374 of hydrogen containing chemical compounds. The last option would include ammonia, NH~, methanol, CH~0H, and others. But, as noted earlier, these compounds have been excluded from our definition of the hydrogen energy economy. The remaining two options are both awkward and fraught with difficulties compared with other fuel options. Use of liquid hydrogen would require the use of cryogenic storage vessels, which are likely to remain bulky and costly compared with the simple sheet metal tank commonly used to hold gasoline--and which would also be suitable for alcohols like methanol. In the small sizes (about 60 gallons) appropriate for hydrogen storage in automobiles, the cryogenic vessels would be thermally inefficient with a boil-off rate of about 1-2 percent per day.37 However, if the car were used regularly, thereby consuming the boil-off hydrogen, no fuel would actually be lost. By far the greatest barrier to the use of' liquid hydrogen in automobiles would be the establishment of a dense liquid hydrogen distribution network. The energy efficiency of the total system of hydrogen produc- tion liquefaction, distribution, storage, transfer, and consumption in automobiles is a parameter of importance. Figure 7-7 shows several op- tions for this chain and compares it to synthetic gasoline from coal. As noted in Chapter 5, the liquefaction of hydrogen is only about 77 per- cent efficient in net energy terms.38 During transfer of liquid hydrogen from one cryogenic storage vessel to another, there is unavoidable boil- off. For reasons of safety (and economics), there can be little doubt that this boil-off would be captured and possibly recycled,33'39 but even reliquefaction of the already cold gas would require a consider- able expenditure of energy--especially if small liquefaction units were used. The energy losses associated with unavoidable boil-off and re- liquefaction at the several transfer points would tend to offset gains in engine efficiency. 101 PAGENO="0381" SYNTHETIC GASOLINE _____________ (63%)' (87'/,I (99%I IIOO%I (22"/,,I~ SYNTHETIC REFINING TO STORAGE, DISTRIBuTION RELATIVE WEIGHT USE IN I COAL CRUDE OIL GASOLINE AND TRANSFER PENALTY FACTOR ENGINE _*` [12%] SYNTHETIC METHANE ____________ 156%)' (93%) (95%) 198%I ____________ COAL_J_____'Rj__METHANE__J-~~--'J_LIQUEFACTION_J_____~STO TIoNj___~R~E~~ FACTOR I-H ~ ~ 112%] SYNTHETIC METHANOL ____________ (4O%l~ 199%) I98'/,) (27%I~ I STORAGE, DISTRIBUTION, RELATIVE WEIGHT USE IN COAL METHANOL AND TRANSFER PENALTY FACTOR ENGINE [IO~/,] METAL HYDRIDE _____________ (59%(1 ,2 (RD%I (B4%)~ I29%I~ METAL HYDRIDE F-H ~ F-H ~ H 112%] LIQUID HYDROGEN 63 ___________ (59~/(S,2 (77%)U 190%I (99%I I29%(~ OTORASE, DISTRIBUTION, RELATIVE WEIGHT USE IN I "1 COAL HYDROGEN LIQUEFACTION AND TRANSFER PENALTY FACTOR ENGINE ~" [2%] u,y~ (33'!,) (80%) (77%(' I90%I (99%) I29'/,I~ NUCLEAR ELECTROLYTIC STORAGE, DISTRIBUTION, RELATIVE WEIGHT UGE IN ELECTRICITY HYDROGEN LIQUEFACTION AND TRANSFER PENALTY FACTOR ENGINE [5%] I "I,) INDIVIDUAL PROCESS EFFICIENCIES [ %~ NET SYSTEM EFFICIENCIES FIGURE 7-7. AUTOMOTIVE SYNTHETIC FUELS SYSTEMS COMPARISON 5% E~TH* HEAT I SREQUIR ED FOR SELF- SUSTAINuNG OFERATION I SEE REFERENCE 361 PAGENO="0382" 376 Metal hydrides seemingly offer an attractive alternative to liquid hydrogen for automotive use.40'41 Many of the candidate hydrides, however, can be eliminated because they do not possess physical proper- ties well suited to the rigors of automotive use. First, many are un- able to release the hydrogen fast enough to keep the car operating unless they are held at a high temperature (around 600°F). Second, the widespread belief that heat from the automotive exhaust system would be adequate to release the needed hydrogen is apparently incorrect--real world heat exchangers are not efficient enough to strike this balance for otherwise suitable metal hydrides.42'43 Third, and perhaps most detrimental to the case for metal hydrides, is the heavy weight and large size (about 700 pounds and 11 cubic feet for even the lightest candidate hydride MgH2) needed to contain enough hydrogen to provide a cruising range equivalent to that provided by present automobile gas tanks in full-sized American cars.44 The present trend toward smaller, lighter automobiles helps the case for metal hydrides on the one hand because the decreased fuel consumption would lessen the weight of the hydrides needed, but, on the other hand, automobile designers would probably be reluctant to relinquish the precious space and weight allo- cations in a small car to a heavy metal hydride bed. Essentially three options are available for distributing and refueling metal hydride beds in automobiles: * Gas recharge in a filling station * Gas recharge in residences * Physical exchange of hydride beds at a filling station. The first two approaches require either the prior existence of a gaseous hydrogen distribution system or small-scale electrolysis units. The heat transfer problems of metal hydride recharge suggest that refueling in a filling station might take longer (15 to 30 minutes)44 than 103 PAGENO="0383" 377 consumers would accept. Recharging at home at night might prove ac- ceptable provided the user never strayed far from home. The physical exchange of an entire depleted metal hydride bed at filling stations loses its intuitive appeal when the awkwardness of accomplishing the rapid exchange of about 700 pounds of bulky material is considered. Moreover, in a viable exchange system the variation allowed in the shape and size of hydride beds would have to be severely limited. Also, if gaseous hydrogen were piped to the filling station the beds could be recharged there, but if a gaseous hydrogen distribu- tion system did not already exist, added burden and energy inefficiency of shipping the hydride beds to and from a central recharging point would be entailed. The attractiveness of hydrogen for private automobiles purely on the basis of engine compatibility and the cause of clean air seems to be more than offset by the new fuel distribution networks and re- fueling procedures required. 2. Fleet Vehicles Fleets of cars, trucks, and buses presently consume about 30 percent of all fuel used in the automotive sector. Because trucks and buses are bulky themselves, the bulkiness of a large liquid hydrogen or metal hydride fuel system would be less constraining than in auto- mobiles. Many fleet vehicles often do not travel far from their home terminals where they are refueled. Moreover, because they frequently are idle for much of the night, a prolonged refueling operation--as for metal hydride storage--need not be as constraining. Many other fleet vehicles operate repetitively between the. fixed end points. Thus, the complications of refueling with either liquid hydrogen or a slow 104 PAGENO="0384" 378 recharging of a metal hydride can often be tolerated for fleet vehicles. Consequently, the use of hydrogen could be implemented far more readily in fleet vehicles than in private automobiles. 3. Off-the-Road Vehicles While in principle off-the-road vehicles such as earthmovers, farm machinery, mining machinery, snowmobiles, motorcycles, forklifts, and so forth could all be run on hydrogen, the problems of on-board fuel storage and distribution to the vehicles is acute. There are a few exceptional cases, however, in which the especially advantageous properties of hydrogen combustion may offset these difficulties. Fork- lifts used indoors in warehouses are one of the prime examples.45 Al- ready, to avoid carbon monoxide poisoning in confined environments, most forklifts used indoors are either battery-electric or operated on rela- tively clean burning liquid propane, butane, or compressed methane. Hydrogen combustion's complete lack of toxic carbon monoxide exhaust products would, therefore, place a hydrogen fueled forklift on a par with an electric forklift--as far as emissions are concerned. In such uses, the occupational health advantages of hydrogen could even justify payment of a premium price for the fuel. Chapter 14 further discusses automotive applications. D. Aircraft Applications Tests have proved that jet aircraft engines run well and very cleanly on hydrogen.~548 Under contract to NASA, Lockheed has recently completed a thoughtful analysis and evaluation of the design options available for hydrogen fueled supersonic49 and subsonic transport5° aircraft. For both kinds of aircraft, the only viable form of hydrogen storage is the cryogenic liquid. 105 PAGENO="0385" 379 For hypersonic (more than five times the speed of sound) aircraft, liquid hydrogen is vastly superior to conventional jet fuels because it can be used enroute to the engines to cool the aircraft skin, which is heated by aerodynamic drag. This advantageous synergism allows the use of lightweight materials such as aluminum instead of heavy, high- temperature materials, thereby reducing the weight of the aircraft.5154 Hydrogen's advantage over conventional jet fuel is not so great in subsonic aircraft as in hypersonic aircraft. The recent studies by Lock- heed have shown that an optimized liquid hydrogen fueled subsonic passen- ger plane would possess the following attributes (compared with an ad- vanced design airplane using conventional jet fuel) :50 * Less gross take-off weight * Nearly equal empty weight * Lower emissions of air pollutants (only nitrogen oxides) * Shorter take-off distance (about 36 percent reduction) * Less noise in the take-off zone * Slightly more noise in the landing zone * Slightly higher aircraft sales price (about 3 percent) * Lower energy utilization per passenger mile. These and other comparisons are shown in Table 7-1 for both transocean and transcontinental versions. It must be emphasized that in the Lock- heed study it was assumed that future airplanes using either fuel will be less noisy than the quietest U.S. -made airplanes now flying.50* Because liquid hydrogen contains only about one-third the energy in the same volume as the conventional fuel (Jet A, essentially kerosene), the volume required for fuel storage is much larger in a hydrogen-fueled *The wide-body Lockheed LlOll, McDonnell-Douglas DC-lO, and Boeing 747. 106 62-332 0 - 76 - 25 PAGENO="0386" Table 7-1 COMPARISON OF Lu2 AND JET A PASSENGER AIRCRAFT 5500 nmi, Mach 0.85 ~LH JetA Unit -~ 3000 nmi, Mach 0.85 _______ Jet_A Energy utilization Btu/seat nmi 1,239 1,384 1,204 1,260 0 Gross weight 212,900 210,600 Operating empty weight lb 242,100 28,000 82,300 Block fuel weight lb 52,900 165,500 24,720 25,770 Thrust per engine lb 28,700 Span ft 174 59.5 194.1 60.2 165.6 55.4 170.6 56.0 Height ft 219 197 210 197 Fuselage length ft 3,047 3,235 Wing area ft2 3,363 4,186 Take-off distance ft 6,240 7,990 5,860 5,804 7,980 5,760 Landing distance ft 5,810 5,210 Aircraft price $ million 26.9 26.5 23.4 22.6 CA~ Source: Lockheed, Reference 50. PAGENO="0387" 381 airplane than in a conventional jet. Although today's commercial air- planes carry Jet A fuel in tanks formed by the wing structure, hydrogen cannot be carried in the wings because of insufficient space and also because the shape of the available space would result in very inefficient containment (high surface to volume ratio).~ Lockheed considered several locations for liquid hydrogen fuel storage including large over-the-wing pods; tanks inside the fuselage, both above or below the passenger cabin; and tanks inside the fuselage in front of and behind the passenger cabin.60 Lockheed concluded that from safety, structural, and effec- tiveness points Of view the last option was superior.6° Figure 7-8 (a and b) shows the designs Lockheed considered; the internal tank version was selected for the most detailed analysis. As shown in Figures 7-8b and 7-9, the selected airplane looks remarkably like conventional wide- body jets from both the side and plan views. The large size of the fuel storage volume makes it fairly clear that large, long-range aircraft are best suited for liquid hydrogen fuel. A commercial fleet of liquid hydrogen airplanes would require the production of vast quantities of hydrogen and a large throughput in the logistics system. Such a fuel network, however, would require relatively few distribution points55 because the top 25 airports in the country han- dle about 76 percent of all the air passengers, and the top 10 airports handle about 70 percent of all the passengers.68 Thus, with as few as 10 airports equipped to dispense the fuel, a great proportion of the long-distance travel in liquid-hydrogen-fueled aircraft could be accom- modated. Small general aviation aircraft could, in principle, use liquid hydrogen, but the large size of the fuel tanks is an impediment. In addition, it would be extremely difficult to supply liquid hydrogen to the large number of general aviation airports and landing strips. 108 PAGENO="0388" 382 FIGURE 7-8. OPTIONS FOR HYDROGEN STORAGE IN AIRCRAFT CABIN DOUBLE DECK _________ 12 PER ROW (a) SELECTED EXTERNAL TANK CONFIGURATION LH2 PASSENGER AIRCRAFT (400 PASSENGER, 5500 N.MI.) (b) SELECTED INTERNAL TANK CONFIGURATION LH2 PASSENGER AIRCRAFT (400 PASSENGER, 5500 N.MI.) SOURCE LOCKHEED, REFERENCE 50 109 PAGENO="0389" 383 LH2 JET A SPAN 74 194 WING AREA 3360 4180 BODY LENGTH 219 97 N 0.85, 5500 nmi SOURCE: LOCKHEED, REFERENCE 50 FIGURE 7-9. SIZE COMPARISON: LH2 vs JET A PASSENGER AIRCRAFT E. Ship, Train, Spacecraft Applications Hydrogen's demonstrated suitability for combustion in nearly every class of engine implies that there should be no major technological bar- riers to its use in either ships or trains. Liquid hydrogen is already an essential fuel for spacecraft and this single use (as opposed to cap- tively produced and used hydrogen) constitutes, by far, the largest con- temporary market for merchant hydrogen. Since ships are not so limited by their size and shape as automo- biles and trucks, there should be little barrier from the extra volume needed to store liquid hydrogen. Storage as a metal hydride, however, probably weighs too much to be taken seriously. Yet there does not seem to be much advantage or incentive for the use of hydrogen in large JET A AIRPLANE SHOWN SHADED 110 PAGENO="0390" 384 ships. Ships are generally fueled either by a low grade heavy oil (bunker fuel) or by diesel. Air pollution caused by ships--especially ocean going ships--has not been a problem because most of their opera- tions are far from population centers and, more importantly, beyond the regulatory control of any government. The need to establish a global liquid hydrogen network would be a strong disincentive to the conversion of ocean-going ships to other than fuel oil. Trains are not strongly constrained in their total volume although they are severely limited in cross section (set by the clearance dimen- sions of tunnels, bridges, parallel tracks, etc.). Use of hydrogen to fuel gas turbine trains would certainly reduce air pollution and, pos- sibly, engine noise. Advanced design turbine powered trains are under development both in this country and abroad although the effort receives only modest funding. Getting the fuel to the trains would be relatively simple compared to other land transportation applications of hydrogen. The train can carry a large fuel supply and can be operated between fixed, even though distant, end-points, thereby greatly reducing the number of fueling points needed. It has now been demonstrated (with models) that magnetic levitation using superconducting electromagnets is technically feasible for a train running on special guideways.a7~ae To date all work on this problem has assumed that liquid helium would be used as the cryogenic coolant for * the magnets because superconductors with transition temperatures higher *Superconductors are characterized by several physical parameters. The "transition temperature" is the temperature at which the material under- goes a transition from being a normal, resistive, conductor to a super- conducting, resistanceless, material. To operate superconducting equip- ment at the normal liquid hydrogen boiling temperatures of 20.4°K requires a superconductor with a transition temperature several degrees higher. 111 PAGENO="0391" than the normal boiling point of liquid hydrogen have been found only recently. The expectation that superconductors with still higher transi- tion temperatures may yet be found means that in the future liquid hydro- gen might serve as the cryogenic coolant instead of the more expensive and more scarce liquid helium. Conceivably, a magnetic levitation train could utilize the hydrogen both as a coolant and then as fuel. Such ap- plication is many years away and would probably be confined to high- speed passenger trains. For spacecraft, liquid hydrogen is a nearly ideal fuel because its very high gravimetric energy density greatly reduces the total launch weight of a rocket. Liquid hydrogen (combusted with pure oxygen) is the standard fuel for the second and third stages of U.S. space exploration rockets. However, because of the need to maintain constant readiness, hydrogen is not now used extensively in present military nuclear warhead missiles. NASA is still developing and designing the space shuttle, a reusable rocket with a high payload capability that is envisioned for use in space activities close to earth. For example, the proposed large satellite- borne solar energy collector that would transmit the energy to earth on a microwave beam would use the space shuttle to ferry construction mate- rial into orbit. Construction of this huge solar energy device would require from 300 to 1000 ferry trips of a second generation space shuttle.69 Although deployment of this solar energy satellite is ques- tionable, this or comparable use of the space shuttle would require vast quantities of hydrogen. Chapter 15 further discusses aviation applications. 112 PAGENO="0392" 386 F. Military Applications Just as in the civilian sector, there is potential for military use of hydrogen in cars, trucks, buses, ships, and airplanes. There has been discussion (mainly among civilians) of a nuclear powered aircraft car- rier that could use electrolytically derived liquid hydrogen to fuel the carrier's jets. At first sight, the ability to make hydrogen anywhere in the world from any basic energy resource would seem to have considerable appeal to the military because it might eliminate burdensome, long energy sup- ply logistics systems. With more thought, however, the attractiveness of hydrogen in mili- tary applications fades for several reasons. First, the bulkiness of hydrogen fuel storage contradicts the need for small, sleek, highly maneuverable, supersonic, fighter aircraft; bulkiness also discourages hydrogen use in land vehicles such as tanks because it would increase their size as a target. Second, hydrogen production could not com- pletely eliminate the logistics supply line because in most cases some basic energy resource would still have to be delivered. Third, the extra procedures and precautions needed to liquify and handle vast quan- tities of cryogenic hydrogen are not very compatible with combat. Fourth, the military requires great operational flexibility and it would be undesirable to have some airplanes for example fueled with hydrogen while others used conventional jet fuel. Military use of hydrogen seems to compromise, rather than improve, readiness, flexibility, vulnerability. This accounts no doubt for the present low level of enthusiasm in both the civilian and uniformed mili- tary establishment for military use of hydrogen as a fuel. This lack of military interest has very important ramifications for the evolution of the hydrogen energy economy and the need for civilian 113 PAGENO="0393" 387 sponsored research and development. Historically, military needs have been the stimulus for much technological development with subsequent "spin-off" into the civilian sector. G. Chemical Applications Besides use as a fuel, hydrogen has many applications as a chemical because it is an excellent chemical reducing agent.* It is essential in reforming hydrocarbons (such as making plastics from oil), and it is necessary for synthesizing other important chemicals such as ammonia. It would be naive to expect that the hydrogen energy economy concept could develop without strong synergisms developing between it and the hydrogen chemical economy.4 1. Ammonia Synthesis Ammonia, NH3, is one of the most basic chemicals used in mod- ern industrial society.6° It is used as a feedstock for many chemical processes and as a fertilizert--either directly or transformed into ammonium sulfate, nitrate or urea.60 Production of ammonia has grown rapidly recently, and the increasing emphasis on expanded agricultural output by putting more lands in cultivation is likely to spur yet more growth. However growth in the use of ammonia as a fertilizer is bound to level off soon in the United States because fertilizer application rates are nearing their optimum economic usage.el *Chemical reduction is essentially the inverse of oxidation, and in many reducing applications, hydrogen is used to remove oxygen from a compound. For example, iron oxide, Fe203, can be reduced with hydro- gen to yield iron. ~Nitrogen is a key element in controlling plant growth. The nitrogen in ammonia or the ammonium ion is readily available for plant uptake. 114 PAGENO="0394" 388 At the present time production of essentially all ammonia in the United States is accomplished by synthesis from a nitrogen-hydrogen gas mixture derived from air and methane.4'61'62 Methane is reformed (by the process described in Chapter 4) to yield hydrogen. The required nitrogen is obtained by burning methane in air to consume the oxygen in air and then chemically separating the carbon dioxide and water combus- tion products to yield the nitrogen.61* The heat derived from the methane combustion is used as process heat. Ammonia synthesis from a methane feedstock is a very well understood, highly developed, highly efficient technology in which there is little room for improvement.61 In the United States methane has tra- ditionally been both the source of hydrogen and process heat because it has been abundant and cheap.61 Most ammonia plants have been located near the methane sources; the majority are now located in an arc around the U.S. Gulf of Mexico coast and the Southwest.6' It is frequently stated that ammonia synthesis will provide a large market for hydrogen in the future hydrogen economy.36 The reason- ing has been that as methane supplies dwindle and the price rises, am- monia producers will be priced out of methane. They would then turn to hydrogen as a feedstock provided it were available for purchase, alter- natively, they might make it themselves electrolytically. This line of reasoning has been fostered by a misunderstanding of the design of actual ammonia synthesis plants. In particular, because the role of methane in providing the nitrogen is not widely known, it was easy to assume that the abandonment of methane as a feedstock would only affect the plant's source of hydrogen. But, in fact, because the designs have been so *Air is composed mainly of gaseous oxygen (about 20 percent) and gaseous nitrogen (about 80 percent). 115 PAGENO="0395" 389 highly integrated, abandonment of methane would necessitate redesign of nearly the entire plant.61 Experts in ammonia production report that if methane were not available as a feedstock to an ammonia synthesis plant, it would prove more effective to turn to nearly any alternative liquid or gaseous hydrocarbon in preference to hydrogen because this would re- sult in the smallest overall change in the existing plant designs and operations.61 However, if hydrogen became available at a lower cost than it could be obtained from methane or alternative hydrocarbon fuels, it is probable that new ammonia plants would be designed to use the lower cost hydrogen feedstock.61 There is no inherent technological reason why new ammonia plants could not be designed to use a hydrogen feed- stock. Chapter 17 further discusses the likelihood of ammonia synthesis becoming a significant portion of the hydrogen economy. 2. Coal Gasification or Liquefaction As noted in Chapters 4 and 11, for the foreseeable future the cheapest source of hydrogen not based on liquid or gaseous fossil fuels will be coal gasification. Yet coal gasification (and also liquefac- *tion) processes that yield methane (or synthetic crude oil) could be made more efficient in their use of coal if an independent source of hydrogen were available. Some, therefore, envision hydrogen derived from nuclear energy finding a market in the coal gasification or lique- faction industry.S This proposed application of merchant hydrogen, however, is not very likely to be realized. In the first place, it would prove less efficient to use nuclear power to produce hydrogen as a distinct intermediate product than to use the nuclear power for process heat in the gasification or liquefaction process. Second, if nuclear derived hydrogen could be purchased for the process more cheaply than it could be produced from the coal, it would make little economic sense to 116 PAGENO="0396" 390 manufacture high cost synthetic methane when low-cost hydrogen was available as competitor. Thus, it appears that although coal gasifica- tion and liquefaction technologies will eventually be deployed and will require hydrogen, the hydrogen will be derived from the energy of coal itself. Similar conclusions apply to the hydrogenation steps in oil shale processing and the production of methanol from coal and various waste materials. 3. Minor Chemical Uses Hydrogen is used today in the food industry to transform "un- saturated" fats to "saturated" fats. This occurs, for example, in the margarine, peanut butter, and shortening industries.4 These chemical feedstock uses of hydrogen would constitute only a tiny portion of the hydrogen economy. Moreover, they do not appear destined to play a piv- otal role in the hydrogen economy evolution and are not considered further. 4. Chemical Reduction There are many industries in which chemical reduction is em- ployed; for example, to transform an oxide or sulfide metal ore into a raw metal, and to remove oxidation from a surface prior to plating or finishing. Steel-making with hydrogen used as an iron ore reducing agent is becoming increasingly attractive and is likely to develop into a major use of hydrogen.4'6365 In steel-making, the ore is iron-oxide. The first step in steel-making is to chemically reduce the ore to raw iron. To achieve this reduction, a special class of coal, called "metallurgical" or "coking" coal is required. Coal is turned into coke, a spongy form of pure carbon,64 by a destructive distillation process. Volatile gases 117 PAGENO="0397" 391 driven off during the coking process are burned to provide the process heat.64 Coke and raw iron ore are then mixed together and heated.64 Because the oxygen is more attracted to the carbon than the iron at elevated temperatures, the ore is chemically changed into (impure) metallic iron and the carbon combines with the oxygen to yield carbon dioxide (C02), and some carbon monoxide (CO). In the early days of steel-making, charcoal was used instead of coke. The combined need for both iron ore and coal dictated the locations of iron and steel-making insta llations 64 Most large steel companies in the United States are vertically integrated and control and mine their own resources of coking coal. Not all countries are as well endowed with coal suitable for coking as is the United States and considerable quantities of eastern coal are ex- ported each year for steel-making purposes--especially to Japan, which has no suitable indigenous resources.63 Coking coal resources are be- coming increasingly scarce and expensive,64 and the control of air pollu- tion from coke making and ore reduction is increasingly being forced on a steel industry reluctant to make the investments in the necessary air pollution control equipment.6668 Both factors are serving to enhance interest in new ways of steel-making. Nuclear steel-making, and hydrogen used for ore reduction, are being looked on with new favor.6~'65 As presently conceived, nuclear steel-making makes use of the heat of a nuclear reactor both to yield process heat and to generate electricity for the electric arc furnaces, which melt the raw iron for transformation into steel.63 Part of the nuclear energy could be used to make hydrogen for ore reduction. The source of hydrogen envisioned is usually methane with the nuclear reac- tor supplying the heat needed for reformation.63'65 However, as methane becomes less available, no doubt emphasis will shift to obtaining the hydrogen either by electrolysis or by thermochemical cycles. In any 118 PAGENO="0398" 392 event, the vast quantities of hydrogen involved and the presence of an on-site nuclear reactor suggest that this hydrogen will be produced captively rather than purchased. Currently the major interest in nuclear steel-making and hy- drogen reduction of ore is found in foreign nations--especially Japan and England.63 However, in this country, Bethlehem Steel is apparently taking some interest.65 Chapter 17 further discusses hydrogen's use in steel-making. H. Cryogenic Applications Liquid hydrogen has the second lowest boiling point of any liquid, as can be seen in Table 7-2. Because until recently no materials had been found that were superconducting above 20.4°K, there was no possi- bility of using liquid hydrogen to cool superconducting equipment. Recently, however, it has been found that Nb3Ge superconducts at about 23°K and below.6971 Thus, there is widespread hope that other materials will be found with even higher superconducting transition temperatures, thereby opening the way to use liquid hydrogen as a coolant instead of the usual liquid helium.70 This recent discovery is very important for several reasons. First, it takes more energy to liquefy helium than hydrogen. (The theoretical minimum for helium is about twice that of hydrogen.)72 Second, helium is a rare element mainly found in a dilute (2 percent) association with natural gas from a few fields.73'74 Although the United States has most of the world's reserves of helium, and until recently was building a stockpile for future use, additions to the storage program have been terminated by the federal government.74 Consequently, helium is now being wasted into the atmosphere as the natural gas is burned. Moreover, only two gases, helium and hydrogen, are light enough to escape the 119 PAGENO="0399" 393 earth's gravity; hence, helium diffuses through the atmosphere and is permanently lost into outer space. Many technologists question whether terrestrial reserves of helium will be adequate to sustain large-scale industrial use of superconducting technology unless the wastage of helium is stopped.73'74 Table 7-2 NORMAL BOILING POINT OF CRYOGENIC LIQUIDS Temperature Element (°K) (°C) (°F) Helium (He) 4.2 -269 -452 Hydrogen (H2) 20.4 -253 -423 Neon (Ne) 27 -246 -411 Nitrogen (N2) 77 -196 -320 Argon (Ar) 87 -186 -303 Oxygen (02) 90 -183 -297 Methane (CM4) 112 -162 -259 If additional and useful new materials are found that will super- conduct in liquid hydrogen, important new uses75 for the hydrogen will be established. Important synergisms with other aspects of the hydrogen economy would be inevitable. Uses of cryogenic liquids not involving superconductors are in- creasing. Today, nearly all these applications use either liquid helium or the far cheaper liquid nitrogen. Once widely available com- mercially, the coldness of liquid hydrogen would surely find many ap- plications. Some of the diverse potential uses of cryogenic liquids are the following: 120 PAGENO="0400" 394 * Refrigeration * Freeze drying of foods76 * Embrittlement of materials to enhance fracturing as a prelude to separation and recycling. It is likely that boil-off from liquid hydrogen used as a coolant would be trapped and then consumed as a fuel by the user. 121 PAGENO="0401" 395 REFERENCES 1. `Project Independence," Project Independence Report, Federal Energy Administration (November 1974). 2. G. T. Kinney, "U.S. Gas Picture Darkens While SNG and LNG Lag," Oil and Gas Journal (16 June 1975), pp. 17-20. 3. D. P. Gregory et al., "A Hydrogen-Energy System," American Gas Association, Alexandria, Virginia (August 1972). 4. E. Fein, "A Hydrogen Based Energy Economy," The Futures Group, Glastonbury, Connecticut (October 1972). 5. L. T. 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(Plenum Press, New York, 1975), pp. 765-778. 44. C. H. Waide, J. J. Reilly, R. H. Wiswall, "The Application of Metal Hydrides to Ground Transport," in Hydrogen Energy, T. N. Veziroglu, ed. (Plenum Press, New York, 1975), pp. 779-790. 45. R. D. Witcof ski, "Prospects for Hydrogen-Fueled Aircraft," in Pro- ceedings of the Cornell International Symposium and Workshop on the Hydrogen Economy, S. Linke, ed. (Cornell University, Ithaca, New York, April 1975), pp. 315-327. 125 PAGENO="0405" 399 46. "Working Symposium on Liquid-Hydrogen-Fueled Aircraft," National Aeronautics and Space Administration, Langley Research Center, Hampton, Virginia, 15-16 May 1973. 47. G. D. Brewer, "The Case for Hydrogen-Fueled Transport Aircraft," Astronautics and Aeronautics (May 1974), pp. 40-51. 48. C. Covault, "Fuel Shortages Spur Hydrogen Interest," Aviation Week and Space Technology (17 December 1973), pp. 38-42. 49. G. D. Brewer, "Advanced Supersonic Technology Concept Study--Hydro- gen Fueled Comparison," National Aeronautics and Space Administra- tion, Contract NAS 2-7732, Ames Research Center, Ames, Iowa (January 1974). 50. G. D. Brewer et al., "Study of the Application of Hydrogen Fuel to Long Range Subsonic Transport Aircraft," National Aeronautics and Space Administration, Langley Research Center, Hampton, Virginia (January 1975). 51. "Development of Liquid-Hydrogen Scramjet Key to Hypersonic Flight," Aviation Week and Space Technology (17 September 1973), pp. 75-78. 52. "Hypersonic Aircraft by 2000 Pushed," Aviation Week and Space Technology (17 September 1973), pp. 52-57. 53. J. V. Becker, "New Approaches to Hypersonic Aircraft," paper pre- sented at the 7th Congress of the International Council of the Aero- nautical Sciences, Rome, Italy, 14-18 September 1970. 54. A. L. Nagel and J. V. Becker, "Key Technology for Airbreathing Hypersonic Aircraft," paper presented at the 9th annual meeting of the American Institute of Aeronautics and Astronautics, Wash- ington, D.C., 8-10 January 1973. 55. C. R. Dyer, M. Z. Sincoff, P. D. Cribbins, eds., "The Energy Dilemma and Its Impact on Air Transportation," National Aeronautics and Space Administration-American Society for Engineering Education, Langley Research Center, Hampton, Virginia (1973). 56. "The Long Range Needs of Aviation," a report of the Aviation Advis- ory Commission, Washington, D.C. (January 1973). 57. H. H. Kolm and R. D. Thorton, "Electromagnetic Flight," Scientific American (October 1973), pp. 17-25. 126 PAGENO="0406" 400 58. R. A. Hem, Superconductivity: Large-Scale Applications," Science (19 July 1974), PP. 211-222. 59. P. E. Glaser, "Satellite Solar Power Station: An Option of Power Generation," 7th Intersociety Energy Conversion Engineering Con- ference, 1972. 60. P. Meadows and J. A. DeCarlo, "Hydrogen," in Mineral Facts and Problems, Bureau of Mines Bulletin 650 (1970). 61. Mr. Robert Muller, Stamford Research Institute, Menlo Park, Cali- fornia (personal communication). 62. "Pushing for Priority," Chemical Week (3 April 1974), p. 15. 63. N. Valery, "Steelmaking with Heat from the Atom," New Scientist 13 September 1973), pp. 610-615. 64. R. J. Leary and G. M. Larwood, "Effects of Direct Reduction Upon Mineral Supply Requirements for Iron and Steel Production," Bureau of Mines Information Circular 8583 (1973). 65. D. 3. Blickwede and T. F. Barnhardt, "The Use of Nuclear Energy in Steelmaking," paper presented at the First National Topical Meeting on Nuclear Process Heat Applications, Los Alarnos Scientific Labo- ratory, Los Alamos, New Mexico, 1-3 October 1974. *66. "The New Economics of World Steelmaking," Business Week (3 August 1974), pp. 34-39. 67. "Coke Oven Control Program Could Cost Bethlehem Steel $40 Million," Air/Water Pollution Report (28 October 1974), p. 428. 68. "A Search for Clean Coking Processes," Steel Facts, Number 1, American Iron and Steel Institute, Washington, D.C. (1974). 69. A.L. Robinson, "Materials Science: Superconductivity Heats Up," Science (28 December 1973), p. 1334. 70. A. L. Robinson, "Superconductivity: Surpassing the Hydrogen Bar- rier," Science (25 January 1974), pp. 293-296. 71. "Record Heat for Supercold Alloy," Industrial Research (December 1973), p. 20. 127 PAGENO="0407" 401 72. R. F. Barron, "Liquefaction Cycles for Cryogens," in Advances in Cryogenic Engineering, 17, K. D. Timmerhaus, ed. (Plenum Press, New York, 1972), pp. 20-36. 73. W. D. Metz, "Helium Conservation Program: Casting It to the Winds," Science (11 January 1974), pp. 59-63. 74. C. A. Price, "The Helium Conservation Program of the Department of the Interior," in Patient Earth, J. Harte and R. H. Socolow, eds. (Holt, Rinehart and Winston, New York, 1971). 75. R. A. Hem, "Superconductivity: Large-Scale Applications," Science (19 July 1974), pp. 211-222. 76. K. Imatani and K. D. Timmerhaus, "Current Status of Cryogenic and Air-Blast Food Freezing Systems," in Advances in Cryogenic Engi neering, 17, K. D. Timmerhaus, ed. (Plenum Press, New York, 1972), pp. 137-146. 128 PAGENO="0408" 402 CHAPTER 8--HYDROGEN SAFETY A. Complexity of the Safety Question The safety of hydrogen compared with commonly used fuels is a com- plicated question, with no clear-cut answers. Among those in the tech- nical community who have no direct contact or operating experience, there is widespread belief that hydrogen is a dangerous substance that burns and explodes readily. Hydrogen economy enthusiasts often argue, however, that, if it is used properly, hydrogen is really no more dan- gerous than the familiar fuels--methane (natural gas), gasoline, diesel, propane, and kerosene (jet fuel) .~ ~2 Neither attitude is completely correct because the hazards of any substance are circumstantial and depend on the nature and environment of use as well as on whether the moment is routine or extraordinary. It can be said, however, that since the physical and chemical properties of hydrogen are quite different from commonly encountered substances the hazards associated with hydrogen appear to be far more circumstan- tial than for other fuels. This chapter examines the physical and chemical aspects of hydrogen safety, and also social aspects, such as the importance of peoples' per- ceptions about hydrogen safety and the distinction between voluntary and involuntary exposure to risk. It will be seen that blanket state- ments about the safety of hydrogen relative to other substances are gen- erally misleading. 129 PAGENO="0409" 403 B. Properties of. Hydrogen The physical and chemical properties of hydrogen, methane, gasoline, and jet fuel relevant to safety are shown in Table 8-1. The most impor- tant points about hydrogen to note are the following: * Liquid hydrogen is a very cold substance (-452°F). * Gaseous hydrogen at room temperatures has a very low density compared with that of air and thus is very buoyant.1'3'4 * Gaseous hydrogen diffuses* through air very quickly.1'3 * Hydrogen is flammable in air over a wide range of concentrations, much more so than methane (natural gas) .``~`~ * When confined hydrogen is detomatable over a wide range of con- centrations1'3 but when unconfined it is difficult to make it detonate. * Hydrogen can be ignited by a very small amount of energy. * Hydrogen flames travel much faster than methane f lames.1'3 * Hydrogen flames are nearly invisible.1'3 C. Hydrogen Behavior Liquid hydrogen spilling from a large rupture in a large storage tank, would be dramatic: the liquid hydrogen, its temperature well below the usual ambient temperature, would quickly draw heat from the surroundings and vaporize rapidly. The cold hydrogen gas would occupy about 50 times the volume it did as a liquid. As the cold gas continued to draw heat from the surroundings and to warm up, water vapor in the chilled surrounding air would condense or freeze and form a dense white *Buoyancy and diffusivity are different phenomena: Buoyancy describes the rate that a packet or cloud or gas would move intact; diffusivity describes the rate that an individual molecule would penetrate through a volume of another gas. Both parameters are required to describe how rapidly a cloud of hydrogen would disperse in air. 130 PAGENO="0410" Table 8-1 PROPERTIES OF HYDROGEN AND OTHER COMMON FUELS RELEVANT TO SAFETY Property ______________ ______________ __________________ Temperature of liquid at normal boiling point Heat o vaporization Density of saturated vapor (at normal boiling point) relative to the density of air Density of gas relative to the density of air (at STP) Diffusion coefficient Hydrogen (112) Methane (CH4) Methanol (CII3OH) 2O.3~K 0.45 MJ/kg 1.05 ll2~K 338~K 0.51 MJ/kg 1.38 0.070 0.55 2 2 0.63 cm /sec 0.2 cm /sec Gasoline Jet Fuel (JP-4) 398~K 372~K 0.08 cm2/sec Flammability limits in (4.1-74)% (5.3-15)% (6.O-37)% (1.5-7.6)% (0.8-5.6)% air (by volume) Detonatability limits in (18-59)% (6.3-14)% air (by volume) Ignition temperature 850 K 807 K 700 K 530 K 522 K Ignition energy 20 pJ 300 ~iJ 250~tJ* Flame temperature 2400 K 2190 K Flame velocity 2.75 m/sec 0.37 m/sec <0.3 m/sec* ` Quenching distance 0.06 cm 0.23 cm >0.25 cm* Emissivity of flame 0.10 1.0 Heat of combustion 120 MJ/kg 8.5 GJ/m3 50 MJ/kg 21 GJ/m3 20 MJ/kg 16 GJ/m3 44 MJ/kg 31 GJ/m3 43 MJ/kg 34 GJ/m3 Estimated in Reference 2. PAGENO="0411" 405 cloud of fog. Some oxygen and nitrogen in the air would also condense or freeze. Nearby objects would contract as they underwent rapid cool- ing, giving off noises. As the volume of hydrogen gas warmed it would continue to expand and, when it became less dense than the chilled air surrounding it, it would rise buoyantly above the spill. Simultaneously, individual molecules of hydrogen would diffuse from the volume of gas in all directions. If the spill were in an open environment such as out of doors or under a simple canopy, the hydrogen would disperse quickly. But if it occurred in a building, the hydrogen could be trapped and the large change in *hydrogen volume upon vaporization would force air out from the environment. The extent and rate of dispersal and the nature of the nearby objects would determine whether the hydrogen would ignite. Figure 8-1 depicts the observed dispersal of flames from a small spill of liquid hydrogen that has ignited;5 note that in 2 seconds the flames are nearly all dispersed upwards. Extreme care must be exercized, how- ever, in drawing inferences from this figure about the behavior of a 80 60 ~40 SOURCE: Rel,r.ncs 5 FIGURE 8-1. MAXIMUM VERTICAL CROSS SECTIONS OF FLAMES PRODUCED AT VARIOUS TIME INTERVALS FOLLOWING SPILLAGE OF ~9 LITERS OF LIQUID HYDROGEN ON A GRAVEL SURFACE (Ha. Scale ~ Ver. Scale) ELAPSED TIME, seconds Q 132 PAGENO="0412" 406 large* spill. If liquid hydrogen were to leak from a small orifice, the effects would be less dramatic than in a large rupture spill but they would still be impressive, especially since a stream leaking from a small orifice often ignites because of static electric discharges.6 The description above illustrates that blanket statements about hydrogen safety are inadequate because the final result of the spill depends upon the nature of the rupture, the degree of confinement, the nature of the actual nearby objects, and whether combustion is initiated. With the present state of knowledge about hydrogen and its accidents, discussions of its safety usually assume the form of "on the one hand this, but on the other hand that." Some of these kinds of discussions follow. The wide range of flammability of hydrogen in air suggests that a leak of hydrogen is more likely to result in a fire than a leak of methane. For example, hydrogen can ignite when the atmosphere is 50 per- cent hydrogen while, at the same percentage, methane cannot. After a leak, however, the fuel concentration builds up from zero and ignition (if an ignition source is present) is most likely to occur when the con- centration first reaches the lower flammability limit.1'3'4 If the con- centration passes this level without igniting, then most likely ~there are no ignition sources present and ignition will not occur directly. Consequently, the lower flammability limit is really most important irrespective of the total range.1'3'4 Table 8-1 shows that in this respect hydrogen is similar to methane, a fuel that most people regard as acceptably safe.t The ignition energy parameter is also relevant *Reca]J that a railroad tank car holds about 28,000 gallons of liquid hydrogen. This is more than 1000 times larger than the spill shown in Figure 8-1. tThis attitude prevails in spite of more than 39 deaths and 218 injuries in the first half of 1973 alone from accidents with natural gas, many of them in residences.1° 133 PAGENO="0413" 407 here, however. Table 8-1 shows that hydrogen can be ignited by only about 1/15 the energy required to ignite methane, which greatly in- creases the likelihood of hydrogen ignition. For example, synthetic fibers in clothes cause electrostatic sparks, many of which are imper- ceptible to the wearer but which are energetic enough to ignite hy- drogen.7 The wide detonatability limits of hydrogen lead to an analysis similar to the above. Yet in often-mentioned experiments in 1960, the consulting firm of Arthur D. Little, Inc., was unable to detonate hydro- gen after creating spills of liquid hydrogen up to 5000 gallons in volume.8 Other workers, however, insist that hydrogen is readily det- onated and report accidents.9 The discrepancy in experience appears to be traceable to the presence of walls and other obstacles which can reflect pressure waves. When pure hydrogen (assuming no flame colorant has been added) burns, the flame is nearly invisible in daylight because little energy is radiated.1 While the invisibility of the flame makes the fire diff i- cult to locate and fight, firefighters can get very close to the flame (assuming they know where it is) without injury. Since it i~s also dif- ficult to feel warmth from the flame, a person can easily move right into the flame and be burned; but surrounding objects do not heat up and ignite unless touched by the flame directly. In normal fires, one of the major causes of fire spreading and injury is the large amount of energy radiated by oxidizing carbon atoms. Thus, the lack of flame luminosity in hydrogen fires can be both a help and a hindrance. The energy radiated from fires above pools of liquid hydrogen and liquid methane of the same area and volume would be nearly identical because the lower emissivity of hydrogen is offset by the more rapid rate of combustion.7 Of course, this also means that the available 134 PAGENO="0414" 408 fuel is more quickly exhausted in the hydrogen fire. However, owing to its rapid rate of evaporation, pools of liquid hydrogen are not likely to form except after a very large spill. A liquid-hydrogen-fueled air- plane that crashed on take-off would probably result in such spills. Hydrogen's wide range of flammability and low ignition energy is offset by its great tendency to disperse from the scene of a leak or a spill because of its buoyancy and high rate of diffusion (refer to Fig- ure 8-1). An accident in which a tank truck full of liquid hydrogen rolled over with no resulting fire and no harm to the driver is some- times cited in the literature.11 The hydrogen evaporated and dispersed quickly upwards from the crashed truck. Because there have been few accidents to date, *the statistics of hydrogen tank truck accidents are too poor to stress this evidence. No doubt the statistics of gasoline tank truck accidents also contain reports of comparable harmless events; they also contain reports of truly devastating events. In contrast with hydrogen, when gasoline is spilled, vapors heavier than air spread in a wide layer near the ground. This greatly increases the hazardous area. Thus the tendency of hydrogen to disperse much more rapidly than other fuels, even gaseous methane, is a large point in its favor. Metal hydrides offer certain safety advantages over liquid or gase- ous storage and distribution of hydrogen because heat must be supplied to expel hydrogen from the metal hydride. Consequently, metal hydrides cannot leak to any appreciable extent (only a tiny amount randomly dif- fusing out of the hydride). If used as a fuel tank in an automobile, for example, an accident could not directly cause release of hydrogen. However, should a fire start for other reasons and heat the hydride sufficiently, then hydrogen would be released to add to the fire. De- pending upon the actual metal hydride involved and the specifics of the situation, the release could be self-sustaining or could be self- extinguishing because of a deficiency of heat. However, since powdered 135 PAGENO="0415" 409 metals often burn (especially magnesium, which is pyrophoric), the metal carrier may itself pose a hazard. D. Experience in the Space Program and the Hindenburg Frequent reference is made to the excellent safety record maintained by NASA in its use of vast quantities of liquid hydrogen used in the U.S. space program''3'4"'4 Unfortunately, this excellent record should not be extrapolated to the large-scale use of liquid hydrogen by the general populace because of several important differences: * NASA personnel handling hydrogen are specially chosen and trained.14 * Hydrogen use in the space program has been restricted to rigorously controlled out-of-doors environments. * Extreme concern about the reliability of systems has dominated the entire space program thereby minimizing the chance of acci- dental release of hydrogen. * Hydrogen safety procedures to protect both personnel and expen- sive, often unique, hardware have received major emphasis. Undoubtedly the NASA experience offers encouragement about the safe use of liquid hydrogen and should serve as a point of departure for the development of more generally applicable future hydrogen safety proce- dures.11 Nevertheless, the NASA experience is simply inadequate to serve as a basis for decision-making concerning more general aspects of a hydrogen economy in which the substance would be generally in unskilled hands. An informal club called the H2indenburg Society has arisen among the fraternity of people who advocate the hydrogen economy. These people believe that the general public associates hydrogen with the disaster in which the dirigible Hindenburg was destroyed by fire at Lakehurst, New Jersey, in 1937; they call this association the "Hinden burg Syndrome. Although they were designed to use helium for buoyancy, 136 PAGENO="0416" 410 the large Germany airships of the 1930s were filled with gaseous hydro- gen because the United States would not sell helium to Germany.''15 The Hindenburg, violating safety rules, approached Lakehurst through a thunder- storm and caught fire and burned while attempting to dock.1'15 A large technologically related disaster for its time, the Hindenburg accident* killed 36 passengers and 22 crewmen,16 but it is usually forgotten that 65 people on board survived.1 The number of people killed in the Hinden- burg is small compared with the number killed in crashes of modern wide- body aircraft. The importance of the Hindenburg accident to the hydrogen economy lies less in what it reveals about the actual safety of hydrogen than in what writers, journalists, and movie makers attempt to make of it. The authors question whether the general public really does associate the hazard of hydrogen with the Hindenburg. Instead, we suspect that this association is common mainly among people with technical training because they are most apt to recall their experiments in high school or college chemistry courses. However, the release of the movie Hindenburg (scheduled for late l975),'~ may seriously distort public attitudes. E. Special Hazards Two special hazards associated with hydrogen are not as widely known as its flammability. One is the extreme cold of liquid hydrogen, which can damage severely or kill living tissue. The other is hydrogen embrittlement of materials, which can cause storage, distribution, and utilization facilities/devices to fail. *Publicists little note the successful career of the hydrogen-filled Graf Zeppelin, which made regular and safe crossings of the Atlantic from 1928 until her retirement in 1937. 137 PAGENO="0417" 411 Since contact with an extremely cold substance produces a sensation much like that of a heat burn, wounds inflicted by cold substances are also called burns.' The likelihood of liquid hydrogen spilling and splashing on many people to cause such burns is relatively small because of hydrogen's rapid rate of evaporation. Only in a massive spill, in which the environment was so depleted of heat energy that evaporation was impeded, would there be the likelihood that people would come into intimate contact with the liquid. However, damage to living tissue could also result from contact with the greatly chilled objects or air surrounding a spill. Experience with cryogenic liquids is still rare and the hazards are not yet appreciated.by the general public. Hydrogen environment embrittlement (see Chapter 6) can cause hydro- gen storage, distribution, or utilization devices to fail.171~ thereby releasing hydrogen, which might ignite and burn. In addition, the fail- ure of a mechanical part could cause an accident that might have conse- quences even more serious than a hydrogen fire or explosion. Because hydrogen environment embrittlement is most pronounced in high-strength steels exposed to high-pressure, high-purity hydrogen near room tempera- tures,'71~ many hydrogen-related activities, such as liquid handling, would be immune from embrittlement. Nevertheless, it is now generally recognized that a crucial part of guaranteeing occupational and public safety in the face of hydrogen usage will be careful evaluation of the materials at relevant values of temperature, pressure, and hydrogen purity. It is generally believed that engineering solutions can be found to assure a reasonable degree of safety.18 It might be found, however, that certain geophysical hazards make hydrogen environment embrittlement more dangerous in some areas than in others. In particu- lar, large hydrogen gas pipelines traversing seismically active areas-- such as California or Alaska--might prove especially dangerous. 138 62-332 0 - 76 - 27 PAGENO="0418" 412 F. Summary of Physical and Chemical Aspects of Safety There are too many compensating aspects of the physics and chemistry of hydrogen to make blanket statements about its actual safety. Instead, the safety question must be addressed and answered on a situation-by- situation basis. In each case, the important parameters that affect the outcome of the evaluation include: * The geometry and degree of confinement of the environment in which the hazards exist. * The proximity, number, strength, and duration of ignition sources. * The temperature, pressure, and purity of the hydrogen and the nature of the materials exposed to it. * The intelligence, experience, training, skill, and regimenta- tion of people exposed to the hazards. * Consideration of failure events, as well as routine circum- stances. G. Perceptions of Safety Hazards - A Key to Policy Public perceptions of the safety of hydrogen may be one of the major obstacles to a transition to a hydrogen economy. A key to policy making lies in recognition of the distinction between two different types of perceptions and their implications: familiarity with "real" hazards as opposed to "nonreal" or imagined hazards. Decision-makers in both the public and private sectors must take into account both types of perceptions. Perceptions of "real" hazards usually have their basis in familiar- ity with technical facts derived from physics, chemistry, and the condi- tions of the environment of exposure. Certainly, many "real" hazards exist in the utilization of hydrogen, but these hazards are not abso- lute; instead, they are relative to the specific conditions of use. 139 PAGENO="0419" 413 Perceptions of `nonreal" hazards are based on incomplete knowledge and can be further influenced by many factors. Although there are many different theories on attitudes and attitude formation, each arising from different psychological theories of personality, it is generally recognized in most theories that attitudes are based in part on "be- liefs." A person's beliefs are affected by a seemingly endless list of factors including experience, education, age, income, sex, geographic location, ethnic group, religion, and exposure to news media. Since the actual safety of hydrogen is so variable and so dependent on the specific conditions of its use, the factor of education seems to be especially important. A fairly high level of knowledge about the technology would be required to understand all the relevant qualifying conditions. Individuals with the power and responsibility to make decisions generally have access to technical information superior to that tradi- tionally available to the general public. Since comprehensible techni- cal information has generally been lacking, the public has been forced to rely on the downward trickle of bits and pieces of information, many of which are easily misunderstood. This information frequently contains *inconsistencies or contraditions, particularly in "grey" areas where there is disagreement among experts. Three factors seem especially relevant in the conditioning of the public's perceptions about the safety of hydrogen. * The newness of many aspects of the technology. * The usual lack of understandable technical information for the general public. * The apparently contradictory experience and statements about hydrogen safety. The combination of these three factors could easily create an atmosphere within which the public would be opposed to hydrogen, especially since there will be a tendency to publicize mainly the hazardous aspects. As 140 PAGENO="0420" 414 a result, the public is not likely to base its perceptions of hydrogen safety on a "real" basis. This problem is confounded by the long period of transition to the hydrogen economy during which there is a turnover in the population comprising the public. Decision-makers will have to respond to public attitudes no matter what type of information lies behind them. In particular, it would matter little whether negative attitudes towards hydrogen were based on "real" or "nonreal" perceptions of hazards: Both could have the same impact on the ultimate acceptance or rejection of the hydrogen economy. The increase in both the number and size of citizen action groups over the past decade indicates heightened public interest in environmen- tal and consumer affairs. These groups have increasingly been able to influence legislation and corporate decisions. Unless public apathy sets in before the hydrogen economy begins to emerge, it will be crucial to obtain general acceptance prior to implementation of major hydrogen f a- cilities. If acceptance fails to develop, attempts to block or modify implementation should be expected. H. Voluntary vs Involuntary Exposure to Hazards Exposure to hydrogen will be involuntary once a transition to a hydrogen economy begins, Consequently, pressures for stringent regula- tion regarding hydrogen use can be expected to develop. Voluntary exposure to hazards results from individual choice. The most clear-cut examples of voluntary exposure are found in recreational activities: skiing, auto racing, scuba diving, playing football, etc. Before participating in these activities the individual has generally decided that the risk is acceptable compared to the rewards. However, involuntary exposure to hazards occurs when the decision is beyond an individual's reasonable control. Natural conditions that create 141 PAGENO="0421" 415 involuntary exposure include: hurricanes, earthquakes, floods, and tornados. The technology of modern civilization also creates involun- tary exposure to .such hazards as air pollution, water pollution, gaso- line tank trucks on the highways, and airplanes flying overhead. Tech- nologically induced involuntary exposure to hazards are the results of governmental or corporate decisions beyond individual control. Recent years have seen a trend towards increasingly broad and stringent regulation of activities which create involuntary exposure to hazards. The increased governmental regulation in safety devices, and food and drug testing areas are examples of this trend. The combination of the likely misconceptions about hydrogen safety and involuntary ex- posure are likely to result in tough new restrictions upon hydrogen technologies. This control may even be more restrictive than has been applied to other fuels or energy technologies, merely because the hydro- gen economy is starting free of established major pro-hydrogen interests, but with a large number of interests that stand to lose if hydrogen use becomes established. Thus, ironically, because stringent regulations can lead to safe technology and practice, the hydrogen economy could conceivably prove to be safer than the existing state of affairs. 142 PAGENO="0422" 416 REFERENCES 1. D. P. Gregory et al., "A Hydrogen-Energy System," American Gas Association, Alexandria, Virginia (August 1972). 2. W. F. Stewart and F.J. Edeskuty, "Logistics, Economics, and Safety of a Liquid Hydrogen System for Automotive Transportation,' pre- sented at the Intersociety Conference on Transportation, Denver, Colorado, 23-27 September 1973. American Society of Mechanical Engineers Publication 73-ICT-78. 3. L. T. Blank et al., "A Hydrogen Energy Carrier," Systems Design Institute, National Aeronautics and Space Administration-American Society for Engineering Education, Johnson Space Center, Houston, Texas (1973). 4. "Hydrogen and Other Synthetic Fuels," a summary of the work of the Synthetic Fuels Panel, prepared for the Federal Council on Science and Technology R&D Goals Study (September 1972). 5. H. G. Zabetakis and D. S. Burgess, "Research on the Hazards Associ- ated with the Production and Handling of Liquid Hydrogen," Bureau of Mines (1961). 6. Mr. Thomas Goodale, Poulter Laboratories, Stanford Research Insti- tute, Menlo Park, California (personal communication). 7. Chelton, D. B., "Safety in the Use of Liquid Hydrogen," in Tech- nology and Uses of Liquid Hydrogen, R. B. Scott, W. H. Denton and C. H. Nicholls, eds. (The Macmillan Company, New York, 1964), pp. 359-378. 8. L. H. Cassutt, F. E. Haddocks and W. A. Sawyer, "A Study of the Hazards in the Storage and Handling of Liquid Hydrogen," in Advances in Cryogenic Engineering, Vol. 5 (Plenum Press, New York, 1960), pp. 50-61. 9. Mr. Erwin Capener, formerly of Stanford Research Institute, Menlo Park, California (personal communication). 143 PAGENO="0423" 417 10. "When Gas Pipelines Blow Up," Business Week (4 August 1973), p. 50. 11. P. M. Ordin, "A Review of Hydrogen Accidents and Incidents in NASA Operations," 9th Intersociety Energy Conversion Engineering Con- ference, 1974, pp. 442-453. 12. F. A. Martin, "The Safe Distribution and Handling of Hydrogen for Commercial Application," 7th Intersociety Energy Conversion Engi- neering Conference, 1972, pp. 1335-1341. 13. J. R. Bartlit, F. J. Edeskuty, and K. D. Williamson, Jr., "Experi- ence in Handling, Transport, and Storage of Liquid Hydrogen--The Recyclable Fuel," 7th Intersociety Energy Conversion Engineering Conference, 1972, pp. 1312-1315. 14. "Hydrogen Safety Manual," by the Advisory Panel on Experimental Fluids and Gases, National Aeronautics and Space Administration, Lewis Research Center, Cleveland, Ohio, NASA Technical Memorandum TM X-52454. 15. J. Toland, The Great Dirigibles--Their Triumphs and Disasters, revised edition (Dover Publications, New York). 16. "Hindenburg' Dirigible Will Fly Again (but only on silver screen)," Palo Alto Times (23 August 1974), p. 14 (Associated Press). 17. A. W. Thompson, "Structural Materials Use in a Hydrogen Economy," paper 37c, presented at the annual meeting of the American Insti- tute of Chemical Engineers, Washington, D.C., 3 December 1974. 18. R. P. Jewett et al., "Hydrogen Environment Embrittlement of Metals," National Aeronautics and Space Administration Report CR-2l63 (March 1973). 19. H. H. Johnson and A. J. Kumnick, "Hydrogen and the Structural Inte- grity of Alloys," in Hydrogen Energy, T. N. Veziroglu, ed. (Plenum Press, New York, 1975), pp. 1043-1056. 144 PAGENO="0424" 418 SECTION VII CONSEQUENCES OF A HYDROGEN ECONOMY Hydrogen could be used in essentially every application requiring energy and in some chemical applications as well. The societal implica- tions of such uses, however, vary widely in their gravity. This section focuses on four areas judged to have the largest, most widely distributed potential consequences: automotive, aviation, utilities, and steel- making and ammonia synthesis. 221 PAGENO="0425" 419 CHAPTER 14--IMPACTS OF HYDROGEN-FUELED PRIVATE AND FLEET AUTOMOTIVE VEHICLES A. Private Automobile 1. The System and the Stakeholders Privately owned automobiles are but one part of a complex sys- tem of automotive transportation. The complete system consists of * Vehicles * Fuel producers, distributors, and retailers * Vehicle manufactures and sales outlets * Vehicle maintenance and repair facilities * Roadways. The last four items can be viewed as supporting or infrastructure net- works, and, as far as hydrogen is concerned, the most critical is the fuel logistics network. Except for roadways, this is the network with which the vehicle owner must most often interact, and, as a consequence, the outlets for this network have become very much more widespread than the elements of the other infrastructure networks.* It is characteristic of many networks that once they are widely deployed, their standaids become fixed and they become resistant to change and, therefore, extremely difficult to supplant. To a very real extent, networks become the dominant aspect of systems, and the concerted effort and expense needed to make even minor changes serve to deflect *Although many fuel filling stations also offer some maintenance and repair service. 222 PAGENO="0426" 420 many conceivable improvements. There are many examples of institution- alized networks that seemingly will impose their standards on U.S. so- ciety indefinitely such as the gauge (separation) of railroad tracks, the 60-Hz, 115-volt electrical system, the transmission standards of broadcast television, and the bandwidth of telephone circuits. For better or for worse, these networks and their standards evolved and became established at a time when there was no competitor or even near competitor to the system they represent. Yet, once establishedand widely used, they exert a practical limit on future possibilities. A system of automobiles equipped with either liquid hydrogen or metal hydride fuel-storage is simple to imagine but the supporting fuel distribution network implied is quite different from the present gaso- line logistics network and by no means represents a small evolutionary change of the existing gasoline network. Rather, hydrogen would require a completely different system, and a transition from our present gaso- line system to a hydrogen system would, therefore, require an enormous degree of effort, expense, and coordination. Indeed, so large are these inhibiting factors that the fuel logistics network is probably the single *most important barrier to the realization of a hydrogen-fueled automotive system. This assertion deserves further examination because the prin- ciples involved are also applicable to the potential changeover to hydro- gen in other energy-using systems considered elsewhere in this report. To the consumer, a vehicle is, first of all, a source of personal mobility. Any change in the automotive system that would detract from his accustomed or expected freedom of mobility would diminish the at- tractiveness of owning a car. If, for example, the fuel stations were to become less numerous and farther apart, or if the availability of his particular fuel were reduced, then the owner's convenience would also be reduced and along with it his satisfaction with car ownership. Two examples illustrate this point. 223 PAGENO="0427" 421 First, diesel-powered cars have long been available (although at a higher price than the equivalent gasoline-powered car), but sales have never been large.' The low sales probably stem largely from the consumer's reluctance to commit himself to dependence on the diesel fuel network,* which is substantially more sparse (mainly truck stops or marinas) than the nearly ubiquitous gasoline network. Consumers have shown preference for gasoline-powered cars, even though diesel cars both get better mileage and usually have larger fuel tanks (thereby increas- ing the range between refueling). Second, the recent introduction of standards to tighten auto- mobile air pollutant emissions has led to the use of catalytic conver- ters to clean carbon monoxide and hydrocarbons from car exhaust. Un- fortunately, the lead-containing chemical compounds routinely added to most gasolines to improve their octane rating (and thus the smoothness of combustion) rather quickly poison the platinum catalysts in these converters rendering them useless after as little as two tanks of leaded fuel. Consequently, the EPA mandated that lead-free fuel be made avail- able nationwide to protect the converters from degradation.2 To achieve the assurance of an adequate availability of lead-free fuel involved considerable negotiations over a period of several years between EPA and the fuel suppliers concerning the rules defining how many and which gaso- line filling stations would be required to carry the lead-free fuel.2 *Some will argue that the sluggish performance of diesel-powered cars compared to gasoline powered cars is the "real" reason diesel cars have not been popular. We acknowledge this contribution, but doubt that this is the main reason and point to the many gasoline powered vehicles, such as the Volkswagen buses, which also exhibit poor performance but nevertheless have sold well. 224 PAGENO="0428" 422 Meanwhile, individual consumers and automotive interest groups (such as the American Automobile Association) expressed concern about the availability of lead-free fuel in rural areas and in Canada and Mexico, while automobile manufacturers worried that these consumer con- cerns about fuel availability would lead to low sales of the new catalyst-equipped cars. Without question, the complexity of the change implied by a transition to hydrogen far exceeds the recent partial change to lead-free gasoline, and although the lead-free gasoline issue has now been resolved successfully the degree of controversy engendered indicates what may be expected should a change to hydrogen begin to take form. Because of the kinds of problems indicated above, it generally proves far simpler to change the nature of the vehicle that interacts with an unchanged fuel system than to change the fuel system itself. A good example of this is the way Mazda was able to introduce the Wankel, or rotary, engine. Because the buyer mobility and refueling habits were not threatened, little resistance to engine innovation arose.* Far more radical engine changes could be readily accomplished as long as the en- gines use the same fuel and thus do not threaten to impair the consumers' mobility. Consumers, of course, are not the only parties with a stake in a transition in the fuel network. Fuel vendors have a financial stake that far exceeds that of the individual consumer. There are basically three classes of gasoline station operations: *The consumer did have to be concerned about the adequacy of the repair and maintenance network, but since he usually interacts with this net- work far less frequently than with the fuel network, his concern was less acute. 225 PAGENO="0429" 423 * Owned by the oil companies whose product is sold. * Independently owned station franchised by the oil companies whose brand is sold. * Independent stations that purchase wholesale from several producers. Since the first two classes are by far the dominant business forms dis- pensing gasoline to the public, it is basically the decisions of the major oil corporations rather than the station operator that determine the fuel to be sold. As long as the major oil companies perceive that they can con- tinue to supply gasoline in basically the quantities desired by consumers, they naturally have very little interest in embarking on a transition to hydrogen. Even when they begin to question their capability of sus- taining supplies from conventional (natural) crude oil from either domes- tic or foreign sources they can be expected to first turn their attention to synthetic crude oils derived from oil shale and coal.3a These syn- thetics hold several attractions to the existing major oil companies not offered by hydrogen. First, synthetic crudes can be blended with con- .ventional crudes thereby protecting existing investments in facilities for transportation, refining, and marketing from premature obsolescence.3'5 Second, companies, as do the individual people that comprise them, tend to prefer to do those things that are familiar. As a result, slowly transforming the business from dependence on conventional sources of oil to synthetic oils is a far more comfortable prospect than blazing a trail to hydrogen.5 Moreover, with an uncertain market for hydrogen but a certain market for gasoline, the major oil companies have shown (and will likely continue to show) very little interest in the hydrogen- fueled automobiles. It is conceivable, of course, that an aggressive company pres- ently outside the automotive fuels market might decide to offer hydrogen 226 PAGENO="0430" 424 through a special chain of fuel outlets in competition with gasoline. Probably the most appropriate corporate interests here are large chemi- cal companies (as evidenced by Union Carbide's interest in hydrogen) because of their large resources and technical know-how. The success of this conceivable course is unlikely, however, because it would in- volve vigorous competition between products and companies rather than merely a gentle competition between products (such as gasoline and diesel) of the same company. The high cost of marketing would be to the great disadvantage to the newcomer because of the uneven match of assets and automotive marketing wherewithal of the rival companies.~ Automobile makers also would have a large stake in any future hydrogen automobile system and would naturally be concerned whether con- sumers would buy a hydrogen-fueled automobile and whether fuel would be available. All the concerns mentioned above about the no-lead gaso- line experience would apply, but in heightened form. In addition, auto- mobile makers would be concerned that the small initial production runs of hydrogen-powered cars would make it difficult to reap economies of scale and thus would either mean low profits on hydrogen cars or else -mean sales at noncompetitive prices. 2. The Dilemma Because neither the fuel producer, the auto maker, nor the consumer, is especially eager to take the first risky step, a transition to a hydrogen-fueled automotive system poses a kind of three-way dilemma similar to that posed by the query of whether the chicken or the egg came first. This is a true dilemma that can be seen to greatly stifle a free market evolution from a gasoline-based to a hydrogen-based auto- motive system. It is natural to ask, then, how the present automotive system evolved and how its strong, and presently confining, inertia became established in the first place. 227 - PAGENO="0431" 425 Historically, the automotive system--both vehicles and fuel-- evolved together from a base of zero.1 Indeed, the strong market inter- dependence between the auto makers and the oil companies is traceable to their simultaneous and symbiotic growth. When both started, there were many highly competitive auto-making and oil companies involved, but business failures and consolidations led both the vehicle and fuel pro- duction aspects of the automotive system to become far more concentrated and oligopolistic. The horse-powered transportation mode that gasoline- powered automobiles displaced was likewise fragmented with no meaningful consolidation of market power in wagon makers, horse breeders, or hay sellers. Moreover, because the automobile competitively offered an jncrease in sustainable speed that the horse could not offer, the trans- portation modes were differentiated in quality and not really equiv- alent. Moreover, there is an important asymmetry in the three-way dilemma: In the vehicle manufacturing and fuel marketing sides of the triangle the decision-making is relatively concentrated in a few indi- viduals, but on the consumer side the decision-making is highly dis- persed. In particular, while the decision to make a hydrogen-fueled vehicle resides in the president or board of directors of major auto- mobile makers and the decision to produce the fuel similarly lies in the upper echelons of energy company executives, in a free market the decision whether and when to buy a hydrogen-fueled car would reside with literally millions of individual consumers. For exactly this reason, without governmental forcing of the issue, the prospect for hydrogen-fueled fleet vehicles is far greater than for personal ve- hicles. Accordingly, the transition scenarios of Chapter 13 showed the advent of hydrogen-powered fleet vehicles considerably earlier than that of personal vehicles. 228 PAGENO="0432" 426 3. Transition Strategies The considerations discussed above are general and would be most acutely felt if a transition to hydrogen-fueled vehicles were to occur simultaneously throughout the nation. Coordinated decision-making between vehicle makers and fuel suppliers would be essential and would almost certainly have to follow the use of hydrogen in other sectors, both to facilitate fuel distribution and also to provide valid experi- ence on which consumer reaction to hydrogen could be based. In a nationwide program, the fuel suppliers' strategy would probably be to provide hydrogen at only a few centrally placed locations within metropolitan regions and await an increased number of vehicles before opening additional fueling stations. Consumer inconvenience in dealing with only a limited number of fueling points would surely impede vehicle sales for an indefinite period, but if momentum could once be established, then the transition would tend to be self-reinforcing be- cause more vehicles would justify more fuel stations, which would lead to more vehicles, and so on. Indeed, at some point there would be a crossover at which the diminished number of gasoline powered cars would, in turn, have so reduced the number of gasoline stations that hydrogen rather than gasoline would become the more attractive fuel to consumers. There is the implication, however, that midway through the transition, neither fuel network would be as extensive as people now experience, and thus there would be a temporary reduction in the net convenience of both forms of personal automotive travel.* The major problem, of course, is how the transition process could be begun and sustained (if the mechanism *During this era people might shift increasingly to public forms of transit. 229 PAGENO="0433" 427 of transition were easy, the diesel-powered car might already have taken over). It is sometimes suggested that hydrogen-powered vehicles might be introduced by mandate in a relatively small region, which has severe air pollution, as a means to improve air quality. Neglecting the com- plex political question of whether such a mandate could ever become feasible in a democratic U.S. society, this approach would greatly off- set the inherent difficulties of transition. In particular, because the number of hydrogen-powered vehicles in the region would grow quickly, the deployment of fueling stations would proceed quickly, thereby allevi- ating consumer inconvenience. While this would improve flexibility of travel within the region, the usefulness of the hydrogen-powered car might very well be limited to the mandated region. Perhaps expanded and subsidized use of gasoline-powered rental cars would provide an acceptable mechanism for travel outside the mandated region whenever necessary. Travel into the restricted region by migrants and tourists and a residual population of aged gasoline-powered cars would require either the indefinite maintenance of a skeletal gasoline distribution network or the use of rental hydrogen powered cars by visitors. 4. Air Quality Implications A complete transition to hydrogen powered automobiles would have an enormous impact on urban air quality because the automobile is the dominant source of air pollutants in most cities. However, as suggested in the transition scenarios of Chapter 13, the time for auto- motive transition is distant and the transition would proceed slowly. Accordingly, improved air quality could only be realized slowly. Even if the transition were to be mandated tomorrow and were to proceed as quickly as new cars could be built, the period of transition would last for more 230 62-332 0 - 76 - 28 PAGENO="0434" 428 than ten years because the annual turnover in vehicles runs about 10 percent per year.7 The clean air benefits of hydrogen-powered cars has received considerable attention from researchers,813 hobbyists, 14,15 and the press.152° Figure 14-1 shows a widely quoted test result (obtained on a small specially adapted engine) that reports nitrogen oxide emissions considerably below those for gasoline.13* Such low levels of nitrogen oxide emissions are not universally reported, however. Figure 14-2, for example, shows that at power output levels suitable for automotive propulsion, the nitrogen oxides from hydrogen and gasoline are similar.21 Because nitrogen oxide formation is mainly related to the peak tempera- tures achieved during combustion, there is apparently no intrinsic advan- tage in a hydrogen-air engine with regard to these emissions.t There is presently debate among hydrogen engine researchers concerning the level of intrinsic nitrogen oxide formation and approaches to avoid its for- mation.22 Although hydrogen-powered cars might prove to be nearly pollution-free, the building block analysis of Chapter 12 shows that considerable industrial activity would occur where the hydrogen was generated. Therefore, because of this behind-the-scenes industrial activity, the locus of pollutant emissions would be transferred from streets and roads to hydrogen-generating plants elsewhere. Although these would probably emit less total pollution (by some measure) *Since hydrogen contains neither carbon nor hydrocarbons these pollu- tants would not be expected. This is the theoretical basis for the attraction of hydrogen as a motor fuel. However, trace levels to sub- stantial amounts of these emissions can derive from the consumption of lubricating oil. tA hydrogen-oxygen engine could not produce nitrogen oxides. 231 PAGENO="0435" RELATIVE TO BHP Hydrogen * `~ TT-~ 40 60 80 100 120 140 160 180 200 220 240 SOURCE: Refirence 3 PERCENT OF STOICHIOMETRIC FUEL FIGURE 14-I. NITROGEN OXIDE (NO0) EMISSION FROM A SMALL ENGINE AS A FUNCTION OF FUEL TYPE 100. U 10.0 6 1.0 U) 0 U) U, w 0 z 0.01 0.001 I 1 I I ,2 X-X-D p_ ~~x-0 - 1977 EPA STANDARD X ~ (0.4 gmlmi) X - I I I I I LU ~ ~ ~1 < LEAN~ 0 I ~ ~- ~ < LU -J I . ~RlCH - xHYDROGEN DATA OGASOLINE DATA - I I 1 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 .1 1.2 1.3 1 .~ EQUIVALENCE RATIO SOURCE: Reference 2) FIGURE 14-2. NITROGEN OXIDE (NO0) EMISSION FROM A HYDROGEN-FUELED AUTOMOBILE ENGINE COMPARED TO SAME ENGINE FUELED WITH GASOLINE (Hatched area corresponds to power levels suitable for outomolive propulsion) 429 Gasoline NO0 EMISSIONS lOO0/~ THROTTLE TO IHP 20 16 12 z 0 5)8 11) w 232 PAGENO="0436" 430 than corresponding travel in gasoline-powered automobiles, the pollu- tants may be entirely different species. For example, if hydrogen were generated either electrolytically or thermochemically from a primary energy source, the net effect would be to exchange carbon monoxide and hydrocarbon emissions for nuclear power thermal discharges into bodies of water or air used to cool the reactor, low-level radioactive emis- sions,23 the generation of radioactive waste, and the threat of theft of dangerous materials24 (such as plutonium). These problems of nuclear energy being used for hydrogen production provide strong arguments in favor of solar energy technologies being used instead. To illustrate, automobile registration in California was about 11 million cars in 1973. To produce enough hydrogen to power these ve- hicles would require hydrogen generation as shown in Table 14-1. Table 14-1 HYDROGEN GENERATION NEEDED TO SUPPLY 1973 CALIFoRNIA AUTOMOBILE DEMAND Number of Building Block Sized Plants* at Motor Thermal Efficiency Equal to Gasoline Enhancedt Coal gasification 21 16 Nuclear fission/electrolysis 58 44 *See Table 12-1 for plant building block size and output. tSee Figure 7-7. 233 PAGENO="0437" 431 Where that many nuclear/hydrogen generating plants (for example) might be located is open to question. The coal gasification plants would be located most economically near the coal resources, and thus California's (for example) automotive air pollution could be averted at the expense of creating air pollution in coal resource regions (e.g., Wyoming's Powder River Basin). Table 14-2 shows a comparison of the pollutants saved (at the vehicle) and the pollutants created (at a coal gasifica- tion plant) with well controlled emissions.5 The political implications of this transfer are significant and some states, most notably Montana, are already developing policies to the effect that coal mining in the state may be acceptable but that coal conversion probably will not be acceptable within the state.5 These state policies are a result of issues that run deeper than the issue of air pollution. For example, coal gasification facilities consume vast quantities of water (about 8200 acre feet per year for 250 million cubic feet per day) and the western coal-rich regions are water poor.a Even if the most extreme consequences of this were to result--namely that coal would be brought to California for gasification--the air pollution in urban areas should decrease because pollution can be controlled more readily in a few large plants than in millions of individual vehicles. B. Social Impacts 1. Derived from Safety Considerations Increased exposure to the safety hazards characteristic of hydrogen is one of the major social impacts that would result from the u~e of a hydrogen automobile. Although, like many commonplace things, hydrogen is a hazardous substance, as discussed in Chapter 8, the hazard to people is not absolute but is relative to the conditions of hydrogen in actual use. Although gasoline is also a hazardous substance, society has clearly decided that the benefits of its use outweigh its hazards. 234 PAGENO="0438" Table 14-2 COMPARISON OF EMISSIONS OF AIR POLLUTANTS IN GASOLINE-POWERED CARS, PETROLEUM REFINERIES, AND HYDROGEN PRODUCTION PLANTS (All qnantItie~ In grams/mile'1 Carbon Nitrogen Sulfur Monoxide Hydrocarbons Oxides Particulates Oxides Gasoline system Vehicle' 14 1.6~ 2.2 0.386 0.20 Refinery2 0.045 0.075 0.037 0.006 0.08 Total 14 1.7 2.2 0.39 0.3 hydrogen from coal gasification3 Lurgl 0.2 <<1 0.3 Synthane 0.03 2 0.2 0.5 Hygas 0.03 1 0.1 0.6 Typical 0.03 1 ~0.l 0.5 1Refcrence 25. Vehicle emissions arc those estimated for the year 1990. however, recent plans to delay (see Reference 26) implementation of stricter standards may cause these numbers to be underestimates. 2Uslng average emission factors for the Los Angeles area refineries (which have the lowest California refinery emissions) and assuming 20 miles per gallon for automobiles. (Reference 27.) 3No factors are available for a plant making hydrogen from coal. Consequently, emissions for a plant making methane from coal have been used. This should be a good approximation because the emissions from the CO shift reactions needed to produce hydrogen (but not methane) should roughly offset the emissions from the methanation reaction. 4fleference 28. Excludes crankcase and evaporation. Excludes tire wear. PAGENO="0439" 433 Table 8-1 compared the safety-related properties of hydrogen, gasoline, and other possible fuels. If stringent safety related regulations are both promulgated and followed in the design, production, and use of hydrogen-fueled automobiles, there is a good possibility that the actual safety hazards could be no worse (but different in kind) than those ac- cepted in gasoline-fueled automobiles. However, it also seems likely that, at least initially, individual citizens will not perceive hydrogen to be as safe as gasoline. Society as a whole will have a special interest in the possible dangers presented by a hydrogen-fueled automobile because exposure will be involuntary once a transiton begins. Drivers (even of gasoline- powered cars), passengers, and even persons passing by on the streets will be increasingly exposed to hydrogen. State highway patrols, police, firemen, rescue teams, and ambulance attendants must be suitably pre- pared for whatever actual dangers are presented by hydrogen. Individuals within these emergency service groups will require specialized training to deal with the new hazards posed by hydrogen. However, since all of these groups normally undergo specialized training, this should not cause a major impact. Individual perceptions of the safety hazards of a hydrogen- fueled automobile may be very different from the hazards that actually exist and therefore individual concern over the safety hazards may as- sume the appearance of being exaggerated and unrealistic. As discussed in Chapter 8, perceptions of nonreal hazards are usually based on in- complete or erroneous knowledge and can also be influenced by sociologi- cal and psychological factors. Because of a general lack of understand- able technical information for public consumption, coupled with con- flicting statements, it seems likely that people will mainly view the safety hazards of a hydrogen car on a nonreal basis with a consequent resistance to a hydrogen-fueled automobile. If a transition were to 236 PAGENO="0440" 434 begin before public acceptance of the hydrogen technology has occurred in less personally threatening spheres (for example, in electric utility load leveling) extreme social impact might result from organized attempts to block or otherwise counter implementation. Actual safety hazards of a hydrogen-fueled car that must be considered include liquid storage tank ruptures, fuel system malfunc- tions, vehicle breakdown, and collisions. The most commonly expressed concern regarding hydrogen involves fires or explosions following rupture of a storage tank and fuel spill (even though explosions are exceedingly unlikely). Although less energy is required to ignite hydrogen than gasoline, the ignition temperature required is higher. However, it has been stated in the literature that while a spark or open flame could ignite hydrogen, a lighted cigarette could not.29 Some have asserted that the safety hazards of refueling a hydrogen-fueled automobile would be less than those presented by gaso- line refueling29 because concern with safety and the desire to conserve the boil-off gas would lead to use of a "closed" fueling system. By contrast, a gasoline transfer system is "open," and allows the poten- tially hazardous (and readily seen) vapors to escape to the atmosphere. Since this assertion is quite reasonable, probably the greatest hazards with hydrogen cars, as in gasoline-powered cars, will come from un- controlled collisions. In a collision, there would likely be sparks generated by the impact, the bending and tearing of metal, and the scraping of vehicle parts on the pavement. If spilled hydrogen did not ignite, its high buoyancy and diffusity would lead it to dissipate upwards from the scene very rapidly; in contrast, gasoline spills give off vapors that are heavier than air and that spread at ground level. If the hydrogen alone were to ignite, its low amount of radiant energy would keep the 237 PAGENO="0441" 435 fire from spreading through the mechanism of heating and igniting nearby objects, but the nonluminous character of hydrogen flame would make it easier for a person to inadvertently contact it. However, if there were a fire, it is highly unlikely that other objects nearby would escape being ignited. Thus, a hydrogen fire resulting from a collision would still be cause for concern. Metal hydride storage tanks pose a differ- ent kind of hazard; while little hydrogen can escape from an unheated ruptured container, the metal hydride powder of some suitable alloys (especially magnesium) can itself ignite and burn. Special hazards may arise during the transition period when both hydrogen- and gasoline-fueled cars are on the road. A collision involving both types of vehicles might create an especially difficult fire control situation because a quickly burning hydrogen fire might start a longer, even more hazardous gasoline fire. 2. Specialization Required in Production and Maintenance Actual production of the hydrogen fuel distribution and on- board systems will require more precision than is necessary for a gaso- line system because of the exactness required to insure leakproof sys- tems for safety reasons. As a result, some factory workers will need more skills than they need today; similarly, automotive mechanics will require specialized training to detect and rectify problems with hydro- gen fuel systems. It is difficult to gauge the magnitude of these im- pacts at this time because the degrees of specialization required and the overall educational attainments of the population at the time when a transition might begin are difficult to foresee. Regardless of mag- nitude, most individuals affected will be blue collar workers. 238 PAGENO="0442" 436 3. Decreased Independence and Self-Reliance The specialization required to repair the hydrogen fuel system and the dangers posed by a leaky system, would probably mean that hydro- gen car owners would be more dependent on mechanics for repair work than they are with gasoline-powered cars today. This would affect all hydro- gen car owners to some extent, but especially those who prefer to perform some of their own auto repairs. A number of men customarily have performed their own auto re- pairs and thereby have both decreased the cost of repair work and demon- strated independence and self-reliance. Many men have taken pride in the mechanical condition of their automobiles, particularly those who have had the mechanical ability to keep their cars in good running con- dition. Men have been able to exhibit a certain amount of masculine "power" over the world by means of self-repair of cars. Such individual demonstrations of power seem to be gaining importance as the world be- comes increasingly specialized, computerized, and bureaucratic. The new feminism of the past few years has begun to challenge the "male only" tradition of mechanical ability. Women are becoming more independent and self-reliant in areas that have traditionally been left to men. For example, there are now classes in auto repair specif i- cally intended for women. As a result, women are sometimes seen working on a car. As women increase their mechanical skill, they, too, are being afforded the opportunity to exercise more control over their own lives, giving them new power over the obstacles of the contemporary world. Thus presuming the continued growth of new feminism, women may not relish re- linquishing this aspect of their newly acquired independence. A decrease in independence and self-reliance also has an eco- nomically tangible side--the increased cost of automobile upkeep for persons who have in the past performed some of their own auto repairs. 239 PAGENO="0443" 437 For persons unable to afford the cost of repair work, this would probably be seen as a discriminatory feature of hydrogen car ownership. Many automobile onwers show an increasingly resistive attitude towards automobile mechanics while the increased complexity of automo- biles has made it increasingly difficult for the individual to know if he has been treated honestly. The founding of an agency in California to handle consumer complaints against automobile mechanics and the sub- sequent large number of complaints received is an indicator of this dis- trust. This attitude is likely to persist and would increase the impor- tance of reduced self-reliance. An especially important practical consideration will be the decreased ability of owners of hydrogen-fueled cars to handle emergency mechanical breakdown situations especially those involving the fuel sys- tem. This may be a major consideration for individuals who live or travel in rural or remote undeveloped areas. 4. Derived from a Reduction in Air Pollution The reduction in air pollution derived from the use of hydro- gen automobiles is a source of potential major positive impact on health and aesthetics. As air quality has declined, the relationship between air pollution and respiratory ailments has become widely recognized.30 The benefits of reduced air pollution from hydrogen cars would affect the populace differentially, of course, but those who live or work in large urban areas, where pollution is at its worst, would benefit most. In particular, the poor, the aged, and those in ill health, who are often unable to escape the urban environment, would derive the most health benefits from reduced air pollution. The relationship between air pollution and aesthetic values has also gained recognition, especially in relation to the deterioration 240 PAGENO="0444" 438 of objects (including works of art), reductions in visibility, and the presence of noxious odors. As with health benefits, society as a whole would be affected by increased quality of the environment, but the pri- mary benefactors would be those individuals living in communities that suffer from extreme air pollution. In addition some psychological bene- fits might be derived solely from the knowledge that a step is being taken to improve the environment. 5. Derived from Independence from Foreign Energy Sources Having experienced the energy crisis in the winter of 1973- 1974, Americans now realize more clearly that fossil fuel resources are limited and that, as a nation, we depend on other countries to supply our increasing demands for liquid fuel. The use of hydrogen fuel de- rived from nonfossil sources could have major impacts on the sense of security of both the individual and the nation as a whole. Although use of hydrogen as fuel could not quickly reach major proportions, the sense of uneasiness about dependence on other nations for fuel is likely to still be present when the hydrogen era might begin. Judging from overheard conversations and news reporting, Americans now suffer feelings of anxiety concerning their individual freedom due to the recent energy crisis' and the potential for more frequent and larger crises. Many of the deeply held values in our society--geographic mobility, personal freedom, recreation, tourism, prestige, material status, and privacy--are derived in part from pri- vate ownership and operation of the automobile. Should the availability of automotive fuel decrease drastically or its price become very high, considerable changes in individual life-styles would follow. These threats are likely to persist and to become even stronger in the era when hydrogen cars might begin to be deployed. The availability of 241 PAGENO="0445" 439 hydrogen as a fuel might enhance feelings of individual freedom by les- sening the threat of fuel shortages. Knowledge that as a nation we were not dependent on other nations for such a basic necessity as fuel might add to a strong na- tional feeling. This is not necessarily beneficial, however, for it could prove detrimental to international relations. It is now recog- nized that interdependence of nations helps to keep communications open between them. If nations were to become totally independent with re- spect to such a basic need as energy, and this reduced the need for communication and conciliation, then the possibility of misunderstanding and conflict might increase. In a world of many nations, with conflict- ing philosophies, interdependence may be an important ingredient in maintaining peace. 6. Impacts of Hydrogen Filling Stations Hydrogen filling stations will probably be larger than their gasoline counterparts29 because there would be requirements for extra facilities to capture and reliquify vaporized liquid hydrogen or, per- haps, to store and rejuvenate metal hydride beds. Simply to supply an equivalent amount of energy, a liquid hydrogen station would have to store about three times as many gallons of liquid hydrogen as it would gasoline and would also require proportionally more deliveries. Alter- natively, if the hydrogen were liquif led on-site, sizable liquefaction facilities would be required. Moreover, for safety, a larger peripheral buffer of vacant land would probably be required than for a gasoline station--unless the present standards2g* for hydrogen handling are re- laxed (an unlikely prospect). *For example, a 19,000 gallon liquid hydrogen storage tank must be at least 25 feet from the nearest roadway and 75 feet from the nearest building 29 242 PAGENO="0446" 440 The mere size of a hydrogen filling station might become a source of land use conflict. Besides the larger size of a hydrogen filling station stemming from the physical properties of hydrogen, early in the transition period away from gasoline-powered cars hydrogen f ill- ing stations would probably be few in number (to ensure operating econ- omies) and probably have a larger capacity than they would in a steady- state, all-hydrogen automotive system. These filling stations would have several impacts on citizens residing or working in the neighborhoods where the stations were located. First, an abnormally large number of cars would be required to converge on the few hydrogen filling stations and this would tend to increase traffic congestion and noise in the vicinity. Additionally, the con- vergence of traffic would probably induce changes in neighborhood makeup as merchants would probably preferentially seek locations nearby because of the commercial attractiveness of such a strategic point. A direct impact resulting from the density and placement of hydrogen filling stations, particularly during transition, would be the decreased freedom of mobility of persons operating hydrogen cars. Ini- tially, hydrogen filling stations could not be available in all areas, especially in low density rural areas. Consequently, the initial hydro- gen car owners may be only those who also have access to a conventional gasoline-fueled automobile. Thus, ownership of a hydrogen automobile may initially be limited to families able to afford more than one auto- mobile, with the hydrogen-powered vehicle being largely confined to local use. Although a hydrogen filling station may prove safer than a gasoline filling station, there would be increased exposure to hazards from the increased number of hydrogen delivery vehicles on the road. This would increase the probability of accidents involving delivery 243 PAGENO="0447" 441 vehicles. Even though the magnitude of this impact is not very high, there are enough accidents today involving gasoline delivery trucks to warrant attention to the potential hazard. C. Economic Impacts There were about 101 million automobiles in operation in 1973 in the United States.7 Of these, about 100 million were operated privately as personal vehicles.7 About 9.6 million new cars were sold in 1973 and the replacement rate generally runs about 10 percent per year.7 These vehicles represent an initial value investment of about $250 billion and have a present value of about $85 billion. Although new automobile prices have increased rapidly in the last several years,* automotive maintenance and ownership contributed about $103 billion in 1973, or 13 percent, to total personal consumption expenditures.13 Although it is difficult to estimate the total cost of a hydrogen- fueled automobile in the distant future, the cost of automotive hydrogen fuel storage systems can be estimated. For example, it has been esti- mated that in mass production the cost of liquid H2 containers holding 2 million Btu (the energy equivalent of 16 gallons of gasoline) could be lowered to approximately $1200 to $1800 each (compared with $2000 each in 1972) .~ Other manufacturers, such as Minnesota Valley Engi- neering Company, estimate that dewars might cost $300 to $400 when mass produced.33 Since the technology and manufacturing of small cryogenic dewars is well established, further cost reductions are unlikely without new materials or new concepts. The safety requirements of vehicle sto- rage systems are likely to have a significant impact on dewar costs. *Largely because of new air quality, safety, and crash worthiness regulations. 244 PAGENO="0448" 442 Current containers for liquid hydrogen are built for stationary appli- cations, but the need to be able to withstand high-speed impacts from any direction is almost certain to increase cost estimates. Costs of storage in the form of a metal hydride would depend on the metals employed. The Futures Group estimated that a magnesium hydride system for automobiles would cost about $47O,~~ but today there is no large volume production of metal hydrides on which to base estimates. In recent years, magnesium has fluctuated around $0.38/lb35*; assuming 500 lbs of magnesium were used per car,12 the cost of the magnesium alone would be approximately $190. Fabrication costs could easily double the cost. A magnesium-nickel hydride (Mg2NiH2) capable of holding 37 ft3 (2 x 106 Btu) of hydrogen would weigh about 1000 lbs. With magnesium at $0.38 per lb and nickel at $1.50 per lb,36 the material costs alone would be about $1000. By comparison, an average gasoline tank weighs about 25 lbs and can be manufactured for about $30.32 The availability of metals for hydrides will depend on a gradual buildup of consumption. The worldwide resources of magnesium are vast *because magnesium salts are abundant in seawater. In the United States, large-scale production of magnesium is concentrated in Utah and Texas. In 1973, the U.S. primary and secondary production of metal was 140,000 short tons, but under wartime conditions, magnesium output was increased from 5,570 tons in 1940 to 155,000 tons in 1943--a level only now being regained.~7 At a use rate of approximately 500 lbs of magnesium per car, 250,000 tons would be needed for every one million new cars--or roughly 70 percent more than current domestic magnesium production. Although *Since magnesium production is energy intensive, these costs can be ex- pected to rise (in constant dollars) to reflect the rising cost of energy. 245 PAGENO="0449" 443 about 10 million cars are normally produced each year, judging from wartime experience, the implied additional production capability could apparently be brought on line. Magnesium-nickel hydrides could not be introduced as easily. Roughly 530 lbs of nickel would be required per car. This means that 265,000 tons of nickel would be required for every one million cars produced. Consumption of nickel in the United States in 1973 was about 195,000 tons, with nearly all of its (180,000 tons) imported. Canada is currently the main source of U.S. nickel imports, but the future availability of nickel at current prices is doubtful in light of recent Canadian actions to preserve their resources (oil and gas) for their own use. The very high cost and weight (with an implied vehicle fuel effici- ency penalty) of magnesium-nickel hydride virtually rules out its use in automobiles. Even the high cost of magnesium hydride would lead to some important socioeconomic impacts. First, during a transition when gasoline cars were still available in competition, the implied increased cost of this type of a hydrogen-fueled automobile could discourage buyers from making a purchase. This would particularly affect persons margi- nally able to afford new cars. Second, the cost of the hydride would carry over to the resale value of the car because the magnesium hydride would retain value as scrap. As a result, prices of used hydrogen cars would also be higher than their gasoline counterparts and this would have a negative impact on those individuals who can only afford low cost used cars. A positive effect of the high scrap value of a hydride bed (or a stainless steel liquid hydrogen dewar) would be the increased incentive for vehicle recycling because of the improved economic return to auto dismantlers (normally very marginal businesses). This same residual 246 62-332 0 - 76 - 29 PAGENO="0450" 444 attractiveness, however, would tend to spread the threat of theft to old cars, which are essentially immune to theft today because of their small residual value. The investment in the present automobile fuel system may be esti- mated from the assets of the U.S. petroleum industry by separating the natural gas and chemical production assets of the large integrated com- panies. Since roughly 50 percent of refinery output is gasoline, it can be assumed that 50 percent of the value of refineries and supporting facilities can be assigned to the gasoline distribution system. The net value of production, refining, and distribution assets of the petroleum industry was $50 billion in December l973;38 this is roughly half the original or gross investment value of $102 billion.38 The major compo- nents of this investment assigned to the gasoline distribution system are shown in Table 14-3. Table 14-3 ESTIMATED INVESThENT IN U.S. GASOLINE DISTRIBUTION SYSTEM--DECEMBER 1973 Production assets $14.4 billion Transportation and distribution 22.3 Refineries 3.6 Marketing and administrative 7.5 $27.8 billion Source: Reference 38. 247 PAGENO="0451" 445 To change the present automotive fuel system from gasoline to hydrogen would require complete replacement of all present facilities, Hydrogen fuel stations would probably number far less than the 218,000 gasoline stations in the United States in January l973.~~ Electrical generating capacity and electrolytic hydrogen production sufficient for 100 million cars would require deployment of about 540 l-GW nuclear power plants (for example), and, although there is debate about the future cost of nuclear electric plants, at $560 per kW (1973 dollars)* the total electric plant investment would be about $300 bil- lion (1973 dollars). The electrolysis facilities could cost about $18 billion (1973 dollars) and liquefaction facilities could cost about $20 billion (1973 dollars).t Thus the total investment would be about $340 billion (1973 dollars). Because there will be many competing uses for investment funds of this magnitude, such investment would have to be spread over a long period of time. The investment needed for hydrogen distribution and marketing f a- cilities would be in addition to the $340 billion already discussed. The future cost of a hydrogen fuel station will obviously depend on the nature of the facility; if it is analogous to today's service station, then it will provide repair and maintenance services as well as fuel. It will quite likely be larger and more costly than present gasoline stations because of more costly storage and transfer facilities. Cur- rently, the average cost for new gasoline stations is about $250,000 for land and buildings;4° at this rate, a low estimate for 100,000 new hydro- gen filling stations would require $25 billion. *See Chapter 16 for a discussion of nuclear power plant investment costs. f See Chapter 11 for a discussion of these investment costs. 248 PAGENO="0452" Liquid Hydrogen Car 1,2 ___________ (59%) (77%)3 (90%) (99°/a) (29%) ___________________ Penalty Factor Engine H [12] Coal ~ Liquefaction j......._~ Storage, Distribution, ,,,,,,,,j Relative Weight, ~ Use in and Transfer (33%) (8OE%) (77%)3 (90%) (99%) (29%) Use in Relative Weight, Nuclear ,,_,,JEiectrolytic 1 Li~uefac~~j___._a[ Storage, Distribu~~ ]1 Penalty Factor j[ ginej"" 5] Electricity Hydrogen `""~________________ and Transfer __________________ ___________ Electric Car (83 ~ _____________ (38%) (90%) (9O%l~ (8o%)~ ~ Relative ~ (8O%)~ Transmission ,~ Battery ,,,,~[ Battery Weight Us. In L Coal ~HI Electricity Hand_Distribution Charge Discharge Penalty Vehicle_H [16] Factor (83 0/s) 6 (33 %) (90%) (9O%)~ (8O%)~ j_,,,~ Relative ~ (8O%)~ and Distribution Charge Discharge Penalty Veh~j~ [14] ______________________ Transmission Battery ~ Battery Weight Use in Factor %,) INDIVIDUAL PROCESS EFFICIENCIES [ 0/] NET SYSTEM EFFICIENCIES FIGURE 14-3. ENERGY RESO~JRCE UTILIZATION OF HYDROGEN FUELED AND ELECTRIC CARS NOTES: I. INCLUDES ENERGY UTILIZATION FOR COAL TO PRODUCT, COAL FOR PROCESS HEAT, AND COAL FOR STEAM AND ELECTRICITY 2. SRI INTERNAL DATA 3. REFERENCE 30 4. REFERENCE 41 5. ASSUMES A BATTERY AND ANCILLARY EQUIPMENT AEIGRT OF ABOUT 1500 Ib~. PAGENO="0453" 447 The total investment in electrical generating plants and electrol- ysis and liquefaction plants could easily exceed $250 billion for 100 million vehicles. This compares to a total investment of about $113 billion for the entire U.S. petroleum industry (including natural gas and petrochemical facilities) in 1973.38 The gasoline fuel distribution system employed about one million persons in l973.~ Although it is very difficult at this time to esti- mate the employment needs of individual components of a potential liquid hydrogen (for example) automotive fuel system, it is reasonable to expect that it would employ about the same number of people. In 1973 consumers paid $4.7 billion (net of premiums less claims paid) to the automobile insurance industry.7 This industry would surely become involved in the question of the relative safety of hydrogen vehicles. The recent trend, illustrated by the public issues of crash- worthy bumpers, air bags, and no-fault insurance, is for automobile insurance companies to try to influence both public and congressional attitudes through advertising and lobbying. As discussed in Chapter 8 the issue of hydrogen safety is too complex to decide now whether a hydrogen car would warrant the opposition or support of the insurance industry in advance of actual large-scale experience. D. Resource Utilization Transition to a hydrogen-fueled automotive system would not be the most efficient use of the U.S. energy resources. As Figure 7-7 showed, the net cascaded system efficiency of hydrogen automotive systems is inferior to other synthetic fuel alternatives based on the same re- sources--even allowing for the claimed superior efficiency of hydrogen combustion in engines. Figure 14-3 extends the comparison further by comparing the coal and nuclear based hydrogen systems shown in Figure 7-7 250 PAGENO="0454" 448 with coal and nuclear based electric car systems employing the still speculative technology of lithium sulfur batteries.41 Figure 14-3 demonstrates that a transition to a hydrogen-fueled automotive system is less compatible with a future in which stringent energy conservation would place a premium on optimum use of basic energy resources than a transition to advanced electric cars. Because the electric car would probably be even more beneficial for urban air quality than the hydrogen car (no nitrogen oxides but a small amount of ozone), considerable public debate over the relative merits of these options must be expected before either one is chosen.* Unless, however, advanced lithium sulfur (or the equivalent) high energy and high power density batteries become practical, the future of the elec- tric car is not bright. Just as considerable discussion over the safety aspects of hydrogen automobiles is to be expected, so there would be debate about any battery involving moltent alkali metals (such as lithium or sodium) because alkali metals are very dangerous substances when they contact moisture or water and nearly all metals are dangerously hot when molten. E. Fleet Vehicles 1. Decisions to Deploy Because fleet vehicles require so much less in the way of a fuel distribution network, they can be more readily deployed and sup- ported. Accordingly, the implementation scenarios of Chapter 13 show *Ozone is a powerful oxidizing agent and is a key oxidant product of photochemical smog--reaction products of unburned hydrocarbons, nitro- gen oxides, and sunlight.30 f The lithium sulfur battery has an operating temperature of about 400°C (750°F) *30 251 PAGENO="0455" 449 hydrogen-fueled fleet vehicles coming into use sooner than their pri- vate automobile counterparts. It is extremely significant that fleet operators normally provide the fuel for their own vehicles by means of `fleet accounts" with oil companies,3 thereby eliminating the need for a series of public filling stations. The prospect and possible guaran- tee of a bulk sale to a fleet operator would be more attractive to sup- pliers than sales on the open market to many individual owners.3 Con- sequently, the three-way dilemma mentioned earlier for private auto- mobiles is easier to surmount and more readily resolvable in the fleet vehicle context because the decision of a single fleet owner can affect the sale of a large number of vehicles and their fuel. Moreover, fleet operators are mainly interested in the economics of purchase, mainte- nance, and operation rather than in the less tangible psychological aspects of car ownership. Thus, when a convincing case in favor of hydrogen-fueled cars or vans can be made on these grounds, even a few favorable fleet operator decisions could create a market large enough to initiate commercialization. For example, a few decision-makers in the New York City or Washington, D.C., taxi business could lead to com- plete use of hydrogen-fueled taxis in those cities, and this would encompass hundreds of cars and commercially significant amounts of fuel. It is also very important that some of the most significant fleet operators are the federal, county, and municipal governments that have a wider range of concerns and objectives than either individual car owners or commercial fleet operators. Governments could decide to implement hydrogen as a fuel for their fleet vehicles (even at higher cost) solely on the basis of providing a "good example" for the improve- ment of air quality. Today such municipal decisions are, in fact, being made for propane-powered cars and small buses. Some electric vehicle makers are seeking to establish a beachhead by recourse to such decision- making. The most notable example is the trial of a small fleet of 252 PAGENO="0456" 450 electric powered postal delivery vans by the Post Office.42 If success- ful, the 240,000 light-duty postal vehicles would present a substantial initial market. 2. Impacts By far, the single most important impact stemming from experi- ence with hydrogen-powered fleet vehicles would be the psychological and educational conditioning effect on the public and the establishment of a rudimentary hydrogen fuel distribution network that could be expanded into a more general system for general automotive use. Successful dem- onstration of safe, economical, and reliable operation of hydrogen- powered urban buses would probably yield the most conditioning of the general public--either for or against hydrogen. However, because buses are commonplace, readily identified, and are entrusted with the simul- taneous safety of many people, the question of hydrogen's actual (or perceived) safety will be particularly salient. It is likely, however, that public reticence about hydrogen- powered buses will be pronounced, and their introduction may require prior successful experience in privately owned fleet vehicles. Munici- pal governments, labor unions (especially for drivers), the riding pub- lic, and the general public (each of whom might be involuntarily exposed as a bystander) must all be convinced that a hydrogen-powered bus is safe enough to warrant a try. Municipal officials, with ultimate re- sponsibility to the public through elections, can be expected to be cautious in embracing a new technology if a significant number of con- stituents express concerns over safety. Labor unions, because of their ability to articulate the collective concerns of their members, would 253 PAGENO="0457" 451 also play a significant role in decisions to deploy hydrogen-powered buses . * Many of the impacts to be expected for use of hydrogen in private vehicles would be unimportant for fleet vehicles or lesser in magnitude. In particular: * Decreased personal ability to repair the fuel system is basically irrelevant because the fleet owner rather than the driver normally provides the repair service. * Safety education would be facilitated by incorporation into existing operator training programs. * Air quality improvement potential would be less because fleet vehicles account for about 30 percent of all mileage in the automotive sector. * The effect of increased initial cost would be less because fleet owners use business accounting methods that allow capital recovery through depreciation. * Fleet-owned filling stations are privately and exclusively operated, so merchants would not be attracted to the vicin- ity, thereby lessening the secondary land-use impact of filling stations. F. Summary In general, use of hydrogen in fleet vehicles can be expected to precede use in private vehicles and to establish the general attitude of the public towards hydrogen-powered automotive vehicles. Table 14-4 summarizes the impacts that would be expected from automotive use of hydrogen. *Labor unions could be expected to have a voice in nearly every use of hydrogen in fleet vehicles. 254 PAGENO="0458" Table 14-4 SOCIETAL IMPACTS OF A TRANSITION TO HYDROGEN-FUELED PRIVATE AUTOMOBILES AND FLEET VEHICLES Magnitude of Impact Impact Class Stakeholders Nature of Effect (units) PRIVATE AUTOMOBILES Economic * Investment required for * Oil companies * Large demand for capital to * Major ($) production and (listribu- * Utilities supplant present system tion of hydrogen fuel * Capital market * Investment required to * Auto manufacturers * Large demand for capital to * Major ($) produce new class of * Component manu.fac- supplant present system vehicles turers * Development of new markets * Cryogenic industry * Cost of vehicles, fuel, * Consumers * Access to vehicles may be * Major ($, people) maintenance, and repair restricted by higher costs Institutional * Insurance * Insurance companies * Effect of safety experience * Moderate ($, people) * Consumers on insurability * Ownership of fuel * Public energy * Competition for control of * Major (power) distribution system utilities hydrogen fuel markets * Oil companies * Pipeline companies * Gas producers PAGENO="0459" Table 14-4 (continued) Magnitude of Impact Nature of Effect (units) * Expanded regulatory authority * Major (power) over synthetic gas and sub- sequent uses of hydrogen * Safety and performance criteria 01 C) * Fuel distribution * Vehicle maintenance and repair * Dealer and employees * Unions * Customer * Mechanics * Unions * Specialized training to handle more exotic fuel and materials * Specialized training to deal with more sophisticated systems * Moderate (people, $) * Moderate (people) * Industrial shifts * Factory workers * Threat to employment as industry changes * Minor (people, $) Individual Values * Personal safety * Vehicle passengers * Service personnel * Emergency crews * Bystanders * Real or perceived threat to personal safety by exposure to hydrogen * Major (people) Impact Class Stakeholders * Regulatory Labor Force * Hydrogen fuel distributors * Government regulatory bodies * Hardware producers PAGENO="0460" Table 14-4 (continued) Magnitude of Impact Impact Class Stakeholders Nature of Effect (units) * Independence/Self- * Vehicle owners * Increased reliance on * Moderate (people) reliance specialized station attendants, mechanics * Vehicle users * Altered freedom of mobility * Health * Urban residents * Improved air quality * Minor to major as * Governments affecting health transition proceeds (people, $) * Aesthetics * Urban residents * Decreased deterioration of * Minor to major as objects by air pollution transition proceeds O~ * Increased visibility (people, $) * Decreased noxious odors * Sense of personal * Individuals * Lessened fear of interrup- * Minor (people) freedom tion of life-style caused by actions of foreign gov- ernments regarding energy supplies National Security * U.S. citizens * Independence from foreign * Major (people) control of fossil fuel resources Resource Utilization * Society * Suboptimum use of basic S Very major ($) energy resource compared to alternatives PAGENO="0461" Table 14-4 (concluded) Magnitude of Impact Impact Class Stakeholders Nature of Effect (units) Land Use * Nearby residents * Increased size of filling * Minor (people) stations and traffic density, changing land use in vicinity FLEET VEHICLES Safety * Labor unions * Perceived or actual hazards * Moderate (people, $, 4~ associated with use of power) hydrogen PAGENO="0462" 456 REFERENCES 1. "History and Future of Spark Ignition Engines," a report prepared by the Environmental Policy Division of the Congressional Research Service, Library of Congress, for the Committee on Public Works, United States Senate, at the request of Senator Edmund S. Muskie, 93rd Congress, 1st Session (September 1973). 2. "Gasoline: EPA Issues Rules, Proposal on Availability of Unleaded Gasoline," Energy Users Report (9 May 1974), pp. C-2 and C-3. 3. F. H. Kant et al., "Feasibility Study of Alternative Fuels for Automotive Transportation," Vol. I: Executive Summary; Vol. II: Technical Section; Vol. III: Appendices, a report by Exxon Re- search and Engineering Company, Linden, New Jersey, for the U.S. Environmental Protection Agency (June 1974). 4. J. Pangborn and J. Gillis, "Alternative Fuels for Automotive Trans- portation--A Feasibility Study," Vol. I: Executive Summary; Vol. II: Technical Section; Vol. III: Appendices, by the Institute of Gas Technology, Chicago, Illinois, for the U.S. Environmental Protection Agency (June 1974). 5. E. Dickson et al. "Impacts of Synthetic Liquid Fuel Development for the Automotive Market," by Stanford Research Institute, Menlo Park, California, for the Energy Research and Development Adminis- tration, Washington, D.C. (report in preparation). 6. J. E. Johnson, "An Economic Perspective on Hydrogen Fuel," in Hydrogen Energy, T. N. Veziroglu, ed. (Plenum Press, New York, 1975), pp. 299-308. 7. Statistical Abstract of the United States, 1974 (Bureau of the Census U.S. Department of Commerce, July 1974). 8. R. E. Billings and F. E. Lynch, "Performance and Nitric Oxide Con- trol Parameters of the Hydrogen Engine," report No. 73002, Billings Energy Research Corporation, Provo, Utah (April 1973). 259 PAGENO="0463" 457 9. J. G. Finegold et al., "The UCLA Hydrogen Car: Design, Construction and Performance," paper No. 730507, presented at the Society of Automotive Engineers, Automobile Engineering Meeting, Detroit, Michigan, 14-18 May 1973. 10. J. G. Finegold and W. D. Van Vorst, "Engine Performance with Gaso- line and Hydrogen: A Comparative Study," in Hydrogen Energy, T. N. Veziroglu, ed. (Plenum Press, New York, 1975), pp. 685-696. 11. R. R. Adt et al., "The Hydrogen-Air Fueled Automobile Engine," 8th Intersociety Energy Conversion Engineering Conference, 1973, pp. 194-197. 12. A. L. Austin, "A Survey of Hydrogen's Potential As a Vehicular Fuel," UCRL-5l228, University of California Radiation Laboratory, Livermore, California. 13. R. J. Schoeppel, "Design Criteria for Hydrogen Burning Engines," final report, EPA Contract EHS-70-l03 (October 1971). 14. P. B. Dieges et al., "An Answer to the Automotive Air Pollution Problem," First Annual Report, Perris Smogless Automobile Associ- ation, Perris, California (undated). 15. P. Underwood and P. B. Dieges, "Hydrogen and Oxygen Combustion for Pollution Free Operation of Existing Standard Automotive Engines," 6th Intersociety Energy Conversion Engineering Conference, 1971, pp. 317-322. 16. "Fuel of the Future," Time (11 September 1972), p. 46. 17. L. Lessing, "The Coming Hydrogen Economy," Fortune (November 1972), pp. 138-146. 18. "When Hydrogen Becomes the World's Chief Fuel," Business Week (23 September 1972), pp. 98-102. 19. W. Clark, "Hydrogen May Emerge as the Master Fuel to Power a Clean Air Future," Smithsonian (August 1972), pp. 13-18. 20. P. Gwynne, "The Hydrogen Car," New Scientist (18 October 1973), pp. 202-203. 260 PAGENO="0464" 458 21. R. Breshears, H. Cotrill and J. Rupe, "Partial Hydrogen Injection into Internal Combustion Engines, Effect on Emissions and Fuel Economy," presented at the Environmental Protection Agency, The First Symposium on Low Pollution Power System Development, Ann Arbor, Michigan, 14-19 October 1973. 22. W.J.D. Escher, "Survey and Assessment of Contemporary U.S. Hydrogen- Fueled Internal Combustion Engine Projects," 10th Intersociety Energy Conversion Engineering Conference, Newark, Delaware, 18-22 August 1975. 23. A. Hammond, "Fission: The Pro's and Con's of Nuclear Power," Science (13 October 1972), pp. 147-149. 24. M. Willrich and T. B. Taylor, Nuclear Theft: Risks and Safeguards (Ballinger Publishing Company, Cambridge, Massachusetts, 1974). 25. "Compilation of Air Pollutant Emissions Factors," U.S. Environmental Protection Agency (1973). 26. "[President] Ford Asks 5-Year Freeze on Auto Emissions Curbs," New York Times (28 June 1975), p. 42M. 27. "Environmental Considerations in Future Energy Growth," Vol. I, by Battelle Memorial Research Institute for the Office of Research and Development, Environmental Protection Agency, Contract #68-01- 0470 (April 1973). 28. "Draft Environmental Statement for the El Paso Gasification Project, San Juan County, New Mexico," prepared by the Upper Colorado Region, Bureau of Reclamation, U.S. Department of the Interior (16 July 1974). 29. W. E. Stewart and F. J. Edeskuty, "Logistics, Economics, and Safety of a Liquid Hydrogen System for Automotive Transportation, presented at the Intersociety Conference on Transportation, Denver, Colorado, 23-27 September 1973. American Society of Mechanical Engineers Publication 73-ICT-78. 30. 5. J. Williamson, Fundamentals of Air Pollution (Addison-Wesley Publishing Company, Reading, Massachusetts, 1973). 31. Survey of Current Business, Bureau of Economic Analysis, Social and Economic Statistics Administration, U.S. Department of Commerce (July 1974), p. 24. 261 PAGENO="0465" 459 32. J. E. Johnson, "The Storage and Transportation of Synthetic Fuels," a report to the Synthetic Fuels Panel working on the Federal Coun- cil on Science and Technology R&D Goals Study (September 1972). 33. Mr. William J. D. Escher, Escher Technology Associates, St. John's Michigan (personal communication). 34. E. Fein, "A Hydrogen Based Energy Economy," The Futures Group, Glastonbury, Connecticut (October 1972). 35. "Commodity Data Summaries, 1974, Appendix I to Mining and Minerals Policy," Bureau of Mines, U.S. Department of the Interior. 36. "Commodity Data Summaries, 1974, Appendix I to Mining and Minerals Policy," Bureau of Mines, U.S. Department of the Interior. 37. J. Paone, "Magnesium" in Mineral Facts and Problems, Bureau of Mines Bulletin 650 (1970). 38. "Capital Investment of the World Petroleum Industry, 1973," Chase Manhattan Bank, New York, New York (December 1974). 39. "The Vacancies on Gasoline Alley,' Business Week (15 December 1973), pp. 20-21. 40. National Petroleum News, Factbook Issue, 1974 (March 1974), p. 58. 41. P. A. Nelson et al., "The Need for Development of High Energy Batteries for Electric Automobiles," Argonne National Laboratory Report ANL 8075 (November 1974). 42. "When Electric Trucks Deliver the Mail," Business Week (Industrial Edition) (9 March 1974), pp. 78C-78F. 43. W. R. Parrish and R. 0. Voth, "Cost and Availability of Hydrogen," in "Selected Topics on Hydrogen Fuel," J. Hord, ed., Report NBS IR 75-803, Cryogenics Division, National Bureau of Standards, Boulder, Colorado (January 1975). 262 62-332 0 - 76 - 30 PAGENO="0466" 460 CHAPTER 15--COMMERCIAL AVIATION A. The System and the Stakeholders Commercial aviation is a complex, capital and energy intensive system. Since World War II, the United States has been the leader in aviation technology, the production of aircraft, and commonplace air travel.* The chief stakeholders in the U.S. commercial aviation sector are the * Airlines * Aircraft manufacturers - Airframe - Engines * Airport operators * Fuel producers and distributors * Government regulatory agencies - Markets and fares (Civil Aeronautics Board[CAB] - Safety, air traffic control, and navigation (Federal Aviation Agency[FAA] - Noise (EPA and FAA) - Fuel use (Federal Energy Administration [FEA] * Consumers Transition to a hydrogen-fueled aviation system in the United States would affect all these stakeholders as well as their counterparts in *In the noncommunist portion of the world, about 83 percent of the com- mercial jet aviation is U.S.-built, and 43 percent is U.S.-operated. 263 PAGENO="0467" 461 foreign nations--especially since the United States has been the domi- nant supplier of commercial aircraft. As discussed elsewhere in this report, the fuel distribution net- work is a key element in any transportation system. Clearly, a hydrogen- fueled airplane cannot operate without assured distribution of fuel. In strong contrast, however, to the automotive sector where the final link in the fuel distribution network is manifested by small, nearly ubiqui- tous filling stations,* just a few airports account for most of the fuel dispensed in commercial aviation. The top 10 aviation hubst accounted for 70 percent of all the domestic plus international enplanements in 1968.1 To illustrate, Figure 15-1 shows the top 23 air traffic hubs in the contiguous United States.2 Thus, if hydrogen-fueled commercial air- craft were deployed, a very large portion of the commercial air trans- portation system could be fueled from only a few major airports. More- over, the low number of major air traffic hubs is a parallel *to the favorable situation found in fleet automotive application where rela- tively few decision-makers control the outcome. 1. The Airlines As potential operators of hydrogen-fueled aircraft, the domes- tic U.S. trunk airlines have an especially important stake. As shown *In 1974 there were about 215,000 gasoline filling stations in the United States. tA "hub" may consist of several airports such as Kennedy, LaGuardia, and Newark in the New York hub. The ten hubs with the most enplanements in 1968 were (in descending order): New York, Los Angeles, Chicago, San Francisco, Atlanta, Miami, Washington, Boston, Dallas, Honolulu. 264 PAGENO="0468" 462 in Figure 15-2, new generations of airplanes have been introduced at 10- to 12-year intervals.3 Each succeeding generation offered important advances in speed, capacity, and passenger comfort and adoption of each was essential to enable individual airlines to attract and hold passen- gers because competition had become increasingly a matter of service and cost reduction rather than ticket price differentials. Indeed, ticket prices have been regulated by the government to such an extent that ex- cept for special restricted fares* the basic rates have been identical. Service differential aspects of competition have been manifested in *With stipulations on length of stay, age of the traveler, familial re- lationship of passengers, etc. FIGURE 15-I. MAJOR AIR TRAFFIC HUBS (1973) 265 PAGENO="0469" U) Lii -J Lii z Lii U) U) Lii z Lii > Lii -J 4 z z 4 SOURCE: Reference 3 463 FIGURE 5-2. U.S. DOMESTIC TRUNKS-SCHEDULED SERVICE, 48-STATE BASIS (The 10- to 12-year cycle of new aircraft introductions is clearly shown.) * Passenger amenities (meals, seat and legroom, alcoholic drinks, inf light movies, etc.) * Solicitous service * Schedule frequency * Low load factors.* But even these distinctions have tended to even out because within a few years after the introduction of new aircraft, airlines not only fly basi- cally the same equipment (with only minor variations in interior appoint- ments) but they also closely emulate each other in service. *The fraction of available seats occupied by passengers on any given flight. FORD TRI-MOTOR DC-3 DC-6 NARROW-BODY WIDE-BCDY * PLOTTED ON A 50 STATE BASIS JETS JETS* YEAR END 266 PAGENO="0470" 464 The newest generation of commercial aircraft--the "wide-body jets--appear to be nearing the feasible limits of passenger comfort amenities. Meanwhile, airlines are becoming increasingly pressed for funds for capital investment and in operating costs--especially for fuel. As a result, it is widely assumed in the industry that the next genera- tion of aircraft will have to offer airlines significant operational savings to gain acceptance.48 Airlines will be especially interested in the following factors for future aircraft: * Initial cost * Energy utilization * Availability of specified fuel * Cost of specified fuel * Maintenance and other operating costs * Efficiency of aircraft turnaround on the ground * Labor utilization * Environmental acceptability In addition, increasingly stringent noise abatement regulations are adding to the financial concern of airlines5 because of the high cost of retrofiting engines to make them quieter and the effect of airport curfews on scheduling. Thus, under the pressure of governmental noise regulations, airlines will also be seeking much improved noise perform- ance in new aircraft. 2. Aircraft Manufacturers The makers of finished airplanes and engines normally work closely with the airlines during the design of new aircraft. Through this interaction, new designs for airplanes generally reflect advances in technology and the airlines' desires.9 Not all airlines have an equal voice, however, in any given design. Those operating the largest 267 PAGENO="0471" 465 or traditionally the most modern fleets are naturally the most courted potential buyers. Thus, the basic aircraft finally offered for sale may especially reflect the needs of one or just a few airlines.* The development of new aircraft entails substantial economic risks. Because of the enormous development costs of present-day air- craft, the cost per airplane is sensitive to the (small) number produced and sold. Development costs have exceeded $1 billion for each of the most recent generation of wide-body airplanes.' At a sales price of $25 million, 400 aircraft sales are needed to bring the average devel- opment costs down to 10 percent of the sales price (i.e.,$2.5 million) a reasonable goal. To show a profit on a new airplane, an airframe manufacturer must assess the size of the market accurately and spread development costs appropriately. If a sales goal of 400 planes is missed by 100 planes, then the company must absorb 25 percent of the development costs. It is common knowledge1° that it will be many years before the wide-body jets reach the sales goals of their makers.t Besides the risks involved in estimating the size of the mar- ket, manufacturers have a major problem of cash flow associated with the long lead times, large development costs, and large expenditures to get into production. When ten years elapse between the design go-ahead and the date of first delivery, even when followed by reasonable *For example, the Lockheed Electra design largely reflected the needs of Eastern Airlines for making landings at the relatively difficult La- Guardia Airport in New York and (for the era) carried more sophisticated electronic gear than many other airlines really desired. The design of the Boeing 747 was slanted towards Pan American's anticipated needs on long-range, transocean routes, and as a result has proved less satis- factory on the shorter domestic routes of other airlines.9 fLockheed reportedly is charging R&D costs of the L-lOll against minimum sales of 300 airplanes. In mid-1975, 143 more sales are needed to meet that goal.'° 268 PAGENO="0472" 466 production rates, cumulative cash flow can be negative for 15 years. At the end of 1972 the net worth of each of the three major air trans- port manufacturers was under $1 billion, as shown in Table 15-1. Thus, the commitment to develop a new generation of planes involves a decision to risk the entire stockholder equity, a process that has been termed "betting the company." Table 15-1 NET WORTH OF AIRFRAME MANUFACTURERS (1972) Net Worth Company (millions of dollars) Boeing $865 McDonnell Douglas 834 Lockheed 266 An important factor affecting manufacturers' decisions to embark on development of hydrogen-fueled aircraft is the futifre policy of the Department of Defense (DoD). Historically, technological advance in the aviation industry has been spawned by DoD needs for ever more sophisticated air weapons and support systems. This technology has been very successfully transferred within the industry itself to civilian air- craft. At present, however, DoD exhibits little interest in hydrogen- fueled aircraft, probably because of world-wide logistics problems with hydrogen and the difficulty of designing a high-performance hydrogen- fueled fighter." It would be awkward to fuel jet transports on hydrogen but jet fighters on conventional fuel because that would require a paral- lel fuel system. Should the DoD not decide to fly hydrogen-fueled air- craft for any mission, then the manufacturers' cost of development of a 269 PAGENO="0473" 467 civilian airplane would-rise since there would be no appreciable tech- nology transfer. This would be an important consequence for the future of hydrogen-fueled civilian aviation. 3. Airport Operators Major airports in the United States are publicly owned and operated by municipal or regional governments with the exception of National and Dulles in and near Washington D.C., which are operated by the FAA. Local governments usually regard operation of a modern, efficient airport as a necessity to retain (and attract) industry and commerce in the region. Airport construction is usually financed through the issue of revenue bonds, backed in part by the anticipation of landing fee receipts collected from the airlines. Fuel is usually dispensed at airports by one or a few suppli- ers bound by contract to the airport operator who acts as a fuel broker with the airlines. Since the investment in fuel dispensing facilities is large, the fuel suppliers usually obtain `evergreen' contracts--that -is, they are normally renewable provided performance is adequate. Air- ports therefore have a clear interest in the fuel used by th~ aircraft because this affects their relationships with both the airlines and fuel suppliers, and affects their physical plant as well. In addition, air- ports must be concerned about the personal safety of airport personnel, travelers, and the security of the expensive aircraft crowded together. Airport operators, to a certain extent at least, are respon- sive to the concerns of the neighboring public--especially with respect to noise. Increasingly outspoken criticism of airport noise by residents and businesses near airports'2"3 has led airport operators to issue noise abatement operating procedures. These dictate aircraft operations during taxiing and pre-takeoff engine run-up as well as during and just 270 PAGENO="0474" 468 after takeoff. In some cities major lawsuits by airport neighbors against airport operators have led to the purchase and demolition of nearby residential areas to create noise buffer zones around the air- port (Los Angeles International is a good example of this). Alterna- tively, some airports, such as National Airport in Washington, D.C., have established night and morning curfews on airport operations to lessen aircraft noise problems. These actions by airport operators illustrate the pressure airports can exert on airlines and fuel sup- pliers, through which they can have a major influence on certain as- pects of aircraft operations. 4. Fuel Producers and Distributors Fuel producers and distributors naturally play a major role in the aircraft system configuration. As long as the fuel remains un- changed--as it has for the last two generations of aircraft--their role remains rather passive, but should a shift in fuel become a serious possibility, their role will become active and they will constitute perhaps the most important decision element in the system. As noted previously in Table 7-1, the weight of the liquid hydrogen fuel carried by a 400-passenger subsonic passenger aircraft with a range of 3000 nautical miles would be about 28,000 lbs--or 14 tons.14 This amounts to about one quarter of the daily output of the largest (60 ton) liquid hydrogen facility ever built. As Table 12-1 shows, the projected hydrogen liquefaction building block of 250 tons/ day would be able to fuel about 18 aircraft per day and would use about 60 percent of the daily output of a nuclear/electrolysis building block. 271 PAGENO="0475" 469 Because it `is not economically feasible to convert a commer- cial* airplane from conventional jet fuel to hydrogen,15 whatever fuel is chosen for the next generation of aircraft will have to be in reason- ably certain supply for the lifetime of the airplane. Since design and certification of a new airplane takes 6 to 10 years, and the airplane generally remains in service for about 20 years, the fuel chosen must be available for about 20 years following the delivery of the last air- plane in the production run. Thus, if in 1985 a firm decision is made for delivery in 1995 of a new generation of airplanes that uses conven- tional petroleum-based jet fuel, and if the airplane remains in produc- tion for ten years (until 2005), then jet fuel must remain available until about 2025. In other words, a 1985 decision must be viable for about 40 years. This exceeds the normal planning horizon of most cor- porations. As domestic petroleum supplies become increasingly scarce, airlines will naturally want assurance that they will continue to be able to obtain fuel before making a commitment to another generation of petroleum-based conventional jet-fueled aircraft. Moreover, the air- `lines are unlikely to forget that during the Arab oil embargo in the winter of 1973-74 they received disproportionately small fuel alloca- tions apparently because the government judged that air travel was less essential1 to national welfare than other uses of petroleum--including automobiles. As a result, airlines and aircraft manufacturers are just beginning to give some attention to the aircraft fuel of the future. *As distinct from a unique demonstration airplane. jOr, politically less controversial. 272 PAGENO="0476" 470 In spite of their experience during the Arab oil embargo, elements of the aviation industry often articulate the point of view that the absolute need for a portable high-energy density fuel is so nearly unique to aviation that aviation should be given the highest priority for petroleum fuels. However, since they recognize that such priority may not be politically feasible, their next favored alternative is the production of synthetic jet fuel from coal or oil shale, because this places all of the burden of accomplishing the change outside the aviation industry onto the shoulders of the petroleum companies. Clearly, therefore, fuel producers and distributors will play a central role in any possible switch of aviation over to hydrogen. 5. Government Regulatory Agencies In general, the role of the Federal Aviation Administration (FAA), would be expected to be more direct and to begin at an earlier date than the CAB. The primary responsibilities of the FAA (established in 1958) are the establishment and maintenance of U.S. airways (includ- ing enroute, terminal and final approach navigational aids), airport development (a program of financial assistance), pilot and aircraft certification, setting and enforcing safety standards for manufacture and operation, and research and development (mainly related to safety, such as for all-weather instrument landings) *16 The first involvement of the FAA in the airworthiness certif i- cation of new aircraft occurs a month or so after the first sales are concluded and it is decided to go ahead with detailed development of the conceptual design.'7 Since the first sales are based on only tentative designs, the FAA participates from the start in assuring that safety standards are met. The aircraft manufacturers give great attention to this interaction with the FAA because the FAA must certify that an air- plane class is airworthy before deliveries can be made to airlines.17 273 PAGENO="0477" 471 The manufacturers are guided by existing Federal Aviation Regulations (FARs) but if a particular situation is not covered because a novel approach or technology is being planned, the FAA will issue "special conditions" as a supplement to the relevant FARs.17 Regula- tions are couched in terms of a functional capability. To meet special conditions, the burden of proof is on the manufacturer, and on its own volition or at the request of the FAA, there may be special experimental verifications of any new technology before it can be incorporated into the design.1? Because the stakes are high, the relationship between the manufacturers and FAA representatives is very close during the en- tire design period. Indeed, the FAA representatives are permanently assigned to a particular manufacturer and have offices on the premises. Likewise, manufacturers have special staff assigned permanently to the task of providing FAA liaison.17 In the past, the aviation state-of-the-art has been mainly advanced by military development* and proved by military experience; this has been reflected not only in the manufacturers' design approach but in the airworthiness standards as well. However, a hydrogen-fueled commercial aircraft may not have been preceded by military experience. Thus, whether the design state-of-the-art will represent levels of safety comparable to those achieved by a similar hydrocarbon-fueled aircraft is uncertain. A further, and perhaps more important, question is whether the aircraft certification process would accept the existing technology or would require that it be advanced. Of course the actual safety of an aircraft is always demon- strated in practice. The many factors that contribute to accidents, such as pilot proficiency, weather conditions, aircraft maintenance, *With some contributions from NASA in close coordination with DoD. 274 PAGENO="0478" 472 operation and availability of navigation aids, and aircraft design limi- tations or malfunctions, are investigated by the National Transportation Safety Board (NTSB). Since circumstances often interact to cause an accident, an unequivocal determination of design inadequacy is not always possible. Nevertheless, the operating experience of an aircraft feeds back in an important way to affect design modifications. The most seri- ous of the original design inadequacies result in an airworthiness direc- tive to owners that specifies a mandatory retrofitted change. An air- craft may even be withdrawn from service until the modification is made. There is no numerical standard for aircraft safety in terms of injuries or fatalities per million passenger miles. However, whenever a series of accidents occurs, Congressional hearings usually follow quickly. These hearings can be considered a bellwether of public opin- ion and, together with the NTSB crash investigations, have usually led to changes of practice or design that have resulted in acceptably safe aircraft. Several alternative strategies can be defined regarding the safety of hydrogen-fueled aircraft: * Develop a state-of-the-art aircraft and depend on the initial operating period to provide actuarial data on safety and feedback on design deficiencies and opera- tional limitations. * Require the manufacturers and/or airlines to engage in an extended period of preoperational (pre-passenger) analysis and flight testing. This might be in the form of all-cargo operations that used only airports distant from population concentrations. * Fund a government program of research, development, and operational testing, including NASA, DoD, FAA, and air- frame and engine manufacturers. Basically, these alternatives represent a trade-off between a program of in-service development and testing involving the traveling public and a 275 PAGENO="0479" 473 program of extensive preoperational development and testing. This amounts to a choice between private funding, ultimately passed on to the traveling and shipping public, and direct public funding, putting the burden on taxpayers at large. Crashworthiness or passenger survivability is becoming an in- creasingly important aircraft safety issue. In many aircraft accidents, the occupants would have survived if there had been no fire. Therefore, a primary concern in crashworthiness is with post-crash fires including those involving the fuel supply. Even if hydrogen were not flammable and explosive within a wide range of hydrogen-to-air ratios, liquid hydrogen would be a dangerous material because of its extreme coldness. Concern would be warranted to ensure that an accident did not spill hydrogen on people, or so thoroughly chill an area that evacuation would be endangered. The close working relationship between the FAA and the manu- facturers essentially ensures that neither party is surprised when the final airworthiness flight tests occur.17 The close relationship, how- ever, is subject to the criticism often raised against regulatory agencies--there is a significant danger that the welfare of the manu- facturer will be given more weight than the welfare of the public. Nevertheless, the effectiveness of safety regulation is demonstrated by the falling death rate per distance traveled, shown in Table 15-2, in spite of increasing traffic and airport congestion. Noise standards have historically been administered by the FAA, and under pressure of the FAR Part 36,18 the noise characteristics of new aircraft are greatly improved over their predecessors5 as shown in Figure 15-3. Recently, however, to be consistent with its jurisdiction 276 PAGENO="0480" 474 Table 15-2 DOMESTIC AIR TRAVEL BY SCHEDULED AIR CARRIERS: STATISTICS Category Aircraft in operation* Average available seats per aircraft Revenue miles flown (millions) Revenue passengers carried (millions) Fata litiest Passenger fatalities per 100 million miles flown z a. Ui -j z & LU LU U) 0 z SOURCE: Refe~ence 5 1950 1960 1970 1972 1220 1867 2390 2347 38 66 110 118 370 821 2028 2000 17 56 153 172 109 363 1 185 1.2 0.9 -- 0.13 FIGURE 15-3. PROGRESS IN TAKEOFF NOISE REDUCTION Source: Statistical Abstract of the United States, 1974. *Excludes helicopters. flncludes crew members. 125 - 120 - 115 110 DC-8-61 - *DC-8-63 105 100 95 90 - 1954 DC-8-20 7208 S 727-100 I I I I I I i 1956 1958 1960 1962 1964 1966 1968 * DC-b-b boll YEAR 970 1972 1974 277 PAGENO="0481" 475 over other noise sources,19* the EPA has been given strong jurisdiction over the area of aircraft noise. The EPA may propose noise regulations to the FAA which is bound to publish them and either adopt them or state reasons why not within a fixed period of time. It is safe to assume that a government agency will be involved in aircraft noise regulations whenever hydrogen aircraft might begin service. The most common and fairly sophisticated tool of aircraft and airport noise management is the Noise Exposure Forecast (NEF) *18 ~ The weighted factors that influence NEF ratings are * Absolute noise level * Noise frequency spectrum * Maximum tone * Noise duration * Aircraft type * Mix of aircraft * Number of operations * Runway utilization * Flight path * Operating procedures * Time of day A hypothetical NEF 30 contour for a particular mix of aircraft is shown in Figure 15-4. The NEF 30 contour is particularly significant because it corresponds to the boundary within which land use for residential purposes is normally considered unacceptable.2° *This move has resulted in interagency jurisdictional rivalry that will surely be resolved before a hydrogen-fueled aircraft design begins. 278 62-332 0 - 76 - 31 PAGENO="0482" 476 REPRESENTATiVE LARGE AIRPORT 119701 COMMERCIAL NUMBER OF AIRCRAFT TYPE OPERATIONSIDAY 9727-100, B737. DC-B 140 20 6727-200 40 9707. 9720, DC-B 106 I I C DC-B (Stretched) 10 6747 (PAd, Bodyl 6 - Propel),, AirorsIl 54 10 - 10 - NEF 20 CONTOURS ~ TAKEOFF ~ DISTANCE TO THRESHOLD - 1000 ft DISTANCE FROM BRAKE RELEASE - 1000 ft SOURCE: Adopted from Reference IS FIGURE 15-4. NEF CONTOURS FOR A REPRESENTATIVE SINGLE-RUNWAY AIRPORT IN 970 Each individual airplane operating at a particular airport has its own noise contour or `footprint." The NEF contours for an air- *port are the weighted sum of all the contours of the airplanes using the airport taking into account all the other factors listed above.21 Since the scale employed in the addition is logarithmic (based on the decibel scale, dB), the noisiest aircraft dominate the composite NEF contour. As Figure 15-3 showed, the oldest aircraft are the noisiest and, since these are generally the first to be replaced, introduction of any new aircraft will tend to reduce the area within the NEF 30 contour (unless an increased number of operations offsets the improvement in the indi- vidual airplanes) ~22 Air pollutant emissions also come under the regulatory author- ity of the EPA. The clean burning aspects of the hydrogen-fueled air- plane could conceivably lead EPA to increase the stringency of aircraft 279 PAGENO="0483" 477 emissions standards until use of hydrogen became the best alternative to controlling emissions available to the aviation industry. However, recent experience with the relaxation of the timetable for automotive emissions clean-up because of claimed hardship on the part of the auto- motive industry makes it doubtful that emissions standards will be made that strict. Several agencies of government play important roles in the aviation system. The Civil Aeronautics Board (CAB) established in 1938, regulates the rates, routes, service entry/abandonment, and mergers for the 43 scheduled and nonscheduled interstate airlines.16 The CAB also regulates U.S. operations of international airlines. A similar role is played for intrastate airlines by various public utilities commissions in the relevant states. The CAB would become a participant in a change of aircraft fuel indirectly through its rate setting capacity in the event that a differ- ential in fuel cost affected the revenue and profitability of airlines. The CAB would play a more direct role when the existence (or absence) of hydrogen fuel facilities affected the viability of the route structure of regulated airlines. Since the mission of the CAB is both to protect the consumer interest of the traveling public and to foster a healthy and vigorous air travel system, it would be concerned whether a transition to hydrogen might unduly alter the competitive position of an airline with poor access to hydrogen. B. Transition to Hydrogen To achieve a transition from the present petroleum based aircraft fuel to hydrogen would be a major undertaking, and the risks for all the stakeholders would be major. Yet, as indicated above, in the aviation sector the number of decision-makers involved is far fewer than in the 280 PAGENO="0484" 478 automotive sector and this will tend to facilitate the decision-making process. Moreover, as also indicated by the discussions above, the stakeholders have a long tradition of close cooperation and highly coor- dinated decision-making. Consequently, it is probable that if a hydrogen economy were to be realized aviation would be the sector involving mer- chant* hydrogen most likely to make the first large-scale significant shift. Deliveries of the next generation of subsonic passenger airplanes may not occur before l99O-2OOO.~ In the introduction of any technology that requires an infrastructure--such as the aviation fuel production and distribution networks--there is a difficult period of coordination reminiscent of the query of whether the chicken or the egg came first. Systems that are familiar today and that require vast infrastructures were introduced slowly and incrementally as demand grew from nearly zero. The transition to hydrogen-fueled airplanes would have to be much more rapid to justify economic participation by most of the major parties having an interest. Consequently, a nearly unprecedented coordination of effort would be required.~ An implementation plan can be envisioned in which the airplane man- ufacturers, the airlines, the fuel suppliers, and the government coordi- nated efforts to make aircraft and fuel available at essentially the *Hydrogen not used on an entirely captive basis such as for electric utility load leveling. fBecause the newer jets use improved materials and construction tech- niques, unlike the early jet planes, they have no definite lifetime determined by structural fatigue. As a result, the historical periodi- city in the turnover of airplane fleets may have been broken. Unless compelling advances in the aviation state-of-the-art occur to motivate replacement, the present generation of wide-body aircraft could continue in service to 1990 or beyond. 281 PAGENO="0485" 479 same time. A planned implementation schedule could probably enable the hydrogen-fueled system to supplant most of the long-haul jet-fueled sys- tem within a decade once deliveries began. The scenario might proceed as follows: * In 1975 public and private discussions about the transition might begin. * In 1980 the decision to produce both an airplane (perhaps selected in a government competition) and fuel would be made. * In 1995 the first liquid-hydrogen-fueled aircraft would be delivered to airlines, and fuel would be available at four of the most separated major air travel hubs, probably, New York, Washington, D.C., San Francisco, and Los Angeles. * Between 1995 and 2000 one new airport could be added to the network every six months within the United States, and f a- cilities for fueling would be installed at major overseas airports, such as London, Amsterdam, Frankfurt, and Rome, thereby enabling the first international flights. No attempt need be made to drive the transition to completion, for when the transition had been started, there would be strong incentive for all parties involved to convert the trunk lines to hydrogen as quickly as possible to avoid unnecessary costs from duplicated facilities. It is not likely that feeder airlines would be in a position to use hydro- gen, but they could await development of a smaller airplane with suffici- ent hydrogen-carrying capacity to enable loop routes to serve small air- ports for which provision of liquid hydrogen would be uneconomic. Insight into the feasibility of a transition to a hydrogen-fueled commercial aviation industry is aided by examination of the size of the required system elements and comparison with the natural building blocks. The top five air travel hubs (New York, Los Angeles, Chicago, San Fran- cisco, and Atlanta) account for about 36 percent of the national passen- ger total, and the top 25 airports account for about 74 percent.1 As an example, San Francisco International Airport (SF0) is considered in 282 PAGENO="0486" 480 Table 15-3, where it can also be seen that the costs of completely switching the fuel supply and distribution system of even a single air- port over to hydrogen are very large. Although most of the costs shown in Table 15-3 would have to be borne by the fuel suppliers, these costs greatly exceed the total expenditures of $1.3 billion in 1971 by fed- eral, state, and local governments on airport expansion or alteration. The large size of these investments will surely result in the exercise of great caution in approaching a decision about hydrogen-fueled aviation. To add perspective to the investment needs established in Table 15-3, the investment that would be required to produce a synthetic crude oil suitable to produce synthetic hydrocarbon jet fuel (identical to that now used) from coal and oil shale would be in the range of $500-700 mil- lion 1973 dollars* for a 100,000 barrel per day plant.23'24 This is based on the 1973 jet fuel usage at SF0, which averaged 40,000 barrels per day,25 and assumes that existing refineries would process the coal or oil shale synthetic crude oil and that existing distribution pipelines could be used.26 The major reason why the synthetic crude oil approach to providing aviation fuel proves less costly is that much of the exist- ing fuel processing system would remain useful, while the nuclear! electrolysis hydrogen system would require a fresh start. The lower investment cost for synthetic jet fuel compared with that for liquid hydrogen naturally raises the question of why the hydrogen option should be entertained at all. The answer, quite obviously, lies *Plant construction costs are estimates since no actual commercial sized plant has been built or contracted. As Figure 11-1 showed, the plant construction index has escalated far more rapidly than other indices in recent years. Thus, recent news items cite significantly higher costs in current dollars. However, the same escalations would affect the investments cited in Table 15-3. 283 PAGENO="0487" Table 15-3 AIRPORT LIQUID HYDROGEN SYSTEM (SAN FRANCISCO INTERNATIONAL 1973 USE RATES) Number of Average Hydrogen Building Unit Total Energy Flow of Blocks Capital Capital Supply of Demand Component Building Block (GW)* Required ($ millions) ($ millions) Fuel demand 2.5 Fuel system Fuel supply options Nuclear/electrolysis 0.53 5 Nuclear power plants 1.0 5 560 2800 Electrolytic plants -- -- 34 170 Coal gasification 1.5 2 l4O~ 280 Hydrogen gas pipeline (30-inch diameter) 2.7 1 Depends on distance Liquefaction facility 0.32 8 22.5 180 Totals Nuclear option 3150 Coal gasification option, excluding pipeline 630 *See Table 12-1. jSee Linde's estimate, Table 11-4. PAGENO="0488" 482 in the finite nature of the coal and oil shale resources--ultimately these resources will decline in accessibility and a transition to another source of fuel would be required. However, U.S. shale and coal reserves will last for a century or considerably longer,* depending on the total growth of energy consumption in the United States,27 future accessibil- ity of domestic and foreign crude oil, and the extent that coal resources are developed for other uses (e.g., coal gasification, liquefaction, and electric generation). Given that someday a change will probably be nec- essary, the basic question facing aviation is the choice of the most propitious time to invest in a change. The various stakeholders are likely to hold conflicting opinions about the desirability of the transition. The major concerns of the various stakeholders regarding a hydrogen-fueled aviation sector will probably be the following: * Airlines - Economics of all facets - Public acceptance (safety) - Assurance of fuel supply * Aircraft manufacturers (without government subsidy) - Added costs of development - Effect on foreign sales * Airport operators - Costs of airport alteration - Safety to people at the airport - Noise levels - Air pollution emissions *But, since many foreign countries do not have such large reserves of nonpetroleum hydrocarbons, U.S. aircraft makers might respond to their needs. 285 PAGENO="0489" 483 * Fuel producers and distributors - Relative investment requirements and profitability of hydrogen compared to other fuel supply alternatives - Protection of still-valuable investments in the hydro- carbon fuel system - Ability to assure customers of supplies * Federal Aviation Administration - Safety of the fuel in the aircraft and as well as during fueling - Noise levels * Civil Aeronautics Board - Airline financial health - Cost of air travel * Environmental Protection Agency - Noise levels - Air pollution improvements * Federal government in general - Energy policy effects of hydrogen in aviation - Balance of trade effects of fuel and aircraft. These concerns would probably lead to the following grouping, according to degree of enthusiasm for hydrogen in aviation: * Most enthusiastic (in descending order) - Hydrogen producers* - EPA - Aircraft manufacturers - Airlines *But probably only if they are not also producers of conventional jet fuels. 286 PAGENO="0490" 484 * Basically neutral - FAA - CAB - Airport operators * Least enthusiastic - Fuel producers (conventional fuels) Before these lines are drawn even as firmly as the above categorization would imply, considerable hardware research and development must be achieved to alleviate some major uncertainties in the practicality (as opposed to feasibility) of hydrogen-fueled aircraft,14 and systems stud- ies performed to indicate how the transition would have to be phased to prove successful. Because the military is apparently not supporting any significant R&D in hydrogen-fueled aviation,11 and because aircraft man- ufacturers cannot afford it in the amounts needed, governmental R&D funding appears to be a necessary prerequisite for reaching the point where the hard, potentially expensive, decisions can be made on rational bases. Whether the aviation component of implementation schedule scenarios depicted in Figure 13-1 through 13-4 comes to pass depends crucially on the new information generated and the perspective gained in the next decade. C. Impacts Although it cannot be foreseen whether a confluence of events will actually result in the introduction of hydrogen-fueled commercial avia- tion near the end of this century, the rest of this chapter discusses the impacts of the hypothesized transition. 287 PAGENO="0491" 485 1. Economic Efficient utilization of the large capital investment in air- planes is essential to profitable airline operation. Since planes can generate revenue only when they are flying, the airlines try to minimize maintenance and turnaround times. The key is to have adequate ground facilities to handle schedule peaks. Clearly, the introduction of liq- uid hydrogen at airports would have to be coordinated with the advent of the hydrogen plane. The large investments in each element of the avia- tion system would be expensive to bear if one element were forced to remain idle while waiting for the other to be deployed. The transition to hydrogen aircraft would differ from the introduction of new genera- tions in the past: A totally new infrastructure would be required for fueling. The fuel system from production through distribution would have to be deployed. The lead times for the fuel system would equal or exceed plane development time, especially for the nuclear-based option. From an airline viewpoint, the coordination problem might be overwhelming since the airline would not be likely to have control over either the fuel or the aircraft end of the situation. The airlines would be open to great risks if forced to pay for one part of the sys- tem while waiting for the other parts. Other factors that affect the airlines' decision to purchase new aircraft are the used aircraft market, the depreciated value of ex- isting fleets, and the availability of capital. Because of the short depreciation periods taken by the airlines for tax purposes, the exist- ing fleets are seldom physically "worn out' by the time enough deprecia- tion allowances have been accumulated to afford replacement.9* The *However, for rate-setting purposes the CAB allows a depreciation based on the expected time to technological obsolescence.3° 288 PAGENO="0492" 486 used aircraft market will depend greatly on the world-wide availability and price of liquid hydrocarbon fuels. If the emergence of hydrogen- fueled aircraft were attendant on an absolute, worsening shortage of hydrocarbon fuels in the United States, the domestic market for used hydrocarbon-fueled aircraft would be poor, but if hydrogen-fueled air- craft represented a response to a policy of national energy independence while ample supplies of foreign petroleum still remained, the market for used aircraft would not be affected much. The two aircraft depreciation rates controlled by the Internal Revenue Service (IRS) and the CAB are strong factors in the ability of airlines to generate internal funds and to show a profit. Naturally, the ability to attract external capi- tal depends largely on the profitability of an airline. Accelerated depreciation of new hydrogen-fueled aircraft is a potential governmental policy mechanism by which an airline could generate profits and attract external capital, both of which could be used for the acquisition of new aircraft. The financing of airport facilities is related to the airlines financial situation. Currently, state and local authorities issue rev- enue bonds based partly on landing and use fees collected from the air- lines. Therefore, the feasibility of issuing such bonds (as well as their interest rate) ultimately depends on the financial capability of the airlines. Moreover, at some airports, notably O'Hare in Chicago, airlines agree to underwrite residual costs (i.e., after all revenues from concessions, parking, etc., have been collected).3° Table 7-I showed that the initial purchase price for a hydrogen-fueled airplane is expected to be essentially identical to that of an advanced jet-fueled airplane, but the energy utilization, measured on an energy per seat-mile basis, is expected to be lower (about 5 to 10 percent) ~ Thus an airline could presumably afford to 289 PAGENO="0493" 487 pay a slight premium for hydrogen fuel and still come out even with a jet-fueled plane.'4 Two other key factors of economic importance will be the turn- around time of the aircraft at an airport and the reliability and main- tenance schedule. Since the time for refueling apparently is not the pacing factor in aircraft turnaround today, unless hydrogen refueling proved to be significantly slower, this aspect should pose no direct problem. However, it has been suggested, presumably to enhance safety and lessen the delivery costs for liquid hydrogen, that liquid hydrogen airplanes should refuel and undergo between-flight cabin refurbishing at a central "island" removed from the airport terminal. This system is currently in use at Dulles International near Washington, D.C., where passengers are shuttled between the terminal28 and the airplanes in large special vans.28 If this procedure proved a necessity rather than an option, the average turnaround time at airports might be increased, thereby adversely affecting the aircraft utilization factor. Whether this system would increase or decrease costs of airport modification is unclear. Maintenance of hydrogen-fueled aircraft engines, should be simpler and less frequent than for jet-fueled engines because th~ fact that hydrogen mixes so quickly and completely with air and burns so cleanly allows use of a simpler combustion chamber.29 These character- istics also result in lower maximum local temperatures (about l800°K compared with 3000°K) and allow the use of less exotic materials29 and reduced engine wear. The maintenance of liquid hydrogen fuel storage and delivery systems in the airplane, however, may be more frequent (at least initially) and more complex than for conventional jet fuel systems.14 The challenge of designing fuel systems with maintenance intervals com- petitive with conventional jet fuel systems can probably be met. 290 PAGENO="0494" 488 A key constraining force on airlines embarking on the use of hydrogen would come from the complex system of aircraft routing employed. Seldom is an airplane merely shuttled back and forth indefinitely along a fixed route. Airlines seek to optimize their passenger load-factors and equipment utilization to remain profitable. Considerations of trav- elers preferences for time of departures and arrivals* and complications caused by differing time zones, airport curfews, aircraft maintenance schedules (relative to the location of airline maintenance bases), and rules about the length of work for air crews all necessitate the optimi- zation of the complete complex system. As a result, an individual air- plane may journey from Boston to Houston to Albuquerque to Phoenix to San Diego to Chicago to New York, with days elapsing before the cycle is begun again.30 At the beginning of a transition to hydrogen only a few air- ports could be equipped to refuel aircraftla and this would imply simple shuttle-like routing of aircraft that would result in a degree of air- craft under utilization that would affect profitability. Even as the number of airports dispensing hydrogen increased, the mix of two kinds *of aircraft in the fleet and the continual change in the mix and number of fuel dispensing locations would tend to impede optimization of equip- ment utilization. Unless the public showed great enthusiasm and pref- erence for hydrogen-fueled planes and thereby improved load factors,t it would seem natural for each individual airline to want to hold back until the pioneering with hydrogen had been accomplished by their competitors. *This varies by month, day of the week, and time of day. tLoad factors play a critical role in airline profitability.31 291 PAGENO="0495" 489 Aircraft manufacturers clearly have much at stake in the choice of whether to make a hydrogen-fueled aircraft. Their risk is much increased by the lack of R&D for hydrogen-fueled military aircraft transferrable to a civilian aviation. Historically, military aircraft led the way technologically and this enabled manufacturers to lessen the development costs for civilian aircraft. For example, much of the design for the Boeing 747 was accomplished in a military transport de- sign competition which Boeing lost to Lockheed's design of the C5-A. Nevertheless aircraft manufacturers have considerable experi- ence in liquid hydrogen technology from their work as prime contractors for space launch vehicle stages. There is question whether any single manufacturer would dare to develop a hydrogen-fueled airplane out of step with its competitors who might remain with conventional jet fuel because they anticipate development of synthetic jet fuel derived from coal and oil shale. There is no good historical analogy, for even when Boeing and Douglas took the lead introducing commercial jets, all the competitive manufac- turers had military jet experience and the military jet fuel distribu- tion network was already extensively deployed. There is room for a difference of opinion whether being first with a hydrogen airplane de- sign would yield rewards commensurate with the risk. Besides being concerned with domestic sales, the aircraft manufacturers must be very concerned about international sales pros- pects. Historically, foreign airlines have relied heavily on U.S.-made aircraft in both the new and the used markets. Conversely, U.S. air- craft producers have relied heavily on foreign sales. Table 15-4 shows the extent of this dependence. It appears that if the foreign air car- riers also switched to hydrogen-fueled aircraft, the dominance of U.S. manufacturers would not change. But if U.S. carriers were to switch 292 PAGENO="0496" 490 Table 15-4 ROLE OF COMMERCIAL AND CIVILIAN AIRCRAFT IN U.S. FOREIGN TRADE Year Category 1965 1970 1972 Aircraft, parts and accessories (value in $ millions) 1798 3053 3494 New passenger transports (number of units) 61 149 96 New cargo transports (number of units) 4 7 17 Used, rebuilt, modified, converted* (number of units) 406 358 450 *Includes changes from military to nonmilitary type. Source: Statistical Abstract of the United States, 1974. unilaterally to hydrogen-fueled aircraft, the market would be split, such that it could prove difficult for a U.S. manufacturer to make money on either a jet-fueled aircraft or a new hydrogen-fueled design, unless there were great commonality in design. Since many foreign countries are too small to justify use of long haul hydrogen-fueled airplanes domestically, and since much of their overseas traffic is to and from the United States, they might readily agree to go along with a change to hydrogen for long-haul aircraft. Sales to foreign airlines might not be necessary for produc- tion of a profitable plane, provided that fewer than three companies were competing for the domestic market,9 but the larger the market, the 293 PAGENO="0497" 491 less the risk to the manufacturer. The use of hydrogen airplanes on international routes would clearly depend on development of fuel facil- ities at major overseas airports. The question of what would induce foreign governments to move to a hydrogen fuel base for air transportation* is a subject for concern to the aircraft industry. Just as in the United States, foreign inter- ests could be expected to respond to a shortage of hydrocarbon fuels or to increasing prices of these fuels, but they would not necessarily be responsive to U.S. policy of energy independence. Instead, each nation could be expected to view its own energy policy on its own merits. Several courses of U.S. governmental policy intervention could apply pressure on foreign carriers serving the United States; for exam- ple, hydrocarbon fuel could be refused to foreign carriers, or the gov- ernment could tax hydrocarbon fuels prohibitively. Alternatively, the use of hydrocarbon fuels could be banned on the basis of pollutant emis- sion rates, much as the United States has banned supersonic flights of SSTs over populated areas because of the sonic boom. Of course, such measures might evoke retaliation, which could cripple international air transportation and cause serious diplomatic problems. Maintenance of U.S. dominance of the air transport market is a factor in the decision to produce a new airplane that might stimulate governmental intervention with subsidies or incentives. There are two underlying considerations: the balance of trade and national defense. In combination, these two considerations may result in an expressed U.S. policy to subsidize airframe manufacturers or airlines as an incentive *Such a move might create market opportunities for the U.S. nuclear power industry. 294 62-332 0 - 76 - 32 PAGENO="0498" 492 to produce a new generation of aircraft and to maintain production ca- pabilities and vitality in an industry important to national defense. Alternatively, by appealing to foreign governmental concern about their own balance of payments, the prospect of a joint hydrogen-fueled air- craft production venture night prove a very potent inducement. Employment opportunities generated by a transition to hydrogen aircraft fall into two main categories: with airplane manufacturers and fuel producers and distributors. Presumably, it will continue to be government policy to maintain a healthy aerospace industry in the inter- ests of national defense. Manufacture of aircraft and parts provided employment for 514,000 people (of which 281,000 were production workers) in 1973.32 These jobs should be relatively unchanged either in skill needs or in geographic distribution by a transition to a hydrogen-fueled aviation system. An estimated 20,000 people are engaged in the refueling of commercial aircraft. These jobs would have altered skill requirements if a transition to hydrogen occurred. The largest effect would be the transfer of jobs from the petroleum industry to the hydrogen fuel -indus- try and the basic energy resource (such as nuclear power) industry. 2. Environmental The most obvious environmental consequence of a transition to hydrogen-fueled aircraft is the reduction of emissions of air pollu- tants.14'29 The estimates shown in Table 15-5 were developed in Lock- heed's comparative evaluation of future subsonic conventional jet-fueled and hydrogen-fueled passenger transports. Hydrogen data for carbon mon- oxide, unburned hydrocarbons, and smoke are firm since the complete ab- sence of carbon compounds in liquid hydrogen precludes the possibility of their formation. The data on nitrogen oxide emissions, however, is not firm because there have been no adequate experimental measurements of- this parameter. Yet, theoretical considerations indicate that 295 PAGENO="0499" 493 Table 15-5 AIR POLLUTANT EMISSIONS COMPARISON: LH2 VS JET A SUBSONIC PASSENGER AIRCRAFT Estimated Emission Level (g/kG fuel except Emission Engine as shown)* Product Condition Jet A CO Idle 30 0 Unburned MC Idle 4 0 Smoke Takeoff 15* 0 NO Takeoff 12 x H20 Cruise 41.9 lb/nmi 82.4 lb/nmi Odors Ground Objectionable None operations *5AF 1179 smoke number. fAdjusted for the difference between the gravimetric energy densities of Jet A and hydrogen (a factor of 2.8 in favor of hydrogen). Source: Reference 14. nitrogen oxide emissions will be quite low in an engine especially de- signed for hydrogen.2~ This reduction stems both from the faster and more thorough fuel mixing and burning, which eliminates the localized hot spots most responsible for generating NO, and also from reduction of residence time in the combustor.29 The doubling of water vapor emitted from a hydrogen engine compared with that emitted from conventional jet-fueled airplanes is a relatively minor problem because in the troposphere (where subsonic jets fly) water vapor is not considered a pollutant in the usual sense. 296 PAGENO="0500" 494, However, along heavily traveled airlanes exhaust contrails (condensed water vapor) can add to cloud cover. This has been noted informally by a researcher33 at the National Center for Atmospheric Research (NCAR) in Boulder, Colorado, which is under a major east/west airlane. The pollutant emissions from subsonic aircraft while in transit make a relatively insignificant impact in overall air quality. However, air pollution from airplanes can be substantial on the ground and in the air near airports.42 When air pollution became an issue, the public was quick to note emissions of black smoke from aircraft on takeoff and, as a result, actions to eliminate most of this smoke have been completed. The emissions of vaporized fuel and unburned hydrocarbons, however, have not been completely eliminated and these are responsible for the fuel odors at airports. Although the public at large cannot readily sense the emissions of carbon monoxide and nitrogen oxides, air pollution con- trol measures have also been taken in recent years to lessen the on-the- ground emissions of these pollutants. This reduction has been accomp- lished by altering the taxiing and engine run-up patterns and operations of airplanes on the ground.34 The interaction between air pollution con- trol and noise control is important, because cutting back on the number of engines used in taxiing and the length of pre-takeoff engine run-up have reduced both irritants. Thus the positive air pollution conse- quences of hydrogen-fueled aircraft would be, by far, most pronounced at and near airports. Just as in automotive use of hydrogen, the pollutant reduction at the point of end-use is gained by creating pollution at the point of hydrogen generation. While the trade-off may be favorable from a na- tional point of view, the results would not be viewed identically in all the regions affected. Moreover, the kind of environmental pollu- tants are not necessarily measurable in commensurate terms, thereby making the trade-off more a matter for political resolution. The 297 PAGENO="0501" 495 clearest example of incommensurate pollutants is the reduction of con- ventional air pollutants gained at the expense of increasing the emis- sions and risks of nuclear power for hydrogen production. Noise is the other environmental parameter of most signif i- cance in aviation. In the Lockheed comparative evaluation of future jet-fueled and hydrogen-fueled subsonic aircraft,14 it was concluded that both kinds of future airplane would exhibit improvements over any commercial transport now flying (the quietest is the Lockheed L-loll as shown in Figurel5-3). Table 15-6 shows the estimates Lockheed obtained compared with the present applicable Federal Aviation Regulations con- cerning noise (FAR 36) ~14 As Table 15-6 shows, both kinds of airplane are expected to be significantly quieter than the L-lOll (a change of about 10 dB is equivalent to a factor of 2 in perceived noise).22 Because the NEF contours for any given airport are especially sensitive to the noisiest aircraft operations and the noisiest planes are the old first generation jets that are still in service, any new transport (using either fuel) will tend to replace the oldest jets and *thereby effect a major change in airport noise levels.22 As Table 15-6 shows, the hydrogen-fueled plane would contribute more to a noise reduc- tion in the takeoff zone but would contribute less in the landing ap- proach zone; effects in the sideline zone are nearly identical for the two kinds of airplanes. The underlying reason why a hydrogen plane would be quieter in the takeoff zone but slightly noisier in the approach zone can be traced to the relative ratios of fuel weight to aircraft empty weight (see Table 7-1) .3~ Because of the lightness of the hydrogen fuel, the gross takeoff weight of the hydrogen-fueled plane is far less than for the jet-fueled plane. This means that the engine need not be as power- ful and less energy must be expended to get the airplane airborne. Since 298 PAGENO="0502" Table 15-6 NOISE COMPARISON: L112 VS JET A SUBSONIC PASSENGER AIRCRAFT Area of Noise Levels in EPNdB 90 EPNdB FAR 36 Limits Contour Aircraft Takeoff Sideline Approach (sq mi) 3000 nmi LI!2 88.1 (103.8) 86.4 (106.3) 97.9 (106.3) 3.8 Jet A 92.7 (105.1) 86.4 (106.9) 96.6 (106.9) 4.1 5500 nmi LH2 89.2 (104.9) 87.2 (106.8) 98.4 (106.8) 4.3 Jet A 94.2 (107) 87.8 (107.6) 96.7 (107.6) 4.7 Lockheed L-1O11 (Certification tests) 96.0 (105.6) 95.0 (107) 102.8 (107) 6.6 Source: Reference 14. PAGENO="0503" 497 noise output is related to the energy expended by the engine, the noise is less. However, during descent for landing, at the end of a mission when all but emergency reserves of fuel have been exhausted, the gross landing weight of the hydrogen airplane is much nearer to its gross takeoff weight than is true of a jet-fueled plane. As a result, during descent, engines of the hydrogen-fueled airplane would have to be run at a proportionately higher power level than in a jet-fueled airplane. This accounts for the relative noise emissions of the two airplanes. It is important to note, however, that noise differences arise from differences in performance and are not intrinsic to the fuel. Thus, while a hydrogen-fueled airplane would be quieter than present airplanes, so would a future jet-fueled airplane, and the advan- tages of the hydrogen plane would be felt most in the takeoff zone. For some airports this could be a major advantage, but for other airports, where the takeoff is regularly over uninhabited areas.* there would be very little apparent advantage of a hydrogen-fueled plane with respect to noise. 3. Resource Utilization As noted earlier in this chapter, the major alternative to hydrogen in aviation in the future is the production of synthetic jet fuel from coal or oil shale. Since as noted in Chapter 11, coal is the cheapest intermediate term source of hydrogen (in the near-term, natural gas and oil remain cheaper sources), a comparison of coal resource util- ization between these two alternatives is important. Figure 15-5 which compares the relative resource utilization effectiveness of jet fuel *At Los Angeles International, for example, the very regular wind condi- tions allow takeoff over the ocean nearly all the time. 300 PAGENO="0504" 498 __________ (63%)~ (87%) (99%) ((OO%)° ~ COALJ_{Y~~ ~ to H-H o.5j~; j_~[c.Yj_r54w] (77n/,) (90%) (112%)2 ~~~j____.f_HYdrofenj_______.{ Liquefaction } ~ ~ J____._[46 ni,] ~/,I INDIVIDUAL PROCESS EFFICIENCIES [%] NET SYSTEM EFFICIENCIES FIGURE (5-5. RESOURCE UTILIZATION COMPARISON FOR SYNTHETIC JET FUEL (KEROSENE) FROM COAL AND LIQUID HYDROGEN FROM COAL (kerosene)* and hydrogen from coal, shows that either option uses the coal resource with approximately equal effectiveness. (Although the hydrogen option is shown as a little less effective, this distinction is probably not meaningful within the accuracy of the estimate.) It is important that to date the DoD shows little enthusiasm for hydrogen-fueled aircraft.11 DoD's dominance of aircraft R&D efforts make its future actions especially relevant. If DoD were to encourage the production of synthetic jet fuel from coal or oil shale, even *It is assumed that the refinery product is not restricted to kerosene alone but the usual product slate (about 6 percent kerosene) is made. Nevertheless, through an exchange of products, the production of the jet fuel can be viewed as equivalent to conversion of the synthetic crude to the single jet fuel product. 301 PAGENO="0505" 499 perhaps by direct subsidy, the synthetic liquid fuels industry would receive substantial impetus towards development. This might delay serious interest in hydrogen for commercial aviation indefinitely. DoD already has begun to examine the suitability of synthetic fuels derived from coal for meeting its needs.~6 Although it is sometimes thought that a major advantage of the conversion of aviation to hydrogen would be the release of petroleum for other uses, such as automobiles, Figure 15-5 shows that this option is really no more effective in this respect than the direct production of synthetic automotive fuels from coal.* 4. Social About one out of four Americans over 18 will fly this year. People who fly tend to be between 20 and 50 years old and to have more income and education than those who do not fly. About half the trips are taken for business and convention purposes and the other half for personal reasons of visiting and sightseeing. When people have flown, they tend to fly again and to perceive airplanes and airports as good, economically desirable, and timesavers. In 1972, the average air pas- senger took five or six trips. People who fly on business take more trips per year than people who fly for personal reasons. It seems quite possible that the demand for air travel may decrease due to increased energy prices. Additionally, the public may have a change in life- style and in values that could further decrease this demand. The energy situation that hit the American home and automobile for the first time in 1973-74 is likely to dampen the growth of both the *The efficiencies for producing jet or automotive fuel from coal are essentially the same. 302 PAGENO="0506" 500 supply and the demand for air travel, well before the turn of the cen- tury, when the first hydrogen-fueled passenger aircraft could be oper- ating. For both philosophical and economic reasons, people may seek to substitute less energy-consumptive modes of transportation for air travel. Also, by the year 2000, telecommunication of information and entertainment may compete with travel services through such devices as the videotelephone37 and cable television. The energy and oil shortages could affect the U.S. demand for air travel in less direct ways, such as through significant shifts in employment patterns, decreased employment, lower average real income, and higher real prices of commodities that will ripple outward in the economy as a result of increased energy prices. With the decline of discretionary income, proportionately fewer passengers would be able to afford personal air travel, and life-styles may shift to greater empha- sis on necessities and the lower-cost luxuries. A sentiment against air travel could even arise from an energy-conscious public, who might view energy-intensive air travel as siphoning off petroleum products from their cars. However, if the expected improved efficiency of hydrogen airplanes were realized in practice, then the public might welcome the * development--especially if it were perceived as releasing petroleum for use in the automobile. Thus, for many reasons, it is plausible to ex- pect air traffic in the United States to grow at rates considerably less than current rates and less than those that have been frequently pro- jected for the next 20 to 30 years by stakeholders in the commercial aviation sector. *Although Figure 15-5 shows that this perception could be ill-founded. 303 PAGENO="0507" 501 Noise has become recognized as a source of detrimental health effects.21'38 In fact, noise levels have been used as indicators of the quality of life in some studies. The positive health benefits de- rived from decreased aviation noise (however slight) will have the most effect on persons working in or living near airports since they have the most exposure to noise. The magnitude of this impact would increase as the transition to hydrogen aircraft becomes more pronounced. 5. Social Effects of Safety One of the major social effects of hydrogen-fueled aircraft will be the safety of individuals and groups who are involved with the aircraft either actively or passively. Early in a transition to hydro- gen aircraft it will not be possible to give proof of safety as deter- mined by airline experience. Groups with special need for concern include: * Passengers * Air crews * Ground crews * Airport operators * Airport neighbors The last three groups can be expected to view the matter with some so- phistication once adequate actual data about hydrogen safety in aviation has been accumulated. Therefore, the discrepancy between the perceived and the actual safety of hydrogen can be expected to be least for these three groups. Nevertheless, air crews and ground crews will have to be trained and informed about the relative hazards of hydrogen, and the ramifications for their own and passenger safety in the event of a mal- function. These groups will have to be convinced of the safety of 304 PAGENO="0508" 502 handling hydrogen-fueled aircraft since they will be directly encounter- ing the potential hazards that exist. If these groups are not convinced of the safety of hydrogen, they may attempt to block implementation through associations and labor unions. In addition, emergency service crews (such as airport fire departments) will require special training to cover the new hazards associated with hydrogen. During the early stages of transition, special precautions would probably be required until a large amount of experience was accrued. Passengers, however, without having the opportunity or need to be trained in the safe handling of hydrogen, would probably view the safety of the hydrogen aircraft less realistically than the crew oper- ating it. Yet, being more educated and younger than the average citi- zen, the airline passenger might know something about the new fuel, maybe even enough to convince himself that the level of risk is accept- able. Probably, however, the passenger will not squarely face whatever facts are available at the time on his chances for arriving safely at his destination. Instead, today's average airline passenger accepts risks to safety with a sense of fatality. It has been found that few passengers want to see the cockpit, for example, because it reminds them of the fallibility of the human beings piloting the airplane.39 Just as the passenger prefers not to know directly the risks of flying, or the precautions taken to reduce those risks, neither does the airline make explicit reference to its safety records when adver- tising. Instead of using data of the type given in Table 15-7 in their advertising,40 airlines prefer to use "prestige" advertising as a way of building up the image of their airline as sound, safe, and reliable. Airlines may not be able to avoid public attention to the safety issue once hydrogen-fueled aircraft have been introduced. Most people are likely to rely on their friends and acquaintances rather 305 PAGENO="0509" 503 Table 15-7 DEATH RATES FROM TRANSPORTATION ACCIDENTS Fatalities per Travel Mode 100_Million Passenger Miles Airlines 0.10 Motor buses 0.08 Railroad 0.56 Automobiles 1.9 Source: Reference 40 than on experts for verification of the real safety hazards. The spread of erroneous information could easily be started by news media linkage of hydrogen-fueled aircraft with the Hindenburg and with other disas- ters, especially since the action-filled movie in the "disaster" genre, Hindenburg (to be released in 1975),41 will have become an "old" film suitable for frequent showing on television by the 1990s when hydrogen- fueled airplanes might be introduced. Environmental action groups, while lauding the clean air and noise reduction aspects of the hydrogen airplane on the one hand, may take exception to the coal or nuclear power source of hydrogen on the other hand and choose to deprecate hydrogen's safety as an argument against airport expansions. This could strike a responsive chord in the general populace because with the aircraft flying overhead the po- tential would exist for anyone to be exposed to the hazards. It seems likely that introduction of a hydrogen-fueled airplane would have to be accompanied with a widespread education program to alleviate public apprehension. Such a program must be planned very carefully to ensure against the possibility of its backfiring through the spread of incom- plete information or information that does not take pains to address any misleading material that may be presented in the disaster movie. 306 PAGENO="0510" 504 Residents near airports would have special concern over the safety of the aircraft. Because of their location, they are confronted daily with the realities of low flying and noise and air pollution from aircraft. Naturally, they tend to have more concern than the public in general over the possibility of a crash occurring within their neighbor- hood. The introduction of hydrogen-fueled aircraft would probably stim- ulate complaints from airport neighbors. Partly because it represented a change, they may look on it as an opportunity to reiterate their dis- satisfaction with life near the airport. This fear on the part of the residents near airports has ramifications for their perception of the noise from a hydrogen plane. Although, as shown in Table 15-6, the actual noise exposure from hydrogen aircraft would be less, research has shown that tolerance to noise levels is related to individual feelings about airports. Sociological inter- view techniques were applied in a study of the noise problems in 22 U.S. communities near military airfields.38'42 Individuals who not only deemed the air base to be important and considerate, but also expressed little fear about aircraft crashes, tolerated four times the daily noise exposure before complaining as individuals who were both fearful and also had negative feelings about the air base and its importance. A study of civilian aircraft noise revealed that, of eight factors contributing to annoyance by noise, the most important was "fear of aircraft crashing in the neighborhood. "~ ,~ Even though with hydrogen-fueled airplanes the actual noise level would decrease, nearby residents might still react to their apprehension by complaining about noise. Thus it is also likely that the number of noise complaints would decrease as experience proved the hydrogen aircraft safe. 307 PAGENO="0511" 505 6. Technology The development of hydrogen-related technologies suited for use in aviation would have a spin-off to other possible hydrogen-using sectors. The large fuel demands of aviation would provide substantial stimulus to advancements in the state-of-the-art in * Hydrogen production * Distribution in liquid form * Cryogenic storage. Thus, although in principle, the aviation sector could be the only sec- tor to use hydrogen, the effects of its use would probably spread out- ward and enhance the likelihood that other sectors wou].d also ultimately embrace hydrogen. D. Governmental Role A hydrogen-fueled aviation system appears to make a great deal of sense, although many technical, institutional, social, environmental, and economic issues need to be understood more clearly before private or public decisions to support a hydrogen-based commercial aviation industry would be justified. Indeed, some of the nontechnical issues may prove to be critical bottlenecks. In general, however, the prospects for switching aviation to hydrogen seem much better than those for switching automobiles, especially since the decision-making process would be more focused and the implementation could be more easily pro- grammed. The magnitude of the development work needed before a transition to hydrogen-fueled aviation could begin appears to be beyond the capa- bilities for internal sponsorship by the aerospace industry. Moreover, the risks of such sponsorship are great because the questions that must be faced in anticipation of deployment require an unprecedented degree 308 PAGENO="0512" 506 of coordination among the various stakeholders--with a very uneven dis- tribution of economic and political power among them. Recognizing the difference between a decision to explore the option and a decision to deploy the option, the federal government's leadership and sponsorship appears to be needed to address some of the R&D questions and to explore the feasibility and possible strategies of implementation. Such strategies must clearly recognize the perceptions and needs of the various stakeholders. Only the government appears capable of initiating the dialogue in a serious fashion since the other stakeholders are likely to remain snagged on the chicken or egg" dilemma because of the economic risks involved. The federal government's interest in the possibility of hydrogen- fueled aviation would be found along several lines: * Air pollution * Noise abatement * Safety * Cost of travel (rate setting) * Energy resource utilization * Airworthiness * Balance of trade. The absence of previous significant government expenditures for hydrogen- fueled military aircraft means that the usual indirect--but very real-- subsidy of commercial aircraft is lacking. Accordingly, an economic risk mitigation or financing arrangement similar to that initiated for the supersonic transport might be warranted should studies demonstrate that deployment of hydrogen-fueled commercial aircraft is desirable. 309 PAGENO="0513" 507 E. Summary There are many complex economic, institutional, social, and envi- ronmental consequences of a transition to hydrogen-fueled commercial aviation. Table 15-8 summarizes some of these. 310 62-332 0 - 76 - 33 PAGENO="0514" 508 Table 15-8 SUMMARY OF IMPACTS OF HYDROGEN-FUELED AIRCRAFT Impact Class Economic S takeholders Nature of Effect Magnitude of Impact (units) Social Air travel demand Passengers Airlines Aircraft industry Competing transpor- tation or Effort by energy- conscious travelers to find lower energy consumption options to reduce cost Moderate (people, Investment required for production and distribution of hydrogen fuel Cryogenic Airports Oil companies Utilities Capital market tal to supplant system Vying for roles in system Investment re- quired to produce a new class of aircraft Airframe manufacturers Airlines Subsystem manufacturers Cryogenic industry Large demand for capital to develop system Cost of aircraft fuel maintenance, and repair Airlines Air passengers Personal and business travel possibly re- stricted by higher Institutional Regulatory Aircraft industry Government regulatory bodies Component producers Airline Pilots Expanded regulatory authority over de- sign criteria for performance and safety of operation Ownership of fuel system Airports Public energy utilities Oil industry Pipeline companies Cryogenic industry Competition for con- trol of hydrogen fuel markets Land use Developers Conservationists Nuclear plant builders Municipalities Competition for use of land in vicinity of airport for new fuel supply system Major (S) Major (S) Moderate ($, people) Major (power) Moderate (power) Major (power, S) 311 PAGENO="0515" 509 Table 15-8 (concluded) Impact Class Stakeholders Skilled workers Construction workers Cryogenic engineers Nuclear power industry Coal gasification industry Airport noise Airport neighbors Airports Air and ground crews Airports Airlines Passengers Airport neighbors General public Magnitude of Impact Nature of Effect (units) Employment ava i labi 1- ity in aircraft pro- duction, airport construction, power coal and hydrogen industries Transitory rise in Moderate (people) complaints that are fear-induced, fol- lowed by long-term Public attention to air Major (people, $) craft safety; Opposition to airport growth Environmental Air pollution Airport neighbors Public at large EPA Noise Trade -off Airport neighbors Airlines Airport operators Public at large Regional interests EPA Greatly reduced air pollution at point of energy consumption Reduced noise, espe- cially in the takeoff Shifting of pollution from point of use to point of production Moderate (people, $) Moderate (power, people) Governments 1 National defense Public at large National defense! Public at large Balance of trade Maintenance of strong aerospace industry Shift from foreign energy supplies to domestic sources Major (power, $) Major (power, $) Employment Moderate (people) Safety 312 PAGENO="0516" 510 REFERENCES 1. "The Long Range Needs of Aviation," a report of the Aviation Ad- visory Commission, Washington, D.C. (January 1973). 2. "FAA Statistical Handbook of Aviation, Calendar Year 1973," Federal Aviation Administration, U.S. Department of Transportation, Wash- ington, D.C. 3. "Cyclical Aircraft Introduction May Slow," Aviation Week and Space Technology (28 October 1974), p. 42. 4. "Next Generation Transports Will Emphasize Fuel Savings," Aviation Week and Space Technology (28 October 1974), pp. 48-51. 5. J. E. Steiner, "The Technology and Economics of Commercial Airplane Design--Part I," presented to the Swedish Academy of Aeronautics and Astronautics, Stockholm, Sweden, 8 November 1972. 6. 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Mann et al., "Aircraft Noise Impact: Planning Guidelines for Local Agencies," Department of Housing and Urban Development (November 1972). 21. C. R. Bragdon, Noise Pollution (University of Pennsylvania Press, Philadelphia, Pennsylvania, 1971). 22. Dr.James Young, Stanford Research Institute, Menlo Park, California (personal communication). 23. F. H. Kant et al., "Feasibility Study of Alternative Fuels for Automotive Transportation," Vol. I: Executive Summary; Vol. II: Technical Section; Vol. III: Appendices, a report by Exxon Re- search and Engineering Company, Linden, New Jersey, for the U.S. Environmental Protection Agency (June 1974). S 314 PAGENO="0518" 512 24. .1. Pangborn and J. Gillis, "Alternative Fuels for Automotive Transportation--A Feasibility Study," Vol. I: Executive Summary; Vol. II: Technical Section; Vol. III: Appendices, by the Insti- tute of Gas Technology, Chicago, Illinois, for the U.S. Environ- mental Protection Agency (June 1974). 25. Mr. William V. Paizis, Airports Commission, City and County of San Francisco (personal communication). 26. E. Dickson et al., "Impacts of Synthetic Liquid Fuel Development for the Automotive Market," by Stanford Research Institute, Menlo Park, California, for the Energy Research and Development Adminis- tration, Washington, D.C. (report in preparation). 27. "U.S. Energy Prospects: An Engineering Viewpoint," a report pre- pared by the Task Force on Energy of the National Academy of Engi- neering, Washington, D.C. (1974). 28. J. E. Johnson, "The Economics of Liquid Hydrogen Supply for Air Transportation," in Advances in Cryogenic Engineering, K. D. Timmer- haus, ed. (Plenum Press, New York, 1974). pp. 12-22. 29. A. Fern and A. Agnone, "The Jet Engine Design That Can Drastically Reduce Oxides of Nitrogen," paper No. 74-160, presented at the American Institute of Aeronautics, 12th Aerospace Sciences Meeting, Washington, D.C., 30 January-l February 1974. 30. Mr. James Gorham, Stanford Research Institute, Menlo Park, Cali- fornia (personal communication). 31. L. J. Carter, "Airlines: Half-Empty Planes Keep Profits Low, Waste," Science (24 May 1974), pp. 881-884. 32. Statistical Abstract of the United States, 1974 (Bureau of the Census, U.S. Department of Commerce, July 1974). 33. Dr. James Lodge, National Center for Atmospheric Research, Boulder, Colorado (personal communication in 1970). 34. P. Martin and V. Salmon, "South Florida Airport Site Selection Study: Document Aircraft and High Speed Ground Transport Noise and Pollution Impact Factors," Stanford Research Institute Project MSH 1181-957, Menlo Park, California (July 1971). 315 PAGENO="0519" 513 35. Mr. G. Daniel Brewer, Lockheed California Company, Burbank, Cali- fornia (personal communication). 36. R. L. Goen et al., "Synthetic Petroleum for Department of Defense Use," by Stanford Research Institute for the Defense Advanced Research Projects Agency and Air Force Aero Propulsion Laboratory, Wright Patterson Air Force Base, Ohio, Technical Report AFAPG-74-l15 (November 1974). 37. E. Dickson and R. Bowers, The Video Telephone, Impact of a New Era in Telecommunications (Praeger Publishers, New York, 1974). 38. K. D. Kryter, The Effects of Noise on Man (Academic Press, New York 1970). 39. E. Dicter, Handbook of Consumer Motivation (McGraw Hill Book Company, New York, N.Y., 1964). 40. "Air Transport Facts and Figures 1973," Air Transport Association of American, Washington, D.C. (1973). 41. "Hindenburg' Dirigible Will Fly Again (but only on silver screen)," Palo Alto Times (23 August 1974), p. 14 (Associated Press). 42. P. N. Borsky, "Community Reactions to Air Force Noise. I. Basic Concepts and Preliminary Methodology. II. Data on Community Studies and Their Interpretation," Report TR 60-689 (II), National Opinion Research Center, University of Chicago, Chicago, Illinois (1961). 43. TRACOR, "Community Reaction to Airport Noise," final report, TRACOR Company, Austin, Texas (1970). 316 PAGENO="0520" 514 CHAPTER 16--UTILITIES A. Introduction Three classes of energy utilities can be expected to play an impor- tant role in a hydrogen economy: * Gas * Electric * Combined electric and gas. A utility is an unusual form of enterprise because it is a monopoly countenanced by the law and the public. Moreover, it is a "natural" monopoly in the sense that it is impractical, both logistically and economically, for two utilities to offer the same services in any given area. To prevent the abuse of monopoly power, regulatory commissions have been established to control the utilities.1 Most large utilities are private enterprise, but there are some large government-owned util- ities, such as the Tennessee Valley Authority and the Bonneville Power Administration, and numerous municipally-owned utilities. Regulatory commissions at the state and federal level have power to control the rates utilities charge customers.1 These regulatory bodies are generally called public utilities commissions at the state level. At the federal level, the Federal Power Commission (FPC) is concerned with the interstate movement of gas and electric power. To change rates, a utility must petition the relevant regulatory commission and justify the proposed rate change* in public hearings.1 Such hearings *Usually an increase in the usual inflationary economy. 317 PAGENO="0521" 515 are often slow and long-delayed in starting.2'3 The regulatory commis- sions also have jurisdiction over facilities siting. The rates utilities charge customers are determined according to a "rate-base" formula that allows a utility a certain maximum percentage return on its capital investment;' the range is normally 7 to 9 percent. In practice, the utility definition of "capital investment" is somewhat different than in other industries. In particular, some items, such as interest paid during construction of a facility, that other industries might treat as an expense are considered capital investment by utilities because plant cost is not figured into the rate base until it becomes operational. Utilities, being natural monopolies, have certain understood obli- gations to the public.' First, they must remain financially healthy because their services are essential to public welfare and no alter- natives to their service are immediately available. Consequently, the regulatory commissions are concerned not only with the direct consumer welfare but also with the indirect consumer welfare as manifested in the health of utility industry. Second, in return for protected status as a natural monopoly, utilities have historically been obligated to serve all applicants, to provide nondiscriminatory service, and to re- frain from interfering with the nature of the consumers' use of services (unless, of course, the use posed a threat to the integrity of the dis- tribution system). For example, electric utilities have been obligated to provide electric jower whenever and in whatever quantities customers decided (and without warning) .~ However, because of the large number of customers served, these uncertainties in demand tend to average out thereby making instantaneous response manageable. Nevertheless, utili- ties are required to maintain a certain degree of ready reserve to meet statistically rare peak demands.2'4 318 PAGENO="0522" 516 Since utilities have long been regulated natural monopolies with a fairly steady rate of return on investment, their securities (stocks and bonds) are often regarded as safe, "blue chip" investments.a* Moreover, this same steady, sure business has enabled utilities to attract capital especially effectively because the risks to investors have been low. The nature of the heavy equipment involved and their ability to attract capital have led utilities to become the most capital-intensive large industry in the United States. Energy utilities accounted for about 11 percent of all U.S. business capital investment in the decade 1961- l97l.~ A reduction in utility profitability and ability to attract capital has taken place in recent years and this has become a matter of grave public policy concern.2'5 The rising costs of utility construction (at a rate that exceeds the general rate of inflation--see Figure 11-1), and the soaring costs (interest) of borrowed money have left utilities unable to attract all the capital they require to add facilities to meet in- creasing consumer demands for energy.2'5 Moreover, the diminishing sup- ply of natural gas and the rising costs of oil and coal, have eroded the *profitability of utilities as their costs rose much faster than their service rates could follow. This has been exacerbated because the con- sumer outcry over utility rate increases has greatly extended the ap- proval process, thereby increasing the lag between rising costs and recovery through rate increases.3 There have been other changes from the historical norm for utili- ties as well. The diminished availability of natural gas, for example, has also tempered the utilities requirement to serve all potential ~Recent declines in profitability and skipped dividends have tarnished this image, however. 319 PAGENO="0523" 517 customers; in some service areas, gas utilities have been allowed to refuse to connect newly constructed buildings into the service network. Hydrogen's future role in the utilities affects several of these new conditions in important ways: * A transition to hydrogen would enable gas utilities to deliver indefinitely a gaseous energy carrier to consumers.6 * Hydrogen could be a cost-effective way for electric utilities to store energy, thereby avoiding the need for some new and expensive generating~ capacity .~ * Hydrogenfacilities will be themselves capital-intensive, thereby continuing the problem of capital attraction. The impacts of a hydrogen economy on the three classes of utilities would be diverse and far-reaching. B. Gas Utilities 1. Structure and Stakeholders The natural gas industry is composed of a number of stake- holders with the utility providing only the final link between produc- tion and the consumer. The major institutional stakeholders are the following: * Gas companies that produce gas as their main business. * Oil companies, which produce gas as a byproduct of oil production. * Gas transmission pipeline companies. * Gas utilities. * Governmental regulatory agencies. The relationship of these stakeholders is shown in Figure 16-1. Oil companies generally regard gas production as a sideline and sell most of the byproduct gas produced (some is used in their own 320 PAGENO="0524" FIGURE 16-I. STAKEHOLDERS IN THE GAS INDUSTRY operations) rather than become involved in gas delivery to consumers. Gas companies regard natural gas production as their main business and explore and develop potential natural gas fields; any liquid byproducts are considered a sideline. Historically, pipeline companies have been operated as the transportation mode to convey gas from the region of production to the utilities for distribution to final consumers. Pipe- line companies are often owned jointly by several producing companies or utilities. Gas is sold to the pipeline company as it enters the pipeline and then sold to the utility as it exits the pipeline. Thus, natural gas pipelines differ from other forms of public transportation carriers (such as railroads) because they own the commodity conveyed. As domestic natural gas production declines, trunk pipelines are becom- ing underutilized. But, since there is little wear on these pipelines, they will last for many more years and the pipeline companies are, ac- cordingly, concerned with keeping the pipelines operating at full PRODUCTION 518 TRANSMISSION DISTR IBUTION ~1 I FEDERAL POWER I ~ _i r------_ ------` I FEDERAL POWER L COMMISSION [PUBLIC UTILITIES I COMMISSION 321 PAGENO="0525" 519 capacity to maintain the profitability of their investments. As a re- sult, much of the recent interest in coal gasification to produce syn- thetic methane (SNG) has been shown by pipeline companies. For example, El Paso Natural Gas Company, a pipeline company, is committed to build a large coal gasification plant in the "four corners" region of New Mexico.7 Gas utilities serve many customers all around the nation. There are several classes of service, but the most important distinctions are between "firm" and "interruptible" contracts.9,1° Customers with firm contracts have the highest priority for gas supplies, while deliv- eries to interruptible customers can be curtailed during peak demand periods if supplies fall below demand.9'1° In return for accepting the risk of interruption on short warning, these customers pay lower rates (as little as 10 percent*) than firm customers.11 Residential and most commercial use is in the firm category, while much industrial use is in the interruptible category.1° When gas supplies were abundant, the dif- ference in risk between these classes of service was more theoretical than actual because interruptions were rare. In practice, the distinc- tion usually proved to be merely a means to provide large industrial users with lower priced gas. Recently, however, the risks of curtail- ment have been real and widespread interruptions have occurred.9"° Now, many industrial users are reconsidering the trade-off s involved in their choice of fuel. *Testimony of John Sawhiil, former Administrator of the Federal Energy Administration, in Reference 11. 322 PAGENO="0526" 520 2. Consumers The geographic distribution of gas consumers is shown in Ta- ble 16-1 by class of service. Comparison of the gas pipelines shown in Figure 6-1 (Chapter 6) and Table 16-1 leads to several observations: First, total gas consumption is highest in the regions nearest its pro- duction (especially in the Gulf Coast region) and in the highly popu- lated, industrialized Appalachian/Mid-Atlantic and Great Lakes regions. It is noteworthy, however, that in the latter regions resi- dential use greatly exceeds use of the industrial type (the sum of "firm" industrial and nonutility interruptible). Second, industrial use in the Gulf Coast gas producing states is exceptionally high, show- ing that when natural gas is exceptionally available (and relatively cheap compared with other fuels) it is the choice industrial fuel. Third, the total use of gas in electric power generation is about 17 percent of the total consumption. Fourth, industrial use (`firm" industrial plus nonutility interruptible) accounts for about 43 percent of all gas consumption (but accounts for only 0.4 percent of all cus- tomers). Fifth, if the disproportionate industrial use in the Gulf *Coast region were reduced to a level similar to industrial use in other regions, and if all natural gas used to generate electric power were eliminated, there would be an effective extension of natural gas re- serves by about 30 percent.* This is largely the reason behind the federal energy policy to displace natural gas from under electric util- ity boilers10 and from industries that could use other fuels. Sixth, residential and commercial use currently accounts for about 34 percent gas saved 2700 + (2100 + 1500) *Data from Table 16-1: = = 30% total gas used 21000 323 PAGENO="0527" Table 16-1 U.S. GAS CONSUMPTION BY REGION AND CLASS OF SERVICE, 1973 (Billions (lOs) of cubic feet at 1000 Btu per cubic foot at 14.73 psia) Source: Reference 8 UI. total (cxci. field use) New England~ Appalachian/Mid- Atlantic~ Southeast Great Lakes4 Northern Plains4 Mid-Continent4 Gulf Coast4 Rocky Mountain4 Pacific Southwest4 Pacific Northwest4 Pacific4 Other than utility power generation. Totals may not add because of data rounding. 2800 1400 21000 18 11 270 280 250 3800 520 130 1600 270 130 3000 200 60 990 250 160 1500 310 500 6500 180 18 580 600 120 2500 C.Y( 150 6.7 350 -- -- 74 4New England Appalachian/Mid-Atlantic Southeast Great Lakes Northern Plains Mid-Continent Connecticut Delaware Alabama Illinois Iowa Kansas Maine District of Columbia Florida Indiana Minnesota Missouri Massachusetts Kentucky Georgia Michigan Nebraska Oklahoma New Hampshire Maryland North Carolina Wisconsin North Dakota Rhode Island New Jersey South Carolina South Dakota Vermont New York Tennessee Pacific Northwest Pacific Gulf Coast Rocky Mountain Pacific Southwest Idaho Alaska Arkansas Colorado Arizona Oregon Hawaii Louisiana Montana California Washington Mississippi Utah Nevada Texas Wyoming New Mexico 4900 140 Firm Utility Power Generation Residential Commercial Industrial Firm Interruptihle Interruptible* Other Totalt 2300 6200 2100 55 36 -- 1500 6.2 1500 610 270 160 1100 55 260 130 320 130 440 203 180 110 730 260 69 44 100 17 120 300 130 120 90 62 33 160 4.7 180 160 280 230 3300 1500 320 40 17 46 210 120 500 83 2.5 0.2 Ohio Pennsylvania Virginia West Virginia PAGENO="0528" 522 of all use but would account for about 50 percent if the conditions of number five immediately above pertained. Since the natural gas users generally most able to convert to alternative fuels (such as coal) are industries and electric utilities and those least able to convert are residences and small commercial es- tablishments, the remaining natural gas supplies will probably be allo- cated by federal policy according to the following curtailment pri- 10 11* orities * Highest - Residential - Commercial * Intermediate - Ammonia producers - Petrochemical industry * Least - Industrial heat - Electric utility heat. 3. Electric Power Generation Thus, on the face of it, the likely places to expect hydrogen first as a natural gas replacement would seem to be in electric genera- tion and industrial uses. On closer consideration, however, the pros- pects for burning hydrogen to generate electricity (except in load leveling discussed later in this chapter) are very slim because if the hydrogen were obtained by thermochemical or electrolytic processes in the first place this would prove a circuitous and inefficient way to *See Appendix A for details of the current curtailment priorities. 325 PAGENO="0529" 523 generate electricity for delivery to final demand. Only if the hydrogen were obtained from coal gasification would its use to make electricity make much sense. Moreover, because the coal could be burned directly by the utility after a suitable (even though costly) plant conversion, the choice of hydrogen would, in reality, represent a decision to transport the energy content of coal by gas pipeline rather than as solid coal in a train. Alternatively, it could represent a deliberate approach to air pollution control.* Thus, it must be concluded that the application of gaseous hydrogen is more likely in industry than in electrical generation. 4. Industrial Use Use of natural gas in industry in 1968 is shown in Figure 16-2, which shows that about 63 percent of all natural gas consumed by industry is used to make process steam and only about 30 percent is used in direct heat applications.12 Much of the process steam is low temperature steam. Since virtually any alternative energy form (electricity, coal, oil, solar, etc.) could generate process steam, to capture this part of the market, hydrogen would have to prove cheaper (on a unit energy basis),' more convenient, or cleaner. However, as discussed in Chapter 11, since hydrogen is a secondary or derived energy form, it is unlikely to be cheaper than alternatives for a very long time. If hydrogen were avail- able today, in many instances it would prove more convenient and less *Utilities are showing interest in shipping coal by rail or slurry pipe- line to the utility for onsite gasification to a low heating value mix- ture of carbon monoxide, hydrogen and (noncombustible) nitrogen. The gas is then consumed with improved thermal efficiency in an adjacent electrical generation plant that employs an advanced combined-cycle system. Besides the gain in thermal efficiency, the ability to isolate and control most of the air pollutant emissions of coal at the gasifi- cation plant instead of at the power plant is attractive. 326 62-332 0 - 76 - 34 PAGENO="0530" 524 * DOES NOT INCLUDE NATURAL GAS USED TO GENERATE ELECTRICITY IN UTILITIES SOURCE: Reference 12 FIGURE 16-2. INDUSTRIAL USE OF NATURAL GAS 1968 (Numbers in Parentheses are Quantities in Trillions [lO~2] of Btu) costly to convert equipment from natural gas combustion to hydrogen com- bustion rather than to switch to other fuels. But delays inherent in making such a large transition will ensure that hydrogen cannot be made generally available to industry for many years. Consequently, conver- sions are likely to be made to other energy forms long before hydrogen becomes a realistic choice for industry. In future time frames, hydro- gem's most potent competitor would be electricity because it is a clean, reliable, and versatile energy source. Realistically, therefore, hydrogen's future as an energy form f or steam generation in industry seems restricted to applications re- quiring very high temperature steam. As discussed in Chapter 7, the combustion product of hydrogen is steam (water vapor). Moreover, if hydrogen is burned in an atmosphere of pure oxygen, the resultant steam can have a very high temperature and be exceedingly free of contaminants. Doubtless, there are many applications where the burning of a gaseous fuel is the most straightforward manner to apply direct heat. Hydrogen's chances of capturing this market would appear to be excellent 327 PAGENO="0531" 525 unless other heating approaches (such as induction or microwave) had already become the accepted norm in the interim between the near-term reduction in the industrial use of natural gas and the long-term poten- tial use of hydrogen. 5. Barriers and Impacts There are important logistical barriers to the delivery of hydrogen to industrial markets as long as the residential and commercial markets remain on natural gas. First, the two separate (but often paral- lel) delivery systems would have to be operated. This implies added capital and operating expense compared to a single system. Moreover, with two separate systems, economies of scale could not be realized as fully as with a single larger system. This adds substantially to the already strong arguments in favor of the gas utilities embracing SNG rather than hydrogen. Second, with the industrial and residential! commercial uses disengaged in the gas system, the shape of the daily, weekly, and annual load profiles would change. Presumably, with the implied loss of diversity in end-uses, the load profiles of both the hydrogen and natural gas portions of the utility would exhibit more accentuated peaks and valleys than is now the case. This, in turn, would imply the need for additional capital expenditures to ensure the delivery of peak load gas supplies. There are important applications of these logistical and f i- nancial barriers to the delivery of hydrogen to industrial users but methane to residential and commercial users. First, there would be a strong incentive to avoid the introduction of hydrogen at all, but if it were introduced, the awkwardness and penalties of a dual system 328 PAGENO="0532" 526 would provide an equally strong incentive to complete the transition and also shift residential and commercial users to hydrogen.* This total conversion would be a step that utilities could not take lightly, for in addition to requiring a change on the part of every consumer (his appliances, probably his gas meter, leak-tightening his pipes, etc.),6 there would be a large expense incurred in upgrading and testing the large and dispersed distribution network that serves resi- dential areas. In 1973, there were about 40 million residential cus- tomers and over 600,000 miles of gas distribution mains in the United States.13 The labor needed to convert the high capacity system that serves concentrated industrial users would be small compared to the labor needed to convert the dispersed low capacity system that serves residential areas. Figure 6-1 and Table 16-1 together suggest that as methane becomes less available, its distribution would tend to be retrenched to those areas closest to production or where consumption is already the largest. Moreover, since intrastate gas is not regulated by the FPC and is now sold at much higher rates than interstate gas,t there is strong incentive for producers and pipeline companies to retain and sell the gas in the state of origin.14 Once established, this pattern of gas buying and selling will tend to resist quick change. Thus, it can be concluded that it is in the northern portion of the western United States *The only exceptions would appear to be those where large new heavy in- dustry parks were established with a large new gaseous hydrogen supply separate from the other system from the very beginning. f This situation is a subject of much public policy debate and the regu- lated price of interstate gas is expected to be increased.14 329 PAGENO="0533" 527 where gas utilities mighf first have to seriously contemplate a change to hydrogen.* - The availability of hydrogen or natural gas on a local or region~l basis would affect industry decisions about the location of~ new plants, or the relocation or marginal plants. If hydrogen were to be perceived as the fuel of the future by industrialists and were com- petitively priced, its availability would probably serve as a regional attractant. But, if, as seems most likely, the~ price of hydrogen were not coffipetitive with alternative energy forms such as coal or electric- ity, the conversion to hydrogen in a region would probably repel indus- try to areas where energy was cheaper. There are historical analogs. For example, since World War II, labor-intensive textile manufaōturing migrated from New England and the Mid-Atlanti~~ states to the southeast because labor was cheaper there. In the future, energy-intensive indus- tries can be expected to seriously contemplate similar moves based on regional energy prices. For companies with marginal operations swept up involuntarily ii~ a -enversion, and for whom there -were no intrinsic bdnef its in hydrogen, the expense of conversion might mean ruin. Besides the larger, institutional, considerations of a transi- tion to hydrogen, there would be impacts on the personal level. About 40 million households (about 60 percent of all those in the United States) are supplied with natural gas.1~ At the residential level-, most gas meters and all gas burners would require conversion (see Chapter 7) to operate on hydrogen.6 Even if performed on a neighborhood-by- *There are important external variables, however. First, the delivery of natural gas from Alaska15 could either come via a trans-Canadian pipeline for delivery into this area, or in the form of LNG brought by tankers to western ports. Second, there is a good possibility that LNG will be imported to the West Coast from Siberia. 330 PAGENO="0534" 528 neighborhood basis, this process implies that a very large number of people would be inconvenienced. On this basis alone, it seems certain that many individual citizens and/or citizen lobbies would oppose a transition to hydrogen. Yet, with careful planning this impact could probably be managed quite well. There have been recent experiences of similar large-scale conversions (e.g., England's conversion from coal gas to North Sea natural gas over the last few years) that while incon- venient, proved more a topic for conversation than a topic of serious complaint. During the period of transition when some localities were served by hydrogen at the residential level while others were served with natural gas, the mobility of citizens seeking to move from one city to another would be somewhat impaired because their gas burning appli- ances would require reconversion whenever they changed kinds of gas serv- ice territory. This limitation is mainly related to stoves, and to a much lesser extent, gas clothes dryers. However, stoves are frequently left behind with the house (often because they are built-in), and with the apartment because the stove is normally provided with the dwelling. Consequently, this possible restraint on mobility should not prove.a very serious handicap. For safety, hydrogen used in residences would require the addition of an odorant and a colorant to make leaking gas detectable by smell and flames detectable by sight (see Chapter 8) *6 During the period of transition, when individuals were least experienced with using hydrogen, safety hazards arising from incaution would probably be the greatest. Thus, it is during this period of transition that maximum attention would have to be given to public information about hydrogen. In summary, although at first sight it would seem that a con- version of gas utilities to hydrogen might be a natural first step 331 PAGENO="0535" 529 towards a hydrogen economy, the extremely large numbers of residential customers, the expected priority of allocations for natural gas,'° and the expected barriers to industrial conversion all suggest that the gas utilities will strongly prefer synthetic methane (SNG) to conversion to hydrogen. As will be seen in the next section, the prospects for hydro- gen use (captively) in electric utilities seems a much more attractive and realistic prospect. C. Electric Utilities 1. Structure and Stakeholders The structure of the electric power industry is very different from that of the gas industry and electric utility problems and oppor- tunities are also very different. The major stakeholders in the elec- tric power industry are the following: * Fuel suppliers * Equipment suppliers * Electric utilities * Regulatory agencies. Until nuclear fission energy began to be used to generate electric power, utilities were fueled by either coal, oil, natural gas, or utilized hydropower. Generation equipment is supplied mainly by several large companies--especially General Electric and Westinghouse. Because the large equipment suppliers also carried most of the burden of R&D for the electric utility industry, it is not surprising that these same companies are the dominant suppliers of nuclear power plants. It has become increasingly common for electric utilities to become interconnected in a large "grid" and as a means to lessen the problems of meeting variations in demand and to sell spare power to one another whenever it is available. Consequently, electric utilities have 332 PAGENO="0536" 530 become increasingly interdependent. Along with the benefits of inter- connection of systems have cone some disbenef its, especially the need for increasing sophisticated system control since a "fault" or overload in one utility can propagate a problem to other utilities in less than a second.* Thus, system stability is a major problem of the increasingly complex grid.4 Electric utilities, today face the following major problems:14 * Obtaining capital to finance new facilities. * Siting of new nuclear power plants. * Air pollution control of fossil fueled power plants. * Obtaining approval for new electric power transmission corridors. * Smoothing out the cyclical variations in demand (load-leveling). The most likely role for hydrogen within the electric utility industry is in load-leveling systems and this use would, in turn, affect the capital and power plant siting problems. Such application of hydrogen will be discussed further later in this chapter. 2. Energy Transmission A less likely, but nevertheless frequently mentioned, role for hydrogen revolves around the problems of power plant siting, transmission corridors, and air pollution control. As indicated in Chapter 7, and illustrated in Figure 7-5, electric utilities could conceivably attack all three problems at once. To avoid the problem of cleaning the air pollutants out of smoke from fossil-fueled electric generation plants, a *Such a problem was the cause of the large 1967 blackout in the north- eastern United States. 333 PAGENO="0537" 531 utility can install nuclear power plants. ~ it has become increas- ingly difficult to locate nuclear power plants near demand centers and, as a result, the electricity must be transmitted ever greater distances. Because the technology and expense of underground transmission is un- favorable, such transmission is nearly always accomplished by overhead high voltage wires strung between large steel towers. Opposition rooted in questions of land use and aesthetics, however, has made it increas- ingly difficult and time consuming for utilities to gain new overhead transmission corridors or to expand the capacity of those already in use.16 Consequently, it is often suggested that instead of transport- ing the energy in electrical form it could be transported in chemical form (i.e., gaseous hydrogen carried in pipelines).6"72° As shown in Figure 7-5, the hydrogen could either be generated directly from the nuclear heat by closed thermochemical cycles or by electrolysis of water. Once at the demand center, electricity could be regenerated either by fuel cells21'22 or by burning the hydrogen cleanly in turbines. The main advantage of this approach is that the land use and visual impacts *of underground hydrogen pipeline transmission are much less than for visually obtrusive overhead transmission towers and cables. Thus, it could prove easier to obtain transmission corridors for hydrogen pipe- lines than for electric transmission lines.16 Moreover, flexibility in power plant siting might be gained. There is disagreement in the hydrogen economy literature about the distance at which energy transmission in the form of hydrogen is cheaper than electrical transmission.2325 Two competing claims are shown in Figures 16-3 and 16-4. In any event, it is apparent that the distance in question is large--400 miles or more. Thus, this plan has economic merit mainly for moving power very long distances. However, as noted in Chapter 7, and illustrated by the building blocks in 334 PAGENO="0538" DISTANCE - miles SOURCE: Adapted from Reference 24 FIGURE 16-3. COST OF HYDROGEN GENERATION AND TRANSMISSION AS A FUNCTION OF DISTANCE FIGURE 16-4. RELATIVE COSTS OF TRANSMITTING HYDROGEN AND ELECTRICITY Cii WZ 0 0 ~~~GROUND ~J 500 kV 20 . ~~2OOkV LJ700kv - 345 kV HYDROGEN TRANSMISSION c 1 I I 0 200 400 600 800 1000 DISTANCE - mIles SOURCE: Adapted from Reference 25 7500 PAGENO="0539" 533 Table 12-1, a single nuclear/electrolysis unit would generate only about one third of the hydrogen flow needed to operate the smallest pipeline considered economically practical (24-inch diameter). When the lowered net efficiency of the total system--because of the extra conversion losses--is also taken into consideration, it becomes apparent that this plan has little chance of being put into practice for single nuclear power plants. However, because the building block match is much better, it does seem more attractive for large multiplant "nuclear parks" lo- cated in very distant remote areas. 3. Load-Leveling By far the most attractive use of hydrogen in utilities is in the form of load-leveling.4'2628 As noted in Chapter 7, and illustrated in Figure 7-5, this approach to load-leveling involves the use of of f- peak electric power to produce hydrogen electrolytically. The hydrogen is then stored and used to regenerate electricity in fuel cells or tur- bines when peak demands occur. By using off-peak electric power from base-loaded nuclear power, peak load power might be produced more cheaply than is possible with purchased turbine fuel.* Obviously, the value ascribed to the hydrogen must at least equal the cost of making and storing it.29 *It is important to note that the apparent low cost of this hydrogen can be merely an artifact of internal accounting methods because the utility can charge itself the incremental cost of the off-peak nuclear power used to make hydrogen. As long as the hydrogen made is reused within the utility, and indeed substitutes for a more expensive fuel for gen- erating off-peak power, the utility saves the consumer money by oper- ating more efficiently. Should, however, the utility choose to sell the hydrogen for use by other parties, then the cost of electricity used to calculate the value of the hydrogen would have to bear the full av- erage cost of power generation rather than just incremental costs. In that event, the hydrogen would cost more than alternative fuels. 336 PAGENO="0540" 534 Although Figure 7-5 showed the possibility of using liquid hydrogen for storage, the use of iron-titanium hydride beds is now widely believed to be the most feasible approach to hydrogen storage in utilities.30 The iron titanium hydride is especially well-suited to use in utility energy storage because it can be charged and discharged rapidly at pressures and temperatures near that of the hydrogen produced by commercially available electrolyzers.3° Although the same hydride would be too heavy for general use in automobiles, it would be no imped- ment in this stationary application. A key parameter in any load-leveling energy storage concept is the roundtrip efficiency of energy in and back out of storage.4 In this respect, hydrogen's major competition will most likely come from alkali metal-sulfur batteries, which are expected to be successful in a few years.~1 These batteries are expected to have a high roundtrip effici- ency and, as a result, their capital costs can be higher than can a hydrogen storage system and still break even with peak power generated with purchased turbine fuel.4 Thus, it is by no means certain that hydrogen will be the system ultimately favored by utilities for energy storage. The use of hydrogen system energy storage would have some significant direct impacts on the electric utilities but only indirectly on its customers. In particular, the utilities would experience: * Increased opportunity for utilities with no access to suitable pumped-hydro storage sites tobegin load- leveling by means of energy storage. * Increased ability to class more generating equipment as base load and thereby facilitate increased use of nuclear power.4 * Improved utilization of generating facilities, thereby improving the cost effectiveness of these large invest- ments .~ 337 PAGENO="0541" 535 * Increased system reliability by use of modular hydrogen storage systems.4 * Decreased need for `spinning reserve" as normally defined, thereby improving the economics of utility operation.4 These last two factors are important to utilities but have been seldom mentioned as advantages of hydrogen storage systems (they also appear to be advantages of battery storage systems). A basic require- ment imposed on electric utilities is that the probability of a failure be low. To achieve this, utilities have had to build a certain degree of redundancy into their systems and to keep some equipment in a state of ready reserve such that it can produce power within a few seconds of a breakdown of other equipment. This need to keep some generators ro- tating and synchronized is termed "spinning reserve."4 As an example of the extent of spinning reserve, New York state utilities are required to hold the probability of load loss to about 2.5 hours per year.4 This has been calculated to be equivalent to a 20 percent coincident reserve margin for the New York pool and requires an 18 percent margin for each company based on their own independent peak load.4 About 5 percent of the margin is classed as spinning re- serve that can assume the load in seconds. Gas turbines, which require about 5 minutes to reach full power, and pumped hydro storage facilities which requires 2 minutes, cannot be classed as spinning reserve when in a "cold" condition.4 A hydrogen-fueled fuel cell, however, would be able to reach full power in a few seconds.4* Consequently, a hydrogen based load- leveling system that also employed fuel cells would be able to cut *If an iron-titanium metal hydride storage system were unable to yield sufficient hydrogen in just a few seconds, a small store of liquid hydrogen could be held in reserve to cover the start up. 338 PAGENO="0542" 536 spinning reserve costs4 thereby improving the economics of utility oper- ation and, hence, the cost of power delivered to the consumer. It is also important in this regard that the charge/discharge portions of the hydrogen cycle need not be treated symmetrically. In particular, the storage function could be achieved at a slow rate and even sporadically while the discharge could take place very rapidly should conditions re- quire it. Since one goal of utility energy storage systems is to reduce costs, achievement of this goal would adversely affect the industries supplying utilities--especially the fuel suppliers and the electric equipment manufacturers. However, the current and expected continued shortage of energy suggests that fuel suppliers would not be adversely affected* because latent demand would absorb any slack created by the reduced utility purchases. The traditional equipment suppliers, espe- cially the manufacturers of nuclear power plants, would tend to benefit because raising the amount of power in the base load category would create more demand for nuclear power plants. Moreover, a new market for hydrogen storage and conversion equipment would arise that these *same suppliers would probably enter. 4. Load-Leveling Resource Limitations If iron titanium metal hydride storage systems were to become popular in electric utilities, there would be a major effect on the titanium industry. To store enough hydrogen to meet 2 percent of the total U.S. delivered electric power by means of hydrogen peak load- leveling devices would require a total inventory of about 1.6 x 1011 lbs *Indeed, it appears that anything that relatively painlessly reduces the total growth in fuel demand will affect fuel suppliers beneficially. 339 PAGENO="0543" 537 of titanium. In 1973, total world production of ilmenite (FeTiO3), the major titanium ore, was about 7 x lO~ lbs of which 20 percent was from the United States.13 Since about 31 percent of the weight of ilmenite is titanium, this translates to a 1973 world production of about 2 x lO~ lbs of titanium. Thus, the inventory implied for widespread use of iron titanium peak storage units is about 100,000 times as large as the pres- ent world production capacity of the metal. Titanium is the ninth most abundant element and is widely dis- tributed. The U.S. Geological Survey estimated titanium reserves as shown in Table 16_2.32 Nevertheless, a total need for 1.6 x 1011 lbs Table 16-2 ESTIMATED WORLD RESERVES* OF TITANIUM, 1970 Titanium Country (l0~ lb) United States 50 Canada 50 USSR 50 Other countries 130 Total 280 Source: Reference 32. *Reserves refer to materials in known deposits that can be extracted profitably with contemporary technology under current economic condi- tions. Resources that do not meet these criteria are, of course, larger. 340 PAGENO="0544" 538 is more than half the total estimated reserves of 2.8 x 1011 lbs32 and demand of this magnitude would necessarily spur titanium* production to the degree experienced in the past by other critical metal industries (i.e., copper, aluminum, etc.). 5. Production of Hydrogen for Sale Some have begun to mention the possibility of electric utili- ties manufacturing hydrogen with off-peak power, not for use in energy storage, but for sale instead.6'19'33'34 Like production for load- leveling, this could lead to a redefined "base load" that would facili- tate the introduction of more nuclear power plants (best operated at steady output). Whenever the available base-load power exceeded demand, the energy would simply be diverted to hydrogen production. Although this concept sounds attractive, simple calculations performed by the Public Service Electric & Gas (PSE&G) utility in New Jersey shows that the quantity of hydrogen produced in this fashion (with the present definition of base load) would only amount to one-fifth the hydrogen output obtainable from a single 1000 MWe nuclear plant dedicated to hydrogen production.28 The total energy PSE&G delivered in natural gas form was about 50 times this quantity.35 Thus, although there has been much discussion in the literature about the possibility of producing hydrogen cheaply by means of low cost off-peak electric power, the quan- tities involved would not be large enough to sustain much use of hydrogen. *It is interesting to note that the most abundant titanium-bearing min- eral, ilmenite (FeTiO3) already contains iron and titanium in the pro- portions desired. It is conceivable that hydrogen itself would be used as a reducing agent to remove the oxygen from the compound, thereby possibly greatly simplifying preparation of the iron titanium host metal substrate. 341 PAGENO="0545" 539 Besides involving only small quantities of hydrogen, the con- cept of producing hydrogen with `cheap (of the order of 2 mils per kWh) off-peak electric power appears to be based on an allocation of electric power costs that would have doubtful acceptability to regulating agen- cies. There are two ways of stating the cost of any given unit of elec- tricity produced: the incremental (or marginal) cost and the average cost. Incremental cost treats all the fixed costs of the power plant as if they were already met and as if the only pertinent charges were the fuel and operating costs; naturally, this results in a low unit cost of power.29 Average cost allocates the fixed charges of all power plant capital investment, taxes, etc., evenly over all power produced and therefore results in a higher figure.29 At present, most utilities are constrained to charge all customers a rate that does not reflect the time of day* that the power is used and thus does not reflect whether the power consumed is generated by peak load or base load equipment.~6 Thus, this rate represents the utilities average cost of producing elec- tric power by all means at its disposal, and under present circumstances utilities could not charge a lower rate for off-peak power for hydrogen production without regulatory approval.t Utility spokesmen have begun to make that point forcefully.4'29'36 A few electric utilities themselves have begun to discuss the possibility of installing nuclear capacity that considerably exceeds their base load needs with the intention of using the spare capacity *Generally, the rates can vary according to quantity of energy consumed but not according to when it is consumed. tIn any event the concept itself involves something of a paradox: once hydrogen production became routine, it would have to be viewed as just another part of the base load and thus would no longer be a candidate for special rate treatment. 342 62-332 0 - 76 - 35 PAGENO="0546" 540 to produce hydrogen for sale.28'~4 There/is a hidden presumption that the utilities would somehow charge themselves less for the electric power to electrolyze hydrogen than they would charge other customers, and thereby hydrogen would be produced at a price competitive with more traditional energy forms. However, it is questionable whether public utilities commissions would or, under public pressure, could allow this form of discriminatory pricing of electric power. Certainly, the net effect of allowing it would be that all customers of the utility involved would be subsidizing the cost of producing hydrogen. In effect, this subsidy would be passed on to the purchaser of the hydrogen. Consider- ing the increased public attention being given to utility rates and pub- lic utility commission responses, this issue of cross subsidy would cer- tainly have to be openly resolved before a utility could risk undertaking a venture that provided a hidden subsidy to hydrogen production. However, the question of the future price of off-peak power is by no means completely answered. Indeed, there is considerable discus- sion in the utility industry, by regulators, and in federal energy pol- icy circles about the abandonment of the present rate structure in favor of rates that charge the user more nearly the actual cost of the power he consumes.35 By this approach, a user would be charged more for power during peak demand periods than during slack demand periods. The goal is to stimulate energy conservation and to use the economic/institutional means of rate structures to achieve both a degree of load-leveling of utility demand and abatement of demand growth.35 The proposed rate structures would especially induce those industrial users most able, and those to whom the cost of electric power was the most significant cost of production, to shift their electric loads to slack parts of the day or week. Since the effect of this structure would be to reduce off-peak rates and to raise peak rates compared to the present norm, an 343 PAGENO="0547" 541 institutionally-approved mechanism might still arise to enable hydrogen production with cheaper off-peak power. Although there are difficult technical* and political/economic issues involved in instituting "time-of-day" pricing, some European coun- tries have made it a practice. The United States probably will also have made significant moves in this direction before a hydrogen economy makes much headway. It should be noted, moreover, that time-of-day pricing would tend to stimulate the use of electric-powered automobiles that could be recharged at night. In return, this would tend to level the utility load profile, by filling in the valleys rather than knocking off the peaks. Thus, the electric car, if satisfactorily developed, would not only give competition to a clean hydrogen-fueled car, but it would also pose an indirect threat to the generation of hydrogen with off-peak power. D. Combined Electric and Gas Utilities In many parts of the United States, gas and electric utilities are combined in one company. The hydrogen economy concept would be attrac- tive to these combined utilities because hydrogen could be used to load- level both the gas and electric systems.27 As noted in Chapter 7, be- cause of air conditioning loads, electric utilities generally experience their peak annual demands in the summer, while the gas utiliites gen- erally experience their peaks in the winter because of space heating. Gas utilities must address the problem of where to obtain suffici- ent hydrogen to allow a conversion in their service areas. Since gas utilities are mainly only involved in passing along to the consumer a *Such as metering. 344 PAGENO="0548" 542 commodity in the same form* as found in nature, in contrast to electric utilities, they have little experience in the complex technologies of energy conversion. However, in a combined utility, the gas portion of the business could turn to the electric portion for expertise, for ex- ample, in nuclear power plant operation. Thus, as far as the technical expertise is concerned, it would be easier for combined utilities to move into the use of nuclear power for hydrogen production. As the building blocks in Table 12-1 show, a single nuclear/electrolysis unit could provide enough hydrogen to sustain the residential demands of about 330,000 people. A combined utility using nuclear power would gain flexibility and a degree of inherent system redundancy that could lead to a reduction in its need to maintain costly reserve systems. This would enable the delivery of lower cost energy to consumers. For example, by dedicating some nuclear plants to electric production, some to hydrogen production, but enabling some to swing back and forth between production of the two forms of energy as the demand fluctuates, the utility would be able to use the same nuclear power plants and hydrogen storage systems to both load-level and provide.a substitute for spinning reserve (or the gaseous equivalent) for both systems. When an electric utility made hydrogen to sell in competition with the gas utility serving the same area, the gas utility could be expected to resist this competition and erosion of its status as a natural mon- opoly by complaining to the regulatory commissions. A combined utility could sidestep this kind of sticky institutional problem. *Except that an odorant is almost always added. 345 PAGENO="0549" 543 The combined utilities that did engage in hydrogen business, and the regulatory bodies that watched over them, would have to resolve the question of possible cross subsidization of services* to the satisfac- tion of the public and those who intervene in the public interest. How- ever, since telephone companies and public regulatory utilities commis- sions have long grappled with this kind of problem,1 no doubt there is a ready paradigm for solution. Since combined utilities have both technical and institutional ad- vantages compared with separate utilities for participating in a hydro- gen economy, it seems likely that the utilities that would be the first to deliver gaseous hydrogen are the combined utilities. Indeed, if the concept of a hydrogen economy gains credence and momentum, this advan- tage may stimulate mergers between separate gas and electric utilities. E. Nuclear Power--A Key Issue The use of nuclear power to generate hydrogen, or the use of hydro- gen as a means of temporary storage of energy produced by nuclear power, is a central underlying theme of this report. Indeed, nuclear power, solar energy, and coal are the three key energy sources for producing hydrogen. However, the preponderance of current thinking on the hydrogen economy concept emphasizes nuclear power to drive a combination electric/ hydrogen economy in the long term. The quantities of nuclear power im- plied for hydrogen production alone are enormous. Table 16-3 gives a rough estimate of the number of 1-GW (electric) nuclear reactor building blocks that would be needed to supply the 1973 U.S. energy demands in a *Where one service is made to pay more than its fair share of costs to allow another service to be priced less than bearing its fair share of costs would indicate. 346 PAGENO="0550" 544 few selected sectors (assuming that electrolysis is the approach to hydrogen generation). The total electric generating capacity required for a complete conversion of the aviation, automotive, and residential gas sectors (at 1973 energy demand levels) is 650 plants of l-GW (electric) each. This amount exceeds the roughly 450 GW of total in- stalled U.S. electric capacity in 1973, of which about 14 GW was nuclear (27 plants).37 Obviously using nuclear power to fuel any major aspect of the hydrogen economy would involve a massive undertaking. Table 16-3 ESTIMATED NUMBER OF NUCLEAR/ELECTROLYSIS PLANTS NEEDED FOR SELECT SECTORS* (1973 Levels of Demand) Number of Plants Sector (l-GW electric, O.53-GW 113) Aviation 40 Residential gas 340 * Automotive 270 Total (for these sectors only) 650 *See Table 12-1 for building block sizes. The costs of nuclear power plants are a subject of some contro- versy, largely because much of the discussion is imprecise in stating (by year) the value of the dollar employed. Moreover, because a nuclear power plant now takes about nine years to construct, the expenditures are not all paid with dollars of a single year's value. Consequently, 347 PAGENO="0551" 545 a discussion of nuclear power plant costs is useful background for this report. The direct capital costs of a completed plant include the price increases that occur during construction. This price escalation may add 50 percent or more to the estimated direct cost made in terms of dol- lars valued at the project's starting date. To illustrate, a nuclear plant cost estimate of $300 per kW for equipment, materials, and labor in 1973 dollars may actually incur $450 per kW for direct costs by the time construction is completed seven to ten years later.~8 Interest costs incurred during construction also add to the total installed cost. Since a utility has to finance construction costs over the construction period, the cost of such funds is properly charged to the capital cost of the asset. An excellent illustration of the capital cost estimates of nuclear power is contained in a study prepared by Arthur D. Little, Inc. for Northeast Utilities.~8 As shown in Table 16-4, this estimate explicitly breaks out cost escalation and interest during construction. In this case the total funds required for the investment are more than double the 1973 cost of labor, materials, and equipment. Even with generous allowances for contingencies, most nuclear gen- erating plants do not come on line by the scheduled completion date. The Atomic Industrial Forum (AIF) found that 70 out of 95 plants under construction or awaiting construction permits as of December 1973 had experienced delays of 2 months to 5.5 years.~9 Delays were caused primarily by design changes, and secondarily by changes in regulatory requirements and procedures. A third delaying factor was related to labor--either poor productivity or shortages of construction workers. 348 PAGENO="0552" 546 Table 16-4 CAPITAL COST ESTIMATE FOR NUCLEAR PLANT* $/kW Direct costs (1973 $) 306 Escalationt 142 Allowance for funds during construction 114 562 Use and sales tax 15 Utility costs 41 Contingency (15 percent) 84 702 *No land or fuel costs are included. jEquipment, materials, and labor are escalated at different rates. Source: Reference 38. Delays add significantly to the eventual plant cost, ~because inter- est on funds invested before the delay occurs continue to accrue. More- over, delays postpone the beginning of revenues--further aggravating the financial situation because utilities must treat interest incurred during construction as a capital investment rather than as expense. From Table 16-4 it can be seen that if there were no escalation of costs during construction, the power plant would cost $560/kW.~ Thus, the total investment (at book value in constant dollars) implied by ~Obtained by subtracting $142/kW from $702/kW in Table 16-4. 349 PAGENO="0553" 547 just the demand sectors using nuclear power to make hydrogen listed in Table 16-3 is about $360 billion (1973 dollars). As has become apparent throughout this report, the clean-burning attribute of hydrogen means that a hydrogen economy would produce less air pollution at the point of end use than the present system. Indeed, the environment would probably be generally improved in essentially every respect if hydrogen were in widespread use. The major negative environmental aspects of a hydrogen economy occur where the hydrogen is produced, and as has been seen, unless the coal gasification or solar options develop more vigorously,* this essentially translates into the negative environmental aspects of nuclear power. The negative environ- mental aspects of nuclear power have been widely discussed elsewhere and include: * Discharge of heat into the air or water (depending on the approach to cooling). * Low-level release of radionuclides during normal plant operation. * Potential accidental release of large amounts of radionuclides during fuel reprocessing and waste disposal. In addition, fundamental questions have been raised about the ability of society to safeguard the plutonium recovered from spent nuclear fission fuel to prevent its falling into the hands of criminals and terrorists.40 Public debate over nuclear power has been going on almost since World War II ended, and rather than dying down, the level of debate seems to be intensifying--not just over the present kinds of reactors but es- pecially over the breeder reactor, which would produce much more *Nuclear fusion is also a possibility, although scientific--let alone engineering and economic--feasibility has yet to be demonstrated. 350 PAGENO="0554" 548 plutonium. Although this report cannot become a treatise on the nuclear power controversy,* it is the crux of the concept of a hydrogen economy: Probably the single most critical_factor in the long-term viability of a hydrogen economy is the fate of nuclear power. Without nuclear power the hydrogen economy concept could rely on coal gasification in the short run and solar power in the long run, but the evolution of the hydrogen economy would be greatly impeded if nuclear power development is impeded. Table 16-5 gives a short schematic summary of the impacts of hydro- gen use in energy utilities. *A bibliography on the topic of nuclear power and its problems is pre- sented at the end of this chapter. 351 PAGENO="0555" Table 16-5 SUMMARY OF IMPACTS OF HYDROGEN USE IN UTILITIES Magnitude of Impact Impact Class Stakeholder Nature of Effect (units) Gas Utilities Safety Gas user Possibly decreased safety owing to proper- Moderate (people) ties of hydrogen Business Utility Continued viability as an enterprise Major ($, power) Labor Utility employees Effects on work owing to properties of Minor (people) hydrogen affecting safety Continued source of employment Moderate (people, $) Economic Utility, consumer, Increased cost of energy delivered in Moderate ($) regulatory bodies gaseous form Electric Utility Reliability Utility, consumer Improved reliability owing to modular Moderate ($) na tore of hydrogen load-leve hog storage systems Economic Utility, consumer Reduced cost of load-leveling technologies Major ($) Reduction of other, more costly forms of Major ($) spinning reserve Utility, regulatory New market possibilities for selling Moderale ($, power) agencies, consumer electrolytic hydrogen Cross subsidization Minor ($) Environment/ Utility, citizens, Increased need for nuclear power plants Very major (people, safety regulatory agencies power) PAGENO="0556" 550 Appendix A FEDERAL POWER COMMISSION PRIORITIES FOR NATURAL GAS CURTAILMENTS* Most Vulnerable Category Use Criteria Description (iO~ SCF/Day) 9 more 10,000 Industrial users with inter- 8 3000 to 10,000 ruptible contracts and boilers 7 1500 to 3000 equipped to use other fuels. 6 300 to 1500 5 more than 3000 Industrial users with firm 1500 to 3000 contracts and with boilers equipped to use other fuels. 3 All industrial users not specified in cate- gories 4 through 9. 2 Large commercial users, industrial users with firm contracts who use natural gas for a feed- stock, processing or plant protection, dis- tribution companies that store gas for peak- season use. Least Vulnerable 1 Residential and small commercial users who con- sume less than 50,000 SCF/day. *Source: Federal Power Commission and "Industry Braces for a Natural Gas Crisis," Business Week, October 19, 1974, pp. 114-117. 353 PAGENO="0557" 551 BIBLIOGRAPHY ON NUCLEAR POWER Pro and Con General 1. `U.S. Energy Prospects: An Engineering Viewpoint," a report pre- pared by the Task Force on Energy of the National Academy of Engineering, Washington, D.C. (1974) 2. D. J. Rose, "Nuclear Eclectic [sic]Power," Science (19 April 1974), pp. 351-359. 3. A. M. Weinberg, "The Short-term Nuclear Option," in Report of the Cornell Workshops on the Major Issues of a National Energy Research and Development Program, revised edition (Cornell University, Ithaca, New York, December 1973), pp. 131-167. 4. H. A. Bethe, "Advanced Nuclear Power," in Report of the Cornell Workshops on the Major Issues of a National Energy Research and Development Program, revised edition (Cornell University, Ithaca, New York, December 1973), pp. 169-2 19. 5. A. Hammond, "Fission: The Pro's and Con's of Nuclear Power," Science (13 October 1972), pp. 147-149. 6. R. Gillette, "Nuclear Power: Hard Times and a Questioning Congress," Science, Vol. 187 (21 March 1975), pp. 1058-1062. 7. A. M. Weinberg, "Social Institutions and Nuclear Energy," Science (7 July 1972), pp. 27-34. Nuclear Fuels 8. H. Mohrhauer, "Enriching Europe With the Gas Centrifuge," New Scientist (5 October 1972), pp. 12-14. 9. W. D. Metz, "Uranium Enrichment: Laser Methods Nearing Full-Scale Test," Science, Vol. 185 (16 August 1974), pp. 602-603. 354 PAGENO="0558" 552 10. W. D. Metz, "Uranium Enrichment: U.S. `One Ups' European Centrifuge Effort,' Science, Vol. 183 (29 March 1974), pp. 1270-1272. Safety and Waste Disposal 11. R. Gillette, "Nuclear Safety: Calculating the Odds of Disaster," Science, Vol. 185 (6 September 1974), pp. 838-839. 12. "The Deadly Dilemma of Nuclear Wastes," Business Week (3 March 1975), pp. 70-71. 13. R. Gillette, "Nuclear Safety: Damaged Fuel Ignites a New Debate in AEC," Science, Vol. 177 (28 July 1974), pp. 330-331. 14. A. S. Kubo and D. J. Rose, "Disposal of Nuclear Wastes," Science, Vol. 182 (21 December 1973), pp. 1205-1211. 15. R. Gillette, "Plutonium (I): Questions of Health in a New Industry," Science, Vol. 185 (20 September 1974), pp. 1027-1032; and "Plutonium (II): Watching and Waiting for Adverse Effects," Science, Vol. 185 (27 September 1974), pp. 1140-1143. International Politics and Nuclear Theft Risks 16. M. Willrich and T. B. Taylor, Nuclear Theft: Risks and Safeguards (Ballinger Publishing Company, Cambridge, Massachusetts, 1974). 17. M. Willrich, Global Politics of Nuclear Energy (Praeger Publishers, New York, 1971). 18. J. McPhee, The Curve of Binding Energy (Farrar, Straus, and Giroux, New York, 1974). Breeder Reactor 19. "Second Thoughts That Threaten the Breeder," Business Week (24 Aug- ust 1974), pp. 21-24. 20. "%~y the Breeder Program is Under Attack," Business Week (10 Novem- ber 1973), pp. 222-224. 21. G. D. Friedlander, "The Fast-Breeder Reactor: When, Where, Why, and How?" IEEE Spectrum (February 1974), pp. 85-89. 355 PAGENO="0559" 553 22. Suddenly the Gas-Cooled Breeder Looks Good," Business Week (17 Feb- ruary 1975), pp. 36B-36F. 23. J. Tinker, "Breeders: Risks Man Dare Not Run," New Scientist (1 March 1973), pp. 473-476. Fus ion 24. W. D. Metz, "Nuclear Fusion: The Next Big Step Will Be a Tokamak," Science (7 February 1975), pp. 421-423. 25. R. F. Post and F. L. Ribe, "Fusion Reactors as Future Energy Sources," Science, Vol. 186 (1 November 1974), pp. 397-407. 26. W. D. Metz, "Laser Fusion: One Milepost Passed--Millions More to Go," Science, Vol. 186 (27 December 1974), pp. 1193-1195. Offshore Siting 27. L. J. Carter, "Floating Nuclear Plants: Power from the Assembly Line," Science, Vol. 183 (15 March 1974), pp. 1063-1065. 28. "Offshore Power Plans Go Adrift," Business Week (19 October 1974), pp. 102C-lO2E. 356 PAGENO="0560" `554 REFERENCES 1. A. E~ Kahn, The Economics of Regulation, Vol. I, Principles (1970) and Vol. II, Institutional Issues (1971), (John Wiley and Sons, New York). 2. "Utilities: Weak Point in the Energy Future," Business Week (20 January 1975), pp. 46-54. 3. F. A. Ford, "A Dynamic Model of the United States Electric Industry, 1950-2010," Research Program on Technology and Public Policy, Dartmouth College, Hanover, New Hampshire, prepared for the National Science Foundation, NSF-RANN Grant No. GI-34808X. 4. H. A. Fernandes, "Hydrogen Cycle Peak-Sharing for Electric Utili- ties," 9th Intersociety Energy Conversion Engineering Conference, 1974, pp. 413-422. 5. J. E. Hass et al., Financing the Energy Industry (Ballinger Publish- ing Company, Cambridge, Massachusetts, 1974). 6. D. P. Gregory et al., "A Hydrogen-Energy System," American Gas Association, Alexandria, Virginia (August 1972). 7. "Draft Environmental Statement for the El Paso Gasification Proj- ect, San Juan County, New Mexico," prepared by the Upper Colorado Region, Bureau of Reclamation, U.S. Department of the Interior (16 July 1974). 8. "United States Gas Consumption 1973," Supplement to Volume 5 of the "Future Gas Consumption of the United States," prepared by the Future Requirements Committee, published by the Future Requirements Agency, Denver Research Institute, Denver, Colorado (September 1974). 9. "Natural Gas Users Sing a Dirge," Business Week (13 January 1975), pp. 37-40. 10. "Industry Braces for a Natural Gas Crisis," Business Week (19 Oc- tober 1974), pp. 114-117. 357 PAGENO="0561" 555 11. "Federal Power Commission Oversight--Natural Gas Curtailment Pri- orities," Committee on Commerce, United States Senate, 93rd Congress, 20 June 1974. 12. "Patterns of Energy Consumption in the United States," by Stanford Research Institute, Menlo Park, California, for the Office of Science and Technology, Executive Office of the President, Washington, D.C. (January 1972). 13. Statistical Abstract of the United States, 1974 (Bureau of the Cen- sus, U.S. Department of Commerce, July 1974). 14. "A Furious Push to Deregulate Gas," Business Week (19 May 1975), pp. 91-92. 15. "Battle Over Arctic Gas," Time (1 April 1974), pp. 20-23. 16. Mr. Raymond Huse, Public Service Electric and Gas, Newark, New Jersey (personal communication). 17. D. P. Gregory, "The Hydrogen Economy," Scientific American (Janu- ary 1973), pp. 13-21. 18. W. E. Winsche, K. C. Hoffman and F. J. Salzano, "Hydrogen: Its Future Role in the Nation's Energy Economy," Science, Vol. 180 (29 June 1973), pp. 1325-1332. 19. E. Fein, "A Hydrogen Based Energy Economy," The Futures Group, Glastonbury, Connecticut (October 1972). 20. L. T. Blank et al., "A Hydrogen Energy Carrier," Systems Design Institute, National Aeronautics and Space Administration, Johnson Space Center, Houston, Texas (1973). 21. T. H. Maugh II, "Fuel Cells: Dispersed Generation of Electricity," Science, Vol. 178 (22 December 1972), pp. l273-1274B. 22. "Fuel Cell Research Finally Paying Off," Chemical and Engineering News (7 January 1974), pp. 31-32. 23. D. P. Gregory, "A New Concept in Energy Transmission," Public Utilities Fortnightly (3 February 1972), pp. 3-11. 358 62-332 0 - 76 - 36 PAGENO="0562" 556 24. P. J. Hampson et al., "Will Hydrogen Replace Electricity?" in Hydrogen Energy Fundamentals, A Symposium-Course, T. N. Veziroglu, ed. (University of Miami, Coral Gables, Florida, March 1975), pp. S3-25--44. 25. J. M. Burger, "An Energy Utility Company's View of Hydrogen Energy," in Hydrogen Energy Fundamentals, A Symposium-Course, T. N. Veziroglu ed (University of Miami, Coral Gables, Florida, March 1975), pp. S4-39-63. 26. J. Burger et al., "Energy Storage for Utilities via Hydrogen Systems," 9th Intersociety Energy Conversion Engineering Confer- ence, 1974, pp. 428-434. 27. p. A. Lewis, "Hydrogen Use by Energy Utilities," in Proceedings of the Cornell International Symposium and Workshop on the Hydrogen Economy, S. Linke, ed. (Cornell University, Ithaca, New York, April 1975), pp. 266-273. 28. J. M. Burger, "An Energy Utility Company's View of Hydrogen Energy," in Hydrogen Energy Fundamentals, A Symposium-Course, T. N. Veziroglu, ed. (University of Miami, Coral Gables, Florida, March 1975), pp. S3-25-44. 29. 5. Law, "Cost of Off-Peak Power," in Proceedings of the Cornell International Symposium and Workshop on the Hydrogen Economy, S. Linke, ed (Cornell University, Ithaca, New York, April 1975), pp. 212-213. 30. G. Strickland et al., "An Engineering-Scale Energy Storage Reservoir of Iron-Titanium Hydride," in Hydrogen Energy, T. N. Veziroglu, ed. (Plenum Press, New York, 1975), pp. 611-620. 31. A. L. Robinson, "Energy Storage (I): Using Electricity More Efficiently," Science (17 May 1974), pp. 785-787; Part II in Science (24 May 1974), pp. 884-887. 32. D. A. Brobst and W. P. Pratt, eds., United States Mineral Resources, U.S. Geological Survey Professional Paper 820, U.S. Department of the Interior (1973). 33. H. Lotker, H. Fein and F. Salzano, "The Hydrogen Economy--A Utility Perspective," paper presented at the IEEE Winter Meeting, 1973. 359 PAGENO="0563" 557 34. M. Lotker, "Hydrogen for the Electric Utilities--Long Range Possi- bilities," 9th Intersociety Energy Conversion Engineering Confer- ence, 1974, PP. 423-427. 35. "A Concerted Push for Rate Reform," Business Week (14 April 1975), p. 66. 36. S. Law, "Electric Utility Views," in Proceedings of the Cornell International Symposium and Workshop on the Hydrogen Economy, S. Linke, ed. (Cornell University, Ithaca, New York, April 1975), p. 355-358. 37. "53rd Semi-Annual Electric Power Survey," a report of the Electric Power Survey Committee of the Edison Electric Institute, New York, New York (April 1973). 38. "A Study of Base Load Alternatives for the Northeast Utilities System," a report by Arthur D. Little, Inc., Cambridge, Massa- chusetts, to the Board of Trustees of Northeast Utilities (5 July 1973). 39. Nuclear News (July 1974), pp. 55-57. 40. M. Willrich and T. B. Taylor, Nuclear Theft: Risks and Safeguards (Ballinger Publishing Company, Cambridge, Massachusetts, 1974). 360 PAGENO="0564" 558 CHAPTER 17--STEEL-MAKING AND ANMONIA SYNTHESIS A. Introduction Steel-making and ammonia synthesis are large potential chemical uses of hydrogen. As a hydrogen economy develops, strong synergistic links should develop between energy carrier and chemical applications. As noted earlier (Chapters 7 and 12), each steel-making plant would require such large quantities of hydrogen that it would most likely be produced and used captively. Ammonia synthesis from a pure hydrogen feedstock is unlikely in this country for many years because hydrogen derived from hydrocarbons is expected to both remain cheaper and remain preferentially available to this industry. Participation of these two industries in the hydrogen economy would produce such important effects that these industries need to be singled out for special attention. B. Steel-Making 1. Use of Coal Steel produced in the United States amounts to about 20 percent of the total world production, and the industry consumes about 5 percent of all U.S. energy.1 By comparison, Japan, the third largest steel pro- ducer* makes about 80 percent as much steel as the United States, but the industry consumes about 20 percent of Japan's total energy budget.2 Steel-making consumed about 12 percent of all the world's energy in l973.~ *The production of the Soviet Union is about equal to that of the United States. 361 PAGENO="0565" 559 Steel is clearly a commodity of worldwide importance, not only because it is the basic material of industrialized society, but also because of the large proportion of world energy devoted to its manufacture. In the United States, steel-making and coal have long been associated industries. In fact, the simultaneous availability of both iron ore and coal has been the dominant factor in plant location. Iron ore is mined primarily in the region around Lake Superior, the largest of the Great Lakes. This ore is concentrated near the mine and then transported by special cargo ships on the Great Lakes to iron refining and steel producing regions. Historically, coal has been mined primarily in the Appalachian states, and this had led steel makers to concentrate in Pennsylvania, Ohio, and Indiana. Table 17-1 shows the dominance of these regions in the industry. Basic steel production employed over 600,000 people in l973.~ The linkage between steel and coal is strong because the steel industry uses coal both as a source of energy and as a chemical. Steel- making has been consuming about 20 percent of all U.S. coal productionl* and conversely coal provides more than 60 percent of the steel industry's energy needs.5 However, the chemical use of coal (transformed to coke, a hard, porous form of carbon) dominates the energy use, as shown in Table 17-2. *This percentage will fall in the future as coal is used in greater amounts to generate electric power. 362 PAGENO="0566" 560 Table 17-1 LEADING REGIONS OR STATES PRODUCING IRON ORE, BITUMINOUS COAL, AND RAW STEEL, 1972 Quantity Region (millions of tons) Iron Ore Total U.S. Production 75 Lake Superior 62 Western 11 Total these regions 73 Bituminous Coal Total U.S. Production 595 West Virginia 124 Kentucky 121 Pennsylvania 76 Illinois 66 Ohio 5]. Total these states 438 Steel* Total U.S. Production 91 Pennsylvania 20 Ohio 16 Indiana 15 Total these states 51 *As indicated by `pig" iron. Source: Statistical Abstract of the United States, 1974. 363 PAGENO="0567" 561 Table 17-2 USES OF COAL IN THE STEEL INDUSTRY, 1970 Quantity Percent of Use (106 tons) Total* Coke-making 87.0 95.0 Steam production 4.8 5.0 Miscellaneous 0.3 0.3 92.0 100.0 *Percentages do not add because of rounding. Source: Reference 1. 2. Steel-Making Processes Iron ore is an iron oxide.t The raw ore is usually concen- *trated magnetically and by physical separation processes before shipment to enrich its iron content. At the steel mill, the concentrated ore is then chemically `reduced" to remove the oxygen from the iron oxide to yield unrefined iron. In conventional iron-making this reduction is accomplished in a blast furnace. The blast furnace is charged with iron ore concentrate, coke, and a "flux" of limestone or other materials and then a stream of air is "blasted" through. The coke attracts the oxygen away from the iron oxide ore, and the flux dissolves "gangue" jThere are three possible oxides: ferrous, FeO; f~rric, Fe203; ferro- soferric, Fe304. 364 PAGENO="0568" 562 or impurities (mostly silica or alumina) to form "slag," a waste prod- uct1'6 The product of a blast furnace is raw or "pig" iron. There- after the pig iron is remelted, refined, and made into steel by con- trolled additions of small quantities of other materials. This is accomplished in either an open hearth furnace, a "basic oxygen" furnace, or an electric arc furnace. In modern practice the open hearth approach is giving way to the other two processes. The possible future role of hydrogen in steel-making lies not in its use as a fuel, but in its use as a reducing chemical reagent to replace coke (Chapter 7). The reduction of iron ore without using coke is termed "direct reduction," and most attention has been given to proc- esses that utilize a mixture of carbon monoxide (CO) and hydrogen rather than pure hydrogen as the reducing gas. This mixture is obtained from the reforming of hydrocarbons in the manner discussed in Chapter 4; methane is the preferred feedstock, even though supplies are falling. Direct reduction of iron using carbon monoxide and hydrogen takes place in the solid rather than the molten state and results in a pellitized or sponge product (95 percent iron) that can substitute for pig iron.1'7 The directly reduced iron differs from pig iron, however, because it contains more residual impurities. Use of an electric arc furnace is the preferred way to refine directly reduced iron because it can substitute for the usual charge of steel scrap in the crucible. Figure 17-1 shows the various present steel production methods in the United States and compares then with the possible future direct reduction/electric-arc furnace approach. Although the situation shown in Figure 17-1 represents direct reduction with a carbon monoxide and hydrogen mixture, reduction by pure hydrogen would involve the same sequence. 365 PAGENO="0569" 563 ~ BLAST _______TOPEN HEARTH FURNACE FURNACE _____ BA~C OXYGEN 1 ~ ,~~I*Ip.,i FIGURE 7- I. COMPARISON OF CONVENTIONAL STEEL-MAKING AND DIRECT REDUCTION APPROACH (Entire Direct Reduction Option Shown Shaded) A special study committee of the American Iron and Steel In- stitute (AISI) concluded, however, that use of pure hydrogen is less desirable than use of the gas mixture because with pure hydrogen there is a tendency for the iron particles to sinter (stick together) and to reoxidize.° Nevertheless if hydrogen were used, these processing prob- lems could almost certainly be overcome. There is now considerable discussion concerning the use of nuclear energy steel-making. First, nuclear heat would be used to reform hydrocarbons to obtain a reducing gas. Second, electricity would be generated for the electric furnace.2'6'8 If pure hydrogen were used, then nuclear energy would be used to produce it either electrolytically or by closed thermochemical cycles. Table 12-1 showed that there is a good match between a nuclear-electrolytic plant building block and a direct reduction building block if about half the nuclear plant's output is used as electricity and half is used to make hydrogen. 366 PAGENO="0570" 564 Thus, once again, the question of society's acceptance of nuclear power becomes critical in this aspect of the hydrogen economy (Chapter 16). The question is more difficult here, however, because the only U.S. built nuclear reactor presently capable of supplying the req- uisite high temperature (1650°F) is the high temperature gas cooled reactor (HTGR) made by General Atomic Company--a reactor that requires weapons-grade fuel.9 This fuel greatly exacerbates the danger of theft of nuclear materials by terrorist groups. Most current thinking about direct reduction processes con- tinues to assume the use of reformed methane. Consequently, much inter- est has been shown by foreign countries that have vast surpluses of methane--especially the Soviet Union and countries in the Middle East. Other countries also showing interest in direct reduction are those not so well endowed with natural resources as the United States. Japan is said to be especially concerned about the worsening availability of coals suitable for coking (metallurgical coal) and is quite interested in the direct reduction process.2'~'6 Yet, because the United States is still well endowed with all the traditional steel-making ingredients (iron ore, *coking, coal, and limestone), the U.S. steel industry is not pursuing direct reduction with vigor. The AISI nevertheless concluded that the potential for direct reduction warranted expanded R&D efforts in this country.6 3. Impacts The major consequences of a switch to direct reduction tech- niques would be the following1: * Reduced need for coke (about 50 percent) and therefore, in proportion, metallurgical coal. * Great reduction in the air pollution because of the reduced production of coke. 367 PAGENO="0571" 565 * Reduced production of slag and therefore, in proportion, need for flux materials, such as limestone. * Great reduction in the amounts of oxygen consumed in steel- making as the electric furnace substituted for basic oxygen furnaces. * Increased productivity (about 45 percent) since the time needed for an electric furnace cycle would be reduced from 160 minutes to 110 minutes. * Reduced need for steel scrap in steel-making. * Reduced capital investment in steel-making. * Accentuated desirability of ores with low levels of impurities. As with most technological changes, however, the most convincing driving force is economic savings. The AISI committee on direct reduction estimated that the con- ventional (nonnuclear) methane reforming approach to the direct reduc- tion/electric furnace method would require a capital investment of $80/ annual-ton compared with an investment of $130/annual-ton for the con- ventional blast furnace/basic oxygen furnace method. There would also be a reduced selling price of steel. However, if the heat for the methane reforming process were supplied by HTGR, the investment require- ment would be about $140/annual-ton; this is about 8 percent higher than the conventional approach employing blast furnaces.6 The conclusion given above that nuclear steel-making is not yet economically competi- tive is apparently contradicted, however, by a British study that con- cluded that nuclear steel-making would already be cheaper than the con- ventional approach.2* *Because of a lack of data, we are unable to reconcile these claims. 368 PAGENO="0572" 566 A key advantage of direct reduction is the elimination of much coke production because this process emits large quantities of air pollutants. Indeed, air pollution from coke ovens is, without doubt, the steel industries' major current environmental problem.5'8"°" Clearly, the need for environmentally disruptive coal mining is corres- pondingly reduced. These environmental benefits, however, are somewhat offset by the need to concentrate the raw ore more completely near the mine. This would result in increased solid waste for disposal in the mining region. However, increased concentration reduces the need for impurity-removing, slag-producing fluxes, such as limestone, thereby again reducing mining activity and also reducing slag production at the smelter. Since slag is often recycled and completely consumed as a con- struction material (road aggregate, railroad ballast, etc.) a reduction in slag is less beneficial than it would seem at first glance.' Ta- ble 17-3 summarizes the changes in quantities of inputs and outputs for carbon monoxide-hydrogen direct reduction processes. Use of pure hydro- gen for direct reduction would result in a similar table. An important consequence of direct reduction processes with environmental implications is its effect on the recycling ot scrap iron and steel. The ferrous scrap market is very volatile1 and business suc- cess in this field is elusive. Because direct reduction of iron can sub- stitute for the scrap normally used in electric furnaces, direct reduc- tion might deal the domestic market for ferrous scrap a crushing blow.1 Since steel-making consumes about 5 percent of all U.S. energy, ferrous scrap should be viewed not only a materials resource but also as a stored energy resource. In an energy-tight future, this resource should be used diligently to conserve energy and to reduce the environmental effects of energy production and consumption. Hence a reduction in the economic viability of the ferrous scrap recycling business must be viewed as detrimental. 369 PAGENO="0573" 567 Table 17-3 SUMMARY OF CHANGES EXPECTED FROM DIRECT REDUCTION/ ELECTRIC FURNACE STEEL~MAKING* Percentage Change Compared to Average Inputs and Outputs U.S. Practice in 1970 Ferrous inputs Ore - 53% Scrap ot Fuels and energy Coke (coal) - 77 Purchased electric power + 310 Natural gas +1100* Fuel oil - 100 Fluxes Limestone and dolomite - 62 Lime + 34 Fluorspar - 40 Oxygen - 51 Slag produced - 60% *Assumes conventional reforming of methane, use of carbon monoxide-hydrogen mixture as reducing gas; no use of nuclear power. tAssumes no change, although there is the possi- bility of displacing much scrap. Source: Reference 1. 370 PAGENO="0574" 568 Where direct reduction steel-making is being practiced, small steel mills compete effectively with large mills using conventional practices.11 Thus, an important impact of a transition to direct reduc- tion in steel-making would be the increased viability of so-called mini- mills. Even without direct reduction, mini-mills are already beginning to spread the production of steel around the country and to lessen the former geographical concentration.1'11 Most mini-mills are said to be locating near the coastlines to facilitate both the import of foreign ore concentrates and water shipment of finished products.1 This dispersal trend could have profound social implications because over 600,000 work- ers are directly engaged in the basic steel industry and most are con- centrated in three states--Pennsylvania, Ohio, and Indiana. Over the long term, as nuclear powered/direct reduction steel-making becomes in- creasingly viable, a significant fraction of the steel industry may re- locate as it optimizes a new set of parameters in which the location of available metallurgical coal is much less important than previously. 4. Steel Summary Although the U.S. steel industry is likely to embrace nuclear powered/direct reduction steel-making less quickly than other countries because of the favorable U.S. resource position, a transition would have important environmental benefits (Table 17-4). Especially important would be the reduction in air pollution. Potentially profound social consequences would appear as relaxed locational constraints resulting in a new geographical distribution of the steel industry. C. Ammonia Synthesis Ammonia synthesis is the largest single useof hydrogen today. As discussed in Chapter 7, this hydrogen is obtained from the chemical re- forming of methane. Although methane is becoming increasingly scarce 371 PAGENO="0575" Table 17-4 SUMIvIARY OF IMPACTS OF NUCLEAR/DIRECT REDUCTION/ELECTRIC FURNACE STEEL-MAKING Magnitude of Impact Impact Class Stakeholder Nature of Effect (units) Environment Air pollution Steel industry Reduced air pollution from coke- Major (people, $) EPA making Public Mining Steel industry Reduced mining for coal (but demand Minor ($, people) Coal industry slack taken up by others energy Limestone industry needs) Public Reduced mining for limestone Moderate ($, people) Solid waste Steel industry Increased tailings from increased Moderate (people, $) EPA concentration of ore Public Decreased slag production Minor ($) Resources Public Improved utilization of natural Moderate ($) Safety Public Increased use of nuclear power, Major (people) especially with weapons-grade fuel Social Industry location Steel industry Dispersal of steel-making from pres- Major ($, people) Labor ent geographical concentration Resource extraction Coal industry Reduced need for metallurgical grade Minor ($, people) Labor coal (but slack taken up by other energy demands) Economic Capital investment Steel industry Potentially reduced investment per Minor ($) Capital market unit output Stockholders Production costs/market price Steel, industry Potentially reduced unit cost Minor ($) Consumers PAGENO="0576" 570 and expensive (when not subject to federal price regulations), the pri- ority held by ammonia producers to stores of natural gas is second only to the priority of residential use (Appendix A, Chapter 16) *12 ,13 This priority is a direct result of about three-fourths of all ammonia is being used as an agricultural fertilizer. Ammonia synthesis is a relatively simple and extremely well devel- oped chemical engineering process. Modern plants use their methane feedstock very efficiently to obtain hydrogen as a fuel and, indirectly, to separate nitrogen from the air (Chapter 7). If ammonia producers were unable to obtain their hydrogen from methane they could obtain it from other hydrocarbon sources more cheaply than from electrolytic hydrogen. Although the average interstate (regulated) price of natural gas was about $O.22/10~ SCF (standard cubic foot) in early 1974, some recent prices of unregulated intrastate gas have reached $2.OO/lO~ SCF in recent months (mid l975).14 It is reasonable to expect that unregu- lated intrastate natural gas prices to level off at about $2.5O/lO~ SCF before 1980.16 Table 17-5 compares the cost of alternative feedstocks that yield hydrogen at the same cost to an ammonia producer. It can be seem from Table 17-5 that electrolysis of water using electricity at $0.01 per kWh (a realistic cost) could not produce hydrogen competitively with reforming of either natural gas or other hydrocarbons until those fos- sil fuels had risen in cost dramatically. Moreover, it must be recalled that a rise in cost of those fuels would, in turn, cause the cost of electricity to rise by virtue of competition between energy forms and the need to use primary energy to generate electricity. It is apparent, therefore, that a considerable rearrangement would have to occur in both allocation priorities for natural gas and the rel- ative prices of various energy forms before hydrogen from coal or 373 PAGENO="0577" 571 electrolysis could be expected to become attractive to ammonia producers. Moreover, as other lower priority users of natural gas are curtailed, the lifetime of the supplies will be extended, which will increase the likelihood that ammonia producers will continue to receive methane on a priority basis. Table 17-5 ESTIMATED FEEDSTOCK PRICES THAT WOULD PRODUCE HYDROGEN AT EQUAL COSTS (ABOUT $l.5O/lO~ SCF) BY VARIOUS PROCESSES Process Steam reforming of methane* Electrolysis of water Alternative Hydrocarbons Steam reforming of naphtha Partial oxidation of naphtha Partial oxidation of residual oil Gasification of bituminous coal Approximate Feedstock Price (conventional unit) $ 4.70/103 SCF $ 0.010/kWh $ 0.50/gal $ 0.40/gal $17.00/barrel $46.00/ton Energy Unit (per 106 Btu) $4.95 $2.93 $4.17 $3.16 $2.70 $2.78 *At this high price for methane feedstock all other contributions to the cost of steam-reformed hydrogen are insignificant. 16 Source: Stanford Research Institute. If access to methane were to change, however, the building block description of Table 12-1 shows that a single nuclear-electrolytic plant could supply almost exactly two ammonia synthesis building blocks. How- ever, since even this demand falls short (only about one third) of the capacity of a 24-inch diameter hydrogen pipeline building block, the 374 62-332 0 - 76 - 37 PAGENO="0578" 572 hydrogen production would probably have to be quite close to the ammonia plant and employ a suboptimum delivery pipeline. Consequently, analysis of the relevant building blocks suggests that ammonia synthesis would either have to rely on electrolytic hydrogen production facilities dedi- cated to such synthesis or to wait until other large hydrogen demands had already justified deployment of large delivery pipelines* By far the more important consequence of ammonia producers joining in the hydrogen economy would arise from their changed criteria for plant location. Once access to abundant and low cost natural gas ceased to be the key variable, the plants would be free to locate close to their demand because the key plant feedstocks (water and nitrogen from the air) are widely available. Today most ammonia is shipped to market by combinations of barge, rail, and truck. However, several fairly large capacity ammonia pipelines are being built to connect producing regions to midwestern farming regions. Consequently, access to these pipelines might continue to constrain plant locations, even though, in principle, the plants could locate anywhere adequate supplies of pri- mary energy and water could be obtained. However, to the extent that this product pipeline constraint was not honored, the ammonia synthesis plants would almost surely locate in the farm regions--especially in the midwest--to be near the market. This implies a dispersal of the industry and an effect on the workers employed in production and transportation. *The reasons discussed here are the underlying justification for showing a late ammonia synthesis transition in the realistic implementation scenario depicted in Figure 13-2. 375 PAGENO="0579" 573 REFERENCES 1. R. J. Leary and G. M. Larwood, "Effects of Direct Reduction Upon Mineral Supply Requirements for Iron and Steel Production," Bureau of Mines Information Circular 8583 (1973). 2. N. Valery, "Steelmaking with Heat from the Atom," New Scientist (13 September 1973), pp. 610-615. 3. "The New Economics of World Steelmaking," Business Week (3 August 1974), pp. 34-39. 4. Statistical Abstract of the United States, 1974 (Bureau of the Cen- sus, U.S. Department of Commerce, July 1974). 5. "A Search for Clean Coking Processes," Steel Facts, No. 1, American Iron and Steel Institute, Washington, D.C. (1974). 6. D. J. Blickwede and T. F. Barnhardt, "The Use of Nuclear Energy in Steelmaking," presented at the First National Topical Meeting on Nuclear Process Heat Applications, Los Alamos Scientific Laboratory, Los Alamos, New Mexico, 1-3 October 1974. 7. E. Fein, "A Hydrogen Based Energy Economy," The Futures Group, Glastonbury, Connecticut (October 1972). 8. "Nuclear Reactors for Steelmaking," Business Week (19 October 1974), p. 52P. 9. M. Willrich and T. B. Taylor, Nuclear Theft, Risks and Safeguards (Ballinger Publishing Company, Cambridge, Massachusetts, 1974), p. 43. 10. "Coke Oven Control Program Could Cost Bethlehem Steel $40 Million," Air/Water Pollution Report (28 October 1974), p. 428. 11. "Hydrogen: Likely Fuel of the Future," Chemical and Engineering News (26 June 1972), pp. 14-17; "Hydrogen Fuel Use Calls for New Source," Chemical and Engineering News (3 July 1974), pp. 16-18; "Hydrogen Fuel Economy: Wide Ranging Changes," Chemical and Engi- neering News (10 July 1972), pp. 27-29. 376 PAGENO="0580" 574 12. "Natural Gas Users Sing a Dirge," Business Week (13 January 1975), pp. 37-40. 13. "Pushing for Priority," Chemical Week (3 April 1974), p. 15. 14. "A Furious Push to Deregulate Gas," Business Week (19 May 1975), pp. 91-92. 15. Mr. Robert Muller, Process Evaluation Department, Stanford Research Institute, Menlo Park, California (personal communication). 16. "Hydrogen and Other Synthetic Fuels," a summary of the work of the Synthetic Fuels Panel, prepared for the Federal Council on Science and Technology R&D Goals Study (September 1972) 377 PAGENO="0581" 575 GLOSSARY AIF Atomic Industrial Forum AISI American Iron and Steel Institute CAB Civil Aeronautics Board DoD Department of Defense DoT Department of Transportation EPA Environmental Protection Agency ERDA Energy Research and Development FAA Federal Aviation Agency FAR Federal Aviation Regulations FPC Federal Power Commission HTGR High Temperature Gas-cooled Reactor (Nuclear) IRS Internal Revenue Service 1~11~ Liquid Hydrogen LNG Liquid Natural Gas NASA National Aeronautics and Space Administration NEF Noise Exposure Forecast NSF National Science Foundation NTSB National Transportation Safety Board OPEC Organization of Petroleum Exporting Countries RANN Research Applied to National Needs, a Program of the National Science Foundation SCF Standard Cubic Foot SF0 San.Francisco International Airport SMSA Standard Metropolitan Statistical Area SNG Substitute Natural Gas SST Supersonic Transport 378 PAGENO="0582" 576 SONE THOtJGHTS ON THE AQUARIUS PROGRAM: A PROSPECTIVE WORLD EFFORT IN HYDROGEN-ENERGY by William J.D. Escher Escher Technology Associates St. Johns, Michigan Gist of this Paper Increasing discussion of what actions the U.S. and the World community, generally, can take in the sphere of energy is being heard. The tempo of the debate is accelerating; mention of "crash program' possiblilities is even heard occasionally. Consequently, n~ may be the time to bring forward focused energy program ideas, especially those which make long- term sense in view of the exhaustion of our fossil fuel reserves and energy-related environmental degradation we are experiencing. One such idea is that of a universal "hydrogen energy system' about which much has been spoken and written, but little yet accomplished in the sense or serious planning, much less physical research and development in imple- mentation of a planned hydrogen energy system. The United States is well known for its ability to establish an effective large-scale program involving technological developments, once the stage of "determination" has been reached on the national scale -~ usually late-in- the-day in the sense of our facing up to the basic challenge. This paper sketches out a "programatization" of the hydrogen energy system concept somewhat in the spirit of the Apollo space program, with which there are believed to be some obvious parallels. But AQUARIUS would be even a much more ambitious and longer termed program. It would involve practically all U.S. citizens and, hopefully, gain international participation. It could thus be a genuine World program, potentially. Expensive? Certainly. But the monies to be spent in research, development, demonstration and production PAGENO="0583" 577 and emplacement of the components of such a universal hydrogen energy system would be spent with the identical constituency who would profit in innumerable ways from the transition to hydrogen energy. OVERVIEW: PERSONIFICATION OF AQUARIUS Aquarius, the noted, astronomical and astrological water bearer, may be taking on new and important responsibilities in the critical energy field if heed is given to the promising, emerging concept of hydrogen- energy. If given adequate support, AQUARIUS-- a prospective World pro- gram effort in his namesake -- will bring clean, abundant energy to the peoples of the World who are so critically dependent on this resource. Abundant, clean energy irt the form of water. Water which has been energized with new non-fossil sources of energy. Clean because the combustion products of this `higher energy form of water" will be water itself in pure form. Abundant because the oceans of the World can be tapped in their virtually limitless supply of the single material feedstock required: water. And this water will be naturally recycled back to the oceans fol- lowing the energization, delivery and use cycle implicit in the system. Also, the primary energy sources to be utilized will be replenishable ones, or otherwise far more long-lived than our present fossil fuel energy supplies. For AQUARIUS will, in the long run, employ nuclear, geothermal and solar energy; the latter in many of its available form: direct thermal, ocean thermal, photovoltaic and wind. What will AQUARIUS deliver in fulfilling the promise of abundant clean energy? What is this "higher energy form of water'S? Merely the very elements of which water is composed: hydrogen and oxygen. Hydrogen is a uniquely advantageous fuel, much analagous to natural gas'. As a cryogenic liquid it can replace petroleum based fuels such as jet-fuel for aircraft. It can be delivered to the consumer in pipelines, rail tank cars and trucks, just as it is in very limited quantities today. Oxygen, presently a wide- spread and vital industrial chemical might find greatly expanded use if abundantly available at low cost, an expectation in view of its byproduct nature in hydrogen production from water. PAGENO="0584" 578 Once used by the energy consumer for any number of utilitarian purposes, from heating bathwater to flying an advanced supersonic airliner, the `higher energy form of water" reverts uniquely to its original form: H20, ordinary pure water. Such "water exhaust", if collected directly, can be used in manifold ways including drinking. Otherwise, it will disappear into the atmosphere as vapor. Either way, it will soon be returned to the oceans via natural processes. And the full cycle will nowhere despoil the environment. Thus, AQUARIUS is envisioned very much in the image of its mythological name~ake: a water bearer for the World who also will bring abundant clean energy as well. THE AQUARIUS PROGRAM As a program concept, AQUARIUS is a long-range, large-scale effort to effect a progressive conversion of our energy system over to that of hydrogen energy. Hydrogen energy is a broad term meant to include hydrogen itself as a new fuel, industrial feedstock, process conditioning medium, etc. It also covers the hydrogen_plus_oxygen bireactant combination to be employed where advantageous for zero-pollution and high energy conversion efficiencies, as in electrical fuel cell generators. Further, the direct use of oxygen produced in the water-splitting process yielding hydrogen is embraced under the term, hydrogen energy. The basic elements of a hydrogen energy system envisioned under the program concept are simply these: of hydrogen energy of hydrogen energy ~I1t~Jization of hydrogen energy The timing of the program, briefly, is; first, near-term feasibility and demonstration, supported by longer-ranged research and development; secondly, progressive conversion to the ultimate hydrogen energy based system. PAGENO="0585" 579 The technical approach for AQUARIUS, as a dedicated and subscribed-to national (or international) program would focus on the establishment of a total hydrogen production, delivery and utilization system to serve our citizens. Implementation details for this have already been established by researchers in the hydrogen energy field. This work includes technology impact assessments of hydrogen energy as a step toward assuring that un- desirable consequences of a conversion to this system are absolutely min- imized. The fact that hydrogen energy can, in fact, along with electricity, serve virtually all energy needs has been firmly established. Many such uses have been physically demonatrated: automobiles, aircraft, appliances, elec- trical generation, etc. Although the major technical alternatives for constructing the system have been debated, an agreed upon "blueprint" of the system is not yet in hand. Work has just been initiated ~t the Federal Government level to this end. For illustration purposes, one nominal approach for implemention would provide the following elements: (1) Ocean based (offshore to open-ocean) production of hydrogen and oxygen using nuclear and/or solar primary energy sources, with the products converted to cryogenic liquid form (2) Transportation to U.S. (and global) ports of the cryogenic hydrogen energy by Cryosupertankers (3) Storage near the ports with subsequent land transportation via pipelines end rail/highway transporters to using centers (4) Broad utilization of the 1~ydrogen energy in industrial, electrical utility, conunercial and residential, and transportation sectors As a fully developed system supplying the bulk of our energy needs, the above described system represents an ultimate stage of development, one not available perhaps until well beyond the year 2000. This is the case even if work began iunnediately, because of the long lead-times involved and the enormous investhents required. Evolutionary change is clearly the path we will be following into a "hydrogen economy". PAGENO="0586" 580 Nevertheless, if we wish to evolve into a hydrogen energy system in a timely manner, noting our critical energy/environmental status, we must make a vigorous start in this direction. In the near term the AQUARIUS Program would proceed into a widespread demonstration phase, where existing technologies would be employed and our present, though limited production, delivery and utilization facilities put into maximum play. Education and familiarization oriented efforts would be started. Experimental prototype hardware would be built and operated to gain ex- perience and technical data to guide planning. The above-listed exemplary technical approach~, if pursued, implies the need for intensive research and developmeni activities leading to feasible and economic means of ,implementing the following system elements: Ocean-based cryogenic hydrogen-energy production facilities based on nuclear and solar energy conversion Cryosupertankers capable of ocean delivery of produced hydrogen and oxygen, including docking/loading provisions at both route-ends Pipeline transmission systems and vehicular delivery means for economical delivery of hydrogen and oxygen over long distances, including large bulk storage components City gate/load center processing and distribution means for moving hydrogen energy to the ultimate consumers Utilization sector equipment compatthle with hydrogen energy: Industrial sector -- Feedstock, processing medium and chemical uses; use for process steam and heat production Electrical utility sector -- Electricity generation at load center in zero emission, quiet high-response facil- ities (e.g. fuel cells); special load-leveling means Commercial and Residential sector -- Space heating and cooling, water heating, cooking; commodity distribution Transportation sector -- Aircraft (subsonic and supersonic transports), ships and surface-effect/hydrofoil vehicles, trains and guideway-supported high speed transportation systems, trucks and buses, automobiles PAGENO="0587" 581 Again, it can be noted that some degree of serious study has been given to each of the `above .areas by researchers In hydrogen energy In the U. S. and abroad. Recently, a U.S./Japan seminar was convened under joint government auspices, to share technical views and information on the "key technologies" of the hydrogen energy system concept. In many instances preliminary experimentation and hardware demonstration has been successfully carried out, often with. totally inadequate financial support. For instance, some 15 hydrogen-fueled internal combustion engine projects oriented to automotive use, have been carried out in the past several years in the U.S. (A survey report describing this work is being published by the Energy Research and Development Administration presently.) Though Impressive technical accomplishments were made, understandably the results are limited and non-focused at this tine; an "optimum" hydrogen engine remains undefined. Inter- est and experimental activities on hydrogen-energy based automotive systems have been noted in Europe and Japan as well. Based on most promising technical results in adopting liquid hydrogen fuel for aircraft as revealed by industry and government investigations to date, the aviation community is `addressing a proposed early-demonstration in flight of what may well be its "fuel of the future." Significant funding will be required for such a demonstration. Much more will be required for the develop- ment of.. an aircraft specifically designed for hydrogen, one which promises to be technically and economically superior to today's PAGENO="0588" 582 hydrocarbon fueled aircraft. AQUARIUS would necessarily vastly expand such efforts in the future, proceeding from today's baseline-status as evidenced by the kinds of projects illustrated above. But it would do so in the context of a unified, conprehensive program plan. This is what is lacking to date, and understandably so without a major commitnent to the hydrogen-energy system evolution we are addressing. Presently, under the auspices of the National Aeronautics and Space Administration, workers at the Jet Propulsion Laboratory and the various NASA field centers are developing what in essence is a national preliminary progran plan for a hydrogen energy system. Comprehensive reference has been made to all known previous and presently pursued work in this field as background in this effort. This just might constitute a rational beginning for such an anbitious program as AQUARIUS. PAGENO="0589" 583 UNION CARBIDE CORPORATION 270 PARK AVENUE, NEW YORK, N. Y. 10017 September 3, 1975 Mr. Mike McCormack, Chairman Subcommittee on Energy Research, Development and Demonstration Committee on Science and Technology U.S. House of Representatives Suite 2321 Rayburn House Office Building Washington, D.C. 20515 Re: Subcommittee on Energy Research Development and Demonstration Hearings on Hydrogen Energy Dear Mr. McCormack: Thank you for the opportunity to provide an additional statement for the hydrogen energy hearing record. Our position on the possibilities for hydrogen energy development was kindly included by Mr. Derek Gregory as an attachment to his prepared testimony submitted June 12 (ref. -Pipeline Hydrogen, the fuel for the Nuclear Age, pp. 18-25, "The Status of Hydrogen Technology Application"). I have reviewed that paper which is now nine months' old, and find it generally consistent with my current thinking. I also found the testimony submitted at the hearings to consist of competent and fairly thorough presentation of the problems and opportunities for hydrogen energy development. To briefly summarize my opinion on the current status of hydrogen energy development, I feel that there is no longer any question on the long range importance of hydrogen energy systems development but that the question is on the magnitude of the commitment that should be made now toward developing these potentialities. Although research in all aspects of production/distribution/util- izat ion would benefit the long term potential for hydrogen energy system development, the timeliness of these efforts can be PAGENO="0590" 584 Mr. Mike McCormack -2- September 3, 1975 improved by emphasizing near term demonstration in applications where the benefits of hydrogen energy would most likely be greatest. My opinion is that aviation and electrical energy distribution applications would benefit the most. Existing hydrogen production and distribution technology, although improveable, is adequate to supply these demonstration applications which are required to prove the benefits of hydrogen fuel and to motivate customer acceptance of a new energy source. Demonstration projects will further provide a basis on which to nucleate and apply the additional benefits of Energy R/D which no doubt would more easily flow from more visible application opportunities. I appreciate the opportunity you have afforded me to contribute to these important considerations. If there are any questions or further information required, please do not hesitate to call. Sincerely, John E. Johnson Assoc. Manager Feedstock and Energy Policy Office Union Carbide Corporation JEJ: si PAGENO="0591" 585 ELECTRIC POWER RESEARCH INSTITUTE EPRI August 29, 1975 The Hon. Mike McCormack, Chairman Subcommittee on Energy Research Committee on Science and Technology U.S. House of Representatives Washington, D.C. 20515 Dear Mr. McCormack: Dr. Robert Loftness from EPRI's Washington Office has transmitted your invitation to contribute for the record a written statement on relevant aspects of hydrogen energy. Because EPRI's efforts in this topical area are in a relatively early stage, we feel that it is somewhat too early for us to go on record. We will be happy to do so when sev- eral key studies will be completed approximately a year from now. In the meantime, and in the hope that this will be of some help to you and your subcommittee, I offer the following comments: - It appears certain that hydrogen will play an important role as a versatile energy carrier in the future energy systems of the United States and other industrialized countries. - The current (primarily, chemical and industrial) uses of hydrogen can be expected to increase steadily, but technical, economic and institutional factors are likely to combine in delaying a significant expansion of hydro- gen to other uses. Over the near and intermediate term, the most important of these factors are (1) uncertain cost-competitiveness and probable logistic debits of coal-derived hydrogen compared to liquid and gaseous (petroleum and synthetic) fuels, (2) lack of highly efficient, low cost methods for production of hydrogen from water and energy, and (3) limited availability of primary, non-fossil energy sources for hydrogen production. - A certain expansion of hydrogen's role over the coming 10-20 years can be expected. One possible application would be production of hydrogen with the electric utili- ties' off-peak power. It appears that multiple uses -- Headquarters: 3412 Hillview Avenue, Post Office Box 10412, Palo Alto, CA 94303 (415) 493-4800 Washington Office. 1750 New York Avenue, NW, Suite 835, Washington, DC 20006 (202) 872-9222 PAGENO="0592" 586 The Hon. Mike McCormack August 29, 1975 Page 2 including sale as chemical, and reconversion to peaking power -- will be required to economically justify the production of this off-peak hydrogen. Considerable more analysis of this and other specific hydrogen energy systems will be needed to identify logical uses and appropriate development efforts. - Availability of efficient, low-cost methods for production and storage of hydrogen will be a prerequisite for any future, broad-based hydrogen energy system. Because of the extensive development efforts and time required, the necessary R & D should be identified and initiated as soon as possible. This should include development of (1) ad- vanced water electrolysis technology, (2) processes for thermochemical splitting of water, (3) hydrogen storage methods, and (4) devices (such as fuel cells) for the efficient conversion of hydrogen to electric and thermal energy. - EPRI expects to actively participate in hydrogen-related R & D with potential for benefits to the electric utilities and the customers served by them. However, because of the breadth of potential uses and the multiplicity of hydrogen production, conversion, storage and utilization technologies, the Federal Government will have to play a major role in hydrogen energy research, development and dernnnstration. Very truly yours, Fritz R. Kalhamrner, Manager Electrochemical Energy Conversion and Storage FRIK/sl cc: R. E. Balzhiser R. Loftness PAGENO="0593" 587 * WRITTEN STATEMENT OF Dr. Ran Manvi, P. E. Mechanical Engineering Department California State University, Los Angeles on HYDROGEN ENERGY APPLICATIONS for the Subcommittee on Energy Research, Development, and Demonstration Committee on Science and Technology House of Representatives Mr. Chairman and Members of the Committee: I appreciate this opportunity to provide you with a written statement concerning the utilization and production of hydrogen. I teach, conduct research, and perform consulting services in several area~of the thermal engineering field. Since this field will be directly affected by development of hydrogen-energy technology, I have studied to some depth the possible role of hydrogen in our Nation's future energy systems. My own personal thoughts are discussed in the following paragraphs. Summary I feel that widespread use of hydrogen as a universal fuel will not be realized during this century. Hydrogen is, however, capable of serving as an important tool, permitting a variety of strategies to be considered for the solution of our energy problems. There is already a significant current usage of hydrogen, dominated by chemical uses in ammonia production and petroleum refining operations. I believe that the growth of hydrogen demand for chemical needs is certain. New applications, such as coal gasification and liquefaction and as a direct special-purpose fuel, are expected to appear and the magnitude of such demand depends on the energy scenario for the country. In order to assure a stable hydrogen supply in the future for the essential ammonia ferti- lizera sad other important chemicals, we have to discontinue the current practice 62-332 0 - 76 - 38 PAGENO="0594" 588 of producing hydrogen from rapidly depleting fossil sources such as natural gas as soon as possible and shift to alternative methods. I urge the policymakers to take immediate action along the lines suggested in the text of this paper. What is Hydrogen's Role in the Energy Field? During the last five years, several good system studies have discussed "Hydrogen Economy" and "Eco-Energy" as being means of providing answers to a wide range of energy problems in the United States. The concepts, as presented in these recent studies and many other publications, consider hydrogen to be a universal fuel, storage medium, and transport medium. Ny concept of the role of hydrogen in the Nation's energy system is more limited and does not go as far as that identified in these studies and other large number of publications. I feel that the use of hydrogen in the energy system of the country will develop in an evolutionary manner and that it is not likely that it will become so all-pervasive as is conceived by some strong "hydrogen advocates". Based on our present understanding, it is certain that traditional uses of hydrogen as an industrial chemical would keep on growing at the rate of 6% to 7%. Also, it would appear that hydrogen can play a valuable role as a fuel; Under certain circumstances, as a storage medium to enhance the application of some energy systems; and as a transmission medium in a limited number of applIcations. The degree to which hydrogen is used in these roles is strongly dependent on one's presumed energy scenario for the country. It is felt likely that, barring unforeseen developments, the energy scenario for the country will provide a broad spectrum of energy sources, means of storage, means of transmission, and means of providing energy for transportation requirements. This spectrum of alternatives will provide protection against unforeseen consequences of considering only one alternative and will provide the versatility required to permit regional solutions to develop. Under these circumstances, hydrogen, while being an important part of the overall energy system, will not play as all-pervasive a role as suggested by some authors. What Are the Major Factors Governing Hydrogen's Role? Hydrogen energy systems can potentially be implemented in four large-scale application areas. These potential applications, along with illustrative examples, are: 2 PAGENO="0595" 589 1. Energy transmission: gaseous-hydrogen pipeline transmission of large blocks of energy similar to the existing natural gas network. 2. Energy storage: electric-utility generation of hydrogen (via electroly- sis) during off-peak periods, storage in, e.g., hydride form for compactness, and reconversion to electricity (via fuel cells) during peak demand periods. 3. Residential and commercial needs: employ efficient and non-polluting catalytic hydrogen combustion in ventless appliances for space heating, *water heating, and air conditioning of commercial and residential buildings. 4. Transportation: vehicular propulsion with low-polluting hydrogen, particularly airborne vehicles where the high energy content per unit weight of hydrogen provides a significant performance advantage. At present, hydrogen's role is almost entirely that of a unique industrial chemical where there are essentially no alternatives to hydrogen usage. All the new potential large-scale uses mentioned above are now and can be fulfilled by alternatives to hydrogen, particularly during the balance of this century. Thus, the viability of these possible new roles for hydrogen and the rate and time of implementation depend on how hydrogen compares with its alternatives. I believe that the lowest cost or most economically viable option over the projected life of the system will most likely be implemented. Under the proviso that each option must be socially and environmentally acceptable, each option incorporates features such as air pollution control equipment, and these factors are thereby reflected in costs. In this context, cost aspects will play a dominant role in selecting a system. This selection basis favors existing and established systems as long as they are viable in terms of fuel resources. Use of such established systems derives maximum benefits from existing large capital investments and minimizes risks via use of well-developed, proven technology. Large-scale displacement of still- viable traditional systems by hydrogen energy systems will require the availability of hydrogen at sufficiently low costs (advanced production methods) to provide an 3 PAGENO="0596" 590 overall economic advantage. Such low-cost production methods are unlikely to be available in this century, and are likely to be available in the next century only if a considerable Federal research and development effort is undertaken immediately. Existing systems will continue to dominate until petroleum and natural gas become sufficiently scarce and costly to warrant a change. Coal is in relatively abundant supply and appears to be the next logical fuel resource to exploit. Coal usage is particularly enhanced by recent studies which indicate that both natural gas and petroleum-derived fuels can be replaced essentially on a one-for-one basis by coal-derived fuels, i.e., substitute natural gas (SNG) in place of natural gas and syncrude in place of crude oil. The cost of these synthetic fuels from coal is estimated to be viable, e.g., syncrude is now projected to be competitive with present high-cost, imported crude oil. The one- for-one replacement of present fossil fuels has large economic leverage in using existing systems. For example, SNG can be delivered and used in the present natural gas system; present transportation systems such as authomobiles, ships, - and airplanes can use synthetic gasoline without significantly modifying vehicles or fuel supply networks. Since coal is estimated to be in good supply at least up through the year 2050, it is unlikely that large-scale shifts to hydrogen energy systems will occur before the year 2000. In the 25-year period up to the year 2000, hydrogen's end-use role appears to be (1) continued growth in the unique chemical sector, (2) relatively small but important special-purpose applications which exploit hydrogen's low pollution characteristics, and (3) military uses to gain either performance advantages or logistic benefits in terms of fuel supply. Hydrogen is particularly suited for fuel cells and some uses such as electric- utility peaking are possible, but these involve relatively small percentages of the nationwide energy supply system. - As the fossil age draws to a close, society will have to make widespread use of synthetic energy forms to meet its varied energy needs. Electricity, one such form, is already playing an important role and increasing in its importance. Hydrogen appears to be the best bet among all the synthetic fuels under consider- ation to meet our ultimate energy needs. In addition, hydrogen has and will have 4 PAGENO="0597" 591 important value for non-fuel uses, especially as a chemical feedstock. In the period sometime in the future when fossil fuels including coal become scarce, costly, and environmentally or socially unattractive, hydrogen appears to be a viable candidate for wide-scale implementation in at least some of the four major areas cited earlier. How Does Hydrogen's Role Affect Primary Energy Resources? Hydrogen does not add to the Nation's primary energy resources since, like electricity, it has to be obtained from some such source. However, it has minimal pollution, can replace nearly all presently used fuels, and can be derived from water using such primary energy sources as nuclear, solar, wind, and geothermal. Our Nation's future energy system, definitely, is not one in which hydrogen replaces fossil fuels and presently-used means for storage and transmission of energy and becomes a "universal' energy storage, transmission, and combustion medium. It does, however, involve the potential wide-scale use of hydrogen for these applications. I envisage an orderly growth with hydrogen being used in industrial applications such as making fertilizers, later adopted in specialized transportation applications being incorporated in industrial processes where the chemical hydrogen is required; becoming used as an energy storage medium primarily for energy sources which have large diurnal variations such as solar energy and wind energy; and, finally, being used as a distribution ~medium if the energy scenarios which develop in the country include a requirement for the very long distance transmission of portable fuels from source to point of consumption. I wish to emphasize that the application of hydrogen in the economic system of the country is very dependent on the set of energy strategies which are ultimately adopted. These energy strategies, in turn, largely revolve around depletion of fossil primary energy resources and the resulting need to shift to other renewable sources. The type of hydrogen production process and its associated cost and efficiency depend on the energy source. Thus, the extent of hydrogen use will be affected by the relative use of different primary energy sources as determined by the adoption of specific strategies. Further, considera- tion of expanded roles for hydrogen may make the adoption of some of these 5 PAGENO="0598" 592 strategies more feasible and thereby influence the selection of a strategy. I feel the selected strategy for solving the country's energy problems should involve a multiplicity of energy systems. Therefore, viewed in this context, hydrogen becomes an inportant tool, permitting a greater variety of strategies to be considered and ultimately the selection of a more viable and flexible strategy.. How Should Hydrogen's Role Be Implemented? The need for action by policymakers is obvious. I don't think we need very many more general studies because we aren't going to be able to pick and choose between the various suggested solutions to an energy problem that have merit based on studies to date. We have to pursue them all to the best of our ability. Then, when more data have been acquired, meaningful selections can be made. We urgently need to avoid falling into the trap of "paralysis by analysis". This is especially true in the case of hydrogen for which we often ignore the fact that there exists a large base of knowledge and experience with respect to its production, handling, and use by chemical industries and by NASA for the space effort. Our problem, then, is to bring hydrogen energy systems to the point where they provide viable options as the economic climate permits, rather than to force an unreasonable solution before it fits economically. The danger is that premature decisions based on hasty assessments would delay development of hydrogen energy systems until the hydrocarbon price is so high that hydrogen is then an attractive alternative and ~ then initiate the necessary research and development which might require significant additional time. My use of the term economic is meant to include technological, environmental, political, and social factors that play such a significant and inseparable role in the real cost of all the energy systems. So far, hydrogen energy system studies have been conducted or sponsored independently by Federal agencies such as AEC (now part of ERDA), NASA, NBS, DOD, DOT, NSF, and EPA. These studies have discussed the. need for research and development work having identified the attractiveness of hydrogen for various end uses. On the other hand, electric and gas utilities sponsored their own studies at G.E. TEMPO, General Atomic, and IGT to identify future potential and 6 PAGENO="0599" 593 establish their interests. There has been very little coordination among these studies, and quite often there is too much of a tendency to rest the technology requirement justification solely on the need to meet projected increased utilization. It should be recognized that, if a planned large-scale hydrogen energy system is to materialize, it may well be initiated in the industrial chemical sector. Even if the projected increased utilization fails to come about, there will always remain the need of meeting the hydrogen demand as a unique chemical. At the present time, approximately 3 trillion SCF of hydrogen with a market value of 1.5 billion dollars is consumed annually, mostly in the chemical industry. Historically, the growth of the chemical industry in this country has been at a rate approximately twice the GNP growth. In order to sustain a 3% to 4% GNP growth, chemical industry growth rates of 6% to 8% are not unreasonable. With a hydrogen-use growth rate at 7%, the chemical demand alone would be approximately 16 trillion SCF by year 2000. Cumulatively, we are likely to produce and consume nearly 250 trillion SCF of hydrogen between now and the year 2000. If natural gas and oil are used as sources of hydrogen, as is the current practice, then we would require about ~-7O x 1015 BTU of these sources for hydrogen production at an efficiency of ~-6O% (typical for steam reforming and partial oxidation plants). This, indeed, would pose serious problems because discovered recoverable (inferred) U.S. natural gas and petroleum resources as of 1974 are only 250 x 1015 BTU, and 270 x 1015 BTU, respectively. It is not surprising, therefore, that leaders in the chemical industry are worried about hydrogen feedstocks. Imagine what would happen in this country if we run short of ammonia for fertili- zers or methanol for plastics because hydrogen was hard to obtain! It is in the national interest to assure hydrogen availability. I suggest, therefore, the formulation of a national hydrogen supply plan for the future. The plan should aim at developing a stable hydrogen supply as follows: 1. All incremental additions to existing production facilities be barred from using natural gas as the feedstock. However, they should be allowed to use low-quality oil for immediate needs. 2. Discontinue, over a carefully scheduled and controlled time period, the current industrial practice of internal production of required hydrogen from natural gas and oil. PAGENO="0600" 594 3. Develop concepts and arrangements for producing and distributing industrial requirements of hydrogen at and from large facilites. These "hydrogen utilities" would produce the required hydrogen initially from solid wastes, coal, and, subsequently, from nuclear, solar, wind, and other primary energy sources. Since the chemical market is reason- ably assured and growing, such utilities would get quickly established. Techniques for hydrogen production from coal, even though not very efficient, compared to the potential of future advanced technology, are already available. Hydrogen from solid wastes is being studied by Linde (PUROX process) and probably would require some development. Hydrogen distribution for industrial uses has been carried out on a limited scale in Germany and Texas. However, in order to develop the concept of externally produced hydrogen, direct involvement of both industry and government is absolutely necessary. The sooner this involvement begins, the better. A Federal agency with strong experience in working with industry should be assigned the role of the coordinator to work and cooperate with industry. 4. Develop the concept of the "electric and hydrogen" energy system of the future. Both of these secondary energy forms are essential. It is con- ceivable that electricity would play a greater role after the year 2000. Attempting to determine the ultimate split between these two energy forms for meeting is premature and to some extent unnecessary since they can operate in a complementary manner similar to electric and natural gas systems of today. Both forms of energy need to be developed so that the optimum combination can be selected based on local or regional cir- cumstances. What Actions Are Required? It would seem that the most prudent set of actions would be to: 1. Identify a Federal agency to work with industry and assume the role of the coordinator for a national hydrogen plan as outlined earlier. 2. Keep the momentum going on hydrogen energy research by adequately supporting the following which are essential for the success of a national plan: 8 PAGENO="0601" 595 o Proof of concept for optimal solid-waste-to-hydrogen and coal-to- hydrogen processes. Demonstration of complete production and delivery systems, concurrent with fundamental experimental work to understand key parameters well enough to scale up the systems with minimal cost risk. o Basic and experimental research on electrolysis of water to achieve increased efficiency and high pressure delivery. o Set up a number of mini-pilot hydrogen production facilities from electrolysis to help gather the data for "scale-up" models. o Basic and experimental research on thermo-chemical water splitting to find more efficient cycles with less corrosive materials. o Concept studies on what to do with oxygen coproduced in some (large) hydrogen production facilities. o Concept studies, basic research, and mini-demonstration plants utilizing solar energy for hydrogen production to provide technical and economic data to determine relative roles of thermal electric photovoltaic, and photosynthetic energy conversion techniques. o Improved hydrogen liquefaction facilities. o Experimental research and demonstration of hydrogen underground storage to obtain engineering data on charging, storage, and dis- charging. o Improved hydrogen compressors, valves, and associated transmission equipment such as metering devices. o Materials research and development to demonstrate satisfactory materials availability for hydrogen pipelines, valves, compressors, regulators, and metering devices. o Laboratory demonstration of a number of devices and processes in which the use of hydrogen has the potential to provide unique benefits, i.e., pollution reduction, and better efficiency. These should be identified and necessary utilization technology developed. For example, hydrogen- oxygen turbines, industrial and commercial burners, etc. PAGENO="0602" 596 I shall be very happy, Mr. Chairman, to provide any additional information you need. I would like to end my written statement by reiterating the strong need for immediate action on the part of policymakers. Thank you. 10 PAGENO="0603" 597 OAK RIDGE NATIONAL LABORATORY OPERATEO BY UNION CARBIDE CORPORATION NUCLEAR DIVJSWN POST OFFICE BOX X OAK RIDGE, TENNESSEE 37830 September 9, 1975 Honorable Mike McCormack, Chairman Subcommittee on Energy Research, Development and Demonstration U. S. House of Representatives ~ Suite 2321, Rayburn House Office Building Washington, D.C. 20515 Dear Mr. McCormack: I am pleased to respond to your request of August 4, 1975, concerning my views on hydrogen. The attached comments largely represent a brief summary of an AEC (now ERDA) panel which spent about six months investigating the prospects of hydrogen and other synthetic fuels as a means of alleviating some of the nation's energy problems. During this investigative effort, expertise from all available sectors was sought in order to obtain a balanced view of this subject. Since this work was completed, some of the recommendations have been implemented in relatively small R&D programs, e.g.: - some work is in progress at Brookhaven National Lab in cooperation with the Public Service Elec.tric and Gas Co. of N.J. to develop a hydrogen system for meeting utility peak loads; - some work is in progress at several national laboratories on the thermochemical production of hydrogen; - as part of the coal conversion program, processes for producing hydrogen from coal are being developed. In general, however, relatively little effort is in progress, which is probably due to the relization that "The Hydrogen Economy" is a long- range concept. While this is undoubtably true, a danger exists wherein our concerns with near-term problems can prevent solutions to problems of a long-term nature. If I can be of any further assistance, please call on me. S ce~%~( John W. Michel `1 Technical Assistant for Advanced Energy Systems Attachment PAGENO="0604" 598 PREPARED TESTIMONY ON itYDROGEN FOR THE SUBCOMMITTEE ON EUEi~JY RESEARCH. DEVELOPMENT. AND DEMONSTRATION J. U. i~ichel Oak Ridge National Laboratory The U.S. Federal Government through a number of its agencies has been involved in various aspects of hydrogen for many years. Some of the significant efforts vere: U.S. Army/AEC - Energy Depot Study - early 1960's NASA/ARC - Space Applications - beginning early 1960's OST/AEC - Synthetic Fuels Study - l9~2 NASA - Hydrogen Energy Systems Technology Study - current Other aFencies which performed or sponsored related york include: Naval Reaearch Lob ERDA FPC DOD The most recent published, comprehensive evaluation of hydrogen as a aynthetic fuel is the OST/AEC work of 1972, "Hydrogen and Other Synthetic Fuels" *l Since most of the information and conclusions in this report are still valid and applicable, I would like to present a brief summary for your records. 1 Report No. TID-26l36, September, 1972. 9 / 75 PAGENO="0605" 5~4ą SUMMARY OF PANEL REPORT HYDROGEN AND OTHER SYNTHETIC FUELS* INTRODUCTION Early in 1972 the Energy R&D Goals Committee of the Federal Council on Science and Technology organized a study to assess a number of basic energy technologies which could favorably influence the U.S. future energy supplies. Various federal agencies sponsored eleven technical panels to perform this assessment and to prepare R&D plans for developing the priority technologies. The findings of one of these panels, "Hydrogen and Synthetic Fuels," sponsored by the USAEC, is summarized in this testimony. Whil.e there are currently serious problems in providing adequate electricity, the longer-term energy problems seem to be more associated with providing an assured supply of environmentally acceptable portable fuels. The importance of this supply is apparent when it is realized that electrical energy only meets about one-tenth of our end-energy needs today - the remainder is supplied from fossil fuels, mainly petroleum and natural gas. While production of synthetic fuels requires thermal or electrical energy and thus may appear to complicate an already difficult problem, this energy can be obtained from domestic and, for the most part, clean sources, e.g., nuclear or solar. Further, because of low transport costs, synthetic fuels can be produced at remote, well-regulated plants and thus would not contribute to the primary pollution problems that exist in our urban centers. An additional consequence of such a system is that of conservation of our limited fossil fuel resources, particularly petroleum, so that they may be used as valuable chemical product feedstocks and in metallurgical processes. The synthetic fuels, especially hydrogen, may be consumed with very little or no air pollution as well as with higher conversion efficiencies and thus could be more attractive for urban uses than the fossil fuels in current use. Hydrogen has long been recognizedl~2 as an attractive fuel, since it is clean burning, adaptable to a wide variety of uses, and is available from a renewable and universal raw material, water. Primarily because of its high relative cost, it is not, however, currently used as a common fuel but is used on a large scale as a chemical reactant, particularly in the manufacture of wsmonia and in petroleum refining operations. Some fifty years ago it was piped into many houses as `towngss", a coal derived gas mixture containing CD, for fuel and lighting uses. It is now made largely from fossil fuels, *Research sponsored by the U.S. Energy Research and Development Administration under contract with the Union Carbide Corporation. lj~ B. S. Haldane, "Daedalus, or Science and the Future", A Paper Read to the Heretics on February ~, 1923, Cambridge. 2R. A. Erren and V. H. Cmnpbell, "Hydrogen from Off-Peak Power -- A Possible Commercial Fuel", Chem. Trade J. 92, 238-39 (1933). PAGENO="0606" 600 predominantly natural gas and petroleum, but as these materials become more scarce, it could be produced on a large scale from coal or directly by water electrolysis. These processes, however, require considerable energy; for example, even with somewhat advanced water electrolysis technology, 3 to ~ Btu as heat are needed to produce the required electricity for one Btu of heat obtainable from the combustion of H2. Thus, an overall thermal efficiency of 25 to 33% is realized. The fossil based processes typically are 55 to 70% efficient. Thus, it is important to recognize that hydrogen is not a primary energy source and should be considered a means for transporting or storing energy. However, it should also be recognized that production of hydrogen may be the best mode of making use of several primary energy forms, for example, solar, wind, tides, and perhaps remote hydro or ocean-based plants. These energy forms are characterized by a cylic availability in which energy storage becomes important or by a remote location in which energy transport is a critical factor. Thus, hydrogen could play an essential role in making alternative primary energy resources available for our long-term fuel requirements, thereby conserving our limited fossil energy resources. It may also prove to be a good means for making full use of nuclear plants when the national power system eventually becomes predominantly nuclear. At this time, significant unused generating capacity, because of demand patterns, should be available for hydrogen production via water electrolysis under attractive economic conditions. In addition, it may be that converting coal or lignite to hydrogen will be one of the best means for utilizing our vast coal deposits. Often, the integrated production, transmission and end use of hydrogen, as illustrated in Fig. l,has been referred to as the `Hydrogen Economy". The panel report discussed the major aspects of this possible future system giving emphasis to the present and projected state of the technology and economics as well as to several important environmental and conservation factors. It is important at the outset to recognize that the hydrogen economy is not likely to be implemented in a significant manner for at least several decades. It is equally important to appreciate the long tine requirements historically achieved for introducing new fuel systems. Thus, performing the required R&D early to develop a technology readiness for such options would appear to be a prudent policy. The intent of this paper is to summarize the findings of the Synthetic Fuels Panel which evaluated the major aspects of new fuels systems, i.e., production, storage and transportation, end uses and an overall systems analysis. While the emphasis was on hydrogen and other fuels from nonfossil sources, a section on the use of coal to produce hydrogen and methanol was included to help define the interim time period before our dependence on non- onsil Lucks occurs. The organization of the panel and the main contributors to the effort are given in the Appendix. PAGENO="0607" C;-[~,7 73-4225 PRODUCTION TRANSMISSION/ STORAGE/DISTRIBUTION UTILIZATION NUCLEAR HYDROGEN PRODUCTION FACILITY ELECTRICAL rTa 11f PD ~T~O COMMERCIAL AND RESIDENTIAL p PPDPDPDIT TRANSPORTAT1ON INDUSTRIAL UNDERGROUND STORAGE Figure 1. The HydroFen Economy PAGENO="0608" 602 SU~2~ARY AND CONCLUSIONS The primary sectors of an energy system based on nonfossil syminetic fuels have been examined on the basis of readily available information. The cain overall conclusion reached is that these fuels can have a significant beneficial long-term impact on the energy problems facing the U.S. Hydrogen is a particularly attractive synthetic fuel for the following reasons: 1. It is essentially clean burning, the main combustion product being water. 2. It may be substituted for nearly all fuel uses. 3. It can be produced from domestic resources. 1~. It is available from a renewable and universal raw material--water. 5. Nearly all primary energy sources, nuclear, solar, etc., may be used in its production. The main obstacles to the use of hydrogen as a universal fuel are its high cost relative to the current low prices for fossil fuels and, for some applications, the unresolved problems of handling a low-density or a cryogenic fluid. Safety considerations, while important, are not believed to present a serious technical obstacle to its widespread use. The panel believes that most of these economic problems could be resolved by appropriate research and development programs and, even though some applica- tions are of a long-term nature, that it would be prudent to begin the required research at once. The solutions to research and development problems cannot often be rigorously scheduled, and, particularly in this case where a serious national problem exists, it would be far better to have technology ready in advance than to be late. Attaining the technical and economic goals of such a program could allow the U.S. to be independent of foreign energy sources while essentially eliminating the pollution problems related to energy use. Of the other synthetic fuels considered by the panel, methanol (providod a low-cost source of carbon ouch me coal or lignite is available) appeared to offer the most potential, particularly as a fuel for ground transport. A comparison of selected characterisitcs of the synthetic fuels considered in this study is given in Table 1. PAGENO="0609" 603 Major Findings The long-term need for synthetic gaseous and liquid fuels is believed to be incontrovertible when one considers the potential alternatives. Although the applications of electricity, the most likely alternative, are increasing, there are several energy use sectors which do not appear capable of adapting to this energy form, for example, transportation, particularly air and sea. Also, many chemical and metallurgical uses for hydrogen cannot be replaced directly by electricity. The need for a portable, storable, and readily deliver- able form of energy seems to be an essential ingredient of an advanced society as far into the future as can be visualized today, certainly beyond the time when the earth's fossil fuels have been exhausted. The panel concluded that hydrogen has outstanding potential as a fuel for the transportation sector because of its uniquo, rionpo]Jutirig character. The applications would initially be to fleet-operate6 trucks and buses, high-speed trains, and aircraft and may later extend to private automobiles. The key to realizing the potential of hydrogen as applied to the transportation sector is the development of practical on-board storage and logistics systems. Methanol was identified as an attractive near-term automotive fuel. While not as clean burning as hydrogen, it appears to be superior to gasoline and would more readily fit into existing vehicle designs and fuel logistics systems, although its relatively low heating value and boiling point imply changes in on-board storage concepts. The panel also found that conversion of agricultural and urban wastes to synthetic fuels is worthy of serious consideration. This source could supply a significant fraction of the 1985 shortage of pipeline gas, probably at costs competitive with imports. However, a substantial program of research, develop- ment, and demonstration is clearly indicated. In the long term the panel envisions an energy economy based on nonfossil sources, with electricity and hydrogen being the staple forms of energy dis- tributed to cities and industries. The transition from fossil fuels to synthetic fuels will occur when the total cost of producing and using fuels from nonfossil energy sources intersects the rising costs, including environ- mental effects, of coal and imported oil and gas. In the interim, hydrogen will be produced from fossil sources such as coal and from off-peak electricity via water electrolysis. 62-332 0 - 76 - 39 PAGENO="0610" Table 1. Comparative Characterisitics of Synthetic Fuels Heat of Boat of Holative fuel Density Boiling Ease of combustion, vaporization required to equal ue low heating at b.p. II l1oat content point storage6 O)~1C1d Liquid H Gas STP ~ value 4Btu/lb) (lb/ft3) (lb9ft3) (lb/ft3) ( 1) (Btu/lb) By wt By vol Hydrogen 51,6000 l9~t 1.0 1.0 (lip.) 4)4 1414 0.005 -1423 6 (lip.) I (112) 0.O~43 -28 14 Ammonia 8,000 590 6.14 o.6 l~2.6 7.8 (Nil3) 8.9 236 3 6 Ilydrazine 7,200 5140 7.2 0.5 62.14 (N2H}4) 1149 2 Methanol 8,600 14714 6.0 0.5 149.7 7.1 (CH30H) 6.5 0.0141 -259 5 (liq.) 2 Methane 21,500 220 2.14 O.~4 25.9 (~il~4) 173 1 3 Ethanol 11,600 360 14.14 0.~i 149.7 6.5 (C2H50H) - 257 (1) (ii) GasolineC 19,100 1140 2.7 0.3 143.8 7.0 (081118) 0Density of hydrogen in the fuel. 6flelative ranking. Clncl44dod for referenco only. PAGENO="0611" 605 The research, development, qnd demonstration program outlined below is recommended for federal government sponsorchip. While some of the important goals can be identified now, a more detailed analysis of the alternative development paths should be undertaken before commitmen~t to a major effort in order to arrive at the moat effective program from a standpoint of cost. Critical Related Issues To better define the priority and urgency of such a program, several other evaluations should be made and a number of policy issues should be resolved. The real cost of environmental effects should be determined so that the environmentally beneficial characteristics of synthetic fuels can be evaluated and compared with other alternatives and with the environmental effects of their production processes. Other critical policy issues to be renol~jed are mainly related to our increased dependency on foreign energy sources, that is, dependability of supply, the impact on national security and balance of payments, and the' possibility of arbitrary pricing by foreign interests. There are also serious policy issues related to the need for, or the desirability of, imposing controls on the rate of growth of energy demand. The future use of coal as a source of gaseous and liquid fuels was also identified as an important factor in determining the urgency and the level of effort to be placed on developing fuels from nonfossil sources. Since a time constraint, plus originally a basic ground rule for this panel's study, pre- vented detailed examination of the use of coal, answers to many highly relevant questions were not available; for example, questions of the ultimate costs and total environmental impact of producing hydrogen, methane, or methanol from coal and questions relating to the extent of our economic resources relative to their possible future use in supplying gaseous and liquid fuels. A related problem, also somewhat beyond the primary scope of this panel's work, is concerned with the citing and construction (including capital avails- hi 1. ly) a I 00 III ci emit hue teat, nolur, etc. , lieu U:; to 1i0V Ii: UJIC J)h namury energy required to produce the synthetic fuels. Just to meet one-half of the projected transportation fuel needs for year 2000* with electrolytically produced hydrogen would require an additional electrical generating capacity of nearly 1,000,000 MW or about 2 1/2 times the currently expected nuclear *ttThus decreasing projected petroleum imports by about one-half and realizing - a substantial savings in foreign exchange. PAGENO="0612" 606 generating capacity at that time. 2aking lull use of the available off-peak nuclear power in the year 2000 could reduce the required generating capacity by about 20%. To use coal in a gasification plant to produce this curse transportation fuel need, would require about 1.3 billion tons of coal or more than double the current production rate. Another possible strategy for relieving the demand for imported fuels, but also not considered to be within the scope of this panel's work, would be to substitute electricity for some selected fuel uses. As an example, if the residential and commercial space heating load projected to be met by gas and oil in 2000 were to be met by electricity, additional electrical generating capacity of 300,000 MW would be required. This alone would represent a 35% increase in the nuclear generating plant capacity planned for this time period but would release sufficient oil and gas to provide about 30% of the total transportation energy need. It is further important to recognize that keeping up with energy demands without introducing new alternatives is in itself costly. It has been estimated, for example, that the cost of developing additional fossil resources and import foreign fuels would cost about $110 billion (at 1912 price levels) by 1985. In view of the enormity of the future energy problems facing the U.S., it is believed that promising options should be kept open by instituting vigorous research and development programs. A particularly important future option is believed to be in the area of nonfossil synthetic fuels. Conclusions The results of an assessment of the various sections of a synthetic fuel based system are summarized as follows. Fuel Production. The process (nonfossil) most likely to be used for the large-scale production of hydrogen is water electrolysis. With further research and development, efficiency increases of 25% and plant cost reductions of ~5% appear po~sible. large economic improvcaen La would also result I S Large rsarko Lm3 for time by-products, oxygen and deuterium, could be found. The thermochemical production route has not been developed past the labora- tory stage but could be an attractive long-range method. Padiolytic and direct thermal decomposition of water do not seem to offer attractive commercial possibilities. Several biological production schemes should, however, be further investigated to establish technical feasibility. PAGENO="0613" 607 As indicated above, obtaining fuels from urban and agricultural wastes reprenente an attractive development area. Production of hydrogen or methanol from coal appear Lu be developed processes, although no large plants have yet been built. Corrimercial imple- mentation scone to be largely dependent on economic factore, but with current prices for coal, hydrogen from this source would b.c about one-half as costly as that from water electrolysis. Use of the western lignite deposits for hydrogen and methanol production appears to offer a number of advantages and should be further evaluated. Table 2 summarizes current and projected production costs for the various synthetic fuels considered. Storage and Transportation. The technology of large-scale storage and transportation of hydrogen and other synthetic fuels appears to be generally well developed. The use of underground aquifers or depleted gas wells for storage of hydrogen is, however, an area requiring further work. Small-scale storage, particularly for mobile energy, is one of the priority areas for further development. In addition to liquid hydrogen, compounds of hydrogen or hydrides offer attractive storage possiblities. Preliminary indications are that the costs for pipeline transmission and local distribution of hydrogen will be slightly more than those for natural gas; however, gas transmission and local distribution cost is less than one-third the cost of a corresponding conven- tional electric system. There is a need, however, to develop more precise cost estimates on a consistent basis for the transmission and distribution of electricity and hydrogen so that more definitive systems analyses can be made. Fuels Utilization. Hydrogen appears to be readily substitutable for other fuels and in most cases yields real benefits, particularly in reduced environ- mental degradation and increased energy use efficiency. The need for government- supported research and development appears to be relatively small in the urban use sector, although eventual support for demonstration mi conversion efforts would require significant funding levels. Industrial uses for hydrogen are growing and could expand greatly if hydrogen were available at a price suitable for other industrial fuels and would yield substantial environmental and efficiency advantages. Its use in the industrial sector does not appear to require significant, direct government support for research and development. work. Adapting synthetic fuels to transportation uses, particularly hydrogen for aircraft and automobile use, represents an area where research and develop- ment is needed. Fuel logistics, on-board storage, and power conversion are PAGENO="0614" Table 2. Summary of Synthetic Fuels Production Cost in 1972 Dollars0 Fuel Fossil-based Process Fuel Cost ($1106 Otu) . Electrical (or other) based Processes Fuel Ccci (~/1Q6 B~u) Hydrogen Natural gas, 40/1103 ft3 97 Water electrolysis Coal, $7/ton 132 Power, 8 aills/kWhr 368 Lignite, $2/ton 78 Advanced technology, 8 rnills/kWbr 233 (Liquefaction 150) Advanced technology + by-product credits, 8 isills/kWhr 0ff-peak power, 2.5 mills/kWhr 17~ 155 Ammonia Natural gas, 1~5//l03 ft3 157 H~ via 1120 olectrolysin, 8 mills/klihr 112 via 1120 electrolysis, 2. 5 mills/kWhr 517 288 Hydrazine a2lOO Methanol Natura]. gas, )~0//l03 ft3 158 112 via ~2° electrolysis, 8 mills/kElir (CO2 from air) c550 Coal, $7/ton (c27//106 Btu) lEO . Lignite, $2/ton (~l5//l06) %l25 Btu) Ethanol Petroleum feed stocks aE6O Fermentation from corn, $1.25/bu 880 Methane Well-head gas 15 - E0 Urban and agricultural wastes ~1i5 LNG, imported 80 - 100 Coal 80 - 100 Gasoline Crude oil 105 0Costs are based on 15% fixed charge rate and large plant capacities. PAGENO="0615" 609 specific areas requiring further work. jr ejectrleaj generation, fuel cello and turbines would both benefit from the ise of hydrogen, or hydrogen and oxygen, but both systems need further development. Systems Considerations. Based on preliminary systems analyses, indica-. tions are that nonfossil synthetic fuel systems can overcome many of our long-. term energy problems, although further analyses are required to establish the timing and urgency of implementation. It is likely that synthetic fuels from fossil sources (coal, oil shale, etc.) will be less expensive in the near term but, as the more attractive coal deposits are depleted, the synthetic fuels from nonfossil sources should become generally economically competitive. As indicated in Fig. 2, recent estimates of the extent of the world coal resources suggest that the maximum rate of utilization of coal may occur between the years 2030 and 2070, at which point approximately 50% of the available resources will have been depleted; however, other estimates predict the peak occurs much further out in time. Obviously, the position of this peak shifts closer to the near term if coal resources are used in the manufacture of synthetic fuels. Thus, it is important to establish the lifetime of our fossil fuels so that, sufficient research and development lead time is available to anticipate the introduction of nonfossil synthetic fuels in the energy economy. For some specialized applications or environmental advantage, electrolytic hydrogen produced via low-cost, off-peak power, or perhaps from remote hydropower, will be competitive on a near-term basis. Systems analyses comparing an all-electric energy system and a combined electric-hydrogen supply system for residential consumption show that the combined system can be more economic. Advantages result primarily from relatively low gas transmission and distribution costs and high load factor operation of the primary nuclear power plants. The primary energy source for the combined system, however, must be about 25% larger to deliver the same total energy. Thus any costs associated with waste heat disposal or the handling of increased amounts of waste products must be weighed against the environmental and convenience advantages of synthetic fuels. As a storable energy form, hydrogen may find near-term use as an alternative to pumped-hydro storage systems. This may be especially attractive if accomplished in connection with other uses of hydrogen, for example, in the transportation sector. A power plant devoted at least partly to producing electrolytic hydrogen could also be used to provide peaking power by decreasing the rate of hydrogen production. PAGENO="0616" cc >~ 3 QJ co 0 z 0 I- U 3 a 0 cc 0~ 0 F- cc 610 ORNL DWG 72-10355R 2L00 CALENDAR YEAR FiEure 2. Projection of Fossil Fuel Production (from 2. A. Elliott and N. C. Thrner, 1972) PAGENO="0617" 611 Gurosary 0 Recommended Research and Developaen Applications of synthetic fuels and the associated research and development requirements were divided into two categories: those which can have a near-tera, by 1985, impact on the nation's energy problems and those which would be of significant impact after this date. The near-terms tasks which were identified are: 1. development and demonstration of methanol from coal as an automotive fuel, 2. development and demonstration of H2 produced from coal for use in the industrial sector both as a chemical and as a fuel, 3. development and demonstration of H2 as an energy storage medium for electric utilities use in supplying peak power demands, 8. development and demonstration of the production of gaseous and liquid fuels from urban and agricultural waste products. Assuming a reasonable funding level, these programs are projected to require up to a five-year research and development effort. The methanol task would establish the technology mmd economics of both the production from coal and/or lignite as well as the end use in automobile engines. Since auto trans- portation represents the biggest single user of petroleum, the successful imple- mentation of this program could have a significant impact on the oil-import and air pollution problems. Tasks 2, 3, and 8 also appear to have near-term viability and would likewise relieve the demand for natural gas and petroleum. The research and development program identified to achieve the longer- term impact is as follows: 1. use of hydrogen as a transportation fuel, particularly for aircraft and for specialized ground vehicles; 2. hydrogen production investigations; 3. long-distance transmission and bulk storage of hydrogen; 8. pubLic ;rLfety a tedium; 5. overall cystems analyses. It is estimated that a five- to ten-year research and development program would be required to establish the feasibility of using hydrogen as a trans- portation fuel. This program would give particular emphasis to fuel tankage and logistics and their interrelationships to engine and frame considerations. Hydrogen production investigations to improve the water electrolysis process, as well as to investigate new methods such as thermochemical and biological, could involve a five- to ten-year program. PAGENO="0618" 612 Long-distance transmission and bulk storage of hydrogen, including system studies, design optimizoW] ens, and cornpaacnt development, are estimated to require a continuing effort of at least five years. Public safety and overall system analysts are envisaged as long-term relatively low-level efforts, but onos which arc essential to a smooth iaple- mentation period as well as to form the base for a well coordinated research and development program. It is expected that most of the long-term tasks will require concerted work well beyond the intial feasibility efforts outlined above, but will depend strongly on the results obtained by the end of the research and development period. In general, the panel concluded that the main obstacle to the use of hydrogen as a universal fuel is an economic one, and that an extensive and long-range research and development Drogram could do much to narrow the gap between its cost and the cost of fossil fuels. The cost of fossil fuels, because of declining resources and increasing enviroaaental protection require- ments, should increase at a higher rate than the cost of producing the synthetic fuels, and this will also contribute to improving the relative economic position and shortening the implementation period for the adoption of the hydrogen-based economy. It is clear that our fossil fuels will ultimately be depleted and that reliance must then be placed on the nonfossil synthetic fuels. When this will take place or when a transition from coal based to nuclear- or solar-based fuels should begin is suggested as a topic for a future more detailed study. However, Fig. 2 indicates one case of assumed utilization of the U.S. coal resource and a projected rate for implementing a synthetic fuel economy. If one assumes a reasonable time to complete research and development programs and then to implement a new fuels systems, it is evident that by making a strong research and development commitment now followed immediately by a ((,rIce 5 ted 51~ (~Tfl~Fl tat. Ofl rrof'ain I I. dioul t 1)0 [)C)5 1)1 1: .1 tow the row 1:1:1 tern available to meet our long-term needs. PAGENO="0619" 613 APPENDIX The following moabers of the study panel on nonfossil synthetic fuels and fuel cells, together with other contributors listed below, were respon- sible for the preparation of this report. The work was, sponsored by the AEC under the copnizance of the Division of Reactor I)evelopment and Tech- nology. PANEL ORGANIZATION J. P. Michel F. J. Salzano E. Hammel A. L. Austin D. P. Gregory J. E. Johnson C. F. Williams W. J. D. Escher J. Braunstein ORNL BNL LASL LLL Institute of Gas Technology Linde Div. of Union Carbide Teledyne Isotopes Escher Technology Associates ORNL Panel Leader Systems Analysis Urban Uses of Hydrogen Hydrogen Use in Automobiles Uses of Synthetic Fuels Fuel Storage and Transportation Electrolysis Transportation and Electric Generation Thermochemical Production CONTRIBUTORS W. Hausz ~ C. C. Burwell G. C. 0. Leeth Meyer General Electric, i. H. Spiewak E. Goeller P. R. J. Lueckel J. Dufour Pratt & IGT Whitney T. J. S. Mackey M. Holmes ORNL C. Marchetti EURATOM G. B. Hovelli G. K. P. M. Blouin C. Hoffman A. Sevian TVA BNL BNL S. F. 0. S. Kirslis F. Blankenship L. Culberson ) F. J. Edeskuty LASL 5ORNL - Oak Ridge National Laboratory BNL - Brookhaven National Laboratory LASL - Los Alamos Scientific Laboratory LLL - Lawrence Livermore Laboratory Individual Affiliation* Area of Responsibility PAGENO="0620" 614 Statement of Harvey A. Proctor Group Vice President, Oil and Gas, Pacific Lighting Corporation and Chairman of the Board Southern California Gas Company Los Angeles, California and Chai rman Research and Development Executive Comittee American Gas Association Washington, D.C. Concerning the Hydrogen Energy Potential Hearings Filed with the Ii. S. House of Representatives Science & Technology Coninittee Energy, Research, Development and Demonstration Subconinittee Washington, D.C. June 27, 1975 PAGENO="0621" ?d5 Statement of Harvey A. Proctor Filed with the U.S. House of Representatives Science & Technology Committee Energy, Research, Development and Demonstration Subcommittee June 27, 1975 Mr. Chairman and Members of the Committee: Thank you for providing this opportunity to express the views of a major sector of this country's energy system concerning the potential of hydrogen energy. Before I discuss hydrogen, I would like to make a few statements regarding the gas industry's position in the energy field and cite a case study as an example of our present situation. We know that our country faces what may be the most serious and far- reaching crisis in its history -- the availability of energy. As to the natural gas sector, there is now a clear threat to the maintenance of adequate service to approximately 160 million people who are served through nearly 44 million meters on the country's gas distribution utility systems. Only a small number of these premises are equipped to switch to an alter- nate fuel.. The remaining consumers face extended disruption of energy availability in the relatively near future with anything less than an im- mediate, all-out national effort. The intermediate and long term situation are just as critical with respect to energy planning. In my statement, I will use my company's operations as a case study of the gas industry's present situation. Pacific Lighting Corporation is a Los Angeles-based holding company -- our principal subsidiary is Southern California Gas Company. SoCal Gas is the nation's largest gas distribution utility, serving one out of every thirteen of the nation's gas customers. The area we serve has for many years been heavily dependent on natural gas PAGENO="0622" 616 as its primary source of energy. Pacific Lighting also has several gas supply subsidiaries whose primary function is to acquire new supplies for So. Cal. The map in Appendix show the extent of our search for such new supplies. We are, therefore, very familiar with the problems faced by both the nations gas distribution utilities and gas supply companies. Also included in the Appendix is a chart illustrating our market requirements and supply. By 1979 gas supply from present sources will be inadequate to meet essential firm, i.e., mostly residential, requirements. Almost all gas distribution utilities face a similar supply deficiency, with only the extent of the problem varying somewhat because of regional differences. To solve our problems for the short term and not plan for the long term would be a serious error. As a result of the energy shortage, we now know that the gas industry plays an important role in this country's energy balance. We also know that the gas industry will be relying more and more on substitute natural gas from fossil fuels in the future -- which in itself is limited. What we need then is to consider, today, what ideal gaseous fuel, for the future, would be economically viable and environ- mentally acceptable for long term planning purposes. There appears to be sufficient evidence today to say that hydrogen has the potential to meet these criteria. I will summarize my presentation and then discuss more fully the following: the importance of gas energy in the nation's energy balance; the need for hydrogen as a fuel in the future; the future outlook for hydro- gen; hydrogen production; hydrogen transmission, hydrogen storage; hydrogen utilization; hydrogen safety; and recommended hydrogen research. -2- PAGENO="0623" 617 Suninary of Harvey A. Proctor Statement Natural gas provides about 40% of all the domestic energy production consumed in the United States. It is a premium, clean burning fuel, pro- viding basic energy service to approximately 160 million people. This fuel is now in short supply. Curtailment by interstate pipelines will soon reach 2.5 trillion cubic feet per year -- equivalent to the energy generated by all the nation's hydro and nuclear plants. Between now and 1985, the gas industry must develop every possible source of gas to offset this decline. These efforts must include 1) maximum exploration for and development of lower 48 sources, 2) synthetic gas from coal, 3) gas from Alaska, 4) imported LNG, and 5) synthetic gas from liquid feedstock. Because of the limited supplies of fossil fuels available, our energy supply pattern will undergo some radical changes in the near and distant future. One change is that energy in any form is going to cost more in proportion to the other things we can buy. Another change is that the sources of energy which we use will have to change and relatively inexhausti- ble'1 supplies such as nuclear or solar energy will have to play an increasing part. These changes will precipitate a number of other radical changes, which themselves will be tempered by our increasing desire to avoid "pollution" or to minimize the effects of our technological progress upon our environment. One of the changes that is possible is the development of a fuel system based upon a synthetic chemical fuel derived from nuclear or solar energy and fully recycleable materials such as air and water. Of the various fuels that can be considered, the one that appears to have a high potential is hydrogen. -3- PAGENO="0624" 618 The feasibility and introduction of such a system will not be without major problems, many of which will require fairly long lead times for their sOlution. In this regard further research is needed in the areas of hydrogen energy production, transmission, distribution, and utilization system that may ultimately take the place of the present natural gas system when our fossil fuel supplies become scarce. -4- PAGENO="0625" 619 I. The Importance of Gas Energy in the Nation's Energy Balance The need to gain the greatest possible degree of energy self-suf- ficiency in the immediate future is well recognized. In working toward that goal, the part that gas plays must be brought into clear focus. Natural gas is the dominant domestic energy source. It provides about 40% of all domestic energy production consumed in the United States -- by contrast, domestic oil provides about 30% and coal about 21%. Hydro, nuclear, and geothermal sources provide less than 10% of our domestic energy. Yet, attention is generally focused on the oil problems of the country or on the problems faced by the electric industry in meeting its financial and fuel requirements. Our industry's problems and needs can no longer be ignored, if this country is to maintain its position as the world's leading industrial nation, and if our citizens are to maintain an acceptable standard of living. Natural gas performs functions which are basic to the needs of residential, commercial and industrial consumers. In the home, it pro- vides energy for cooking, water heating and space heating. Across our nation over 100 million gas furnaces, water heaters and ranges are in use. Gas must continue to be available to serve these appliances in which Americans have invested many billions of dollars. These gas appliances, while providing safe, economical service to their owners, also conserve the nation's energy. The Council of Environmental Quality has appropriately reported that it takes over twice the primary energy to fuel an electric system supplying an all-electric home, than a gas system required to serve comparable energy needs. 62-332 0 - 76 - 40 PAGENO="0626" 620 In addition to residential energy needs, there are many commercial and industrial fuel requirements where there is no practical alternative to gas. Under today's circumstances, and with present Federal Power Com- mission regulation, low priority use of gas for boiler fuel has virtually disappeared, except for gas not subject to federal regulation. PAGENO="0627" 621 II. The Need for Hydrogen as a Fuel in The Future Many studies have been prepared dealing with our fossil fuel re- sources and undoubtedly many more will be done. Although many of these come to differing conclusions, they reach a broad consensus that each of the fuels -- gas, oil, shale, and coal -- will be produced at increasing rates until they each reach a peak, after which time, the rate of pro- ducibility will decline. The peak producibility of natural gas in the lower 48 U.S. states may be occurring now. Past studies of the problem on a worldwide basis have assumed various models for the rate of development of production and various estimates for the overall fossil fuel resources. In each case they show that peak producibility occurs in the first half of the 21st century, or within 50-80 years from now. That is not to say that all the worlds coal, for example, will have been used by then, but that the rate at which all fossil fuels can be produced will be falling off after that time, so that a new energy source must be found to fill the gap. The only new energy source with which we can `fill the gap," based on present and immediate future technology, appears to be nuclear energy. To produce the vast amounts of energy required in the future, the breeder reactor, and ultimately the fusion reactor, will have to be developed because the natural. uranium reserves are themselves limited in quantity. Solar energy may also be harnessed in the future. This is a critical area for advanced developments. Solar energy appears to have the highest poten- tial for large scale clean energy production. However, in this statement, I will confine my consideration of energy sources to nuclear reactors. The most important question is the form in which this nuclear energy is to be delivered to its users. Most of the current work on nuclear reactor technology is aimed at converting nuclear energy into electrical energy for direct supply to the -7- PAGENO="0628" 622 consumer. As problems of siting nuclear power plants, due to their heat release requirements and safety considerations, become greater, longer transmission lines will be required. The optimum size for nuclear power stations is also likely to become very large, about 5,000 to 10,000 MW, again requiring large, high-capacity transmission lines. Among recent developments in the nuclear industry is a growing interest in modular floating power stations, built by shipyard techniques and delivered to ocean-cooled offshore sites. In the U.S., the use of electric energy by the consumer is growing at more than double the rate at which our overall use of energy is growing. The growth rate of electricity now appears to be slowing, but is still pre- dicted to rise considerably faster than the direct use of fossil fuels. The impact of the growth of nuclear electric power stations will assist this trend. On economic grounds, such a trend is surp~'ising because electric energy, on the average, today costs much more than natural gas, for example. On energy conservation grounds, it is also surprising because for each unit of electrical energy reaching the consumer, about 3 to 4 units of fuel energy are spent for its generation and transmission. One of the biggest problems facing the electrical industry is the transmission of the huge quantities of electric power that will be produced by the remotely located generating stations to the concentrated urban areas where the load centers are. Apart from the high cost of transmission equip- ment and maintenance, there is growing concern for the aesthetic effect of overhead lines. Allied with this problem is one of storage requirements. - 8- PAGENO="0629" 623 At present, there is no way of storing large quantities of electrical energy near the consumer sites for peakshaving purposes. Of the various gaseous fuels considered, in the future, it would be to our advantage to confine ourselves to those made from air and water, so that on combustion their products can be deposited into the environ- ment without pollution. Of the choices available to us now, hydrogen appears to be the easiest to make and in many ways the easiest to use. Hydrogen is the cleanest of all fuels, burning to form only water, with the possibility, which may be suppressed, of nitrogen oxides forma- tion from the heated air. Apart from the absence of pollution, water is sufficiently abundant and mobile in the earth's crust that no disturbance would be caused by consuming water at the generating stations and liberat- ing it in the cities. We can, therefore, make a strong case for the potential of hydrogen as a gaseous fuel to eventually replace natural or substitute gas and the other fossil fuels as they become scarce or expensive. Let us now look into the technical problems associated with the production and use of hydrogen. . PAGENO="0630" 624 III. The Future Outlook for Hydrogen To set the stage for examining some of the problems to be solved, I will attempt to describe the energy situation 30 to 50 years from now, assuming that a hydrogen energy system was developing. This is the "broad outlook" approach of technological forecasting and allows one to foresee problems before they actually occur. In the future, hydrogen will most likely be produced from nuclear energy by today's known technology using water electrolysis. Direct- current electric power from a nuclear power station can be used to elec- trolyze water into hydrogen and oxygen at efficiencies of about 100% (in comparison to today's figures of between 60 and 70%). New methods may also be developed for water-splitting using the nuclear reactor heat directly. Hydrogen has the potential to be used for all the present applica- tions of natural gas and more. Burners can be designed to handle hydrogen in heating, cooking, and industrial operations. Gas turbines and piston engines have been proven to operate better on hydrogen. Fuel cells that use hydrogen as a fuel are simpler and cheaper than those that use hydro- carbon fuels. As I have already mentioned, hydrogen is an extremely clean fuel, the controlled burning of which produces only water. The benefit of such a clean fuel on the environment will be considerable. Hydrogen also has the potential to be transmitted from remote, possibly offshore, power stations in underground high-pressure pipelines similar to those used for natural gas today. In many instances, the existing lines can be used, with modifications to the compressor stations. There -. 10- PAGENO="0631" 625 appears to be no insurmountable problems in doing this. Hydrogen can also be distributed in networks similar to those used for todays natural gas. The cost of delivering energy in a natural gas pipeline distribution system is today far lower than the cost of moving electrical energy. This advantage of gas transmission appears to be retained if we eventually move to hydrogen. -li PAGENO="0632" 626 IV. ~y~rogen Production Let us now consider the present techniques for producing hydrogen from electric power and from thermal energy without the use of fossil fuels. The only such process currently available is that of electrolysis of water. Large-scale electrolysis plants are in operation in many parts of the world where relatively cheap electric power is available, mainly supplying hydrogen to the ammonia and fertilizer industry. None of these plants is as large as we are envisioning, but they are modular in con- struction and could be scaled up without problems. The efficiency of present plants is about 60-70%, based on the ratio of the fuel value of hydrogen produced to the electrical input. Because of the special thermodynamic conditions of water electrolysis, it is theoretically possible to operate a cell that absorbs heat from its sur- roundings and thus produces about 20% more hydrogen energy than the elec- trical energy supplied. In practice, it should be possible to develop a plant that would operate at an apparent 100% efficiency, based on electrical input, and still allow some irreversible electrode losses. Another means of producing hydrogen is by thermochemical water-split- ting to avoid the costs and inefficiencies of producing electricity. By this process, water enters into a series of chemical reactions that consume heat energy directly from the nuclear reactor. Hydrogen and oxygen are among the products of the reaction sequences. All other products are com- pletely recycled within a closed loop. Theoretically, the efficiency of a single thermal water-splitting process can reach 85% and is not subject to the same restrictions that control the efficiency of nuclear-electric power stations. - 12 - PAGENO="0633" 627 V. Hydrogen Transmission Hydrogen is transported in chemical plants today in huge quantities through pipes operating at up to 1200 psi. The U.S., Germany, and South Africa operate pipeline systems using pipes up to 12 inches in diameter and pressures up to 450 psi, over distances of 50 miles or more. One network of hydrogen pipelines in Germany totals about 130 miles. At this point in time, we have found no reason to suppose that exist- ing pipeline materials are not compatible with hydrogen. Hydrogen inter- granular embrittlement does not occur at the typical temperatures and pressures experienced by pipelines, except in the presence of "atomic hydrogen" produced, for instance, by corrosion processes. Molecular hydro- gen under pressures of up to 2000 psi, at room temperature, does not affect carbon steels at room temperature. We have, however, found reference to a new phenomenon, known as "environment embrittlement," observed and being studied by NASAs research laboratories. This is a surface-fracture phe- nomenon associated with the presence of very high purity hydrogen at high pressures on a steel surface subject to yielding stress. Whether or not this is cause for concern to pipeline design requires further study, but it does not appear to have caused problems, for instance, with either the U.S. or German hydrogen pipeline systems, the latter having been in con- tinuous operation since 1940. We have investigated the energy-carrying characteristics of an exist- ing natural gas pipeline as if it were converted to hydrogen. As a result, we have found that the capacity ratio of the pipe itself varies with pres- sure, but is only slightly less for hydrogen than for natural gas at 750 psi (this is due to the different compressibilities of hydrogen and natural - 13 - PAGENO="0634" 628 gas). We also found that the existing compressor capacity would be in- adequate to handle the extra volume required to carry the same energy; thus the pumping horsepower would also have to be increased. In suninary, an existing line, without modification, operating on hydrogen would carry only 26% of the energy, but would require only 10% of the compressor horsepower, as with natural gas. To carry the same energy content as hydrogen, at the same pressure of 750 psia, the compressor capacity would have to be increased by about 4 times and the horsepower by about 6 times. Considerable advantages, especially in horsepower requirement, result from operation at increased pressures. Compressors specifically designed for hydrogen will be different from those for natural gas. Multi-stage compressors would be needed because achieving a high enough compression ratio in a single-stage radial compressor will present a problem. Axial turbocompressors are attractive for very large volumes. The screw compressor, not normally used at high pressures, would combine the benefits of positive displace- ment with high throughput and low capital cost. An interesting possibility exists for combining a liquid-hydrogen transmission pipeline with a superconducting cable carrying electric power. Liquid-hydrogen transmission alone appears to be prohibitively expensive, as does a helium-cooled superconducting power line, but as a long-term possibility, a combination of the two may have merit. - 14 - PAGENO="0635" 629 VI. j~ydrogen Storage One of the great advantages of the hydrogen energy form over elec- trical energy is its capability of storage on a large scale, as is required for peakshaving on a daily and seasonal basis. Line-packing will probably be unimportant as a storage technique for hydrogen because the pipeline will contain only about one-quarter of the energy as a natural gas line at the same pressure. Compressed gas storage in high pressure tanks appear to be prohibitively expensive on all but the smallest scale. In addition, liquid-hydrogen technology has grown rapidly as part of the space program. On the other hand, underground storage of hydrogen in depleted oil and gas fields, in aquifer storage, and in mined caverns all appear to be economical and practical. If these fields are gas-tight for methane, they will be gas- tight for hydrogen, as the seal is accomplished by a water capillary effect and is independent of the nature of the gas. - 15 - PAGENO="0636" 630 VII. Hydrogen Distribution A public distribution system for pure hydrogen does not exist at present, although the vast experience with manufactured gas, which con- tains up to 50% hydrogen, is valuable and suggests that the concept is feasible. Because operation is at relatively low pressure and flows are laminar rather than turbulent, the increased requirements of a transmis- sion system do not apply to a distribution system. The capacity on hydro- gen of an existing system operating with the same pressure drops would be within 6% of its capacity on natural gas. Most existing materials are compatible with hydrogen. Although the permeability of plastic pipes is from 5 to 85 times higher for hydrogen than for methane, according to materials, the absolute loss rates are insignificantly small, from both a cost and a safety consideration. Existing codes for gas distribution systems will apply equally to hydrogen systems, with the exception of one of the National Fire Codes, which prohibits the use of cast iron pipe for hydrogen service. - 16 - PAGENO="0637" 631 VIII. j~ydrogen Utilization Hydrogen will be primarily used to produce heat by combustion. We have reviewed the combustion characteristics of hydrogen and compared them with those of methane. The most dramatic differences are in: 1) flame speed, 2) ignition energy, and 3) upper flaniiiability limit with air. The first of these differences requires that the burners now in use for natural gas must be modified, but the extent of the required modifications can be accurately predicted, and the feasibility of modifying each type of burner can be evaluated in advance. The second difference results in easier ignition systems and more stable flames. Hydrogen offers a great opportunity for novel appliance concepts because it is admirably suited to catalytic combustion. At temperatures from 1000 F upward, hydrogen will oxidize in air completely on a catalyst surface. Catalytic radiant and convective heaters are possible. The cleanliness of the fuel allows its combustion without a flue. At the lower temperatures of catalytic combustion, no nitrogen oxides can be formed, so water is the only product. Novel domestic heating concepts can be devised, using a single ventilator in the house to control the overall humidity produced by individual heating devices in each room. Much higher efficiencies than conventional gas burners are thus available. Research is needed to develop these catalytic burner concepts into useful hardware, especially in the area of inexpensive catalysts and ignition systems. Of the other equipment on the customers' premises, only the meter needs modifying, as it will have to carry 3 times the volume of gas. - 17 - PAGENO="0638" 632 IX. Hydrogen Safety The most controversial subject concerning the use of hydrogen as a fuel is its safety. We have examined this in considerable detail and have compared its hazardous properties with those of natural gas. Our conclusion is that, because of the hazard, so much work has gone on in industrial hydrogen safety that we now know how to achieve the same safety standards as we obtain with natural gas. In fact, several features of hydrogen make it safer than some of the materialswe handle routinely today. Its low density and high dif- fusivity ensure that leaking hydrogen diffuses quickly. Its low heat- ing value means that the energy buildup in a confined space is less than that of methane or propane. There are well-established and rigid codes of practice for hydrogen handling, both as a gas and as a liquid. - 18- PAGENO="0639" 633 X. Recommended Hydrogen Research We suggest that serious consideration be given to the development of hydrogen energy systems for the future because it appears to have many advantages, both in economics and in environmental attractiveness. In this regard, certain research remains to be undertaken or continued. The following research objectives should be established, some of which can be delayed for attention at a later date: 1. Production a. Increased efficiency of electrolysis cells b. Decreased cost of electrolysis cells c. Systems optimization of nuclear-electric-electrolysis power stations d. Expanded research on new thermochemical water-splitting processes e. Engineering studies of practical means to harness solar energy to make hydrogen 2. Transmission a. Detailed pipeline optimization studies aimed at identifying compressor design requirements b. Compressor development for optimum hydrogen service c. Study of the `hydrogen environment embrittlement" pheno- menon under conditions associated with transmission pipe- line operation d. Preliminary design and cost studies on liquid-hydrogen pipelines carrying cryoresistive or superconducting electric cables 3. Storage a. Detailed operational plan for a pilot scheme for underground storage of hydrogen in a depleted gas field or in aquifer storage - 19 - PAGENO="0640" 634 b. Basic research on metal hydrides, with special regard for reducing the heat transfer load during charge and discharge c. Engineering-economic studies on intergrated hydride storage systems to allow use of the hydride heat energy released on charge d. Investigation of the practical feasibility of constructing large-scale cryogenic hydrogen tanks without vacuum insulation e. Investigation of means to reduce the cost of hydrogen liqué- faction and storage 4. Distribution a. Experimental studies of pipe-sealing materials in hydrogen envi ronments b. Experimental tests of leakage characteristics from various types of pipe failures including joints, corrosion pits, and fractures in pipes carrying hydrogen. c. Life tests for possible degradation and peniieability checks on plastic pipe in hydrogen service d. Selection of suitable odorants and leak detectors for hydrogen e. Selection of suitable flame illuminants for hydrogen 5. Utilization a. Experimental survey of existing domestic and industrial burners converted to hydrogen service b. Experimental development of inexpensive catalysts and catalytic appliances for domestic and industrial use c. Development of appliances not using catalytic burners that are fueled with hydrogen d. Investigation of feasibility of converting existing meters to operate at 3 times the volume flow rate e. Analysis of an inexpensive and efficient hydrogen-air fuel cell 6. Safety a. Construction of suitable demonstration systems b. Use of demonstration equipment by gas company maintenance crews to explore problem areas and to create confidence - 20 - PAGENO="0641" 635 c. Use of demonstration equipment to test new equipment d. Preparation of Hydrogen Safety Manual for use by gas industry personnel e. Review of existing local and national codes to determine if they are strict enough to ensure safe operation on hydrogen 7. Systems Studies a. Construction of large-scale demonstration energy trans- mission system, using coninercial electrolyzer, commercial pipeline components, modified "coninercial' electric generator, and other hydrogen-using equipment b. Long-term use of a hydrogen pipeline/compressor/distribu- tion equipment sequence in a closed-loop operation to demonstrate experience and confidence in handling hydrogen - 21 - 62-332 0 - 76 - 41 PAGENO="0642" POTENTIAL GAS SUPPLY SOURCES Pacific Lighting Companies 0 Ų~J LEGEND: 1. South Alaska 2. North Slope Prudhoe Bay 3. Mackenzie Delta 4. Canadian Arctic Islands 5. Coal Gasification 6. U.S. Joint Drilling Venture 7. California Offshore 8. Central and South America 9 Australia Offshore 10. Indonesia 11. Persian Gulf 12. Russia M~reh, 1975 PAGENO="0643" 637 CURTAI LMENT Electric Utility D Industrial 0 Firm* SUPPLY 0 ~ Residential and other small industrial and commercial consumers not equipped to use alternate fuel SOURCE 1974 California Gas Report M3c1/yr. Pacific Lighting Utilities GAS SUPPLY-REQUIREMENTS COMPARiSON PRESENT GAS SUPPLY SOURCES ~RECQRDED~1~~ ESTIMATED PAGENO="0644" 638 A VIEW OF HYDROGEN ENERGY SYSTEMS F.J. Salzano, and K.C. Hoffman We have had an active program for several years at Brookhaven in the area of hydrogen energy systems. Hydrogen is currently a very important element in the United States energy supply system, primarily as an industrial fuel and chemical, and we believe that this role can be expanded, as appropriate,, within the industrial sector and to other sectors through a carefully planned research and development program. Unfortunately, much of the public dis- cussion of this option has focussed on the concept of "Hydrogen Energy Economy". We are not enthusiastic, even in the long term, about any energy system that is based primarily on one secondary energy form, whether that form be electricity, hydrogen or methanol. The energy system must be diverse, using secondary energy forms that are appropriate to the supply or demand sector. In some cases elec- tricity will be preferred, while in others a fuel form based on hy- drogen such as methane or methanol, will be more appropriate. Below is a statement expressing our view on the Hydrogen Economy Concept. Brookhaven National Laboratory has been involved since the mid-l960's in research related to the utilization of hydrogen and has worked with liquid hydrogen in connection with bubble chanther facilities since our first large accelerator was built. Our systems analysis people have done a significant amount of work during the last few years on the value of hydrogen to the United States energy system and the merits of the Hydrogen Economy Concept. It is clear to us that hydrogen now plays a major role in the energy system in connection with the processing and manufacturing of chemicals, fertilizers, and foodstuffs, aside from the use in PAGENO="0645" 639 the refining of petroleum products. We believe that the role of hydrogen will increase arid become more significant as supplies of natural gas, the traditional source of hydrogen, become less abun- dant. We believe that hydrogen will play a najor role in the energy system as the level of nuclear capacity, solar, or ultimately nuclear fusion sources become available. Hydrogen in the near term can be vely important if it were to be produced by the electric utilities, as this allows a diversification of the product line, i.e., electricity. Clearly, electricity is not the best, most eco- nomic, convenient, flexible, or the most storable form of energy for all applications. This diversification of the electric utility product line, if it is encouraged, will ultimately allow nuclear, solar, or fu- sion energy to flow into both the nation's gas and electric sys- tens to the end use demands in the industrial, transportation, commercial, and residential sectors. This may be especially impor- tant to the industrial community which has previously relied on natural gas as a source of hydrogen. It is obvious that hydrogen is not desirable in all end use applications. Electricity is certainly a clean and convenient form of energy for some purposes. We believe that the energy system will evolve to accept a significant amount of hydrogen which could be delivered in an alternative distribution system as natural gas is delivered today. The basic question is the ratio of hydro- gen to electricity in the nation's energy supply system. As it is generally described we do not subscribe to the simplistic view of the Hydrogen Economy Concept, where hydrogen becomes the only or the most dominant energy supply medium. Hydro- gen cannot save the United States from the impending energy supply crisis facing the nation in the future; however, it can add an element of diversity, flexibility, economy in some cases, and some ~ PAGENO="0646" 640 environmental benefits when used for selected applications. It has a special application in connection with solar as it allows the production of fuel from solar energy. It is our belief that hydrogen will find initial application in the electric utilities as an energy storage medium convertible to electricity, or which can be injected in small concentration into the natural gas supply to supplement that declining resource. As the utilities gain experience with hydrogen they will be encour- aged to develop markets outside the utility system. This situation will gradually arise as more nuclear, and perhaps solar (wind also) electric sources are available. This is our view of the role of hydrogen in the energy system. Clearly, in the future when all fossil resources are gone, hydro- gen and electricity will play a side by side role in the United States and world energy systems. It is to the above ends that Brookhaven has in progress major programs to develop and encourage commercialization of the storage of hydrogen via metal hydrides and advanced methods of electrolytic production. In these programs the emphasis is on electric utility applications, reflecting what we see as the near term starting point and the source of excess electric capacity. Our systems analysis group is continuing its efforts to examine the prospective role of hydrogen in the energy system to determine the best and most natural fit. Other such efforts to identify where hydrogen has a unique role to play should be encouraged. It appears that ERDA has initiated a broadly based program in the area of hydrogen research and development and we believe this to be an important option that can increase the flexibility of the United States energy system. In our view it is very important that ERDA continue to develop the research base upon which the commercial development PAGENO="0647" 641 of hydrogen technology will depend. This includes the range of technology options required for economic production and storage primarily, and secondly, transmission, distribution and utilization related to the optimal use of hydrogen in the United States energy system. The emphasis in the early stages of this program should be on the R&D that will provide a firm technical basis for hydrogen energy systems including electrolytic and production from coal, improved storage in liquid form and as metal hydrides, and utili- zation in turbines and fuel cells. PAGENO="0648" 642 Sandia Laboratories Livermore. California 94~5O August 13, 1975 The Honorable Mike MCCOnTIaCk Conimittee on Science and Technology U. S. House of Representatives Suite 2321, Raybum House Office Building Washington, D. C. 20515 ~4yr dear Mr. MCormack: In response to your request for infonnation to be included in the printed record on the hearings on hydrogen on June 10 and 12, 1975, I sin submitting the following brief discussion. Mst of this information was nentioned at the hearing on June 10, 1975. Hydrogen Pipelines The feasibility of converting all or part of our existing natural gas pipeline systems to hydrogen is a controversial subject. We know that pipeline steels are degraded in properties by hydrogen, yet there are examples of small pipelines that have been used successfully. In my opin- ion, the controversy can be resolved if both laboratory and field testing are done to determine the tolerance level for defects in the materials to be used. The defects of importance include metallurgical flaws, weld defects, and defects caused by corrosion in the ground. Existing under- ground pipelines are not the only applications of interest. Hardware for new processes should also be considered, such as supply or transfer piping for hydrogen used in coal conversion processes. It is technically feasible to modify existing pipeline systems and future designs for added protection against hydrogen embrittlement. Liners or coatings on the inside of the pipeline can be used. Upgrading of com- pressor parts and the addition of gaseous inhibitors to hydrogen are other possibilities. These ideas are under study at our Laboratory and elsewhere. Sincerely yours, James H. Swisher, Supervisor Exploratory Materials Division Copy to: A. R. Lathgrebe Division of Conservation Research and Technology U. S. Energy Research and Development Administration Washington, D. C. 20545 H. J. Saxton, 8314 PAGENO="0649" 643 R.H. Wentorf, Jr. Power Systems Laboratory Report No. 75CRD119 May 1975 GENERALS ELECTRIC GENERAL ELECTRIC COMPANY CORPORATE RESEARCH AND DEVELOPMENT Schenectady, N.Y. HYDROGEN GENERATION by TECHNICAL INFORMATION SERIES 1 CLASS PAGENO="0650" 644 GENERAL* ELECTRIC General Electric Company Corporate R.t.arch and Development Sch.n.ctady, New York INFORMATION PREPARED FOR Additional Hard Copies Available From Microfiche Copies Available From Corporate Research & Development Distribution P.O. Box 43 Bldg. 5, Schenectady, N.Y. ,I2301 Technical Information Exchange P.O. Box 43 Bldg. 5, Schenectady , N.Y., 12301 TECHNICAL INFORMATION SERIES AUTHOR SUBJECT ~75CRDl19 Wentorf, ItH, Jr. hydrogen; energy DASEMay 1975 Hydrogen Generation HO PAGES 25 Power Systems Laboratory SCHESECTAGY. NY. ~ The main pses and methods of production of hydro- gen are discussed. Uses include ammonia and methanol syntheses, and hydrogenation or gasification of coal. Hydrogen will be too valuable to use simply as fuel unless fossil fuels become scarce (100-400 years). Hydrogen can be produced from water by using coal, natural gas, oil, or electricity. The primary energy source can be fossil fuels, nuclear, or solar. Closed cycle thermo- chemical processes are too inefficient and expensive to compete with coal based processes and probably also electrolysis. Hydrogen, methane, and other hydrocar- bons are relatively clean fuels, but to produce them on the scale presumably required in ten years will demand heavy use of coal. Large investments (hard work) will be needed and per capita energy use will probably decline as fuels become more costly. Technology cannot preservt the status quo. Coal is a dirty fuel, and protecting all forms of life during its heavy use will be expensive, but obviously necessary. hydrogen, energy, coal gasification, coal liquefaction, nuclear heat, energy transmission, energy storage, ammonia RD-54 tieixt PAGENO="0651" 645 HYDROGEN GENERATION R. H. Wentorf, Jr. INTRODUCTION Hydrogen is.a component of most fuels used today, particularly the more convenient liquid or gaseous fuels so easily obtained fron oil and gas deposits. Hydrogen is and will be too valuable to be used as a fuel as long as carbonaceous fuels are available. Arguments in this paper will show that the so-called "hydrogen economy", run on nuclear power, would be necessary only if no new energy technology were developed in the next 100 years or so while we use up our coal. In the meantime, hydrogen will be a key ingredient in many chemical processes, especially ammonia synthesis and its use will increase as coal products supplement dwindling oil and gas supplies. These changes in our energy sources will require both large investments (hard work) and a reduction in per capita energy consumption, but most people seem to be currently (March 1975) unaware of these coming changes and apparently hope that the technological establishment will somehow find ways to preserve the status quo. However, the technological discoveries necessary for this achievement are yet to be made and instead we must get along on natural resources of steadily declining quality while implementing the knowledge available today. A wise person bases his actions on certain knowledge, and if something unexpectedly good turns up, it will be easy enough to take. Personal energy consumption in the U.S. is over twice that in western Europe where comparable conditions of health and liesure prevail, and these two groups of people are considerably better off than most of the world. It almost appears that whether the U.S. "standard of living" will decline as a result of a moderate decline in energy usage as energy costs increase is to some extent a philosophical question of "What is good?" The answer depends upon a vigorous people's response to new conditions. Manuscript received 5/1/75. 1 PAGENO="0652" 646 The recent shortages of fuels and raw materials, coupled with inflationary practices, have made cost figures change so rapidly that they must often be dated by month and year and are soon obsolete. These trends will probably continue as fuels and materials become still scarcer and money is cheapened further. Accordingly, cost estimates used in this paper are usually relative, and where possible are based on a unit of energy, which represents a more stable basis of value. Some of these energy units are related as follows: 1 million Btu = 106 Btu = 252,000 kcal = 293 kw-hr ideal, (but only about 100 kw-hr when heat is turned into electricity in a modern power plant). Also, 1 million Btu is written as 1 MM Btu by fuel engineers,'and represents the combustion energy in about 1000 cu.ft. of methane or natural gas, or 80 lbs. of bituminous coal, or 7 gallons of gasoline or oil, or 3000 cu.ft. of hydrogen. Coal at $25 per ton is $1 per million Btu. A. Uses for Hydrogen In 1972 approximately 2700 billion standard cubic feet or 1.3 billion tons of hydrogen were produced in the U.S.A. This hydrogen was used as follows: ?~rnmonia synthesis 35% Hydrocracking of petroleum 30% Hydrotreating of hydrocarbons 21% Methanol synthesis 8% Other uses 6% 2 PAGENO="0653" 647 In the next ten years, hydrogen production for ammonia synthesis will probably increase at least two-fold as a greater need for food absorbs nore fertilizers. And additional hydrogen will be needed for the conversion of heavier prinary fuels, such as coal, to convenient liquid and gaseous fuels and other products. In the neantime, the hydrogen used in petroleum refining, which is largely generated inside the refinery by expelling hydrogen fron sone hydrocarbons, will be closely tied to petroleum consumption, which in turn is not independent of political developments. The main subject of this paper is the hydrogen which is not associated with petroleum. 1. Coal may be converted into methane as a substitute for dwindling supplies of natural gas by various processes now under active development. These processes differ in detail b~i generally make use of the following reactions among carbon, oxygen, and hydrogen: C + H20 = CO ÷ H2 (steam-carbon reaction,900°C) CO + H20 = CO2 + H2 (water-gas shift, 450°C) 2C ÷ 02 = 2C0 (partial oxidation, 800-1800°C) C + 2 H2 = CH4 (hydrogasification, 600-800°C) CO ÷ 3H2 = CH4 + H20 (methanation, 500-600°C) The first reaction is strongly heat-absorbing and some fuel must be burned to provide the heat for it. The fuel can be burned 3 PAGENO="0654" 648 completely to CO2 or it can be partly burned to CO, or it can be burned" in hydrogen to make CH4; all of these reactions liberate heat at temperatures high enough to help the steam-carbon reaction. But the water-gas shift and methanation reactions liberate heat at temperatures which are too low. The most efficient processes therefore make use of the hydrogasification reaction to supply heat for the steam-carbon reaction, so that the methanation reaction is used as little as possible. Even then the thermal efficiency of the process runs between 65 and 70%, and 30 to 35% of the heating value of the coal is lost (rejected to the local environment) in the process of upgrading the coal to the cleaner gas which can be distributed through existing pipelines. Most of the hydrogen required in the above process comes from water directly or indirectly, since coal is not very rich in hydrogen. A by-product of many of these processes is a mixture of unreacted carbon and ash known as coal char. 2. Coal may be converted to liquid fuels or hydrocarbon chemical feed stocks by two main techniques: Fischer-Tropsch synthesis, and hydrogenation-liquefaction. In the Fischer-Tropsch synthesis a-mixture of CO and H2 reacts at 300°C or less on certain metallic or oxide catalysts to form various paraffinic hydrocarbons. Methanol and other alcohols are also made from mixtures of CO and H2 under slightly different conditions. The CO and H2 may be prepared from coal at a thermal efficiency of about 65%. The reaction of CO with H2 liberates at moderate temperatures a fair amount of heat which was originally supplied at high temperatures for the steam-carbon reaction. Therefore the manufacture of fuels by the reactions of CO and H2 carries an energy and an available work penalty, and such processes will probably not compete with more efficient ones. For example, only about 45% of the original energy in the coal is found in the methanol made by this route. Methanol is a nice fuel in many ways, but it has only about half the combustion energy of gasoline per pound or per gallon, so that its transportation costs are higher. Mixtures of methanol and hydrocarbons (gasoline) 4 PAGENO="0655" 649 have been proposed as motor fuels, but they suffer from separation into two liquids when a little water is added. The Fischer- Tropsch process makes excellent Diesel fuels and poor gasolines, but, as with methanol, about half of the original energy of the coal is lost in the manufacturing process. 3. Instead of converting the coal to gas, one may convert it directly to a heavy oil by adding hydrogen to it. Sulfur is removed at the same time. Several processes are in the pilot plant stage; they are basically variations of work done in the 1920's by Bergius in Germany. In these processes pulverized coal is mixed with or even partly dissolved in a heavy oil or a hydrogen-donating solvent (tetralin, decalin). Some catalyst is often added; improvement in these catalysts is needed. In the presence of hydrogen at high pressures (100-300 atm) at about 400-450°C, the coal largely breaks down into oils. The reaction usually liberates a small amount of heat, but preparing the hydrogen in the first place requires heat. However, the overall yield of energy is about 80%, much greater than in the Fischer-Tropsch process. Hard coals resist liquefaction by this process; bituminous coals work well; so do sub-bituminous western U.S. coals, although their higher oxygen content increases the hydrogen requirement. Even so, not all the carbon in the coal is liquefied and the mixture of this residual carbon and ash is called coal char - it can be used to make hydrogen by reaction with steam. The heavy oil product has a low sulfur content and could be used as boiler fuel or upgraded to more valuable materials by processes requiring additional hydrogen. In addition to the heavy oil, lighter liquids and also gases such as ammonia, methane, and hydrogen sulfide are produced, depending on process conditions. 4. Pure hydrogen is probably the ultimate in clean fuels, but as gas it costs about 40% more per heat unit than synthetic methane and much more than natural carbonaceous fuels, and it is more difficult to store and handle. Liquid hydrogen is very cold, and to make the liquid adds about 30 percent to the cost of hydrogen. On the other hand, storage as 5 PAGENO="0656" 650 metal hydrides carries a severe weight and heat loss penalty as well as the problems of contamination by oxygen or water which combine with the metal and reduce its storage capacity. Methane has about 3 times the heating value of hydrogen per cubic foot, and so it is cheaper to transmit heating energy by pipeline as methane, not hydrogen. A system in which hydrogen serves as the principal fuel seems very unlikely as long as coal is available. Small percentages of hydrogen, generated by off-peak electrolysis of water, could be added to methane distributed for heating and cooking, but electrolytic hydrogen is currently the most expensive kind, and a good part of the off-peak electricity problem could be solved by law or changes in rate structure. Heavy, long-range aircraft night benefit from the use of liquid hydrogen as fuel because currently their fuel loads are major fractions of take-off weight. Hydrogen has a heat of combustion of about 26 kcal per gram vs. about 11 for kerosine, so that payload or range could be significantly increased. Suitable procedures for handling the cold, inflammable liquid would have to be worked out to ensure safety; considerable valuable experience has been obtained in the space program. 5. Hydrogen is being considered as a component of energy storage or transmission schemes. A simple method would electrolyze water to hydrogen and oxygen, which would be stored and used later in a fuel cell or turbine-generator. This procedure is not very efficient at current levels of technology because, at reasonable outputs, fuel cells now deliver only about 0.8 volt of the theoretical 1.23 for an efficiency of 65%, and gas turbine cycles can yield at most 45%. The electrolysis of water at reasonable rates proceeds at 2 to 2.2 volts, corresponding to efficiencies of 60-65%, so the overall storage and recovery efficiency would be only about 35-40%, from electricity in to electricity out, and only about 10% from coal in to electricity out. Improvements in electrolysis, fuel cells, and gas storage are needed before this scheme would be worthwhile on an energy basis. 6 PAGENO="0657" 651 A more attractive storage scheme uses a mixture of Co and H2 and is based on the reactions:. CO + 3H2 = CH4 + H20 2C0 + 2H2 = CH4 + CO2 At high temperatures (800-900°C) and low pressures, the reactions proceed to the left with absorption of about 55 kcal per nol of CH4; at high pressures (50 atm) and somewhat lower temperatures (400-600°C) the reactions proceed to the right and liberate about 55 kcal per mol of CH4. The gases do not react at room temperature, only when hot and in the presence of a catalyst, usually nickel. Thus, energy can be stored or transported as a cold, gaseous mixture of CO and H2, to be used when and where needed. A 100 mile pipeline of slightly larger than average diameter can store enough gas to smooth out peaks and valleys in daily demand; longer storage times can be achieved with under- ground reservoirs. The reacted gases containing CH4 can be stored or returned for another heat absorption cycle. Similar schemes employing hydrogen and cyclic ring compounds such as toluene or naphthalene are proposed for use at lower temperatures around 300°C. Here the addition of hydrogen liberates heat and de- hydrogenation absorbs heat. These schemes could be used with various heat sources such as nuclear reactors or high temperature solar collectors and are well-suited to delivering a mixture of heat and electric power to heavy usage areas such as cities. B. Generation of Hydrogen 1. By reactions with carbonaceous fuels. Most hydrogen is currently made from methane (natural gas) by steam-reforming at about 900°C: CH4 + H2O 3H2 + CO This reaction absorbs considerable heat, 55 kcal per mol of CO, which is furnished by a gas-air flame on the outside of the reformer tubes. Next the CO is shifted to form more H2 by 7 62.332 0 - 76 . 42 PAGENO="0658" 652 reaction with steam at about 400°C: Co + H20 = H2 + CO2. Finally, the CO2 is stripped out and thrown away. In ammonia synthesis CO is bad for the catalyst and must be renoved. The methanol catalysts are sensitive to sulfur. Hydrogen prepared from natural gas costs about as much per cubic foot as the gas fed; half the cost is for plant, labor, etc., and the other half is for the gas supplied. Hydrogen can also be prepared by the partial oxidation and reaction with steam of naphtha or heavy fuel oils. The plant costs about twice as much as when methane is the feed, primarily due to the need to supply high purity oxygen from an air separation plant, and the hydrogen produced thus costs about 50% more than when it is made from methane. However, it is an economical process where natural gas is dear and heavy oil is cheap and ammonia is needed. In both the above processes, the heating value of the hydrogen produced is about 65% of the heating value in the hydrocarbon feed, and 35% is used for generating power or escapes to the atmosphere. An important source of hydrogen in a petroleum refinery is the formation of aromatic compounds such as toluene, xylenes, etc. from naphthas, which proceeds at moderate temperatures (250°C) over platinum catalysts, for example: C8H16 = C8H10 + 3H2 The aromatic products are more valuable as motor fuels or chemical feedstocks than the original naphthas, and the hydrogen is used elsewhere in the refinery for desulferization, hydrocracking, hydrotreating, and other operations requiring the presence of hydrogen. When coke is made from coal, the coke oven gas may contain up to 50% hydrogen, along with methane, ammonia, hydrogen sulfide, etc., and it is often practical to purify this gas and use it 8 PAGENO="0659" 653 for ammonia synthesis. Coal or coal char can be used to make hydrogen by the steam-carbon reaction, which runs at 800-1000°C and absorbs'much heat, about 30 kcal per mol of CO: C+ H20 = CO 4- The CO can then react with more steam over nickel or iron- chromium oxide catalysts a% about 350°C to liberate a little heat (10 kcal) and make hydrogen and carbon dioxide: CO + H20 = H2 + CO The CO2 is then stripped out using alkali or amines, etc. which can be regenerated (It is a pity that the CO2 can't be given directly at high concentrations to green plants so as to aid their growth rates). Coal char is the carbonaceous residue left from the manufacture of methane or liquid fuels from coal; it consists mainly of carbon and mineral matter. The basic reactions described above can be carried out in several ways. In one method, coal is burned with oxygen and steam, and the heat needed for hydrogen formation is supplied directly by burning carbon. This method requires an oxygen plant which adds to the capital cost. (The cheapest way now known to produce oxygen is by the distallation of liquid air). With coal at $l2-l4 per ton, the hydrogen produced by such a plant costs about $2-3 per million Btu or $0.65-0.95 per thousand cubic feet (1974). The sulfur in the coal appears as H2S which can be stripped out and converted to sulfu± by well-known processes. One notes that if half our current petroleum consumption of about 16 million barrels of oil a day were provided by lique- faction of coal containing 3% sulfur which was removed, and the processes used had thermal efficiencies of 75%, the coal requirement would be 3.3 million tons per day or 1,200 million tons per year, and the sulfur produced would be about 36 million tons per year. These rates are each approximately twice the U.S. current production of co&l and sulfur. Evidently sulfur 9 PAGENO="0660" 654 will be in great surplus. The sulfur originally appears in the gas as hydrogen sulfide, H2S, and current practice for converting it to a fairly inert, low-polluting form, namely elemental sulfur, is the. Claus process, which in effect burns off the hydrogen, using the two steps: H2S + l~- 02 = H20 + SOB' 502 ÷ .H2S = 2H20 + 3S Somehow it seems a shame to lose the hydrogen won at such expense. Experiments are being conducted on methods for undergound gasification of coal. The idea is to partially burn the coal, ~usually in the presence of steam, to make useful gas without digging up the coal. Presumably the coal in a seam would be fractured enough to allow gases to pass through it, from inlet wells carrying oxygen (or air), and steam, through a hot reaction zone, and out another set of wells or pipes as product gas. The problems are to control the reaction of the coal in a bed of erratic sh~pe, where blocking of the gas stream can occur by ash, or hot, plastic coal. Or short-circuit channels might form which would permit the wasteful combustion of gaseous products with incoming oxygen. Finally, the rock roof may fall in and shut everything off as well as create a minor local earthquake or subsidence on the surface above the mine. Considerable testing will be required to find out if underground coal gasification ~5 practical, and techniques for drilling wells will also have to be improved. If successful, the method would save considerable life, injury, and expense compared with digging coal out of deep mines, where most of our coal lies. In another method for producing hydrogen called the steam- iron process, no oxygen plant is required. Steam is passed through a hot (900°C) bed of mainly ferrous oxide, FeO, whereby hydrogen and magnetite iron oxide are formed and about 17 kcal per mole of H2 is liberated: 10 PAGENO="0661" 655 3FeO + H20 = Fe304 ÷ H2. The hydrogen is easily separated by condensing the steam. After the FeO has been pretty well oxidized, the steam is switched off and CO, made by burning carbon (coal, char) in a limited air supply, is passed through the hot bed, whereupon the magnetite is reduced back to FeO and perhaps some iron: Fe304 + Co + N2 = 3FeO + CO2 + N2 About 7 kcal per mol of CO is absorbed in this reaction, but of course burning the carbon to make CO liberated heat, more than enough for this reaction as well as to make steam for the first reaction. Presumably the extra heat cou~ld be used to generate steam for electricity. In practice the reactions are not complete and some CO is lost. While the bed is being switched from one gas to another, some mixing of gases may also occur. At the high temperatures prevailing in the bed, 800-1000°C, the bed particles tend to sinter together so 4hat the total surface area declines and the bed is less effective. The sulfur from the fuel burned to make CO must be removed, either as H2S before reaction with magnetite, or as SO2 later from the hydrogen. Another process, still in the laboratory stage, which does not require an oxygen plant, makes use of the mobility of oxygen as oxide ions at high temperature~ in certain ceramic materials, particularly those based on zirconia. In this scheme the special ceramic at 800-1000 °C lies between steam on one side and a reducing atmosphere containing CO on the other. Thus there exists a chemical driving force favoring the migration of oxygen from the steam through the ceramic to the CO side, where it forms C02: H2O~H2+ (0) (0) + CO CO2 The hydrogen is easily separated from the steam and is naturally quite pure since the ceramic transmits only oxygen and electrons. 11 PAGENO="0662" 656 Some heat, about 10 kcal per mol of CO, is liberated in the process. The burning of carbon supplies CO and heat for making steam. The ceramic is made electrically conducting by adding certain other oxides to it so that electrons may flow to counter- balance the electric field produced by the motion of the oxide ions, and no special electrodes may be necessary. The sulfur in the fuel must be removed either before oxidizing the CO, or if the ceramic is tolerant of sulfur, as sulfur dioxide in the stack gases. Finally, nuclear heat from a high temperature reactor might be used to supply the heat for making hydrogen. This could be done directly, by heating the coal, coke, char, etc., in a bed to about 800-900°C using hot helium from the reactor flowing inside heat exchange tubes in the bed, and passing steam through the bed for the steam-carbon reaction. Or it could be done indirectly, using methan~ as an intermediate, as follows: Nuclear heat (hot helium) surrounds tubes filled with catalyst in which methane is steam-reformed to CO and hydrogen, thereby absorbing much heat: CH4 + H2O = CO + 3H2 Part of this hydrogen is then passes into a bed of hot coal where the hydrogasification reaction occurs: C + 2H2 = CH4 This reaction liberates about 20 kcal per mol of CH4, more than enough to keep the bed hot. Extra H2 and CO are left over and can be used for other purposes. The CH4 is purified from other materials, particularly sulfur compounds produced by the action of hydrogen on coal, and mixed with steam for another hydrogen-making pass. Many parts of this process are in the pilot-plant stage. In most of the processes involving coal and hydrogen one is faced with severe materials problems due to the high temperatures, abrasive materials, and presence of sulfur. Economical solutions to these problems have not all been worked out. Also not developed are the mining and transportation facilities for large amounts 12 PAGENO="0663" 657 of coal. 2. Electrolysis of Water. Usually hydrogen made by electrolysis of water is quite expensiva and is reserved for uses requiring high purity, such as hydrogenation of edible oils or sensitive metallurgical processes. At room temperature, 1.23 volts is theoretically required to decompose water to hydrogen and oxygen at one atmosphere pressure. As the temperature increases, the required voltage falls, so that at 927°C, a temperature suitable for ceramics and superheated steam, the required voltage is about 0.94 volt. However, the theoretical voltages are greatly exceeded in most practical process for two nain reasons: (a) Resistive voltage drop in the electrical conductor and the electrolyte and (b) chemical kinetic factors at the electrodes which limit the rate of gas production, particularly at the oxygen electrode where a peroxide intermediate seems to be involved at temperatures up to at least 130°C. Three main techniques could be considered for water electrolysis, according to the temperature range, and electrolyte used: (a) At temperatures up to about 100°C, the electrolyte is usually strong caustic such as a 25% NaOH or KOH solution and the electrodes are mostly rather inexpensive metals such as iron and nickel. The cells are usually run at pressures greater than atmospheric in order to reduce the anount of water vapor carried off in the gases, to decrease the size of the bubbles and thereby reduce the resistance between electrodes, and to minimize work of compressing the gases, since the extra voltage required for pressures of a few tens of atmospheres is negligible. If you are in a hurry and donTt want to spend much on equipment, you may end up applying 2.2 volts per cell. More expensive equipment with special electrodes running at slower rates can 13 PAGENO="0664" 658 bring the voltage per cell down to 1.8 or so. Theoretically, the heat of combustion of hydrogen to water exceeds the work of electrolysis (68 kcal vs. 57) 50 that the electrolysis cell should act as a refrigerator. In practice, the various power losses swamp this difference, and the cell acts as a heater. about 26-27 kw-hr are needed to produce 1 pound (about 180 cn.ft.) of hyrdrogen by these methods today, for a thermal efficiency of about 63%. Moving up in temperature to 110-120°C, one nay use solid polymer electrolyte cells. Here gas bubbles do not add electical resistance because a special polymer is used as the electrolyte. A thin layer of the polymer carries hydrogen ions from hot, pressurized water at one electrode (thereby liberating the oxygen of the water as gas) and deposits these ions at the other electrode where they form hydrogen gas. The cell ~`o1taqes are lower by this method than when caustic water electrolytes are used, and range between 1.45 volts at 50 amps per ft2 to 2.05 volts at 1600 amps per ft2. These cells are the most efficient available today and require about 20 kw-hr per pound of hydrogen for an efficiency of over 80%. Further improvement is possible by using thinner polymer layers, higher temperatures, and more active electrodes. At still higher temperatures, of the order of 800-1000°C, ceramic electrolytes based on zirconia, etc., might be used to carry oxygen away from steam as oxide ions. Here the resistive losses in the ceramic become a major factor affecting efficiency, since the over-voltages associated ~ith chemical kinetics are minor at high temperatures. Furthermore, the theoretical voltage is lower and a larger fraction of the energy for splitting water is supplied as heat. The main problems in the way of this attractive solution are to find economical long-lived electrode materials and electrical lead wires for cells operating at these temperatures. 14 PAGENO="0665" 659 The energy yield of hydrogen per unit of fuel burned is limited by the efficiency of turning heat into electricity; this reaches about 40% in the best nodern plants; the other 60% is dumped to the atmosphere. A reasonable expectation is for an electrolysis efficiency of 85% so that the overall yield could rise to about 35%. Only very cheap non-fossil fuel power could be used to make hydrogen on a large scale by electrolysis as long as coal or other hydrocarbons are plentiful, since coal could be used more effectively to make hydrogen by the reaction of carbon with steam than b~ burning the coal to make electricity for electrolysis. 3. Closed Cycle Thermochemical Water Splitting. Over the past decade, and more frequently in the past few years, schemes have been proposed for splitting water by combinations of chemical reactions operating at different temperatures, so that water and heat are fed into the process and hydrogen, oxygen, and waste heat leave the process. Water does not appreciably decompose by pure heat alone until temp- eratures of the order of 2500°C are reached. For at least the next 10 years, materials of construction limit nuclear reactor output temperatures to about 1000°C in helium at 40 atmospheres. (Higher temperatures are of course achieved by burning carbonaceous fuels, but this process is closed only by the photosynthetic activities of green plants). Thus one may consider processes of the general type: A + H20 = AO + H2 at temperature T1 AO + B = AB + ~O2 at temperature T2 AB = A + B at temperature T3 sum: H2O = H2 + where A, B (and perhaps C, D, E, etc. added too, depending on the complexity of the process) are chemical species to be selected out of the thousands known. 15 PAGENO="0666" 660 Instead of applying electric work, as in electrolysis, to split water, we now propose to apply only heat. In any case the total heat of formation of water, 68 kcal per mol, must be supplied. Since the chemical plant is in effect an engine for splitting water,the Carnot limitation on efficiency applies for the process, so that if and kcal of heat are taken in at absolute temperatures T1 and T3 and rej~cted at T0, the maximum work available from this heat, namely Q1 (l-T0/T1) + Q3(~T01"T3) must equal or exceed the theoretical work required to split water, about 56 kcal per mol. Clearly, the larger T1 and T3, the less heat is required, but we are limited in practice to about 1200°K. After heat exchange with the 1000°C helium, which is thereby cooled to say 700°C, one could take the average maximum temperature CT1 or T3 above) in any such process to be about 827°C or 1l00°K. Heat can be rejected at about room temperature, 300°K. Thus, we have Q(l-300/llOO) = W, the work to split water. Or W/Q0.73 is the maximum theoretical work efficiency if all the heat for theprocess is taken in at the maximum practical temperature and there are no losses. In practice, there are bound to be losses, and we might strive for the same relative losses as are experienced in the best steam power generating plants and finally hope to achieve 70% of the maximum theoretical efficiency, even though in the chemical plant we are doing a lot more than simply circulating hot water. Thus it would be realistic to expect over- all cheniical cycle efficiencies of at most about 50% (0.73 x 0.70). On account of the large quantities of hydrogen involved, the cycling species, A, B, C, etc., must be relatively cheap or their inventory would constitute an intolerable expense. They should also be relatively non-toxic. Therefore chemical cycles involving metals such as iron, magnesium, copper, nickel, and non-metals such as sulfur, chlorine, carbon, etc., have been proposed, along with more exotic species. Some of the proposed cycles actually work, but often they contain steps in which 16 PAGENO="0667" 661 the equilibrium concentration of the desired product is small. Cycles involving about 4 to 8 steps are usually thought to be most suitable. In most of these cycles one sooner or later has to deal with corrosive materials at high temperatures, since after all, water is necessarily involved in the process, and this fact, coupled with the necessity for heat exchange at high temperatures, plus the large number of chemical steps actually involved, means that the plant must be relatively large, roughly 3 times that of a steel plant handling the same amount of energy as coal and iron ore instead of hydrogen. (Both plants would handle about twice as many Btu'S as they produce in oxidizable material, but the steel plant does not need to recycle ash, slag, etc., and its heat transfer processes are more direct). In order to improve efficiency, the investment must increase: for example, a lower temperature drop across a heat exchanger means a larger exchanger. Nuclear energy all by itself as uranium is relatively cheap, but one cannot burn nuclear fuel in just any furnace, as one can do with coal or oil, and so controlled, delivered nuclear heat costs at least 30% more than the heat from burning coal. A 50% conversion efficiency of nuclear energy into hydrogen energy, which one may take as a realistic maximum after considerable development, means that the hydrogen energy must cost at least twice the nuclear energy used to make it, even if the chemical plant costs nothing. But it is evident that the plant will reruire a large investment on account of the large number of chemical steps and corrosive conditions involved. In the mean- time, hydrogen can be made from coal or the even cheaper char at an energy cost of a little less than twice the cost of this cheaper fuel, and the plant investment is much less (With coal, the fuel and the substance which reacts with water are one and the same; it is hard to beat this combination). 17 PAGENO="0668" 662 Thus one concludes that thermochemical hydrogen will not be worthy of consideration until carbonaceous fuels are quite scarce and expensive, and the main competitor for therrno- chemical hydrogen will be electrolytic hydrogen. Favoring electrolytic hydrogen are the relatively low plant costs and the thermodynamic simplicity and advantages of absorbing heat by a relatively inert working fluid over the entire range of reactor output temperature instead of just in the specific intervals required by particular chemical reactions. The thermo- chemical system nay offer a higher efficiency, but at considerable cost in both dollars and energy, and further developments in electrolysis techniques, particularly at higher temperatures, will narrow this efficiency advantage in the future. For the above basic reasons, without going into the details of the dozens of specific chemical prOcesses which have been proposed, one can conclude that thermochemical hydrogen, while an interesting technical exercise, is unlikely to be a competitive process for at least the next 100 years. So far no one has found a good way to couple the energy of the fragments of fissioning uranium atoms to the direct decomposition of water. A nuclear reactor does make a certain amount of hydrogen from water in this way, but the amounts are miniscule. 4. Solar and Biological Hydrogen Generation. In effect, all hydrogen made from carbonaceous fuels is derived from the solar energy trapped in ancient p1ant~ and animals at a slow rate and now burned up at a rapid rate by humans. Although the solar input to the U.S.A. is about 500 times its current fuel consumption (at 1% efficiency, we could meet all our energy needs by the sunlight falling on 20% of our land) the sunlight is a relatively dilute source which some consider ill matched to the intensive needs of modern, high speed industrial civilization. 18 PAGENO="0669" 663 Four ways are open to make hydrogen using solar energy: (a) Concentrating sunshine so as to drive a heat engine which makes electricity for electrolysis of water. (b) Absorbing sunlight in special materials such as silicon, titania, etc., which produce an electric current which can be used for electrolysis of water. (c) Allowing sunlight to make photochemical changes in certain materials, the net effect of which is to decompose water into hydrogen and oxygen. (d) Usi~ng green plants and their companion bacteria to make sugar, starch, cellulose, amino acids, methane, etc., harvesting these materials, and converting them to other necessary materials. In this last method of operation, hydrogen is not needed on a large scale because many of the things for which hydrogen might be required are already produced by green plants, e.g., food, fiber, fuel, and construction materials - the method has worked well for thousands of years and probably can be improved in particular respects as our understanding grows, especially in regard to bacteria, which are quite adaptable organisms. Method (a) ~is relatively straight-forward as far as hydrogen goes and need not be discussed further here. Method (b) is particularly interesting when the light falls on an electrode in an aqueous solution. The best known example of this effect is furnished by a titanium dioxide (rutile) electrode, which generates oxygen plus an electric current which can be used to produce hydrogen at another electrode, when the rutile electrode is illuminated by blue or ultra- violet light. Unfortunately sunlight falling on the earth's surface contains only about 8% of this kind of light and the overall yield of hydrogen and oxygen per unit area lit is very low. Large areas would be needed for significant amounts of 19 PAGENO="0670" 664 gas. Possibly other electrode systems can be found which will be cheaper, and more efficient in their use of the red, yellow and green parts of sunlight. Method (c) is nearly entirely speculative at this stage, since the only photochemical reactions known either require ultraviolet light or proceed at very low efficiencies using expensive materials. The method could be considered part of the larger problem of storing and concentrating the energy of sunlight as chemical energy in some form, not necessarily hydrogen and oxygen from water. If such methods could be found which used inexpensive materials at 10-20% sunlight efficiendy, mankind's long-range energy problems would be simplified, provided population was kept within bounds. In other words, we could live on our solar income and would not need to consume our capital of oil and coal (We could live on our current income of sun, water, and wind energy plus vegetable matter if current populations were smaller, but human population may already be too large to be supported in this way, even at reduced demand for energy). c. Environmental Effects of Hydrogen Production and Use Pure hydrogen is a clean fuel; the main problem in burning it in air is the production of nitric oxides at high temperatures. But pure hydrogen is really too expensive to be considered as fuel for at least the next 100 years. Of greater immediate concern are the environmental effects associated with the heavy use of coal or nuclear power used to make hydrogen and other fuels by the methods mentioned. Coal is basically a dirty fuel and all forms of life must be protected during its use. Air, water, and land are all affected. Naturally, the greater the efficiency of the coal-refining process, the less coal is used to meet our needs and the less the contamination of the environment. 20 PAGENO="0671" 665 1. Air is contaminated and heated. Contaminants are sulfur compounds (SO2, H2S, H2S04), nitrogen conpounds (ammonia, various anines, nitric oxides), hydrocarbons (some of which are carcinogenic), carbon monoxide, carbon dioxide (which has many potential uses, e.g., aiding plant growth), volatile compounds of harmful elements (such as lead, cadmium, arsenic, mercury, uranium), dusts containing these elements, rock dust associated with raw coal, coal dust (Black Lung), and smoke and soot. All these air contaminants can be controlled within acceptable limits, but extra expense and vigilance are required, especially when coal is used on a large scale. Perhaps a simple solution is to require that the environmental control manager of the plant live within one mile, downwind. The heating of the air is inevitable even if cooling water is used, since warm water quickly evaporates and loses its heat to the air. Another air contaminant which receives too little attention is noise. Noise is often reflected or refracted by temperature inversion layers in the atmosphere to make life unpleasant for people living 3 to 10 miles from the source. The enormous amounts of coal required for even a moderate sized plant, 25,000 tons per day, imply many carloads or boatloads of coal per day, and efforts should be made to reduce the clanking, rumbling and howling involved in handling this coal. After all, the whole idea of going to all this trouble about fuels is to make life better. The use of solar energy to meet part of our energy needs would have only minor effects on climate and weather since the amount of energy extracted from sunshine would be less than 2% of the amount which falls on any reasonably large area (20 by 20 miles) and would be given up again as heat after use. 2. Water is also contaminated. Large amounts of water are needed to wash raw coal, and considerable mud, etc., accumulates, much of which contains oxidizable sulfur which 21 PAGENO="0672" 666 makes sulfuric acid. Large storage areas will be needed for this material so that contaminants will not run off. into streams and rivers before the solid material can be returned to worked out nines. Naturally wash water and cooling water should be recirculated as much as possible. Cooling water nay collect undesirable species such as axnmonia, sulfur compounds, cyanides, phenols, hydrocarbons, etc. Existing pollution standards, if followed, would prevent stream and river contamination by such water. It may be environmentally desirable to feed such water into the hydrogen manufacturing steps. A good use for most of the ammonia and part of the sulfur produced would be as arnmonium sulfate fertilizer. However, as remarked earlier, sulfur extracted from coal could soon nearly fill our other needs for sulfur, and when coal was our main source of energy, sulfur would need to be returned to the mines or stored for the use of future generations after the coal is gone. 3. Land should be respected as the source of food and pleasure and not irreversibly torn up and destroyed for a temporary shot of energy. Strip miming operations should be required to restore the land to its original condition or better in return for the coal dug from it. Considerable care may be required to ensure proper drainage patterns. Atmospheric and water pollutants from freshly mined coal and rock must not be allowed to affect agriculture or wildlife. The diversity of living forms should be preserved to maintain a sufficiently large gene pool for new breeding stocks to resist pests and diseases. It is not merely a question of aesthetics. 22 PAGENO="0673" 667 REFERENCES Hydrogen is so intimately connected with most forms of energy supplies and use that references on the subject can go on indefinitely. Some of the information in this report is based on conferences or papers not yet in print, or not widely available, or the result of private thought and discussions. But the interested reader may find the following references helpful: Coal: 1. "Synthetic Fuels from Coal", Project Independence Blueprint, Final Task Force Report, U.S. Department of the Interior, November 1974. 2. "Coal" in Kirk-Othmer "Encyclopedia of Chemical Technology", 2nd revised edition, Wiley Interscience, New York (1968). See also "Gas, Manufactured", and "Carbon monoxide-hydrogen reactions". 3. "An Economic Study of Pipeline Gas Production from Coal", by a. P. Henry, Jr. and B. M. Louks, Chemical Technology, April 1971, pp 238-247. 4. "Coal Gasification System", by J. F. Farnsworth, H. F. Leonard, and D. M. Mitsak, 33 Magazine/The Magazine of Metal Producing, August 1973. 5. "Desulft~rization of Coal", by A. Saleem, Ontario Hydro Research, Quarterly Bulletin, V. 23, No. 2, Second Quarter (1971). 6. "Low-sulfur Fuel Oil From Coal", by S. Akhtar, S. Friedman and P. M. Yavorsky, U.S. Bureau of Mines Coal Desulfurization Program Technical Progress Report 35, July 1971, Pittsburgh, PA. Electrolysis: 1. "Water Electrolysis" in "Encyclopedia of Electro-Chemistry" Reinhold, NY (1964). 2. Chemical Engineering News, vol. 46, p. 48, November 1968. 3. "Electrochemistry of Cleaner Environments", ed. by J.O'M. Bockris, Plenum, NY (1972). 4. "Electrochemical Dissociation of Water Vapor in Solid Oxide Electrolytic Cells", by H. S. Spacil and C. S. Tednion, Jr., Journal Electrochemical Soc., vol. 116, pp 1618-1626 (1969). 5. For most recent developments, see pp S9-l to S9-40 in Conference Proceedings)The Hydrogen Economy Miami Energy (THEME) Conference, 18-20 March 1974, edited by T. N. Veziroglit, University of Miami, Coral Gables, Florida, 33124. 23 62-332 0 - 76 - 43 PAGENO="0674" 668 Energy and Ecology: 1. Science, vol. 184, April 1974 (entire issue). 2. "Small is Beautiful", by E. R. Schumacher, Harper and Row, New York (1973). 3. "Energy: The Squeeze Begins", by J. H. Krieger, Chemical and Engineering News, November 13 (1972), pp 20-37. 4. Ninth Intersociety Energy Conversion Engineering Conference, 1974 Proceedings, lua. Soc. Mech. Engrs., New York (1974) 5. "The Energy Index 74", published by Environment Information Center, Inc., Energy Reference Department, 124 E. 39th St., New York, NY 10016 (December 1974). Food: 1. "Food Production and the Energy Crisis", by David Pimentel et al, Science, vol. 182, pp 443-449 (1973). Hydrogen: 1. "Selected Topics on Hydrogen Fuel", by W. R. Parrish, R. D. Voth, J. G. Hust, T. M. Flynn, C. F. Sindt, N. A. Olien and J. Hord, NBSIR 75-803, Cryogenics Division, National Bureau of Standards, Boulder, Colorado 80302, January 1975. 2. "A Hydrogenergy Carrier", vol. II, Systems Analysis, 1973, NASA-ASEE. NASA Grant NGT 44-005-114. Editors R. L. Savage, et al, September 1973. 3. "Hydrogen in Kirk-Othmer Encyclopedia of Chemical Technology" Wiley-Interscience (1968). See Also "~unmonia" and "Methanol". 4. "Thermochemical Hydrogen Generation" by R. H. Wentorf, Jr. and R. E. Hanneman, Science, vol. 185, pp 311-319 (1974). 5. Conference Proceedings, "The Hydrogen Economy Miarii Energy (THEME) Conference, 18-20 March 1974. Ed. by T. N. Veziroglu, University of Miami, Coral Gables, Florida. 6. "The Hydrogenation of Organic Compounds", by C. Ellis, Van Nostrand, NY (1931). 24 PAGENO="0675" 669 Nuclear Reactors, High Temperature: 1. `The Pebble Bed High Temperature Reactor as a Source of Nuclear Process Heat", vol. 1-7, by R. Schulten, K. Kugeler, M. Kugeler, H. Niessen, H. Hohn, 0. Woike and J. H. Germer, Kernforschungsanlage Julich, W. Germany (1974). 2. Pages S3-l to S3-49 of "The Hydrogen Economy Miami Energy (THEME) Conference, 18-20 March 1974. Edited by T. N. Veziroglu, University of Miami, Coral Gables, Florida. 3. British Nuclear Energy Society International Conference, "The High Temperature Reactor and Process Applications" London, 26-28 November 1974. Published by Thomas Telford, Ltd., Institution of Civil Engineers, 26-34 Old Street, London EC1V 9AD. Photosynthetic Solar Energy: 1. "Solar Energy by Photosynthesis" by Melvin Calvin, Science, 184, pp 375-381, (1974). 2. "Electrochemical Photolysis of Water at a Semiconductor Electrode" by Akira Fujishima and Kenichi Honda, Nature, vol. 238, p. 37 (1972). 3. "Electrochemical Aspects of Solar Energy Conversion", by Nary D. Archer, The Royal Institution, 21 Albemarle St., London WIX 4B8, August 1974. 4. "The Current State of Knowledge of Photochemical Formation of Fuel", ed. by N. 0. Lichtin, Boston University, September 1974. 25 PAGENO="0676" PAGENO="0677" 671 APPENDIX II ADDITIONAL MATERIAL FOR THE RECORD PAGENO="0678" 672 PAGENO="0679" 673 Hydrogen as a Navy Fuel A Study Paper Prepared by the NRL Hydrogen Panel NRL Report 7754 HOMER W. CARHART, Chairman WILBUR A. AFFENS, BRUCE D. Boss, ROBERT N. HAZLETT AND SIGMUND SCHULDINER June 12, 1974 NAVAL RESEARCH LABORATORY Washington, D.C. Approved for public release; distribution unlimited. PAGENO="0680" 674 SECURITY CLASSIFICATION OF THIS PAGE (IThoc Dots Ectocod) 0E0~T rNflE'IIUC ITATIrIkI DAI'E READ INSTRUCTIONS BEFORE COMPLETING FORM I. REPORT NUMBER 2. GOVT ACCESSION NO. NRL Report 7754 3. RECIPIENT'SCATALOG NUMBER 4. TITLE (ocd S,,btIfIc) HYDROGEN AS A NAVY FUEL S. TYPE OF REPORT & PERIOD COVERED Special study 6. PERFORMING ORG. REPORT NUMBER 7. AUTHOR(s) H.W. Carhart, W.A. Affens, B.D. Boss, R.N. Hazlett, and S. Schuldiner 4. CONTRACT OR GRANT NUMBER(S) o. PERFORMING ORGANIZATION NAME AND ADDRESS Naval Research Laboratory Washington, D. C. 20375 10. PROGRAM ELEMENT. PROJECT, TASK AREA & WORK UNIT NUMBERS II. CONTROLLING OFFICE NAME AND ADDRESS 12. REPORT DATE June 12, 1974 13. NUMBEROFPAGES 38 14. MONITORING AGENCY NAME & ADDRESS(I1 dill soot,, foot,, Co,,tooIlicg Ohio.) 15. SECURITY CLASS. (of this roptot) Unclassified ISo. DECLASSI FICAT1ON/ DOWNGRADING SCHEDULE 6. DISTRIBUTION STATEMENT (of thlo Ropoot) Approved for public release; distribution unlimited. 17. DISTRIBUTION STATEMENT (of tho sb.tosot ottt.rsd I,, Block 20, if diff.oottl boo, R.pot't) 18. SUPPLEMENTARY NOTES 19. KEY WORDS (ccothtoo ott sssids if ooc..ssoy ~id idontify by block nco,b.o) Flammability hazards Hydrogen usage Hydrogen Navy fuel Hydrogen production Hydrogen storage 20. ABSTRACT (ContIncn on tocooso old. if onc...aty and idontify by block rn,o,b.r) Hydrogen has desirable properties as a fuel. It can be burned in all burners and engines in widespread use today and is a superior material for fuel cells. A high heat of combustion makes hydrogen attractive, but its low density negates much of the advantage obtained by the heat of co.iibustion, particularly for volume-limited vehicles. Thus, the use of hydrogen in major ships and carrier aircraft is not promising. Hydrogen is not a prime fuel; it is produced by putting energy into chemical reactions. Hazards with gaseous hydrogen are greater than with most com- bustible gases, but suitable handling techniques are available. Experience with liquid hydrogen DD JAN73 1473 EDITION OF 1 NOV 65 IS OBSOLETE S/N 0102'014' 6601 I SECURITY CLASSIFICATION OF THIS PAGE (W9t.n Data Zntot.d) PAGENO="0681" 675 LLtJ~OTy CLASSIFICATION OF THIS PASE(Wh~,, D&~ E~t~~.d) is limited, however, and explosion hazards must be examined. The increase in crude oil prices coupled with the decreasing oil reserves-to-production ratio indicates that hydrogen will not be at as large an economic disadvantage as it is today. The cost of hydrogen should not be a deter- rent to its use in the Navy if system performance shows significant advantages. 11 SECURITY CLASSIFICATION OF THIS PAGE(Wh.n Data £at.r.d) PAGENO="0682" 676 CONTENTS INTRODUCTION 1 PROPERTIES OF HYDROGEN AS A FUEL 3 Chemical Oxidation Electrochemical Oxidation 6 HYDROGEN PRODUCTION 12 Fossil Fuels 13 Nonfossil Fuels 14 Electrolysis 14 Thermal Energy 15 Production-Cost Summary 16 Commentary HYDROGEN STORAGE 18 StorageasaGas 18 Storage as a Liquid 19 Unconventional Storage Methods 20 H2 Liquefaction Energetics 20 LIQUID HYDROGEN USAGE IN THE NAVY 20 Comparison of LH2 and Petroleum Fuels for Today's Fleet 20 Usage in Fleet After Year 2000 21 Other Factors 23 Other Concepts 23 Special Applications 23 HAZARDS IN THE STORAGE, TRANSPORTATION, HANDLING, AND USE OF LIQUID AND GASEOUS HYDROGEN 24 History 24 Nature of the Hazard of Hydrogen 25 TOXICITY AND EFFECT ON THE ENVIRONMENT 29 Engine Exhaust 29 Thermal Pollution 29 Toxicity 29 111 PAGENO="0683" 677 CONTENTS-Continued CONCLUSIONS 29 REFERENCES 30 iv PAGENO="0684" 678 HYDROGEN AS A NAVY FUEL INTRODUCTION Hydrogen (H2) is one of several fuels available for the long term. It offers a means of energy storage, particularly when environmental sources (sun, wind, tides, geothermal and ocean thermal gradients, ocean currents, etc.) are tapped, since these energy sources are restricted geographically and may be intermittent. Hydrogen is not a source fuel, however, and must be produced from energy from some other source. It can be produced and used either chemically or electrochemically and is also the ideal nonpolluting fuel. Its potential use on a large scale by the Navy will of necessity be tied closely to its general application in the civilian economy. Enormous quantities of hydrogen would be required to replace completely fossil fuels. For the years 1975 and 2000, the projected electrical demand needed to produce the re- quired H2 by electrolysis of water would amount to 14 to 15 trillion kWh at a rate of 1.7 to 5.1 million MW. Since the projected production of U.S. production of electrical energy for those years is 1.96 trillion and 10.9 trillion kWh, full conversion to electrically produced H2 by 2000 is unrealistic even from the most optimistic viewpoint. A major problem with hydrogen is storage. A cylinder containing 1 lb of H2 at 2000 psi weighs about 125 lb. A cylinder contalning H2 would produce 51,600 Btu. Thus, about 40 cylinders would be equivalent to 20 gal. of gasoline when used in an internal combustion engine. In liquid form the element has an energy density of 30,000 Btu/gal. Thus a 73-gal. tank would be required for an automobile, instead of the normal 20-gal. gasoline tank, as shown in Table 1. Hydrogen has about three times more energy per unit of weight than gasoline. Liquid hydrogen (LH2) must be stored at a temperature below -431°F, and a vac- uum-insulated tank is required to minimize boioff. Large-scale transportation of LH2 is now done by rail tank car, road tanker, and barge. The weight of 20 gal. of gasoline plus its storage tank on an auto is about 150 lb, whereas the equivalent amount of LH2 plus a suitable cryogenic tank would weigh about 300 lb. The same amount of H2 stored in a MgNi alloy hydride system [1] would weigh 625 lb, with its container. Replacing an auto engine with a fuel cell improves the comparison of H2 with gaso- line considerably, since the efficiency of overall conversion in a spark-ignition engine is about 15% [2], and the electrochemical efficiency of known fuel cells ranges from 50% to 70% [3]. This means that H2 may be cheaper than gasoline on a per-mile basis [2]. Fuel cells are not now competitive with the spark-ignition engine in price or performance, but with the development of cheap fuel cells synthetic fuels may become economically competitive. Note: Manuscript submitted April 12, 1974. 1 PAGENO="0685" 679 CARHART, AFFENS, BOSS, HAZLETT, AND SCHULDINER Table 1 Comparison of Various Fuels, Based on 20 Gal. of Gasoline* J~ Fuel Btu/lb Btu/ft3 Amount Equivalent to 20 Gal. of Gasoline Gal. Lb Typical gasoline Methanegas(CH4,2000psia) Methanol (anhyd CH3OH) Ethanol (anhyd C2H5OH) Liquid hydrogen (at NBP) Hydrogen gas (2000 psia) Metal hydride (Mg2Ni . H,~) Liquid ammonia (at NBP) JP-5 19,080 21,500 8,640 11,550 51,980 51,980 4,350 8,000 18,500 835,700 152,400 429,400 572,900 230,300 34,650 479,900 384,800 930,000 20.0 110.0 38.9 29.2 72.6 482.0 34.8 43.3 18.0 117 104 258 194 43 43 513 279 120 *From Ref. 1. The tbermal efficiency of a reversible heat engine working between temperatures T1 and T2 is given by the Carnot theory as efficiency (T2 - T1)/T2 Since practical heat engines are irreversible and normally operate with a lower tempera- ture T1 of more than 300 K, while the upper temperature T2 is limited by the materials of construction, thermal efficiencies in excess of 40% are seldom achieved. The efficiency of electrochemical conversion of chemical to electrical energy is not limited by the Carnot cycle. The theoretical thermal efficiency of an electrochemical cell is efficiency = L~G/L~H = - flFEr where Z~G is the free energy change and L~H is the enthalpy change of the reaction, n is the number of electrons transferred in one act of the overall reaction, F is the faraday constant (96.5 X io~ C mole1), and Er is the reversible cell potential. Generally, z~H, hence the efficiency of ideal fuel cells is close to unity. In a real fuel cell, however, energy losses due to solution resistance and electrode polarization reduce Er to an operating potential E, such that E Er - 11p - - 2 PAGENO="0686" 680 NRL REPORT 7754 where is the net voltage loss from chemical and charge transfer processes at each elec- trode, ~d is the net voltage loss from mass transport processes, and ~R is the voltage loss from the ohmic resistance of the electrolyte separating the anode and cathode. Hence, the real efficiency of a fuel cell is efficiency = - nFE/L~H. The magnitude of each voltage loss i~ increases with current drawn from the cell so that operating potential E and the efficiency of the cell decrease with increasing current. There are many problems of transporting, distributing, and storing liquid H2. How- ever, substitute synthetic fuels such as aluminum or aluminum alloys in fuel cells [4] would avoid the problems of H2 storage and flammability and substitute a cheap light- metal fuel with a high energy content. In the immediate future, H2 can serve as a clean fuel for special naval purposes, such as storing wind-generated electrical energy at remote bases. The most important character- istic of H2 is its versatility; it can serve as either a thermal or an electrochemical fuel. PROPERTIES OF HYDROGEN AS A FUEL Chemical Oxidation The convenience and flexibility of general-purpose fuels are reflected in the current energy economy, in which about 80% of the energy resources [5] consumed are for uses other than electric generation. Proper use of nuclear and solar energy requires portable and storable synthetic fuels derived from abundantly available or recycleable resources. Hydrogen can become a secondary source of energy, derived from the primary source by the decomposition of water [6]. Comparative Physical and Chemical Properties-Table 2 [7] compares physical prop- erties of H2 with those of other fuels. A comparison of the "energy density" of the fuels with gasoline in Table 1 shows some major differences. For an energy content equivalent to gasoline, all fuels listed, except JP-5, occupy more volume, but methane and hydrogen are lighter. Comparative costs of fuels are listed below. Fuel Dollars per Million Btu Gasoline 1.32 (at refinery) Methanol 2.10 Ethanol 7.30 Hydrogen 0.78-3.00 (electrolysis, estimates for future) Hydrogen 4.00-6.00 (fossil fuel processes) Natural gas 0.20 (domestic gas at welihead) Natural gas 0.70 (liquid imported at port of entry) Coal 0.15 (at mine mouth) Navy distillate 1.00 Nuclear fuel 0.05 3 PAGENO="0687" 681 CARHART, AFFENS, BOSS, HAZLETT, AND SCHULDINER Table 2 Physical Properties of Hydrogen and Other Fuels* Property H2 CH4 CH3OH Molecular weight (g/g-mole) 2.016 16.04 32.04 Freezing point (°C) Boiling point (°C) -259.20 -252.77 -182.5 -161.5 -97.8 64.7 Heat of vaporization (cal/g) 106.5 121.9 262.79 Critical temperature (°C) -239.9 -82.1 240 Critical pressure (atm) 12.80 45.8 78.5 Liquid density (g/1[temp °C]) 71[-252.77°] 425[-252.77°] 792[200] Gas density (g/l) Specific heat at STP (cal/mole-° C) 0.082t 6.89 0.7174j- 8.16 - 18.3 *After Ref. 7. tRef. 8. Methods of Combustion - H2 burners and combustion chambers will be smaller [7] than those required for natural gas. Applicances convert gas into mechanical energy either by internal (piston, gas-turbine engines) or external combustion (burners). 1. Flame burners. Most burners mix air with gas prior to burning. The gas-air mixture must travel toward the open end of the burner at a rate higher than the rate of flame propagation in the mixture. This prevents "flashback," or ignition inside the burner. If the velocity of the gas flow exceeds the burning velocity at all points, the flame is blown off. Figure 1 [9] shows flame velocities for various mixtures of some typical fuel gases with air. H2 has a very high flame velocity, particularly at less than stoichiometric air content, such as in the primary gas-air mixture, but the design and construction of appliances that use H2 present no severe problems. H2 burners are more prone to flashback than to blowoff [10]. Since the only product of combustion is water, a H2 furnace does not need a flue unless the amount of water vapor produced is excessive. 2. Catalytic burners. Various gas research projects have demonstrated the advan- tages of using catalytic burners for cooking, heating [11], and other purposes. (Cataly- tic burners have been applied to specific Navy uses; for example, the removal of atmospheric contamination in submarines.) A catalytic burner for H2 does not require preignition, but natural gas requires a pilot, or electrical preheating, to initiate combustion. There are two types of catalytic burners for H2. The low-temperature burner is about 70%-porous ceramic plate. The internal surface of the plate is coated with a catalyst; a platinum metal is best, but cheaper materials may be found. Air is mixed with the H2 and fed through the porous plate. Flameless combustion occurs within the plate. At low output, the burner can operate at 300 to 500° F with no fire hazard. The high-temperature catalytic burner, which operates at temperatures above 1000° F, requires a backing for the catalytic surface [7]. 4 PAGENO="0688" 682 NRL REPORT 7754 Fig. 1-Burning velocities of combustible gases mixed with air [9] The generation of large quantities of heat for naval applications requires special con- sideration. The design and other technical problems of really large-scale H2-fueled flame and catalytic burners have not been tackled to date. 3. Piston engines. One of the important factors in the choice of a fuel for a piston engine of the type used in land vehicles is the compression ratio. In general, high compression ratios favor higher outputs and higher thermal efficiencies. The permissible compression ratio is determined not only by the fuel characteristics, but also by such factors as mixture ratio, size and speed of engine, combustion chamber design, ignition timing, and thechanical strength. The important fuel characteristics are the flame speed and the limits of flammability [7]. Hydrogen has very wide limits of flammability when mixed with air (4% to 75% H2), which enables an engine to operate with the mixture far from the stoichiometric propor- tion of 29.6%. The very high flame speed of H2 leads to a marked tendency to "knock." However, flame speeds for all fuels are lower near the limits of flammability, and a fuel- air mixture that has an inherently high flame speed (H2-air) exhibits an acceptable burn- ing rate at a relatively lean mixture ratio. The tendency of H2 to knock and to backfire can be eliminated if the mixture is adjusted to contain at least 25% excess air [12]. King et al [13] used H2 in a test engine at a compression ratio of 10:1 without knock provided carbon deposits were absent. In an engine designed for and operated with H2, engine deposits will not build up from the combustion of fuel, but deposits from engine oil are possible. Tests [14] using H2 showed very small quantities of oxides of nitrogen in the exhaust. (1) 0 >- F- 0 0 -J Lii > LU -J 60 100 140 U PRIMARY AIR (% OF TOTAL REQUIRED) 5 PAGENO="0689" 683 CARHART, AFFENS, BOSS, HAZLErF, AND SCHULDINER Besides lubrication, there seem to be no significant obstacles to using H2 in a con- ventional piston engine. Such an engine could be a high-performance, high-compression- ratio engine with a clean water-vapor exhaust and an extended life resulting from the absence of deposit buildup. 4. Gas turbine engines. Although optimal engine parameters have not been deter- mined for an H2-burning engine, NASA successfully flew a B-57 aircraft with one of the J65 engines fueled with H2 [15]. Combustion problems should be minor for turbine engines because H2 has a very high flame velocity and can be prevaporized and premixed with air. These facts point to smaller, lighter engines than are possible with petroleum fuels. Carbon deposits in combustors would be greatly reduced and possibly eliminated if bearing lubricant leaks could be minimized. Because of this and because the H2-air flame radiates at low intensities, radiation to the combustor walls could be reduced. Hence, the materials problem for higher temperature combustors would be greatly relieved, since the cooling of convective and conductive hot spots is more amenable to secondary airflow distribution. Aircraft heat exchangers would have longer life because of the lack of fuel deposits from H2, and combustor nozzle life would be extended for the same reason. Further- more, H2 has a unique advantage for hypersonic flight because it has a high specific heat and can be heated to high temperatures without degradation or decomposition. 5. Rocket propulsion. NASA has exploited the properties of H2 for large rockets. The military, on the other hand, give priority to readiness in weapons design, sacrificing the high performance which is possible with LH2/LOX missiles. Thus, although LH2 cannot be matched in some ways, it is likely that readiness will continue to dominate the military rocket design criteria to the exclusion of this propellant. Electrochemical Oxidation Despite the time that has elapsed since the principle was established in 1839 [16], no fuel cell has yet been exploited commercially. The key to the economically useful fuel cell is an overall cell reaction with a high electrical potential; cheap, stable electrodes with low overvoltages; cheap, stable fuel; and a stable, noncorrosive electrolyte of high conductivity. The difficulty is in getting all of these desiderata into a compact package that will last long enough. Unfortunately, reactions with high free energies involve re- active chemicals that are not normally stable. Stable electrodes with low overvoltage must of necessity be. good catalysts for the electrode reactions and must have a large electrode area (high porosity). The best and most stable catalysts are usually the plat- inum metals and the cost of both the electrode materials and the porous construction is high. The most suitable electrolytes are usually corrosive strong acids or bases. Much progress has been made in developing useful fuel cells, but the progress has been too dependent on costly trial and error. There is no complete theory of either catalysis or electrode processes that allows prediction of the necessary characteristics. A large number of thermodynamically favorable chemical reactions have not been realized 6 62-332 0 - 76 - 44 PAGENO="0690" 684 NRL REPORT 7754 because there are no methods for catalyzing them. Table 3 [17] gives thermodynamic data on some H2 fuel-cell reactions. Table 3 Maximum Performance of Various H2 Fuel-Cell Reactants* Reaction [ ~G°, kcal/mole 1 E°(volts), 25o~[ W-hr per pound 1/2 H2(g) + 1/2 F2(g)-'HF(aq) 66.1 2.87 1740 03(g) + H2(g)-*02(g) ÷ H20(l) 95.8 2.07 1010 H202(l) + H2(g)-'2H20(l) 85.2 1.85 1240 1/2H2(g) ÷ 1/2 Cl2(aq)-~HCl(aq) 33.0 1.43 476 H2(g) + 1/202(g)+H20(l) 56.7 1.23 1660 1/2H2(g) ÷ 1/2Br2(aq)-+HBr(aq) 25.6 1.11 168 Fe3~(aq) + 1/2H2(g)-+Fe2~(aq) + HF(aq) 17.77 0.77 164 H2(g) + 13 (aq)-+2H1(aq) ÷ 1(aq) 24.7 0.53 51.0 *Ref 17. Working H2/02 Fuel Cells- In terms of electrochemical reactivity and energy con- tent per unit weight, H2 remains pre-eminent. The H2/02 fuel cell operates best with either a strong acid or alkali electrolyte because these solutions are good ionic conductors and their large buffer capacity maintains constant pH and potential.~ The anode reactions are H2 = 2H~ + 2e(acid) H2 + 20H 2H20 ÷ 2e(alkali). The cathode reactions are 1/202 + 2H~ + 2e = H20 (acid) 1/202 + H20 + 2e = 20H (alkali). Since reactions involve three phases, fuel cells require a highly porous, solid structure in which a stable gas-liquid interface can be established. Both anode and cathode reac- tions require catalysts to promote the electrode processes. These catalysts must also be electronic conductors, be resistant to corrosion, and not be poisoned by impurities. A small amount of direct reaction of H2 with 02 occurs because of solubility in the electrolyte. This generates heat and reduces efficiency. As current is increased, efficien- cies decrease from about 90% to 50% at maximum power levels. This directly affects mission times, especially for space and undersea applications, where size and weight impose severe limitations. 7 PAGENO="0691" 685 CARHART, AFFENS, BOSS, HAZLETT, AND SCHULDINER As design temperature increases, heat rejection becomes easier, reaction rates increase, and the need for catalysts decreases. However, corrosion and stability problems increase. For continuous operation, products must be removed at the same rate that reactants are introduced. For pure H2 and 02, the cell is self-regulating, requiring only a constant- pressure gas feed. For an air-fed cell, air must be pumped at a rate proportional to the current drawn, and the excess air must be vented to prevent accumulation of nitrogen. Water can be evaporated into the vented airstream, but in an H2 /02 cell an alternative method for removal is required, such as recirculation of the moist H2 in the cell through a condenser or a wick. The fuel-cell battery [18,19] is a multiple stack of electrochemical cells connected in series to yield the required voltage. Each cell is fed with gas at the same rate. The cell stack is equipped with a heat-removal system, temperature control, fuel supply, oxi- dant supply, water-removal system, and electrical output. A control device coordinates all these operations. The power output is a variable low-voltage direct current and is conditioned to the required output. Thus even a simple H2/02 fuel-cell battery is a complex chemical engineering system requiring far more than just electrochemical com- ponents. Table 4 [20] lists a variety of H2/02 fuel cells that have been developed. Table 4 H2/02 System Accomplishments* Corporation Item Power System Date Allis-Chalmers Tractor 15 kW H2/KOH/air 1959 General Electric Manpack, military 200 W H2/IEMt/air 1961 General Electric Westinghouse Gemini, power source Cell stacks 1 kW 100 W H2/IEMt/02 C0-H2/SE~/air 1964 1965 Pratt and Whitney Apollo, power source 1.5 kW H2/KOH/02 1966 Allis-Chalmers Field power, military 5 kW H2 § /KOH/alr 1966 Union Carbide Minibus 32 kW H2/KOH/02 1966 Texas Instruments Field power, military 1 kW CO-H2 II /M2C03/air 1969 Pratt and Whitney Residential power 10 kW H2 **/H3P04/air 1971 Pratt and Whitney Power module, DSSV 20 kW H2/KOH/02 1972 *Ref. 20 tIEM = ion exchange material. jSolid electrolyte; (Zr02 )085(CaO)015. §Steam-reformed hydrocarbons and Pd-Ag diffusion. iPartial oxidation of hydrocarbons. **Steam.reformed natural gas and shift reactor. The GE Gemini cell (Fig. 2) [18] used as the electrolyte an ion-exchange resin in the form of a thin sheet of a sulfonated polystyrene that behaved as a strong acid. The elec- trodes were platinum black embedded in the surfaces of the sheet and in contact with cooled current-collector plates made of titanium or tantalum. The Gemini system 8 PAGENO="0692" 686 NRL REPORT 7754 ACCUMULATOR contained 96 cells, each 8 in. by 7 in., arranged in three modules of 32 cells. The 1-kW unit was 25 in. long and 12.5 in. in diameter, and it weighed 68 lb. In addition, auxiliary pump- ing and control equipment was provided for the H2, 02, and coolant. Both the Gemini and Apollo fuel-cell batteries were designed specifically for space operation, where fuel efficiency and reliability are crucial. Similar batteries for earth use are likely to have different characteristics. Because fuel cells operate with relatively few moving parts, they are quiet and can be installed close to the user. An extensive test program for fuel cells powered with H2 generated from reformed natural gas is now under way. This is the TARGET program, which uses the Pratt and Whitney 12.5-kW fuel cell and is sponsored by 32 natural gas companies. About 60 experimental fuel-cell powerplants are being installed to generate electricity onsite in apartment buildings, offices, banks, light-industry buildings, and single-family homes. Another major program, being conducted jointly by Esso Research and Development Company and France's Compagnie General d'Electricith'[21], concerns the French- developed Alsthom thin-electrode fuel cell. Comparison Among Fuel Cells and Other Energy Converters-Figures 3 and 4 [19] compare energy with volume and weight for several electrical devices. Figure 5 gives Fig. 2-Schematic arrangement of Gemini fuel-cell system [18] 9 PAGENO="0693" 687 CARHART, AFFENS, BOSS, HAZLETF, AND SCHULDINER FUEL CELL 28,000 - I-KW.H2-02 CELL ~//////- ,,/~ERI LIQ.H2& 02 24,000 - ENG.-GEN. SET t 20,000 I-KW. UNIT AT FULL LOAD, GASOLINE a LIQ. 02 ~ 16,000 - ENG-GEN. SET I-KW. UNIT AT FULL 12,000 - LOAD, LIQ. H2 8 02 (2 cc ~ 8,000 - ES w 4,000 SILVER-ZINC LEAD- ACID I I C0 I 10 100 1,000 TIME (HR) Fig. 3 - Energy-volume ratios for fuel cells, batteries, and engine-generator sets [19J 1000 >- (2 cc z w ENG.-GEN. SET I-KW UNIT AT FULL LOAD, LID. H2 6 02 Fig. 4 - Energy-weight ratios for fuel cells, batteries, and engine-generator sets [19] 10 PAGENO="0694" 688 NRL REPORT 7754 FUEL CELLS 50 70 80 SOLAR CELLS ____ PRESENT 5 15 30 RANGE IC. ENGINES & GENERATORS ~PROJECTED I V//A RANGE 20 25 DIESEL ENGINES 8 GENERATORS 25 35 GAS TURBINES & GENERATORS I__ IS 25 STEAM TURBINES & GENERATORS 30 42 MAGNETOHYDRODYNAMICS* 55 THERM OELECTR ICS 610 20 THERM ION ICS 8 5 45 *Efficiency as topping stage with steam turbine; demonstrated efficiency is 8% (Ref. 22) Fig. 5-Efficiencies of energy-converting devices in percent [19] efficiencies of conventional engines using fossil fuels and fuel cells using inorganic fuels. The prices of inorganic fuels and fuel cells are still a long way from being economically competitive with those of heat engines using organic fuels. Fuel cells will become com- petitive with conventional energy sources only when a number of economic and techno- logical objectives have been reached. A review [23] of the prospective use of fuel cells for surface naval propulsion concluded that although low- and high-temperature 112 cells are potentially favorable economically, the requirements for surface naval propulsion are a long way from being met. The use of fuel cells must await the improvement of power- to-volume ratio and the construction of fuel-battery assemblies that have outputs in the megawatt range. In the long term, the potential for fuel cells is promising. Small submarines and other submersible vessels equipped with 112/02 low-temperature cells [23] will have operating times 10 to 30 times those of submarines propelled by the same volume of conventional lead-acid batteries. Fuel cells are competitive with batteries in small- and medium-sized submarines for operating times of less than a month. Figure 6 [24] compares the weights of the most promising candidates for powering deep-ocean vessels as a function of mission duration and design depth. The three top- ranked fuel-cell systems-H2/02 gas reactants stored in hard tanks at 6,000 psi; H2/02 cryogenic liquid; and hydrazine/oxygen (N2H4/02) stored in soft tanks at ambient sea pressure-were shown to be relatively competitive at the Deep Sea Submergence Vehicle (DSSV) design depth (Fig. 6). Of the many chemical dynamic systems studied, the 11 PAGENO="0695" 689 CARHART, AFFENS, BOSS, HAZLETr, AND SCHULDINER 200 SECONDARY BATTERIES 1000 - SEARCH 800 H~-0~ DYNAMIC~ S2 600 - 20KW AVERAGE (CRY0GENIC)-~ 40KW PEAKS 34 HRS DURATION H2 °2 FUEL CELLS ~ 400 - (H.P GAS) iii N2H2 H202 FUEL CELLS 200 H2-O~ FUEL CELLS (CRYOGENI~) 2 4 6 8 10 20 30 DESIGN DEPTH (THOUSANDS OF FEET) Fig. 6-Power system specific weight vs design depth [24] closed-loop LH2/LOX system stored in hard tanks was best. For these dynamic systems, both Rankin and Brayton cycle conversion systems were studied. Rich and Schmidt [24] concluded that fuel cells are the best power system for DSSV. The problem for DSSV now reduces to selecting the best fuel-cell system. Much work on the N2H4/02 and hydrogen/peroxide (H2/H202) fuel cells for underwater use has been done at the Naval Ship Research and Development Laboratory in Annapolis, Maryland [25]. The NSRDC work included simulated deep submergence to 6000 ft, using a N2H4/ H202 system with an output of 1.8 kW at 18 V. Further work on both the cryogenic H2 /02 and the hydrazine fuel cells is necessary before a final selection of the best system can be made. HYDROGEN PRODUCTION Since elemental H2 is not found in our environment in significant amounts, it must be manufactured by applying energy to a hydrogen-containing compound, usually water. One generally chooses the least expensive available manufacturing process, but for the Navy's needs, convenience can also influence the choice [5]. For example, if nuclear energy is available, one may choose to produce H2 by theoretically economical thermal processes, or the thermal energy could be converted to electricity for electrolysis of H2 0. Each Navy problem must be evaluated in terms of each energy source; the economics of the various processes are compared in the "Production-Cost" section. About 3 x 1012 SCF of hydrogen is manufactured each year, most by the economical method of steam reforming of natural gas, but some by electrolysis where inexpensive energy (e.g., hydroelectric power) is available. However, future methods and costs will depend on the acceptance of the H2 economy by the nation and world. Furthermore, dwindling fossil-fuel resources will limit the production of H2 from these materials in the long term. 12 PAGENO="0696" 690 NRL REPORT 7754 Fossil Fuels Today, fossil fuels are the most economical source of large volumes of H2. The same technology is applicable to other sources of organic matter. The specific process used depends largely on the physical state of the raw materials: gases, liquids, or solids. All these techniques use the thermal splitting of H20 molecules, deriving the energy from fuel oxidation. Steam Reforming of Volatile Hydrocarbons-This will likely be the major process for producing H2 until 1980 [26]. A desulfurized hydrocarbon gas is combined with steam in a reformer furnace to produce H2, carbon monoxide (CO), and carbon dioxide (C02) over a catalyst bed (generally Ni). The CO is removed by subsequent reaction in a catalytic shift converter to form more H2 and CO2.. The reactions are as follows 1500° F CH +nHO ~-nCO+(2n+1)H2 n 2n+2 2 Cat. 350 psig Cat. nCO + nH2O ~ nCO2 + nH2 Summary: C~H2~÷2 + 2nH2O -k- nCO2 + (3n + 1)H2 The reaction is endothermic, requiring heat. CO2 is removed by standard techniques. The process would be greatly improved by the development of rugged catalysts that would be less susceptible to feedstock poisoning, yet effective at lower temperatures and pressures. Partial Oxidation of Heavy Petroleum Fractions-This process can work with any petroleum fraction, but cannot compete economically with steam reforming where the latter can be used. It seems likely that this process will be a major source of 112 between 1975 and 1985 [26]. A partial oxidation of the petroleum stock produces a synthesis gas of H2 and CO while releasing the heat required for the shift reaction of CO to H2 and CO2 as follows: Gasification: 2CnHm + nO2 --2nCO + mH2 Shift: 2nCO + 2nH2O -*~ 2nCO2 + 2nH2 Summary: 2CnHm + 2nH2O + nO2 -~- 2nCO2 + (2n + m)H2 The reaction is less efficient than steam reforming because some of the heat generated by oxidation cannot be used effectively. In addition, the oxidation requires, instead of air, pure 02, which requires additional energy and cost to produce. Coal Gasification-The abundance of coal in the United States makes coal-conversion processes attractive. Processes to produce pipeline gas (CH4) are in the pilot-plant stage [8,27], and the feasibility of 112 production has been established [26]. As in steam reforming, the feedstock is reacted with 1120 at elevated temperatures (the reaction is endothermic) to form a synthesis gas which is subsequently treated with steam (shift reaction) to produce more H2. Physical preparation and heating of the coal feedstock are costly. The main reactions in a steam-oxygen process are as follows, for bituminous coal 13 PAGENO="0697" 691 CARHART, AFFENS, BOSS, HAZLETF, AND SCHULDINER represented as carbon: Oxidation: 3C + 202 ~ CO2 + 2C0 + heat - 1600-1800°F Gasification: 3C + 3H2O + heat -~ CO + CO2 + H2 + CH4 450 psig The synthesis gas composition is more complex than shown because coal contains S and N compounds. The production plant is also complex because of the necessity of converting from solid to gas and the need for expensive pure 02. Nonfossil fuels Since H2 can be produced in many ways, imaginative suggestions have emerged from diverse sources. Plants-These can be the source of organic molecules for production of H2, as in coal gasification above. On the other hand, combustion of plants can provide the necessary energy for thermal or electrolytic production of H2. The plant sources include, but are not limited to, mariculture, agriculture, and municipal rubbish. Bioconversion-It has been proposed that microorganisms may be developed that can synthesize H2 directly using solar energy [28]. Decomposable Compounds-Many compounds decompose when heated to yield H2 (e.g., NH3 and metal hydrides). Since these systems could be considered as H2 storage, they are discussed later under "Storage." Exothermic Reactions-Since the heat from any exothermic reactions can be used to produce H2, one must consider an enormous list of reactions as candidates for H2 production or storage. Some specific systems that release H2 directly (e.g., Al + alkali) have special importance for consideration as H2 storage. Electrolysis A General Electric water-electrolysis process based on solid-polymer electrolytes (SPE) has been proposed [29]. It was assumed that beyond 1985 an inorganic solid electrolyte would replace the solid-polymer electrolyte and that between 1985 and 2000 the system would operate at about 1000°F with an electrical input of about 84 kWh per 1000 SCF of H2. The conventional electrolytic process requires 150 kWh! 1000 SCF. Commercial water-electrolysis processes now require about 8 gal. of makeup water per 1000 SCF of H2. Based on this, the water necessary to produce enough H2 to meet projected energy requirements from 1985 until 2000 will range from 500 to 2400 billion gal. of water a year. This represents only a small fraction of our present water consumption, which is about 400 billion gal. each day for the entire United States. 14 PAGENO="0698" 692 NRL REPORT 7754 For every ton of H2, 8 tons of 02 are produced by electrolysis of water. Therefore, if large quantities of H2 are produced, the 02 production will be many times the present world consumption. However, some of this 02 could be used for specific naval applica- tions such as rocket and submarine propulsion. Seawater or concentrated seawater (a byproduct of desalting) can be used in an electrolysis process to produce H2, but yields Cl2 and NaOH rather than 02. However, the power required per unit volume of H2 would be doubled, and disposal of the Cl2 and NaOH would pose a problem. Thermal Energy All sources of energy can be converted to thermal energy with a theoretical con- version efficiency of 100%. However, thermal processes for producing H2 are Camot limited and do not have high energy efficiencies. Yet, thermal processes have tremendous potential for energy sources that begin as heat since the efficiency of conversion of heat to other energy forms is itself limited by thermodynamic principles. Nuclear, solar, and geothermal sources of energy could provide this heat directly. High-Temperature Water Decompositior~-At temperatures around 4000°C, H20 is split into H, H2, 0, and 02, but no process exists for separating these species efficiently before they can recombine. Solar furnaces may provide the required temperatures, but currently envisioned nuclear reactors will operate at temperatures below 700°C [301. Low-Temperature Water DecompositionSince heat is commonly available directly from many sources, multistep closed-reaction systems are being considered for H2 production from H20 [30-331. These cycles are Camot limited to efficiencies of about 85% in theory and perhaps 65% in practice [32], but ecological advantages of regenerating all materials except H20 are significant. Thermodynamic constraints make two-step processes such as the following unlikely: H20 + X-~X0 + H2 X0 -~X + 1/202 where X is any appropriate atomic species. However, multistep processes are not only possible, but commercially interesting [32], though none have been run in large-scale tests. Numerous reaction schemes are being compared by computer analysis [30] and by chemical reasoning [31-32]. A typical three-step suggestion is as follows [31]: 300 K LiNO2 + 12 + H20 -~ LiNO3 + 2H1 700 K 2HI-~-I2 + H2 750K LiNO3 LINO2 + 1/202. 15 PAGENO="0699" 693 CARHART, AFFENS, BOSS, HAZLE~[T, AND SCHULDINER The overall efficiency is limited by the temperature range 300 K to 750 K because each step of the process must occur in a separate reaction chamber with the usual com- plexities of operating a chemical plant. Thermal processes are in such an early stage of development that further research is needed before they can be evaluated properly. Production-Cost Summary Today's price for LH2 is $4 to $6 for 106 Btu (20-30 cents/lb), depending on the size of the plant [6,341. This price makes H2 cost $24 to $36 for an amount that has an energy content equivalent to a barrel of fuel oil. Steam reforming of oil or natural gas, the cheapest method for H2 production, is the process now used commercially. Increasing the reforming plant size from 30 to 2500 tons per day might reduce the price to $1.60 per million Btu [26]. Steam reforming is not a practical, long-term, large-scale process, however, since it requires natural gas as a raw material. The proposed "hydrogen economy" will produce H2 by electrolysis, the electricity coming from large nuclear reactor plants. Thus, the cost for electricity will determine in a major way the cost of LH2. Winsche, Hoffman, and Salzano [5] formulated the effect of electrical cost on H2 production cost. Putting their formula in terms of one million Btu of H2 (thermal equivalent), we obtain cost of electrolytic H2 0.38 g, where g is the cost of electricity in mills/kWh. The cost of transportation and distribution, which is higher for H2 than for distillate fuels, must be added. Cost at the plant site is tabulated below for several electricity rates. g Cost for 106 Btu (mills/kWh) (dollars) 1.0 0.38 2.0 0.76 4.0 1.52 6.0 2.2~ 10.0 3.80 Predictions of rates for electricity from nuclear power plants cover a wide range. Further, the influence of potential power sources, such as liquid-metal fast-breeder reactors and fusion reactors, on rates cannot be defined. CDR Moore of the Navy Petroleum Office reported the following prices being paid in 1973 for distillate fuels [35] 16 PAGENO="0700" 694 NRL REPORT 7754 Fuel 106 Btu Barrel (dollars) (dollars) Navy Distillate 0.95 5.50 JP-5 1.17 6.80 JP-4 1.09 6.30 Diesel 1.17 6.80 Distillate fuel prices have increased drastically in recent years, and further significant but unpredictable increases will occur by the year 2000. Thus, although the current price of H2 far exceeds that of distillate fuels used in the Navy, this may not be the case in 10 to 20 years. The price per energy unit is certain to be higher, however, for any fuel, and the Navy fuel bill will be 2 to 3 times the 1973 bill if operations are continued at current levels. Development of alternate liquid fuels from oil shale and coal could stabilize the price at the lower value. Figure 7 shows the historical pattern for relative costs for H2 and JP fuel, with the JP cost in 1950 taken as 1 [36]. The dramatic decrease for H2 since 1955 is levelling off, but projected costs [26,37] indicate that H2 and JP may cost about the same in 2000. 0 100 50 o 0 LH2 0 0 ,-HISTORICAL V I __________________________________ 1950 960 970 980 990 2000 YEAR Fig. 7-Future fuel cost [361 Commentary The Navy may pursue special applications for H2 fuel. For instance, small submersibles could be powered with H2/02 fuel cells, and remote bases may use environmental energy sources to generate hydrogen for heating or energy storage. These limited uses do not depend on large-scale conversion to H2 fuel by the civilian sector. Adequate supplies of H2 fuel for DSSV's is commercially available today in the United States, but continuous 17 PAGENO="0701" 695 CARHART, AFFENS, BOSS, HAZLErr, AND SCHULDINER operation with such craft in distant areas would require H2 production on a mother ship. Seawater electrolysis is a preferred process in this situation in spite of the higher power requirements. Remote bases could also produce H2 by electrolysis, using wind power or solar energy to generate the electricity. If the Navy converts major elements of the fleet to LH2, U.S. production must be increased. Since the Navy is a minor consumer in the total fuel picture, Navy conversion to H2 might appear feasible. However, because of the complex interactions with national fuel factors we feel that significant use in the Navy could come only with national adoption of the "hydrogen economy." Since large Navy usage of H2 cannot be envisioned before 1990 because of the capital investment in current ships and aircraft, steam reforming and partial oil oxidation processes will not be important to the Navy fuel picture. Coal gasification will probably be the major H2 production process from 1980 until the time when nuclear energy con- tributes a large fraction of our national power. HYDROGEN STORAGE Despite its high energy content per unit weight, the low energy content per unit volume of H2 increases the size and cost of storage facilities. Storage as a gas for industrial and residential purposes can be handled much like natural gas storage, but storage as a liquid on craft such as ships and planes requires significant departures from current practice with liquid fuels. Storage as a Gas If the nation converts to an H2 economy, many natural-gas storage facilities can be adapted for H2. The Institute of Gas Technology [30] states that depleted gas and oil fields as well as aquifer rock formations can be used for high-pressure H2 storage, as they are for natural gas. Mined caverns and salt cavities show less promise. Natural-gas storage vessels can also be converted to H2 use, but the effects of hydrogen embrittlement at higher pressures (3000 psi) must be considered. The low volumetric heating value of hydrogen can be increased by increasing the pressure. However, this increase is not as great as it is for natural gas because of the difference in compressibility factors. Thus the ratio of Btus per unit volume for H2/natural gas de- creases from 0.32 at 1 atm to 0.21 at 2400 psi. A potential Navy interest in H2 gas is its use at shore facilities. A station would tie into a commercial H2 distribution system, and only limited onbase storage facilities would be required. Vehicular storage of H2 gas for fuel use need not be considered because of the low volumetric heating content. Embrittlement in the transport and storage of hydrogen was recently reviewed by Bever [38]. Liquid hydrogen appears not to cause hydrogen embrittlement of steel. Sys- tems of steel pipelines and storage tanks, based upon current technology, that are now in use are 18 PAGENO="0702" 696 NRL REPORT 7754 1. high pressure hydrogen tanks 2. processing equipment for hydrogen in the chemical and petroleum refining industries 3. distribution of manufactured gas which contains more than 50% H2 4. two pipelines, one in Texas and one in Germany, reported to carry H2 over appreciable distances. A body of technology for transport of H2 is available, but an intensive investigation of industrial experience should be made. According to the Metals Handbook [39] at temperatures under 400°F, carbon steels are satisfactory at least up to 10,000 psi. These are the steels now used in long distance pipelines and gas distribution systems in cities. The special problems of welds are well known and even though further studies are re- quired, real systems are now in operation. Recent papers [40a-40c] review the current state of knowledge of hydrogen embrittlement. Storage as a Liquid NASA pioneered LH2 usage in the space flight programs. Two 900,000-gal. spherical vacuum-jacketed containers are part of the Apollo complex at the Kennedy Space Center. Daily boiloff losses from these tanks are 0.05% [30]. This type of design is limited in size to about 3 million gal., and the vacuum-jacketed insulation required in the construc- tion is much more expensive than the dry-gas-purged perlite insulation which is satisfactory for liquefied natural gas. Boiloff losses from the latter construction would be 1-3% per day for tanks with capacity of 400,000 to 5 million gal. [26] and boiloff cost would be in the range of $500,000 to $2,500,000 per tank per year. In addition, this type of tank requires a purge gas which will not condense at the boiling point of H2. Helium is too valuable to assign to this purpose and H2, the only other gas noncondensable at this temperature, has a high thermal conductivity. Hallett [261 considered the design of aboveground, nonspherical, single-wall storage tanks. External insulation affords better performance than intertial insulation, but the boiloff losses are high, similar to those for the gas-purged spherical tank design. Hallett also considered underground LH2 storage. Internally insulated prestressed concrete tanks have been used for liquefied natural gas (LNG) and have the most advantages for under- ground LH2 storage. The Chicago Bridge and Iron Co. designed and built LH2-carrying barges for NASA [41]. The capacity of the storage tanks was 240,000 gal., and the thermal barrier be- tween two concentric cylinders was 23 in. of evacuated perlite. This insulation limits boiloff to 0.25% of capacity per day. Large liquefied natural gas tankers (12 million gal.), which use nonevacuated insulation, exhibit boiloff rates of 0.25% per day [421. The gas boiloff provides a portion of the engine fuel for some tankers. Since evacuated tanks cost too much for LNG storage, no background information is available for the potential use of evacuated, insulated tanks on large LH2 tankers. Vehicle storage tanks, even on new construction, would exhibit larger boiloff than the LH2 tanks just described. Factors that account for this are (a) smaller capacity tanks 19 PAGENO="0703" 697 CARHART, AFFENS, BOSS, HAZLErF, AND SCHULDINER with higher surface/volume ratios, (b) impracticality of spherical tank design, and (c) the problem of maintaining vacuum in vehicle tanks. We estimate that boiloff losses on large ships such as aircraft carriers would exceed 3% per day and losses of greater than 10% per day would be expected for Navy fighter planes, assuming single-wall, externally- insulated, nonsphericai tanks. Witcofski [36] states that flightweight, evacuated LH2 tank construction has not been successful. Unconventional Storage Methods At normal temperatures, greater quantities of H2 can be stored per unit volume by means other than conversion to liquid. The most exciting concept is the reversible addition of H2 to specific metals or alloys such as Mg2Ni. This alloy can absorb twice the amount of H2 per ft3 as can be stored as LH2 [43]. Although only a modest pressure is re- quired, a tremendous weight penalty is imposed. Naval carrier aircraft, which are weight limited, cannot accept such an increase in operating empty weight. The metal-hydride concept exhibits more promise for shore and ship storage of H2. A severalfold improve- ment in adsorption capacity would spark new interest in this type of storage, and con- tinued study on metal hydrides is in order. Hydrogen can be chemically combined as a means of overcoming cryogenic storage problems. The most likely chemical, ammonia, has a low energy content on a weight basis as well as a volume basis and is much inferior to hydrocarbon fuels from both standpoints. A third concept involves storing an active metal that produces H2 by reaction with water. Thus aluminum, lithium, boron, and other metals might relieve the problems of LH2 handling in some applications. These three metals have H2 volumetric energy con- tents equal to or greater than that of LH2. This type of H2 storage faces weight penalties just as the metal hydride idea does. In addition, regeneration of the metal oxide is im- practical in most Navy systems, refueling procedures are unfavorable, and cost is pro- hibitive. However, it should be considered for special, volume-limited, short-range missions. H2 Liquefaction Energetics Cooling H2 gas to its boiling point and converting the cold gas to liquid theoretically require 1600 Btu/lb of energy [30]. Since H2 liquefaction processes operate at very low temperatures, overall efficiency is very low. Hallett [26], assuming some technological advancements over the present state of the art, predicts that even after 1980 liquefaction energy consumption will be 4.46 kWh/lb (15,000 Btu/lb). This processing energy amounts to 29% of the energy released (51,571 Btu/lb) from H2 combustion. LIQUID HYDROGEN USAGE IN THE NAVY Comparison of LH2 and Petroleum Fuels for Today's Fleet Most fuels used by the Navy have high flashpoints. Fuels for primary ship propulsion, Navy Special Fuel Oil (NSFO) and Navy Distillate (ND) fuel, have a minimum flashpoint of 20 PAGENO="0704" 698 NRL REPORT 7754 150°F, whereas the major aircraft fuel, JP-5, has a minimum flashpoint of 140°F. The use of fuels with such low volatility brings distinct safety advantages to Navy operations. For instance, military aircraft using JP-5 have a lower percentage of fires during crash landings than aircraft using JP-4, a fuel used by the Air Force which has a flashpoint of 0°F or lower [44]. Also, the Navy ship and aircraft turbine fuels may be stored almost anywhere a tank can be built into a ship since the vapor concentration in the space above these fuels is too low to be flammable. The Navy even stores fuels in the skin tanks of ships to provide protection against torpedo attack. The flexibility of locating fuel tanks in many parts of a ship increases fuel capacity and hence reduces the limitations on tactical and strategic operations. Storage of LH2 on today's ships would greatly increase the fire and explosion hazard, cut the storage capacity on an energy basis by a factor of four, and require major overhaul of all fuel storage, pumping, piping, dispensing, and burner facilities. Installing the required insulation on storage tanks and pipelines would be prohibitive in cost even though these changes are not completely impossible on a physical basis. Fuel tank capacity on the "Forrestal"-class aircraft carriers is 7,828 tons of boiler fuel and 5,882 tons of aviation fuel [45]. If the same tanks were used for LH2 storage, the weight of H2 would be only 1160 tons because of its low density (even without reducing tank volume by addition of insulation). On an energy comparison, LH2 stored on a "Forrestal"-class cartier could supply only 25% of the fuel value available from cur- rent fuels. To maintain the same current state of readiness, the Navy would have to refuel at sea four times as often. Thus, this hazardous operation would be needed every day in many operational situations if H2 replaced current petroleum fuels. With respect to current aircraft, use of H2 fuel would be structurally impractical and tactically unwise. To minimize evaporation losses, LH2 tanks must have low surface! volume ratios. Further, the required insulation precludes the use of integral tanks which combine the dual purpose of fuel storage and structural strengthening. Only fuselage and! or pod tanks could store LH2 in fighter and attack aircraft [46]. These factors, in addition to the low density of LH2, restrict the capacity for energy storage. The low density of LH2 is a major restraint by itself and would reduce the range of current carrier- based aircraft by a factor of three. Thus, we conclude that a change to LH2 would severely compromise current Navy fleet operations. Present ships and aircraft would require drastic overhaul and would have significantly decreased military capability. Usage In Fleet Mter Year 2000 In new construction, the Navy could integrate a novel fuel usage, such as LH2, into ship and aircraft design. Fuel storage and piping systems , including cryogenic insulation, would be a major design consideration. Ships-Although a ship designed and built for H2 fuel would present no unique struc- tural problems, energy capacity comparable to present vessels would require radical new 21 PAGENO="0705" 699 CARHART, AFFENS, BOSS, HAZLErP, AND SCHULDINER concepts and/or operations. A naval vessel is limited in volume since it must be sized to accomplish a specified mission and attain a minimum performance. It would be necessary either to: 1. Retain current vessel sizes but increase the volume available for fuel storage and/or increase propulsion efficiency or to 2. Increase vessel size but develop methods to reduce drag. Without enlarging vessels, instrumentation and automation could be increased to perform ship functions and hence reduce crew space, and the functions of each vessel could be specialized so that space assigned to other types of storage or operations could be converted to fuel storage. The propulsion efficiency could be improved by raising pressure in ship boilers and raising temperature in gas turbines to attain more effective use of fuel, and by developing other conversion devices, such as H2 /02 fuel cells, which have inherently greater efficiencies. Increasing vessel sizes would require extensive development of recent vessel design innovations, such as hydrofoils and surface-effect machines, and vigorous research in the field of drag-reducing agents. For safety, LH2 fuel should be stored far from the skin in any new ship design. In addition, heavy armor plate is needed to protect H2 storage areas, a design principle used for aviation gasoline storage on aircraft carriers. Operation of naval ships on LH2 would be marginal from many aspects-logistics, tactics, safety, cruising range, and strategy. Aircraft-The aircraft industry and NASA have developed many proposals for vehicles burning LH2 [47-49]. These proposals cover a wide speed range (subsonic through hypersonic) and capitalize on hydrogen's high heat of combustion per pound. This property of hydrogen is most beneficial for craft with high fuel-to-gross-takeoff- weight ratios and long ranges. Considering Navy operations, this advantage would be greatest for aircraft operating from shore stations-long-range patrol, transport, and reconnaissance planes. Short-range aircraft, fighter and attack vehicles, lose the advantage predicted for LH2-fueled systems. Harris at NASA Langley [46] studied the use of LH2 in two military aircraft, a V/STOL similar to the Harrier and a supersonic interceptor with F-15, F-14 level of performance. Mission radii of the study vehicles were identical to the Harrier and F-15. *The Harrier, a small plane of 13,000 lb empty weight, failed to show any performance benefit by conversion to LH2 although the maximum takeoff weight was decreased. The study for the fighter plane showed that use of LH2 would be detrimental to aircraft performance. Since the fuel storage volume must be increased by a factor of four and the fuel tanks must be located in the fuselage, the fuselage must be lengthened or increased in diameter. Either change increases drag; consequently this design aircraft of about 40,000 lb empty weight could not attain supersonic speed. 22 62-332 0 - 76 - 45 PAGENO="0706" 700 NRL REPORT 7754 These preliminary studies show that aircraft fueled with H2 designed for operation from carriers would be severly handicapped compared to those fueled with JP fuel. Long- range planes, transport and patrol, would exhibit advantages in takeoff weight, empty weight, and fuel efficiency if fueled with LH2. Other Factors Hazards associated with LH2 fuel impose increased vulnerability probabilities during operations on both ships and aircraft. These hazards result from the volatility, flammability, and ignition properties described elsewhere in this report. Fleet use of LH2 would require conversion of tankers to cryogenic storage, a significant modification. If future naval operations are at the same level as today, new tankers with combined capacities several times that of the current total tanker capacity would have to be built. The Navy would also have to drastically revise refueling procedures to overcome strategic and tactical operational limitations. Other Concepts Since fuel logistics and capacity at sea are major problems in LH2 usage, continuous production of this fuel on ships might be feasible. A large craft, with nuclear reactors for propulsion and H2 generation, could supply LH2 to onboard aircraft and to an accompany- ing task force. Although this concept was considered impractical in previous studies [50,511, it should be reexamined. Solar energy or other environmental energy sources need not be considered for such shipboard applications, since they are diffuse sources of power. Metal-hydride storage of H2 overcomes some of the difficulties of cryogenic storage. This concept could not be applied to aircraft, since these compounds would greatly increase the gross takeoff weight without materially increasing the fuel weight. Metal-hydride storage of H2 on volume-limited ships may be feasible, but the influences of added weight, storage efficiency, and high cost of metals on the total system need careful study. Stored LH2 could be used to cool electric conductors to drastically reduce their resistance; thus, cables and electric motors could be much smaller and the possibility of ship propulsion by electric motors could be considered. Special Applications The discussion of the use of H2 presented above has concentrated on major applica- tions in the Navy-fuel for ships and aircraft. Some small-scale uses exhibit potential for earlier adaptation to H2. Isolated shore bases could use gaseous H2 for energy storage, provided an environ- mental energy source is available. Intermittent sources, such as solar and wind power, can supply an adequate amount of total energy, but not continuously. When electricity is being generated, the excess could be used to electrolyze water and the H2 formed could be stored. Combustion of this H2 would meet the electrical power and heating needs during darkness or slack wind periods. 23 PAGENO="0707" 701 CARHART, AFFENS, BOSS, HAZLErr, AND SCHULDINER Some small submersibles, particularly those designed to operate on advanced, high- efficiency fuel cells, may benefit from H2 use. Liquid H2 usage would be limited to short- duration designs because of boiloff losses, but improved metal-hydride storage systems would offer new flexibility to the designer. Careful volume and weight tradeoff studies are needed to define this H2 application. Fuel cells or combustion devices burning H2/02 should be considered for craft that must 4iave nondetectable exhaust products. Another potential use for H2 is to power fast surface-effect vehicles. Liquid H2 would be the preferred form, since weight is important for such craft. Again, high propulsive efficiency is essential. Evaluation based on craft mission, cruise range, and cruise duration would optimize vehicle size. HAZARDS IN THE STORAGE, TRANSPORTATION, HANDLING, AND USE OF LIQUID AND GASEOUS HYDROGEN History Hydrogen is highly flammable, but despite the fact that it has been used with com- parative safety for a variety of industrial purposes for many years, there is widespread fear of the hazards in its use. The Hindenburg airship disaster in 1937, because of its sensa- tional nature, no doubt contributed to this fear which has been aptly referred to as the "Hindenburg syndrome" [52]. Nevertheless, both liquid and gaseous hydrogen can be used safely so long as its properties are known and understood and provided strict safety codes are developed and scrupulously observed. Considerable experience over the years has resulted in safe handling procedures and safety codes for storing and piping heating gas to homes and industry. Manufactured gas has been extensively used for many years with relative safety despite its high flammability and toxicity. It consists of high concentrations of hydrogen (up to 60%) and carbon monoxide. Natural gas, which has largely replaced manufactured gas, consists chiefly of methane, with lesser concentrations of other gaseous hydrocarbons. Natural gas is also highly flammable and, as in the case of manufactured gas, must be used with great care. The flammability concentration limits in air of four representative gaseous fuels are shown in Table 5. Note that hydrogen has a wide flammable concentration range compared to natural gas (and other hydrocarbons). Acetylene and water gas, an example of a gas manufactured from coal, also have wide flammability ranges. However, experience with hydrogen-containing gases to date suggests that a safe technology should be possible for pure hydrogen gas. Liquid H2, because of its cryogenic nature, will require advanced safety procedures if it is to be used widely in industry and transportation. Some technology has been developed over the last two decades by NASA and the armed services for use of LH2 as a rocket fuel [53,54]. Strict safety codes have been adopted and practiced, so that LH2 has been used for rocket fuel with relative safety. The same would be required for any potential Navy use. 24 PAGENO="0708" 702 NRL REPORT 7754 Table 5 Typical Flammability Limits in Air of Gaseous Fuels Fuel . Flammability limits (% by vol) Lower [ Upper Range Hydrogen* Acetylenet Natural gasj- (Average Data) Water gast 4.0 2.5 5.1 7.0 75 81 15.0 72.0 71.0 78.5 9.9 65.0 *Ref 57. tRef 55. Nature of the Hazard of Hydrogen Flammability Properties of Hydrogen-The important flammability properties of hydrogen are shown in Table 6. Methane data are included in the table for comparative purposes. As noted, the flammability concentration range of hydrogen in air is wide and is greater than that of methane and most other flammable gases. This means that hydrogen leakage into a confined space will form a mixture with a greater probability of ignition. In closed air spaces, these mixtures might even detonate, but the detonation concentration range in air (18 to 59%) [64] is narrower than the flammability concentration range. Detonation is less likely to occur in open air spaces unless ignition is caused by a high- energy source such as a shock wave or a blasting cap. Replacement of air in an H2-air mixture by oxygen increases the likelihood of detonation, and a weak spark could ignite it [53]. The burning velocity in air during deflagration (about 10 ft/s) is about ten times that of methane (Fig. 1). Hydrogen detonation speeds may be of the order of several thousand feet per second [53]. The limiting oxygen concentration which will support a hydrogen flame is 5% (if nitrogen is the inert gas), about 0.4 that required for methane. Thus, flame extinguishment is more difficult. The minimum temperature necessary for hydrogen to ignite spontaneously in air (the autoignition temperature) is relatively high compared to methane and other hydrocarbons. Thus, under some circumstances hydrogen is less likely to be ignited if it comes in contact with hot objects. However, experimental autoignition temperature data, including those in Table 6, are obtained in glass vessels. If other surfaces (such as rust) which catalyze hydrogen-oxygen reactions are present, ignition of H2 in air might occur at ordinary temperatures. Hydrocarbons do not experience similar catalysis. At reduced pressures, however (0.2 to 0.5 atmosphere) the autoignition temperature may be reduced to about 650°F [53]. The minimum spark ignition energy necessary to ignite hydrogen-air mixtures is about one sixteenth of that for methane, and the minimum igniting current for an arc (or "break spark") is about 38% of that for methane. This means that hydrogen-air mixtures can be very easily ignited by ignition sources such as electric motors and switehes. 25 PAGENO="0709" Table 6 Selected Flammability Properties of Hydrogen and Methane Property* Hydrogen Methane Oxygen concentration in nitrogen below which no mixture is flammable (% by vol) [551 5 12 Net heat of combustion (Btu/cu ft of gas) [56] 274.9 914.5 Net heat of combustion (Btu/lb) [561 51,571 21,502 Autoignition temperature in air (°F) [53-55,57-60] t 1,072 1,001 Minimum spark ignition energy in air (mJ) [59] 0.018 0.29 Minimum igniting current (arc) in air (A) [61] 0.075 0.195 * Minimum quenching distance (in.) [59] 0.024 0.08 Maximum laminar burning velocity in air at 25°C and 1 atm. (ft/s) [62,63] 10.2 1.1 Flame temperature at stoichiometric concentration in air (°F) [64] 3,713 3,407 *Numbers in brackets refer to the References. tAverage data. PTj `Tj z w 0 Cl) Cl) z r z t,i PAGENO="0710" 704 NRL REPORT 7754 The minimum quenching distance to extinguish a hydrogen flame is about one-third that of methane, so that conventional flame arrestors intended for methane and other hydrocarbon flames would not be effective with hydrogen. Other Fire Properties of Hydrogen [53] -Pure hydrogen flames are invisible, so that the problems of damage control and fire extinguishment are complicated by the difficulty of seeing the fire. Spills of LH2 burn rapidly and steadily in a column that is vertical in still air and of the same diameter as the pool. Compared to ordinary fires, there is much less heat radiated to nearby objects. Hydrogen pool fires do not last long, since LH2 evaporates very rapidly. Although the prime danger of hydrogen leakage, or LH2 spills, is fire, another hazard must be considered. Certain metals and nonmetals lose their ductility when subject to the low temperatures of LH2 and may fracture as a result of thermal stress [54]. For this reason, large spills may present problems if the materials surrounding the spill are subject to this phenomenon. Liquid H2 is subject to contamination by condensation of liquid or solidified air from the atmosphere. Such mixtures are unstable and may explode in the presence of catalysts, ignition sources, or fric~tion. Hydrogen can react violently with oxidizers such as oxygen, chlorine, and fluorine, and contamination must be avoided. Containers for hydrogen must be purged with an inert gas, and containers that have been used for hydrogen must be purged of hydrogen before admitting air. Finely divided platinum and some other metals will cause a mixture of hydrogen and oxygen (or air) to explode at ordinary temperatures [651. If a jet of hydrogen in air impinges on platinum black, the metal becomes hot enough to ignite the gas [651. Ship Damage Control [531-The only positive way to extinguish hydrogen fires is to let them burn out under the best control possible until the flow of hydrogen can be cut off. If the flow is not stopped, measures to extinguish the flame temporarily may result in formation of highly flammable vapor mixtures which will explode when reignited. Carbon dioxide must not be used to extinguish hydrogen flames because the flame tempera- ture is high enough to reduce the carbon dioxide to carbon monoxide, a highly toxic gas. Standard dry chemicals are preferred because they make hydrogen fires visible. Other Hazardous Properties of Hydrogen [531-Hydrogen is colorless, odorless, and tasteless and cannot be detected by the senses. For this reason, hydrogen leaks are likely to go undetected. Because of low viscosities and densities, both liquid and gaseous hydrogen have very high diffusion rates, and are particularly subject to leakage. The diffusion rate of gaseous hydrogen is about 3.8 times that of air. Liquid hydrogen leaks about 100 times faster than liquid nitrogen. The fast diffusion rate can be a virtue, because spills can diffuse to a nonflammable mixture in a relatively short time. Hydrogen exists in two molecular configurations, orthohydrogen and parahydrogen. At normal temperatures, hydrogen gas is chiefly orthohydrogen, while liquid hydrogen at 27 PAGENO="0711" 705 CARHART, AFFENS, BOSS, HAZLETT, AND SCHULDINER the boiling point (-422.0°F) is mostly parahydrogen. Spontaneous conversion of ortho- hydrogen to parahydrogen may occur with a large generation of heat, and can cause con- siderable liquid boiloff. Hence, it is necessary to obtain the parahydrogen form early in the liquid-hydrogen production cycle. Special Precautions in Hydrogen Storage, Handling, and Use-Recommended practices for hydrogen storage are listed below [53,54]. 1. Leakage of containers, piping, and connections must be prevented by careful choice of construction materials and techniques. 2. The dewar flasks in which liquid hydrogen is transported and stored must be protected against breakage and puncture, such as that caused by shrapnel. 3. As with manufactured and natural gas, suitable odorants should be added to hydrogen gas so that leaks may be detected. This is of no value for LH2 because the odorant would be frozen. 4. All pressure vessels should be equipped with suitable burst diaphragms or pressure-relief valves. 5. Containers that have held hydrogen must be purged with inert gases before introduction of air or other oxidizers, and containers in which hydrogen is to be stored must first be purged of air or other oxidants. 6. Ignition sources (sparks, flames, hot objects, etc.) must be removed from areas where hydrogen is stored or used. 7. Ventilation must be plentiful in areas where hydrogen is stored or used. 8. Because of its small quenching distance, conventional screen-type flame arrestors are not suitable with hydrogen. 9. Liquid H2, as a cryogenic liquid, can cause severe damage if it comes in contact with skin. 10. The disposal of large quantities of H2 is best accomplished in remote areas by burning with air. 11. Damage control is best accomplished by shutting off the H2 supply and letting any spilled or leaked H2 burn itself out. Because of its flammability, gaseous hydrogen must be handled with great care, but the technology will not be very different from that of handling manufactured gas. Liquid H2, however, because of its cryogenic properties, presents additional problems and will require special technology. 28 PAGENO="0712" 706 NRL REPORT 7754 If hydrogen is to be used for ship or aircraft fuels, the hazards of handling and storing will be considerably more than those of handling the petroleum-derived liquid fuels of today's Navy, and these hazards will be compounded under combat conditions. The limited experience with LH2 handling, especially spills, precludes a detailed assessment of hazards. TOXICITY AND EFFECT ON THE ENVIRONMENT Engine Exhaust Burners and engines burning petroleum, or any fossil fuel, produce many undesirable products (carbon monoxide, partially oxidized hydrocarbons, sulfur dioxide, nitrogen oxides (NOx), and smoke) which pollute the atmosphere. Hydrogen fuel drastically reduces this pollution problem, since NOx is the only one of these contaminants produced. Moreover, H2-air combustors can operate in a premixed mode and at fuel-to-air equivalence ratios of less than one. Such conditions prevent high combustor temperatures on a local or overall basis, thus minimizing NOx production. Fern, who developed this proposal for aircraft turbines fueled with JP [66], has extended the concept to H2-fueled engines [67]. Thermal Pollution Energy must be expended to produce H2. Fossil or nuclear fuels may provide the power, in which case the earth must absorb an extra burden of waste heat. Use of solar energy avoids this disturbance of the global heat balance. Toxicity Hydrogen is not toxic, but gross leakage into a closed space could cause anoxia as the oxygen partial pressure is reduced by dilution. CONCLUSIONS Hydrogen has many desirable properties as a fuel. It can be burned efficiently in all burners and engines in widespread use today. Furthermore, it is a superior material for fuel cells with potential for efficiencies higher than conventional types of combustion. A high heat of combustion is the property that makes hydrogen attractive. However, the low density of liquid hydrogen negates much of the advantage obtained by the heat of combustion, particularly for volume-limited vehicles. Thus, the use of hydrogen in major ships and carrier aircraft is not promising. Special applications, such as fueling small, weight-limited craft, may be practical. Remote naval facilities, if located near environ- mental sources of energy, could use the hydrogen fuel storage and transport idea. 29 PAGENO="0713" 707 CARHART, AFFENS, BOSS, HAZLETT, AND SCHULDINER Hydrogen is not a prime fuel, but must be produced by putting energy into chemical reactions. The most promising reactions today are based on fossil fuels, with coal having long-term resource potential. An expected trend to large-scale nuclear power generators should make the electrolysis of water the favored H2 production process in the long term. The hazards of gaseous hydrogen are greater than those of most combustible gases because of the wide flammability limits and the high flame velocity. Considerable experience with hydrogen-containing gases (town gas) has shown that suitable handling techniques are available. Experience with liquid hydrogen is limited, however, and explosion hazards must be examined in detail. Storage techniques for liquid hydrogen are not satisfactory, and high boiloff losses would be experienced with containers that are satisfactory for liquefied natural gas. Hydrogen tank design for irregular shapes, as on ships and aircraft, is inadequate. The cost of hydrogen between 1990 and 2000 will be several times that of current Navy fuels for equal amounts of energy. However, the present trend in crude oil price increases coupled with the decreasing oil reserves-to-production ratio indicates that H2 will not be at as large an economic disadvantage then as it is today. The cost of H2 should not be a deterrent to its use in the Navy if system performance shows significant advantages. REFERENCES 1. "What Are the Possibilities for Synthetic Fuels?" Automotive Eng. 81, No. 7, 53 (1973). 2. J.O'M. Bockris in Electrochemistry of Cleaner Environments, J.O'M. Bockris, editor, Plenum Press, New York, 1972, p 15. 3. J.O'M. Bockris and S. Srinivasan, Fuel Cells: Their Electrochemistry, McGraw-Hill, New York, 1969, p 21. 4. "Development of a Compact High-Power, High-Energy-Density Aluminum Fuel Cell for Driving Electric Vehicles and Other Applications," Zaromb Research Corp., Passaic, N.J., Status Report, Jan. 1973. 5. W.E. Winsche, K.C. Hoffman, and F.J. Salzano, Science 180, 1325 (1973). 6. L.W. Jones, Science 174, 367 (1971). 7. D.P. Gregory, D. Y. C. Ng, and G.M. Lang, "The Hydrogen Economy," Electro- chemistry of Cleaner Environments, J.O'M. Bockris, editor Plenum Press, New York, 1972, p 226. 8. G.A. Mills, Environ. Sci. Technol. 5, 1178 (1971). 9. M.W. Thring, The Science of Flames and Furnaces, Wiley, New York, 1962, p 156. 10. J. Grumer, M.E. Harris, and V.R. Rowe, U.S. Bur. Mines Rep. of Invest. No. 5225, Washington, D.C., 1956. 11. J.C. Griffiths, C.W. Thompson, and E.J. Weber, Amer. Gas Assoc. Res. Bull. 96, 18 (1963). 12. A.F. Burstall, SAE Proc. 22, 365 (1927). 30 PAGENO="0714" 708 NRL REPORT 7754 13. R.O. King, W.A. Wallace, and B. Maliapatra, Can. J. Res. 26F, 264 (1948). 14. R.J. Schoeppel, Chem. Tech. 2, 476 (1972). 15. Lewis Laboratory Staff, "Hydrogen for Turbojet and Rarnjet Powered Flight," NACA RM E57D23, Apr. 26, 1957. 16. W.R. Grove, Phil. Mag. 14, 127 (1839). 17. L.G. Austin, "Fuel Cells," NASA SP-120, 1967, p 32. 18. A.B. Hart and G.J. Womack, Fuel Cells, Theory and Application, Chapman and Hail, London, 1967. 19. W. Mitchell, ed., Fuel Cells, Academic Press, New York, 1963, Chap. 1. 20. J.B. O'Sullivan, Proc. 25th Power Sources Conference, Atlantic City, N.J., Power Sources Conference Committee, Red Bank, N.J., 1972, p 149. 21. Advanced Battery Technology 7, No. 6, 3 (1971). 22. R. Roberts, "Energy Sources and Conversion Techniques," Amer. Sci. 61, 74 (1973). 23. J. Verstraete, D. Lefevre, R. Lefort, and J. Henry, "Fuel Cell Economics and Com. mercial Application," Handbook of Fuel Cell Technology, C. Berger, editor, Prentice- Hall, Englewood Cliffs, N.J., 1968, p 495. 24. G.E. Rich and H.R. Schmidt, "Power for Deep-Ocean Systems," Energy, L.B. Holmes, editor, Northwestern Univ. Press, Evanston, Ill., 1967, p 127. 25. R.J. Bowen, et al, Proc. Intersoc. Energy Convers. Engrg. Con!., Aug. 1968, American Chemical Society, Washington, D.C., 1968, p. 845; H.B. Urb~ch, et al, Proc. Intersoc. Energy Convers. Engrg. Conf., 1971, American Chemical Society, Washington, D.C., 1971, p. 101; H.B. Urbach R.J. Bowen, J Electrochem. Soc. 117, 1594 (1970); D.R. Gormley and J.H. Harrison, Proc. Intersoc. Energy Convers. Engrg. Conf., Aug. 1971, American Chemical Society, Washington, D.C., 1971, p. 520; H.B. Urbach, et al., Proc. 25th Power Sources Con 1.. Atlantic City, N.J., 1968, Power Sources Conference Publishing Committee, Red Bank, N.J., 1972, p 182; H. B. Urbach, et al, "Optimizing Fuel Concentration in Hydrazine Cells," NSRDC Report 3596, Sept. 1972; D.E. Icenhower and H.B. Urbach, "High-Power Density Hydrazine Fuel Cells," NSRDC Report 3934, June 1973. 26. N.C. Hallett, "Study, Cost, and System Analysis of Liquid Hydrogen Production," NASA Contract Report 73,226, Air Products and Chemicals, Inc., Allentown, Pa., June 1968. 27. G.A. Mills and H. Perry, Chemtech 3, 53 (1973). 28; L.O. Krampitz, Case Western Reserve Univ., National Science Foundation Grant GI-349924. 29. \V.A. Titteringharn and A.P. Fickett, in Eighth Intersoc. Energy Convers. Engrg. Conf. Proc., U of Pennsylvania, Philadelphia, Pa., Aug. 13-16, 1973 American Chemical Society, Washington, D.C., p 574. 30. D.P. Gregory, "A Hydrogen-Energy System," Institute of Gas Technology, Cat. No. L21173, Chicago, Ill., Aug. 1972. 31 PAGENO="0715" 709 CARHART, AFFENS, BOSS, HAZLETI', AND SCHULDINER 31. G. De Beni and C. Marchetti, "Hydrogen, Key to the Energy Market," Euro Spectra 9, 46 (1970). 32. B.M. Abraham and F. Schreiner, Science 180, 959 (1973). 33. R.H. Wentorf, "Hydrogen Sought via Thermochemical Methods," Chem. Eng. News 51, 32 (Sept. 3, 1973). 34. Chem. and Eng. News, 50, No. 28, 27 (July 10, 1972). 35. W.J. Moore, "Navy Fuel Requirement Projections," Proc. Workshop on Navy Alternate Energy Sources Res. and Dev., Naval Ship Research and Development Center, Bethesda, Md., Report 4195, J.R. Belt and H.V. Nutt, editors, Jan. 1974. 36. R.D. Witcofski, "Potentialand Problems of H2-fueled Supersonic and Hypersonic Aircraft," in Seventh Intersoc. Energy Convers. Engrg. Conf., San Diego, Calif., Sept. 25-29, 1972, American Chemical Society, Washington, D.C., 1972, p 1349. 37. L.O. Williams, "The Cleaning of America," Astronaut. Aeronaut. 10, No. 2, 42 (1972). 38. M. Bever, "Material Problems in the Transport and Storage of Hydrogen," E.E. Hucke, editor. Preliminary Reports, Memoranda and Technical Notes of the Materials Research Council Summer Conference, La Jolla, Calif., Vol. 1 p 492, July 1973, ARPA Order 2341. 39. Metals Handbook, 8th ed., vol. 1., T. Lyman, editor, American Society for Metals, Novelty, Ohio, pp. 599-603, 1961. 40. H.H. Johnson, "Hydrogen Embrittlement in Hydrogen and Hydrogen-Oxygen Gas Mixtures," Proc. mt. Con! on Stress Corrosion Cracking and Hydrogen Embrittlement of Iron Base Alloys, Unieux, France, June 1973, pending publication. a. C.S. Carter and H.V. Hyatt, "Review of Stress Corrosion Cracking in Low Alloy and Low Strength Steels," ibid. b. R.R. Fessler, T.P. Groeneved and A.R. Elsea, "Stress Corrosion and Hydrogen Stress Cracking in Buried Pipelines," ibid. c. R.S. Treseder, "Oil Industry Experience with Hydrogen Embrittlement and Stress Corrosion Cracking," ibid. 41. C.D. Miller, "Containment of Refrigerated and/or Compressed Gases," Proc. Conf. on Barge Transportation of Chemicals, H.H. Fawcett, editor, National Academy of Sciences, Washington, D.C., 1965, p 36. 42. H.H. West, J.R. Walker, and C.M. Sliepcevich, "Radiation, Heat Flux, and Overpressure in LNG Tanks," Conf. Proc. LNG Importation and Terminal Safety, H.H. Fawcett, editor, National Academy of Sciences, Washington, D.C., 1972, p 73. 43. D.P. Gregory and R.B. Rosenberg, "Synthetic Fuels for Transportation and National Energy Needs," Energy and the Automobile, Society of Automotive Engineers, SP-383, July 1973, p 37. 44. FAA Report to Coordinating Research Council Fuel Safety Group, Miami, Fla., Apr. 24, 1973. 32 PAGENO="0716" 710 NRL REPORT 7754 45. Jane's Fighting Ships, 1966 ed., Jane's Yearbooks, London. 46. R.V. Harris, NASA Langley Research Center, Hampton, Va., private communication, Sept. 27, 1973. 47. R.H. Miller, "Thinking Hypersonic," Astronaut. Aeronaut. 9, No. 8, 40 (Aug. 1971). 48. J.V. Becker, "Prospects for Actively Cooled Hypersonic Transports," Astronaut. Aeronaut. 9, No. 8, 32 (Aug. 1971). 49. "Hypersonic Aircraft by 2000 Pushed," Aviat. Week Space Tech. 99, No. 12, 52 (Sept 17, 1973). 50. C.W. Baulknight and E.S. Fishburne, "The Generation of High Energy Jet Fuel from Sea Water and Air Aboard a Nuclear Powered Aircraft Carrier," Grumman Aircraft Engineering Corp., contract with Naval Air Systems Command, Project 3032-012, 1970. 51. R.W. Pinnes and G.A. Russell, "A New Concept in Fuel Logistics for Naval Aircraft," U.S. Navy Bureau of Aeronautics Report NAVAER DR-1831, Oct. 1956. 52. D.P. Gregory, "The Hydrogen Economy," Sci. Am. 228, No. 1, 13 (1973). 53. D.R. Cloyd and W.J. Murphy, "Handling Hazardous Materials," Technology Survey, NASA SP-5032, Sept. 1965. 54. Chemical Propulsion Information Agency, "Liquid Propellant Handling, Storage, and Transportation," Hazards of Chemical Rockets and Propellants Handbook, Vol. III, CPIA/194, Applied Physics Laboratory, Johns Hopkins University, Silver Spring, Md., May 1972. 55. H.F. Coward and G.W. Jones, "Limits of Flammability of Gases and Vapors," U.S. Bur. Mines Bull. 503 (1952). 56. American Institute of Physics Handbook, 2nd ed., McGraw-Hill, New York, 1963. 57. M.G. Zabetakis, "Flammability Characteristics of Combustible Gases and Vapors," U.S. Bur. Mines Bull. 627 (1965). 58. NFPA Fire Protection Handbook, 13th ed., sec. 6, chap. 3 National Fire Protection Association, Boston, 1969. 59. H.C. Barnett and R.R. Hibbard, "Basic Considerations in the Combustion of Hydrocarbon Fuels with Air," National Advisory Committee on Aeronautics, Report 1300, 1957. 60. Handbook of Industrial Loss Prevention, Factory Mutual Engineering Division, Norwood, Mass., 1959. 61. C. Slack and D.W. Woodhead, "Correlation of Ignitabiities of Gases and Vapours by a Break Spark and at a Flange Gap," Proc. lEE, 113, 297 (1966). 62. IL. Drell and F.E. Belles, "Survey of Hydrogen Combustion Properties," National Advisory Committee on Aeronautics, Report 1383, 1958. 63. D.J. McCracken, "Hydrocarbon Combustion and Physical Properties," U.S. Army Ballistics Research Laboratory Report 1496, Aberdeen, Md., Sept. 1970. 64. B. Lewis and G. von Elbe, Combustion, Flames and Explosions of Gases, 2d ed., Academic Press, New York, 1961. 33 PAGENO="0717" ?:11 CARHART, AFFENS, BOSS, HAZLErF, AND SCHULDINER 65. NFPA Manual of Hazardous Chemical Reactions, National Fire Protection Association, NFPA No. 491M, Boston, 1966. 66. A. Fern, "Better Marks on Pollution for the SST," Astronaut, and Aeronaut. 10, No. 7, 37 (July 1972). 67. A. Fern, "Reduction of NO FOrmation by Premixing," New York University, AA-73-02 (Feb. 1973). 34 PAGENO="0718" 712 ME-RT-74011 UNCLASSIFIED HYDROGEN AS A FUEL R.F. McAlevy, III R.B. Cole J.W. Hollenberg L. Kurylko R.S. Rages K.H. Wail August 1974 Semi-Annual Technical Report Contract No. N00014-67-A-02O2-0046 PAGENO="0719" 713 r~rc~ National Technical Information Service Weekly Government Abstracts Technical report summaries for science, technology, business, and federal, state, and local governments December 16, 1974 -Highlight- Hydrogen as a Fuel. R. F. McAlevy, III, R. B. Cole, J. W. Hollenberg, L. Kurylko, and R. S. Magee. Stevens Inst of Tech Hoboken N J Dept of Mechanical Engineering 31 Aug 74, 238p ME-RT-740l1 AD.787 484/5WE PC$7.50/MF$2.25 An engineering study of the technical problems expected with the large-scale introduction of hydrogen (H2) as a fuel has been initiated. Information was gathered and evaluated regard- ing H2 generation, transportation and utilization as an engine fuel. H2 generation by coal gasification, electrolysis and ther- mochemical processes using nuclear heat sources was in- vestigated. Although `embrittlement' by H2 might weaken the pipeline itself, the principal problem expected in this mode of transmission appears to lie with existing compressors. A novel regenerative', compressor is discussed in this regard. Funda- mental relationships between fuel properties and reciprocating engine performance parameters are established and form a ra- tional basis for evaluating H2 (vs. gasoline) as a fuel. An ex- tensive review of published results revealed that H2 was capa- ble of highly efficient, low polluting operation of such engines when fuel-lean mixtures were used. (Modified author abstract) Energy - WGAI97-74/5O PAGENO="0720" 714 Semi-Annual. Technical Report (for the Period: 74 January 01 to 74 June 30) Title: Contract Number: Effective Date: Expiration Date: Amount: Date: Principal Investigator: Scientific Officer: Hydrogen as a Fuel N000l4-67-A--202-0046 74 January 01 74 September 30 $ 130,000.00 74 Aucust 31 Dr. Robert F. 201-792-2700, Ext. Director, Power Programs Materials Sciences Division ONR, Department of the Navy 800 North Quincy Street Arlington, Virginia 22217 Sponsored by Advanced Research Projects Agency ARPA Order No. 2615 Program Code 4FlO Form Approved - Budget Bureau : No. 22-R0293" PAGENO="0721" 715 Table of Contents Abstract 1 Introduction 2 Technical Summary 4 Appendix A - Hydrogen Production A-i Appendix B - Hydrogen Pipeline Transmission B-i Appendix C - Hydrogen Fueled Engines C-i DD Form 1473 Distribution List 62-332 0 - `76 - 46 PAGENO="0722" 716 ABSTRACT An engineering study of the technical problems expected with the large-scale introduction of hydrogen (H2) as a fuel has been initiated. During the subject six-month period in- formation was gathered and evaluated regarding H2- generation, transportation and utilization as an engine fuel, and are reported. Results and conclusions are tentative and subject to future revision. ~2 generation by coal gasification, electrolysis and thermochemical processes using nuclear heat sources was investigated. In this country despite the extensive coal reserves, the proven, commercially-viable gasification is not used, although some newer processes might have an impact in 5 years or so. Electrolytic generation theoretically takes place at high efficiency, and a number of competitive designs to reach this goal are evaluated. The thermochemical approach becomes more feasible at the nuclear core coolant temperature increases, fast-breeder reactors probably cantt be used but high-temperature gas-cooled reactors can. Although "embrittlememt' by H2 might weaken the pipeline itself, the principal problem expected in this mode of trans- mission appears to lie with existing compressors. A novel, `regenerative, compressor is discussed in this regard. Fundamental relationships between fuel properties and reciprocating engine performance parameters are established and form a rational basis for evaluating H2 (vs. gasoline) as a fuel. An extensive review of published results revealed that H2 was capable of highly efficient, low polluting operation of such engines when fuel-lean mixtures were used. -1- PAGENO="0723" 717 INTRODUCTION This the First Semi-Annual Technical Report on Contract No. N00014-67-A-0202-0046 entitled, "Hydrogen as a Fuel'. The intention of the program is to make an engineering study of hydrogen as a fuel, including its generation, storage, trans- portation, safety and utilization, especially the technical problems likely to arise with the introduction of hydrogen (H2) on a large scale. During this first 6 month period a variety of topics were studied. However, only those in which sufficient progress was made to warrant reporting are included herein. Any conclusions that are drawn as a result of this initial activity must be considered preliminary and subject to change. The entire technical content of this report is organized into Appendices which are intended to be independent and com- plete in themselves. The technologies examined in each appendix are at different stages of development. Consequently, the approach to and treatment of these technologies varies from appendix to appendix. ~p~endix A- Hydrogen Production deals with three means of H2 production: "Hydrogen. Production by Electrolysis";"Production of Hydrogen by Coal Gasification" and "Thermochemical Hydrogen Pro- duction". The first was prepared by D.P. Gregory and A.J. Konopka of the Institute of Gas Technology under a subcontract;it is an evalu- ation of the potential of various high-efficiency electrolytic tech- niques for H2 production. The second was prepared by L. Kurylko; it deals with means of producing H2 by coal gasification. The third was pre- pared by R.S. Magee; it is an evaluation.of .the potential of H2 pro- duction by thermochemical processes employing nuclear heat sources. Appendix B-Hydrogen Pipeline Transmission was prepared by J. W. Hollenberg. It deals with the technical problems to be considered if gaseous H2 is transmitted by pipelines, especially the problems related to the compressors that are used to boost the pressure at various stations along the pipeline. -2- PAGENO="0724" 718 Appexdix C - Hydrogen-Fueled Engines was prepared by R.B.Cole and R.F. McAlevy,III. It deals primarily with reciprocating, spark-ignition engines and is an evaluatiOn of }12-fueled (and gasoline-fueled) operating experience on a fundamental basis, provided by relationships between engine performance and fuel properties. -3- PAGENO="0725" 719 TECHNICAL SUMMARY The purpose of the subject program is to conduct an engi- neering study of the technical problems to be expected with the large-scale introduction of hydrogen (H2) as a fuel and to recommend means for their solution. The areas of concern are H2 production, storage, transportation, safety and utili- zation. The work reported herein was directed towards def i- nition of the technical problems; it deals with current status of technology and/or ultimate potential depending on subject area. To date, storage and safety have received insufficient attention to be reported upon. The general methodology involved was literature review, plant and laboratory visitation, technical meeting attendance, and telephone and written communication. All of the technical content of this report is contained in the three appendices which are each complete and independent. That is, each could be considered a separate report covering certain aspects of (a) generation; (b) transportation and (c) utilization. Each appendix contains its own abstract and summary. The results and conclusions that emerged from the subject six month initiation period must be considered preliminary and subject to future revision during further study. Appendix A --Hydrogen Production deals with H2 generation by electrolysis, coal gasification and thermochemical processes. Highly efficient electrolyzers are required if large-scale electrolysis of H2 is to be economically feasible, owing to the ever-increasing cost of electricity. An analytical expression for electrolyzer efficiency is presented and the conditions re- quired for maximum efficiency are discussed. A review of current technology reveals that much of the present effort in electrolyzer design is directed toward achieving the high levels of efficiency that are theoretically possible. Eased on the information avail- -4- PAGENO="0726" 720 able, however, it was impossibl~ at this time to discern one that is universally superior. Coal gasification appears pract1~cal for near-term and intermediate-term H2 generation in the U.S.A. because of this country's large coal reserves and the growing world-wide shortage of petroleum. Two proven processes are already in commercial use in other countries, the Lurgi process and the Koppers-Totzek process (the latter being preferred for high H2 yields). However, neither process is currently used in this country. Instead, H2 is generally produced by steam re- forming of natural gas and petroleum liquids, apparently as a result of economic constraints. Coal gasification processes will have no significant impact on H2 generation in this country for 5 years or so. In the long tern, H2 generation by thermochemical water- splitting processes appears promising, using nuclear heat sources. For the chemical processes proposed to date sufficient funds- mental information does not exist to permit selection of the most promising candidates. Generally, the thermochemical pro- cesses involve fewer reactions and higher efficiencies the higher the maximum temperature at which heat is available. Thus, the thermo- chemical H2 generation will be feasible with high-temperature gas-cooled reactors (temperature of coolant between about 800°C and 1000°C) and probably is not feasible with the liquid metal fast-breeder reactor (coolant temperature between about 450°C and 575°C). Appendix B - Hydrogen Pipeline Transmission, reviews this country's natural-gas transmission system in light of its po- tential use for gaseous H2 transmission. Despite suggestions by others that pipelines could be weakened by H2 "embrittlement", a 130 mile, 12" diameter pipeline has been in continuous H2 ser- vice in Germany since 1938; H2 is introduced at 600 psia and de- livered at a minimum of 225 psia. It has no compressors, operat- ing by "blo~down'. Thus, there is no experience with H2 pipeline compressors. The `regenerative" compressor is proposed for this -5- PAGENO="0727" 721 pu1~pose, and its operation ahd historical development are dis- cussed in some detail. Appendix C - Hydrogen-Fueled Engines deals with funda- mental relationships derived between fuel properties and engine-performance parameters; operating experiences with H2 fueled, reciprocating, spark-ignition engines are also compre- hensively summarized. Together, these provide a rational basis for evaluation of H2 as a fuel. Numerous comparisons are made between H2 and gasoline use; it is shown that H2 operation allows high efficiency and low pollutant emissions along with a control possibility (`quality control") which is impractical with gasoline. However, to gain these advantages of H2 opera- tion, engines must be operated fuel-lean at, say, half the stoichiometrically correct `fuel/air mixture ratio. Under such conditions, the chemical-energy content of the lean fuel/air mixture is reduced, substantially penalizing the work (or power) output of the engine. Conventional supercharging or cylinder fuel injection can compensate for such a power penalty while maintaining the advantages of H2 use. From many viewpoints, H2 is an attractive alternative to gasoline and other hydrocarbons as engine fuels. Hydrogen use deserves further investigation both experimentally and analytically. -6- PAGENO="0728" 722 APPENDIX A - HYDROGEN PRODUCTION ABSTRACT Rydrogeri productIon by electrolysis, coal gasification, and thermochemical decomposition of water was investigated in an attempt to determine the current status of technology, ultimate potential and inherent technological problems associ- ated with these approaches. Much of the current effort In electrolyzer design is dir- ected towards developing the high eUiciency potential of electrolysis. There is no single type of electrolyzer that is universally held as superior. It appears that the yarious design philosophies could result in hydrogen generation techniques quite different in concept from each other, yet all of industrial significance in appropriate applications. Coal remains the fossil fuel of the future. There are two major processes of coal gasification currently used com- mercially: the Lurgi process and the Kdppers-Totzek process. None of these processes are currently used in the United States but are well proven in many installations worldwide. The Koppers- Totzek process is currently the preferred gasification process in applications when only hydrogen is required. New processes of coal gasification are not expected to make substantial changes in the presently used coal gasification techniques within the next five years. `It was concluded that hydrogen production by thermochemical processes employing nuclear heat sources has excellent potential to meet future hydrogen demands. However, since the majority of thermochemical cycles proposed to date are only in the early stages of development, extensive research, and development will be required to advance currently proposed processes to commercial practice. A-i PAGENO="0729" 723 APPENDIX A - HYDROGEN PRODUCTION Page A.l - BACKGROUND AND INTRODUCTION A-i A.i.l - General A-i A.i.2 - References A-2 A.2 - HYDROGEN PRODUCTION BY ELECTROLYSIS A-3 A.2.l - Introduction A-4 A.2.2 - Theory of Electrolysis A-6 A.2.2.l - Effectof Pressure on Decomposition Voitage A-9 A.2.3 - Factors Affecting Electrolyzer Design A-li A.2.3.i - Operating Parameters A-li A.2.3.2 - Electrodes A-14 A.2.3.3 - Diaphragms or Cell Separators A-15 A.2.4 - Types of Electrolyzers - Current Status of Technology A-l7 A.2.4.l - Tank Electrolyzer A-l7 A.2.4.2 - Filter-Press Electrolyzer A-20 A.2.4.3 - Stuart Cell A-2l A.2.4.4 - Teledyne Electra Cell A-24 A.2.4.5 - General Electric Solid Polymer Electrolyte Cell A-3l A.2.4.6 - Life Systems Cell A-34 A.2.4.7 - Lurgi High-Pressure Cell A-38 A.2.4.8 - Cominco Cell A-40 A.2.4.9 - DeNora Electrolyzer A4l A.2.5 - Comparative Evaluation of Various Electrolyzers A-43 A.2.6 - Ultimate Potential A-46 A.2.7 - Research and Development Requirements - Engineering Problems A-46 A.2.7.l - Stuart Cell A-46 A.2.7.2 - Teledyne Electra Cell A-48 A.2.7.3 - GE Solid Polymer Electrolyte A-49 A.2.7.4 - Life Systems' Cell A-52 A.2.7.5 - Acyclic Generators A-53 A.2.8 - References Cited A-55 A-u PAGENO="0730" 724 A.3 - PRODUCTION OF HYDROGEN BY COAL GASIFICATION A-58 A.3.1 - Introduction A-58 A.3.l.l - Historical Background A-58 A.3.2 - Gasification Reactions for Production of Hydrogen A-66 A.3.3 - Gas Producers A-68 A.3.4 - Lurgi Gasifiers A-il A.3.5 - Koppers-Totzek Gasification Process A-75 A.3.6 - Winkler Gasification Process A-78 A.3.7 - Other Coal Gasification Processes A-8l A.3.7.l - Hygas Coal Gasification Process A-8l A.3.7.2 - CO2-Acceptor Process for Coal Gasification A-82 A.3.7.3 - Synthane Process for Coal Gasification A-82 A.3.7.4 - Bigas Process for Coal Gasification A-85 A.3.8 - Comparison of Various Processes of Coal Gasification A-85 A3.9 - Conclusions A-89 A.3.lO- References A-96 A.4 - THERMOCHEMICAL HYDROGEN PRODUCTION A-98 A.4.l - Introduction A-98 A.4.2 - Physical Principles and Theory A-99 A.4.3 - Current Status of Technology A-l03 A.4.3.l - Halide Processes A-l03 A.4.3.2 - Reverse Deacon Processes A-108 A.4.3.3 - Metal Processes A-llO A.4.4 - Comparative Evaluation of Current Processes A-114 A.4.5 - Ultimate Potential A-ll5 A.4.6 - Research and Developnent Needs A-117 A.4.7 - References A-1l9 A.5 - SUMMARY A-121 A-ui PAGENO="0731" 725 APPENDIX A - HYDROGEN PRODUCTION A.l - BACKGROUND & INTRODUCTION A.l.1 - General Hydrogen has been discussed frequently in the recent past as a potential, highly flexible energy medium of the future. It is -ecologically attractive and broadly usable and it can be produced from a virtually inexhaustible feedstock, i.e. water. Much has already been written about the long-range potential for the `hydrogen economy" (Ref. 1,2). Perhaps the most important single factor influencing the large scale use of hydrogen resides in the production system. It must be competitive to alternate, clean energy media, both in terms of the costs and the impact on the use of resources and the environment. Present means of commercially producing hydrogen in the U.S. are by steam reforming of methane and naptha, and partial oxi- dation of fuel oil. The majority of hydrogen currently produced in Europe is also made by steam reforming of petroleum fractions. Hydrogen can also be produced by electrolytic decomposition of water, but the present higher cost of this method restricts this approach to areas such as in Canada and Norway, where hydroelectric power is abundant. Clearly, our decreasing natural gas and crude oil reserves indicate that we cannot afford to continue producing hydrogen by current practice, even to just meet the growing needs for use in ammonia production, oil refining, methanol production, etc. And for the potential of the "hydrogen economy" to be realized, hydrogen production will have to increase several fold over the current projections for the year 2000. This section discusses three options for the production of hydrogen: electrolysis, coal gasification, and thermochemical decomposition of water. While electrolysis is the best developed of these technologies at present, the cost of producing hydrogen A- 1 PAGENO="0732" 726 by electrolysis is determined largely by the cost of electricity and as such has not been economically attractive. However, the possibilities of improved electrolyzer technology coupled with lower off-peak electric costs, make this method attractive for further investigation. Our vast coal reserves, insures that this resource will be a prime source for hydrogen and other syn- thetic fuels in the future. The various proposed processes for the production of hydrogen from coal are discussed. Finally, various schemes for the production of hydrogen from thermochemi- cal decomposition of water are reviewed. Other means for the production of hydrogen, e.g., biological prąduction schemes, are not considered. It was felt that within the scope of the present program, these proposed schemes were not sufficiently developed to allow adequate analysis of their tech- nical feasibility and inherent technological problems. A.l.2 - References 1. Gregory, D.P., Ng, D.Y.C., and Long, G.M., "Electro- chemistry of Cleaner Environments J.O.'M. Bockris, Ed., Plenum Press, New York, pp. 226-279, 1972. 2. Marchetti, C., Chemical Economy and Engineering Review, Vol. 5, No. 1, pp. 7-25, 1973. A- 2 PAGENO="0733" 727 The following section entitled: A.2 Hydrogen Production by Electrolysis was prepared for Stevens Institute of Technology by D.P. Gregory and A.J. Konopka of the Institute of Gas Technology, III Center, Chicago, Ill. 60616. A-3 PAGENO="0734" 728 A.2 - HYDROGEN PRODUCTION BY ELECTROLYSIS A.2.l Introduction Electrolytic production of hydrogen is the simplest and cleanest method for making hydrogen from water. An electrolytic cell operates with essentially no moving parts, can be designed to produce no by- products, and offers the physical separation of hydrogen and oxygen as well as the initial decomposition of water. In principle, cells can be operated at high pressure with no efficiency penalty, so that electrolysis also represents the most energy-conservative means of developing pres- sure in the hydrogen product. Several large electrolytic hydrogen plants, consuming upward of 100 MW, have been constructed and have operated successfully, while many thousands of smaller units are in use for special applications. However, electrolysis is not a major process for hydrogen production and is normally considered to be expensive and inefficient. Why is there a reluctance to use electrolysis as a major hydrogen- producing process? Basically, because its prirńary energy source, electric power, is expensive and is only obtained at low efficiency frcm other energy sources. The electrolytic process itself is normally oper- ated at efficiencies in the 60-75% range and at capital costs only a fraction (about one-fifth to one-third) of the cost of the power station needed to drive it. Because electrolytic-hydrogen costs are dominated by electric-power costs, large electrolysis plants are located only where there is an abundance of cheap hydroelectric power. These plants have been optimized for low capital costs and normally operate at efficiencies lower than can readily be achieved in practice. As power costs increase, more effort must be expended to develop the high efficiency potential of electrolysis. In the course of this study, we have drawn on published information, on trade literature, and on personal interviews with representatives of Electrolyser Corporation, Teledyne Isotopes, General Electric Company, Life Systems, Inc., and De Nora S. p. A., whose assistance we gratefully acknowledge. It is clear that the manufacturers of electrolyzer plants are in an industrially competitive business and are therefore not free to divulge proprietary information. It is also clear that various people and companies have considerably diverging opinions on the most favorable design concepts and technical approaches for electrolyzer construction, and that there is no single type of electrolyzer that is universally held as superior. PAGENO="0735" - 729 Because electrolyzers can be operated over a range of voltages and current densities, no hard figures can be quoted for efficiency of pperation or for capital costs. Each system must be designed and operated accord- ing to its specific application, and no competitive manufacturer will willingly disclose such figures publicly. The economics of electrolytic hydrogen production are therefore extremely hard to come by and must be inter- preted with care. We wish to stress in this report that the electrolytic production of hydrogen is an already achieved commercial process that can no doubt be improved considerably, both in capital cost requirements and in energy efficiency, by appropriate research. Although electrolysis is not today's major source of hydrogen, the technology involved in many other large- scale electrochemical production processes is appropriate to much of the overall system design of an electrolysis plant. The entire world production of aluminum results from electrolytic plants, as does most of the current production of such heavy chemicals as chlorine, caustic soda, hydrogen peroxide, and several metals including copper, zinc, and nickel. Thus, electrochemical production is not a new and untried con- cept in industry, and the electrolysis of water is a process capable of the massive scale-up that would be needed if hydrogen became a signif- icant fuel or energy carrier. Three factors dominate the usefulness of an electrochemical cell for hydrogen production. One is the energy efficiency, related to the cell's operating voltage; another is the capital cost of the plant, related to the rate of hydrogen production from a cell of a given size. These two factors are closely interrelated. The third factor is the lifetime of the cell and its maintenance requirements, which involve the materials used in its construction and the operating conditions selected. In this report we will emphasize an analysis of these three factors, howthey relate to each other and to current technology, and what needs to be done to improve them. A-5 PAGENO="0736" 730 A. 2.2 Theory of Electrolysis If two electrodes are placed in water, hydrogen ions produced by self-ionization migrate toward the negative electrode - the cathode - and hydroxyl ions to the positive electrode - the anode.' Because water has a low ionization constant, it displays a relatively high electric resistance. Both the hydrogen and hydroxyl ions have very high mobilities, which provide low electric resistances. As a result, strong aqueous acid or alkali solutions are suitable ionic-transport media for electrolysis cells. Other electrolytes are not normally considered for use in cells because they, themselves, break down under electrolysis and yield undesirable by-products. Because of very severe corrosion problems encountered in the electrolysis of acids, present state-of-the-art industrial electrolyzers almost universally use low-concentration aqueous potassium hydroxide or sodium hydroxide. The overall reaction for the decomposition of water is given by - H20(L) -. llz(g) + `I~z(g) This reaction can be broken down into the reactions at the anode and cathode. At the anode, hydroxyl ions are discharged and form oxygen. The metal or metal oxide surface of the electrode enters into the reaction according to a proposed mechanism' that can be represented as follows: 0H + M'O M'O - 0 + H+ + 2e ZM'O - 0 2M'O + Oz M' represents the metal surface of the anode, which is usually nickel or cobalt. At the cathode, the water molecule is discharged on a metal surface according to the reaction 2M2 + 2H20 + 2e 2M' - H + 20H 2M2_H~Hz+2MZ A-6 PAGENO="0737" 731 M2 represents the surface of the cathode, which is usually iron. The participation of the metal surface in anode and cathode reactions is im- portant; changing the nature of the metal can profoundly affect the catalysis of the electrode reactions. The overall process of water decomposition by electrolysis is the reverse of the combustion of hydrogen. Therefore, the theoretical amount of energy required per unit quantity of hydrogen produced is the same as the heat of combustion. Each hydrogen molecule is formed by the addition of two electrons to two hydrogen ions in solution, so that a direct relationship exists between the current passed (electron flow rate) and rate of hydrogen production (Faraday's law). Deviations from Faraday's law, which implies that 15. 6 SCF* of hydrogen is produced per 1000 A-hr, is characterized by the electric current efficiency of the cell. The current efficiency in most cells approaches 100%. Any lower efficiencies experienced are the result of extraneous electrode reactions during the electrolysis, but theoretically, no alternative chemical reactions can occur except the recombination of hydrogen and oxygen in solution. A perfectly efficient cell would require 94 kWhr of electrical energy for each 1000 SCF of hydrogen produced. Of these 94 kWhr, only 79 need to be supplied as electrical energy; the remainder as heat. Since this energy input to the cell is in the form of power, the product of voltage and current, each electrolytic process has a theoretical voltage corres- ponding to the energy required for the reaction to proceed. In electrolysis only the free energy of reaction, ~G, can be inter- changed with electrical energy at constant temperature and pressure. The quantity of electric charge corresponding to the molar quantities indicated in the balanced chemical equation is nF, where n is the number of elec- trons transferred per molecule and F is the Faraday value. If this quantity of electrical charge is transported through a potential difference of E volts, the amount of work required is given by nFE. 2 Since this electrical change does not involve pressure-volume work and is carried out iso- thermally, the change in Gibbs free energy is given by - * All cubic feet measurements given in this Appendix are at standard conditions, 68°F and 14. 7 psi. A-7 62-332 0 - 76 - 47 PAGENO="0738" 732 ~G=-nFE (1) where E is the potential difference or voltage, which by convention is taken as positive. Since i~G is negative for a spontaneous cell reaction, and E for a spontaneously discharging cell is taken as positive, there results a negative sign in Equation 1. The electromptive force of a cell does not depend on the stoichiometric coefficient in the balanced chemical reaction, but the change in Gibbs free energy ~G does depend on n, which in turn depends on how the chemical equation is written. 2 The entropy change for an electrolytic cell reaction may be calculated from the temperature coefficient of the electromotive force since - -~s ~T~p Introducing this into Equation I, we have2 - nF(-~-~)~ = ~S (2) The enthalpy change for the cell reaction may be calculated by substituting Equations 1 and 2 into - - = i~G + T~S = -nFE + nFT(-~-~)~ (3) It is apparent from Equation 3 that the difference between free energy change and the total energy change (enthalpy) is accounted for by a change of entropy in the process. Since the entropy change cannot be converted to electricity, it must be supplied or liberated as heat. We can calculate that for a water electrolysis cell the voltage cor- responding to the enthalpy change, or heat of combustion of hydrogen, is 1.47 V at 25°C (77°F), whereas the cell voltage corresponding to the free energy change is only 1.23 V. This difference is important because ~ factor that works in favor of electrblyzers and against fuel cells. In an ideal case, then, a voltage of 1.47 V applied to a water electrolysis cell at 25°C (77°F) would generate hydrogen and oxygen iso- thermally - that is, at 100% thermal efficiency with no waste heat pro- duced. However, a voltage as low as 1. 23 V would still generate hydrogen and oxygen, but the cell would absorb heat from its surroundings. The electrical energy required for the process is only 83. 7% of the combustion A-8 PAGENO="0739" 733 combustion energy of the hydrogen produced, the other 16.3% being supplied as heat. Another way of expressing this is that the fuel value of the hydrogen produced is 120% of the heating value of the electrical energy put in.7 In marked contrast to a hydrogen fuel cell, therefore, we see that under ideal conditions a water electrolyzer can have a theoretical thermal efficiency of up to 120%, while a perfect fuel cell is limited to an "electrical" efficiency no greater than 83. 5%, if it operates at 25°C (77°F). ~ The free energy change voltage, or "reversible" voltage as it is called, varies with temperature, as shown in Figure A. 2-1. We can see that raising the temperature lowers the voltage at which water can be decomposed. Again, this factor operates in favor of electrolysis cells because at higher temperatures the electrode processes proceed faster, with lower losses, while the required energy input is less. This is in contrast to fuel cells; their available energy output falls as the temperature is raised.7 The voltage corresponding to enthalpy change, or, as we shall term it, the `thermoneutral voltage" varies only slightly with temperature, from 1.47 Vat 25°C (77°F) to 1.50 Vat 340°C (644°F). This is also shown in the figure. We can therefore identify three areas in which 1) no hydrogen is evolved, 2) hydrogen is made at an apparently greater-than-l00% efficiency, and 3) hydrogen is made at less than 100% efficiency with production of waste heat. A. 2. 2. 1 Effect of Pressure on Decomposition Voltag~ Considering the theoretical aspects of the effect of pressure on electrolysis, we have to inquire into the effect of pressure upon the decomposition voltage, the conductivity of the electrolyte, overvoltage of the electrodes, and concentration polarization. In the ideal case - obviously, a cell made up of a hydrogen and oxygen gas electrode - the electromotive force will be equal to the reversible decomposition voltage. The variation in the potential of a gas electrode with pressure is given by Helmholt~! equation17 - E= Eo+~lnf (4) A-9 PAGENO="0740" 734 Figure A. 2. 1: `IDEALIZED OPERATING CONDITIONS FOR ELECTROLYZER4 where Eo and E are the potentials at the pressures Po and P and RT P. in ~- is the increment of potential due to a change of pressure (P - Po). By the usual convention, the Eo for a hydrogen electrode at atmospheric pressure is zero - 0. 0577 E - logioP and at all pressures log~oP for a given gas electrode should be constant. The effect of pressure on conductivity of the electrolyte can be ex- pressed by the following equation - 1 ~X 1 ~V 1 ~n 1 ~a 3:* ~-p-v* ~ -~-p-+~* ~ 400 500 TEMPERATURE,'F A81940 A-10 PAGENO="0741" 735 Any change in the conductivity (X) of an electrolyte implies a change in the number ~of ions and their mobility. This can only be brought about by altering the degree of dissociation of the electrolyte (a), its specific volume or compressibility, and/or its viscosity (n). The conductivity (X) and the volume (V) of the electrolyte are both measured at atmospheric pres sure. A. 2. 3 Factors Affecting Electrolyzer Design A.2.3. 1 O~perating Parameters The theoretical decomposition voltage of water, calculated by thermo- dynamic laws, is 1.23 Vat atmospheric pressure and 77°F. A voltage above the theoretical value is necessary for the decomposition reaction to occur at a discernible rate. This excess voltage above the decompo- sition voltage is usually referred to as "overvoltage." The overvoltage is made up of three principal components. One is the ohmic resistance of the electrolyte itself, another originates at the hydrogen-evolving electrode, and the third is associated with the oxygen- evolving electrode. Hydrogen overvoltage, then, is defined as the difference in potential between a hydrogen electrode at equilibrium and a hydrogen electrode subjected to cathodic current flow in the same electrolyte. Similarly, oxygen overvoltage is defined as the difference in potential between an oxygen electrode at equilibrium and one being anodized with an external current. Thus, the expression "overpotential" is sometimes used,instead of overvoltage or polarization,for individual electrodes. The amount of total cell overvoltage above the theoretical value of 1.23 V is de- pendent on the electrode construction and materials, the electrolyte resistance, and the amount and kind of foreign ions in solution. The energy efficiency of an electrolyzer can be measured by comparing its operating voltage with the theoretical value. The higher the applied voltage, the higher will be the rate of reaction, which produces a higher current. For most industrial electrolyzers, operating voltages in the range of 1. 7-2. 2 V per cell are necessary to decompose water. A-li PAGENO="0742" 736 In a comparison of various electrolyzer concepts, it is difficult to include all the factors that influence operating cost and efficiency. The designer of an electrolyzer will custom-design his unit to fit the exact conditions prevailing at the user's premises, so that two seemingly iden- tical units from the same manufacturer may be operated under quite different conditions. Because the current efficiency of most electrolyzers is almost 100%, the overall energy efficiency of hydrogen production is largely a matter of the operating voltage. We shall refer to the "thermal efficiency of electrolysis as the cell potential corresponding to thermoneutral operation [1.47 V at Z5°C (77°F), 1 atmJ divided by the actual operating voltage. This corresponds to the ratio of the high heating value of the hydrogen produced to the electrical energy input. It is possible to operate a given electrolysis cell over a wide range of voltages or efficiencies, with a corresponding variation in current. An electrolysis cell has a specific current-voltage characteristic; *the cell operates somewhat as a nonlinear resistor. As greater voltages are applied to the cell, greater rates of hydrogen production are achieved by sacrificing energy efficiency. The amount of current flowing per unit area, or the current density at which a cell operates, determines the rate of hydrogen produced per unit area of electrode and is therefore an important factor in determining the unit cost of equipment for a given rate of production. Both the effi- ciency and unit cost can be changed by simply altering the operating conditions of the cell. Thus, there are tradeoffs among a) the operating voltage (efficiency), b) the rate of hydrogen production (current), and c) capital cost, all of which depend on the individual current-voltage characteristic of each type of electrolyzer. Selection of the optimum operating conditions for a specific installation depends markedly on the cost of electric power at that location. Although the efficiency of operation can be adjusted during the life of an electrolyzer cell simply by altering the current and voltage at which it operates, such modifications will have a large effect on the output rate. Thus, the designer prefers to anticipate future changes in electric power costs by designing equipment to which additions can be made, if necessary, to keep production rates constant while the efficiency is raised. A-12 PAGENO="0743" 737 Changes in electrolyte pH or concentration will naturally shift the reversible hydrogen potential. Since overvoltage is defined here as the difference in potential between the reversible electrode and the working electrode in the same solution, at the same pressure, and at the same temperature, the overvoltage must be expressed with respect to a re- versible electrode subjected to the same conditions as the working elec- trode. If this definition of overvoltage is used, one observes in many metals the following dependence on pH: The overvoltage first increases with increasing pH, and then de~reases again in alkaline solution. The maximum overvoltage is observed at about pH 8. It is pointed out in the Encyclopedia of Electrochemistry9 that this variation of overvoltage with pH is surprisingly small considering that the concentration of the reacting species changes by many orders of magnitude. The effect of increasing temperature in an electrolysis cell is to reduce the cell's operating voltage for two distinct reasons. One is because the electrode processes are speeded up at higher temperatures, which results in a lowering of the overpotentials at both electrodes. This is a true gain in efficiency of operation. The other is due to the reduc- tion in the theoretical reversible potential for the cell at higher temper- atures. However, as shown in Figure 1, the total enthalpy change of the reaction, shown by the "thermoneutral" voltage line, actually increases with temperature, so that even if the electric voltage is reduced, a correspondingly greater amount of energy is required to be supplied as heat. Overall, there is a net advantage in operating efficiency to be obtained by increasing cell temperatures, but this is offset by increased corrosion rates of the electrodes and the separator materials. A number of advantages can be gained from operating an electrolyzer at higher pressures, including a) a reduction in specific power consump- tion, b) delivery of gas at pressure thus reducing or eliminating the cost of gas compressors, and c) reduction in the size of electrolysis cells.' It was shown in the previous section that the reversible cell voltage in- creases with pressure. However, the decrease in volume of the gases and the higher operating pressures result in a reduction in electrode overpotential, and there is usually a small overall reduction in the cell voltage. This real gain in efficiency is offset by increases in the costs of pressure vessels or stronger components. A-13 PAGENO="0744" 738 A.2.3.2 Electrodes To increase the operating efficiency, operating voltages can be lowered for a given current by using electrodes that carry precious-metal catalysts or that incorporate sophisticated metallurgical structures, both of which are expensive. The purpose of these sophisticated structures is principally to increase the actual physical surface area of the electrode without increasing the overall size of the cell. A roughened surface or a porous electrode with a high internal surface will achieve this objective. The purpose of a catalyst is to speed up the electrode reaction at the surface itself. Some electrodes incorporate both approaches, applying a catalyst to a highly developed surface. When such expensive electrodes are used, the cell must operate at higher current densities, so that the capital cost per unit of hydrogen production does not rise beyond the economic limits. As current densities are increased, higher voltages are needed, and the gain, to some extent, is canceled. Thus, it is not an easy matter to compare the relative merits of a system that operates, for example, at 1.8 V and 100 A/sq ft of electrode with another that operates at Z.O V at 100 A/sq ft unless the component costs are known and unless the importance of energy efficiency over capital costs is clearly defined. Overvoltage and current density are empirically related. The de- pendence was first described quantitatively by Tafel in 1905 by the equation9 - n = a + b log I where i is the current density (total current divided by the absolute surface area of the electrode structure), n is the overvoltage, and a and b are constants that are dependent on temperature, surface state, and materials. Tafel lines, characterized by the above equation, are available for different materials and can be used as a reference in electrolyzer design, but the development of a high area surface, so as to reduce i, frequently dominates the variation in a and b due to material choice. A-14 PAGENO="0745" 739 The influence of electrode material on overvoltage and the catalytic ability of certain metals to recombine hydrogen atoms was discovered by Bonhaeffer in l924.~ Both electrolytic hydrogen evolution and the catalytic recombination of hydrogen atoms depend on their energy of ad- sorption. It has been demonstrated that the hydrogen overvoltage, in general, decreases with increasing heat of adsorption. The adsorption energy, in turn, can be related to the cohesion energy, or sublimation energy, of the metals, and these, in turn, to electron concentration, surface energy, interatomic distance, compressibility, melting point, and electronic work function. Electrochemical interfaces contain species other than protons and discharged hydrogen atoms. In particular, certain metals show a very strong affinity for water or oxygen, in fact, so strong that these metals cannot be plated out from aqueous solution. The discharge of hydrogen on such metal surfaces as molybdenum, tantalum, tungsten, zinc, niobium, chromium, and manganese proceeds with relative difficulty because of the strong affinity of oxygen for the surface. Cathodic polarization may not remove the oxide films or adsorbed oxygen species completely. The discharge of hydrogen gas will then take place on partially oxidized sur- faces. Because the effect of the high adsorption energy of hydrogen on these metals is obscured by the strong affinity for oxygen, hydrogen overvoltage thus depends on the relative adsorption energy of protons and foreign species.9 A.2.3.3 Diaphragms or Cell Separators The purpose of a diaphragm is to prevent adjacent electrodes from coming into electronic contact and to prevent the passage of gas from one electrode compartment to another without offering an appreciable resis- tance to the passage of current within the electrolyte. Gases might pass through the diaphragm between the compartments either as small bubbles or as dissolved gas, which would lead to a decrease in current efficiency and possibly to explosions. Dissolved-gas crossover is serious only in pressure operations, where the solubilities of the gases in the electrolyte are considerable. To prevent the passage of gas bubbles, the diaphragm must consist of small pores whose capillary. pressure is greater than the maximum differential pressure applied across the cell. A-15 PAGENO="0746" 740 If the diaphragm is not wetted by the electrolyte, the gas will collect preferentially in the pores, leading to an increase in resistance and even- tually to the passage of gas. To prevent the passage of dissolved gas, for example, in pressure operation, the diaphragm must offer considerable resistance to flow of the electrolyte but, - of course, a low resistance to current. These requirements are not as incompatible as they might ap- pear because the electrolyte resistance will vary approximately as the reciprocal of the voidage or porosity of the diaphragm. The resistance to flow will depend on the actual size of the pores, the flow rate decreas- ing as the pore size is reduced. Asbestos is the most common material used for diaphragms.' Electrolyzers operating at atmospheric pressure uae woven asbestos cloth as diaphragms. Sometimes fine nickel wire is used to support the structure. Pressure electrolyzers usually have a mat or felt of asbestos fibers which produäes a fine pore structure, giving a higher resistance to the penetration of gases. This mat is usually supported by the electrodes or by some other means. Work is being carried out at DuPont and other organizations to improve and design new diaphragm materials.'6 The cost of improved diaphragms will be higher than for those made of asbestos. However, im- portant savings in power consumption and cell maintenance appear possible. In the process of designing electrolysis cells, certain important design features must be considered,which are enumerated here for gen- eral information": 1. Thermodynamic properties such as heats of formation, free energies of formation, specific heats, activities, standard electromotive poten- tials, and reduction of these to the desired environment of electrolysis and equilibrium constants 2. Solubilities, composition_temperature diagrams, vapor pressures, and specific gravities of mixtures of electrolyte, water, hydrogen, and oxygen 3. Electrical conductivities of electrolytes versus concentration and temperature; conductivities of all current-carrying cell materials and electrodes A-16 PAGENO="0747" 741 4. Polarization data and overvoltage versus current density for various electrolyte concentrations, temperatures, pressures, and electrode materials. The latter may be affected by various surface treatments, orientation and age of the electrodes, and trace impurities in the electrolyte. 5. Effect of gas bubbles (increase in cell resistance) and other suspensions on the conductivity of the electrolyte. As the current density or hydrogen-generation rate is increased, more gas bubbles are produced. The influence of gas bubbles can be reduced by optimum spacing of the electrodes or by the use of perforated electrodes, so that the gases escape from between them, or by operating the cell under pressure so the actual volume of the gas generated is reduced. 6. Diaphragm (electrode separator) properties including permeability, porosity, and relative resistivity. 7. Diffusion coefficients for atoms near electrode surfaces, both porous and nonporous 8. Thermal conductivities, heat-transfer coefficients, fluid properties, and viscosities for electrolytes and cell materials. Recent sophisti- cated studies have been carried out on fluid flow and heat transfer in water electrolyzers by Thorpe and Funk.3° 9. Corrosion rates of materials of construction. These are affected seriously by the potential at which the material is operated, and are thus sensitive to the current density of operation. The temperature of operation is also a serious factor in determining corrosion rates. A. Z. 4 ~ypes of Electrolyzers - Current Status of Technolo~gy A.2.4.l Tank Electrolyzer The oldest form of industrial electrolysis of water uses the tank electrolyzer,24 in which a series of electrodes, anodes and cathodes alternately, are suspended vertically and parallel to one another in a tank partially filled, most commonly, with a 20-30% solution of potassium hydroxide in pure water. Alternate electrodes, usually the cathodes, are surrounded by diaphragms that prevent the passage of gas from one electrode compartment to another. The diaphragm, usually made of asbestos, is impermeable to gas but permeable to the cell's electrolyte. The whole assembly is hung from a series of gas collectors. A single tank-type cell usually contains a number of electrodes, and all similar electrodes of the same polarity are connected in parallel electrically, as pictured in Figure A.2-2.26 This arrangement allows an individual A-17 PAGENO="0748" 742 Figure A.2-2: SCHEMATIC DIAGRAM OF UNIPOLOR (TANK-TYPE) ELECTROLYZER tank to operate across a 1.9-2.5 V dc supply.24 In general, the costs of electrical conductors rise as the current load rises, but the cost of ac-dc rectification equipment per unit of output falls as the output voltage rises. This is one important consideration in the design of the tank-type electrolyzers. In general, a single silicon diode can handle voltages in the range of 500-1000 V and all the way up to its peak inverse voltage, which represents the maximum voltage to which the diode can be subjected. Optimum rectifier operation is carried out at voltages just below the diode's peak inverse voltage, and since groups of tank-cell batteries can be connected in series, no electrical problem results. The major advantages of tank-type electrolyzers are twofold: 1. Relatively few parts are required to build a tank-type electrolyzer, and what parts are needed are relatively inexpensive. Because of this feature, tank-type electrolyzers tend to optimize at a lower thermal efficiency than more sophisticated electrolyzer structures. Therefore, tank-type electrolyzers are usually selected when electric power costs are at their lowest. A-18 PAGENO="0749" 743 2. Individual cells may be isolated for repair or replacement simply by short-circuiting the two adjacent cells with bus bar. This feature accommodates a minimum of downtime in producing hydrogen. Some disadvantages of the tank electrolyzers are a) their size, requiring more floor space than other types of electrolyzers*; b) their inability to handle high current densities because they use cheaper com- ponent parts; and. c) their inability to operate at high temperatures because of heat losses from the large surface areas of connected cells. Performance studies have been carried out in India on tank-type electrolyzers where the electrolyte was open to the atmosphere to deter- mine the effect of ambient temperatures on cell operating voltage.22 These results prove that low cell operating temperatures also have a deleterious effect on cell operating characteristics. The lowering of cell temperatures, for example in winter, leads to a reduction in the con- ductivity of an electrolyte, resulting in a nonuniform current distribution. Greater resistance is then encountered in the current flow, resulting in an increase in cell voltage and reduction in gas output. A method of cutting off two cells from one end of the electrolyzer reduces the total resistance of the cell battery whenever the electrolyte temperature falls below a certain recommended operating point. Tank-type electrolyzers that are open to the atmosphere also tend to absorb carbon dioxide at low electrolytic temperatures, causing the forma- tion of solid carbonates that increase the electrolyte resistance and hence the cell voltage.30 In performance studies, the electrolyzers experienced an electrolyte temperature fluctuation that followed the same pattern of fluctuation as the ambient temperature. The more common industrial tank-type designs of electrolyzers, however, have their electrolytes sealed from the atmosphere. * Some proponents of tank-type electrolyzers dispute this point, indi- cating that tank cells can be accommodated in as small a floor space as the filter-press type (described later). In actual commercial in- stallations, however, tank-type cells appear to occupy large areas, though quantitative comparisons are not available. A-19 PAGENO="0750" A.2.4.2 Filter-Press Electrolyzer 744 As an alternative to tank electrolyzers that are `unipolar" or "monopolar," in which a single electrode is either an anode or a cathode, a bipolar electrolyzer exists in which one side of each electrode is used as an anode in one cell and the other side of each electrode functions as the cathode of the next cell.8 Figure A. 2-3 indicates the difference in the layout of electrodes in bipolar cell construction. ~s'ē~~ ~ CELL BATTERY VOLTAGE ~NQ PAIRS OF ELECTROCES - Figure A.2-3 FILTER-PRESS (BIPOLAR) CELL CONSTRUCTION The bipolar arrangement is also known as the filter-press electrolyzer because of its superficial resemblance to a filter press, in which alter- nating layers of electrodes and diaphragms are clamped together. With a construction of this type, the cells are connected in series and individual cell voltages are additive within a battery. Because the cells of a bipolar electrolyzer can be made relatively thin, a large gas output is achieved from a relatively small piece of plant. It is usually desirable to circu- late electrolyte through the cells, thereby separating the gas and the electrolyte, and in many designs this is accomplished in a separating drum mounted on top of the electrolyzer. The electrolyte, free of gas, is recirculated through the cells, the circulation being maintained by gas lift of the generated oxygen and hydrogen. - I A- 20 PAGENO="0751" 745 Although filter-press electrolyzers may be operated at higher current densities and appear to~ occupy relatively less space than tank-type dcc- trolyzers, they require a much closer tolerance in construction and are more difficult to maintain. For example, in a~ filter-press electrolyzer, if an individual asbestos diaphragm is damaged, substantial rebuilding is necessary because the entire battery has to be dismantled and production potential is lost, whereas in a tank electrolyzer, a single inoperable cell may be isolated from a battery by means of a short-circuit bar and any necessary maintenance carried out while the full plant capacity is main- tained, with only a slight increase in specific power consumption. Even though breakdowns in filter-press electrolyzers are rare, when they occur, rejuvenation is difficult and may take a considerable amount of time. ~ Filter-press electrolyzers usually also present greater capital costs than the tank-type electrolyzer. This is compensated for, however, since the filter-press type is able to operate at higher current densities (more hydrogen produced per area of electrode) with virtually the same operating voltages as the tank-type unit. A.2.4.3 Stuart Cell A typical example of the tank electrolyzer cell was developed, manu- factured, and is being further developed by The Electrolyser Corporation, Ltd., in Toronto. A Stuart Cell,4 as it is called, consists of a nickel- plated steel cell tank with positive and negative electrodes arranged alternatively and suspended from the cell cover. Electrodes in a single- cell tank are connected in parallel, and the cell tanks are connected in series to form a cell battery and to promote higher overall voltage and consequent lower rectification costs. This arrangement results in an operating voltage, even in large cells, of approximately 2 V dc.~ As is common with most tank-type electrolyzers, should repair of one cell become necessary, the modular construction of the cell battery permits the isolation of one tank from the line. A temporary bus-bar connection shorts out the damaged cell, and operation is continued until the damaged cell is repaired. A-21 PAGENO="0752" 746 Electrodes used in these cells are made of high-conductivity, high- surface area, sand-blasted steel; the anodes are nickel-plated to prevent corrosion. As in most tank electrolyzers, each anode is surrounded by a woven asbestos cloth diaphragm which prevents the mixing of hydrogen and oxygen. It also guides the oxygen generated toward a storage cham- - ber beneath the cell cover. Hydrogen formed at the cathodes rises between the diaphragms to the hydrogen compartment under the cover. it is not uncommon for these diaphragms to last well over 20 years before replacement. 27 According to A. Stuart,27 the unique and proprietary construction of the Stuart-cell electrodes provides a large surface for electrolysis in a minimum of space. Because of the large active surface of the electrodes, Stuart says, the cells are able to operate at a high total current,but the surface exhibits a low current density. Details of electrode construction are not available publicly. The low cell operating voltage and the physical separation of each cell tank simplifies electrical insulation within each cell and enables efficient sealing against loss of electrolyte and gas product. The elec- trolyte is circulated independently within the cell by means of the lifting effect of the rising gas bubbles. This method requires no moving parts and avoids the hazards and complexity associated with external electrolyte pumping systems. A 10-15 yr or more life expectancy is appropriate before the electrolyte need be replaced. A 28% potassium hydroxide solution is the recommended electrolyte for the Stuart cell. Each of the Stuart cells is supplied automatically with feedwater through individual valves set to maintain correct electrolyte levels and concentrations. A cooling-water header passes along the rear of the cell tank, supplying individual hydrogen and oxygen scrubbers at the cell-gas outlets and a cooling jacket on the back of each cell. The water flow is adjusted to maintain optimum cell temperature; the effluent water is suitable for recycling. As is common with many tank electrolyzers, the Stuart cell operates at a rather low temperature, 158°F (70°C) and low current density, which minimizes waste-heat production. With this arrangement, cell overall efficiency is higher at all levels of hydrogen output than it would be if operated at high current densities. A-2 2 PAGENO="0753" 747 The Stuart cell is rugged and simple to assemble and maintain, and the component parts are fabricated cheaply. Hydrogen is produced at a purity of 99. 9%. The oxygen by-product (99. 7% pure), is produced in the ratio of one part oxygen to two parts hydrogen. Since the Stuart cell is contained in a closed system (not exposed to the atmosphere), no problem with the formation of potassium carbonate from carbon dioxide in the air is experienced. The basic Stuart hydrogen plant is of modular construction in that an unlimited number of cells may be connected in series. By this method, hydrogen production capacity may be increased by simply adding more cells. Typical Stuart hydrogen plants produce hydrogen at the rate of tens of thousand cubic feet per hour. Some uses for this quantity of hydrogen output include the manufacture of semiconductor materials; hydrogen coolant at thermal and nuclear power stations; synthesis of chemical intermediates for long-chain polymer production; hydrogenation of oils and fats in margarine, shortening, and soap production; direct reduction of metal oxides; annealing of stainless and electrical steels; and float-glass manufacture. The cells utilized in the hydrogen plants mentioned above are all of the described construction, but produce from 63. 6 to 350 CF/hr per cell unit with a full loaded weight, ranging from 1665 to 5135 lb. The width of these cells is approximately 12-33 inches. The length of each cell is 44 inches, and the height is 49 inches. The hydrogen production in these cells for each 1000 A per cell is 15.9 CF/hr of hydrogen and 7.95 CF/hr of oxygen. The power consumption (dc) of each cell is 128 kWhr dc per 1000 CF oxygen. Maximum gas production pressure is slightly above atmospheric (10 inches water column).4 The operating costs of a Stuart cell may be inferred from the follow- ing cell requirements. For 1000 CF of hydrogen and 500 CF of oxygen, electric power consumption, including rectification, is 133-145 kWhr ac; demineralized feedwater required is 0. 895 cu ft; and cell cooling water required is 38. 77 cu ft. The cost of hydrogen and oxygen production is dependent on the cost of electricity and water supplies. A-2 3 62-332 0 - 76 - 48 PAGENO="0754" 748 Smaller amounts of hydrogen may be obtained with the Stuart Packaged Hydrogen Generator. The generator is a self-contained, factory-assembled unit capable of producing pure hydrogen in quantities from 20 CF/hr to 1000 CF/hr with an ac power input of 3-140 kW, respectively. The dimensions of these units (in inches) are 25 X 48 X 58 and 48 X 232 X 74, respectively. Cooling water is not required for the 20 CF/hr plant and is 38. 77 CF/hr for the 1000 CF/hr plant. An air-cooled silicon rectifier provides direct current to the cells. Transformer, switchgear, and control equipment are also required. The transformer is needed to step down the alternating current to the necessary low voltage. Multiphase rectification is sometimes necessary to reduce the harmonic loading of the supply. Regulators control the voltage within 60-i00%~ of the maximum needed output and give depend- able variable control. The equipment is normally servo-controlled to give a preset output current and hydrogen production rate. If a hydrogen plant is to be expanded by the addition of more cells in series, a dual- voltage rectifier can be provided whereby *either of two independent voltage ranges can be selected, so that the ratio of maximum to minimum volts will be the same on both voltage ranges. Some applications of these smaller units include hydrogen for labora- tories, inflation of meteorological balloons, hydrogen and oxygen for cutting and welding, and the sintering of metal powders. The Stuart units currently available typically absorb 24. 6 kWhr/lb* of hydrogen produced, operate at 2. 04 V. and have a thermal efficiency of 72%, 28 although current and voltage can be traded off to optimize production cost with electric power cost. A.2.4.4 Teledyne Electra Cell In 1967, Allis-Chalmers Corp. sold its fuel-cell and electrolyzer R&D technology to Teledyne Isotopes Co. Since then, Teledyne has entered the market with a number of electrolyzer cells. * A comparative table of electrolyzer operating characteristics is presented in Table A. 2-1 (page 44). A-24 PAGENO="0755" 749 The current Teledyne Electra Cell systems are of filter-press type and in general consist of modules made of multiple electrolysis cells connected electrically in series by common bipolar plates. The electrodes are separated by a matrix saturated with electrolyte. The matrix pre- vents mixing of the gases and provides a conductive path for the electrical current. As the hydrogen and oxygen are formed, they are kept apart, and the gases from each cell are ducted internally through manifolds to storage containers.14 This electrolyzer uses a potassium hydroxide-water solution (25% by weight) electrolyte with advanced-design porous nickel electrodes and operates at moderate temperatures, lOO°-200°F. The cell contains no precious-metal catalysts. ~ To support the electrolysis module, various subsystems recirculate and cool the electrolyte, add water, condition the product gases, and supply electricity. Teledyne manufactures, or can build to order, three families of hydrogen-producing electrolyzers to suit a user's requirements: 1) gen- erators that produce from 0. 177 to 0. 353 CF/mm, 2) systems that produce from 0. 177 to 7. 06 CF/mm, and 3) plants that produce tons! day.'2 Plants in categories 1 and 2 have been sold commercially, but plants in category 3 have yet to be ordered and built. Small hydrogen generators produce from 0. 177 to 0. 353 CF of hydrogen/mm. Uses for these amounts of hydrogen include carrier gases for gas chromatographs and fuel for flame ionization instruments, primarily in the pollution control and monitoring industry. These small generator units operate from a standard 110 V ac power source and deliver hydrogen at 0-35 psig with a purity of better than 99. 99%. A schematic diagram of the generator system is provided in Figure A. 2-4. The electrolyte is recirculated on the oxygen side of the module to resupply each cell with water and to remove heat. The gen- eration of oxygen gas in the cell provides a gas-lift effect for convective circulation, thereby eliminating the need for a pump. While auxiliaries are available to provide for continuous water replacement, the basic system operates on a batch feedwater refill technique. In most cases, A-25 PAGENO="0756" 750 Figure A. 2-4: SMALLEST TELEDYNE HYDROGEN GENERATOR' heat is removed at the electrolyte reservoir by natural convection to the ambient air, allowing the system to operate at less than 130°F. The electrolyte reservoir also acts as a gas and liquid separator, allow- ingfor the removal of oxygen and for pressure control of the oxygen and electrolyte portion of the system. Hydrogen generated at the liquid- free cathode is manifolded and ducted to a demand pressure regulator for subsequent delivery and use. A pressure switch senses the hydrogen pressure and controls a transformer and bridge rectifier to supply cur- rent when the hydrogen pressure is low. The system then maintains a preset pressure range with the module cycling off and on at a rate de- pendent on hydrogen usage. This small system weighs about 50 lb and is 26 X 14 X 10 inches in size. The only facility interface required is standard a-c electric power. With this unit, high-purity hydrogen can be produced for as low as $3. 10/1000 SCF based on an electricity cost of 10 mills/kWhr.14 A- 26 PAGENO="0757" 751 Larger quantities of hydrogen are available with the Teledyne inter- mediate-size electrolysis systems. Where larger quantities of hydrogen are needed for industrial processing such as the production and sintering of metal powders of iron, nickel, cobalt, and molybdenum or for the bright annealing of stainless steels or electrical utility use, Teledyne intermediate-sized electrolysis units have been sized to provide from 0. 177 to 7. 06 CF of hydrogen/mm. Increased capacity and optimum equipment utilization can be provided by the use of multiple units. Fig- ure A. 2-5 is a schematic diagram of the Teledyne intermediate-size hydrogen generator, which is capable of producing hydrogen with a purity in excess of 99. 99%. Figure A. 2-5: INTERMEDIATE-SIZ ED TELEDYNE HYDROGEN GENERATOR'4 A-27 PAGENO="0758" 752 With this system, which is similar to the smaller generator, elec- trolyte is recirculated on the oxygen side of the module by a centrifugal pump. This arrangement resupplies each cell with water, removes heat, and carries away generated oxygen. A tube-and-shell type heat exchanger is provided to transfer heat to a facility cooling-water loop. Normal system operating temperatures are less than 185°F. Oxygen is separated from the electrolyte in the reservoir, where water is also resupplied. The separated oxygen flows through a condenser to remove excess mois- ture and then flows to a pressure-control device to regulate and control the oxygen and electrolyte loop pressure. Hydrogen generated in the module is manifolded and piped directly to a condenser to remove most of the water vapor and then to a molecular sieve dryer to lower the dew point of the hydrogen to less than -110°F.'4 Three-phase, 460-V ac power is converted and controlled by means of a silicon-controlled rectifier bridge. A pressure transducer senses the hydrogen pressure and signals a logic circuit, which applies current to the module at a level proportional to a preset pressure-range deviation. Thus, the unit continuously generates only the amount of hydrogen de- manded. The system is normally set to deliver hydrogen at 70 psig, but can be adjusted to deliver gas at 100 psig. A number of process monitors are incorporated into the system to provide fully automatic operations. Such parameters as temperature and concentration of electrolyte are controlled variables that aid safe operation and the necessary heat rejection. Start-up, shutdown, and safety par- ameters are continuously controlled. When power is applied to the system for start-up, an inert gas is provided to the system through a solenoid valve and forward-pressure regulator. This prepressurization gas pres- sure is monitored by a factory-preset pressure switch that prevents system start-up until 4 psig is maintained in the hydrogen system. During the initial period after start-up, several subsystems are sequentially activated and monitored to ensure proper general start-up. Following this period, power is applied to the electrolysis module and gas generation begins, allowing the prepressurization equipment to shut down. During any system shutdown, the hydrogen is automatically isolated from the gas- delivery manifold and the system will assume a standby condition and depressurize.'9 A-28 PAGENO="0759" 753 These larger systems weigh from 1000 to 2000 lb per cabinet and have dimensions of 33 X 74 X 64 inches. Industrial 460-V ac three- phase electricity, cooling water, feedwater, and a small inert gas supply are the only other facilities additionally required. This system requires a minimum of maintenance attention. The electrolyte is sampled once per month to determine its specific gravity. After the initial electrolyte change at the end of the first month of operation, the electrolyte is only changed semiannually. Changing of the electrolyte filter, water-flushing of the solenoid valves, and calibration of the pressure switches are all recommended semiannually.29 Depending on the exact size and the application, these units will generate hydrogen continuously at an efficiency in the range of 28 kWhr/ 100.SCF to 17 kWhr/l00 SCF.'4 When quite large quantities of hydrogen are required in terms of tons per day, Teledyne recommends a considerably different system of hydrogen production. A schematic diagram of this system is shown in Figure A.2-6. In this system, electrolyte circulates to both sides of the electrolysis module, which allows more efficient heat removal and simplifies the pressure -control function. The electrolyte is recirculated by a single pump to both the hydrogen and oxygen cavities of the module. Each gas and electrolyte mixture is then returned to a different reservoir and separator, where the two phases are separated. The electrolyte is cooled in a heat exchanger and then mixed with electrolyte from the opposite portion of the system. Makeup water is continuously added at the mixing chamber. The gases are piped through condensers to remove excess moisture, then through a pressure-control device, and finally delivered for use. With this system of "double flooding" the gas-collection chambers, there is a) no pressure differential across the diaphragm or pushing away of the electrodes, which may occur with a large enough pressure differential; b) no concentration gradients across the cell, and therefore no concentration polarization; and c) a more economical produc- tion of hydrogen, since more hydrogen is being produced with the costs and requirements of auxiliary equipment remaining the same. Simple pressure-control devices are incorporated in this cell system to allow an operation of up to approximately 100 psig.17 A-29 PAGENO="0760" 754 Figure A. 2-6: LARGER-MODEL TELEDYNE HYDROGEN GENERATOR'4 These systems can be controlled to provide constant gas-production rates and a specified level of gas purity. Multiple-system packages can be installed to supply virtually an unlimited quantity of hydrogen. Each system occupies approximately 260 cu ft of floor space and will generate hydrogen at an efficiency of 14 kWhr/ 100 SCF. With an electricity cost of 10 rnills/kWhr, hydrogen can be generated at $1. 40/1000 SCF.L4 Although none have been built, Mr. W. C. Kincaide of Teledyne states that the hydrogen plants producing 1-4 tons hydrogen/day would operate at an ~~~ctrical_conditioniflg efficiency of 95% and an electrolysis efficiency of 1.5 v/i. 84 V, or 82%, 1.5 Vbeing the `reaction enthalpy voltage." This specific plant, optimized for a power cost of 6 rnills/kWhr-ton of hydrogen produced, consumes 1.95 MW (three-phase ac) of power, converts itto 5000 A at 370 V dc, and feeds it to a module of 201 cells, with the overall efficiency being 78%.12 A-30 PAGENO="0761" 755 Intermediate-sized units producing approximately 3. 85 CF/mm of hydrogen have an electrical conditioning efficiency of 92% and an elec- trolysis efficiency of 1.5 V/2.25 V, or 67%. Teledynets current electrolysis modules have overall thermal effi- ciencies between approximately 57 and 75%, with cell operating voltages of 2. 4 and 2. 1, respectively. The lower efficiency device represents the smallest electrolysis unit, used for gas chromatography, mnd the higher efficiency machine represents proposed large scale plants (in tons/day). 13 Teledyne is also developing high-pressure electrolysis units for military application, providing oxygen supplies for submarines. Its technique for developing 2000-3000 psi of pressure is to encase the entire cell battery in a stainless-steel pressure vessel which is flooded and pressurized with distilled water. - A. 2. 4. 5 General Electric Solid Polymer Electrolyte Cell General Electric Co. of Lynn, Mass., has been developing a water- electrolysis system based on solid polymer electrolyte (SPE) fuel cell technology. SPE fuel cells were first used in space during the Gemini Program, where they provided primary on-board power for seven of the spacecraft flights. According to GE, certain technological advances in the design of solid polymer electrolytes (SPE) have resulted in a water-electrolysis unit of considerable simplicity in design and operation that can maintain stable and efficient use of relatively expensive electricity supplies. The SPE is a thin, solid, plastic sheet of perfluorinated sulfonic acid polymer, having many of the physical characteristics of Teflon. Chem- ically, the polymer approximates31 - [ CF3 CF31 CF2-CF (-) (~) In [so3 -H . XH2O A-31 PAGENO="0762" 756 Unlike Teflon, however, when a thin sheet of this material is saturated with water, the polymer is an excellent ionic conductor, providing low electrical resistance. Used in an electrolysis cell, it is the only elec- trolyte required; there are no free acids or alkalies in the system. Ionic conductivity is provided by the mobility of the hydrated hydrogen ions (H+ X H20), which move through the sheet of electrolyte by passing from one sulfonic acid group to another. Because the system is solid, the sulfonic acid groups are fixed, keeping the acid concentration constant within the electrolyte. An important feature of the SPE system is~ the simplicity of the electrodes. Because the electrolyte is a solid, the catalytic electrodes are not required either to retain or support the electrolyte, and can therefore be optimized for catalytic activity at minimum cost. Currently, a thin layer of high-catalytic-activity platinum black is attached to the SPE surface to form the hydrogen electrode. A similar layer of pro- prietary precious-~ietal alloy catalyst forms the oxygen electrode. Additional metal current collectors are pressed against the catalytic layers. To date, the system has incorporated the use of niobium or titanium as the current collector and separator sheet materials. A schematic diagram of the SPE electrolysis cell is provided in Figure A. 2_7.21 In this configuration, water is supplied to the oxygen evolution electrode (anode), where it is electrochemically decomposed to provide oxygen, hydrogen ions, and electrons. The hydrogen ions move to the hydrogen-evolving electrode (cathode) by migrating through the SPE. The electrons pass through the external circuit to reach the hydrogen electrode. At the hydrogen electrode, the hydrogen ions and electrons recombine electrochemically to produce hydrogen gas. An excess of water is usually supplied to the system and recirculated to remove any waste heat. The gases produced by the SPE are generated in the stoichiometric ratio of hydrogen and oxygen at any pressure. The electrolyte sheet can withstand pressure differences of up to 1000 psi as well as high gener- ating pressures up to 3000 psi by simply back-pressuring the system. These high generating pressures may be useful in solving transmission and storage problems. A-32 PAGENO="0763" 757 Solid Polymer Electrolyte Cathode Anode Pure Pure Hydrogen Oxygen t /. 4H' + 4e -92H2 2 H20 -9 4W + 4e + 02 (+) 4& Iii Water (reactant and coolant( Figure A. 2-7: SCHEMATIC DIAGRAM OF SPE ELECTROLYSIS CELL2' According to W. A. Titterington, manager of electrolysis development, the use of the SPE results in the following advantages:" a. The cell can operate with high differential pressures (>1000 psia) in addition to high gas-generating pressures. b. The concentration of the electrolyte is fixed, and the electrolyte is not mobile. c. There is no possibility of acid carry-over into the effluent gas. d. There are no corrosive electrolytes to control or leak in the system. e. The electrolyte is eosentially invariant in operation. f. me acid SPE electrolysis unit results in a minimum power require- ment per unit of gas generated. g. High current-density capability can result in optimum design for low capital cost as well as low operating cost. A-33 PAGENO="0764" 758 Although most of the SPE development was done in the past for the space program and aircraft applications, GE now produces two small hydrogen generators for commercial applications. Applications for these generators include the production of hydrogen for gas chromatographs, flame-ionization detectors, and other related areas. Operation of these units requires only 115/230 V ac 50/ 60 Hz power and a supply of distilled water. Both units have a hydrogen delivery pressure of 2-60 psig. One model sells for approximately $850, has two SPE cells with an area of 0. 05 cu ft, and is rated at 0. 005 CF/mm hydrogen flow. The other model sells for $1000, has three cells of 0.05 cu ft area, and is rated at a 0. 008 CF/mm hydrogen flow. Both units require minimal mainten- ance, requiring only an occasional replacement of a desiccant cartridge and water deionizer.6 The two units are both compact, weighing approxi- mately 30 lb each and occupying less than 1 cu ft each. At present, 22 kWhr of power are absorbed per pound of hydrogen produced at an 33 operating voltage of 2. 00 and a thermal efficiency of 74%. A. 2. 4. 6 Life Systems Cell A static feedwater electrolysis system developed by Life Systems, Inc., under NASA sponsorship has been presented for potential applicability for terrestrial hydrogen production. Developed for the space program, the static water electrolysis system concept uses a) an alkaline electrolyte; b) a method whereby the electrolyte is retained in a thin porous matrix, eliminating bulk electrolyte; and c) a static water feed mechanism to prevent electrode and electrolyte contamination and eliminate the need of very pure feedwater.1° In the static water feed system, the water to be electrolyzed is fed to the cell electrolyte as a vapor. Each cell is divided into three main compartments: a water feed compartment, a hydrogen gas compartment, and an oxygen gas compartment. Compartment separation and liquid- vapor phase separation is achieved by the capillary action provided by liquid-filled asbestos sheets. Catalyzed porous nickel plaques support the cell matrix, forming a composite electrolysis site. Plastic screens similarly support the water feed matrix. The cell configuration is given in schematic form in Figures A. 2-8 and A. 2-9, which also show the cell operation. The bottom figure represents a thermally insulated box A-34 PAGENO="0765" 759 IN tIATRIX CASE H20 CATHODE (+) Figure A. 2-8: LIFE SYSTEM'S CELL CONF~GURATION Inlet Bowl Symbolizing Bowl Symbolizing Feed Porous ~1atrix Water Compartment Between Electrodes Figure A. 2-9: LIFE SYSTEM'S CELL OPERATION A-35 PAGENO="0766" 760 in which two bowls of electrolyte are sitting. When power is applied to the electrodes, water in the cell electrolyte is consumed. As a result, the concentration of the cell electrolyte increases, causing its vapor pressure to drop below that of the feed-compartment electrolyte. This differential in vapor pressure is the driving force that causes the water vapor to diffuse across the hydrogen cavity to the cell matrix. Such a system is designed for zero-gravity operation. For terres- trial applications,the diagram in the lower figure would be one bowl of ~1ectrolyte and one bowl of feedwater.'° Gravity applications require that the feedwater be drained out when the current is shut off, otherwise its higher water-vapor pressure would try to equalize the concentrations and flood the matrix. Two major advantages in this cell system became apparent: 1) -the product gases need not be separated from the Leedwater or electrolyte and 2) semipure water may be used, since contaminants rarely lower the vapor pressure of the feedwater. The electrodes and electrolyte rema5n uncontaminated since the water comes to the hydrogen electrode as pure vapor. The sole limit to impurities is the eventual blockage of the feedwater matrix pores. The amount of water transferred is directly proportional to the difference in water vapor pressures of the cell and feed electrolyte. The cell design utilized in the static feed system includes a bipolar plate filter press construction with welded bus bars, providing intercell current connection. The hydrogen electrode is placed directly on the cathodic current collector. Current then flows from the cathode through the matrix to the oxygen electrode. An expanded nickel screen is placed on the back of the anode, providing both a path for the current and a space for oxygen evolution. The major portion of the inefficiency in the electrolysis of water occurs at the anode and must be removed as waste heat. The cell coolant passages were placed directly over the bipolar plate opposite the oxygen cavity. If air cooling is desired, this plate is extended out past the cell frame, forming external fins for convection or forced air cooling.10 A-36 PAGENO="0767" 761 Since Life Systems electrolysis designs were developed for the space program, expensive materials were utilized to provide reliability and efficiency. The system cell frames are injection-molded from high- flame-resistant plastic. All metallic parts are made from nickel alloy, which is then gold-plated. Both the feedwater matrix and the cell matrix are made of Life System's reconstituted asbestos. Other cell materials include stainless-steel end plate and polypropylene screens used to pro- vide structural support for the matrices.10 The electrolyte used is a 35% potassium hydroxide -water solution instead of the more electrically conductive 25-28% solution.10 At higher electrolyte concentrations and at higher temperatures, changes in con- centrations between the water feed and the cell-matrix electrolyte give greater water -vapor partial-pres sure differences. Since this difference is the driving force for the amount of water transferred, this phenomenon is accelerated. Life Systems has developed two static feedwater electrolysis cell designs. One previous unit exemplified the simplicity of the static feed concept. The advanced system is undergoing parametric testing, including current density, voltage,, and temperature relations; effect of pressure on cell voltage; and noble-metal catalyst loading amounts and techniques. Design capabilities of the present systems include - Maximum pressure 600 psi Maximum temperature 220°F (with asbestos, long-term degradation starting at 200°F) Maximum current density 1000 A/SF- single-cell, short periods 600A/SF- multicčll Power requirement 117 kWhr/1000 SCF of hydrogen at 600A/SF Single-cellarea 0.10 cu ft A-37 PAGENO="0768" 762 A. 2. 4. 7 ~ High-Pressure Ce11Z7 Of the many electrolyzers produced in other countries, the Zdansky- Lants electrolyzers, manufactured by the Lurgi Company, are particularly noteworthy, since these electrolyzers, working under a pressure of 30 atmospheres, are very economical, compact, and reliable. The Lurgi electrolyzer is basically of the filter-press type. In each cell of the electrolyzer, between two round, nickel-plated discs pressed in nickel-plated gaskets, are pressed reticular venting electrodes, diaphragms made of pressed asbestos, and sealing and insu- lating gaskets. The gas manifolds are located within the cells and are formed by rings of Teflon with holes for connecting the inner space of the cells to the gas channels. The cells are very narrow, making it possible to connect several hundred cells (up to 500 cells in the largest electrolyzer) into one relatively small apparatus. Forced electrolyte circulation is used in the Lurgi electrolyzer; A pump forces cool electrolyte through an asbestos filter into the lower manifold of the cell bundle. The electrolyte is cooled in the gas sep- arators by means of coils built into storage drums through which the coolant and condensate circulate. The condensate is pumped through a closed loop and is cooled in an adiabatic heat exchanger. The total volume of condensate in the cooling system of an electrolyzer consisting of 250 cells with a capacity of 10, 543 CF/hr of hydrogen is 28. 25 CF. Hydrogen and oxygen are manifolded into separate collection chambers. A floating valve is installed inthe oxygen gas separator to regulate the escape of oxygen and to maintain a constant electrolyte level in the gas separator. Desalinated feedwater is provided to the cells by means of the so-called va~riable-ratio pump, the capacity of which is adjusted manually, depending on the load of the electrolyzer. If the electrolyte in any of the gas separator drums drops, the corresponding safety floating valve is opened and the gas whose pressure was too high is vented into the atmosphere. As the level in one of the gas separators continues to drop, a magnetic relay shuts the electrolyzer down. A-38 PAGENO="0769" 763 During start-up of the Lurgi electrolyzer, the electrolyte, prepared in a tank in an atmosphere of nitrogen (to prevent absorption of carbon dioxide gas from the atmosphere) is heated in the makeup tank to 171°F and pumped into the electrolyzer. The gas separators are blown with nitrogen, during which the working and safety valves and relay are checked. The circulation pump is turned on and the flow rate of the electrolyzer is set by a rotameter (282. 5 CF/hr for an electrolyzer with a capacity of 10,593 CF/hr). The electrical load and pressure are increased simultaneously. When the current reaches a nominal level of 3000 A and the pressure increases to 30 atm, the gases are delivered. At this point, the feedwater pump and current stabilizer are turned on and the electrolyzer is brought up to normal operation. During normal operation, the electrolyte temper- ature in the apparatus is maintained at about 203°F and the pressure is 30-31 atm (regardless of the gas pressure used). The low voltage on the electrolyzer cell of 1. 8 provides a high efficiency of operation. Prolonged reliable operation of the apparatus with this low energy consumption is possible only if extremely pure water is fed to the cells. After shutdown of the electrolyzer, the circulation pump continues to operate for 1 hour after the current is turned off. If the shutdown is for a period of more than 30 minutes, the electrolyzer is purged with nitrogen after the gas pressure is reduced. If the temperature of the electrolyzer drops to 104°F after shutdown, the electrolyte is heated or drained into the preparation tank. It is important that electrolyte draining does not take place earlier than 2 hours after depressurization, since considerable quantities of dissolved hydrogen and oxygen would otherwise be liberated from the solution into the alkali tank, producing flammable mixtures. A-39 62-332 0 - 76 - 49 PAGENO="0770" 764 A. 2. 4. 8 Comincol One of the largest hydrogen plants in the world is located in Trail, British Columbia, Canada. Although it has been shut down now for over a year because of rising power costs, this plant presents the first North American attempt at large-scale hydrogen production. Individual cells are of Cominco patent design. The characteristic feature of this tank-type cell is a concrete top which supports the elec- trodes, the asbestos diaphragms, asbestos collecting skirt, feedwater pipes, bus bar, and gas-main connections. In this concrete cover also are the two gas chambers for hydrogen and oxygen and the narrow, inverted_trough-like collecting bins. The cell tank itself is made of iron, while the electrodes are made of mild steel plates and the anode 28 is nickel-plated. The anode current density is 67 A/sq ft. This hydrogen plant contains 3229 individual cells, with a total theo- retical hydrogen_producing capacity of 41 tons hydrogen/day. The cells operate at about 2. 1 V, the current efficiency is close to 100% at atmos- pheric operating pressures, ac-dc rectification is provided, and the overall a-c power consumption is about 60, 000 kVThr/ton of hydrogen.'9 Some cells have life spans of over 20 years, during which the usual operating tempera- ture was 140°F. According to J. N. Robinson of Cominco, "Our cell is very wasteful of floor space, and at today's building costs, it would probably be much cheaper to install a filter-press type of cell. On the other band, we can cut out individual cells from overhaul without appreciable interruption of production, whereas if anything goes wrong with a filter-press unit it represents a substantial production loss and requires a long time to repair. Costs for operating labor and supplies should be quite low on any well-designed electrolytic plant, but costs for maintenance are likely to be high, the diaphragms being the weak point on all cells. ,,18 Mr. J. Ross of Cominco mentioned that recent cell corrosion, leakage of hydrogen between anode and cathode spaces, and deterioration of con- crete cell covers were problems associated with operation of the Cominco cell. ~ A-40 PAGENO="0771" 765 A. 2. 4. 9 DeNora E1ectroly~~ The De Nora Co. of Milan, Italy, manufactures large industrial electrochemical proce s sing plants and includes water-electrolysis in its range of products. Of the three large electrolysis installations built since 1945, De Nora built the 1, 059, 300 CF/hr plant at Nangal, India. (The other two are a 1, 059, 300 CF/hr plant in Norsk-Hydro, Norway, with its own Zdansky-type electrolyzers, and the 706,200 CF/hr plant at Kima, Egypt, built by Demag, of Germany.) All these units are of bipolar, filter-press construction. The standard De Nora electrolyzer3 consists of rectangular cells 16.4 feet wide by 5.25 feet high. These are stacked in series on either side of a cooling chamber and are surmounted by- an electrolyte/gas separation unit. A photograph of a typical cell stack is shown in Figure A.2-1Q. A unique feature of the De Mora design is the use of a double diaphragm. Two distinct layers of woven asbestos are used. These are in physical contact with each other, but the space between them is vented to atmosphere. In normal operation, the diaphragms are pressed against one another, but any penetration of gas bubbles results in the formation of a larger bubble between the diaphragms, which is vented to outside, and thus cannot intermix with the opposing gas. Electrodes are single-layer sheet metal, perforated to allow gas exit, having a proprietary electrolytic surface treatment to develop a high surface area. No precious-metal catalysts are used. The electrodes are of low- carbon steel, and the anode is nickel-plated. The Nangal plant consists of 60 units, each with 108 cells. Each cell stack is 16. 4 x 5. 25 x 49. 2 feet in size and consumes 12, 000 A at 2. 2-2.3 V per cell, 250 V per unit, or 3 MW per unit. Thus, the entire plant consumes 180 MW dc. A-41 PAGENO="0772" i Figure A.2-1O: DE NORA WATER ELECTROLYZER3 PAGENO="0773" 767 DeNora's standard cell sizes are of 2500 A, 4500 A, and 10,000 A capacity, and operate at about 180-200 A/sq ft. The Nangal plant, built in 1960, had a guaranteed performance of 2. 1 V per cell at 10, 000 A. Any new plant delivered today would have a guaranteed performance of 1. 85 V at 12, 000 A,34 made possible by better activation treatment of the electrode. Future performance of 1. 80 V at 18, 000 A (300 A/sq ft) is believed to be possible by the incorporation of a homogeneous catalyst dissolved in the electrolyte, an approach which seems to be unique to Dc Nora. A. 2. 5 Comparitive Evaluation of Various Electrolyzers Figure A.2-ll is a comparison of cell operating performances of various advanced electrolyzers. These data are meant to give only a technological comparison of cell types and not of economics. A cell comparison based on voltage-current relationships is meaningless unless cell cost is included. Interestingly, data are shown near the 1. 47-V point and below at current densities as high as 50 A/sq ft. Under these conditions, the cell operates "thermoneutrally, " and the apparent thermal efficiency is 100%. This gives some confidence that electrolyzer efficiencies approach- ing 100% can be achieved in practical units. At present, however, oper- ation of the GE cell below 1000 A/sq ft will cause proportionate increases in the effective capital cost, upward from $ 213/kw. Commercial elec- trolyzers now cost about $ lOO/kW at 70% efficiency. Figure A.2-12 represents the cost of hydrogen produced assuming various electrical power costs. Inthis figure, Stuart and Teledyne costs represent estimates based on actual commercially sold units, whereas GE cell infor- mation does not. The data for this figure were obtained individually from each company concerned by specific request of IGT and have not been stan- dardized to a uniform financing method. In other words, it is not certain that the amortization rates, cost of money, return on investment, etc., assumed by each company were the same. A- 43 PAGENO="0774" U, 0 > w 0 > -J -J 0 0 z 0~ 0 768 Figure A. 2-12: COSTS OF HYDROGEN AS PRODUCED BY VARIOUS PROCESSES 50 200 250 300 350 cL~RENT DENSITY, A/sq ft Figure A. 2-11: COMPARATIVE PERFORMANCES OF ELECTROLYZER SYSTEMS 0 2 3 4 5 6 7 8 9 0 II 2 3 4 15 16 ELECTRTCITY COST rnills/kWhr A-44 PAGENO="0775" 769 It is not possible to offer definitive comment on the overall merits of the various types of electrolyzer design. Clearly, each approach has its own advocates, and its own merits and problems. It appears likely that several different types of electrolyzers are likely to be developed and used simultaneously. At the present time, among the four large- scale plants, three are of the filter-press type and one is the tank type, none using expensive electrodes. On the other hand, more research effort seems to be, at present, applied to the expensive, sophisticated electrodes than to conventional types. In the view of De Nora, `tank type cells are obsolete," and "small area cells will never get anywhere commercially." It holds the view that commercial cells can never sustain the cost of porous electrodes, precious-metal catalysts, or sophisticated diaphragms. On the other hand, Electrolyser Corp. regards the tank-type cell as a robust, reliable, and profit-making commercial unit, but shares the view that only the cheapest and simplest electrodes and diaphragms can be tolerated. In direct contrast is the approach of Teledyne, which considers the advan- tages of controlled pore-size porous-metal electrodes to be worth the extra cost, GE believes that not only the use of platinum catalysts but also of a considerably more expensive electrolyte, the SPE system, is justified by the higher performance obtained. It may be significant that neither Teledyne nor GE has yet installed any really large plants, but that they share a unique capability of operating at or near 100% electrical efficiency. Another radical difference in design philosophy is apparent from a casual inspection of the various systems. The commercial units of Electrolyser and De Nora are dominated in size and in technical emphasis by the electrochemical cells themselves, whereas the units of Teledyne, GE, and Life Systems are dominated in size and in technical complexity by their auxiliary pumping, pressure control, electrolyte management, and electronic automation equipment (characteristic of the aerospace industry from which they have developed). A-4 5 PAGENO="0776" 770 It appears that the various design philos9phies could result in hydrogen- gene ration techniques quite different in concept from each other, yet all of industrial significance in appropriate applications. A.2.6 Ultimate Potential Present and future overall efficiencies of various electrolyzer cells are given in Table A. 2-1. A. 2.7 Besear ch and Develo ruent Req~ir ements - Engineerin~Prob~erns~ A.2.7.1 Stuart Cell According to A.K. Stuart of Electrolyser Corp., both cell improve- ments and total hydrogen plant development are necessary to improve Stuart cell hydrogen production. An increase in cell operating temperatures (2.-year goal) from the current 15 8°F to 194°F is expected to increase the overall thermal efficiency by lowering the operating voltage. Stuart's 2-3 year goals for electrolyser development include 22. 9 kWhr/lb of hydrogen produced, an operating voltage of 1. 9, and a thermal efficiency of 77%27 Stuart feels some exploration of advanced diaphragm materials will be necessary to handle the higher temperatures of operation. Present asbestos diaphragms can possibly handle these temperatures, but the upper limits consistent with satisfactory life are not yet known. Life testing is being carried out now. Additional electrode development has the potential to lower cell overvoltage.Z? Some scale-up of present cells is expected, as mentioned in Stuart electrolyzer technology; however, overall plant development is needed to provide the best economics. The economic conversion of shaft power to high d-c current is considered by Stuart to provide the best opportunity for improved future operation of his cells. Acyclic generators rated at 250, 000 A dc would be connected directly to high-current cells. Acyclic generators would not require the switchgear or transformers needed with the more conventional ac-dc rectification equipment. The capital costs for conventional ac-dc conversion are approximately $40/kW whereas capital costs for an acyclic generator are expected to be about $1O/kW.Z7 A-4 6 PAGENO="0777" Future (Ultimate) Potential kWhr/lbV ~ 15 1.24 118 15 1.24 118 14.96 1.24 119.8 Table A. 2-1: PRESENT AND FUTURE COMPARISON OF OVERALL EFFICIENCIES OF VARIOUS ELECTROLyZER CELLS Presently Available 2-5 Year Projection Manufacturer Potential Potential kWhr/ lb V kWhr/lb V % Teledyne 32 2. 1 75 22- 1.8- 82- 19 1.6 92 General Electric 22 2.0 74 18- 1.5- 98- 22 1.8 82 -4 Stuart 24.5 2.04 72 22.8 1.9 77 Life Systems 20.5 1.7 87 18.1 1.5 98 De Nora -- 1.85 80 -.- 1.8 82 ~ % efficiency defined by higher heating value of hydrogen produced x 100. electrical energy consumed PAGENO="0778" 772 According to Stuart, no heat-transfer problem is expected when his cells operate from a 250,000-A dc source. Heat transfer associated with Stuart-cell scale-up has not posed any problem in a series of scale-ups. Stuart cells operate at a current density of 125 A/sq ft and have gone up to 500 A/sq ft without evident heat difficulty.27 A.2.7.2 Teledyne Electra Cell Future expectations for 2-5 year developments include electrolyzer cells consuming 22-19 kWhr/lb at an operating voltage between 1.8 and 1. 6 and an overall thermal efficiency between 82-92%. Ultimate goals project the development of a cell consuming 15 kWhr/lb of hydrogen having an operating voltage of 1. 24 at 118% thermal efficiency, which is almost congruous with the thermodynamic limit. 13 Teledyne mentions certain goals to be attained for the future. Increased operating efficiencies can be achieved by the use of noble-metal catalysts on the electrodes in the modules; but in some cases the addi- tional increase in capital costs can more than offset any advantage gained. Teledyne is presently engaged in continuing the development of low-cost catalysts that would lower overvoltages. Mr. Kincaide of Teledyne mentions that improvements in cell operating temperature capability are expected within the next 2 years and should produce operating efficiency improvements of 15%. Along with temper- ature, improvements in cell materials must be developed to withstand the increased temperatures. It is expected that present asbestos diaphragms or gas separators will not be able to withstand increased temperatures of operation, and research is being undertaken to alleviate this problem. Teledyne revealed that it has had problems in obtaining good com- mercially manufactured parts for its electrolyzers. In -many instances it has developed its own system parts to meet close tolerances and specifications. A- 48 PAGENO="0779" 773 All Teledyne systems presently operate at pressures higher than ambient. An insignificant power penalty (0. 431 kWhr/lb of hydrogen at 100 psia) is realized when compared with conventional compressors. Teledyne realizes the importance of generating hydrogen at high pressure when storing and transmitting large amounts of the gas. 14 Present sys- tems are limited in their operating pressures by structural features. One specific question being reviewed by Teledyne is that `Does one design a cell stack to withstand pressure or should a pressurized tank be placed around an existing stack? ` Studies are being performed to determine the demand and cost effectiveness of high-pressure systems in commer- cial applications. 13 Teledyne is building electrolytic gas generators for the U.S. Navy that operate at pressures up to 3000 psig. Power penalties for generating gas directly at this pressure are less than 1. 197 kWhr/lb. A. 2. 7. 3 GE Solid Polymer Electrolyte The future of the GE cell seems to lie in operations at very high efficiencies, or else at very high current densities, thus reducing power costs to a minimum, making the relatively high capital costs justifiable in giving a high hydrogen-production rate. Since these cells will also operate at higher current densities, a greater hydrogen-production rate is realized per unit area of floor space required. It is GE's objective to further improve the thermal efficiency of the SPE cell system and to develop lower cost materials and manufacturing processes in order to achieve a cost for large-scale production of electrolytic hydrogen of $2- $3 /rnillion Btu (1974 cost basis), as suming electrical power costs in the range of 5-10 mils/kWhr. Mr. Titterington lists four specific elements to be included in a long-range development program: 1) electrolysis module development, 2) system definition, 3) 5-MW prototype demonstration, and 4) incorpor- ation of advanced technology. The SPE electrolysis module technology is limited mainly by the cell operating temperature and lack of suitable cell-component materials. The temperature effect on electrolysis cells is shown in Figure A. 2_l3.31 A-49 PAGENO="0780" 774 The importance of cell operating temperature is reflected by the fact that an increase in temperature from 800 to 220°F decreases power con- sumption by 10% for the same amount of hydrogen produced. If cell operating temperatures as high as 300°F can be reached, the theoretical decomposition voltage of water decreases from 1. 18 V at 180°F to 1. 12 V. It is anticipated that at 300°F, the cell sealing techniques or gasket material may become a problem since they cannot withstand high temp- eratures and wet environments. Titterington mentioned that newly developed fluorosilicone rubbers would be evaluate for this application. If these are not compatible, sealing concepts that utilize the SPE directly as a gasket-type seal'would be developed. Experience has also been obtained at gas-generation pressures up to 3000 psia, with the resulting effect on performance shown in Figure A. 2-14. Figure A.2-l3: PRESENT SPE WATER ELECTROLYSIS PERFORMANCE CAPABILITY AT AMBIENT CELL PRESSURE Figure A. 2-14: EFFECT OF HYDROGEN PRESSURE ON GE CELL VOLTAGE A- 50 PAGENO="0781" 775 Thus, considering a cell that has a voltage of 1. 85 V dc at 1000 A/SF, 180°F, and 15 psia gas pressure, the performance would decrease to 1. 90 V dc at a hydrogen-generating pressure of 400 psia. This must be taken into consideration in the system power trade-off studies requiring high-pressure operation. To date, the SPE electrolysis systems have used niobium or titanium as the collector of separator-sheet materials, in spite of statements that the SPE is noncorrosive. Niobium is quite expensive, at $40-$50/lb; titanium, however, offers a desirable price of $ 8/lb. Cell operation at 300°F may result in hydrogen-embrittlement problems with titanium. ~o Therefore, Titterington states that alternative materials including moly- bdenum, zirconium, and various alloys of these materials should be tested for compatibility in high-temperature SPE electrolysis. The present SPE is 12 mils thick in the currently manufactured cells. Considerable voltage reductions could be attained by cutting the present thickness in half. Titterington suggests that minor modifications in both the cell-fabrication technique and hardware design would be required. It is expected that even thinner SPE's could further lower the electrical resistances, and more experimentation is to be conducted. It must also be remembered that as SPE thickness is decreased, its cost is also proportionately decreased. Thus, a 6-mil SPE has a projected cost of $5/sq ft versus the $10/sq ft for a 12-mil SPE. Alternative lower cost SPE's are currently under development and offer costs as low as $2/sq ft. Two other areas of research that may provide future economic ad- vantages for the SPE cell are lessening of catalyst loadings on the elec- trodes and the advancement of catalytic electrodes. Progress in these areas could result in lower capital costs for the entire cell and lower overvoltages at both the anode and the cathode. The present cathode catalyst is platinum black with loadings of 4 mg/sq cm. A proprietary metal-alloy catalyst is applied to the anode, also at a loading of 4 mg/ sq cm. Expectations of catalyst loadings on both electrodes as low as 1 mg/sq cm are conceivable. Further studies should be carried out to determine the mechanisms of the catalytic activity and the dependence of this activity on catalyst geometry and reactions between a catalyst and its environment. A-Si PAGENO="0782" 776 Mr. Titterington suggests that, before larger electrolytic plants are designed, life tests on cell components and a total analysis of a water electrolysis plant must be carried out to optimize the overall plant system relative to hydrogen production costs, plant safety, reliability, and life. GE proposes a 5-MW prototype SPE water-electrolysis system to be fabricated and evaluated over a 2-year period. Preliminary calculations have shown that approximately 2500 sq ft of cell will be required for this plant and that it will generate 250 lb/hr of hydrogen.33 GE estimates that a 5-MW unit could be built today with no additional research; however, it would have a capital cost of $ 560/kW. Capital costs, provided scale-up and cell improvement programs are funded, could be reduced to $56/kW by 1980 and to $44/kW by l985.~~ Power requirements, operating voltages, and thermal efficiencies for GE's electrolysis cells are 18-22 kWhr/lb, 1.5-1.8 V, and 98-82% for 2-5 year goals, and 15 kWhr/lb, 1. 24 V, and 118% for ultimate development.33 A.2.7.4 Life Systems' Cell Life Systems' cells projected capabilities for 1975 are - Maximum Pressure 2000 psi Maximum Temperature 300°F - short periods Maximum Current Density 1500 A/SF Power Requirement 129 kWhr/1000 SCF of hydrogen at 1500 A/SF Single-Cell Area 0.10 sq ft Studies are under way at Life Systems to evaluate an alternative diaphragm material suited for high-temperature (>200°F) electrolysis. Potassium titanate has shown some excellent high-temperature and long- life stability capabilities. Additional studies are also being conducted to investigate the availability of alternative structural materials suited for high-temperature applications to enable cell operation with lower elec- trolysis power requirements. Advanced designs, using zirconia and ytt ria-thoria ceramics for solid electrolytes are being evaluated. These electrolytes conduct only at temperatures above about 1490°F. Advanced catalyst development is also being performed to increase electrode per- formance and lower costs. This work is being conducted in parallel with the high-temperature research to develop high-pressure, large-scale hydrogen generation.'° A-52 PAGENO="0783" 777 In designing its larger electrolysis schemes, Life Systems speculates that many smaller cells connected in series may be more economically and technically feasible than a smaller group of larger cells. R. Wynveen of Life Systems suggests that effective current distribution over large electrode areas (4 x 4 feet) would present design problems, including heat removal. ~ This opinion is in direct conflict with that of Mr. Trisoglio of De Nora, who believes that large single cells of 5 or 6 sq m are essential. A. 2. 7. 5 Acyclic Generators In the detailed design of a large hydrogen-generation plant, not only is the electrolysis cell itself an important system-design feature, but d-cgeneration costs must also be evaluated and optimized. The acyclic generator, also known as unipolar or homopolar, has emerged as a newly designed modern machine with great promise for industrial use. Its basic principle of operation is not new, but the techniques of machine construction that now provide a highly efficient and reliable generator are significant. This machine is able to generate noncyclic voltage, resulting in pure direct current available at the terminals. The development of liquid-metal current collectors has been the feature in converting the acyclic generator from an impractical and in- efficient machine to the very practical and very efficient machine it is now. Overall energy efficiencies have been raised from 75% to 98%, with a current rating of 250, 000 A. A high-speed acyclic generator with liquid-metal collectors has been developed by GE. Four large units have been in service at the Arnold Engineering Development Center in Tennessee for over 12 years. A much smaller unit is installed at Argonne National Laboratory, Chicago, capable of about 20, 000 A at 5 V continuous. The acyclic generator is limited on available rating variations. The optimum speed, voltage, and ampere ratings are held in fixed relationship. This limitation has been the major barrier to date in industrial applica- tions of the acyclic generator. The economic evaluation frequently becomes unfavorable when the application requirements do not match the acyclic generator capability. A-53 PAGENO="0784" 778 Several recent cost estimates have been obtained from GE for gen- erators in terms of 50 and 100-MW capacities5: Generator Up to 50 MW 100 MW $/kW ac 10 10 ac-dc Converter 60 30-50 30 Z5 d-c Acyclic Generator 9 7 From these figures, it can be seen that the cost of a-c generators plus converters range over the unit size from $40 to $35 kW, whereas the d-c acyclic generator costs S9-$7/kW, for a saving of $3l-$28/kW. This is a significant amount when compared with the estimate of $40-$ 501 kW for the entire electrolyzer at the 1000-MW size. In view of these advantages, the acyclic generator should be an integral part of electrolytic hydrogen production. However, Mr. Trisoglio of De Nora claims to have studied the application of acyclic generators for water electrolysis and for other electrochemical applications and has concluded that the additional costs of bus bars and other equipment needed to use these low-voltage generators is in fact greater than the cost of rectifiers for a-c use. This result was obtained in a system study for a 550, 000-A unit, with cell stacks operating at generator voltages of 2 V or so for acyclics and 600 V or so for ac-dc rectifiers. De Nora's opinion itself is in direct contrast with that of the Electrolyser Corp., although at this time, no major electrochemical plant has ever been constructed to operate from acyclic generators. A-54 PAGENO="0785" 779 A.2.8. References Cited 1. Chapman, E. A., Production of Hydrogen by Electrolysis,' Chem. Process Eng. 46, 387-93 (1965) August 8. 2. Daniels, F. and Alberty, R., Physical Chemistry, 3rd Ed., 246-48. New York: John Wiley, 1967. 3. "De Nora Water Electrolyser, ` Oronzio De Nora Implanti Elettrochimici S. p. A., Milano, Italy, n. d. 4, The Electrolyser Corporation Ltd., Electrolytic Hydrogen Plants and Generators. Toronto, n. d. 5, Escher, W., Escher Technology Associates, private communication, December 23, 1971. 6. General Electric Co., Aircraft Equipment Division, `Hydrogen Generator for Gas Chromatographs, Publ~.c-3-74-l. Lynn, Mass., December 1974. 7. Gregory, D. P. etal., A Hydrogen-Energy System, A. G. A. Cat. No. L21l73. Arlington, Va.: American Gas Association, August 1972. 8. Goldshtein, A. G. and Serebryanskii, F. Z., "Operation of Electrolytic Installations for the Production of Hydrogen and Oxygen.' Washington, D.C., Joint Publications Research Service, 1970 (original in Russian). 9. Hampel, C. A., Ed., The Encyclopedia of Electrochemistry. New York: Reinhold, 1964. 10. Jensen, F. C. and Schubert, F. H., "Hydrogen Generation Through Static Feed Water Electrolysis. " Paper presented at the Hydrogen Economy Miami Energy (THEME) Conference, Miami Beach, March 18-20, 1974. 11. Kincaide, W. C. and Williams, C. F., Storage of Electrical Energy_ Through Electrolysis, 15. Timonium, Md.: Teledyne Isotopes Co., 1973. 12. Kincaide, W. C., Teledyne Isotopes Co., private communication, May 10, 1973. 13. Kincaide, W. C., Teledyne Isotopes Co., private communications, June 22, 1974. 14. Laskin, J. B., "Electrolytic Hydrogen Generators." Paper presented at The Hydrogen Economy Miami Energy (THEME) Conference, Miami Beach, March 18-20, 1974. A-55 62-332 0 - 76 - 50 PAGENO="0786" 780 15. MacMullin, R. B., `The Problem of Scale-Up in Electrolytic Processes," Electrochern. Tech. 7, 7 (1963) Jan. -Feb. 16. "More Life for Diaphragm Cells, `~ Chem. Week, 32 (1973) October 31. 17. Newitt, D. M. and Sen, H. K., "The Production of Hydrogen and Oxygen by Electrolysis at High Pressures," Inst. Chem. Eng. Trans. 10, 22-34 (1932). 18. Robinson, J. N., Corriinco Ltd., private communication, January 26, 1971. 19. Ross, M., Cominco Ltd., private communication, May 29, 1974. 20. Russell, L. H. Nuttall, L. I. and Fickett, A. P., "Hydrogen Generation by Solid Polymer Electrolyte Water Electrolysis." Paper presented to the American Chemical Society, Division of Fuel Chemistry, Chicago, August 1973. 21. Schubert, F. H., Status of the Life Syster Static Feed Water Electrolysis System. New York, The American Society of Mechanical Engineers, July 1971. z~. Seshadri, N., "Performance Studies on an Electrolyser for the Production of Hydrogen," Indian J. Tech. 8, 65-70 (1970) February. 23. Silman, H., "Electrolytic Hydrogen - Its Manufacture and Applica- tions," Chem. Ag~ 9~, 126-27 (1965) January 16. 24. Smith, D. H., "Industrial Water Electrolysis," in Kuhn, A. T., Ed., Industrial Electrochernical Processes, 133. Amsterdam: Elsevier, 1971. 25. "Solid Electrolytes Offer Route to Hydrogen," Chem. Eng. News, 15 (1973) August 27. 26. Stuart, A. K., "Modern Electrolyser Technology." Paper presented at the American Chemical Society Symposium on Non-Fossil Fuels, Boston, April 13, 1972. 27. Stuart, A. K., The Electrolyser Corporation Ltd., private com- munication, June 11, 1974. 28. Sutherland, B. P., "Electrolytic Hydrogen Cells of Frail Design." Paper presented at the Electrochemical Society Meeting, Milwaukee, April 17, 1974. 29. Teledyne Isotopes Co., ~y4~9genfOxygen Gas Generator Systems, Timonium, Md., n.d. 30. Thorpe, J. F. and Funk, J. E., "Fluid Flow Aspects of Water Electrolyzers." Paper presented to the Division of Fuel Chemistry, American Chemical Society, Boston, April 10-14, 1972. A- 56 PAGENO="0787" 781 31. Titterington, W. A. and A. P. Ficket, "Electrolytic Hydrogen Fuel Production With Solid Polymer." Paper presented at the 8th Intersociety Energy Conversion Conference, Philadelphia, August 13, 1973. 32. Titterington, W. A., `Status of GE Company SPE Water Electrolysis for Hydrogen/Oxygen Production." Paper presented at the World Energy Systems Conference, Hurst, Texas, June 9, 1974. 33. Titterington, W. A., private communication, June 10, 1974. 34. Trisoglio, G., De Nora S.p.A., private communication, June 28, 1974. 35. Wynveen, R., Life Systems, Inc., private communication, June 23, 1974. CML/~N A- 57 PAGENO="0788" 782 A.3 - PRODUCTION OF HYDROGEN BY COAL GASIFICATION A.3.l - Introduction There are a number of processes by which hydrogen nay be gen- erated. The particular hydrogen generation process which is used in any installation depends on the quantity of hydrogen needed, the price and the availability of feed stocks and the price of power currently in the United States. For small scale generation of hydrogen (up to 200 cubic feet per day), the electrolytic meth- od is most convenient, even if the price of electricity is high. In the intermediate range (200-20,000 CF/D), the cracking of ammonia isa very practical method, if thepresence of nitrogen is not ob- jectionable. In larger capacity applications, hydrogen is now most economically made by steam reforming of natural gas or naphtha. The purity of the hydrogen generated from natural gas or naph- tha is generally in the 95-98 percent range if CO2 removal is ac- complished by MEA scrubbing. By the addition of pressure swing adsorption units, a methanation reactor, or with cryogenic up- grading, hydrogen purity of 99.999 percent can be achieved (Ref. 1,2). There are a number of uses which require large quantities of hydrogen. The principal large users are the ammonia synthesis plants. This is followed by the petroleum refining oparations such as hydrogenation, hydro-desulfurization, hydrocracking, etc. The first synthetic ammonia plant in 1913 used hydrogen gen- erated from coal. Coal remained the principal starting material for hydrogen until the late l940's. Despite the recently tripled price of naphtha, the reverse trend to coal has not yet occurred (see Table A.3-l) (Ref. 3,4,5). A.3.l.l - Historical Background The conversion of coal to gas originated in the late 18th century. Coal was gasified by heating it in the absence of air. The gas produced was called coal gas. The first coal gas company in the United States was chartered in 1816. The primary goal A-58 PAGENO="0789" TABLE A. I~l -LIST OF HYDROGEN PLANTS UNDER CONSTRUCTION * COMPANY Standard Oil Co. PLANT SITE Richmond, Calif. PROJECT Hydrogen CAPACITY - ESTIMATED COST ~ - STATUS LICENSOR H 75 KTI . . ENGINEERING BRAUN CONTRACTORS BRAUN Calif. Murphy Meraux, Oil Co. Kuch Lousiana Hydrogen 40.0 MM CF/D - E 76 PARSONS RN PARSONS RN Rfg.Co. Pine Bend, Minn. Hydrogen - 15.0 U 74 ~ - PARSONS RM . PARSONS RH Standard Perth Oil Co. Calif. Amboy, N.J. Hydrogen - P 75 FW FW S Shell Chemical Marietta, Hydrogen .5 HOWE - HOWE- BLAW Co. Ohio MM CF/D - U BAKER BAKER KNOX Irving RFG. Ltd. Saint John New Bruns- wick,Can. Hydrogen - - U 73 - FW FW PetiEoquim Gen. Mosconi Ensenada (Argen- (tina Hydrogen 38.5 T/D 60.0 S U 74 GERMAN LINDE . GERMAN LINDE McKEE Bahamas Freeport, Hydrogen 25.0 S Dir Rfg. Bahamas MM CF/D - U 74 - BADGER BADGER Co. Petr. Salvador Hydrogen 1.0 Brasil . . Brazil MM CF/D 17.5 U 74 - FW - SA Petr. Brasilieio * San Jose Campos, Brazil Hydrogen 12.0 MM CF/D 180 E 77 - SNAM PROGGETT SNAM PROGGETT EB~resa Columbiana . Barranca- Beameja, Colombia Hydrogen 14.0 MM CF/D - 5 - P 76 . A- 59 PAGENO="0790" PLANT SITE ESTIMATED COST MM$ PROJECT CAPACITY COMPANY St.Croix Petro- St.Croix Hydrogen Virgin 5.7 MM CF/D - E 74 HOWE-BAKER FLUOR chemical Islands Corp. Ind. Siciliana Siracusa, `Italy Hydrogen 18.3 MM CF/D - U 74 ERECO SHAM PROGETT SNAM PROGETT Asfalti .B Empresa Natl. Tarra- gona Hydrogen 10.0 MM CF/D - U 75 UOP TECNICA REU STAFF Petr. (Spain) Tarrag Tech Mash- Import Lenngrad (USSR) Hydrogen 6.0 MM CF/D 1~2 E 75 HRI HRI TECH SER /KAWASAKI KAWASAKI Wintershall AG Salzbergen (W.Germany) Hydrogen - - U KTI - KTI . Erdol . RI y. . ` Natl. Iranian Tehran (Iran) Hydrogen 33.0 MM CF/D - . E 76 UOP SWAM PROGETT SHAM PROGETT Oil Co. Natl. Iranian Tehran (Iran) Hydrogen 30.5. MM CF/D - U 75 - . .. FLUOR FLUOR Oil Co. . Riyadh Rfy. Riyadh (Saudi Arabia) Hydrogen 15.4 MM CF/D ` - * U 74 UOP CHIYOPA CHIYOPA China Natl. Sheng Yang, Hydrogen 4.5 MM CF/D - P 77 . TECHNIP SPEICHIN/ TEC!~IF SPEICHIM/ TECHNIP Tech. China , - Import A-60 PAGENO="0791" C.n PLANT COMPANY SITE PROJECT CAPACITY ESTIMATED COST MM$ STATUS LICENSOR ENGINEERING CONTRACTOR Asia Kyoseki Co. Ltd. Sakaide (Japan) Hydrogen 22.4 ~4M CF/D - E 75 TO~SOE . CHIYODA CHIYODA . Asia Sakaide Hydrogen - - P - Kyoseki (Japan) - - Co.Ltd. Fuji Chiba Hydrogen 19.0 - U 77 TOPSOE Oil Co. MM CF/D CHIYODA CHIYODA Ltd. Idemitsu Aichi Hydrogen 61.6 - U 75 TOPSOE Kosan (Japan) NM CF/D CHIYODA Co. Ltd. . . . Idemitsu Tokuyama Hydrogen 15.0 - U 74 ICI Kosan Co. (Japan) MM CF/D . IHI ICI Ltd. Idemitsu Kosan Tokuyama (Japan) I~rdrogen 19.0 MM CF/D - U 75 ICI IHI IHI Co. Ltd. Mitsubishi Mizushima Hydrogen 39.0 - U 74 Oil Co. (Japan) MM CF/D TOPSOE CHIYODA CHIYODA Ltd. Nihon Toyama Hydrogen 50.0 - P 77 - Kai Oil (Japan) MN CF/D - Co. Ltd. Nippon Mizushima Hydrogen 29.0 . Mining (Japan) MM CF/D - E . 74 TOPSOE CHIYODA Co. Ltd; CHIYODA Chinese Hsin Chu Hydrogen 50.0 - U 74 TOPSOE PARSONS Petr. Kadhsiung Taiwan MM CF/D . MM PARSONS MM ~~`~~Cor Kwinana ha) Hydrogen ~~CF/D E ~B~LL-D PAGENO="0792" PLANT ESTIMATED COMPANY SITE PROJECT CAPACITY COST MM$ Shell Oil Norco, Hydrogen 2.0 - Co. Louisi- MM CF/D ana I3asf Ludwig- Hydrogen 7.0 T/D Ag shaffen W.Ger- many STATUS LICENSOR ENGINEERING CONTRACTO. U 74 HOWE- HOWE- KELLOGG BAKER BAKER U 74 GERMAN- GERMAN- GERMAN- LINDE LINDE LINDE Bayer Ag Bruns- buttel W.Ger- many Hydrogen -` - U 75 GERMAN- LINDE GERMAN- LINDE GERMAN- LINDE Jeddah Oil Rfy. Jeddah (Saudi Arabia) Hydrogen 6.7 ~ CF D U 74 UOP , ~ CHIYODA , CHEYODA Asia Oil Co. Yoke- hama, Japan Hydrogen 28.0 MM CF/D - E 75. BENFIELD/ ICI DPT LTD/ MKK MKK . Fujo Oil Co. Ltd. Chiba, Japan Hydrogen . 19.0 MN CF/D - U 75 TOPSOE CHIYODA ~ CHIYODA Korea lad, Equipment Puyang- Tang, North Korea Hydrogen 7.0 T/D - U 74 GERMAN- LINDE GERMAN- LINDE SPEICHIM * Of the 38 plants listed above, 35 currently plan to use petroleum products as a feedstock. A-6 2 PAGENO="0793" 787 KEY MNCF/D = MILLIONS OF CUBIC FEET PER DAY T/D = LONG TONS PER DAY MMCF/Y = MILLIONS OF CUBIC FEET PER YEAR STATUS P = PLANNING E = ENGINEERING U UNDER CONSTRUCTION C = COMPLETED = DELETED FROM SUBSEQUENT TABULAT IONS 76 = LAST TWO NUMBERS OF YEAR OF ESTIMATED COMPLETION REFERENCES - TABLES A.3-1, A.3-2 and A.3-3 obtained from: 1. HYDROCARBON PROCESSING (SECTION 2) Pg. 1-39 JUNE 1974 2. Mr. John Gallagher, American Lurgi, New York A-63 PAGENO="0794" 788 of coal to gas conversion was the production of gas which could be used for lighting purposes. In the coal gas production, about 2/3 of the original coal was not utilized, and the remaining carbon and ash residue was sold or burned in the plant elsewhere (Ref. 7). A gas similar in composition to the coal gas is produced when coal is heated in the manufacture of coke. Frequently, the coke oven gas was used to supplement coal gas when it was locally avail- able. In the coke oven gas production, there was no low priced by-product since the remaining solid carbon (coke) was used in the production of steel or cast iron. Typical heating values of coal gas and of coke oven gas ranged from 475 to 575 BTU/CF. A third process of coal gasification was developed in the middle 1800's. This process was the producer gas manufacturing method in which dry air was blown through a bed of coke or coal of sufficient depth to produce a combustible gas consisting prinarily of carbon monoxide and nitrogen at a ratio of about 1 to 2. The heating value of the gas from early producers was only from 100-130 BTU/CF. The heat liberated in the process of producing this gas was much greater than that required to maintain the fuel bed at the desired temperature. As a result, an undesirable side effect was often the formation of fused ash (clinker) in the fuel bed which complicated the operations of the gas producer. Also, much of the potential heat in the fuel left the producer as sensible heat in the gas, and unless the producer gas was used in the plant itself much of the sensible heat was lost. To increase the thermal efficiency and to moderate the temper- ature of the fuel bed, steam was introduced to the blast. This re- sulted in additional generation of fuel gas by the reaction of carbon with steam. The reaction, being endothermic, had the effect o~ reducing the fuel bed temperature and preventing the fusing of the ash. Typical heating value of producer gas made with air-steam A- 64 PAGENO="0795" 789 blasting was from 130 to 160 BTU/CF. The composition of the gas was about 50 percent nitrogen, 25 percent carbon monoxide, 15 per- cent hydrogen, the remainder being carbon dioxide, methane, etc. Since the heating values of carbon monoxide and of hydrogen are only 320 and 310 BTU/CF, respectively, and in order to raise the heating value of the producer gas, nitrogen had to be excluded from the process. This was achieved by two methods. The first method in- volved the alternate preheating of coke by combusting it with air, followed by the generation of a combustible gas using steam only. The second approach involved the use of oxygen rather than air in the gas generation process. In the late nineteenth century the blue gas process was de- veloped in which steam was passed over red hot carbon at a temper- ature from 1750° - 2200°F. The gas thus formed burned with a non- luminous bluish f lane and for this reason it was called `blue gas" or "blue water gas'. Since the basic reaction to produce the blue gas (90 percent of which is carbon monoxide and hydrogen in a pro- portion of about 1 to 1) is endothermic, the temperature of the fuel bed has to be raised periodically from 1750F to 2200 F. This was done by blasting air through the carbon bed raising its temperature to the desired level. After the "blow" period, the air valves were shut off and steam was again passed through the carbon bed genera- ting the blue gas. The heating value of the "blue gas" was about 300 nTU/CF. Most of the town gases distributed throughout the United States cities prior to 1945 had a heating value between 450 and 500 BTU/CF. The blue gas was usually enriched by the addition of light hydro- carbons produced during thermal cracking of heavy fuel oil sprayed on hot bricks. In the early 1920's the use of oxygen and steam (rather than air and steam) was first introduced for coal gasification on a com- mercial scale in the Winkler process. The Winkler coal gasifier is a fluidized bed reactor which operates at near atmospheric con- A- 65 PAGENO="0796" 790 * dition. The second process to use oxygen and steam to produce gas from coal is the Lurgi process, commercially introduced in the 1930's. The Lurgi counter current flow shaft gasifier operates at a pressure from 300 to 400 psi and rejects essentially a carbon free ash (Ref. 8). The third process to use oxygen and steam for coal gasification was the Koppers-Totzek process first tested in 1948. The Koppers- Totzek reactor is a partial pulverized coal cornbustor operated at near atmospheric conditions (Ref. 9,10). Currently there are no Winkler, Lurgi or Koppers-Totzek gasifi- ers operating in the United States. Five Lurgi technology plants for the United States are in engineering study stages, and when built will be used to supply hydrogen and carbon monoxide for-the production of methane (natural gas). In recent years many more coal gasification processes have been proposed and are at different stages of development. None of the new processes, however, are producing gas on a commercial scale (Ref. 11). A.3.2 - Gasification Reactions for Production of Hydrogen All fossil fuel gasification processes produce a gas that is essentially a mixture of hydrogen and carbon oxides with widely different admixtures of nitrogen, steam, hydrogen sulfide, ammonia, methane, other hydrocarbons and other gases. The basic reactions are few and are often identified by a special name. First, we have the thermal cracking reactions: for methane: CH4 + L~ -~ C + 2H2 (la) for other hydrocarbons: CHn + ~ ~ C + ~ H2 (lb) The reactions take place at a temperature above 1600 F and are used in commercial processes to furnish carbon for rubber manufacture and hydrogen for ammonia synthesis. A-66 PAGENO="0797" 791 Methane in the presence of steam and a catalyst produces hy- drogen by the following reaction: CH4+H2O+CO+3H2 (2a) A similar reaction of carbon with steam is the principal reac- tion by which blue water gas is made: C+H2O~CO+H2 (2b) Carbon is converted to carbon oxides by: 2C+02~2cO (3a) C+02÷C02 (3b) 2C0 + 02 -~ 2C02 (3c) Reaction (3a) is the principal mechanism of carbon consump- tion, while (3b) and (3c) are principal exothermic reactions. The water gas shift reaction is an important method by which hydrogen is adjusted to derived concentrations in the final stream. It is usually carried out in two steps in presence of excess steam. CO + H20 CO2 + H~ - (4a) The methanation reaction is used to remove final traces of carbon monoxide from a hydrogen stream when ultra high priority gas is desired, and also is the principal reaction for the production of substitute natural gas (SNG). CO + 3H2 CH4 + H2O (5a) At one time the steam-iron method of hydrogen production was the basis for an important commercial process (patented 1861), success- fully developed about 1900. It is again being seriously looked at for hydrogen production in a continuous process using char (produced in a coal gasification process) for a source of H2 and CO (Ref. 12). A-67 PAGENO="0798" 792 The original method involved the passing of steam over iron heated to about 1200 F. The reaction proceeded according to the equation: 3 Fe + 4 H20 Fe304 + 4 H2 (6a) After a 10 minute hydrogen generation step, the iron oxide was regenerated during a 20 minute cycle using blue water gas: Fe304 + 2 CO + 2H2-'- 3Fe3+ 2 CO2 + 2 H20 (6b) About thirty years ago, this process had widespread use in plants hydrogenerating vegetable oils. A.3.3 - Gas Producers In its simplest form, a gas producer consists of a vertical brick-lined vessel on top of which is a charging hopper and on the bottom of which is a grate with the air and steam blast distributor plates. A diagrammatic sketch of a gas producer is shown in Figure A.3-l (Ref. 6). The fuel bed in the gasifier travels vertically from top to bottom, being consumed in the process of coal gasification. One can divide the bed into a succession of horizontal zones: the ash zone, the combustion (or oxidation) zone, the reduction zone, and the distillation zone. a). The ash zone - extends from the grate upward toward a carbon combustion zone. Air and steam enter as uniformly as possibly over the whole section and move upward through the bed. The air and steam cooled ash is removed by continuously rotating or intermittently moving the grate. Any clinker formed earlier is crushed. The ash is usually dropped into water- sealed troughs. For proper operation, it is most important that the blast distribution is uniform, that no gas channeling occurs, that no significant quantities of carbon remain and that the ash does not fuse. b). The combustion zone - occupies a rather thin (about six inches thick) region in which oxygen reacts with carbon in the fuel. The temperature of this zone may reach about 3000 F. In the bottom of the zone the carbon oxidation product is primar- ily carbon dioxide. Near the top of this zone carbon monoxide is formed. The temperature must be closely controlled to pre- vent the formation of large clinker lumps, by the proper propor- A-6 8 PAGENO="0799" 793 FIGURE A.3-1: DIAGRAM~1ATIC SKETCH OF A GAS PRODUCER WATER VAPOR AIR BLAST INLET A- 69 PAGENO="0800" 794 tioning of steam and air. c). The reduction zone - extends for a distance fron one to five feet, in which the temperature drops from about 2200 F to about 1500 F. Here no significant oxygen remains, most of the carbon dioxide is converted to carbon monoxide and a significant concentration of hydrogen is first noticed. Near the top of the zone no significant gasification of fixed car- bon occurs. d). The distillation zone - is a zone in which the hot gases from below preheat the coal and cause the volatilization and the cracking of the more volatile coal constituents. The character of the products of the distillation zone depends most strongly on the type of coal fed into the gasifier. The producer gas composition is typically: Fuel Composition of gas made, vol.% Caloric Used CO2 02 CO H2 CH4 N2 Value (Btu/ft3) Coke 6.0 - 27.0 12.5 0.6 53.9 132 Coal 6.0 - 26.0 15.0. 2.5 50.5 156 In order to increase the concentration of hydrogen in the stream above the 15 percent level, all the gases present in the streams ex- cept hydrogen nay be adsorbedusing the pressure swing adsorption method. Carbon monoxide nay then be recovered from the desorbed gas stream by the cryogenic method and then subjected to the "water- gas shift" reaction, forming additional hydrogen. Since for each carbon monoxide molecule one molecule of hydrogen is formed, the total amount of hydrogen that can be recovered from the producer gas is about 40 percent. The maximum volume of hydrogen that can be manufactured by the producer method is approximately 30 standard cubic feet per pound of carbon gasified. In 1926 coal gasification (using the producer gas method) reached its peak in the United States. Approximately 15 million tons of coal and coke were gasified that year in some 12,000 gas producers, generating about eight billion cubic feet per day of producer gas. The total heating value of this amount of producer gas was equivalent to the use of about 200,000 barrels of crude oil per day. A-70 PAGENO="0801" 795 At present there is only one gas producer still operating in the United States. This is a ten foot diameter Wellman-Galusha generator located at the Glen-Gary Corporation plant in Shoemakers- ville, Pennsylvania. It produces about 10 million cubic feet/day of gas containing approximately 50 percent nitrogen, 26 percent carbon monoxide, 14 percent hydrogen, and the remainder carbon dioxide, methane and other. At current anthracite prices, including depre- ciation and maintenance of the producer unit, the gas is produced at a cost of about $1.00 per million Btu's (Ref. 13). A3.4 - Lurgi Gasifiers Prior to 1932, all processes for the gasification of coal oper- ated at low pressure (near atmospheric). Through the pioneering work of Lurgi engineers, it was found that, significant reduction in capital and operating costs for the production of town gas from low grade coal could be realized if the coal gasification was conducted at near 400 psi pressure using oxygen rather than air for blasting. (The use of oxygen for gasification was first introduced by Winkler early in the 1920's). A typical Lurgi's gasification plant~ has as its key component the Lurgi Gasifier (Fig. A.3-2). The gasifier is a double walled pressure vessel. The annulus between the walls acts as a steam generator (Ref. 8 Fuel is charged through a lock hopper and is distributed uni- formly throughout the 15 foot diameter bed. The coal lock hopper is operated with two valves. Coal enters from the feeder to the coal lock when the bottom valve on the lock hopper is closed. When the coal lock is filled, the top valve is closed, the coal lock is pressurized and then the lower valve is opened. If the coal tends to cake, a stirrer device is provided. The gas leaves the reactor near the top at temperatures from 700 - 1100 F. A mixture of oxygen and steam are added through the rotating grate at the bottom of the reactor. Ash is removed through a semi- automatic ash lock using locking and emptying valves similar to those used for coal feeding. Because the process is operated under pressure A-71 62-332 0 - 76 - 51 PAGENO="0802" 796 0 FEED COAL FIGURE A. 3-2: LURGI PRESSURE GASIFIER A-72 DRIVE RECYCLE TAR STEAM GAS ~WATER JACKET STEAM + OXYGEN PAGENO="0803" 797 it is of utmost importance that no gas leakage through the valves occurs. Although some repairs on the locks can be made while the unit is operating, in general, the reactor must be shut-down if significant wear of the valve has occurred and pressure cannot be maintained. To assure continued operation of the plant, usually for every three gasifiers needed to meet the full production sched- ule, a fourth unit is added to be ready for emergency operation or for scheduled maintenance. In a proposed SNG Lurqi plant, 30 gas- ifiers will be used to convert about 22,000 tons of coal per day to produce about 250 million cubic feet of product gas, consisting primarily of methane. An additional 3,000 tons of coal will be used to raise steam and provide electrical power (Ref. 14). The consumption and production figures associated with the Lurgi Process for different coals are as follows: (per 1000 CF of raw gas produced) Feed Material Gas Analysis, Vol. % (dry basis) Sub-bituminous Low Volatile Lignite coal coal CO2 C~ H~ CO H2 CH4 N2 31.9 28.2 26.5 0.5 0.3 0.1 17.4 20.6 21.4 36.4 39.6 43.5 13.5 10.5 8.0 0.3 0.8 0.5 Feed Material Feed Streams: Lignite Sub-bituminous Low Volatile coal coal Coal (lbs.) 41 29 22 02 CF 107 140 150 Steam (lbs.) 38 41 44 Feed Water (lbs.) 5 10 13 A- 73 PAGENO="0804" 798 Compounds, lbs. Feed Material Sub-bituminous Low Volatile Lignite coal coal Tar, oil, light naphthat, etc. 3.7 2.7 0.25 Ammonia 0.37 0.31 0.025 Water Vapor 33.6 33.7 32.8 Sulfur Compounds Quantities vary with the sulfur content of coal As shown in the table above, raw gas leaving the gasifier is saturated with steam and contains tar, oil, etc. It is possible to reform the heavy hydrocarbon streams by partial oxidation to hydrogen and carbon monoxide. The crude gas can then be subjected to gas shift conversion to convert the carbon monoxide to hydrogen. Carbon dioxide and the -sulfur compounds are removed by Rectisol wash combined with nitrogen wash. If a high degree of hydrogen pur- ity is desired, the gas may be further subjected to nethanation or cryogenic upgrading. If ammonia, methanol or synthetic natural gas are the final products, the hydrogen need not be purified further. Currently, Lurgi's gasifiers are used in some fourteen installa- tions, the oldest one located near Zeitz, Germany which has been in operation since 1936. The total capacity of Lurgi's gasifiers is now 484 MM CF/D. There is a total of fourteen plants now operating world wide. It should be noted that most of the gasifiers are used primarily to supply town gas. Only the David Khel, Pakistan and the Sasolburg, South Africa plants are used for the production of high purity hydrogen from coal which is used in ammonia synthesis, substi- tute natural gas production, etc. Five very large Lurgi coal gasification plants, by any standard, each about 250 MNCF/D, are in engineering and planning stages in the United States. They are: the El Paso Natural Gas Company and the Western Gasification plants in New Mexico, and the Panhandle Eastern and the Cities Service-Northern Natural Gas plants in Wyoming and the American Natural Gas plant in North Dakota. The plants are de- A- 74 PAGENO="0805" 799 signed to produce substitute natural gas, primarily methane. Al- though the estimated completion date for the El Paso plant is now 1977, since all the necessary permits have not as yet been ob- tained and since the reactor vessels have as yet not been ordered, it is doubtful that the first plant can be started up prior to 1978. The total anticipated cost for the five plants is about 2.5 billion dollars (1974 est.) (Ref. 15). It should be noted, however, that applications for only two plants have been filed at this time with the FPC. A.3.5 - Koppers-Totzek Gasification Process The Koppers-Totzek (K-T) process is relatively new. It was first introduced in Germany in 1948 and a year later in the United States, where a pilot plant operated for two years. The first com- mercial plant was built in Finland in 1952 and presently the process leads in total installed capacity for worldwide coal gasification - 650 MMCF/D (Fig. A.3-3). Since 1952, 85 percent of new synthesis gas capacity via coal gasification has been captured by the K-T process. The gasifier in the K-T process consists of two (or four) spheroidal cones centrally welded together with one central outlet upward for gas removal and a bottom outlet for slag removal. Double walls are used to provide an annulus for cooling water, and also to generate low pressure steam (Fig. A.3-4). The burners are located at the apex of each gasifier cone. Each burner is mounted in line with the opposing set. Coal is con- veyed to the feed screw conveyors by nitrogen. Oxygen and steam are injected with the coal into the gasifier. The combustion and gasification of coal particles is essentially complete by the time they enter the waste heat boiler. Due to the high temperatures in the gasifier 2700-3500F, essentially all liquid and gaseous hydro- carbons, tars, phenols, ammonia, etc. are dissociated and oxidized. The gas leaving the gasifier is at near equilibrium condition. The gas composition is typically: CO -50% CO2 - 5.5% H2. - 33% H20 - 10% A- 75 PAGENO="0806" 700 U- (~) 600 z 0 500 400 a: z 0 I- 0 a 0 a: 0~ 200 I- -j D 100 0 800 FIGURE A.3-3: GROWTH IN USE OF KOPPERS-TOTZEK PROCESS FOR COAL GASIFICATION 950 1955 1960 1965 1970 YEAR A-7 6 PAGENO="0807" 801 FIGURE A. 3-4: KOPPERS - TOTZEK GASIFICATION PROCESS A-7 7 PAGENO="0808" 802 and the remainder being nitrogen, hydrogen sulfide, etc. about half of the ash leaves the bottom of the gasifier as mol- ten slag. The other half leaves the gasifier as fly ash entrained in the raw gas. The gases are cooled and washed in a vertical spray tower to about 95F. The gas washing is followed by other particulate and hydrogen sulfide removal equipment. The particulate and H2S-free gas- es can then be subjected to CO-shift conversion and CO2 removal to produce either pure hydrogen gas or other H2 to CO gas con- bination, depending on what the final gasification and synthesis product is to be. The largest four headed gasifier constructed to date has a max- imum production capability of about 30 MMCF/D of dry gas. Largest two-headed gasifiers have the dry gas production capacity of 20 MMCF/D. Intensive pilot plant work is currently being pursued in Europe to develop a K-Tgasifier which would operate at elevated pressures (from 200-400 psi). (Ref. 19). If successful, the improvements in the reduced capital cost and reduced oxygen demand for coal gasification would make the K-T process very attractive for industrial hydrogen production vis-a-vis a liquid hydrocarbon stean reforming process or any of the other coal gasification routes. A.3.6 - Winkler Gasification Process The Winkler gasification process was deve1op'~d during the 1920's in Germany. It was the first process to use oxygen for coal gasifi- cation. Typically, the generator is a 60 ft. long x 15 ft. diameter vessel, lined with brick along its entire length. (Fig. A.3-5). It has a grate at the bottom through which 90 percent of the blase oxygen and steam are introduced. A water cooled scraper driven by a rotating shaft transfers the ashes on the grate to an opening to the ash pit from which ashes are removed periodically. The fluidized bed is from 4 to 8 feet high. Fresh coal is fed from a feed bunker through water-jacketed screw conveyors located about half way up the reactor vessel. The coal is, therefore, par- A- 78 PAGENO="0809" I. FEED BUNKER 2.GAS GENERATOR 3. WASTE HEAT BOILER 4. MULTICLONES 5.GAS COLLECTOR MAIN 6.WASHER COOLER 7.THEISSEN DISINTEGRATOR 8.GAS HOLDER BROWN COAL CHAR STEAM 17.5 KG/CM2G 1500 MM WG 02 IO% 4000 C DUST WASH LIQUOR ASH FI(URE A.3-5: FLOW DIAGRAM OF THE WINKLER GASIFICATION PROCESS PAGENO="0810" 804 tially volatilized and pyrolyzed before it falls into the flui- dized bed. Typically, ten percent of the blast oxygen and steam are introduced above the fluidized bed to promote the volatilization and pyrolysis process above the fluidized bed. The sensible heat in the gas is recovered by generating steam. Because of the heavy dust and unburned coal loading in the effluent gas stream, cyclone collectors are added prior to the boiler tubes. The collected dry overhead dust may be reused in a service boiler for raising steam or for pre-drying of coal. A typical analysis of the overhead dust may contain up to 50 percent of the carbon fed to the reactor. The composition of a typical gas from lignite gasified in a Winkler generator, falls into the following ranges on dry basis: CO2 - 16 - 24% H2 - 38 - 44% CO - 27 - 42% N2 - 0.5 - 1.5% CH4 - 0.7 - 1.5% H2S - 0.5 - 1.5% The raw gas must be cleaned by similar processes as used in the Lurgi gasification plants. There are 36 Winkler gasifiers in existence today. The feed to the Winkler unit must be a non-caking coal. Lignite or low rank coals are typically used. If it is desired to eliminate significant production of meth- ane, tars or lighter distillates, tuyeres are arranged above the fluidized bed and additional steam and oxygen are injected into the steam. The control of the coal particle diameter is not as critical as it is for the Lurgi process, however, the presence of too many fires results in poor coal utilization efficiency. A-8 0 PAGENO="0811" 805 A.3.7 - Other Coal Gasification Processes Currently there are four additional coal gasification pro- jects in the United States at various advanced pilot plant stages of development. They are: 1. Hygas (IGT/AG1~), 75 T/D pilot plant operating 2. CO2 Acceptor (Consolidation Coal), 40 T/D pilot plant operating 3. Synthane (Bureau of Mines), 70 T/D pilot plant completed. 4. Bi-Gas (Bituminous Coal Research), 120 T/D pilot plant under construction In addition to this there is one pilot plant under construc- tion to produce hydrogen gas by a modified steam-iron method in which the iron oxide is regenerated using the coal char from the Hygas process. Many other coal gasification projects to produce high BTU gas are under study. Since these processes are unlikely to become com- mercial by 1985, they are not reviewed here. There is one low-BTU coal gasification project which has been announced recently and which merits a special comment. This is the Exxon 500 T/D coal gasification plant in Baytown, Texas. The an- nounced principal justification for this plant is to produce low- BTU gas for heating use in the refinery. It is interesting to note that the Exxon refinery in Baytown will be the first oil refinery to obtain substantial fuel heating energy from coal. It also marks the beginning of the introduction of coal into the crude oil refining and petrochemical manufacturing processes. Other low-BTU coal gasification plants which have been announced are planned exclusively for combined cycle electrical generating stations and are not intended to be used for gas manufacturing only. A.3.7.l - Hygas Coal Gasification Process The Hygas gasification process has been in development since 1946. For the first time this year, the plant has operated con- tinuously for morSe than one month and has successfully produced A- 81 PAGENO="0812" 806 SNG. The additional hydrogen needed in the methanation step had to come, however, from a steam reforming plant. The gasifier in the Hygas process is a two stage fluidized bed reactor with a fluidized coal slurry drier. The first stage of the reactor operates at temperature from 1200 - 1400 F, while the second stage operates at 1600-1800 F. Pressure normally is 1000 Psi. In the gasifier, the hydrogen rich gases and steam move counter currently to coal through the two stages (entering at second stage), a gas solid disengaging section and then the coal slurry drier (Fig.A.3-6).The raw gases after purification enter a catalytic methanation reactor. The hydrogen entering the bottom second stage can be generated in several ways namely a steam-oxy- gen char gasifier, a steam-iron IGT gasifier using char or an electrothermal gasifier. Due to high .costs of electrical power, the electrothermal method has been recently abandoned. A continuous steam-iron method is now in development stages, and will not like- ly reach large pilot plant testing until 1976. The steam-oxygen gasifier was to be integrated into the plant in the first quarter of 1974. A.3.7.2 - C02-Acceptor Process for Coal Gasification The C02-Acceptor process is a two fluidized-bed reactor process in which the exothermic reaction of magnesium oxide and calcium oxide with carbon dioxide provides the bulk of the heat needed to sustain the endothermic steam-coal gasification reactions. The calcium and magnesium carbonates (primarily Mg0 Ca Ca3) are con- verted back to the oxides in a fluidized bed regenerator where fuel char is cornbusted with air at about 1870 F. The devolatilization and gasification of coal (lignite) takes place in presence of steam at a temperature of about 1500 F (Fig.A.3-7). A.3.7.3 - Synthane Process for Coal Gasification In the Synthane gas process coal, steam and oxygen first enter a pretreater and then injected into a gasifier reactor. In the pre- A-8.2 PAGENO="0813" 807 RAW GAS OUTLET TO QUENCH, CLEANUP AND METHANATION STEPS ,,/f \\ INLET FOR SLURRY OF CRUSHED COAL-..-... NITROGEN-PRESSURIZED OUTER SHELL ~ \ FLUIDIZED BED IN SLURRY WHICH SLURRY OIL IS I DR1ER VAPORIZED BY RISING- HOT GASES AS COAL DESCENDS HOT GAS RISING INTO DRIER~ (-I_- I GAS-SOLIDS DR1ED COAL FEED I i I DISENGAGING FOR FIRST-STAGE---- HYDROGASIFICATION HYDROGASIFICATION IN COCURRENT FLOW-~ OF GAS AND SOLIDS FIRST- STAGE HYDROGA SIFICAT ION HIGH VELOCITY GAS FROM SECOND-STAGE ---~ 132 MIXES WITH DRIED COAL FEET HOT GAS RISING 7;:;T~ \ INTO FIRST-STAGE CHAR FROM FIRST STAGE FEEDS INTO SECOND--------- - STAGE FLUIDIZED BED 1>HYDROGASIFICATION RISING GASES CONTACT DESCENDING CHAR IN COUNTERCURRENT FLOW ~ HYDROGEN-RICH GAS RISES TO SECOND-STAGE FLUIDIZED BED ~ HYDROGASIFIED CHAR FROM SECOND-STAGE .__- FEEDS INTO STEAM- STEAM-OXYGEN OXYGEN GASIFIER GASIFIER ASH FIGURE A. 3-6: IGT HYGAS PILOT PLANT HYDROGASIFICATION REACTOR A-83 PAGENO="0814" 808 FIGURE A. 3-7: Co2 ACCEPTOR PROCESS FLOW DIAGRAM A-84 AtR GAS PAGENO="0815" 809 treater section, operating at about 750 F, partial devolatiliza- tion of coal occurs. The gasification reactions take place in a fluidized bed reactor. The reactor is operated at temperatures from 1850 F to 1100 F. The highest temperature is near the bottom of the reactor where oxy~'~n and steam enter. Char residue is with- drawn at the bottom of t:~s reactor (Fig. A.3-8). The raw gas is first subjected to separation of particulates in a cyclone collector. The gas is then purified, reacted in a shift converter to adjust the CO and hydrogen ratio, and then con- verted to methane. A.3.7.4 - Bigas Process for Coal Gasification In the Bigas process steam and oxygen are injected near the bottom of the gasification reactor. The temperature at the bottom of the reactor is about 2800 F at which condition slagging of the ashes occurs. Slag is withdrawn at the bottom of the reactor (Fig.A.3-9) The carbon monoxide and hydrogen gases rise upward through the bed into which coal and addition steam are injected. This entrained flow section of the reactor operates between 1400 - 1700 F. The raw product gases and unreacted char leave at the top of the reactor, where the char is separated in a cyclone and returned back to the lower section of the gasifier. The char free gases are cleaned, passed through a shift converter, further purified and then methanated in a catalytic reactor. A.3.8 - Comparison of Various Processes of Coal Gasification At the present time there are two commercial processes which are most widely used for coal gasification. They are the Lurgi and the Koppers-Totzek processes. The two processes, by far, dominate the coal to gas conversion field. The Lurgi process, with all the inherent difficulties of a reactor with a mechanically actuated stirrer and ash removal equip- ment, is presently dominating the town gas and substitute natural gas generation field. In six years the total installed capacity of the Lurgi gasifiers will be in excess of 2000 MMCF/D with some 300 Lurgi gasifiers in the field. A- 85 PAGENO="0816" 810 PIPELINE GI~~S CHAR RESIDUE FIGURE A. 3-8: SYNTHANE PROCESS FOR MAKING PIPELINE GAS FROM COAL A- 86 PAGENO="0817" 811 FIGURE A.3-9: BIGAS PROCESS FOR MAKING PIPELINE GAS FROM COAL A-87 SLAG 62-332 0 - 76 - 52 PAGENO="0818" 812 The technical reasons for the ability of the Lurgi Company to cap- turé a large portion of the future coal to SNG gasification market are as follows: 1. The Lurgi process is the most tested process. Reactors have operated since 1936. 2. Methane and liquid hydrocarbons produced by the Lurgi gasifier constitute about 1/4 to 1/5 of the total energy content of the generated gas. These high BTU content products result in lower capital investment of SNG synthesis gas equipment. 3. The power requirements to produce SNG are lower than for the competing K-T process because the process is operated at a high pressure throughout. 4. Oxygen requirements are significantly lower (about 1/3 less) for the Lurgi process than for the K-T process. The Koppers-Totzek process currently leads the Lurgi process in the total ammonia synthesis gas production from coal by at least a factor of two. The reasons for this are several. First, the K-T process generates essentially. hydrogen and carbon monoxide free of tar, oils and phenols. Therefore, the production of hydrogen from coal is more direct and less clean-up of gases is required than in the processes where devolatilization of coal takes place. Sec- ond, the K-T process can accept a variety of coals or oil base feed stocks. Variations in coal properties do not strongly affect the method of operation of the reactor. Third, the gasifier is simple in operation and does not have any moving metal parts subjected to hot coal gases. The Winkler process does -not currently enjoy wide use. There are 36 generators currently in operation(Ref. 15). The gasifier op- ates well with lignite or coal char which has been devolatilized. The ash fusion temperatures have to be high to prevent clinker ag- glomeration. The turn down ratio of the gasifier unit is rather limited and the plant has to operate within a narrow production range. The carbon gasification efficiency is not as high as for A- 88 PAGENO="0819" 813 the other two processes. The Hygas process developed by IGT is the most advanced meth- od of coal gasification in existence. It is still, however, at least five years from commercialization, unless a market for the char produced in the gasifier is found. Currently, there is a great deal of hope placed on the IGT fludized bed steam-iron meth- od to resolve the problem of char utilization for hydrogen produc- tion. Since the pilot plant will not be operational for two more years, it is doubtful that a large coal gasification plant will be built to produce SNG using the Hygas process. A. similar char utilization and disposal problem has to be faced by the ~yp~hane process which is much further from commer- cialization than the Hygas process. The CO2 Acceptor process has encountered problems in the operation of the gasifier and the generator due to the presence of low melting point tacky lipuids (CaS- CaSO4) which collect fines. The pilot plant has not operated continuously for more than one hour. The primary advantage of the CO2 Acceptor process in that it uses air rather than oxygen. The ~ process will be tested in 1975 in a new pilot plant under construction. A comprehensive comparison study of the Lurgi, Winkler and Koppers-Totzek gasification processes with the intent of deciding on the best ammonia synthesis gas generation process was reported in an Indian government report (Ref. 17). A good description of the new coal gasification processes for SNG production at various stages of development is presented in Reference 11. A.3.9 - Conclusions There are now three commercially proven processes to convert coal, on a large scale, to a hydrogen and carbon monoxide rich gas. They are the Lurgi, Koppers-Totzek and the Winkler processes. The first two processes are almost exclusively used in all new large plants. (see Table A.3-2). The major exception is an air-blown, fluidized bedproducer gas plant being built for Exxon (Carter Oil A- 89 PAGENO="0820" 3-2 - LIST OF COAL GASIFICATION PLANTS UNDER CONSTRUCTION El Paso Natural Gas San Juan Co. ,N.M. Coal Gasifi- cation 288.0 MM CF/D 491.0 5 . 76 LURGI STEARNS -R - Westorn Gasi- fication Burnham, N.M. Coal Gasif i- cation 250.0 MM CF/B 380.0 ~ 5 . . LURGI . FLUOR FLUOR U.S. Bureau of Mines Brucoton, Penna. Coal Gasifi- cation 75.0 T/0 12.0 U 74 BUREAU MINES RUST ENGG RUST ENGG Bitumi- nious Coal Re- search Monroe- villo Coal Gasifi- cation ~..2 T/D 1.2 U 74 - BRAVO BRAVO 120 T/D - U 75 - - Bituminous Homer Coal Coal Re- City,Pa. Gasifi- search cation Carter Oil Co. ~ytown, ~s Coal Gasifi- cation 500 T/D 40.0 ~ 5 76 - McKEE McKEE Panhandle Campbell Coal 250.0 - P LURGI - - Eastern Co., Nyu. Gasifi- cation MM CF/B 0 Techno- Prague, Coal 13.5 - U UNITED IBEG IBEG Export Czecho- Gasifi- MM CF/B CSR slovakia cation 0 Techno- Export Prague, Czeck Coal Gasifi- 68.B MM CF/B - U 74 0 TOPSOS IBEG 0 IBEG CSR cation C ~IFܱNOUS Hungarian Gas Pocs, Hungary Coal Gasifi- 18.0 MM CF/B - CIFUINOUS CIFUINOUS Trust cation PLANT ESTIMATED COMPANY SITE PROJECT CAPACITY COST MN$ STATUS LICENSOR ENGINEERING CONTRACTOO STEARNS-S A- 90 PAGENO="0821" Saibu Fukuoka, Coal 11.4 Gas Co. Japan Gasifi- MM CF/D Ltd. cation COMPANY PLANT SITE PROJECT CAPACITY ESTIMATED COST MM$ * STATUS LICENSOR ENGINEERING CONTRACTORS Hungarian Gas Trust Sopron, Hungary Coal Gasifi- cation 1.8 MM CF.D - E CIFUINDUS CIFUINDUS CIFUINDUS Berlin Gaswerke Berlin W.Gerrnany Coal Gasif i- cation 7.1 MM CF/D - C74 BASF/LURGI LURGI LURGI Berlin Berlin, Coal 38.9 Gaswerke W.Germany Gasifi- MM CF/D cation H.. - p75 - - Dortrnunder Dortmund Coal 27.0 Gaswerke W.Germany Gasif i- cation MM CF/D . - C74 BASF/LURGI . LURGI LURGI Stadtwerke Dortmund Coal - - C BASF/LURGI LURGI LURGI Dortmund W.Germany Gasifi- cation . Gen. Cairo, Coal 1.0 - E UNITED IBEG IBEG Organiza- Egypt Gasifi- MM CF/D tion cation Gas+Elec. General Alex- Coal 42.0 - E75 IBEG IBEG Egyptian andria, Gasifi- MM CF/D Electric Egypt cation Osaka Osaka, Coal 34.0 6.0 U74 ICI DPG LTD/ MKK Gas Japan Gasifi- MM CF/D MKK Co.Ltd. cation Osaka Senboku, Coal 34.3 - E74 - DPT LTD/ MKK Gas Co. Japan Gasif i- MM CF/D MKK Ltd. cation - E74 BGC DPT LTD/ DPG LTD/ MKK MKK A-91 PAGENO="0822" COMPANY PLANT SITE PROJECT CAPACITY COST MM$ STATUS LICENSOR ENGINEERING CONTRACTOB Saibu Saibu, Coal 5.7 .3 U 74 ONIA GEGI ISHII MKK Gas Co. Japan Gasifi- MM CF/D Ltd. cation Tokyo Gas Co. Orson, Japan Coal Gasifi- 30.0 MM CF/D - E 74 RITACHI/ SELAS HITACHI HITACHI Ltd. cation Tokyo Toyoso, Coal 84.0 . E 74 - HITACHI HITACHI Gas Co. Japan Gasifi- MM CF/D Ltd. cation Cogas Prince- Coal 2.5 T/D - C -. - BECHTEL Development ton,N.J. Refiner Co. Old Ben Toledo, Coal 900 T/D 75.0 P 78 - - Coal Corp. Ohio Refiner Turkiye Ankara, Coal 120.0 MT/Y 12.5 E 75 OTTO OTTO OTTO Komur Isletmeleni Turkey Refiner ~ . Co.Espanol Gas SA Valencia, Spain Coal Gasif i- cation 1.8 MM CF/D C CIFUINDUS CIFUINDUS CIFUINDUS Toho Gas Co. Ltd. Sorami, Japan Coal Gasif i- cation 56.0 MM CF/D - U 74 BGC DPG LTD/MKK MKK Cities Ser- vice -Nor- them Nat- Wyoming Coal Gasifi- cation 250 MM CF/D 450 P 79 LURGI - - ul Gas - American Natural Gas North Dakota Coal Gasifi- cation 250 MM CF/D 450 79 , LURGI A-92 PAGENO="0823" 817 Company) in Baytown, Texas. The Lurgi process is used primarily for SNG synthesis gas and for town gas production. The Koppers-Totzek process is used pri- marily for ammonia synthesis gas production. While the first pro- cess produces a high-BTU gas, rich in methane, tars and light oil distillates,the second process has the advantage of generating a relatively pure mixture of carbon monoxide and hydrogen. Further treatment of raw gases and the water-gas shift conversion can pro- duce essentially pure hydrogen gas. On a smaller production scale, the blue water gas method is expected to be reintroduced for the manufacture of hydrogen rich gases. The fluidized bed processes for SNG production, which are currently being developed in the United States, are not ready yet for commercialization. Except for the IGT Hygas process, none of the projects which are currently at pilot plant stage of develop- ment are expected to be ready for commercialization in the near future. In the low-BTU gas production (roughly 50% N2, remainder H2, CO and C02), fluidized bed gasification is expected to be the major new method of producing gas on a large scale. On a smaller scale, gas producers are expected to be reintroduced to American industry. Despite the current high cost of natural gas, naphtha and dis- tillate fuels, some 35 hydrogen manufacturing plants currently planned or under construction will use these fuels ~s feed stocks (Table A.3-l). Only one plant will probably use coal. With all the announced planned activity in coal gasification for SNG production, the major source of SNG until 1980 will be the completed liquid hydrocarbon cracking plants (562 NMCF/D) capacity (Ref. 18) and plants currently under construction (705 MMCF/D ad- ditional capacity by 1975 - Table A.3-3). It appears that despite the relative abundant supply of coal, A-9 3 PAGENO="0824" TABLE A.3-3 - LIST OF SUBSTITUTE NATURAL GAS PLANTS UNDER CONSTRUCTION Saltimore Baltimore ,Substitute 60.0 Gas & Elec. Md. Natural MM CF/I) Gas BASF/LURGI S& H Kellogg COMPANY PLANT SITE PROJECT CAPACITY ESTIMATED COST M~$ STATUS LICENSOR ENGINEERING CONTRACTORS Tuscon Gas&Elec. Co. Tuscon, Arizona Substitute Natural Gas 100.0 NM CF/I) 30.0 E 75 LURGI FLUOR FLUOR Florida Gas Co. Jackson- ville, Fla. Substitute Natural Gas - - P ~ - ~ - - Gasco Inc. Honolulu, Hawaii Substitute Natural Gas 16.0 MM CF/I) - U 74 LURGI PARSONS RN PARSONS RN Central Illinois Light Co. Peoria, Illinois Substitute Natural Gas 60.0 MM CF/I) 16.0 P - ~ - - ~orthern Illinois Gas Co. Morris, Illinois Substitute Natural Gas 184.0 MN CF/I) - U 74 BGC BECHTEL/ W000ALL-D BECHTEL Peoples Gas Light ~ Hill County, Illinois Substitute Natural Gas 160 MM CF/I) 80.0 * U 74 BGC/KELLOGG KELLOGG KELLOGG RPCO Dil Corp. Maryland Baltimore,Substitute Natural Gas 125 MM CF/I) - P 74 - - - 25.0 p S &W A-94 PAGENO="0825" PLANT COMPANY SITE PROJECT CAPACITY Boston Everett, Substitute 40.0 Gas Co. Mass Natural NM CF/D Gas Consumers Marys- Substitute 220.0 150.0 Power ville, Natural MM CF/D Co. Michigan Gas Cities Diamond, Substitute 125.0 - Service Missouri Natural MM CF/D S-G-Inc. Gas Public Linden, Substitute 125.0 - Service N.J. Natural NM CF/D Elec.& Gas Gas South Glouster Substitute 125.0 30.0 Jersey Co., Natural MM CF/D Energy N.J. Gas Co. Brooklyn Brooklyn, Substitute 60.0 24.0 Union N.Y. Natural MM CF/D Gas Gas Northwest Portland, Substitute 100.0 25.0 Natural Oregon Natural MM CF.D Gas Gas Co. Transco Delaware Substitute 250.0 Energy Co. ,Penn. Natural MMCF/D Co. Gas Coastal Corpus Substitute 200 States Christi, Natural MM CF/D Energy Texas Gas ESTIMATED COST MM$ STATUS LICENSOR ENGINEERING CONTRACTORS - C JSG/UOP BADGER BADGER U BGC H&G LUMMUS E 75 BASF/LURGI S & W S & N U74 BGC FW FW E 74 C E LUMMUS LUMMUS FLUOR BGC LUMMUS BGC H&G LURGI FLUOR BASF/LURGI FLUOR BGC PRITCHARD 85.0 E 33.0 P 74 PRITCHARI A- 95 PAGENO="0826" 820 the activity to produce hydrogen rich gases seems to be in the steam reforming of petroleum liquids. The exceptions are the SNG coal gasification plants. The profit on the operation of these plants is guaranteed by the Federal Power Commission. The reason for the lack of investment commitment outside of the utility industry is probably due to the uncertainty surrounding future petroleum cost and availability, as well as the cost and availability of in- vestment capital required for these large plants. A.3.lO - References 1. "Hydrogen, Steam Reforming", Hydrocarbon Processing, p. 222, Sept. 1972. 2. "Hydrogen - Selas Corporation of America", Hydrocarbon Pro- cessin~, p~ 127, Nov. 1973. 3. Modern Ammonia Plants Based on Coal, Printed in Sept. 1968 by Lurgi Gesellschaft fur Warme - und Chemotechnik for MBH. 4. Shreve, R. Norris, The Chemical Process Industries, Chap. 8, pp. 125-131. McGraw Hill Book Co., Inc., N.Y. 1945. 5. "WOrld Wide HPI Construction Boxscore", Hydrocarbon Processing, Feb. 1974. 6. Lyle, Oliver, The Efficient Use of Fuel, Chap. 18, Her Majesty's Stationery Office, London, Eng., 1969. 7. Perry, Harry, "The Gasification of Coal", Scientific American, Vol. 230, No. 3, Mar. 1974, pp. 19-25. 8. Rudolph, P., The Lurgi Process, The Route to SNG from Coal, presented at the Fourth Synthetic Pipeline Gas Symposium, Chicago, Oct. 30 & 31, 1972. 9. Farnsworth, et. al., K-T: Koppers Commercially Proven Coal and Multiple Fuel Gasifier, Presented to the Association of Iron and Steel Engineer's 1974 Annual Convention, Phila. Pa., Apr. 22-24, 1974. 10. Farnsworth, et.al, Utility Gas By The K-T Process, Presented to Electric Power Research Institute, Monterey, Calif., Apr. 8, 1974. 11. Hottel, B.C. and Howard, J.B., New Energy Technology, Some Facts and Assessments", The M.I.T. Press, Cambridge, Mass. 1971. 12. Coal Technology, Key to Clean Ene~gy, Annual Report 1973-74, öffice of Coal Research, U.S. Dept. of Interior. 13. Dammann, R.W., "Gas Producers -- A Revival?, Presented at Penn. State Univ. to the Energy Utilization Conf., Apr. 8-12, 1974. 14. Goodhoim, P.R., "Coal Gasification - An Alternative in Clean Energy Pro6uction", An A.S.M.E. Publication. A-96 PAGENO="0827" 821 15. Personal Communication with Mr. John Gallagher, American Lurgi, N.Y.C. 16. Wall, J.D., "King Coal's Rebirth", Hydrocarbon Prece!~J~, May 1974. 17. Kasturirangan, et.al., Comparative Study of Commercial Coal Gasification Processes -- Koopers-Totzek, Lurgi and Winkler, Koppers Co., Inc., Pittsburgh, Pa. 18. "Outlook for the HPI", Hydrocarbon Processing, May 1974. 19. Personal Communication with Mr. D. Michael Mitsak, Koppers Co., Pittsburgh, Pa. A-97 PAGENO="0828" 822 A.4 - THERMOCHEMICAL HYDROGEN PRODUCTION A.4.1 - Introduction A pronising method for the production of hydrogen under con- sideration is a cyclic thermochemical process in which the energy to separate hydrogen from water is in the form of heat. One method in commercial practice today to separate hydrogen from water is electrolysis. However, electrolysis of water is faced with inherent thermodynamic limitations on the efficiency of initial conversation of thermal to electrical energy. Current conversion efficiencies are in the range 30-40%; while future projections in- dicate 50% as an achieveable goal. This, in addition to an expected maximum realizable electrolytic efficiency of around 85-95% limits the overall efficiency of electrolysis for hydrogen production ex- pected in the future to about 35-50%. This limitation has prompted attempts to find alternate means of producing hydrogen from water by processes that exceed these efficiencies. The decomposition of water may be accomplished in a single, direct chemical reaction. However, this requires extremely high temperatures, greater than 2000°C. Heat sources capable of supply- ing this temperature are not readily available and thus it appears to be an impractical process for hydrogen production. Theoretically, however, by employing a process whereby in a series of two or more chemical reactions water reacts with an inter- mediate to form products that may be thermally decomposed to produce hydrogen and oxygen in separate reaction stages and regenerate the original intermediate compound, hydrogen may be produced from water at much lower temperatures. In this scheme, the thermal energy in nuclear fission reactors and nuclear fusion reactors, and solar and geothermal energy can be made directly available to the separa- tion process. Then with the appropriate selection of a reaction scheme and the proper operating temperatures, this approach may be capable of yielding a higher overall efficiency of conversion of thermal energy and water to hydrogen than the electrical process. A: 98 PAGENO="0829" 823 Nost of the effort in this area has focused on the thermochemical production of hydrogen employing a nuclear heat source. Thus most of the proposed reaction schemes have been strongly coupled to actual or anticipated reactor core coolant exit temperatures. Table A.4-l indicates these temperatures. While thermochemical processes to produce hydrogen are not in operation today, there is extensive research and development work in this area going on around the world. The largest such effort by far is at the Euratom Laboratory at Ispra, Italy, with a project begun in 1969 and presently employing over 50 people. Other present- ly active projects include German efforts at Julich (KFA) and the Univ~rsity of Aachen, and U.S. efforts at Institute of Gas Technology Argonne National Laboratory, Los Alamos National Laboratory, General Electric Company, and General Atomic Company. The current status of these efforts and their ultimate potential will be discussed below. A.4.2 - Physical Principles & Theory Funk and Reinstrom (Ref s. 1,2) analyzed the problem of the en- ergy requirements for producing H2 from water. For any reversible process operated at constant temperature and pressure, the work (W) and heat (Q) requirements to decompose each gram-mole of H20 are: W = Q = T~S where~G and L~S are the Gibbs free energy change and the entropy change per gram-mole of water. Thus for the reaction H2O(2~) -~ H2(g) + ½ 02(g) at 250C and 1 atm. these requirements become (Ref. 3) N = L~G = 56.69 Kcal/g-mole Q = T~S = 11.63 Kcal/g-mole A- 99 PAGENO="0830" TABLE A.4-l: NUCLEAR REACTOR COOLANT TEMPERATURE H 0 0 Reactor Type _______ Boiling-water reactor (BWR) H20 Pressurized-water reactor (PWR) H20 Low-temperature gas-cooled reactor (LTGR) CO2 Boiling-water reactor with superheat (BWR/SH) H20 Liquid-metal fast-breeder reactor (LMFBR) LNa High-temperature gas-cooled reactor (HTGR) He High-temperature gas-cooled reactor (Germany-pebble bed core) He Reactor Core0Coolant Coolant Exit Temp., C 250 - 325 275 - 350 350 - 575 450 - 575 450 - 625 780 - 900 900 - 1000 PAGENO="0831" 825 and the enthalpy change (LiH) for the reaction becomes = 1~G + TLiS = 68.32 Kcal/mole Thus, in. the case of electrolysis at room temperature, most of the energy (83.7%) to produce 112 must come from electric power (i.e., useful work), the other 16.3% being supplied as heat. Electric power requirements can only be reduced by electrolyzing at elevated temperature, thereby increasing T S and lowering G. Funk and Reinstrom's analysis indicated that, in theory, it should be possible to develop multistep processes for which the power requirements are essentially reduced to zero at a technically feasi- ble temperature (lloo0c). Ideally, there would be some elementor compound H, which would react in a two-step process according to one or the other of the following general schemes: Oxide Reactions: 11 + 1120 + MO + 112 (`Low"temperature) MO -~ 11 + ½O2 (`High'temperature) Hydride Reactions: 11 + 1120 11112 + ½O2 ("Low"temperature) MH2 M + ~2 . ("High"temperature) Requiring that the two-step process ~e feasible at temperatures no higher than llOO°C,Funk and Reir.strom made a systematic search of the elements and their monoxides and hydrides. They concluded: "No compounds which could yield an efficient two-step process were found, Furthermore, based on semi-empirical correlations, it ap- pears unlikely that a compound exists, or can be synthesized, which will yield a two-step chemical process superior to water elec- trolysis". In fact they questioned the existence of any process which would have a higher overall efficiency than water electrolysis. (Overall efficiency (~) as defined here is where ~ri~ is the heat of formation (or combustion) of a mole of water from hydrogen and oxygen and Q is the total heat required by the A-lOl PAGENO="0832" 826 overall process to split a mole of water into hydrogen and oxygen. Since water may exist in either the gaseous or liquid state, the heat of combustion of hydrogen depends on the final product state. Consequently, the lower heating value (LHV) for hydrogen corres- ponds to water vapor products, while the higher heating value (HHV) is for liquid water and hence includes the heat of condensation. Most efficiencies are calculated on the basis of the LHV. The total heat required by the overall process, Q, includes the heat necessary for the individual endothermic reactions as well as extra heat needed to supply pumping power, work of separation, miscellaneous losses, etc.) Thus most of the attention has been focused on the development of processes employing three or more steps. In principle, thousands of combinations of multi-component closed-cycle chemical systems exist that might yield a workable thermochemical water-splitting process. In order to effectively select the most promising cycles, it is necessary to develop a series of criteria to screen potential candidate processes. Ideally, these criteria should include the process overall efficiency based on both thermodynamic and kinetic factors, the required maximum temperature of the process and its compatibility with various nuclear reactor or other heat sources, materials compatibility, and ecological and safety constraints. Un- fortunately, efforts to date have primarily been directed towards establishing thermodynamic feasibility of cycles comparatible with various nuclear reactor heat sources. Nevertheless, thermochemical processes for hydrogen production are promising because ,although thermochemical cycles are also Carnot efficiency limited, the ideal overall efficiency of a thermochemical cycle is higher than the equivalent Carnot efficiency of a heat- engine cycle operating between the same temperatures. Also, it may be possible to employ higher temperatures than can be used in a steam-electric generating plant, thus providing more effective use of the thermal energy available from the primary heat source. A-l02 PAGENO="0833" 827 A.4.3 - Current Status of Technology Hydrogen production by thermochemical processes has been the subject of increasing interest the past 5 years. Over forty schemes have been proposed in the literature and there are strong indica- tions that additional, very promising, processes have been developed that will not be published until patents have been received. Cur- rently major studies are underway to find new processes and develop existing schemes at the Euratom facilities in Ispra, Italy; the Nuclear Research Center of Juelich West Germany; Los Alamos Labora- tory; Lawrence Livermore Laboratory; the Institute of Gas Technology; General Atomic; and General Electric Research Laboratories. In order to develop a perspective of the-scope of the various processes reported to date, 22 schemes are shown in Tables A.4-2 to A.4-4. These schemes are discussed in greater detail below. How- ever, it should be noted that these processes are in the early stages of development. As yet, none of these cycles have been proven ex- perimentally, even at the bench scale. Thus extrapolation from the existing data base to estimate process plant cost and overall ef- ficiency is hazardous. A.4.3.l - Halide Processes Many of the proposed processes for the thermochemical production of hydrogen are based on the chemistry of halide compounds. Nine of these schemes are shown in Table A.4-2. The majority of this work is underway at the Euratom facilities in Ispra, Italy (Ref 5. 4,5). The process that has received the most attention is the Mark 1 cycle. This cycle uses compounds of mercury, bromine and calcium. Considerable effort has been devoted towards equilibrium and kinetics measurements of reaction 1 - the hydrolysis of calcium bromide at various temperatures. The chemistry of the reactions of mercurous bromide with hydrobromic acid and the reaction of mercury bromide with calcium hydroxide are also under investigation. The only data previously available in the literature was on the dissociation of mercuric oxide. The Mark 1 cycle has been subjected to a block diagram analysis which resulted in a predicted overall efficiency of 49.3% (LHV). A-103 62-332 0 - 76 - 53 PAGENO="0834" 828 TABLE A.4-2: HALIDE PROCESSES 1. Mark 1 (Euratom) CaBr2 + 21120 Ca(OH)2 + 2HBr 730°C 2HBr + Hg ± HgBr2 + 112 25 0°C HgBr2 + Ca(OH)2 CaBr2 + HgO + 1120 200°C HgO -~ Hg + ½02 600°C 2. Mark lB (Euratom) CaBr2 + 2H20 -~ Ca(OH)2 + 2HBr 730°C 2HBr + Hg2Br -~ 2HgBr2 + H2 120°C HgBr2 + Hg -~ Hg2Br2 1200C HgBr2 + Ca(OH)2 ÷ CaBr2 + HgO + H20 200°C HgO -~ Hg + ½02 600°C 3. Mark 1C (Euratorn) 2 CaBr2 4 1120 -~ 2 Ca (011)2 + 4 HBr 730°C 4HBr + Cu20 -~ 2 CuBr2 H20 + 112 100°C 2 CuBr2 + 2 Ca(OH)2 -~ 2 CuD + 2 CaBr2 + 2H20 100°C 2 CuO ± Cu20 + ½02 900°C 4. Mark iS (Euratom) SrBr2 + H20 -~ SrO ± 2 HBr 800°C 2HBr + Hg -* HgBr2 + 112 200°C SrO + HgBr2 -~ SrBr2 + Hg + ½02 500°C 5. Mark 5 (Euratom) CaBr2 + 1120 + CO2 ÷ CaCO3 + 2HBr 600°C CaCO3 ÷ CaD + CO2 900°C 2IiBr + Hg ÷ HgBr2 + H2 2000C HgBr2 + CaO + nH2O ÷ CaBr2 (aq) + HgO 200°C HgO ÷ Hg + ½02 600°C A-104 PAGENO="0835" 829 6. Mark 7 (Eruatom) 6 FeCL2 + 8 1120 -~ 2 Fe304 + 12 HC~ + 2H2 650°C 2 Fe304 + ½02 + 3 Fe203 350°C 3 Fe203 + 18 HC2. -~ 6 FeC~3 + 9 1120 120°C 6 FeC9~3 6 FeC~2 + 3C~2 420°C 3 1120 + 3Cp2 6 HC2. + 3/202 800°C 7. Mark 8 (Euratom) 6 MnC~2 + 8 H20 2 Mn304 + 12 HC9- + 2H2 700°C 3 Mn30~ + 12 HC9~ -~ 6 MnC9~2 + 3MnO2 + 6 H20 1000C 3 Mn02 Mn304 + 02 9000C 8. Mark 9 (Euratom) 6 FeC22 + 8 H20 2 Fe304 + 12 HC9~ + 2112 650°C 2 Fe304 + 3CZ2 + 12 HC~ 6 FeCZ3 + 6 1120 + 02 150-200°C 6 FeC~3 -~ 6 FeC~2 + 3C92 420°C 9. Agnes (G.E.) 3FeC~2 + 4H20 + Fe304 + 611C9. + 112 450-750°C Fe304 + 8HC~+ FeC~2 + 2FeC~3 + 4H20 100-110°C 2FeC9~3 + 2FeC~2 + C2~ 300°C C2~ + Mg (011)2 + MgC~2 + ½02 + 1120 50 -90°C MgC~2 + 21120 Mg (011)2 + 2HC9~ 350°C A-lOS PAGENO="0836" 830 The Mark 1 process has sone particularly attractive character- istics. Since the maximun temperature required is 730°C the primary nuclear reactor coolant need only be 800-850°C - a tenperature well in the range of actual HTGR's. Also all reaction products are easily separated and all by-products formed can be reinjected at other points in the cycle. However, the Mark 1 cycle is not with- out drawbacks. The use of mercury entails a high inventory cost and presents the possibility of pollution in case of leakage. The use of highly corrosive hydrobromic acid presents problems for construc- tion materials. The above mentioned drawbacks prompted the definition of al- ternative schemes which modify the Mark 1 cycle. The Mark lB dif- fers from the Mark 1 by the reaction between mercury and hydrobromic acid. Realizing this reaction in two steps, as indicated in Table A.4-2, it is possible to decrease the reaction temperature from 2000C to 120°C. This permits a better internal heat recuperation, a higher rate for the reaction, and consequently a lower mercury inventory. Studies are underway on the equilibrium and kinetics of these two reactions. In an attempt to avoid the use of mercury, the Mark 1 was modified (Mark lC) to employ copper instead of mercury. The drawbacks of the Mark lC cycle are in the higher temperature (900°C) necessary to dissociate the copper oxide and in the halved production of hydrogen for the same amount of circulating products as in the mercury cycles. Also a key to the cycle is the second reaction about which little is known. Work is in progress on this reaction at Euratom. Another variation of the Mark 1 cycle, the Mark lS, employs strontium instead of calcium. Besides reducing the cycle to three steps, at the expense of a slightly higher temperature, the major ad- vantage of employing strontium bromide is the possibility, calculated from thermodynamic data, of carrying out the third reaction in the solid-phase. This avoids the manipulation of the concentrated solu- tions of bromides and results in a lower hydrobronic acid concentra- tion. While this process has been patented, the third reaction has as yet not been tested in the laboratory. Obviously, the second reaction in the Hark lS cycle may be replaced by the second and third reactions in the Mark lB cycle. A-106 PAGENO="0837" 831 The Mark 5 cycle employs compounds of carbon, as well as mercury, bromine and calcium. The difference from the Mark 1 is the lower temperature for the hydrolysis reaction. From preliminary tests, for the same hydrobromic acid concentration, a 200°C lowering of temperature in the hydrolysis reaction can be obtained. This lower temperature could help in solving the problem of construction material in the chemical reactor. However, this advantage has to be paid by the higher temperature needed for the dissociation of calcium car- bonate. Tests on the first reaction are in progress. This cycle can also be modified by the introduction of copper instead of mercury (as in Hark 1C) or by performing the reaction between mercury and -hydrobromic acid in two steps (as in Mark 1B). In the study of new cycles to produce hydrogen by decomposing water through a series of chemical reactions, processes based on iron chlorides and manganese chlorides have been proposed. The main characteristics of this family is to use as intermediate compounds, only combinations of iron (manganese), chlorine, oxygen and hydrogen. The Mark 7 cycle is one of the iron-chlorine family; the basic reaction is the hydrolysis of ferrous chloride at high temperature to produce hydrogen. Experimental studies are in progress on this scheme. Two modifications of the Mark 7 have been proposed - Mark 7A and Mark 7B. In the Mark 7A cycle the first three reactions are identical with Mark 7, but some of the Fe203/is chlorinated by chlorine to produce oxygen. This reaction is used in place of reaction five of Mark 7. In the Mark 7E, the first 2 reactions are the same as in Mark 7, but then all the ferric oxide is chlorinated by chlorine, to form anhydrous ferric chloride and oxygen; this chloride is thermally decomposed and HC1 obtained from reaction 1 reacts with some of the oxygen to produce the chlorine necessary for the chlorination of Fe203. The Mark 8 cycle is based on the hydrolysis of manganese chloride. The first reaction has been described in the literature where there is some disagreement about the composition of the manganese oxide obtained. A similar reaction to reaction two, employing sulfuric acid instead of hydrochloric acid, is also described in the litera- ture. The third reaction, while requiring a high temperature, doesn't seem to pose any practical difficulty. Work is planned on A-l07 PAGENO="0838" 832 reactions one and two. The Mark 9 cycle also belongs to the iron-chlorine family, however, it is defined by only 3 reactions. It is built on the hy- drolysis of ferrous chloride. In reaction 2 magnetite is simultane- ously oxidized and chlorinated by a mixture of hydrogen chloride and chlorine with formation of ferric chloride and evolution of oxygen. Experimental work on this reaction has been started. The final halide process listed in Table A.4-2 is the Agnes Process (Ref. 6) proposed by Wentorf and Hanneman at General Electric. In this process iron, chlorine, and nagnesium are cycled through five reactions. This process can operate at relatively low temperatures if necessary, which limits the overall efficiency compared to pro- cesses where heat is available at higher temperatures. On the other hand, at lower temperatures cheaper heat, such as sunshine or partially degraded nuclear heat rejected from another coupled process, can be used and corrosion problems are less severe. This process has been subjected to thermochemical analysis only, and the authors report an overall efficiency of 41% (LHV). A.4.3.2 - Reverse Deacon Processes A series of processes have been developed around the reaction of chlorine gas and water to form hydrochloric acid and oxygen (Table A.4-3). The reverse reaction, the oxidation of hydrochloric acid, has been of commercial interest for almost a hundred years and is known as the Deacon process for chlorine manufacture. By increasing the temperature the equilibrium in the Deacon reaction can be re- versed to produce hydrogen chloride and oxygen. The first cycle uses vanadium chlorides in a four step cycle and was first proposed by Funk and Reimstrom in 1964. Funk calculated an overall efficiency of 18% (HHV) for the process. This figure is lower than most reported efficiencies for other processes, since Funk included the work of separation in his calculations. Other chlorides of the Group V family such as tantalum were considered and foundless promising than vanadium (Ref. 1). A-l08 PAGENO="0839" 833 TABLE A.4-3: REVERSE DEACON PROCESSES 1. Vanadium Chloride Process (Allison Div., G.M.) H20 + C~2 2 HC2. + ½02 800°C 2VCi2 + 2HCZ -~ 2VC~3 + H2 25°C 4 VCj~ -~ 2VC~4 + 2 VC~ 700°C 2 VC~ 2VC~3 + c~ 25°C 2. Mark 3 (Euratom) H20 + CL2 2HC~. + ½O2 8O0~C 2 VOCL + 2 HCP. -~ 2 VOCL2 + H2 170°C 4 VOCL2 2 VOCP. + 2 VOCL3 600°C 2 VOCL3 -~ 2 VOCL2 + CL2 200°C 3. Mark 4 (Euratom) H2O + CL2 -~ 2HCL + ½O2 800°C 2HCL + S + 2 FeCL2 ÷ H2S + 2 FeCL3 100°C H2S H2 + ½S2 800°C 2 FeCL3 ÷ 2 FeCL2 + CL2 420°C 4. Mark 6 (Euratorn) CL2 + H2O ÷ 2HCL + ½02 800°C 2HCL + 2CrCL2 ÷ 2CrCL3 + H2 170°C 2CrCL3 + 2 FeCL2 ÷ 2 CrCL2 + 2FeCL3 700°C 2FeCL3 ÷ 2FeCL2 + CL2 350°C A-lU 9 PAGENO="0840" 834 The Mark 3 cycle proposed by De Beni is similar to the cycle of Funk and Reinstrom, however, the oxichlorides of vanadium are sub- stituted for the vanadium chlorides. This substitution is suggested by the lower affinities of the oxichlorides towards water. The Mark 4 cycle, patented by Hardy, involves the iron chlorides and sulfur. The hydrochloric acid, formed in the reverse Deacon pro- cess, reacts with sulfur and ferrous chloride with oxidation of fer- rous chloride to ferric chloride with the evolution of hydrogen sul- phide. The ferric chloride and hydrogen sulphide are then separate- ly thermally decomposed. There seems to be no current work underway on this process. The Mark 6 cycle is based only on thermodynamic calculations. At the temperatures envisaged for the second reaction the two chromium chlorides are solids and therefore, it is proposed to carry out the reaction in a bath of molten salts. Also, in the third reaction, iron chloride FeCl2 could be substituted for by vanadium chloride VC12. The Mark 6C, a modification of the Hark 6 cycle, employs a copper chloride reaction in a 5 step schema to overcome the eventual diff i- culty of the direct decomposition of the iron trichloride. All the reactions appear quite feasible from the available thermodynamic data, however, no experimental work has been performed to date. A.4.3.3 - Metal Processes A carbon-iron oxide process has been suggested by De Beni and Marchetti (Ref. 7). It is a simple reaction sequence, employing a three step cycle. This process, although thermodynamically feasible, requires a rather high temperature (1425°C). Since this tempera- ture is beyond the range of current nuclear energy heat sources, work at Euratom on this process has stopped. Another carbon-iron process was proposed by C.G. Von Fredersdorff of the Institute of Gas Technology in 1959 (Ref. 8). The heart of the scheme is the production of H2 by the steam-iron process, a process of proven feasibility. However, the proposed process calls for the decomposition of CO2 under conditions that are highly un- favorable thermodynamically. It is proposed to decompose the CO2 to CO in a chemonuclear reactor at 315°C and the major obstacle to the A- 110 PAGENO="0841" 835 TABLE A.4-4: METAL PROCESSES 1. Carbon-Iron Process (Euratorn) C+H2O-~CO+H2 700°C CO + 2 Fe304 -~ C + 3Fe2O3 250°C 3Fe2O3 2Fe3O4 + ½O2 1425°C 2. Carbon Dioxide-Iron Process (IGT) Fe + H2O FeO + H2 3FeO + 1120 Fe3O4 + H2 550- Fe3O4 + CO 3FeO + CO2 950°C FeO + CO -~ Fe + CO2 2C02 2CO + 02 315°C 3. Sulfur Dioxide-Iron Process (IGT) Fe3O4 + 2H2O + 3 502 3 FeSO4 + 2 H2 1250C 3FeSO4 -~ 3/2 Fe2O3 + 3/2 So2 + 3/2 503 725°C 3/2 Fe2O3 + ½ SO2 -~- Fe304 + ½ SO3 925°C 2 SO3 -~ 2 SO2 + 02 925°C 4. Cesium Process (Aerojet) 2Cs + 2H20 -~ 2CsOH + H2 100°C 2CsOH + 3/202 ÷ 1120 + 2CsO2 500°C 2Cso2 ÷ Cs20 + 3/2 02 700°C Cs20 -~ 2Cs + ½O2 1200°C 5. Catherine Process (G.E.) 312 + 6 LiOH ÷ 5 Lil + Li103 + 3H2O 100-190°C LIIO3 + KI ÷ 1<103 + LiI 0°C 1<103 KI + 1.502 6500C 6LiI+ 6H2O ÷ 6H1 + 6LiOH 450-600°C 6H1 + 3 NJ. 3Ni12 + 3112 150°C 3N112 ÷ 3Ni + 312 700°C A-ill PAGENO="0842" 836 6. Lithium Nitrate Process (Argonne Nat. Labs) LjNO2 + 12 + H20 -~ L1NO3 + 2H1 25°C 2H1÷H2+12 425°C LiNO3 -~ LINO2 ± ½02 425°C 7. Tin Oxide Process (Gaz de France) Sn + 2H20 -~ 2H2 + Sn02 400°C 2 Sn02 -~ 2 SnO + 02 1700°C 2 SnO -~ Sn02 + Sn 700°C 8. Beulah Process (G.E.) 2 Cu + 2HC2~-~- H2 + 2 CuC2. 100°C 4 CuCI÷ 2 CuCZ2 + 2 Cu 30-100°C 2 CuCi2 2 CuCL + C5~2 500-600°C Ci2 + Mg(OH)2 ± MgC2~2 ± H20 + ½02 80°C MgCI2 + 2H20 ± Mg (OH)2 + 2HCZ 350°C 9. Mark 2 (Euratom) Mn203 + 4 NaOH ± 2 Na20 Nn02 + H20 + H2 800°C 2 Na2O . Mn02 + nH2O ± 4 NaOH(aq) + 2 Mn02 100°C 2 MnO2 ÷ Mn203 + ½02 600°C A-112 PAGENO="0843" 837 development of this process will be the development of the chemonuclear reactor itself. Another process developed at the Institute of Gas Technology involving iron oxides and iron sulf ides emplpys sulfur dioxide in a four step scheme. This process has considerable merit, however a potential problem nay be the relatively high maximum temperature re- quired (925°C). Further developments with the HTGR may increase the attractiveness of this cycle. A process employing cesium and cesium oxides was patented by Miller and Jaffe in 1970 (Ref. 9). No experimental work was reported in the patent description. De Beni and Marchetti (Ref. 4) calculated, from available thermodynamic data, quite an unfavorable equilibrium constant for reaction 2. Consequently, in addition to the maximum high temperature required (1200°C), this process would result in a considerable expenditure of work for. separation and recirculation. A small family of processes based on iodine exist. One such pro- cess, Catherine, is proposed by Wentorf and Hanneman (Ref. 6) at General Electric. It consists of six steps as shown. Reaction 1 is quite rapid at 80°F, but the authors propose to allow it to run at 100° to l900C so as to use the heat to evaporate liquid in other steps. Since iodine does not liberate oxygen directly from water in alkaline solution as does chlorine and bromine, the production of oxygen from iodine requires several steps. Also, it will be necessary to avoid undesired oxidation of iodide by excluding oxgyen in certain steps of the process. The authors calculate an overall efficiency of 64% (LHV) for the Catherine process. Another process involving iodine has been suggested by Abraham and Schreiner (Ref. 10) at Argonne National Laboratories. It is a three step scheme which requires moderately low temperatures. The first reaction has not bean tested, however since it is similar to the well studied oxidation of sulfurous acid by iodine to form hy- drogen iodide and the sulfate ion, it is expected to go as indicated. The second and third reactions are well known. ~A-ll3 PAGENO="0844" 838 A metal oxide process, based on tin, was suggested by Souriau in 1972 (Ref. 11). The author claims an overall efficiency of 36% (LHV) for this process, however a very serious drawback of this process is the extremely high tenperature (1700°C) required for the second reaction. The author suggests that the temperature required for the decomposition of tin oxide be obtained fron a nuclear heat source. This is impossible for current reactors. Another process suggested by Wentorf and Hanneman at General Electric is the Beulah Process. In this process copper, chlorine, and magnesium are cycled through five basic steps. The last two steps are the same as used in the Agnes process for producing HC1 and 02 fron Cl2 and H20. A simplified flow chart for the Beulah Pro- cess has been developed and the authors calculate overall efficiency of 57% (LHV). The Beulah Process has a higher efficiency than the Agnes process because it operates at a higher maximum temperature and less heat is circulated internally. The final process to be discussed is the Mark 2 processes pro- posed by De Beni. It Is a three step cycle as shown. However, pre- liminary results from an experimental study of reaction one were not satisfactory. Consequently, work was stopped on this cycle to al- low concentration on more promising schemes. A.4.4 - Comparative Evaluation of Current Processes It is premature at this point to attempt a rigorous comparative evaluation of the more than forty schemes proposed in the literature. In the first place, as indicated in the previous section, many of the suggested schemes are still in the conceptual stage. In other instances, experimental investigations of the equilibrium and kine- tics of the various reactions are still in progress. Thus the de- gree of knowledge of the chemistry cf the reactions is quite spread. And as the experimental work continues, it becomes more and more clear that existing thermodynamic data on many of these compounds are inadequate. Yields less than 10% the theoretical amount have been obtained (Ref. 5). A-1l4 PAGENO="0845" 839 In addition to the lack of information on the yields and kinetics of reactions in currently proposed processes, new, and potentially better, schemes are under development. Hence the most promising thermochemical scheme may not have been proposed as yet. Nevertheless, some general guidelines can be suggested when evalu- ating various processes. In general, the higher the highest heat input temperature, the higher the thermochemical efficiency. Since the capital costs and work of separation and recirculation will general- ly increase with the number of reactions in the process (proposed cycles generally have 3 to 5 reactions) the number of reactions in the process should be kept to a minimum (3 if possible). Also due to increased material and equipment costs, the use of highly corrosive materials should be avoided. Finally, the maximum temperature in the cycle should not exceed the temperatures from currently (or pro- jected) available heat sources. A.4.5 - Ultimate Potential Hydrogen production by thermochemical processes employing nuclear heat sources has excellent potential to meet future hydrogen demands. While the majority of thermochemical cycles proposed to date are only. in the early stages of development, the number of potential cycles is almost unlimited (Ref. 12). This approach is aimed at competing with the electrolysis of water, since it employs nuclear heat as the primary energy source and water as the feedstock. The major advantage of thermochemical hydrogen production over electrolysis lies in the inherent potential of increased efficiency of conversion. And present indications are that there exists sufficient incentives for further development of thermochemical cycles. For example, recent studies have shown that high temperature (>1200°C) thermochemistry may be 20% more efficient than electrolysis, but at low temperatures (<650°C) this advantage is doubtful at best (Ref. 13). Nevertheless, even a few percent advantage would justify a considerable amount of research and devel- opment effort in this area. A-1l5 PAGENO="0846" 840 The higher the maximum temperatures achieved in nuclear reactors, the greater the potential for nuclear water-splitting. Currently, the highest temperature nuclear heat available is from the HTGR's. However, nuclear reactors have been developed that operate at higher temperatures than HTGR's. The nuclear rocket propulsion reactors, developed in the Rover program, were designed and operated to heat hydrogen to temperatures around 23000C for 10 hours (Ref. 14). And the UHTREX reactor was designed to heat helium to 1320°C and operate at fuel temperatures in excess of 1650°C for 30 days prior to project cancellation (Ref. 14). Both reactors used the sane fuel technology (pyrocarbon-coated UC2 beads) as the HTGR, but the core geometries were more finely divided, providing for smaller temperature differ- ences between the fuel and the coolant. Thus; it is reasonable to expect, that with further fuel-technology development and with a different reactor core design, an HTGR type reactor could be developed to heat helium to higher temperatures. Since the choice of any given cycle is dependent a priori upon the availability of a heating fluid at a high enough temperature to supply heat to the endothermic reactions required, as the tempera- ture of the heating fluid increases, not only does the efficiency of the reaction increase, but also the temperature range for possi- ble additional cycles is extended. This allows a change in the cheni- cal elements involved. None of the proposed processes have been developed to the point where reliable cost estimates can be made. However, two sources indicate a hydrogen production cost of around $l.70/1O6BTU (Ref. 14, 15). One word of caution regarding the production of hydrogen from nuclear heat. `If all the transportation needs in the year 2000, i.e., automobile, air transportation, commercial and urban vehicles, and maritime, were to be satisfied by nuclear hydrogen it would be necessary to increase the projected nuclear electrical generating capacity by a factor of 2.0, which would represent a total invest- ment in excess of $500 x l0~. Obviously, it is unlikely that nuclear energy could be implemented to the required level at least not without A-ll6 PAGENO="0847" 841 great effort, in the required time period' (Ref. 16). Fortunately, thermochemical hydrogen production need not solely rely on heat fron nuclear fission, but may also employ solar, geothermal and (when developed) fusion energy. A.4.6 - Research and Development Needs Processes proposed to date are still at the stage of requiring further laboratory research to establish feasibility, yields and reaction kinetics. Since these processes are still in the proving stage, it is difficult to define a research and development program required to advance them to commercial practice. Clearly, however, a program should be established to yield a definitive evaluation of the potential of thermochemical hydrogen production. This program should include: 1. A continuing effort to develop new thermochemical schemes. Efforts here should include processes compatible with future higher temperature heat sources. 2. The development of criteria to screen existing and future proposed schemes. 3. An examination of existing thermodynamic data. Information to date indicates that some of the available data is inadequate, and it will be neces- sary to generate new thermodynamic and kinetic data for some classes of compounds to permit re- liable evaluation of process feasibility and efficiency. 4. Greater attention to the potential of combined processes, e.g., chemical-electrolytic, for in- creased efficiency. 5. The development of thermochemical hydrogen pro- duction is coupled with the development of a sizable high-temperature primary energy industry. Therefore,, fabrication techniques for fuel ele- ments in nuclear reactors should be investigated A-ll7 PAGENO="0848" 842 with the objective of designing a reactor core with a lower temperature difference between fuel material and coolant than is currently achieved (200-400°C). 6. An investigation as to whether or not there exists the possibility of using the helium fron the nuclear reaction directly in the hydrogen production unit. With this aim in view it will be necessary to esti- mate, in the context of a safety analysis, what constitutes the risks and consequences of the pos- sible poisoning of the helium, following conceiv- able accidents in the plant. - 7. A study of the design problems associated with a heat exchanger in a nuclear reactor-thermochemical system. Most likely it will not be possible to use the helium directly in the process and consequently the interface between the nuclear reactor and the water-splitting process will be a heat exchanger. Major areas where answers will need to be supplied to the nuclear reactor designers are: a) Process fluid - what effect will it have on the heat exchanger materials (primarily con- cerned about corrosion). b) Radiation stability of process fluid - since the fluid will not pass through the reactor core, and heat exchangers can be shielded by the concrete pressure vessel, neution activa- tion will not be a problem. However, gamma radiation can deposit on the heat exchanger via particles carried by the helium from the core. c) Leaks - the consequences of a leak in the heat exchanger must be considered. * d) Catalyst - if a catalyst is required for the process it may have a strong effect on the design of the heat exchanger, primarily be- cause of removability or regeneration requirements. A- 118 PAGENO="0849" 843 e). Range of usable temperature for the process this range establishes the core inlet tempera- ture, which has a strong influence on the usa- bility of present designs and materials. If the core inlet temperature should rise appreciably, say 100-150°C above present values, then current thermal barrier parts, circulator parts,. con- trol rod drives, etc. must be redesigned and made of different materials. A.4.7 - References 1. Funk, J. E. and Reinstrom, R.M., "System Study of Hydrogen Genera- tion by Thermal Energy", Vol. 2, Supplement A, of "Energy Depot Electrolysis Systems Study", Final Report T1D20441, Allison Division of General Motors Report EDR 3714. Washington D.C.; U.S. Atomic Energy Commission, June l96~T 2. Funk, J.E. and Reinstrom, R.M., "Energy Requirements in the Production of Hydrogen From Water', I & EC Process Design Development 5, 336-342, July 1966. 3. NBS Circular 500 `Selected Values of Chemical Thermodynamic Properties" Feb. 1, 1952. 4. De Beni, G. and Marchetti, C., "Mark 1, a Chemical Process to Decompose Water Using Nuclear Heat", Symposium on Non-Fossil Chemical Fuels, ACS 163rd National Meeting, Boston, Mass. April 10-14, 1972. 5. "Hydrogen Production From Water Using Nuclear Heat" ,Report No. 3, EUR/C-I5/35/7 3e. 6. Wentorf, R.H. and Hanneman, R.E., "Thermochemical Hydrogen Generation', General Electric Company Corporate Research and Development Report No. 73CRD222, July 1973. 7. De Beni, G. and Narchetti, C., "Hydrogen, Key to the Energy Market", Euro Spectra, vol. 9, No. 2, pp 46-50, June 1970. 8. Von Fredersdorff, C.G., "Conceptual Process for Hydrogen and Oxygen Production From Nuclear Decomposition of Carbon Dioxide", Memorandum to Project 5-128 Sponsors' Committee, Chicago: Institute of Gas Technology, October 30, 1959. 9. Miller, A.R. and Jaffe, H., "Process for Producing Hydrogen from Water using An Alkali Metal", U.S. Pat. 3.490.871, January 20, 1970. A-119 62-332 0 - 76 - 54 PAGENO="0850" 844 10. Abraham, B.M. and Schreiner, F., "A Low Temperature Thermal Process f or the Decomposition of Water", Science, Vol. 180, P. 959. 1973. 11. Souriau, D., "Utilization of the Heat Energy of Nuclear Reactors', German Pat. 2.221.509, November 16, 1972. 12. Russell, J.L. and Porter, J.T., "A Search For Thermochemical Water-Splitting Cycles, Paper presented at The Hydrogen Economy Miami Energy Conference, March 18-20, 1974, Miami Florida. 13. Gregory, D.P., Institute of Gas Technology, Chicago, Ill. Private Communication, July 1974. 14. Booth, L.A. and Balconib, J.D., "Nuclear Heat and Hydrogen in Future Energy Utilization" Los Alamos informal report LA-5456- MS, Los Alamos Scientific Laboratory, Los Alamos, New Mexico, November, 1973. 15. Russel, J. "Nuclear Water-Splitting and The Hydrogen Economy" Preprint of a paper to be published in Power Engineerin~. General Atomic Company - GA-A12893, Feb. 1, 1974. 16. Sevian, W.A., Salzano, F.J. and Hoffman, K.C., "Analysis of Hydrogen Eflergy Systems" Report to subgroup on synthetic fuels, Office of Science and Technology, BNL 50393, Feb. 1973. A- 120 PAGENO="0851" 845 A. 5 - SUMMARY Perhaps the most important single factor influencing the large scale use of hydrogen resides in the production system. It must be competitive to alternate, clean energy media, both in terms of the costs and the impact on the use of resources and the environment. Clearly, our decreasing natural gas and crude oil reserves indicate that we cannot afford to continue producing hydrogen by the current practice of steam reforming methane and naptha, even to just meet the growing needs for use in ammonia produc- tion, oil refining, methanol production, etc. Appendix A dis- cussed three options for the production of hydrogen: electrolysis, coal gasification, and thermochemical decomposition of water. Effort was directed towards determining the current status of technology, ultimate potential and inherent technological problems associated with these approaches. A summary for each of the hydrogen generation methods follows below. Electrolysis Production of hydrogen by electrolysis is the simplest and cleanest method for making hydrogen from water. Am electrolytic cell operates with essentially no moving parts, can be designed to produce no by-products, and offers the physical separation of hy- drogen and oxygen as well as the initial decomposition of water. In principle, cells can be operated at high pressure with no ef- ficiency penalty, so that electrolysis also represents the most energy-conservative means of developing pressure in the hydrogen product. Several large electrolytic hydrogen plants, consuming upward of 100MW, have been constructed and have operated successfully, while many thousands of smaller units are in use for special ap- plications. However, because its primary energy source, electric power, is expensive and is only obtained at low efficiency (33- 40%) from other energy sources, electrolysis is not a major process for hydrogen production. A- 121 PAGENO="0852" 846 The electrolytic process itself normally operates at effici- encies in the 60-75% range and at capital losts only a fraction (1/5 to 1/3) of the cost of the power station needed to drive it. Since electrolytic-hydrogen costs are dominated by electric- power costs, large electrolysis plants are located only where there is an abundance of cheap hydroelectric power. These plants have been optimized for low capital costs and normally operate at efficiencies lower than can readily be achieved in practice. With the increase in power costs, more effort is being expended to develop the high efficiency potential of electrolysis. Present manufacturers anticipate an increase of overall electrolyzer ef- ficiency to the 77-98% range within the next five years. However, various people and companies have considerably diverging opinions on the most favorable design concepts and technical approaches for electrolyzer construction, and there is no single type of electroly- zer that is universally held as superior. Electrolytic production of hydrogen is an already achieved commercial process that can be improved considerably, both in capi- tal cost requirements and in energy efficiency, by appropriate research. It appears that the various design philosophies proposed to date could result in hydrogen-generation techniques quite dif- ferent in concept from each other, yet all of industrial signif i- cance in appropriate applications. Coal Gasification Coal gasification originated in the late 18th century. For about 150 years, it was a major source of town gas, industrial heating gas and of petrochemicals. The availability of natural gas at very low prices throughout the urban areas after World War II forced the closing of all but one coal gasification plant. Coal, however, remains the fossil fuel of the future. The reason for this is its abundant supply which will last in the United States for at least 200 years. The other fossil fuels will be essentially depleted within 50 years. A- 122 PAGENO="0853" 847 There are two major processes of coal gasification currently used commercially: the Lurgi and the Koppers-Totzek processes. None of these processes are currently used in the United States but are well proven in many installations worldwide. Within the next seven years, the Lurgi process is planned to be used in five coal to SNG gasification plants costing about 2.5 billion dollars. Hydrogen and carbon monoxide rich gases produced from coal will be converted in methanators to yield about 1.5 x 10 cubic feet per day of substitute natural gas. The Koppers- Totzek process is currently the preferred gasification process in applications when only hydrogen is required. New processes of coal gasification are not expected within the next five years to make substantial changes in the presently used techniques of coal gasification. Future technology is moving towards a fluidized bed, high pressure gasification method. Current preferred practice in production of hydrogen is steam reforming of petroleum products. The increases in the prices of crude oil and natural gas have not changed this practice. Un- certainties in cost and supply of capital and fuel stocks are apparently delaying a more extensive use of coal gasification by industry at large, with the exception of gas utilities where pro- fits are guaranteed by the Federal Power Commission Thermochemical Decomposition of Water The decomposition of water may be accomplished in a single, direct chemical reaction. However, this requires extremely high temperatures, greater than 2000°C. Heat sources capable of supply- ing this temperature are not readily available and thus it appears to be. an impractical process for hydrogen production. Theoretical- ly, however, by employing a process whereby in a series of two or more chemical reactions water reacts with an intermediate to form products that may be thermally decomposed to produce hydrogen and oxygen in separate reaction stages and regenerate the original A-l23 PAGENO="0854" 848 intermediate compound, hydrogen nay be produced from water at much lower temperatures. In this scheme, the thermal energy in nuclear fussion reactors and nuclear fusion reactors, and solar and geo- thermal energy can be made directly available to the separation process. While thermochemical processes to produce hydrogen are not in operation today, there is extensive research and development work in this area going on around the world. Most of this effort has focused on the thermochemical production of hydrogen employing a nuclear heat source. In principle, thousands of combinations of multi-component closed-cycle chemical systems exist that might yield a workable thermochemical water-splitting process. Over forty schemes have been proposed in the literature to date, and there are strong in- dications that additional, very promising, processes have been de- veloped that v/ill not be published until patents have been received. Processes proposed to date are still at the stage of requiring further laboratory research to establish feasibility, yields and reaction kinetics. As yet, none of these cycles have been proven experimentally, even at the bench scale. Thus, it is difficult to define a research and development program required to advance them to commercial practice. - Nevertheless, present indications are that - there exists sufficient incentives for further development of thermo- chemical cycles and therefore, a program should be established to yield a definitive evaluation of the potential of thermochemical hydrogen production. A-l2 4 PAGENO="0855" 849 APPENDIX B - HYDROGEN PIPELINE TRANSMISSION ABSTRACT En this study, a brief review of the natural gas trans- mission system is given and then the feasibility of utilizing regenerative turbomachinery as booster compressors on hydrogen transmission pipelines is examined. Requirements for hydrogen pipeline compressors extended as presently existing from the natural gas industry are examined. Performance factors, and problems of application are discussed and a review of regen- erative turbomachinery literature is given. Technical problems which will arise when regenerative turbomachines are used to compress hydrogen gas are discussed and the possible solutions and design approaches which can be taken to overcome them are reviewed. An overall summary is provided of the state-of-the- art of regenerative turbomachinery. B-i PAGENO="0856" 850 APPENDIX B - HYDROGEN PIPELINE TRANSMISSION B.i - INTRODUCTION B-i B.2 - NATURAL GAS TRANSMISSION B-I B.2.i - References B-2 B.3 - PIPELINE COMPRESSORS B-3 B.3.1 - References B-S B.4 - HYDROGEN TRANSMISSION B-S B.4.l - References B-8 B.5 - REGENERATIVE COMPRESSORS B-il B.5.l - Literature Review B-iS B.5.2 - Technical Problens B-.19 B.5.3 - Possible Solutions; Design Approaches & RecommendatiOflsBl9 B.5.4 - References B-21 B.6 - SUMMARY B-23 B-u PAGENO="0857" 851 APPENDIX B HYDROGEN PIPELINE TRANSMISSION B.]. - INTRODUCTION It has been suggested that the natural gas pipeline system be employed for the transmission of hydrogen over long distance in this country (Ref.l, pq.B-2).Due to unique properties, prob- lems in two broad categories are visualized if hydrogen were introduced. The first is the potential weakening of the pipe- line itself due to hydrogen "enthrittlement", especially at those locations where existing stress concentrations create the condition of plastic (as opposed to elastic deformation). This is not the subject of this report. - - - The second is the adverse effect on the existing pumping station machinery, both in performance insofar as ability to produce a sufficient pressure increase and flow rate in an efficient manner as well as operating lifetime; this is the issue considered herein. The existing pumping station compressors--reciprocal in the older ones and centrifugal in the newer--are examined from the viewpoint of their expected performance with hydrogen vis-a-vis natural gas, and potential problems are identified in detail. The potential of a third type of compressor--a re- generative' compressor is examined for hydrogen pipelines. It is concluded that it could be far superior to the other two assuming that its efficiency and capacity can be increased beyond that demonstrated to date. 13.2 - NATURAL GAS TRANSMISSION The natural gas transmission system in the United States comprised in 1970 some 914,830 miles of pipeline carrying 63.8 x lO~ cu.ft./day of gas, representing an annual energy content of 23.34 x 1015 BTU. This energy distribution system served some 41,427,000 customers (op.cit.). A typical transmission pipeline is of the order of 36 inches in diameter and contains natural gas at 1000 psi and 60 0F, compressor stations are lo- cated approximately every 65 miles along the pipeline to boost the line pressure back up to 1000 psi from the 750 psi level B-l PAGENO="0858" 852 typical of the inlet pressure at the station. A conpressor station may handle on the order of 500,000,000 cu.ft./day of natural gas. The pumping machinery used in compressor stations has been multi-cylinder reciprocating compressors driven by natural gas engines. This type of machinery has been sup- planted in recent years by two-stage centrifugal conpressors driven by gas turbine engines/expanders. The reasons for this will be discussed further in a later section. The composition of natural gas from various locations in the United States is shown in Table B.2-l taken from Ref. 2 the principal component is seen to be methane. Of interest to note is the wide variation in composition of natural gas from different locations. Comparison of properties of methane with those of hydrogen appears in table B.4-1. TABLE B.2-I - COMPOSITION OF NATURAL GAS AT WELLS Location Methane Ethane Higher HC Nitrogen CO2 Other Alaska 98.9 0.2 --- 0.7 0.1 0.1 California 82.4 7.7 8.6 0.5 0.8 Colorado 68.0 7.2 5.9 18.2 0.1 0.6 Kansas 78.1 6.1 5.0 10.0 0.2 0.6 Montana 79.9 8.5 4.6 4.5 2.3 0.2 New Mexico 72.9 11.0 12.1 3.5 0.2 0.3 Ohio 86.8 5.9 3.3 3.6 0.2 0.2 Oklahoma 85.0 6.7 6.4 1.5 0.2 0.2 Pennsylvania 97.1 2.0 0.1 0.5 0.1 0.2 Texas 81.6 6.5 3.8 7.7 0.1 0.3 Texas 91.8 4.5 1.8 0.5 1.3 0.1 Utah 42.0 8.0 7.5 15.2 25.8 1.5 West Virginia 75.3 14.2 9.3 0.8 0.2 0.2 Wyoming 86.2 7.8 4.1 0.3 1.5 0.1 Australia 95.6 0.3 1.4 0.8 2.0 Canada 88.5 2.5 2.6 6.2 0.2 Venezuela 73.7 13.8 10.3 --- 2.2 Transmission Line Linden, N.J. 94.5 3.3 1.2 0.3 0.7 B.2.1 References 1. Savage, R.L.,etal,editOrs "A Hydrogen Energy Carrier", Vol. II Systems Analysis, 1973 NASA-ASEE, NASA Grant NGT 44-005-114. 2. Gibbs, C.W.,Ed, `Compressed Air and Gas Data" Ingersoll-Rand Co., N.Y., 1969 B- 2 PAGENO="0859" 853 B.3 - PIPELINE COMPRESSORS Before an appropriate compressor type can be selected for a particular application, certain basic information relating to its performance requirements should be at hand. This in- cludes: pressure ratio, flow rate, efficiencies desired, and could include other special characteristics, as for instance avoidance of pulsations or gas contamination by lubricants. Long life and low maintenance requirements (especially at remote stations) are also usually desirable. One can then consider the type of machine desired from the range of types of com- pressors available, shown in Figure B.3.l. In this figure is shown the division of compressor types into th5e two broad categories of positive displacement machines which increase the pressure of a gas by confining it in a decreasing volume, and dynamic machines which operate by imparting kinetic energy to the gas which. is then converted into pressure rise by diffusion. These latter machines utilize one or more rotating impellers and diffusor passages to achieve this. Not shown in this figure are devices which raise the pressure of a gas by mixing it with a previously pressurized modium. (ejectors). Further differentia- tion of compressor types is also given in the figure. B- 3 PAGENO="0860" 854 FIGURE B.3-1: COMPRESSOR TYPES B-4 PAGENO="0861" 855 One common way to categorize compressors as an aid to se- lection for a given application is in accordance with the spe- cific speed, N5, which combines the pressure ratio, capacity and a characteristic speed into a dimensional grouping as follows: 4/, NY~ 1 (B.3.l) where N = characteristic speed Q = capacity H = pressure rise On this basis the range of compressor types proceeds from positive displacement compressors, at low spedific speed, through centrifugal and on to axial flow compressors at high specific speed. By examining the efficiency variation with, specific speed for each type of compressor, a rational partial selection within overlapping ranges of specific speed may be made. It should be noted that this parameter (N5) is most meaningful when applied to dynamic machines. Further compressor types can be found in Ref- erences 1-3. Information on a more detailed discussion of effi- ciency - specific speed variations for centrifugal machines appears in a later section of this report. B.3.l References 1. Chlumsky, V., `Reciprocating and Rotary Compressors", E.&F.N. Spon Ltd, London, 1965. 2. Wislecenus, G.F., "Fluid Dynamics of Turbomachinery, Dover; 1965 3. Vavra, N.H. "Aerothermodynamics and Flow in Turbomachines, John Wiley, N.Y., 1960. B.4 - HYDROGEN TR7~NSMISSION Before examining the' question of hydrogen pipeline trans~ mission and the related conpressor requirements, it will be illumi- nating to examine the types of machines now used in natural gas transmission. At present in the natural gas industry two major types of compressors are used to boost the pressure along the pipe lines. These are reciprocating compressors (piston type) and centrifugal compressors. The latter machines have largely supplanted the B- 5 PAGENO="0862" 85~ former in pipeline service, due to the following reasons: a. An increase of capacity of pipeline systems and steadier operating conditions which led to: b. Lower pressure ratios and closer spaced compressor stations. Following this: c. Lower initial cost and maintenance expense were ex- perienced for centrifugal compressors. If the pipeline will be handling hydrogen instead of natural gas, several problems arise with both types of machines due to the difference in properties of hydrogen and natural gas, summarized in Table B.4-l below: TABLE B.4-l: PROPERTIES. OF HYDROGEN AND NATURAL GAS Chemical Specific formula gravity, 0°C, 700 mm H2 Hg 0.08987 CM4 0.7169 Molecular weight 2.016 16.032 Ratio of specific heats 1.41 1.30 These problems will be discussed further in a later section but are briefly mentioned below: a. Both designs will suffer to one degree or another from hydrogen environment embrittlement depending on the materials chosen for the design. b. Reciprocating compressors will have a serious seal- ing problem due to the rapid diffusion of relatively $mall H~ molecules and the attack by H2 on sealing materials in non-lubricated designs. c. Centrifugal compressors will not produce the required pressure ratios without extensive multi-staging; since pressure rise is the product of density and head rise, a lower density gas requires a higher head machine. Furthermore, both machines will have to be built in expanded capacities to deliver the same energy content with hydrogen as they carry with natural gas, since only 26% of the present energy capacity at 750 psi with methane will be delivered when handling hydrogen (Ref.l), due to the lower d~nsity of hydrogen. An example of a reciprocating compressor design now used for a natural gas transmission which might be used to handle hydrogen is shown in Figure B.4-l, taken from Reference 2; examples of a 13-6 -- PAGENO="0863" 857 ROD CROSSHEAD \ SEAL SUCTION VALVE WATER VARIABLE CRANKSHAFT PISTON ROD CYLINDER VALVE PISTON CYLINDER HEAD Figure B.4-1: Reciprocating Compressor for Pipe Line Service (Rexnord, Inc.) PAGENO="0864" 858 centrifugal compressor design presently used to handle natural gas and a multistage design which might be used to handle hydro- gen are shown in Figures B.4-2 and J3.4-3. It is worth noting that in 1972, the installed compressor station horsepower ex- ceeded ten million, (Ref.3). The centrifugal machine has large- ly supplanted the reciprocating machine in natural gas pipeline service for the reasons previously discussed. However, in hand- ling hydrogen, design difficulties arise in generating the re- quired pressure rise (head) with centrifugal machinery and it becomes necessary to go to a multi-stage compressor in order to achieve the head required for a minimum of compressor stations along the pipeline, or to cOnsider another type of compressor, to be discussed in the next section of this appendix. Before leaving this section, however, it is of interest to note that there has never been any hydrogen pipeline system de- veloped to the point where compressor stations have been neces- sary. The most developed hydrogen pipeline system is in Germany and comprises some 130 miles of steel pipe, twelve inches in diameter distributing hydrogen gas generated at 600 psi. The gas simply blows down the pipeline and is delivered to users at 225 psi. Details of this pipeline system can be found in Ref. 4. There has been some hydrogen compressor design and develop- ment experience to date, mostly related to liquification and process work. No such design or development experience appears to exist on the scale required for pipeline application. B.4.l References 1. Wurm, J. and Pastris, R.F., `The Transmission of Gaseous Hydrogen' SPE 4526, 1973. 2. "Selection of Compressing Equipment for Gas Pipelines, Rexord, Inc., Bulletin 226A, Milwaukee, 1954. 3. "Gas Industry Research Plan, 1974-2000', AGA, January 1974, 4. Weil, K.H., "Trip Report on Hydrogen Technology in Germany (1972)", A report to the National Academy of Sciences,Comm. on Motor Vehicle Emissions, Alternate Power Systems. 5. Konopka,A. and Wurm,J., "Transmission of Gaseous Hydrogen" Paper presented at Ninth IECEC,San Francisco,CA,l974. B- 8 PAGENO="0865" I.~. CD w HCD (D~1 P-~ U) P-h t-.P) O(D P30) ~0) P30 ~jP1 P-h 0 ~1 z 03 P1 P3 0 03 0) (1) CD P1 C) CD 0 TWO-STACE CDP COMPRESSOR PAGENO="0866" 860 Figure B.4-3: Centrifugal Compressor for Hydrogen Service B- 10 PAGENO="0867" A 861 B.5 - REGENERATIVE COMPRESSORS A possible solution to the design difficulty discussed in the last section is to utilize the regenerative compressor for hydrogen gas pipelines. "Regenerative" compressors are capable of making the head in a single stage that would normally require seven to eight centrifugal stages. This is because the head coefficient" obtainable from this type of machine is of an order of magnitude higher than that obtainable from a centrifugal machine. However, regenerative machines have been efficiency limited until very recently and have also been generally applied in the low end of the centrifugal compressor specific speed range. Figure B.5-l shows a fairly conventional regenerative turbo~- machine. We see the construction of a multi-blade impeller with open side channel on one side. A barrier in the side channel between the inlet and outlet ports causes the establishment and maintenance of the regenerative flow pattern. As the impeller rotates the fluid circulates in and out of the blade buckets several times during one revolution gaining energy with each re- entry. This type of flow pattern allows the generation of high pressure at low rpm. Assuming a conservative design point head coefficient for a regenerative machine of 3.5, (this design point head coefficient is of the order of five times higher than a comparable design point heat coefficient for a high speed single-stage centrifugal machine), we see in Figure B.5-2 the head which can be made with a regenerative machine at various speeds of rotation for various diameter impellers. The efficiency limitation of regenerative turbomachinery is shown in data presented in Figure B.5-3 giving the comparative efficiency of low specific speed pumps of centrifugal, Barski, regenerative and advanced regenerative designs (Garret) as a function of specific speed. It can be seen that the regenerative * Head coefficient is the ratio of the pressure rise produced by an impeller to the square of the tip speed. When taken at the design point (maximum efficiency) it is usually referred to as the design head coefficient. The. pressure rise produced by a dynamic compressor is a function of the head rise and the density of the gas. B-ll PAGENO="0868" 862 n - j p / ~ i~ ~ Figure B.5-1: Regenerative Turbomachine (Singer) B-12 PAGENO="0869" I.- EL LU I 500 400 300 200 863 100600 1000 2000 4000 6000 10,000 RPM Figure 13.52: Regenerative Turbomachjne Head-Speed-Size Performance 10,000 4,000 3,000 2,000 1,000 13- 13 PAGENO="0870" 0.90 0.80 OJO g 0.60 C-) z ~ 0.50 ~ C.) ~ EL ~ W 0.40 0.30 020 - CENTRIFUGAL GARRET - - - - - - -~ CENTRIFUGAL :INGERSOLL RAND - REGENERATIVE: VARIOUS MFRS BARSKE : SUN DYNE PUMP GARRET :PRIVATE COMM FROMBALJE I I I I 1 L~1 0.10 0 I I 150 250 350 500 700 1000 1500 2000 SPECIFIC SPEED, N5~Jö~N (qpm, rpm, ft.) Figure B.53: Comparative Efficiency of Low Specific Speed Pumps 3000 4000 PAGENO="0871" 865 machine has tended to peak at about 50% efficiency in the low specific speed range, while the centrifugal picks up from this point. Also it can be noted that in very low specific speed ranges the regenerative is more efficient than the centrifugal. Recent developments carried out at Garret Company based on earlier work at Sunstrand Corporation carried out by Dubey under government sponsorship* have shown that it is possible to sub- stantially improve the efficiency of regenerative turbomachinery by the improvement of the ordering of the flow pattern in the side channel, reduction in the extent of impeller blading and better aerodynamic design of the bladed elements. The improve- ment in efficiency obtainable is shown in Figure B.5.3. Figure B.5.-4 shows a diagram of this improved type of regen- erative turbomachine. It now becomes possible to contemplate the use of this design on hydrogen pipeline service, where high horsepower designs are needed. The next section of this report will review the literature and historical development of regenerative turbomachinery and bring us to the point where we can examine the application of the improved regenerative machine for compressing hydrogen gas in pipeline service. B.5.l - Literature Review The regenerative turbomachine appears to have originated in either Germany or Holland shortly after the First World War. It was the subject of a number of Doctoral Theses at German Technical Universities during the period between the wars. Among these are the thesis of Carl Ritter (Ref. 1) at the Technische Hochschule of Dresden, the thesis of Walter Schmeidchen (Ref. 2) also at the Technjsche Hochschule of Dresden, the thesis of Carl Schmidt (Ref.3) at the Technische Hochschule of Hannover and the thesis of Heinrich Engels (Ref.4) at the Technische Hochschule of Hannover. These earlier investigators were con- cerned with exploring over a wide range, the effects of varying * see references, B.5 B-l5 PAGENO="0872" TYPICAL RADIAL SECTION (EXCLUDING PORT AREA) Figure B.5 4: Advance Design Regenerative Turbomachine (Ref. B.5-6) EXHAUST PAGENO="0873" 867 geometry on the design of regenerative machines. The experi- ments involved work varying the proportions of blading to coverage of the side channel over the blading, shape of side channel and blading and the like. As a result of these in- vestigations, a great deal of information was derived allow- ing one to reach the optimum proportions for conventional re- generative turbomachinery design. These efforts have been summarized in a book by Pfleiderer (Ref. 5). Of special interest is the work of Engels dating from 1940 in which, he not only concentrated on the circular radial section for impeller and side channel but also introduced the concept of a guiding ring (which turned out to be the concept used by Silvern (Ref. 6) in his research at Sunstrand)in order to better guide the flow and reduce the chaotic mixing process, thereby raising the efficiency level. However, in Engel's work the ring was attached to a full-bladed impeller and rotated with it, which limited its effectiveness. This point will be further discussed later. Other investigators, following the Second World War, picked up this early work and attempted to develop a rational theory for the type of flow developed within the regenerative machine. One school of thought, the leading exponents of which were Crewdsen (Ref. 7) and Iversen (Ref. 8) postulated the essential flow mechanism as being one of drag induced by the impeller on the stationary fluid in the side channel. Certain explanations of observed performance were obtainable by means of this hypothesis which however, proved to be limited in explaining many of the other features of performance which were observed. Work was also carried out at Massachusetts Institute of Technology (Ref. 9), National Aeronautics and Space Admini- stration (Ref. 10), and Oak Ridge National Laboratory (Ref.ll). The interest at the latter location being one, significantly enough, of utilizing the regenerative machine as a light gas compressor and circulator in the gas-cooled reactor designs which were being developed there. Mention may also be made of the work done by Shimasaka (Ref.l2) and Senoo (Ref.13) where the B- 17 PAGENO="0874" 868 emphasis was on the development of the regenerative turbo- machine as a pump where its low NPSH* performance character- istics are attractive. Recent investigations at Universities have included work by Burton (Ref. 14) and Grabow (Ref.l5) where attempts were made to define and develop further the theory upon which ~a rational design approach to this type of turbomachine could be made. In addition, there were investigations directed toward utilization of this type of turbomachine as a turbine. Emphasis in this area was given in research conducted by Balje (Ref.l6) In the meantime, commercial development of this type of turbo- machine continued, principally as a pump in Germany and else- where in Europe and in the United States as well, where its high head, favorable low NPSH characteristics allowed it to enjoy a special application advantage and where its efficiency limita- tions were not, especially important. This latter factor however, tended to limit the sizes in which this type of machine was built and sold to less than 50 horsepower. This is two orders of magnitude lower than the horsepower requirements of a typical com- pressor station on a natural gas pipeline. In the last 15 years, the machine has begun to be developed as a gas handling device. First, as a high pressure blower (Ref. 17,18) and more rncently moving into the range where com- pressors would normally be applied. Again, this work was pioneered in Germany but has been picked up in the United States and is actively under development at this time in several locations. Among these, may be listed, Garrett Corp. in California; Rotron Manufacturing Co. in Woodstock, N.Y.; and others. This brief review., it is hoped, has served to point the dir- ection in which development of this type of machine is occurring, and to lend support to the concept that it may well be a suitable machine to apply for the purpose of compression of hydrogen gas in pipelines. This point will be discussed in more detail in the next * NPSH, or net positive suction head is a term usually taken to signify the pressure available at the pump inlet above the cavitation pressure at that point. B-l 8 PAGENO="0875" 869 section of this report. B.5.2 - Technical Problems This section and the next will be devoted to a discussion of the technical problems which will have to be faced in apply- ing the regenerative turbomachine for the compression of hydrogen. These fall into groups as follows: (a) the need to raise the efficiency levels of the machine to those levels which are now enjoyed by centrifugal compressors; (b) the need to extend the range of specific speed to higher values than those where the machine has been applied before; (c) the need to eliminate the noise which-the machine will generate at the blade passing frequency at high sound pressure levels, due to the close running clearances between impeller and casing port barrier. Cd) the need to provide adequately for the somewhat peculiar loads that the impeller will throw onto the shaft and bearings as a result of the regenera- tive turbomachine geometry; (e) the need to choose proper alloys or other means to avoid hydrogen enthrittlement. This difficulty is shared with other compressor designs B.5 .3-Possible Solutions, Design Approaches, Recommendations The technical problems which were raised previously may be approached in a number of ways which will now be discussed corresponding to the order in which they were raised in the previous section. (a) It may be possible to raise the efficiency of regenerative machinery beyond the levels which have been obtained thus far by means of improving flow guidance in the side channel through proper proportioning of the turning ring and channel geometry in relation to the blading so that the diffusion process occurs in a more guided manner. Another approach suggested by F. Sisto* would be to utilize the turning ring itself which can be made hollow, as a heat exchanger so that the compression may approach the isothermal condition; that is cir- culate a coolant through the hollow turning ring and reject the heat of compression outside the machine via an auxilliary heat exchanger. * private communication B- 19 PAGENO="0876" 870 (b) The range of specific speed may be extended; that is it may be possible to apply the design to a higher flow rate through improvement in the inlet and outlet porting creating a better match to the blading geometries. As a side benefit, this may also contribute to the raising of eff i- ciency if the inlets and outlets can also be de- signed to provide some turning for the flow. The extent to which this may be achieved is unknown at this time. (c) Noise problems may be approached through two basic means: first, tuned silencers may be provided at the inlet and outlet of the machine designed so that maximum attenuation occurs at the blade pass- ing frequency. These silencers can also be designed so as to provide some attenuation for broad band or aerodynamic noise as well. In addition, it may be possible to reduce the noise level of the machine through staging, that is dividing the total work among two or more impellers although this may in- crease the complexity of the machine to a certain degree. It may also provide a benefit with respect to accommodating the loads developed on the impeller and transferred to the shaft and bearings. (d) The bending and twisting loads that a regenerative impeller develops tend to cause the impeller to rotate in a plane not perpendicular to the shaft. This creates problems in maintaining a uniform clearance between the impeller and the casing port barrier, and also contributes to unbalance and re- duction of bearing life. One way in which it becomes possible to solve this problem is by staging where the impellers are arranged so that the net eccentri- city developed is reduced to zero. It also is possible to design impellers with double-sided blad- ing and to arrange the inlets and outlets in stages in a multi-stage design alternately around the periphery of the casing. One should also try to provide as large a bearing as possible, particularly in overhung designs at the impeller end of the shaft. (e) The problem of embrittlement im a regenerative com- pressor will be in many respects similar to that ex- perienced in other types of compressors with the exception of the following: the impeller itself because of its geometry can be fabricated from cast- ings or forgings essentially in one piece; therefore, stress raisers that may exist in fabricated centri- fugal impellers due to welded construction are eli- minated. B-20 PAGENO="0877" 871 B.5.4 - References 1. Ritter, Carl, "Uber selbstansaugende Kreiselpunipen und versuche an einer neuen Pumpe dieser Art Dissertation, Tech. Hochschule Dresden, 1930. 2. Schmiedchen, Walter, "Untersuch.ungen uber Kreiselpumpen mit seitlichen Ringkanal" Dissertation, Tech. Hochschule Dresden, 1931. 3. Schmidt, Karl A., "Uber luftansaugende kreiselpumpen", Dissertation, Tech. Hochschula Hannover, 1931. 4. Engels, Heinrich, `Untersuchungen an Ringpumpen (Seitenkanalpumpen) Dissertation, Tech. Hochschule Hannover, 1940. 5. Pfleiderer, Carl, Die Kreiselpumpen fur Flussigkeiten und Gase. Wasserpumpen, Ventilatoren, Turbogeblase, Trubokom- pressoren' 5th Edition, 1961, Springer-Verlag, Berlin, pp. 604-619. 6. Dubey, Michael, "Study of Turbine and Turbopurnp Design Param- eters" Final Report, Vol. III, "Low Specific Speed Turbines Based on Tangential Flow Theory". S/TD No. 1735, Sunstrand Turbo Contract NONR 2292(00) TO NR 094-343, 30 Jan. 60. 7. Crewdson, E., `Water-Ring Self-Priming Pumps'. Proceeding Institution of Mechanical Engineers, Volume 170 n 13, 1956, pp. 407-417. 8. Iverson, H.W., `Performance of the Periphery Pump'. ASNE Paper 53-A-102, published in Transactions of the ASMR January 1955, pp. 19-28. 9. Wilson, W.A.; Santalo, M.A.; Oelrich, J.A., `Theory of the Fluid-Dynamic Mechanism of Regenerative Pumps' Transactions of American Society of Mechanical Enginears, Nov. 1955, Volume 77, Pp. 1303-1316. 10. Weinig, Friederich S., `Analysis of Traction Pumps' Wright Air Development Center, WADC Technical Report 54-554 (AD 67 339) June 1955. 11. Burton, D.W., `Review of Regenerative Compressor Theory'. AEC TID 7631, Rotating Machinery for Gas-Cooled Reactor Appli- cation, 1963 pp. 228-242. Gates, P.S., `performance Characteristics of a Peripheral Compressor'. AEC TID 7690 Rotating Machinery for Gas-Cooled Reactor Application. Meeting Nov. 4-6, 1963; pp.76-101. Gates, P.S., `Peripheral-Compressor Performance on Gases with Molecular Weights of 4 to 400~ American Society of Mechani- cal Engineers paper 64 WA/FE-25, for meeting Nov. 29-Dec. 4, 1964. Namba, I.K., `Development of Regenerative Compressor for Helium Circulation', Oak Ridge National Laboratory ORNL-TM- 218, July 20, 1962. B- 21 PAGENO="0878" 872 12. Sbijnosaka, Minoru, `Research on the Characteristics of Regenerative Pump', Bulletin Japan Society of Mechanical Engineers, v 3 n 10, 1960, PP. 191-199. Shimosaka, Minoru and Yamazaki, Shinzo, `Research on the Characteristics of Regenerative Pump', Bulletin of Japan Society of Mechanical Engineers. V 3 a 10, 1960, pp. 185- 190. 13. Senoo, Yasutoshi, `Theoretical Research on Friction Pump', Reports of Research Institute for Fluid Engineering, Kyushu University, Volume 5, n 1, 1948, pp. 23-38. Senoo, Yasutoshi, `Researches on the Peripheral Pump', Report of Research Institute for Applied Mechanics, Kyushu University. Volume III n 10, July1954, pp.53-1l3. Senoo, Yasutoshi, `Influence of the Suction Nozzle on the Characteristics of a Peripheral Pump and an Effective Method of their Removal', reports of Research Institute for Applied Mechanics, Kyushu University. Volume III n 11, 1954, pp. 129-142. Senoo, Yasutoshi, `A Comparison of Regenerative-Pump Theories Supported by New Performance Data', Trans ASME V 78 pp. 1091-1102, July 1956. (Paper 55--SA-44) 14. Burton, J . D., "The Prediction and Improvement of Regenerative Turbo-Machine Performance", Thesis, Southhampton University 1966. 15. Grabow, G., "Investigation on Peripheral Pumps", Second Conference on Flow Machines, Budapest, Oct. 1966, pp.l47-l66. 16. Balje, O.E., "Drag Turbine Performance", ASME paper No. 56- AV-6, March 1956. 17. Hollenberg, J.W., "Vortex Blower Development", The Singer Company, Corporate Research Report No. CR-146, July 1967 (Proprietary). 18. Hollenberg, J.W., "Vortex Flow Study", The Singer Company, Corporate Research Report No. CR-97, 1966 (Proprietary). B- 22 PAGENO="0879" 873 B. 6 -. $tJMEAR? If hydrogen comes into widespread use as a synthetic fuel, large scale pipeline transmission of gaseous hydrogen across the United States will be necessary. Compressor stations along these pipelines will be required to periodi- cally boost the pressure as is now the practice in the natural gas industry. Existing compressor station designs can be adapted for hydrogen service, but at an increase in complexity and overall operating costs tDgether with a loss of simplicity and reliability. Utilization of regenerative turbomachinery as a hydrogen pipeline compressor offers a way to maintain the advantage, experienced by the centrifugal compressor in natural gas pipeline service, as reviewed previously. The regenerative compressor can also be used as a natural gas pipeline compressor; in fact, it can be designed to handle both natural gas or hydrogen or any mixture of the two. Further, it may be possible to accomplish this in a single design which can be adjusted ~ handle a varying mixture by speed control or other means. In either case, the regenerative compressor will have, to be a new design; taking advantage of the latest technology. Technical problems will exist in applying the regener- ative turbomachine in this area but the historical trend in the development of this machine suggests that these technical problems can be resolved and that the regenerative compressor may take its place in hydrogen pipeline service maintaining the advantage obtained from present day centrifugal compressors on natural gas service. B- 23 PAGENO="0880" 874 APPENDIX C - HYDROGEN-FUELED ENGINES ABSTRACT The use of hydrogen (H2) as a fuel for spark-ignition, reciprocating engines was investigated as part of a continuing program. Engine performance parameters (e.g., specific fuel consumption,power output, mean effective pressure, etc.) are related to fuel properties (e.g., chemical energy, molecular weight, etc.) analytically via a series of equations that in- volve the indicated thermal efficiency. Based on fuel-air- cycle approximations, values of indicated thermal efficiency (and the concentration of the oxides of nitrogen generated) are obtained and the performance parameters are evaluated for H2-fueled and gasoline-fueledengine operation; illustrative calculations are presented. Operating experience with 112/air and other hydrogen-fueled reciprocating engines is reviewed with emphasis on thermody- namic performance and pollutant emissions. Experimental data are evaluated in light of the performance-parameter analysis. Performance is seen to suffer from decreasea full-load output unless appropriate fuel injection or supercharging is used; efficiency and pollutant-emission gains are attractive at part- load operation via quality (i.e., mixture-ratio) control. Further analytical and experimental data are required, however, for a comprehensive evaluation of potential, particularly as regards fuel-inj action. C-i PAGENO="0881" 875 APPENDIX C - HYDROGEN-FUELED ENGINES Page C.l - GENERAL INTRODUCTION C-i C.l.i - Scope of Appendix C C-i C.i.2 - On Relating Fuel Properties to Engine Performance C-2 C.2 - FUNDAMENTAL CONSIDERATIONS C-4 C.2.l - Engine Thermodynamic Parameters C-5 C.2.l.l - Thermal Efficiency C-5 C.2.i.2 - Specific Fuel Consumption C-6 C.2.l.3 - Power Output, Work Output and Mean C6 Effective Pressure C.2.l.4 - Techniques for Controlling Engihe Power Output C-7 C.2.l.5 - Positive-Displacement-Engine Air Capacity and C-9 Volumetric Efficiency' C.2.2 - Illustrative Calculations C-12 C.2.2.l - Assumptions Cl3 C.2.2.2 - Results C-l4 C.2.3 - Calculation of Indicated Efficiencies C-16 C.2.3.l - The Air-Standard-Cycle Approximation C-17 C.2.3.2 - The Fuel/Air-Cycle Approximation C-l7 C.2.4 - Air Pollution Considerations C-l8 C.2.4.l - NOx Calculations Based on the Fuel/Air-Cycle C-l8 Approximation C.2.4.2 - Reduction of NOx by Operation at Low ~ C-19 C.2.4.3 - Calculations of NO~ Emissions from Engines C-20 C.2.5 - References c-ai C.3 -RECIPROCATING ENGINES: SUMMARY & EVALUATION OF C-23 OPERATING EXPERIENCE C.3.l - Introduction C.3.2 - Hydrogen/Air Engines C'24 C.3.2.l - Background C-24 C.3.2.2 - Spark-Ignition Engines - Overall C25 C.3.2.3 - "Unmodified", Naturally-Aspirated, Spark- Ignition Engines C32 C.3.2.4 - "Modified", Naturally-Aspirated, Spark-Ignition C49 Engines C.3.2.5 - Supercharged Spark-Ignition Engines C50 C.3.2.6 - Rotary-Combustion Spark-Ignition Engines C-55 C-u 62-332 0 - 76 - 56 PAGENO="0882" 876 Page C.3.2.7 - Compression Ignition Engines C-56 C.3.3 - Hydrogen/Oxygen Engines C57 C.3.4 - Mixed-Fuel Hydrogen Engines C-60 C.3.5 - References C63 C. 4 - SUMMARY C'-68 C.4.l - Fundamental Considerations C68 C.4.2 - Operating Experience C-68 C.4.2.1 - H2/Air Engines (Non-CFI) C-69 C.4.2.2 - H2/Air Engines (CFI, Supercharged) C70 C.4.2.3 - H2/02 Engines C70 C.4.2.4 - Mixed-Fuel Engines C-~7l C.4.2.5 - Compression-Ignition Engines C-72 C.4.3 - Conclusions & Future Plans C7a C-ij~ PAGENO="0883" 877 APPENDIX C - HYDROGEN-FUELED ENGINES C.l- GENERAL INTRODUCTION It appears'that H2 was first suggested as a fuel for an engine by the Rev. N. Cecil in 1820 (Ref. 1). Commercial operation of trucks fueled by H2 was demonstrated over 50 years ago (Ref. 2). Systematic laboratory investigation of its characteristics in a spark-ignition, reciprocating internal-combustion engine was first reported 50 years ago as well (Ref. 3). Since then it has become a major fuel for liquid propellant rocket spacecraft (Ref. 4) and has been used to power aircraft gas turbine engines (Ref. 5). Its use in subsonic transport planes could materially increase the payload achieved with hydrocarbon fuels or materially increase the range of supersonic transport planes. It has been proposed as the fuel (Ref. 6) that could simultaneously end automotive (Ref.7), aircraft (Ref. 8 ) and other combustion- generated pollution of the environment, as well as become the princi- pal energy transport medium of the future as the earths petroleum resources are depleted (Ref. 9). However, in making a decision on the use of H2 vis-a-vis other possible fuels it is important to have knowledge of their comparable performance, for example, the efficiency with which the chemical energy is converted into mechani- cal work (Refs. 1041). C.l.l - Scope of Appendix C This appendix is largely restricted to ordering and summarizing both fundamental considerations and operating experiences with H2- fueled piston engines, reciprocating and rotary. Rocket engine experience is outside the scope of the present program. Although, some of the fundamental considerations apply to gas turbines as well as piston engines, gas-turbine operating experience with H2 as a fuel has not yet been sufficiently reviewed to warrant inclusion of this type of engine in this document. It is planned that the Second Semi-Annual Technical ~apQrt will extend the depth C-l PAGENO="0884" 878 of treatment of piston engines enU oreaOtli of coverage to other H2- fueled engines, notably gas turbines. In Section C.2, "Fundamental Considerations, basic performance parameters are defined and discussed in the light of the peculiari- ties of H2 as an engine fuel. This section serves to clarify sone of the prospective advantages (e.g., efficiency, `quality control" of power) and disadvantages (specific power, torque) anticipatable in H2 use as a fuel, particularly in piston engines. Section C.2 also includes illustrative calculations aimed at putting hydrogen in perspective by comparing it roughly with gasoline as a piston- engine fuel. Finally, Section C.2 serves as background for the sum- mary and discussion of prior operating experience with~ hydrogen in both air and oxygen-breathing piston engines. Section C.3, "Reciprocating Engines: Summary & Evaluation of Operating Experience", ordars and summarizes the data available from previous and current operations with hydrogen-fueled piston engines. Some tentative conclusions are reached regarding overall performance; some value judgenents must, however, be postponed pend- ing further analysis and experimentation on H2-fueled engines. C.l.2 - On Relating Fuel Properties to Engine Performance ExceptIng rockets, by far the greatest operating experience from H2-fueled engines of any class has come from experiments on positive- displacement engines, positive-displacement engines as a class in- clude reciprocating and rotary-piston engines in which the quantity of working fluid (e.g., combustion products) in the engine is at some point(s) in the engine process completely enclosed by solid boundaries (thereby filling a well-defined,clOsed volume). Of all positive-displacement engines, air-breathing, reciproca- ting, spark-ignition, Otto-cycle engines have been most extensively tested. However, all such engines which have been H2 fueled were of designs developed and in varying degrees optimized (over decades) C-2 PAGENO="0885" 879 for use with gasoline as a fuel. Only minor modifications were made in adapting these engines to H2 operation; they are still "gasoline engines when operated with hydrogen. Such engines cannot be con- sidered to have been transformed into "hydrogen engines", optimized for the use of H2. Thus, operations with H2 as a fuel in a gasoline engine are at a congenital disadvantage vis-a-vis gasoline opera- tion, and comparisons are inherently biased against hydrogen as a fuel. However, there is no simple alternative and therefore, herein as elsewhere, such comparisons are made. In order to explain, predict, or otherwise rationalize engine performance data, it is necessary to relate these data to fuel prop- erties. Fuel properties are introduced explicitly in Section C.2 in relationships between efficiency and other performance parameters such as power output, mean effective pressure or torque, specific fuel consumption, etc. ~plicitly, fuel and combustion-product prop- erties also determine efficiency. The fundamental g~ēplicit performance relationships are developed in Section C.2 in a form which shows the influences of the chemical energy of the fuel, its molecular weight, etc. This clarifies some of the influences on engine performance of hydrogen's unique proper- ties. ~pplicit influences of fuel properties on engine efficiency can be seen in the empirical test data of Section 0.3. A classic basis for doing this is by comparing experimental efficiencies with those from analysis of a model idealized engine operation. The fuel/air- cycle approximation has been commonly used as the model for approxi- mating and comparing with the experimental performance of gasoline Otto-cycle engines. In the case of hydrogen engines, however, a search of the literature has revealed such calculations for only two isolated operating points.. As part of the present effort, a computer program has been written to make additional calculations, hut these have not yet been made. For the present purposes, then, Section C.3 compares experimental efficiency data with the two fuel/air-cycle calculations which are available in the literature and with one ad- ditional result calculated "by hand" as part of the present program. C-3 PAGENO="0886" 880 C.2 - FUNDAMENTAL CONSIDERATIONS The purpose of this section is to show the relationship between fuel properties and engine performance parameters. Analytic expres- sions are used whenever possible. Since piston engines are the main concern of this report, the equations will be so specialized. They can be used as a basis for the evaluation of H2 as a fuel, for comparison of H2 with gasoline or other hydrocarbon fuels, and for rationalization and evaluation of actual engine experience reported on in Section C.3. The difference between work (or power) produced on the piston and that which appears on the shaft is due to mechanical losses. These are not of concern here, so attention will be focused on piston work, i.e., that produced by pressure in the cylinder. Such quanti- ties are designated as indicated quantities, i.e., indicated thermal efficiency, indicated mean effective pressure, etc. and are directly influenced by fuel properties. They are used to report engine performance when the purpose is to relate it to fuel proper- ties, including their combustion processes. However, as discussed in Section C.3, there are examples in the literature where shaft (or "brake') work (or power) is reported without sufficient infor- mation (i.e., friction work or friction power) to correct the shaft quantities to indicated quantities. Thus, they are of very limited utility for the present purpose. The most important engine-performance parameter -- it appears explicitly in the equations for all of the others -- is the efficiency of conversion into work on the piston of the fuel chemical energy. Unfortunately, this quantity, the indicated efficiency, cannot be related analytically to fuel properties. It depends on an integra- tion of the effects of fuel properties' engine design, and opera- ting conditions as well ac the ambient conditions at the inlet to the cylinder. Based on the conventional fuel/air-cycle approximations a computer program for indicated efficiency was written, but it ha~ not yet been run at the time of writing. So in making illustrative calculations of other operating parameters, indicated efficiency values from the literature were used in conjunction with one point calculated "by hand". C-4 PAGENO="0887" 881 $ome consideration is given to the calculations of the oxides of nitrogen generated by the combustion of H2 and gasoline in piston engines. Simple models permit calculation of gross trends, but the reSults from more realistic models have not been reported for Ii~. Never- theless, it is possible to rationalize the published results of en- gine experience on a qualitative basis. C.2.l - Engine Thermodynamic Parameters C.2. 1.1 - Thermal Ef ficienc~ The fraction of chemical energy input ~ that appears as mechanical work output (W) is defined as the thermal efficiency (~). That is, r) _W ( (1) For piston engines, if W represents work on the piston, then `7is the indicated thermal efficiency. The efficiency is an extremely complex function of fuel properties, the engine itself, mixture fuel- to-air ratio fed to the engine, means of fuel introduction, cylinder inlet conditions, operating conditions, etc. Thus, many quantities must be exactly specified before W or obtained from experiment can be rationally analyzed. Further consideration of will be postponed until Section C.2.3. The chemical energy input can be expressed as the product of an intrinsic fuel property, its chemical energy per unit mass (ec) and the mass of fuel introduced (~3) so that Eq. 1 can be rewritten as (2) It is seen immediately that the chemical energy and efficiency have equivalent importance in producing a specific work output. Therefore, both must be examined when comparing fuels. C-5 PAGENO="0888" 882 C.2.l.2 - Specific Fuel Consumption The reciprocal of Eq. 2 (3) is defined as the specific fuel consumption (SFC) and is a performance parameter commonly employed to characterize engine fuel economy. Since power output (6~) is the rate at which work is being done as a result of fuel flowing into the engine at the rate (t4), Eq. 3 can be rewritten as 5FC = = (4) which again shows explicitly the importance of ec and . For piston engines, if W is the work on the piston, thenO~is the indicated power. C.2.l.3 - Power Output, Work Output and Mean Effective Pressure The power output of air-breathing engines is limited by their ability to ingest air for oxidation of the fuel supplied. To reflect this, Eq. ~ is rearranged, and the air flow rate ((i~) is introduced into numerator. and denominator to yield The term (&-~/L~) is the fuel-to-air ratio of the mixture actual- ly introduced into the engine. For every fuel there is a unique value of this ratio that produces, ideally, as combustion products only 520 and N2 when ~2 is burned, and only C02, H20 and N2 when hydrocarbons are burned. It is commonly referred to as the "stoichi- ometrically correct" ratio, (F/A)5t. Dividing or "normalizing with this ratio yields the equivalence ratio (~) which ic an index of fuel content, or strength" or "quality" of the actual mixture introduced into the engine. Equation 5 then can be rewritten as ~ (6) 62-~332 1O~6 PAGENO="0889" 883 In particular, for positive displacement engines, the cyclic nature of their operation makes it convenient to consider (bA as the product of the mass of air that. goes through the cycle,(L)~/cycle), and the number of cycles per unit time that the engine undergoes. The work per cycle, W/cycle, through Eq. 2 can be related to~43~/cycle, as W4/e = (7) And if Eq. 7 is multiplied through by the cycle rate, Eq. 6 is ob- tained. Still another useful performance parameter of positive displace- ment engines is the amount of work done per cycle divided by the engine displacement (D). It is defined as the mean effective pres- sure (MEP), and is proporticnal to the engine torque (indicated). From Eq. 7: M E P 1(Ee~ `7 (8) D D Assuming that there is uniform distribution of charge throughout each element. of each cylinder, MEP is an indication of how hard each element of every cylinder is working, and thus is a very useful en- gine parameter in the study of the influence of fuel properties on engine performance. Note that (in contrast to SFC~. P , W/cycle and MEP depend. ex- plicitl~y on an additional intrinsic fuel property (F/A)5t, and an operating parameter,~, as well as the engines capacity for air ingestion,tZ)~, (W~/cycle) or(t~/cycle ) respectively. D C.2.l.4 - Techniques for Controlling Engine Power Output Inspection of Eq. 6 shows that control of is possible by vari- ation of L.)A or~, since is a function of both of these quantities, among others, and ec and(F/A)5t are intrinsic fuel properties. C-7 PAGENO="0890" 884 Control of 6~ through variation of is referred to as `quantity control. It is used almost universally in carbureted, spark-igni- tion piston engines fueled with hydrocarbons. Generally, a decrease in power is achieved through the closure of a throttle valve to constrict the passage of air from the environment to the cylinder intake valve port. When fueled with gasoline, for example, such engines exhibit a fuel-lean operation limit near = 0.75 (Ref.12). And 17 decreases sharply with increasing ~above1~l.l. This range of ~ variation has' been found to be too small for the quality control of their power. However, when fueled with H2, such engines can be operated. down to~~ 0.15 -- although 17 decreases sharplywith decreasing below ~ 0.25 (Ref.l3) .Thus, carbureted spark-ignition piston en- gines are susceptible to practical quality control when fueled with H2, as recognized more than 50 years ago by Ricardo (Ref.l4). This is a prime example of how substitution of H2 for a hydro- carbon fuel opens new possibilities for the control of a particular type of engine. Notice however, that this possibility is not new ~or other types of engines. Hydrocarbon fuels are currently employed in all operational gas turbine and diesel engines -- and their power output is varied by quality control. By inspection of Eqs. 7 and 8, it is clear that W/cycle or REP could be used equally ~ie1l as a basis for discussion of quantity vs quality control of engine output. Since 17 is a different function of §, then it is of ~A (or WAIcy~~e or(ü),~/cycle ) and since power depends on (7 , engine opera~ tions with these two different kinds of power control are not simply comparable even when the same fuel is used. If a different fuel is used with each kind,the fundamental influence of fuel properties on engine performance becomes even more difficult to discern by comparing the results. C-8 PAGENO="0891" 885 C.2.l.5 - Positive-Displacement-Engine Air Capacity and Volumetric Efficiency Air capacity is defined as the quantity of air an engine in- gests per unit time. It is very important in positive-displacement engines since their power output is limited by their ability to in- gest air in order to oxidize the fuel available. During actual engine operation, air does not fill the entire displacement volume of the cylinders due to the presence of combus- tion product gases remaining from the previous cycle, moisture of the air ingested, and the fuel itself if it is introduced before closure of the inlet valve -- which, in the case of H2, could oc- cupy a significant fraction of the total displacement volume of the engine. The rate at which displacement volume can be filled is equal to the cylinder displacement volume times the number of suction strokes by the engine per unit time. In a four-stroke engine there is one suction stroke per cycle for each cylinder, but the shaft must turn two revolutions to complete a cycle. Thus, for each cy- linder, the number of suction strokes per unit time is equal to half the revolutions per unit time (N). So for a four-stroke engine with a total displacement of D, the rate at which volume is made available to the air is ND/2. Multiplying this by the actual density of air in the cylinder at the time of inlet valve closure, (/~l~ yields the actual engine air capacity, ~A~actual' or N0 - (9) Assuming that the chemical species that occupy the cylinder are all in the gaseous state, are uniformly distributed and obey the Ideal-Gas-Law equation-of-state, then, _____ = ____ C~-9 PAGENO="0892" 886 where: P1 is the pressure of the mixture T1 is the temperature of the mixture ~~/cycle is the number of moles of air ingested per cycle is the total number of moles that occupy D per cycle is the molecular weight of air R is the Universal Gas Constant. Thus = ?ck. ~ 7T 7i::) AT~ (11) A~M/s~~ A~ WA/(~ m where: is the fuel molecular weight is the molecular weight of the residual combustion product per cycle is the mass weight of the residual combustion product per cycle the mass moisture induced with the air per cycle is the molecular weight of water It is clear that T1 is greater than the temperature of the engine inlet, due to heat transfer to the fresh charge from hot engine parts and the effects of mixing with the hot residual conbustion products. Also, P1 is less than the pressure at the inlet due to dissipation associated with the intake process. The ideal air capacity is the engine air capacity under ideal con- ditions. In the ideal, air taken fron the environment would flow into the displacement volume, which contained no remaining combustion products, and reach the same temperature and pressure as that which existed at the inlet. It is sometimes useful to separate out the effect of moisture and fuel dilution of the air from the effects of the induction process and the presence of the combustion product gases remaining from the previous cycle. In such cases and in the present approach, the ideal is defined not as above, but in terms of the fuel-air mixture filling the displacement volume at the temp- erature and pressure at the inletS C-b PAGENO="0893" 887 The `volumetric efficiency" (C) is defined as the ratio of the actual air capacity to the ideal air capacity. This is not the usual sense of the word efficiency, and in fact it is really the ratio of the actual density of air in the displacement volume to the density of the air in the cylinder under ideal conditions. Based on the ideal of induced fuel-air mixture filling the chamber at the pressure ~ and temperature (TL) that exists at the engine inlet, the density of air in the mixture at the inlet condition,~ is ~o ē~rp / (12) /~ * ___ ~L ~r~tii/~ ,~ ~ and, therefore, from Eq. 11 and Eq. 12: e='~ ~ (4-)A/Cyc/e 0 (13) - (/J,cIQaI (%~)~`,~ - ~7~i;d~iaj ~ OS Substitution of the appropriate forms of Eq.l2~ pflci 13 into Eqs. 6,7 and 8 yields ~ ____ (14) ~/~j ~ W4/e (15) M ~ E MW~L~ T-==--~-~] (~)~`7(16) R7 L' ~ C-il PAGENO="0894" 888 It is noted that still another intrinsic fuel property, influences positive-displacement engine performance when the fuel is introduced before closure of the inlet valve. The term in the brackets in which fld~appaars reflects the fact that a portion of 0 is occupied by feel vapors. For FL-fueled piston engines, the performance decrement due to this factor could be significant under certain conditions. For gasoline- fueled piston engines the maximum performance decrement duo to this factor is only about 2%. About 50 years ago, Erren (Ref.15)demonstrated experi- mentally that this ~f-related performance decrement could be eliminated simply by injecting the fuel directly into the cylinder after closure of the inlet valve. This will be re- ferred to as CFI (for cylinder fuel injection after closure of the inlet valve). For CFI operation there is no fuel vapor in D, so the term containing MWF does not appear in Eqs. 14, 15 and 16. In contrast to non-CFI operation (e.g., norma]- carburetor, inlet-manifold fuel introduction, fuel introduction at the inlet valve before valve closure, etc.), CFI operation involves supercharging" the cylinders in that they contain a greater mass of mixture than would be ingasted during non-CFI operation. Further, the engine cycle must be different since some of the mixture is pumped into the cylinder at a pressure greater than and the pump work nust be taken into account in calculation of net work output and cycle efficiency. Thus, the perform- ance of CFI engines and non-CFI engines are not simply cornpar- able. - C.2.2. - Illustrative Calculations In this section the influence of fuel properties on posi- tive-displacement engine performance parameters are shown by means of illustrative calculations. The properties of ~2 and gasoline are used in the calculation of SFC (Eq. 4) and MEP (Eq. 16). C-12 PAGENO="0895" 889 The influence of MWF on the performance of non CFI engines is shown explicitly by Eqs. 14, 15 and 16. The influence of on the performance of CFI engines is felt through the amount of work required to pump the fuel into the cylinder and thus impinges on /7 --so it cannot be shown explicitly. For expediency, the influence of on the performance of CFI engines will be ignored in making the illustrative calcula- tions in this section. To signify that this has been done, the engine will be designated as quasi-CFI'. C.2.2.l - Assumptions It will be assumed that `7 for both quasi-CFI and non CFI engine operation are the same at the same CR and ~ . This means that the influence of pumping work is ignored and that the engine cycles are equivalent. In fact, the only CFI feature accounted for here is the nonappearance of the fI~VF term in Eq. 16. Comparisons of SFC and MEP are made at values of that have been found experimentally to result in maximum power and maximum efficiency. For H2, these occur at(5 1.0 and (~ 0.45, respectively (Ref. 16). And for gasoline they occur at 1.1 and~ = 0.85, respectively (Ref. 12). Values of `7 calculated for CR = 10/1 on the basis of the fuel/air-cycle approximation (see Section C.2.3.2) and displayed in Fig. C.3-3 are used. For H21/7 = 0.44 at = 1.0 and = 0.5 atj= 0.45. For gasoline, `7 = 0.42 at~ = 1.1 and `7= 0.48 at -~ = 0.85. Further, it will be assumed that~ = 1, thatWM = 0 and that both fuels are completely vaporized in the CFI mode of operation. C-l3 PAGENO="0896" The properties of gasoline will be taken to be those of iso-octane, so that the following fuel properties apply. Fuel _____ __ H2 51,600 0.029 1,500 2 0.42 Iso-octane 19,100 0.067 1,280 114 0.017 TABLE C.2-l: Fuel Properties for Hydrogen and iso-Octane(Ref 17) 890 e~ (F/A) at MW ~F/A) at C.2.2.2 - Results Insertion of the appropriate values into Eq. 4 and Eq.lO yields MAXIMUM POWER Engine ~H = 1.0 ~lH = 0.44 Performance 2 2 0.42 MAXIMUM EFF IC IENCY = 0.5 = 0.85 17 = 0.48 iso 150 ~~CFITTiT9iiI~ non-~i~ auasi-CFI SFC ~ _______ ______ .35 -~ SFC. iso __~l.ll~.55 0.65 TABLE C 2.-2: Comparison of H2 and Iso-Octane Performance of Positive-Displacement Engines for quasi-CFI and non CFI Operation (CR~l0/l) * The lower heat of combustion is used here for ec. C-l4 PAGENO="0897" 891 SFC comparisons show that 112 i.s better than iso-octane by a factor of about 2.8 at the point of maximum power output. And when is adjusted for each to give maximum efficiency, 112 is superior to iso-octane by about the same amount. MEP comparisons show the importance of fuel-introduction. technique. At maximum power, if CFI is not used,the loss in air capacity reduces the MEP for 112 operation by about 20% below the MEP obtained with iso-octane. While if CFI is used, the MEP for H2 will be about 11% greater than that obtained with iso-octane. When compared at the respective conditions for maximum the relatively low (5required for 112 operation compared to that for iso-octane (i.e., 0.45 vis-a-vis 0.85) results in a severe drop of the MEP for 112 compared to the MEP for iso-octane. For CFI operation,the MEP is only 65% of that obtained with iso- octane and for non-CFI operation it falls even further, to 55%. Assuming the engines were operating at the same speed, had the same number of cylinders and the same displacement, then the power penalty would be the same as the MEP penalty, as shown by Eq. 14-and Eq. 16. As discussed in Section C.2.l.5,jf the same engine is oper- ated with ~2 and iso-octane at the same value of ~, then the emission of the oxides of nitrogen (NO~) air pollutants should be about the same. However, the emission of this pollutant is so sensitive to ~, that at the maximum efficiency values for both ~uels,the emission of NO~ with 112 falls to somewhere between a hundredth to a thousandth of that with iso-octane. Thus, in order to receive the maximum benefit in fuel economy and the benefit of greatly reduced 110x emission, oper- ation of H2-fueled engines near~= 0.45 is called for. However the accompanying power penalty, relative to iso-octane best- economy operation of the same engine, must be taken. Naturally, this power penalty could be compensated for by increasing engine speed and/or size, or perhaps, by "supercharging" to increase P1, or using cryogenic 112 to reduce T1. However, these specu- lations relate to the system within which the engines will work, and such considerations are beyond the scope of this present c-15 62-332 0 - 76 - 57 PAGENO="0898" 892 document. An exaxn~le of the extent to which quality control (i.e. , var- iation) of H2-engine REP might be used can be calculated by means of Eq. 16. The data in Fig. C.3-3 show that for FL2 at = ~, `7= 0.44and atf:0.457 1/ = 0.5, when placed into Eq.16 yield 0~5l for quasi-CFI engines, and: ____ ___ = o ~i for non-CFI engines. The experimental data of Fig.C.3-2 agree data for 112 as shown in Fig. C.3-2. - c.2.3 - calculation of Indicated Efficie~g~ The indicated efficiency of an engine depends on many fac- tors, including fuel type, Q, state of the mixture at the engine inlet, thermodynamic cycle (i.e., sequence of states of the mixture and its combustion products) , combustion time, heat transfer losses, etc. The totality of factors involved is so large and their interactions so complex that it is impossible to model then exactly in detail as a basis for calculation. Historically, in lieu of an exact model, a succession of simplistic models of increasing realism have been used as a basis for calculation. Naturally, hydrocarbon-air mixtures have been the subject of such modeling and calculations for many years. Only recently have 112 -air mixtures been modeled, and then for only a limited range of variables in the more simplistic models (Ref. 18). One objective of the subject progran is to advance the calcu- lations for H2-air mixtures. Almost all of the H2-fueled positive-displacement engine data acquired to date have been obtained with engines nominally operating on the Otto cycle. This cycle is, therefore, of most interest here. C-l6 PAGENO="0899" 893 C.2..3 .1 - Th~e Air~Standard-Cycle Approximation The air-standard-cycle approximation for engines involves two classes of approximations: One has to do with idealization of the working fluid that goes through the cycle and the other has to do with idealization of the cycle itself. The working fluid, that is, the fuel-air mixture and its combustion products,are assumed to have constant specific heats, and have the same physical constants (e.g., molecular weight) as air. The ideal Otto cycle involves consideration of a fixed working fluid that goes through a succesrion of thermodynamic states from the initial state at T1 and P, (with the piston at bottom dead center) to return the fluid to its initial state. This approximation results in asimple equation relatiap ~? to: (i) engine compression ratio (CR) and (ii) the ratio of the specific heat of the working fluid at constant pressure to its specific heat at constant volume (k), / (~7) In practice, all of the assumptions are violated, and the values of found experimentally fall far short of those pre- dicted by Eq. 17. C.2.3.2 - The Fuel/Air-Cycle Approximation This level of approximation is based on the real properties of the intake mixture and combustion-product gases in the idealized Otto cycle described in C.2.3.l. The level of complexity intro- duced is such that /7 can no longer be explicitly related to CR or any other variable. Numerical computations of can be made, however. The technical literature contains many examples typi- fied by those of Ref. 19 for hydrocarbon-air mixtures. For H2-air mixtures, a search of the literature revealed only one publ.cation reporting the results of calculations of ?for the fuel/air-cycle approximation (Ref. 18). They were made for = 0.365 and~= 0.48 and arepresented graphically in Fig.C.3-3. C-l7 PAGENO="0900" 894 Also plotted is one point at~= 1 calculated by hand during the subject program. They are consistent with the expectation that should decrease as jincreases. An increasing fraction of the chemical energy of the working fluid becomes unavailable for use- ful work because of dissociation of the combustion products and because of increases in the specific heats of these products. And eventually, for ~7l, `? should fall shmbply with further increase of due to expulsion of unburned fuel in the exhaust (due to lack of oxygen in the mixture). A computer program has been written with the intention of calculating /7 over a broad range of variation of C»=and CR and other performanc2 parameters. The calculatigns had not been com- pleted at the time this document was written. Therefore, funda- mental comparisons of H2 with hydrocarbon fuels on the basis of fuel/air-cycle approximations can be made only on a very limited basis at this time. C.2.4 - Air Pollution Considerations Carbon monoxide, unburned hydrocarbons, and the oxides of nitrogen (NOx) are generated during the operation of hydrocarbon- fueled engines. Hydrogen-fueled engines generate only NOx due to the absence of carbon atoms -- assuming, of course, carbon- containing lubricants do not inadvertently enter the cylinder and burn. Thus, H2 is inherently superior to hydrocarbons in this regard. The remainder of this section will deal with BOx generation and emission associated with H2-fusled engines. C.2.4.l - NOx Calculations Based on the Fuel/Air-Cycle Approximation Within the framework of the fuel/air-cycle approximation (Section C.2.3.2), the NOx concentration at the maximum cycle temperature can be readily calculated as a result of the thermo- dynamic and chemical equilibrium that is assumed to exist in the combustion products. Such calculations have been performed by others (Ref. 20) over a rather limited range of variation (i.e., between 0.8 and 1.2) for standard conditions at the inlet of an engine opera- ting at CR = 9. Apparently, these are the only results of BOx C-l8 PAGENO="0901" 895 calculations ~or I-12--fueled, Otto-cXcie engines that appear in the open literature.. They are di.spla~ed in Fig. C.3-~5~ and along with the results for gasoline,are also shown in Figure C.3-7. These calculations indicate that both fuels will result in about the same concentration of NO~ at the same value of with H2 combustion generating slightly greater concentra~ti~ons. An indication of the calculated dependence of NO~ concen- tration on when ~is decreased below 0.8 can be found in Ref. 21. These calculations were carried out for jet propulsion fuel and H2 burned at constant pressure of 5 atmospheres, in a gas-turbine combustor that has a mixture inlet temperature of 800°K. Therefore, they cannot be compared quantitatively with the calculated results of Ref.20, but they do have several use- ful aspects; First, they show that as is reduced below 0.8 or so the NO~ concentration reaches a maximum and then falls again; Second, comparative values f or aviation fuels are presented; Third, and perhaps most importantly, a separate set of calcula- tions have been made by the authors which account for the rate of generation of NO~ in the combustion products, i.e., the con- centration of in the combustion products is calculated at a time of two milliseconds after burning (as well as at equilibrium) --and this chemical kinetic calculation is an extension beyond usual fuel/air-cycle approximation calculations. All of the calculated results that appear in Ref.20 and Ref. 21 show that H2 is expected to generate a bit more than practical hydrocarbon fuels at the same value of ~. So, on this basis, H2 is .slight].y. inferior to hydrocarbon engine fuels. C.2.4.2 - Reduction of No by Operation atLowé It has been found that naturally-.aspirated,reciprocating engines, when H2-fueled exhibit a much lower lean limit of operation (lower ~) than when they are operated with hydrocarbons (Section C.3). And it is this ability to operate at low ~(say, ~~0.5) that yields for H2 the benefit of low NOx production. However, as shown in Section C.2.2.2, for H2-fueled positive_displacement engines,the NEP at~= 0.45 compared to that at~=l.0 is calculated to be lower by .5l96fOrquasi-CFI operation and 0.61 for non CFI operation. So a power penalty cannot be avoidedat low C-l9 PAGENO="0902" 896 C.2.4.3 - Calculations of Emissions from Engines The fuel(air-cycle approximations are sufficiently removed from the reality of actual engine operation that calculations of BOx concentration based upon it are not expected to correspond to NO~ concentrations found in the exhaust of operating engines. The authors of Ref. 22 have constructed a model that accounts for NOR_concentration non-uniformities throughout the cylinder re- sulting from combustion initiation before piston top-dead-center, heat losses to the walls and finite rate of combustion wave travel. These influences can be coupled ~ith a ~kinetic model for the finite rate of formation of NOx in the combustion-product gases as well as finite rate of decomposition in the combustion pro- ducts as they are cooled by expansion during the power stroke This permits calculation of the NO concentration in the exhaust gases leaving the engine. Only the results with hydrocarbon fuels have beenģ published, though reportedly (Ref. 28) ,calculations are in process fo~ the case of H2-fueled engines. Comparison of experimental results arith BOx emissions calculat~ed h this more complex model permits rationalization of the influence of engine operating conditions other than ~ and inlet conditions, e.g., engine speed and degree of spark-advance. For ecample, retarding the degree of spark advance generally results in a de- crease in NOx emissions. The faster burning velocity of H2-air mixtures relative to gasoline-air mixtures frequently leads to H2-fueled engines being operated with a degree of spark advance that is relatively retarded compared to hydrocarbon-fueled engines. Based on this consideration, the NO~ emissions from H2- fueled engines would be expected to be lower than that from hydrocarbon fueled engines. However, other factors are important as well. Until these more complex models are reality-tested, and more calculations are performed for the case of H2-fueled operation, more detailed comparison of NOx emissions arc not warranted. However, quantitatively, at the same value of ~ the slightly larger concentrations of NOx generated by 112-fueled operation (Fig. ) will tend to be reduced by spark-retardation, etc. Sc that the NO~ actually emitted in the engine exhaust be about about the same for H2 and gasoline operation. C-20 PAGENO="0903" 897 C.2.5 - References 1. Billings, R.E. and Lynch, F.E., `History of Hydrogen-Fueled Internal Combustion Engines, Publication No. 73001, Billings Energy Research Corp., Provo, Utah, 1973. 2. Erren, R.A. and Campbell, W.H., "Hydrogen: A Commercial Fuel for Internal Combustion Engines and Other Purposes", J. Inst. of Fuel (London) Vol. 6, No. 29, June 1933, pp. 277-290. 3. Ricardo, Jr.R. "Empire Motor Fuels Committee Report', Proceed- ~a~L Inst. of Auto. Eng., Vol 18, 1923, pp. 327-341. 4. Scott, R.B., Denton, W.H. and Nicholls, ~ and Uses 2L~4~uid Hydrogen, The Macmillan Co., N.Y.C., N.Y. ,l964, pp 149-180. 5. Proceedings of NASA Working Symposium on Liquid-Hydrogen- Fueled Aircraft, Held at NASA Langley Research Center, Hampton, Va., May 15-16, 1973. 6. Wail, K.H., "The Hydrogen I.C. Engine Its Origins and Future in the Emerging Energy-Transportation-Environment System", Proc., 7th Intersociety Energy Conservation Engineering Conference, San Diego, Calif., Sept.1973, pp. 1355-1362. 7. Gillis, J.C., Pangborn, J.B. and Fore J.6, "Synthetic Fuels for Automotive Transportation", Paper presented at the Spring Meeting of The Combustion Institute, Madison, Wisconsin, March 26, 1974. 8. Austin, A.L. and Sawyer, R.F., "The Hydrogen Fuel Economy and Aircraft Propulsion", AIAA Paper No. 73-1319, Presented at the AIAA/SAE 9th Propulsion Conference, Las Vegas, Nevada, Nov. 5-7,1973. 9. Gregory, D.P., ~ System, American Gas Associ- iation Report, Catalog No. L2ll73, August, 1972. 10. Johnson, J.E. "Economic Perspective on Hydrogen Fuel", Presented at The Hydrogen Economy Energy (THEME) Conference, Miami Beach, Fla., March 18-20, 1974. 11. Sevian, W.A., Salzano, F.J., and Hoffman, K.C., "Analysis of Hydrogen Energy Systems", Brookhaven National Laboratory Report BNL 50393, Feb. 1973. 12. Ragowski, A.R., "Elements of Internal-Combustion Engines" McGraw-Hill Book Company, Inc., N.Y.C., N.Y. ,l953. 13. Breshears, R., Cotrill, H., and Rupe, J., "Hydrogen Injection for Internal Combustion Engines", presented at EPA Alternate Automotive Power Systems Coordination Meeting, Ann Arbor, Mich., May l974~ 19 pp. C-21 PAGENO="0904" 898 14. Ricardo, H.R., `Empire Motor Fuels Committee Report", Proce~~fl~s, Inst. of Auto.Eng., Va 1. 18, 1923, pp. 327-341. 15. Erren, R.A. and Campbell, W.H., "Hydrogen: A Commercial Fuel for Internal Combustion Engines and Other Purposes, J. Inst. of Fuel (London), Vol. 6, No. 29, June 1933, pp. 277-290 16. King, R;O. and Rand, H., "The Oxidation, Decomposition, Ignition and Detonation of Fuel Vapors and Gases, Pt. V. The Hydrogen Engine and the Nuclear Theory of Ignition", Can. J. of Research 17. Taylor, C.F. and Taylor, E.S., The Internal Combustion Engine (2nd Ed.) International `i~tbook Co., Scranton, Pa., 1961, pp. 66-71. 18. King, R.O., Hayes, S.V., Allan, A.B~, Anderson, R.W.P., and Walker, E.J., "The Hydrogen Engine: Combustion Knock and the Related Flame Velocity", Trans., Engineers Inst. of Canada, Vol. 2, No. 4, Dec. 1958, pp.143-148. 19. Taylor, C.F. and Taylor, E.S., The_Internal Combustion Engine (2nd Ed.) international Textbook Co., Scranton, Pa., 1961, pp. 66-71 20. Starkman, E.S., Sawyer, R.F., Carr, R., Johnson, G. Huzio, L., AtlernatiVe Fuels f or Control of Engine Emission', J. Air Poll. Contr.Assoc., Vol 20, No. 2, Feb. 1970, pp 87-92. 21. Grobman, 3., Norgren, C. and Anderson, D. "Turbojet Emissions, Hydrogen versus JP, "NASA TM X-68258, May 1973. 22~ Heywood, J.B., Mathews, S.M., and Owen, B., "Predictions of Nitric Oxide Concentrations in a Spark-Ignition Engine Compared with Exhaust Measurements", SAE Paper No. 710011, 1971, 12 pp. 23. McLean, W.D.(Cornell Univ.), Personal Communication, March 26, 1974. C-2 2 PAGENO="0905" 899 C.3 - RECIPROCATING ENGINES: SUMMARY & EVALUATION OF OPERATING EXPERIENCE C.3. 1 -Introduction The widespread current use of reciprocating engines, both mobile and stationary, warrants attention as a potential appli- cation for hydrogen fuel. The "recip" has been developed ex- tensively into a low cost, reliable powerplant, competitive in power and efficiency with other hydrocarbon-fueled engines. While not nearly so developed as its gasoline-fueled counter- part, the hydrogen-fueled recip has already shown enough promise so as to be the most-investigated of hydrogen-fueled powerplants. Owing to its similar thermodynamics and application, the rotary combustion' (Wankel) engine is treated in this section along with other types of true reciprocating engines. Each of these categorie~ has been investigated experimentally, but most attention has been given to the hydrogen/air, spark-ignition engine. Operating experiences with hydrogen-fueled reciprocating engines can be readily categorized by way of the reactants used: Ci) hydrogen/air (ii) hydrogen ± other fuel/air (iii) hydrogen/oxygen or by way of engine type: Ci) spark ignition (ii) compression ignition or by way of induction method: (i) naturally-aspirated (ii) supercharged Reciprocating heat engines (e.g., Stirling and Feher-cycle engines) which do not use hydrogen combustion products as a work- ing fluid are not dealt with in this section. C- 23 PAGENO="0906" 900 C.3.2 - Hydrogen/Air Engines C.3.2.1 - Background As mentioned above, the spark-ignition hydrogen/air engine has been most widely investigated, in fact, since the 1920's. Compression-ignition hydrogen engines were used in the 1920's and 1930's but no operating experience appears to have been re- ported since World War II. Until about 1970, published data on hydrogen operation of reciprocating engines has been almost exclusively from ~ingle- cylinder, naturally-aspirated,(RonCFI) ,test-bed engines. While some early multi-cylinder operating experience is recognized, quanti- tative data and operational details are very incomplete. Simi- larly, reports of fuel-injection at either low or high pressure has been very limited. Expectedly, it did not prove difficult for engines designed primarily for gasoline to be operated on hydrogen, as anticipated even by an early science-fiction writer (see Ref. 1). No major accidents have occurred during such op- erations, though a few engine failures attributable to hydrogen use have been reported e.g., (Ref. 2). The major operational problem exposed to date is that of performance. As is shown below, all available quantitative test data indicate, for example, a substantial decrease in peak power available from a naturally aspirated spark-ignition engine op- erated with hydrogen rather than gasoline. This is consistent with the fundamental considerations and illustrative calculations of Section C.2, above. In contrast, however, spark-ignition super- charged (including CFI) engines add compression-ignition engines have not been investigated enough to allow such statements. The summaries following draw performance information from such operational data as are available, Performance variables such as: Ci) power output (ii) specific power output (power/displacement, power/piston area) (iii) mean effective pressure C-24 PAGENO="0907" 901 (iv) thermal efficiency (v) exhaust emissions are emphasized in relation to operating variables such as: (i) compression ratio (ii) equivalence ratio (fuel/air mass ratio relative to stoichiometrically correct) (iii) speed (of rotation and of piston displacement) As is seen below, a comprehensive view of prior experi- mental data of this type allows a useful quantitative char- acterization of hydrogen-fuel operations, at least for the naturally-aspirated spark-ignition engine. C.3.2.2 - Spark-Ignition Engines - Overall The historical trend of experience with hydrogen-fueled spark-ignition engines is apparent in Tables C.3-l and C.3-2. These tables of engine specifications suniniarize prior conditions for operating both unmodified "Otto-cycle" engines and those recent engines which have been "modified" to provide f or exhaust- gas recirculation ("EGR") and water-injection ("WI"). "Quality control" (fuel/air ratio variation), rather than "quantity con- trol" (throttling), has been used with rare exception. It is noteworthy that virtually all these engines have been used for relatively modest test programs using hydrogen as a fuel. Often very specific reasons for testing limit the data obtained, e.g., the knock-limit tests of Downs at al. (Ref. 3) or Anzilotti et el. (Ref. 4,5). In other cases, testing was for demonstration pur- poses, e.g., for the 1972 Urban vehicle Design Contest (Ref's. 6, 7). More recently, specific concerns for part-load efficiency (Ref. 8) and pollutant emissions (Ref. 9,10) have yielded data that are interesting new explorations. However, again, these are compromised in utility owing to the limited test aims, programs, (and presumably funding) involved. Several current investigations are reportedly of somewhat more comprehensive scope (Ref's. 11,12), but data have not yet been reported from these. Typical of pre- sently-available data is a lack of indicated (rather than the less- useful brake) horsepower data at commonly high piston speeds over C-25 PAGENO="0908" TABLE C.3-1: SUMMARY OF HYDROGEN/AIR ENGINE EXPERIENCE - ENGINE SPECIFICATIONS 8 POWER OUTPUT INVESTIGATOR NO. OF CYLINDERS DISPLACE- MENT (IN3) COMPRESSION RATIO , MAX. ENGINE SPEED (RPM) - MAX. PISTON SPEED (FT/MIN) - MAX. REPORTED POWER (HP) MAX. POWER DISPLACEMENT (HP/IN3) MAX. POWER PISTON AREA (HP/IN2) Tizard (Ref. 48) 1 127 - - , - - Ricardo 1 127 5.45/1 1500 2000 28 * .22 1.76 (Ref. 20) " 7/1 `~ 36 .28 2.26 (Ref. 29) 1 127 5.45/1 1500 2000 - - - Burstall (Ref. 21) 1 127 5/1 7/1 1000 1333 15.5 18.7 .12 .18 0.97 1.18 Erren (Ref. 1) - - 8/1 - - ~ - - - Egerton (Ref. 47) - - ~ - - - - - - Oemichen (Ref. 27) - - 12/1 1500 - - - . - King (Refs. 2,16, 22,23) 1 37 4/1-20/1 1800 1350 12 .32 1.44 Downs (Ref. 3) 1 31 8/1-20/1 1500 - ~ - - - (Refs. 4,5) -- 1 8/1-12/1 ~ 900 - - C- 26 PAGENO="0909" C (CONT'D.) INVESTIGATOR NO. OF CYLINDERS DISPLACE- MENT (IN3) COMPRESSION RATIO MAX. MAX. ENGINE PISTON SPEED SPEED (RPM) (FT/WIN) MAX. MAX. POWER REPORTED DISPLACEMENT POWER (HP) (HP/IN3) MAX. POWER PSTON~~K HP/IN2) .51 Holvenstot (Ref. 15) 8 3850 8/1 550 825 217 .056 Kane (Ref. 25) (Ref. 26) 1 1 37 37 6/1-16/1 14/1-20/1 900 900 675 675 - - - - - - Swain (Ref. 13) 4 98 9/1 2600 1200 16(1) .16(1) Billings (Ref. 9) 1 6.65 5.5/1 2900 725 1.64 .25 .370 Adt (Ref. 45) 4 197 10/1 1400 875 6.9(1) .035(1) .13(1) Finegold (Ref.6) 8 351 8.9/1 - - - - Lynch (Ref. 24) -~ Various, f ew details g - iven ~-~---.-~.- ~ -~ Adt (Ref. 46) 8 197 10/1 ~ 1450 906 16.8(1) 33(1) Breshears (Ref. 43) 8 - 350 L - . 2000 8.5/1. 1500 - 870. 43 .12(1) *43(l) Finegold (Ref.8) 8 Stebar (Ref. 10) 1 37 8/1 1200 900 1.3 . .035 . .16 C-~27 PAGENO="0910" TABLE C.3-1 (CaNTO.) MAX. MAX. PISTON MAX. REPORTED MAX. POWER DISPLACEMENT MAX. POWER PiSTON AREA INVESTIGATOR Thomas NO. OF CYLINDERS 4 DISPLACE- MENT (IN3) 140 COMPRESSION RATIO 8/1 SPEED (RPM) 2500 SPEED (FT/HIM) 1500 POWER (lIP) i2.~ (HP/IN3) .086(1) (HP/IN2) .31(1) (Ref. 28) NOTES: (IT based on brake rather than indicated horsepower C-28 PAGENO="0911" INVESTIGATOR . {__________ AT MAX. REPORTED POWER_________ AT MAX. REPORTED EFF IC. PERFORM- ANCE CURVES? EQUIV. RATIO, ~ THERMAL EFFIC., ~ MEP I (PSI) EXHAUST NO (PPM) EQUIV. RATIO, ~ THERMAL EFFIC., (%) MEP * (PSI) EXHAUST NO (PPM) Tizard (Ref. 48) - - - - - - - - - Ricardo (Ref. 20) ~ (Ref. 29) sl.>1.O - ~~(4) 31 43(3) 33(4) 115 74(3) - - ~ .38 - ~ 38 - 4O~'~ 60 - - - - - Yes No No Burstall (Ref. 21) .77 .85 31 37 94 118 - .38 .50 35 38 53 77 - Yes Erren (Ref. 1) - 45 - "none observed" - 45 - "none observed" No Oemichen (Ref. 27) - - - I - - 52 - - No King (Refs. 2,16, 22,23) 1.0 38 (CR = 14/1) 143 - .39 52 (CR = 20/1) 60 - Yes Downs (Ref. 3) - - - - - - - - No Anzilloti (Refs. 4,5) - - . - ~ - - ~ - - - No TABLE C.3-2: SUMMARY OF HYDROGEN ENGINE EXPERIENCE - PARTIAL PERFORMANCE DATA cc C-29 PAGENO="0912" PAGENO="0913" TABLE C.3-2 (CONT'D.) 0 INVESTIGATOR AT MAX. REPORTED ~OWER_________ AT MAX. REPORTED EFFIC. * PERFORM- ANCE CURVES? EQUIV. THERMAL RATIO, ~ EFFIC., (%) - 23(l)(2) 1 MEP (PSI) EXHAUST x NO (PPM) EQUIV. I THERMAL I RATIO, ~ EFFIC., n -- I (%) - I - MEP (PSI) EXHAUST x NO (PPM) Thomas (Ref. 28) 27(~2) - - No NOTES: ~1T based on brake rather than indicated horsepower (2) not at aaxiaum power; only one operating point reported (3) limited by preignition and/or backfire (4) varying heat rejection reported at varying % full load C-31 PAGENO="0914" 908 a range of speeds and fuel/air ratios. Reported performance is summarized in Table C.3-l and C.3-2 for `unmodified and"modified' engines. Cases for which performance curves of any type are available are identified. However, it was judged sufficient in summarizing briefly to. char- acterize just two key operating points, whenever possible: (i) "maximum" power output ~max~ (ii) "maximum" thermal efficiency ("n~ax") In each case, the term `maximum" implies simply the conditions of the largest reported value for either performance variable; the values are not necessarily the maxima which might have been observed using a different or more complete test plan, etc. C.3.2.3 - "Unmodified" Naturally-Aspirated Spark-Ignition Engines In this section only those engine operations are considered which involve the admission of hydrogen and air together into the engine cylinder. "Port injection" (Ref.l3) is counted in this class. Direct injection of fuel into the engine cylinder(CFI) is considered below under the separate heading of "supercharged" engines; the effects of such hydrogen injection hinder direct comparison between operation with natural aspiration and with injection.* Data from operations involving EGR and WI are con- sidered in the next section. Collected thermodynamic performance data are shown in Figs. C.3.l and C.3-2 where thermal efficiencies (~j) and mean effec- tive pressures (MEP) are plotted as functions of equivalence ratio (c5). The points shown represent values calculated from experimental data in a way which allows rough comparison despite * While not explicitly recognized in Ref.l4, direct injection of gaseous hydrogen into the (closed) cylinder in effect yields variable supercharging as equivalence ratio is varied. Though not highly significant in the case of high-molecular- weight hydrocarbon fuels, this effect is substantial with (low-molecular weight) hydrogen. - C-3 2 PAGENO="0915" 0.E30 ~:- 040 0 z Li 0 Li- Li~ Li -i Li 0.20 909 EQUIVI~LENCE RATIO, c~) FIGURE C.3-1: Collected Experimental Thermal Efficiencies of 112/Air, Non-CFI Engines (Data scaled to common CR = 10/1) 0 0.5 1.0 C-3 3 PAGENO="0916" 910 200 (I) 0~ w D U) Cl) w 3- ui 100 > I- C-) w w z w 0 0.5 EQUIVALENCE RATI0,~ FIGURE C.3-2: Collected Experimental Mean Effective Pressures of Ha/Air, Non-CFI F.naines (Data scaled to common CR = 10/1) 0 I.0 C-34 PAGENO="0917" 911 the differences in compression ratios at which the experimental data were obtained. The method used was that of scaling each reported efficiency to the corresponding efficiency at a common, reference CR (10/1) via: (~`\~a ~ of~ ~ro ca~ of~ ~1T~~ST c~e. / ~ s~ro)var~r C~ REP data were similarly scaled, though the process is less justi- fiable in this case; there are CR influences on REP from sources beyond those that influence efficiency (volumetric efficiency effects). One such is intake(manifold) pressure. Most of the hydrogen-engine data reported are Opparently for wide-open jthrottle (ROT) operation. However, in two cases (Ref's 9,15), there is concrete evidence that manifold pressures were substanti- ally below atmosphere. In one casa (Ref. 9), the sub-atmospheric manifold pressure is cited, and the REP data from this reference were corrected to standard-pressure intake conditions to allow direct comparison with other ROT data. The other data which could not be corrected in this manner are not included in Fig's. C.3-l and C.3-2. Experimental data for hydrogen injection directly into the cylinder (CFI) are not included (Ref.14). In a few cases, only ~-vs-c~ data were available experi- mentally. These efficiency data might have been extended into MEP-vs-~ data using Eq. 16 and the assumption that volumetric efficiency is l00%.* However such REP data are not strictly com- parable with directly measured REP values; the latter can be ex- pected to be lower owing to actual volumetric efficiencies less than 100%. Therefore, only directly measured REP's are displayed in Fig. C.3-2; none calculated from efficiencies have been in- cluded. Shown for reference in Figs. C.3-l and C.3-2 are several cal- culated values from fuel/air-cycle analysis of the hydrogen/air engine: indicated efficiencies are shown for ~ = 0.365 and 0.48 * i.e., that there is no net effect of residual product gas and of density change of the intake mixture durin9 induction. C-35 - PAGENO="0918" 912 (Ref. 16) and for ~ = 1.0 (preliminary calculation from the present program). In one case (~)= 1.0), a corresponding dir- ectly calculated NEP value is available; however, in the others directly calculated MEP data are not available. Therefore, to produce three comparable fuel/air-cycle values for MET to dis- play in Fig. C.3-2, efficiency data were used to calculate all fuel/air cycle NET values indirectly as described immediately above by assuming volumetric efficiency (a) to be 100%. Considering the wide variety of engines (and compression ratios) from which the data were obtained, some data scatter is to be expected but rough trends are clearly evident. The trends indicated by the experimental data are reasonable in comparison with the calculated values. The experimental efficiencies are 80 to 90% of the calcu- lated fuel/air cycle efficiencies for hydrogen/air. This 80 to 90% range in volumetric efficiency includes the 80 to 85% range expected in gasoline engines. ~-Iowever, the 90% extreme is high compared with gasoline/air values. It is notable that the highest efficiency values in comparison with fuel/air-cycle values come from the efforts of King (Ref. 16). While King worked carefully and more extensively than other investiqators, there is still no assurance that his values represent the best attain- able; he was, after all, working with engines only slightly modi- fied from their original, gasoline-operation designs. It has been proposed that some losses in the real hydrogen engine (e.g., combustion-time losses) might be lower than with gasoline. The highest of the values assembled here lend some substantiation to this proposal. However, further evaluation of this probability requires currently unavailable experimental data for both gasoline and hydrogen in the same engine (at the same or over the same ~ range) and the comparison of these data with fuel/air-cycle calculations which have not presently been reported. The possibility of doing such a comparison is limited to the - range for which gasoline can be burned ( ~>0.75),and the only current data for both gasoline and hydrogen operation in this range C- 36 PAGENO="0919" 913 (with ~the same engine) are those of Billings (Ref. 9). Un- fortunately, Billings data are not for optimum spark advance (e.g.., max.Brake NEP). Therefore, Billings' data are not usable for judging the relative attainment of fuel/air-cycle performance by gasoline and hydrogen engines. The experimental MEP data of Fig. C. 3-2 are more extensive (and also more scattered) than the hydrogen-engine efficiency data~, The measured ME? values are60 to 80% of those calculated from fuel/air cycle efficiencies. These actual MEP data can be expected to be lower than those shown in Fig. C.3-2 and those calcu- lated from fuel/air-cycle efficiencies for two reasons: (i) Actual c less than calculated (ii) c- 0 z LU 0 LU -J 2 LU = I- 0.6 0.4 0.2 0 ~`, I I I 0 0.5 .0 C-39 PAGENO="0922" 200 C/) 0~ Li a: C/) C/) Li a: a- Li > F- C-) Li U-. Li 2 Li 0 916 0 0.5 1.0 EQUIVALENCE RATI0,c~ FIGURE C.3-4: Calculated ~1ean Effective Pressures of Non-CFI Gasoline/Air and H2/Air Enqines (Calculated from Fuel/Air-Cycle Efficiencies, CR = 10/1) C-40 PAGENO="0923" 917 all the REP values for hydrogen shown in the figure were cal- culated from efficiency values as explained earlier. To provide comparable gasoline-engine data, REP's were calculated by the same method from efficiency data (even though directly calculated REP data are available for gasoline; Ref. 17). The previously cited equivalence of volumetric efficiency in actual gasoline and hydrogen engines justifies this comparison of indirectly cal- culated REP values. Fig. C.3-4 evidences the much discussed output-power penalty incurred by using hydrogen rather than gaso- line; at ~= 1., the REP for hydrogen is approximately 20% below that of gasoline. At a given operating speed, a given engine displays power output proportional to REP (by definition) and, therefore, at ~ = 1 hydrogen-engine power could be expected to be about 20% below that from a gasoline engine. In consideration of Eq. l~5, this 20% loss in power can be seen as deriving from a 5% decrease in efficiency and a 15% decrease in the chemical energy of the input charge to the hydrogen engine at ~ = 1. As %i de- creases, the 15% chemical energy factor dwindles to nothing until, at low ~ , the chemical energy of the inlet charge is theoretically even higher with hydrogen than with gasoline. Fig.C.3-4 shows this. While further comparisons of these incomplete REP data can be made, it is not within the scope of the present report to do so. The significance of these values in a particular application re- quires considerations well beyond those relevant to the present summary and evaluation of operating experience. Such consideration will be more appropriate at a later point in the present program and will be given at that time. Exhaust emissions from hydrogen-fueled engines have only re- cently been measured and reported as indicated by the total oxides- of- nitrogen ("NO~") data of Table C.3-2. Table C.3-3 summarizes the reports of emissions other than NOR. Figure C.3-5 shows the NO~ data from "unmodified" engines (no EGR or WI) for which corresponding equivalence ratios are reported. In two cases (Ref's 9,10), NQ~ emissions from a given test engine are reported for both gasoline and hydrogen operation. Also shown C-4l PAGENO="0924" 918 TABLE C.3-3: Maximum Reported Emissions of CO and Unburned Hydrocarbons from Non-CFI, H2/Air Engines (Attributable to Lube Oil Ingestion) INVESTIGATOR CO (gm/ihp-hr) MC (gm/ihp-hr) CONDITIONS Finegold (Ref. 6) 0m o~ 1973 CVS test cycle Breshears (Ref.43) <<.1 ~ < 1 0.2 to 0.46 Stebar (Ref.l0) 1.3 <.1 = 0.2 only; max.torque spark advance Notes: (1) Instrument resolution not specified C-42 PAGENO="0925" 919 in Fig. C.3-5 are NO~ emissions calculated from peak NO~ con- centrations (equilibrium) for hydrogen fuel-air cycles at a compression ratio of 9/1 (Ref. 18); the cycle efficiencies used in calculating gm/hp-hr from the NO~ concentrations of Ref.l8 were taken from the calculated efficiencies of Ref 17 for CR=9/l. Calculated peak NO~ emissions from gasoline operation are very close to the values shown in the figure for hydrogen (Ref. 18). The NOR-emission data of Fig. C.3-5 (for unmodified engines) do not allow generalization excepting the trivial qualitative observation that emissions can probably ha decreased substantially e.g., an order-of-magnitude, by operation at low equivalence ratio (e.g., ~ .7). This potential for NO~ reduction has often been cited based not only on the limited experimental data but also on the fact of decreased combustion temperature expected at low equivalence ratios. At the equivalence ratios for which hydrogen and gaso- line operation overlap,one set of data (Ref.9 ) show substantially higher emissions with hydrogen (by a factor of two or three or more) for one test engine. However, the data for gasoline op- eration of this test engine are substantially lower (by a factor of three to five) than reference test-engine data cited for gaso- line (Ref. 19). A second set of comparative data (Ref. 10) is available, but only for 80.8) (Ref. 21). Some tests at higher compression ratio (7/1) apparently allowed operation up to somewhat higher ~ (0.85) (Ref.2l), but trends in preignition and backfire were not reported until the work of King (Ref's. 2, 16,22,23). Engine modifications (cool spark plug; aged, sodium- filled exhaust valve) were found to eliminate preignition and backfire at compression ratios up to 10/1 (Ref. 22) and finally to 14/1 (Ref.l6) even for ~E>7. At compression ratios of 16/1 and above, however, preignition was found to persist at engine speeds above 1000 rpm (Ref~. 16) to the limit of testing, 1800 rpm, for .80~~2.3.In con- trast with power output and REP due to combustion, power output and REP due to injected-gas expansion would be expected to in- crease monoto:nically, as was observed. This is because higher and higher ~s require injecting more and more hydrogen at higher and higher pressures. Still another problem in attempting to use Murray and Schoeppels data to interpret the potential and problems of in- jected-hydrogen engines relates to NOx emissions . Fig. C.3-7 shows Murray and Schoeppels NOx data for hydrogen and gasoline in the same engine. For comparison, NOx concentrations from a gasoline test engine (Ref. 19) are shown as well as NO~ concen- trations (equilibrium) calculated at peak cycle temperatures and pressures for both gasoline and hydrogen operation (Ref. 18). C-53 PAGENO="0936" a- C,) z. 0 0 ~n a ~ l0 Lu 0 z 930 EQUIVALENCE RATIO,~ FIGURE C.3-7: UO~ Emissions from H2/Itir, CFI Engine (With Comparison Non-CFI Gasoline- Engine Data) C-54 PAGENO="0937" 931 Comparison of Figure C.3-7 with Figure C.3-5 allows comparison of the data from Murray and Schoeppel's CFI engine with non-CFI Hi-engine data from other workers. In the "high" equivalence ratio range for which gasoline and hydrogen data are reported (0.8 < ~ < 1.1), CFI reportedly yiel~NOx emissions well below Ttypical gasoline test engine data and carburetted-hydrogen- engine operation (see Fig. C.3-7). In contrast, atlowu equiva- lence ratios (where gasoline data are not available), Murray and Schoeppels NO data are considerably higher than more recent data from other hydrogen engines (cp., Fig. C.3-5). Further in contrast, Murray and Schoeppel's data show a weak dependence of NO~ emissions on ~ at low ~ which is quite unexpected thermo- chemically and contrary to the trend exhibited by NOx data from other hydrogen engines. In summary, it appears that owing to the loss of Errens records in World War II and the failure of Murray and Schoeppel to determine indicated power output and to interpret their data in fundamental terms, very little directly useful operating ex- perience is available regarding injected-hydrogen (supercharged) air-breathing engines operated with CFI. C.3.2.f~ - Rotary-Combustion Spark-Ignition Engine The only reported application of hydrogen as a fuel for rotary- combustion (`Wankel") engines is the demonstration project carried out at Brookhaven National Laboratory ("BNL") (Ref s. 32,33). For a demonstration and development of metal-hydride hydrogen storage, the BNL workers have operated a 8 hp. Wankel engine with hydrogen/ air mixtures at several speeds (1000 to 4000 rpm) and loads. Per- formance data are sketchy owing to interest in the engine being peripheral to concern for metal-hydride* storage (Ref. 34). Brake thermal efficiencies and mean effective pressures for this Wankel engine operated on hydrogen are shown in Figs. C.3-l and C.3-2. The equivalence ratios shown were not measured but have been calculated using gasoline data for the same engine. Assuming an equivalence ratio for gasoline operation (~ = 1.1), C-55 PAGENO="0938" 932 the air capacity of the engine can be calculated. Assuming no change in volumetric efficiency, ~`s foi~ hydrogen were calculated from the reported hydrogen supply rates. Low mechanical efficiencies nay be inferred fron the calculated BME~'s and brake thermal ef- ficiencies (compared with the other IMEP's and indicated thermal efficiencies of Fig's. C.3-l, C.3-2). These low values are probably not unreasonable for such a small engine, but lack of data con- cerning friction losses make it uncertain whether these hydrogen Wankel-engine data are actually consistent with other hydrogen re- ciprocating-engine data or not. The BNL hydrogen-fueled Wankel engine operates smoothly and quietly from idle (approx. 900 rpm) to rates speed (4700 rpm). C.3.2.7 - Compression Ignition Engines The only data available concerning operating experience with pure-hydrogen-fueled compression ignition engines is apparently that of Helmore and Stokes (Ref. 35). While, to date this reference has not been obtained and reviewed, Gerrish and Foster (Ref. 36) describe some of Helmore and Stokes' results. While most dis- cussion of these results is postponed to a later section on com- bined-fuel operation, some of the combined-fuel results are rele- vant to pure-hydrogen compression-ignition operation. Since these combined-fuel investigations apparently involved homogeneous rather than injected hydrogen/air mixtures, the following observations relate only to homogeneous-charge compression-ignition engines ,not to common,injected, "Diesel" engines. There are apparently no data available from hydrogen-injection, compression-ignition engines. Helmore and Stokes operated with combined fuel (90% hydrogen/ 10% fuel oil) only after violent detonation resulted during an attempt to burn pure hydrogen at CR=ll.6/l. Unfortunately, Gerrish and Foster's citation is not clear on operating conditions for these tests. Detonation at nine-tenths" full power appears to imply ~=0.9 or perhaps slightly less. Helmore and Stokes' "detonation" was presumably autoignition and, according to Karim's data on violently knocking autoignition, a maximum CR of about 13 is allowable without violent knock and C-56 PAGENO="0939" 933 autoignition. Especially since such. phenomena are dependent on configuration and test conditions, the differences between Karims limit of 13 and Helmore and Stokes 11.6 (at high~) are probably inconsequential. It appears that compression-ignition `engines em- ploying homogeneous mixtures are not practical owing to autoigni- tion at least for ~ approaching 1. It must be noted at CR's ex- ceeding approximately 12/1 that elevated intake temperatures may decrease this CR substantially, judging from Karims data (Ref. 25). Combined-fuel operations also have implications regarding pure-hydrogen operations. At compression ratios of 13.4/1 and 15.6/1 (Ref. 36), Gerrish and Foster found that hydrogen equiva- lence ratios could not exceed about 0.5 and 0.4,respectively, without preignition or backfire when small pilot changes fo fuel oil were injected (equivalent to ~ = .022). This behavior fuel oil may reflect the same phenomenon studied by King et al (Ref. 16) who found preignition and backfire attributable to solid carbon particles. However, at ~ of 0.5 and 0.4, homogeneous hydrogen/ air mixtures would not compression-ignite without at least an exceedingly small pilot charge, for CR=13.4/l and 15.6/1, re- spectively. The implication is that somewhere in the range 0.5~('I <0.9, homogeneous compression-ignition operation is impractical for CR above about 14 or 15/1. This observation is consistent with Kings observation in spark-ignition engines that backfire and preignition could be eliminated at CR=l4/l but occurred at CR»=l6/l for ~»=0.8. Owing to lack of operating experience data, no generalizations can be made concerning injected-hydrogen compression-ignition engines. C.3.3 - Hydrogen/Oxygen Engines While a number of proposals for H2/02 reciprocating engines have been made (e.g., Ref's. 37,38), operating experience is very limited and performance data sketchy. One of the most documented experiences is the development by Vickers, Inc. of an auxiliary power unit ("APU") for space application (Ref's. 39,40). An H2/02 recip was considered promising for space application because of C-57 PAGENO="0940" 934 its high specific power (small volume) and low specific weight. Otherwise, operations have apparently been limited to exploratory experiments and demonstrations rather than substantial performance testing (Ref. 41). Table C.3-6 summarizes the engine specifica- tions and operating conditions for these 112/02 engine operations. Also Table C.3-5 summarizes the performance data reported. Since there is virtually no data available from the experiments of the Perris Smogless Automobile Assoc. (Ref. 41), further consideration is limited to the operatiom of the APU. The Vickers APU was operated with °2 and 112 injection and vacuum exhaust (for space application) and shows high specific power (4.75 bhp; 1.75 bhp/in3, max.), brake thermal efficiency (0.32, max.) and bmep (173 psi, max.). Corrected by Vickérs data for friction power, these data imply the maximum indicated power, specific power, efficiency, and MEP cited in the table. An ad- ditional correction is required to correct vacuum-exhaust opera- tion to the more conventional ambient-exhaust conditions; with ambient exhaust, work is lost to compression of the exhaust residual by reactant injection. For the compression ratio used (12.7/1), however, this represents a negligibly small correction compared with that for the expansion work of the high-pressure- injected reactants (which is~ included in the brake thermal ef- ficiency calculations by Vickers). The APU engine was operated hydrogen-rich (l.4'~ ~ ~7.0) and was run over a range of speeds (2000 to 4000 rpm), indicated pOwer outputs (0.75 to 5.28 hp), indicated MEP's (55 to 192 psi), and indicated thermal efficiencies (0.125 to 0.356) without exceed- ing design limits on cylinder-head temperature (apparently approx. 1400°F at an unspecified location). Heated hydrogen (500°F) was injected first at various supply pressures up to 400 psi followed by ambient-temperature oxygen at unspecified pressure (apparent- ly 500 to 600 psi). Injection timing~ was not optimized. It appears that ~2 was determined in each run as the minimum (~>l) consistent with maximum allowable head temperature. C-58 PAGENO="0941" TABLE C.3-Sa: SU~DIARY OF HYDROGEN/OXYGEN ENGINE EXPERIENCE - ENGINE SPECIFICATIONS PONER OUTPUT INVESTIGATOR NO. OF CYLINDERS DISPLACE- MENT COMPRESSiON RATIO MAX. ENGINE MAX. PISTON MAX. REPORTED MAX. POWER DISPLACEMENT MAX. POWER PISTON AREA SPEED SPEED POWER (IN3) (RPM) (FT/MIRM (lIP) (HP/IN3) (HP/IN2) Morgan (Ref. 40) E 2.72 12.7/1 4000 1025 5.15 1.9 3.0 Underwood Various, few detaiEs given (Ref. 41) TABLE C.3-Sb: SUIIIARY OP hYDROGEN/OXYGEN ENGINE EXPERIENCE - PARTIAL PERFORMANCE DATA AT MAX. REPORTED POWER AT MAX. REPORTED EPPIC. INVESTIGATOR EQUIV. THERMAL MEP EQUIV. THERMAL MEP PERFORM- RATIO, B EFFIC., RATIO, B EFFIC., ANCE (1) (PSI) (%) (PSI) CURVES? Morgan 6. .32(1) 190(2) . Same as Max. Power Yes (Ref. 40) Underwood - - - - - No (Ref. 41) NOTES: (1) Based on available 02 in (rich) mixture and includes, as input, expansion work of H2 su~plied at 400 psig. (2) Includes effect of expansion work by H2 supplied at 400 psig, 02 supplied at approx. 50 psig. C-59 PAGENO="0942" 936 Since operations were with~>1, excess hydrogen acted as a diluent. Reported efficiencies were calculated as the ratio of power output to maximum available chemical energy (oxygen limited for ~l) ~ the ideal expansion work available from the in- jected hydrogen. The potential expansion work of injected oxygen was not included though it appears to be comparable to that of injected hydrogen. Depending on operating conditions, varying fractions of available power (combustion plus expansion) were attributable to 112 expansion: from about 5% (~ = 1.4) to about 15% (~= 6). It is reasonable to base the calculation of available com- bustion energy on the heavier reactant,ox~'gen, in space applica- tion where weight is a prime factor. In other applications, however, hydrogen cost or volume might be more significant,im- plying a need for efficiencies based on hydrogen supply rates and their associated potential for energy release through com- bustion. On the basis of hydrogen supplied, the reported effici- encies would apply only if excess hydrogen were recycled from the exhaust stream. Otherwise, efficiencies would be considerably lower than those reported: .~ 1 ~2 supplied - (02 supplied i.e., for the reported maximum indicated efficiency (O.3g) at = 56.0: ~H2 supplied = (0.32) = 0.053 Two alternatives exist to that of limiting operating tempera- tures in 112/02 engines by using excess hydrogen (~>l). First, excess oxygen might be used (~ 400 where D = H+F = structural or hull weight (LI) D = depth (ft) L = water line length (ft) B = beam (water line) (ft) H = draft (molded) (ft) F = freeboard (ft) Figure 3-1 is a graph of the structural weight data and Equation (3-1). Hydrofoils are modele~as constant structural density boxes using the relation: W~(hydrofoil) = 9.8 x lo~ L B D . (3-2) The SES is modeled with the following structural weight equation: Ws(SES) = 1.34 x 10~ SC HE where 2 S~ = cushion area (ft HE = average effective height (ft) The enc1ose4~ hull volumes for the dynamic lift ships are found by dividing their structural weights by their average structural densi- ties, 2.5 lb/ft3 for hydrofoils and 3.0 lb/ft3 for the SES (Heller and Clark, 1974). For displacement ships the enclosed hull volume, V5, is approximated by the sum of the underwater hull folume, given by the displacement, 1~, multiplied by the specific volume of sea water, and the product of the water plane area, A~qp, and the freeboard: V~(disp1acoment) = 35 A + F . (3-4) 60 PAGENO="1025" 0 C\J 4-, 4- I~j 0.15 0.10 0.05 0 200 400 800 L (ft) Figure 3-1. Structural weight of displacement ships. PAGENO="1026" 1020 The water plane area is approximated as follows (Whitten, 1966): A~ = L B (0.18 + 0.88 C~) (3-5) where Cp is the prismatic coefficient. To calculate the powering requirements for the rigid sidewall SES, the cushion area and skirt circumference are needed. The shape of the water plane is taken as rectangular with a semicircular bow. The cushion area, SC, is Sc = (L~)B + !~_. (3-6) and the skirt circumference, cs, is C5 = B+~B . (3-7) If the gap height is H,~, then the gap area, SG, is given by SG = CS HG (3-8) Dyhamic Model The purpose of the dynamic model is to provide ship propulsion powering data for calculating fuel requirements. For dynamic lift ships, the lifting power is included. Hotel loads and auxiliary power are not included. The major sources of drag for displacement ships are frictional or profile drag at low speeds and residual or wave drag at high veloc- ities. For high s~eed ships such as the PF and DD, the use of Series 64 hull data (Yeh, 1965) is appropriate. Table 3-2 presents the form parameters fo~ the residual resistance data used for the study. The frictional resistance is calculated with the Series 64 wetted surface area relation (Yeh, 1965) and the ITTC resistance coefficient (Gillmer, 1970) to which is &~ded a correlation allowance of 0.0006. For the fuller, slower vessels, ie, the SCS, LIlA, and CVX, the Taylor Standard Series resistance data are appropriate. Table 3-3 shows the form parameters for the residual resistance data employed (Barnaby, 1960). The ITFC resistance coefficient with a 0.0006 correlation allowance is used with a modified form of Taylor's formula for the wetted sur- face area, SW (Barnaby, 1960) SW = (12.5 + ~.) ~t . (3-9) 62 PAGENO="1027" 1021 Table 3-2. Form parameters for the Series 64 resistance data used. *Parameter Definition Range C8 block coefficient 0.45 -k ~ (0.01 L) displacement ratio 20 to 45 j~- beam draft ratio 2 to 4 vf~ speed length ratio 0.2 to 5.0 C~, prismatic coefficient 0.63 Table 3-3. Form parameters for the Taylor Standard Series data used. Definition Range displacement ratio 50 to 250 beam draft ratio 2.25 to 3.75 prismatic coefficient 0.50 to 0.80 speed length ratio 0.60 to 1.10 The relations for the drag of subcavitating, submerged hydrofoils at Froude numbers above 1.5 are adapted from Mandel (1969). The pro- file drag is given by 2 pV D~(hydrofoil) = C0 S -~-- (3-10) 63 PAGENO="1028" 1022 where D~ = profile.drag (Ib) CD = drag coefficient S = effective surface area (ft2) = density of sea water (slug/ft3) V = velocity (ft/sec) A drag coefficient (including both profile and spray resistances) of 0.013 is used. The hydrofoil residual drag is given by D - (W/A) 2240 t~' 3 11 R ~~7rap~V2 N ) where DR = residual drag (lb) W/A foil loading factor (lb/ft2) = dynamic takeoff lift weight (LT) a = foil aspect ratio Since the hydrofoil modifications involve only hull changes at constant weight, the foil parameters are kept unchanged. Nominal values of 6 for the foil aspect ratio and 1200 for the foil loading factor are used. The dynamic takeoff lift weight is the weight of the vessel corrected for the buoyant lift of the submerged foils and structure. Takeoff lift weights of 225 LI for the PW4 (based on the data of Duff, 1972) and 1255 LI for the DEH (Aroner and Hubbard, 1974) are used. The powering model for the SES includes both propulsive and lift components. The profile drag, D~, is calculated as 2 pV D~(SES) = CD S~ -~--- , (3-12) with a value of 0.10 for the profile drag coefficient, CD (Handel, 1969). Wave drag calculations employ Equation (3~l2) with the wave drag resis- tance coefficient, C~, in place of CD. The velocity dependence of C~ is shown in Figure 3-2. The ideal cushion power required for lift (Handel, 1969) is given by 1/2 ~C,i = 5G Dc(~) (LW)3~~2 (343) 64 PAGENO="1029" 1023 04 ~ 10 w FROUDE NUMBER, FN Figure 3-2. Wave drag coefficient for surface effect vehicles (Mandel, 1969). 0.1 1 10 65 PAGENO="1030" 1024 where PC ~ = ideal cushion power (ft lb/sec) SG = gap area (ft2), Equation 3-8 DC = discharge coefficient 3 = air density (slug/ft = 2240 ti/Sc = cushion pressure (lb/ft2) and SC is given by Equation (3-6). Constant values of 0.60 for the discharge coefficient and 0.75 ft for gap height are used. Table 3-4 lists the propulsive coefficients. The propeller values are for subcavitating screws. An efficiency of.0.5 is assumed for the lift fans on the SES. Table 3-4. Propulsive coefficients modeled. Propulsor Propulsive Coefficient Reference Single screw 0.2084 + 0.0618 £n(L) (Barnaby, 1960) Twin screw 0.1550 + 0.0630 &n(L) (Barnaby, 1960) Quadruple screw 0.0875 + 0.0626 £n(L) (Barnaby, 1960) Water jet 0.45 (Bodnaruk 1973) and Quandt, Variational Methodology The wide variation in the physical properties (such as the mass and energy densities) of the candidate ship fuels does not permit the use of a single ship design for all the fuels. The procedure chosen is to modify the DR.! fueled designs maintaining several parameters as variational constraints; the most important of these is the displace- ment. Basically, the procedure is to maximize the fuel capacity by varying the structural volume and weight subject to the constraints, assuming that any changes in the hull volume accrue to fuel storage. The four variables or dimensions that are changed are the water line length, L, the beam, B, the draft, H, and the freeboard, F. Since the displacement is constant and the block coefficient is taken as an invariant, the product LBS is therefore constant. The fineness ratio, L/B, is selected as another invariant. The third invariant, chosen to reflect static stability, involves a model for the meta- centric height. 66 PAGENO="1031" 1025 The distance of the metacenter above the center of buoyancy, BM, is given by (Gillmer, 1970): L2 3 - f~rdx = v (3-14) where V = displacement volume (ft3) r = half breadth of ship (ft) dx = increment along ship length (ft) If a constant density rectangular box ship model is used for deter- mining the stability criterion, one finds that V = LBH (3-15) and 2 = . (3-16) The keel to center of buoyancy distance, KB, is = 4i~ (3-17) and the keel to center of gravity, KG, is = 4 (HiP) . (3-18) Combining Equations (3-16) to (3-18) gives the metacentric height, ~: B2 F = ~-~- . (3-19) As shown above, the four dimensional variables, L, B, H, and F, are related by three equations when the displacement, fineness ratio, and metacentric height are held constant. The DFM-fueled ship is used as a baseline design to provide values for these constants. Each syn- thetic fuel modification is found by treating the beam of the baseline version as an independent variable, and adjusting it to maximize the resultant fuel capacity. Note that the three remaining dimensions, L, H, and F, are functions of the bean through the three constraint equations. 67 PAGENO="1032" 1026 The procedure outlined fails in the case of the SES because the volume displacement and metacentric height are defined only as dis- placement ship quantities. Therefore, for the synthetic fuel varia- tions of the SES, the freeboard or average height is varied to maxi- mize the fuel capacity. BASELINE SHIP CHARACTERISTICS The dimensions and performance for the DFM-fueled ships are given in Table 3-5. Here L is the waterline length, B is the waterline beam, H is ship draft, and F is ship freeboard with all dimensions in feet. The ship propulsor used in the analysis is shown along with the. brake horsepower in multiples of 20,000 HP required to achieve the maximum speeds listed. The DFM fuel weight chosen for each ship is given, as is the range the ship can achieve at 90 percent of this fuel load at the indicated cruise speed. Ranges are rounded to the nearest 50 nm. The selection of dimensions and performance criteria for the DFI4- fueled ships was dictated by a number of criteria: the availability of pertinent ship design data in the open literature, the need to maintain internal consistency within the model, and limitations im- posed by the model formulation. For the dynamic lift ships, the di- mensions and other features selected generally correspond to those for specific ships discussed in the literature. For displacement ships, the choice of dimensions and performance criteria was dictated by factors discussed in the second subsection following. Where cer- tain data were not readily available, such as freeboard dimensions, reasonable estimates were made consistent with the model formulation. Dynamic Lift Ships The PHM characteristics are derived from descriptions of both the NATO and U.S. versions of this ship, using the somewhat larger initial fuel load of the U.S. version (Duff, 1972; Heller and Clark, 1974). The maximum speed shown in Table 3-5 is that computed by the model as is the range at the indicated cruise speed. This range is greater than that quoted for the NATO PF~4 (Boehe, 1973) reflecting the larger design fuel load and the fact that the range quoted in the table does not include any degradation due to rough water as does the range value given for the NATO PHM. The dimensions for the DElI are given by Aroner and Hubbard (1974). The power requirement given by the model, however, is roughly a factor of two higher than that given in this reference and the range is about 30 percent lower. The model ranges do agree to within about 5 percent with that calculated for a hydrofoil of about the same gross weight and payload (Jewell, 1974). In order to account for the increased power required over the published design (Aroner and Hubbard, 1974), the 68 PAGENO="1033" Table 3-5. Dimensions and performance of the representative DFM-fueled ships. Ship L (ft) B (ft) H (ft) F(ft) Propulsor Power (HP) Maximum Speed (KT) DFM Fuel Weight (LI) Cruise Speed (KT) Range at a) Cruise (NM~ PHM 118 24.6 6.2 8.3 Water jet 20,000 55 41 30 1,350 DEH 200 40.5 12.0 16.0 1 screw 80,000 52 456 30 3,150 SES 245 105 -- 18.9 Water jet 120,000 98 775 80 4,000 PF 406 41.5 13.8 14.2 1 screw 40,000 31 315 20 4,000 DD 511 52.3 17.5 17.9 2 screws 80,000 33 650 20 5,000 SCS 612 78.9 22.6 52.8 1 screw 40,000 27 1320 20 12,000 LHA 794 98.6 26.3 56.7 2 screws 80,000 25 2570 20 10,000 CVX 902 114 32.8 58.9 4 screws 200,000 31 3650 20 11,950 (a) Range based on 10-percent fuel reserve rounded to nearest 50 nm. PAGENO="1034" 1028 power plant weight for the study ship was doubled with the 90-ton weight increment being charged against the DFM fuel load. The SES dimensions, gross weight, powering requirement, and DFM fuel load are taken from Davis (1974). These dimensions and weights represent averages of several designs for the SES. The lift power requirement as determined by the model is 36,500 HP. In addition, four nominal 20,000 HP gas turbines are required for propulsion to achieve the indicated 98-kt maximum speed. Several other items pertaining to Table 3-5 should be mentioned. The gas turbine SFC is assigned a constant value independent of tur- bine power output for several reasons. First, a power-dependent SFC would unnecessarily complicate the interpretation of the fuel consump- tion results. Second, the use of a cruise turbine or less than the full complement of main turbines permits operation at full turbine power resulting in peak efficiency and minimum SFC for a number of speeds. Hence, the SFC values used for the various fuels represent the optimum for minimizing fuel consumption. The fu~l consumption calculations represent propulsion (and lift) burdens only. The effects of auxiliary power generation, such as the hotel load, are not treated. Range calculations are based on the consumption of only 90 percent of the available fuel. The assumption of the 10-percent fuel reserve is not only coimnon practice but, in the case of the cryogenic fuels, serves the additional duty of maintaining the tanks at low temperature so that the chill-down process is avoided. The range calculations reported here utilize a constant full-load displacement or weight rather than the decreasing weight reflected by the Breguet logarithmic range equation. This results in a slightly conservative estimate of range. Displacement Ships The factors involved in establishing the baseline, DFM-fueled, dis- placement ship characteristics are based on general considerations of size and weight class rather than the specific approach taken for the dynamic lift ships. For each representative ship, the length and beam are characteristic of the type and weight class, and the draft is determined by adopting a block coefficient similar to that of ships of the same class. The freeboard was determined both from estimates of the metacentric height of comparable weight ships (a function of freeboard and draft) and from analytical approximations given in the literature (Whitten, 1966). The powering requirements reflect both the estimates of maximum speed for the particular type of ship and the choice of gas turbine propulsion. 70 PAGENO="1035" 1029 Further constraints on selection of dimensions were imposed by the choice of a hull form for each ship. For the PF and DD, a Series 64 hull form is assumed as these data are most appropriate for fast, sleek-lined surface combatants. For the SCS, LHA, and CVX, Taylor Standard Series data are more appropriate in determining powering requirements. These tables are a function of ship displacement, length, beam, speed, and block and prismatic coefficient, and are applicable only over certain ranges of these parameters. The dimen- sions and other features selected for the baseline displacement ships reflect consideration of all of these factors. For the 3000-ton PF modeled in the study, the dimensions and other features of the 3400-ton PF now in construction and other ocean escorts in this class are used as a guideline (Moore, 1973). For the 6000- ton DD, the 5800-ton DLG-9 and other comparable destroyers provide model data (Miller, 1972). The description of the SCS (Price, 1974) provides estimates of its dimensions, and data for the LHA-l (Moore, 1973) establishes the LHA characteristics modeled in the study. For the CVX, a Midway-class carrier, CVA-4l (Moore, 1973), provides ini- tial sizing of the study ship. Once the displacement ship dimensions, maximum speed, and powering requirements are specified, the DFM fuel load is determined by requir- ing that the ship be able to achieve a particular range at a typical cruise speed. The required fuel load to achieve this range at the indicated speed is given in Table 3-5. These ranges are comparable with those of other ships in the same class or are representative of the mission for which the ship is designed. MODIFIED SHIP CHARACTERISTICS Tables 3-6 through 3-13 show the model-derived characteristics of the ships modified to use synthetic fuels. The results for the DFM- fueled version are included for comparison. The ranges given at the indicated speeds all reflect an allowance for a 10-percent fuel re- serve. For ammonia and methane, results are given for both the light and heavy fuel tank designs discussed in Section 2. It can be seen from the tables that hydrogen and methane perform about as well as diesel fuel. For the larger ships, ie, the LHA and the CVX, the cryogenic fuel ranges may be extended by using larger, and hence less volume and weight wasteful, fuel tanks. The mixed methylamine fuel is not as good as DFM for any of the representative ships, but it does provide at least 75 percent of the DR.! ranges. In all the cases considered the ammonia, hydrazine, and methanol modifica- tions provided significantly shorter ranges than the DFM-fueled ship. REPRESENTATIVE NAVAL AIRCRAFT This subsection presents preliminary estimates of one aspect of the performance of aircraft using synthetic fuels. Two representative 71 PAGENO="1036" 1030 Table 3-6, Variations.of the P1*1. H 5.6 Fuel Fuel Weight (LT) L B 26.0 F 12.2 Range at3OKT (NM) Range at55KT (NM) H2 20.6 124.5 1900 1000 NH3/L 38.9 118.7 24.8 6.1 8.7 550 300 NH3/H 37.6 118.5 24.7 6.1 8.6 550 300 300 N2H4 41.2 117.9 24.6 6.2 8.2 550 CH4/L 36.7 119.6 24.9 6.0 9.2 1400 750 CH4/H 34.2 120.2 25.1 6.0 9.6 1300 700 CH3OH 40.8 118.1 24.6 6.2 8.4 650 350 NMA 39.3 118.6 24.7 6.1 8.6 1050 550 DFM 41.0 118.0 24.6 6.2 8.3 1350 700 Table 3-7. Variations of the DEH. Fuel Range Range Fuel Weight (LT) L B H F at3OKT (NM) at50K~ (NM) H2 228.0 224.7 45.5 9.5 29.5 4450 2600 NH3/L 434.6 203.3 41.2 11.6 17.5 1350 750 NH3/H 418.0 202.3 41.0 11.7 17.1 1300 750 N2H4 460.7 199.5 40.4 12.1 15.8 1250 750 CH4IL 408.5 206.9 41.9 11.2 19.3 3350 1950 CH4/H 377.6 209.2 42.4 11.0 20.5 3100 1800 CH3OH 451.2 200.5 40.6 11.9 16.2 1500 850 MMA 434.6 202.7 41.1 11.7 17.3 2500 1450 DFM 456.0 200.0 40.5 12.0 16.0 3150 1800 72 PAGENO="1037" 1031 Table 3-8. Variations of the SES. Fuel Fuel Weight (LI) L B 105.0 - H --- - F 28.5 Range at 80K1 (NM) Range at 98KT (NM) H2 359.2 245.0 5200 5150 NH3/L 734.6 245.0 105.0 --- 19.9 1650 1650 NH3/H 710.4 245.0 105.0 --- 19.6 1600 1600 N2H4 775.0 245.0 105.0 --- 18.7 1550 1550 CH4/L 682.2 245.0 105.0 --- 21.1 4150 4100 CH4/H 625.7 245.0 105.0 --- 21.9 3800 3750 CH3OH 771.0 245.0 105.0 --- 19.0 1850 1850 MMA 730.6 245.0 105.0 --- 19.7 3100 3100 DFM 775.0 245.0 105.0 --- 18.9 4000 3950 Table 3-9. Variations of thePF. Fuel Range Range Fuel Weight L B H F at 20 KI at 31 K (LI) 43.2 12.7 (NM) (NM) H2 114.8 422.7 17.8 4550 1750 NH3/L 311.7 406.5 41.6 13.8 14.3 1750 650 NH3/H 305.2 405.7 41.5 13.8 14.1 1700 650 N2H4 347.8 403.1 41.2 14.0 13.6 1750 650 CH4/L 278.9 409.7 41.9 13.6 15.0 4350 1650 CH4/H 246.1 411.6 42.1 13.4 15.4 3850 1450 CH3OH 341.2 404.0 41.3 13.9 13.8 2050 800 MMA 315.0 406.0 41.5 13.8 14.2 3350 1250 DFM 315.0 406.0 41.5 13.8 14.2 4000 1550 73 PAGENO="1038" 1032 Table 3-10. Variations of the DD. Fuel Fuel Weight (IT) I B H F Range at 20 KT (NM) Range at 33 K~ (NM) H2 206.5 532.1 54.5 16.1 - 22.5 4850 1650 NH3/L 582.3 514.4 52.6 17.3 18.6 2000 650 NH3/H 572.1 513.5 52.6 17.3 18.4 1950 650 N2H4 663.5 510.5 52.2 17.5 17.8 2000 650 CH4/L 514.6 518.0 53.0 17.0 19.4 4850 1600 CH4/H 457.0 520.1 53.2 16.9 19.8 4350 1450 CH3OH 639.8 511.5 52.4 17.5 18.0 2300 800 MMA 589.1 513.8 52.6 17.3 18.5 3800 1250 DFM 650.0 511.0 52.3 17.5 17.9 5000 1650 Table 3-11. Variations of the SCS. - - Fuel Fuel Weight (LT) L B 81.2 H 21.3 F 58.5 Range at 20 KT (NM) Range at 27 K~ (NM) H2 495 630.1 11400 5800 NH3/L 1306 612.5 79.0 22.6 52.9 5200 2400 NH3/H 1279 611.7 78.9 22.6 52.7 5100 2350 N2H4 1444 609.0 78.5 22.8 51.9 5200 2400 CH4/L 1169 615.8 79.4 22.3 53.9 12450 5800 CH4/H 1045 617.9 79.7 22.2 54.6 11000 5200 CH3OH 1430 610.0 78.6 22.7 52.2 6150 2850 £~1A 1320 612.0 78.9 22.6 52.8 9950 4600 DFM 1320 612.0 78.9 22.6 52.8 12000 5550 74 PAGENO="1039" 1033 Table 3-12. Variations of the LHA. B F Fuel FueL Weight (LT) L H Range at 20 KT (NM) Range at 25 KT (NM) H2 1037 813.4 101.0 25.1 62.9 10500 5750 NH3/L 2543 794.5 98.7 26.3 56.9 4350 2200 NH3/H 2490 793.7 98.6 26.3 56.6 4250 2200 N2H4 2784 791.1 98.2 26.5 55.8 4300 2200 CH4/L 2302 797.9 99.1 26.0 57.9 10550 5400 CH4/H 2075 799.9 99.3 25.9 58.6 9400 4900 CH3OH 2731 791.9 98.3 26.4 56.1 5050 2550 MMA 2570 794.0 98.6 26.3 56.7 8300 4250 DFM 2570 794.0 98.6 26.3 56.7 10000 5100 Table 3-13. Variations of the CVX. Fuel - Range Range Fuel H2 Weight (LT) L B 11L9 H F 65.9 at 20 KT (NM) at 31 KT (NM) 1369 924~9 31.2 - l1350 3900 NH3/L 3612 902.7 114.1 32.8 59.1 5200 1600 NH3/H 3536 901.6 113.9 32.8 58.8 5100 1550 N2H4 4030 898.3 113.5 33.1 57.8 5250 1600 CH4/L 3232 906.8 114.6 32.5 60.3 12400 3850 CH4/H 2890 909.5 114.9 32.3 61.1 10950 3450 CH3OH 3916 899.4 113.7 33.0 58.1 6050 1850 lilA 3650 902.0 114.0 32.8 58.9 9900 3050 DFM 3650 902.0 114.0 32.8 58.9 11950 3650 75 PAGENO="1040" 1034 aircraft are examined: a light attack aircraft (VA), and a vertical! short takeoff and land aircraft (V/STOL). The specifications assumed for the JP-5 fuel configurations of these aircraft are shown in Table 3-14 based on the A-7E and AV-8A as prototypes of the VA and V/STOL, respectively (Taylor, 1973; Aviation Week, 1974). Because of weight constraints on combat aircraft, only the cryogenic fuels (liquid hydrogen, liquid methane) are considered feasible replacements for JP-5; design modifications for the other synthetic fuels are not in- vestigated in detail. The approach taken uses constant stored fuel energy as its goal, and obtainsestimates of the necessary volume and weight increases which result. Both constant takeoff weight and constant payload weight configurations are examined. The level flight performance penalties associated with the lift and drag increases are then evalu- ated. The results indicate that small but significant performance degradation is associated with the modifications required by the cryogenic fuels. Method of Aircraft Analysis The purpose of this investigation is to estimate the performance of Navy tactical aircraft modified to operate on synthetic fuel. The modifications considered are those necessary to carry the additional fuel volume needed to store the same total fuel energy. The potential utility of the cryogenic fuels for either engine or cabin and avionics cooling is not considered. The performance characteristics evaluated are steady state parameters; no accelerated flight or maneuvering-per- formance is treated. Hence, the estimates are based on balancing lift with weight and thrust with drag. The thrust generated by a given fuel and engine combination may be expressed as T = r)mf(Hf+V2/2)/V rimfHf/V (3-20) where T is the thrust, V the aircraft velocity, mf the fuel mass flow rate, Hf the heat of combustion of the fuel, and 11 the overall power- plant efficiency (Foa, 1960). The approximation results from neglect of the fuel kinetic energy; it is a satisfactory one for the systems under consideration. For an unchanged engine design and air flow rate at a given flight velocity, different fuels will produce the same power as long as mfHf is constant. A direct measure of the fuel storage volume required to maintain constant total energy with the synthetic fuels follows from the volu- metric fuel flow rate v. = (mf)./P. , (3-21) 76 PAGENO="1041" 1035 Table 3-14. Aircraft specifications. - VA - V/STOL Wing chord at root, c0(ft) 15.5 11.67 Wing chord at tip, cT (ft) 3.85 1.13 Wing thickness, tmax (in.) 13.0 14.0 Wing aspect ratio, A 4.0 3.2 Mid chord sweep angle, 4 (deg) 35.0 34.0 Wing area, S (ft2) 375.0 200.0 Fuselage length, L (ft) 46.0 45.0 Fuselage diameter, D (ft) 4.5 4.0 Empty weight, Wg (lbf) 18,400.0 12,200.0 Armament weight, Wa (lbf) 15,000.0 8,000.0 JP-5 fuel weight, Wf (lbf) 9,300.0 5,100.0 Maximum takeoff weight, Wmax (lbf) 42,700.0 25,300.0 Engine weight, We (lbf) 3,180.0 3,660.0 Maximum thrust, Tmax (lbf) 15,000.0 21,500.0 Thrust specific fuel 0.64 0.70 consumption, y (lbm/hr/lbf) Maximum velocity (sea level), 600.0 640.0 Vmax (knots) 77 62-332 0 - 76 - 66 PAGENO="1042" 1036 where p~ is the mass density of the ith fuel. Constancy of the term mfHf then requires that - (P~)jp_5 JP-5 fi and constancy of total fuel energy requires that the volume ratio of stored fuel be identical to the volumetric flow rate ratio. Because the fuels considered are cryogenic and require insulated storage and piping, it is unlikely that much fuel can be stored in the thin wings of military aircraft. For liquid hydrogen, the uncertain- ties in state of the art of small aircraft tank design lead to the conservative approach of assuming that all of the fuel must be stored in fuselage tanks. Liquid methane, on the other hand, has a much higher temperature than liquid hydrogen and can be stored in small, lightweight tanks (Chambellan et al, 1967). As a result, wing, tanks probably can be used for methane if the fuel management program dic- tates that the wing tank supply is used first. Thus, using the as- sumptions of (1) no wing tank storage for hydrogen, (2) the same wing tank storage for methane as for JP-5, and (3) 25 percent of the JP-5 supply in wing tanks, the additional fuselage volume, EN, required for the synthetic fuels can be estimated from the required fuel volumes. For the volume estimates, the fuselage is approximated by a right cir- cular cylinder, and the ratio of length to diameter (fineness ratio) of the enlarged fuselage is taken as that of the original fuselage. The resultant aircraft weight change is a consequence of two ef- fects: the change in fuselage weight and the change in fuel system weight. The first effect depends on fuselage size. Since fuselage expansion for additional tankage does not affect the main structural components that transmit the wing loads through the fuselage, the additional walls involved are probably designed by minimum gage re- quirements rather than bending moment requirements. Thus, the weight change can be estimated by dimensional expansion as being proportional to the surface area change (Shanley, 1952): Wb - Wb(V/V) (3-23) where Wb `is the fuselage weight after modification, Wb is the unmodi- fied fuselage weight, and V and V the new and old volumes. Fuselage weight is estimated from component weight ratios of a variety of air- craft by the approximation Wb/(Wg_We) 1/3 (3-24) 78 PAGENO="1043" 1037 where W2 is the gross weight of the empty aircraft and We is the engine weight `(Fry, 1966; Hoerner, 1969). The fuel system weight effect may be expressed in terms of the fuel system weight fraction, F5f = Wi/Wf (3-25) where W~ is the fuel system weight for the ith fuel and Wf is the fuel weight. Estimates of F5f have been given as 0.03 for hydrocarbon, 0.10 for methane, and 0.8 for hydrogen (Esgar, 1970; Greenburg, 1969). Equations (3-23) through (3-25) lead to = (Wg_We)(1+Exv/v)2/3 + (WfF5f)~ - O.O3(Wf)Jp + We (3-26) for the reconfigured dry gross weight. If the aircraft wings are not modified, then wing loading consider- ations require that the maximum takeoff weights given in Table 3-14 re- main fixed. Adding the empty gross weight and the fuel weight and sub- tracting the total from the maximum takeoff weight then yields the to- tal armament weight for each aircraft/fuel combination. The alternative choice of maintaining a fixed armament payload and increasing the wing area is also of interest. For this purpose, the wing weights, ~ are needed. The specific wing weights, Wy/S, where S is the wing area, can be estimated from data of Heath (1969) and the wing geometry (Table 3-14). The resulting estimates are 10 lbf/ft2 for attack aircraft and 7 lbf/ft2 for V/STOL aircraft. Taking both fuselage and wing modifications into account, the reconfigured, con- stant payload aircraft then has a maximum weight W = 31 + W + W + (W IS) ~S (3-27) max g f a w' where Wa is the armament weight and ~S is the additional wing area re- quired. Under the assumption of a constant ratio of takeoff weight to wing area, Wmax is also given by 31max = (S+z~S)(W/S) (3-28) where Wama is the maximum takeoff weight of the hydrocarbon configura- tion. Equations (3-27) and (3-28) yield the relative wing area in- crease in the form AS/S = (Wg+Wf+Wa_Wmax)/(Wmax~Ww) . (3-29) 79 PAGENO="1044" 1038 The lift and drag are given by L = qC~S (3-30) D = qC~S (3-31) where q is the dynamic pressure and CL and CD are the lift and drag coefficients, respectively. The drag coefficient can be approximated by CD = CD + C~/7rAe (3-32) f where CD is the parasite drag coefficient, A is the aspect ratio, and e, t~e airplane efficiency factor, is roughly constant from air- plane to airplane at a value of about 0.75 (Perkins and Hage, 1956). Equation (3-32) shows that the induced drag coefficient will be un- changed if A is unchanged. Consequently, it is assumed that wing area changes are made at constant aspect ratio. The effect of the wing area, 5, and the fuselage cross-sectional area, Ac, on the parasite drag coefficient can be estimated by de- fining an equivalent parasite drag area, f, as the sum of the fuselage parasite drag area, ff, and the parasite drag area for the remaining portions of the aircraft, fr: f = C S = f + f (333) Df f r Since most of the nonfuselage parasite drag comes from the wings, S is the proper area for the drag contribution ~r and the drag coefficient CDr = fr/S - (3-34) is assumed to be unaffected by a fuselage change. Similarly, the par- site drag coefficient for the fuselage is based upon Ac and is cus- tomarily denoted by CD~: CD = ff/Ac (335) This proper fuselage drag coefficient has been studied for a number of aircraft, and its variation with the fuselage fineness ratio, 2., as shown by Perkins and Hage (1956) is well represented by 80 PAGENO="1045" 1039 CD = 0.0175(1+0.483 i) . (3-36) 71 Thus, at constant fineness ratio, it too is unaffected by fuselage change. The effect of these drag considerations appears directly in the thrust calculations where the thrust required is estimated by setting drag equal to thrust and lift equal to weight. Using the definition for dynamic pressure q = pV2/2 , (3-37) there results T = aV2 + 8/V2 (3-38) where cx = p0af/2 8 = 2(W/b)2/llpae p = sea level air density = relative air density at altitude = p/p0 b = wing span= Equation (3-38) is fundamental to performance analysis. By differentia- tion, the minimum thrust required for steady flight is shown to be T. = 2 ~ (339) and the corresponding velocity is that for the maximum ratio of lift to drag V(L/D) = (8/cx)~'4 . (3-40) max Maximum endurance, te, results from flying at the velocity given by Equation (3-40) and burning all the fuel. These considerations yield te = ~~~!!__ in ( W ) (3-41) cain max f 81 PAGENO="1046" 1040 where y = mf/T is the thrust specific fuel consumption for the particular fuel used, assumed constant throughout the operational range. The remaining items of interest here are the maximum velocity, V and the range, R. Using Equations (3-39) and (3-40), Equation (3-3~ can be solved for.Vm~ in the form V T nT ~2 ,l/2 1/2 max = ~ - 1 . (3-42) (LID) mm L\ mm' -~ The expression for the range follows from multiplying each incre- mental time step by the velocity at that time and integrating over the time needed to burn the fuel. Although the product V(L/D) cannot, in general, be maximized for level flight, the assumption of constant altitude gives results that are generally within about 3 percent of the optimam (Perkins and Hage, 1956). The resulting one-way range in miles is given by 1 855 W 1/2 11/2 1/21 R = T7~ (~) max - (W~ - Wf) j . (3-43) Maximum combat radius, Rm, can be estimated by assuming that the sortie consists of two portions: (1) the outward leg starting with weight Wmax and burning SWf of the available fuel, and (2) the inward leg after expending the armament starting with weight Wmax - ~Wf - Wa and burning (1 - 6)Wf of the available fuel. Since each of these ranges must equal R,~, their expressions as given by Equation (3-43) can be equated and solved for t~, leading to W/4W = 1 - f max (344) 1 + (W /W ) ` 11 + (W /W ) ` g max g max Results The parameters Tmin, VCL/D) t~ ~ R~, and iS are listed in Table 3-15 fOr aircraft with u~~anged maximum takeoff weight and in Table 3-16 for aircraft with unchanged payload weight. These comparisons show that for steady flight performance there is little difference between the constant takeoff weight and constant payload modifications, although significant performance degradation 82 PAGENO="1047" Table 3-15. Performance comparisons for aircraft with unchanged takeoff weight. Aircraft VA V/STOL Parameter Fuel JP-5 CH4 H2 JP-5 CH4 H2 Minimum thrust at Wmax~ Tmin (lbf) 4960 5000 5130 5080 5100 5170 . Velocity at minimum thrust, 248 246 243 222 221 220 V(L/D)max (knots) Endurance, te (hr) 3.30 3.21 2.93 1.60 1.57 1.45 Maximum velocity, Vmax (knots) 601 594 579 641 637 630 Maximum combat radius, R1~ (mi) 570 548 499 245 242 225 Outward fuel fraction at (cS) 0.58 0.57 0.55 0.57 0.57 0.55 PAGENO="1048" Table 3-16. Performance comparisons for aircraft with unchanged payload. Aircraft VA V/STOL Parameter Fuel JP-5 CH4 H2 JP.-5 CH4 H2 Minimum thrust at Wmax~ Tmin (lbf) 4960 5090 5380 5080 5140 5270 Velocity at minimum thrust, V(L/D) (knots) max 248 248 249 222 222 , 222 Endurance, te (hr) 3.30 3.15 2.78 1.60 1.56 1.43 Maximum velocity, Vmax (knots) 601 593 578 641 637 629 Maximum combat radius, Rm (ml) 570 553 496 245 241 223 Outward fuel fraction at (cs) 0.58 0.58 0.56 0.57 0.57 0.55 ~ PAGENO="1049" 1043 results from both synthetic fuels. The VA sensitivity to the increased weight required to carry a constant payload is shown in endurance de- creases compared with the constant maximum weight version. The V/STOL aircraft does not show any performance penalty when the weight is in- creased to permit the carrying of the JP-5 configuration payload, pre- sumably because its ducting and engine require a larger fuselage rela- tive to the fuel volume than does the VA. Thus, the fuselage volume of the VA increases by 18 percent for methane storage and 82 percent for hydrogen storage, whereas the comparable figures for the V/STOL fuselage volume are only 12 and 58 percent. The small steady state performance penalties for the heavier air- craft do not mean that increasing the weight in order to maintain constant payload is without other significant penalties. Increases in weight, fuselage length and diameter, and wing span may be important in naval operations aside from their effect on flight performance. Additionally, the maneuvering performance of these heavier aircraft, not considered in this preliminary analysis, may be degraded by the increased rolling inertia resulting from the larger wings. For steady-flight performance, the variation between fuel types is considerably greater than that between payload capacities for a given aircraft. Thus, endurance suffers a degradation of less than 5 percent in going from JP-5 to methalle, but of more than 10 percent (approaching 15 percent for the VA) in going from JP-5 to hydrogen. Similar pen- alties apply to the maximum combat radius. Maximum velocity, on the other hand, shows a penalty of not more than a few percent. As might be suspected, these performance penalties result largely from the increased skin friction of the larger fuselage. It is pos- sible to show that for either maximum endurance or maximum range flight conditions, the drag is directly proportional to the equivalent fric- tion (or parasite) area, f, and this is borne out in the present calculations. The results presented here are at some variance with estimates for supersonic transports (Whitlow et al, 1966) wherein payload increases are predicted. These optimistic estimates are based on the assumption that the higher specific volumes of the synthetic fuels do not material- ly change the aircraft weight (Chambellan et al, 1967). Although this assumption may be satisfactory for large aircraft with relatively thick delta wings that can accommodate cryogenic fuel tanks, it does not seem satisfactory for the thin high performance wings on military aircraft. In addition, supersonic transports already require insulation to pre- vent overheating and breakdown of hydrocarbon fuels. Excepting this difference in the assumption of fuel storage, however, the analysis techniques used here are similar to those employed in other investiga- tions (Whitlow et al, 1973). 85 PAGENO="1050" 1044 The weight estimates in this analysis are highly preliminary ones based upon dimensional expansion of the fuselage. These estimates may be significantly in error, and the weight effect may be more its- portant than shown here. Consequently, further study of the feasibil- ity of cryogenic fuels for tactical aircraft should include at least a preliminary fuselage and fuel tank design. 86 PAGENO="1051" 1045 SECTION 4 MISSION ANALYSIS AND FUEL COMPARISON INTRODUCTION This section describes how the mission performance of force ele- ments operating on petroleum-based fuel is compared to that of the same force elements modified to operate on synthetic fuel. The over- all approach is summarized here. First, the primary, non-strategic Navy missions and the major war- fare areas which they comprise are related to the force elements selected for investigation. A generalized mission and threat spectrum is used to identify the role of each ship, and some geopolitical trends are introduced. This information provides the rationale for selecting a single, representative mission for each ship from which a mission profile of speed and time at speed is derived. For the sea control ship and attack aircraft carrier, nominal air wings are assumed and sortie rates and mission durations are given for each aircraft. The mission profiles are used to determine the mission fuel requirement for each force element. A measure of effectiveness, the number of ship refuel- ings to complete the mission, is introduced and used to compare the performance of each fuel. MISSION PROFILES Major Navy Missions and Warfare Areas The major, non-strategic Navy missions are: Sea control Projection of power ashore, and Overseas presence. The sea control mission involves the requirement to keep open the sea lines of communication (SLOC) between the U.S. and its allies in the face of enemy threats. Projection of power ashore relates to the means by which U.S. naval power is brought to bear. Examples of this mission include aircraft carrier-based tactical air strikes and the landing of marines by amphibious assault. Overseas presence is the means by which naval forces are used to demonstrate U.S. national purpose and resolve. A common example of this mission is the deploy- ment of an attack carrier task force into some troubled region of the world in which the U.S. has an interest. 87 PAGENO="1052" 1046 Within each broad mission are a number of naval warfare areas of which the major ones are given in Table 4-1 along with their common acronyms. Table 4-2 displays the relationship between the, study force elements and the warfare areas. For the ships, the entries indicate that the ship is generally applicable to the specific warfare area. Of the three types of aircraft shown, the VA and V/STOL are analyzed in some detail as described in Section 3. Fighter aircraft (VF), helicopters, and other aircraft are considered in later discussions of the SCS and CVX. Each aircraft type is applicable to a number of war- fare areas as indicated. In addition, the basing options for each aircraft are represented by the number of entries in the table in con- junction with the basing key. Table 4-2 demonstrates that the force elements chosen for study are indeed applicable to a wide range of Navy missions and warfare areas. Table 4-1. Naval warfare areas. ASMD - Self protection against anti-ship missiles ASW(P) - Force protection against subsurface threats MW - Force attrition of airborne threats ASW(A) - Attrition of subsurface threats ASUW - Warfare against surface ship threats ARW - Strike warfare using carrier-based tactical air EW - Electronic warfare CAC - Command, control, and communications COS - Combat direction systems SURV - Surveillance AMW(L) - Amphibious lift capability NGFS - Naval gunfire support MCM - Mine countermeasures MIW - Mine warfare MLS - Mobile logistic support for sea-based forces SPW - Special warfare 88 PAGENO="1053" 1047 Table 4-2. Force element mission assignments. WARFARE AREA DISPLACEMENT MONOHULLS -- - SPECIAL HULLS AIRCRAFT -- PF,DD SCS LHA CVX PHM,DEH SES VA,VF V/STOL HELO x x x x x x x x x x ASMD ASW(P) MW ASW(A) ASUW ARW EW CAC CDS SURV AMW(L) NGFS MCM MIW MLS SPW x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x 1,4 1,2,4,5 1,2,3,4,5 1,2,5 1,2,3,5 1,4 1,2,4,5 1,4 1,2,4,5 1,2,3,5 1,4 1,2,4,5 1,4 1,2,4,5 1,2,3,4,5 1,4 1,2,4,5 1,2,3,4,5 1,4 1,2,4,5 1,2,3,4,5 4,5 1,2,3,4,5 1,2,3,4,5 1,2,3,4,5 1,4 1,2,4,5 1,2,3,4,5 x x Basing Key: 1. CV 2. SCS 3. Surface combatant 4. Land-based (Marine) 5. LPH-LHA 89 PAGENO="1054" 1048 Basic Approach to Mission Selection While the study force elements are applicable to many missions, it is found that their fuel requirements can be generalized to essentially two broad classes: specialized missions and task force missions. These are characterized on the basis of the following factors. Figure 4-1 shows ship full-load displacement versus the mission and threat for which the ship is generally designed. The upper portion of the chart gives the displacement of the ships considered in the study and that of a CVN for comparison. While the mission and threat indi- cated for each ship is highly qualitative, some general observations can be made. The larger aircraft carriers, the CVX and CVN, are designed to operate in the multidimensional submarine, surface, and air threat environment for extended periods of time. These ships pro- vide a broad range of mission capability such as projection of power via tactical aircraft and establishing control of the seas by virtue of the support ships and aircraft comprising the task force which necessarily accompanies these high value ships. The amphibious assault ship, the LHA, is also a high value ship requiring an accompanying task force for its defense. At the other end of the mission and threat spectrum are the smaller displacement ships, the PHM, DEH, and SES. These ships are generally envisioned as configured for specialized missions or warfare areas such as ASUW, ASW, or AAW, and are generally expected to operate in a limited, single-dimension threat environment as indicated on the chart. The PF and DD, in the 3000 to 6000-ton displacement range, are pri- marily configured for ASW, ASUW, and AAW, and are generally employed as escorts for aircraft carriers to provide close-in defense. These are quite versatile ships, and can also perform numerous independent missions. The SCS at 14,000-tons displacement is a specialized air- craft carrier which does not carry either the number or types of aircraft needed to survive in the threat environment for which the CVX is configured. Consequently, the SCS operates at the lower end of the threat spectrum as shown. Its probable missions include the escort of task forces such as merchant or military convoys, underway replenishment groups (URGs), and amphibious assault forces which, be- cause of the expected threat environment, do not require a CVX or CVN class carrier. It is worth noting that most of the ships chosen for study, ie, the PHM, SES, PF, SCS, and CVX, are a part of the Navy's "low-mix" forces. These ships can purportedly be acquired at low cost relative to "hi- mix" ships, and consequently in greater numbers, to meet Navy commit- ments in many lower risk areas of the world. A few general trends, some of a largely geopolitical nature, which are likely over the next decade and which bear on the derivation of 90 PAGENO="1055" THREAT SPECTRLM Figure 4-1. Ship displacement versus mission and threat. the mission profiles are shown in Table 4-3. Of particular note to this study are: (1) the growing importance of Navy general purpose forces; (2) the reduction in overseas bases which results in longer missions and imposes greater demands on logistics and underway re- plenishinent; and (3) the procurement of less sophisticated, lower-cost platforms. This last item implies that these platforms will be con- ventionally powered in light of the expected, continued high invest- ment cost for nuclear propulsion. 1049 FULL LOAD DISPLACEP~ENT IN THOUSANDS OF TONS PHM,DEH SES PF,DD SCS LHA CVx CVN 90 1TT~T 10 i 20 30 40 50 IIllUIllIllhlllllIflhIIllh!llhIIIIllhIflllllllIllIllhllI IllhIIIlHIIIItIIlllIllIHhIIIHIllhHhIIIllhIIlIIlluIU ~llIhUhIIIllllhIIllhIIII1III 60 70 80 . ~N\~\ N\N~ AAA A A £ A I ~W, ~ ~W * Cv ` ESCORT I ESCORT FOR CONVOY, URG, AMPHIB I I AMPHIB LIFT, ASSAULT I *f MODERATE TAC AIR, SEA CONTROL I SUSTA TAC A SEA COl I [NED IR ITROL III I LOW SUB, OR LIMITED AIR OR SURFACE Iii I MISSION SPECTRUM I I LHA REQUIRES MODERATE OTHER FORCES AIR, SUB, FOR DEFENSE AND SURFACE I I HIGH AIR, SUB, AND SURFACE 91 PAGENO="1056" 1050 Table 4-3. Trends: next decade. Reduction in overseas bases Small wars may continue; less superpower involvement Swing in isolationist direction; Navy least affected Increased dependence on strategic materials from abroad, particularly the Middle East Increased presence in crisis areas Navy general purpose forces of growing importance Navy will receive larger fraction of DOD budget Procurement of larger number of less sophisticated platforms will continue - Investment cost for nuclear ship propulsion will remain high Gas turbine propulsion will increase in popularity Surface effect and hydrofoil technology will improve - Many nations will opt for SSM-capable ships Sumary of Mission Profiles Tables 4-4, 4-5, and 4-6 provide a summary of the significant ship and aircraft mission parameters. The missions are described in greater detail in the following section. Table 4-4 shows the principal characteristics for each mission in- cluding total duration, total range, and a brief description. Table 4-5 gives the operational parameters for each ship which are used to determine total fuel requirements. It should be noted that the mission profiles of speed, time, and range are separated into typical transit day profiles and operating area profiles which apply to each day in transit or in the operating area. The mission thus consists of a transit to the operating area, a period of time spent in the operating area performing some function, and a transit back to base. For the DEH and SES, the entire mission is essentially in the operating area. For the operating area phase of the LHA mission, the ship is assumed to be at anchor and hence the speed and time parameters given for this ship apply only to its transit phase. 92 PAGENO="1057" Table 4-4. Principal mission characteristics. 0 SHIP MISSION DURATION (Days) RANGE (NM) MISSION DESCRIPTION PHM SEA CONTROL SSM Engagement 1.35 . 1.255 High speed transit to operating area. Six- hour SSM engagement. Return to base at near max lift/drag speeds. Mission foilborne. DEH SEA CONTROL Defense of protected convoy lane 7.2 5,200 Sweep of 2600 nm protected lane both ways using sprint and draft tactic for submarine search. Sprint @ 45 knots. SES SEA CONTROL Defense of protected convoy lane 4.6 5,200 Same as DEH mission but sprint @ 70 knots. PF SEA CONTROL Task force defense . 24.4 12,000 Escort of task force to/from op area. Five days patrol in op area. Divert twice/day' in transit for sub DO SEA CONTROL Task force defense 24.0 * 12,000 contacts. Same as PF mission but higher divert speed for sub contact. SCS . SEA CONTROL Task force defense 24.6 12,100 Task force escort to/from op area. Five days in op area. Continuous VSTOL and ASW helo stations maintained in transit and in op LHA PROJECTION Amphibious lift 25.5 ~ 10,000 . area. . Transit to/from amphibious objective area. Five days in op area. 20-kt speed of advance. CVX . SEA CONTROL Multi-threat engage- ment PROJECTION Tactical air strikes 24.2 12,100 Transit to/from op area using aircraft in sea control role. Five days in op area conducting tactical air strikes. PAGENO="1058" Table 4-5. Ship operational parameters. :* c.T' to SHIP DAYS I TRANSIT DAY PROFILE IN TRANSIT ~ ~ 1~W DAYS IN OP AREA OP AREA DAY i~i~i vi~~~r -~~i~r SPE~~ 1~i~s V~tT 16.7 30 50 150 PHM 1.1 10 16.7 50 30 500 500 0.25 3 8* 35 0 105 0 3 13 35 50 DEH - - - - 7.2 16 45 720 0 115.4 45 SES - - - - 4.6 8* 16 0 70 16 1120 320 74.2 100 70 16 PF 19.4 20 4 20 29 400 116 5 20 4 20 80 320 408 78 100 20 29 16 DD 19.0 20 4 20 32 400 128 5 20 4 20 16 20 16 80 320 398 76 100 20 32 16 SCS 19.6 16 8 20 24 320 192 4 24 96 312 176 451 20 24 20 LHA 20.5 22 2 20 24 440 48 5 - - 16 - 320 41 100 24 16 CVX 19.2 16 8 20 25 320 200 5 20 4 25 100 308 174 20 25 *Corresponds to 20 mm/hr of drift and 40 mm/hr of sprint PAGENO="1059" Table 4-6. SCS and CVX aircraft utilization. CA~ Ship Aircraft Type Number of Embarked Aircraft Sorties per Aircraft-Day Hours per Sortie Number of Aircraft Flying per Day Transit Op Area SCS VSTOL 10 2.0 1.44 - 4.0 9 . 9 Helo ASW 10 - 2.0 6 3 CVX * Fighter 12 1.5 3.0 12 6 Attack 12 2.3 2.9 4 12 Fixed wing ASW 12 1.5 5.0 12 4 Helo ASW 8 2.0 4.0 6 3 Early Warning 4 1.5 6.0 3 3 Electronic Warfare 2 1.5 2.5 1 1 Reconn 2 1.5 2.5 1 1 Helo Rescue 4 2.0 3.0 2 2 Tanker 4 - - - - ~0 c-n PAGENO="1060" 1054 Table 4-6 shows the numbers and types of aircraft embarked on the SCS and CVX and their utilization during the transit and operating area phases of the missions for these two ships. Rationale for Selected Force Elements PATROL HYDROFOIL MISSILE (PHM). The PHM is a hydrofoil of 231 tons displacement which is modeled in the study closely after the PHM now under construction. This ship is a high-speed platform designed to operate in coastal waters or in narrow, restricted seas. Its small size and therefore low fuel capacity greatly restrict its use for ex- tended open ocean missions. The ship will possess an anti-surface ship capability (ASUW) by virtue of its surface-to-surface missile* system. Depending on its weapon and sensor suite, possible PHM mis- sions include shadowing or trailing of surface combatants, maintaining a barrier station against transiting surface ships or submarines, SSM engagements in coastal waters, forward picket ship air defense for a task force, and riverine warfare. The mission profile devised for the PHM is a sea control mission involving a SSM engagement a relatively short distance from a base. The profile consists of a high-speed transit of 500 nm at 50 knots to an operating area in which there is a 6-hour SSM engagement. During this missile exchange the PHM is assumed to operate for 3 hours at 35 knots and 3 hours at 50 knots. Return to base is again at a distance of 500 am and at a speed of 30 knots which is near the speed of max- imum lift-to-drag and therefore the most economical speed regarding fuel consumption. This mission requires 1.35 days and covers 1255 tim. The entire mission is conducted with the ship foilborne. DESTROYER ESCORT HYDROFOIL (DEH). The destroyer escort hydrofoil is included as an example of a larger (1363 ton) open-ocean hydrofoil; the ship modeled corresponds closely to one proposed by Aroner and Hubbard (1974). This ship has many of the same missions as conven- tional destroyer escorts such as task force defense, ASW, air defense, gun fire support, etc, but would provide significant added performance by virtue of its higher speed in the foilborne mode over that of con- ventional escorts. The mission profile for the DEH represents a sea control mission involving the defense of a protected convoy lane; the lane is period- ically swept by a variety of platforms searching primarily for sub- marines. For this mission, a force of DEHs is assumed to sweep the lane using a sprint and drift tactic in which the ship drifts for 20 minutes of each hour using its sonar to listen for submarines which may have penetrated the lane. The DEH then sprints for 40 minutes at 45 knots to a new search location, resulting in an effective speed of advance (SOA) of 30 nm/hr. The spacing and operation of the ships in 96 PAGENO="1061" 1055 the DEH force are such that the high level of acoustical noise gen- erated during the sprint phase does not significantly degrade the sonars of other ships which may be drifting and listening. The lane is 2600 mm long and is swept both ways. The entire mis- sion requires 7.2 days and covers 5200 nrn. SURFACE EFFECT SHIP (SES). The surface effect ship is modeled closely after the 2200-ton SES now in advanced development. This ship could have many missions similar to the PHM and DEH but with added performance by virtue of a maximum speed approaching 100 knots. The same mission profile used for the DEH is used for the SES ex- cept that the sprint speed is 70 knots instead of 45 knots. The total mission range is 5200 mm but the mission time is reduced to 4.6 days as the effective speed of advance is 46.7 nm/hr. PATROL FRIGATE (PF). The patrol frigate analyzed in the study is a 3000-ton ship modeled after the 3400-ton PF now under construction. One of the prime missions for this ship is that of escort for task forces which do not have an attack aircraft carrier such as underway replenishment groups, amphibious assault task forces, and merchant and military convoys. These groups of ships may be defended by the sea control ship, and the PF could serve as escort for this ship. In this role the PP would be utilized primarily for ASW. The mission profile for the PF represents task force defense in a sea control mission in which the PF provides escort for an amphibious assault force defended by sea control ships. The mission consists of a transit phase of 5000 mm to the operating area, 5 days on patrol in the operating area, and return to base. The daily mission profile in transit and in the operating area is given in Table 4-4. During tran- sit most of the time is spent at 20 knots, the approximate SOA of the LHA in the force. It is assumed that the PF diverts twice per day at high speed to investigate submarine contacts. In the operating area, the PF maintains patrol and watching for 5 days operating 20 hrs/day at 16 knots and 4 hrs/day at 20 knots. The mission lasts for 24.4 days during which the ship covers 12,000 mm. A mission range of about 12,000 nm was chosen for the PF as well as for the DD, SCS, LHA, and CVX for several reasons. First, this long mission will tax the logistics pipeline required to support ships op- erating at great distances from their bases and thus highlight the differences among the resupply concepts to be analyzed in subsequent work. Secondly, the requirement to operate at great distances from base assumes that the U.S. Navy cannot depend in the future on base rights or fuel availability in forward areas, necessitating long missions. 97 PAGENO="1062" 1056 DESTROYER (DO). The 6000-ton destroyer analyzed in the study is modeled after the DD-963 now under construction but is of somewhat smaller displacement. The DD is a multi-purpose combatant. One of its prime functions is as an escort for an attack carrier task force. Depending upon its combat weapon suite it can be used for ASW, air defense, antisurface ship warfare, or gunfire support. For the role considered here, it is used in a task force defense mission. The mission profile for the DD is identical to that of the PF except that the submarine contact divert speed is assumed to be 32 knots instead of 29 knots. The mission lasts 23.9 days and covers 12,000 nm with 5 days spent on patrol in the operating area. SEA CONTROL SHIP (SCS). The sea control ship analyzed in the study is a 14,000-ton ship modeled after the current design for this proposed ship. It is a major component of the Navy's "10-mix" forces to be used in threat areas and for missions which would not justify the use of an attack aircraft carrier. The mission profile for the SCS represents task force defense in a sea control role with transit to an operating area, followed by 5 days in the operating area and transit back to base. The daily profile in. transit assumes 16 hr/day at 20 knots and 8 hr/day at 24 knots, the latter speed and time corresponding to a higher speed required for aircraft operations. During the operating area phase, the SCS operates 20 hr/day at 16 knots and 4 hr/day at 24 knots. The SCS is configured to carry about 21 helicopters and V/STOL air- craft, the exact mix depending on the SCS mission and expected threat. The helicopters are used primarily in an ASW role, and the V/STOL in AAW or ASW roles and for surveillance. As an ASW aircraft, the V/STOL would be configured to lay sonobuoy fields and to attack surfaced submarines. For the mission envisioned here, the SCS is assumed to carry 10 V/STOL aircraft and 10 ASW helicopters as shown in Table 4-5; the V/STOL is patterened after the AV-8A discussed in Section 3 and the helicopter after the SH-3H. Table 4-5 also gives representative values for the number of sorties per day and the length of each sortie. These values determine the number of aircraft required to maintain at least one aircraft continuously on station. The last two columns of Table 4-5 give the number of each type of aircraft flying per day during both the transit phase and the operating area phase of the mission. During both phases, nine V/STOL aircraft are required per day to main- tain a continuous combat air patrol (CAP). During transit, it is assumed that two ASW helicopter stations are continuously maintained requiring six helicopters flying per day. During the operating area phase, with an assumed reduced submarine threat, only one helicopter station is maintained requiring three helicopters operating per day. 98 PAGENO="1063" 1057 AMPHIBIOUS ASSAULT SHIP (LHA). The amphibious assault ship is modeled after the LHAs now under construction. The primary mission of these ships is amphibious lift of troops and assault materiel and to provide command and control of the entire assault operation. The mission profile for this ship assumes a transit of 5000 mm to an operating area with five days spent in the operating area followed by a return transit. Only fuel utilization for ship propulsion during the transit phase is treated. In transit the ship is assumed to spend 22 hr/day at 20 knots and 2 hr/day at 24 knots, the latter period rep- resenting possible diversionary action to avoid submarines. Defensive forces including an SCS and various numbers of PFs and DDs are assumed to be operating along with the LHA. The mission covers 10,000 ma and requires 25.5 days with 10.5 days spent in transit each way. ATTACK AIRCRAFT CARRIER (CVX). The CVX has been proposed by the Navy as a possible follow-on to the Nimitz class CVNs. It would be about half as large as a CVN, 55,000 tons versus 90,000 tons, and could be either conventionally or nuclear powered. It would carry about 60 high performance aircraft, and would be used in high threat areas of the world. The CVX model used in the study has a displacement of 55,000 tons, and its other dimensions such as length, beam-to-draft ratio, etc, are patterened after the Midway-class aircraft carriers. The CV type aircraft carrier exhibits flexibility in its possible missions in that the aircraft complement can be adjusted for both mis- sion and threat. For a force projection mission, the aircraft wing could be more heavily weighted with attack than with fighter or ASW aircraft. For a sea control mission where both air threat and sub- marine threats predominate, the opposite mix would apply. For a show of force (presence), a balanced mix of attack, fighter, and ASW air- craft might be appropriate. Clearly, any CVX mission will require multiple aircraft types with different performance and fuel requirements. While the scope of the study has not permitted the time to analyze the use of synthetic fuels in these many types of aircraft, the results obtained for the V/STOL and the VA aircraft in Section 3 permit preliminary estimates of the fuel requirements for a nominal CVX air wing. The aircraft complement selected for the CVX is given in Table 4-5 with values for sortie rates and sortie mission times. The aircraft represented generally correspond to existing aircraft as follows: fighter, F-l4A; attack, A-7E; fixed wing ASW, S-3A; helicopter ASW, SH-3H; early warning, E-2C; electronic warfare, EA-6B; reconnaissance, RA-5C; rescue helicopter, UH-2; tankers KA-6D. The sortie rates and sortie mission times determine the number of aircraft required to 99 PAGENO="1064" 1058 maintain a continuous airborne station during both the transit and operating area phases of the mission. These aircraft requirements are given in Table 4-5. During the transit phase of the mission, more ASW aircraft and interceptors are flown reflecting the greater emphasis on an asswned submarine or air threat. Some attack aircraft are flown to complement the interceptors which would be maintaining CAP stations and possibly to attack surface targets. Thus, during the transit phase, the air- craft are utilized in a sea control role. During the operating area phase of the mission, the emphasis is on force projection. Greater numbers of attack sorties are flown, and fewer ASW and AAW sorties are required. On the return transit, the aircraft return to the sea control role. While tanker aircraft are embarked, no in-flight refueling is assumed. Regarding the operation of the ship itself, the mission profile is almost identical to that for the PF, DD, SCS, and LHA, involving a transit of 5000 us, 5 days of operations in the objective area, and a return transit. During transit, 16 hr/day is at 20 knots and 8 hr/day at 25 knots, the latter period corresponding to the higher speed re- quired for aircraft operations. In the objective area 20 hr/day are at 16 knots and 4 hr/day at 25 knots. The return transit is at the same utilization as the outward leg. Total mission time is 24.2 days and total range is 12,100 mm. COMPARISON OF FUELS Measure of Fuel Effectivenss A measure of effectiveness tentatively selected for the overall study is the fraction of the mission time during which the force ele- ment is in a tactically useful military posture. This is taken to be the mission time less the time spent in refueling divided by the mis- sion time, T -NT f = (4-1) where £ = fraction of mission time, Tm, the force element is in a tactically useful military posture N = number of times the force element must be refueled during r the mission Tr = total time spent in refueling 100 PAGENO="1065" 1059 The product Nr Tr represents the mission "downtime" for refueling and depends primarily upon the fuel consumption rate, ie, the mission profile, and the refueling strategy. Some possible refueling strat- egies include the following: operation of a tanker in close proximity to the force element throughout the mission; withdrawal of the force element to a tanker in a rear area; or ferrying fuel from a tanker in a rear area to the forward deployed force element. In this study, the emphasis is on determining the fuel requirements for each force element for representative mission, ie, Nr, and this quantity is the measure of fuel effectiveness employed. Future work will integrate the force elements into task forces, examine alterna- tive refueling strategies, and determine the time-on-station factor, £ , for the task force using various fuels. Methodology SURFACE COMBATANTS. Section 3 described how each ship is modified for the various synthetic fuels; the modifications result in a ship with different dimensions and fuel capacity, but with the same dis- placement. The following approach is used to determine the mission fuel requirements and the number of refuelings to complete the mission. Using the mission profiles of Table 4-5, the propulsive power require- ments and fuel consumption rates are determined at each speed. Combin- ing this with the time spent at each speed, also given in Table 4-5, the amount of fuel used by the ship over the entire mission is cal- culated. With the given fuel capacity for each ship, the fuel requirement determines the number of fuel loads needed to complete the mission. A 10 percent fuel reserve is assumed for each ship. If the initial loading is insufficient, the number of refuelings required to complete the mission is the number of additional fuel loads beyond the initial load rounded to the next higher integer. For example, if the total mission requirement is 6.3 fuel loads, then 6 refuelings are required over the mission; this is the minimum number of times the ship would have to rendezvous with a fuel supply ship. AIRCRAFT CARRIERS. For the SCS and CVX, the amount of fuel used by the aircraft during the mission is added to the ship propulsion re- quirement. In addition, fuel stored on the CVX for use by its excort ships is taken into account. Section 3 describes a calculation which compares the performance of V/STOL and VA aircraft modified to operate on liquid hydrogen or liquid methane with aircraft using JP-5. The results indicate that for non- accelerated flight, the aircraft can be enlarged sufficiently to carry the lighter fuel, but the increased drag leads to approximately a 10 per- cent degradation in endurance for hydrogen and a 5 percent degradation when using methane. The modified aircraft have unchanged takeoff weight 101 PAGENO="1066" 1060 and carry a fuel load of energy content equivalent to that of the JP-5 aircraft. The conventional fuel (JP-5) requirement for the aircraft on the SCS and CVX is determined by the sortie rates and times of Tables 4-5 and 4-6, the fuel capacity of each aircraft, and the assumption that the aircraft uses all of its fuel on each sortie except for a 10 per- cent reserve. Since the synthetically fueled aircraft discussed in Section 3 are modified on the basis of constant stored energy content, the JP-5 requirement can be transformed to a hydrogen or methane re- quirement by a factor reflecting the relative heating values and the nominal performance degradation of the two synthetic fuels. The deg- radation factor of 10 percent on hydrogen and 5 percent on methane is assumed to apply consistently to all aircraft types. The aircraft fuel requirement is then added to the fuel requirement for ship pro- pulsion for the SCS and CVX. The aircraft fuel requirements introduce an additional factor in choosing the design parameters for the SCS and CVX, that of the initial weight of fuel. For the SCS, the fuel weight must reflect both ship propulsion and aircraft requirements; for the CVX, it must reflect the requirement for ship propulsion, aircraft use, and fuel for escort ships. Using the LPH-9 as a model for the SCS, as this ship was the interim SCS, it is found that this ship carries about twice as much fuel for ship propulsion as for aircraft use. Thus, instead of 1350 tons of DFM as the baseline SCS fuel weight, 2000 tons of DFM and .JP-5 is used to account for aircraft requirements. To determine the baseline fuel load for the CVX, CVA-67 provides the model. For this ship, the stored fuel proportions are about 50 percent for aircraft use and 50 percent for ship propulsion and escort use. With a baseline DFM fuel weight of 3650 tons, an additional half of this is allocated for escort use, and the total amount approximately doubled to account for aircraft fuel requirements. Consequently, 10,000 tons of DFM and JP-5 is used as the CVX baseline fuel requirement when aircraft fuel requirements are considered. While only methane and hydrogen are considered as alternate fuels for aircraft use, the fuel requirements for SCS and CVX propulsion only, using all of the synthetic fuels, are included. In this case, the lower baseline DFM fuel weight is used, 1350 tons for the SCS and 3650 tons for the CVX. Mission-Dependent Fuel Requirements The mission fuel requirements are given in Table 4-7. The entries are the total number of ship fuel loads, including the initial one, to 102 PAGENO="1067" Table 4-7. Number of ship fuel loads required to complete mission. ~~hip PHM DEH SES PF DD SCS Ship only SCS + Aircraft LHA CVX Ship only. CVX Aircraft DFM 1.3 2.3 1.4 3.6 3.2 1.1 1.6 1.1 1.2 1.3 H2 0.9 1.6 1.1 3.4 3.2 1.3 1.9 1.1 1.4 1.7 NH3/L 3.0 5.5 3.3 8.9 7.9 2.9 2.6 2.9 NH3/H 3.1 5.7 3.4 9.1 8.1 2.9 2.7 3.0 N2H4 3.2 5.7 3.5 9.0 7.9 2.8 2.7 2.9 CH4/L 1.2 2.2 1.3 3.6 3.3 1.2 1.7 1.1 1.2 1.4 CH4/H 1.3 2.3 1.4 4.0 3.7 1.3 1.9 1.2 1.4 1.6 CH3OH 2.7 4.9 2.9 7.6 6.8 2.5 2.3 2.5 MMA 1.6 2.9 1.7 4.6 4.2 1.5 1.4 1.5 (A) PAGENO="1068" 1062 complete the mission. Table 4-8 gives the number of ship refuelings required to complete the mission. As indicated earlier, this is the minimum number of times the ship would have to visit or be. visited by a fuel supply ship, and it implies that a refueling ship is in imme- diate proximity to the ship. If the tactical situation demanded that the force element withdraw to a rear area to refuel, then additional fuel would be required for the transit to and from this area and a larger number of refuelings would be required to complete the mission. DYNAMIC LIFT SHIPS. The mission fuel requirements for all of the dynamic lift ships are discussed together as there are no significant differences among them concerning their utilization of synthetic fuels. For the PHM mission profile and the modification strategy used it is seen (Table 4-7) that the PHM operating on hydrogen, diesel fuel, methane, or mixed methylainines can about complete the mission on the initial fuel load. However, the hydrogen-fueled ship does have a greater range than the other three ships. For a PHM using methanol, ammonia, or hydrazine, one or two refuel- ings, at least, are required to complete the mission (Table 4-8). Refueling on a high speed, short duration mission could significantly hinder its completion, particularly if it is necessary to withdraw to a rear area for refueling. The ability to complete the mission without refueling is of tactical advantage and importance for this particular ship. Even this mission of 1.4 days would likely be considered ex- tremely long for a ship of this size due to crew fatigue and habit- ability constraints. A reduction in mission time by one-half would still allow the PHM fueled on hydrogen, diesel fuel, methane, and methylamines to complete the mission on the initial load, but would still require another refueling for the remaining three fuels. It should be noted that the fuel requirements for the PEN and all of the other ships are, of course, a function of the mission profile. A profile could be constructed in which the P1-N mission could be com- pleted with the initial load of fuel regardless of the fuel. For this case the PHM fueled on hydrogen, diesel fuel marine, methane, or methylamines would simply possess an added performance capability which was not being utilized. The remarks made for the PEN apply in most part to the DEH and SES. These are much larger ships and are designed for longer, open ocean missions in contrast to the limited range PHM. The fuel requirements for these two ships are shown in Tables 4-7 and 4-8. Their missions are identical except for the higher sprint speed of the SES. It is seen that the fuels fall into roughly two classes as for the P1114: the ships fueled on hydrogen, diesel fuel, methane, and methylamines have comparable range performance; the ships fueled on methanol, anunonia, and hydrazine require approximately twice as much fuel as the ships of 104 PAGENO="1069" Table 4-8. Number of ship refuelings required to complete mission. Fuel PHM DEH SES PF YD Sc s SCS+ LHA cv cvx+ DFM 1 2 1 3 3 Ship 1 only Aircraft 1 1 Ship only 1 Aircraft 1 H2 0 1 1 3 3 1 1 1 1 1 NH3/L 2 5 2 8 7 2 2 2 NH3/H 3 5 3 9 8 2 2 2 N2H4 3 5 3 8 7 2 2 2 CH4/L 1 2 1 3 3 1 1 1 1 1 CH4/H 1 2 1 3 3 1 1 1 1 1 cH3oH 2 4 2 7 6 2 2 2 MMA 1 2 1 4 4 1 1 1 c-n PAGENO="1070" 1064 the first class to complete the mission. This may not be a tactical disadvantage on this longer mission unless a long transit is required to rendezvous with a tanker which could occur if one was not preposi- tioned or was much slower than the DEll or SES. DISPLACEMENT SHIPS. The mission fuel requirements for the PF, DD, SCS, LEA, and cVX are also shown in Tables 4-7 and 4-8. These ships are discussed as a group since they depend on the same hull structure model. Consequently, the fuel consumption results and fuel ranking are essentially the same among the ships, allowing for the greater fuel capacity of the larger ships. The results for the displacement ships are similar to those for the dynamic lift ships in that the fuels fall into two classes; the ships designed to operate on methanol, am- monia, and hydrazine require about twice as many refuelings to complete the mission as the ships operating on hydrogen, diesel fuel, methane, and methylamines. The missions for the PF and DD are quite similar except for a slightly greater speed for part of the DD profile. PFs and DDs oper- ating on hydrogen, diesel fuel, methane, or methylamines would have to refuel every six to eight days, whereas on methanol, ammonia, or hydra- zine, refueling would have to occur about every three days. Table 4-7 shows that the hydrogen-fueled PF has greater range per- formance than the DFM-fueled version. This is attributable to the resistance characteristics of the Series 64, sleek-lined hullform assumed for this ship. In the case of small ships like the PF at nor- mal cruising speed or faster, the speed-length ratio is such that wave-making or residual resistance is the major component of drag. Consequently, increasing the length of the ship reduces the powering requirement at the higher speeds. Since the hydrogen-fueled ship is somewhat longer than its conventionally fueled counterpart, the smaller power needed results in slightly greater range even though the latter ship has more stored fuel energy. For the DD, the hydrogen-fueled ship is in a speed_length-powering regime such that this effect is not ob- served and the ranges are equal. For the SCS, LEA, and CVX, these effects are essentially reversed. These are larger hulls, modeled by Taylor series hullforms. Unlike the Series 64 hulls which are residual or wave-making resistance dominated, the Taylor hulls are frictional resistance dominated in the cruise speed range, and increasing the length of these hulls results in increased powering requirements. Another factor is that the structural weight of displacement hulls does not permit much increase in hull volume at constant displacement. As a result the DFM-fueled ships generally contain more stored fuel energy than the hydrogen-fueled versions. The lesser energy content and greater powering requirement for the hydrogen-fueled SCS, LIlA, and CVX results in shorter ranges 106 PAGENO="1071" 1065 than shown by the DFM-fueled ships. Consequently, more fuel is re- quired to complete the mission as shown in Table 4-7. An exception to the above is the LHA where, while the DFM-fueled LilA stores slightly more Btu's of fuel energy than the hydrogen- fueled LilA, the speed-length ratio of the ship is such that slightly less power is required for the longer hydrogen-fueled LilA than for the shorter DFM-fueled LilA. For this particular case the residual resist- ance decreases more than the frictional resistance increases in going from a shorter to a longer ship. Just the opposite occurs for the SCS and CVX. As a result of this effect the fuel requirements of the LHA operating on either hydrogen or DFM are equal. SUMMARY OF RESULTS Ships and aircraft configured to operate on synthetic fuels require an increase in volume and special storage in the case of cryogenic and pressurized fuels in order to store sufficient fuel to achieve perform- ance comparable to that of its petroleum-based fuel counterpart. The required volume increase is greatest for hydrogen and methane and min- imal for the remaining fuels. For ships, the modification strategy which led to the increased volume was one in which all ships dimensions were increased to some extent and at the same time retaining all of the essential features of the DFM-fueled ship. For the aircraft considered, the fuselage was enlarged to store either hydrogen or methane and still retain unchanged maximum takeoff weight. When the performance of the ships and aircraft using the various fuels was compared in the context of representative missions, the following results were found: * Ships modified to operate on hydrogen, methane, or methylamine achieve approximately twice the range of the same ships modified to operate on methanol, ammonia, or hydrazine and consequent1y~ would have to be refueled only half as often. * Ships modified to operate on hydrogen, methane, or methylamines achieve ranges comparable to those of the same ships operating on diesel fuel marine. * The dynamic lift ships, the PHM, DEH, and SES achieve a greater range performance when using hydrogen than for DFM or any of the other synthetic fuels. * For surface combatants in the 3000 to 6000-ton class, the PF and DD, the ships modified to operate on hydrogen and methane achieve approximately the same range performance as that of the DFM- fueled ship. 107 PAGENO="1072" 1066 * For the 14,000-ton SCS and 55,000-ton CVX greater range perform- ance is achieved for the DFM-fueled and methane-fueled ship than for the hydrogen-fueled ship. * For the 40,000-ton LHA range performance is approximately the same for the ship operating on either hydrogen, DFM, or methane. * Carrier-based aircraft modified to operate on hydrogen and methane, and assuming nonaccelerated flight, would be expected to suffer approximately a 10 percent range degradation for hydrogen and a 5 percent degradation for methane. 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"Series 64 Resistance ExperIments on High-Speed Displace- ment Forms," Marine Technology, July 1965. 113 PAGENO="1078" 1072 SECURITY CL.AZSIFICATION OF THIS PAGE (Wkw DMa £or.li BC~1SBT RI~~iI ~ ~i~i~i ~Ag~E READ INSTRUCTIONS BEFORE_COMPLETING FORM ,FWJ.onT ~ 2. GOVT ACCESSION NC GE74TMP-46 ~9DJ5.c7t7/ fall 2. RECIPIENTS CATALOG NUMIER 4. TITLE (~4 4clcelII,) ALTERNATIVE, SYNThETICALLY FUELED, NAVY SYSTEMS: Force Element Missions and Technology S. TYPE OF REPORT I PERIOD COVERED Final Technical Report 16 April 1974-12 Nov. 1974 I. PERFORMING ORG. REPORT NUMBER 7. auTHorwa) B. Berkowitz L. Haun J. DeVore W. McNamara S. Harris N. Slager d. CONTRACT OR GRANT NUMSE~I) N00600-74-C-0744 ~ l~. PEflFOI~5UG ORGAISIZAT1ON NASIE AND ADDRESS TEMPO-Center for Advanced Studies General Electric Co. P.O. Drawer QQ, Santa Barbara, CA 93102 ID. PROGRAM ELEMENT. PROJECT. TABS AREASBORIC UNIT NUMBERS 11. Cor4TC~LLIRG OFFICE IIAHE Sf40 ADDTIESS Advanced Research Projects Agency 1400 Wilson Blvd. Arlington, VA 22209 12. REPORT DATE 12 November 1974 I). NUMBEROFPAGES 113 t& t7OaITOfSIflG AGEtICY lIAblE 6 ADDRESS(I( diflc,.ct Icoo~ Co~~IcolIIng Of fico) Naval Ship Research and Development Center Annapolis Laboratory Annapolis MD 21402 IS. SECURITY CLASS. (of 1kb lOPOOl) UNCLASSIFIED . DECLASSIFICATION/DOWNGRADING SCHEDULE IC. cISTR1DUTIOII STATEI3ENT (of 151. Rp,fl) Distribution limited to U.S. Government Agencies only; Test and Evaluation (12 November 1974). Other requests for this document must be referred to Advanced Research Projects Agency, 1400 Wilson Blvd., Arlington, VA 22209 17. OIZTmOUT1OC STATEIIEIIT (,f ISo ob.tcocl .ctc,od In Block 20. If dIfIo,.nI ho., R.po,l) IC. zupl'LcuEnTAr.Y COTES ID. f(EYOonDZ(cocbI~,.-, cococaooitfi if cocoa .~y ~d I~*nIIfy I,. block c.~kcI Synthetic fuel Methane Navy mission analysis Ship propulsion Hydrogen Methanol Hydrofoils Carrier aircraft Ammonia Methylamines Surface effect ships Gas turbine Hydrazine Displacement ships CO. ~ ,.... -.., ~.. .. .. ~ ~d Ido.I:fy by block ,c.~b.,j This study investigates the potential utility of substances that can be manufactured at sea or in transportable factory complexes and used as gas turbine fuels for the propulsion of a variety of Navy ships and aircraft. Versions of these Navy force elements, appropriately modified to carry each of the fuels, are evaluated and compared on the basis of the number of refuelings required to ac- complish representative missions. Hydrogen, ammonia, hydrazine, methane, methanol, and the methylamines comprise the fuels examined. Their properties, methods of production, manufacturing energy !L~7~ cotrto~ or I ~QV 03 IS OEZOLETE SECURITY PAGENO="1079" 1073 UNCLASSIFThD SECURITY CL*UIYICATION O~ THIS PAOE(~~ D~. ~ requirements, storage requirements as ship fuel, and combustion characteristics are described. The force elements consist bftS4o~sizes~Qf'hydrofoil ships, a surface effect ship, five displacement ships ranging from 3,000 to 55,000 tons, and two types of carrier-based aircraft. Models relating the static (structural weight and volume) and dynamic (size, propulsive power, speed) properties of each vehicle type permit comparison of the mobility performance of the baseline, conventionally fueled force elements and the alternative, synthetically fueled configurations. Using as a criterion the minimum number of refuelings necessary for mission completion, it is found that liquid hydrogen- and liquid methane-fueled force elements are roughly equivalent or superior to their conventionally fueled counter- parts. These fuels, used in modified ships and aircraft, are considered to be compatible with Navy mission requirements. The largest mission performance im- provements are observed in the case of liquid hydrogen-fueled, dynamic lift ships. UNCLASSIFIED SECURITY CLAUIYIC&T&CH 01' Tm~ PACCf~c~ L)mo Cw~~) PAGENO="1080" 1074 TP 360 75-106 SP THE HYDROGEN ECONOMY GEORGE N. CHATHAM Specialist in Aeronautics and Space and Migdon R. Segal Analyst in Science and Technology Science Policy Research Division March 20, 1975 PAGENO="1081" 1075 TABLE OF CONTENTS Page Description of the `hydrogen economy" 1 A. The "hydrogen economy" - - a summary 1 B. The "hydrogen economy" concept 2 1. Generation of hydrogen 3 2. Transportation and storage of hydrogen 4 3. Ultimate use of hydrogen 5 C. The "hydrogen economy" - - underlying assumptions 6 1. Timing 6 2. Technical aspects 6 3. Economics of supply 7 U. The nature of hydrogen 7 1. Properties 7 2. History 8 3. Sources of hydrogen 8 4. Uses of hydrogen 9 5. Unique problems associated with hydrogen 9 E. Hydrogen research today 11 1. NASA automobile engine project 11 2. AEC metal hydride project 12 3. Hydrogen as an aviation fuel 12 4. Federally sponsored hydrogen research today - - spending levels 14 5. Expert opinions on projected future spending levels for hydrogen research 14 II. Feasibility of the "hydrogen economy" 16 A. Hydrogen compared with electricity 16 B. The "hydrogen economy" -- critical questions 17 1. Timing 17 2. Costs 18 C. Forecast 20 1. Vehicular use 20 2. Stationary uses of hydrogen power 23 III. Conclusions 25 IV. Bibliography 28 PAGENO="1082" 1076 I. DESCRIPTION OF THE "HYDROGEN ECONOMY' A. The `Hydrogen Economy" - - A Summary The "hydrogen economy" is a concept which would represent a com- plete revolution in our energy system. Under this concept, hydrogen would be produced from water, using nuclear or solar energy to disso- ciate the water molecule into hydrogen and oxygen. The hydrogen would then be distributed through pipelines and used to replace conventional fuels in a variety of applications, such as transportation, industry, home heating and cooling and electrical power generation. Hydrogen used as described here i~ perhaps better described as an energy storage and transportation system than as an energy source. Ac- cording to the laws of thermodynamics, the process described above must produce a net loss of energy, and that net loss is increased when the energy cost of transporting the hydrogen is taken into account. So hydrogen is riot, as it is sometimes described, a "limitless source of energy". It is a method for storing and distributing energy which is generated by other means. In this sense it is a competitor to electri- city as a method of long-range power distribution. The "hydrogen economy" concept has a number of inherent difficulties which make it unlikely that the system will be fully adapted for use in the foreseeable future. These include the problems of handling and storing hydrogen, the energy inefficiency of using electricity to make hydrogen which is then used to make electricity, the practical impossibility, due to materials, size, and weight handicaps, of ever using hydrogen to fuel motor vehicles, and the likelihood that the exhaustion of our fossil fuel PAGENO="1083" 1077 CRS - 2 supplies will not occur for hundreds of years to come - - by which time more attractive alternatives than hydrogen will very possibly have emerged. These drawbacks to the `hydrogen economy" idea will be dis- cussed in more detail in the following sections of this report. B. The "Hydrogen Economy" Concept In the hydrogen economy, water would be separated into hydrogen and oxygen, with the energy for this process probably being supplied by a virtually non-depletable source such as nuclear or solar energy. The hydrogen produced in this manner would then be transported through pipe- lines, stored until needed, and then burned (recombined with oxygen) to provide fuel for all the needs of our economy, e. g. transportation, industry, fuel for homes, and so forth. The "hydrogen economy" thus can be visualized as a huge closed sys- tern where (a) water is separated into hydrogen and oxygen, with an expen- diture of energy being required, and (b) hydrogen and oxygen are recom- bined to form water, with a release of useful energy taking place. Ac- cording to the laws of thermodynamics, a system of this nature cannot produce a net increase in energy, and in fact must produce a net energy loss. This means that the cost (in energy) of producing hydrogen will be more than the energy output of burning that same hydrogen. Thus hydrogen cannot be considered to be an energy source. Rather, it repre- sents a medium for the storage and distribution of energy which is generated by other means. In this way it is similar to electricity, which is our present method of distributing large amounts of power. The cycle which makes up the hydrogen economy consists of three phases: (1) generation of hydrogen from water, (2) transportation and PAGENO="1084" 1078 CRS - 3 storage of hydrogen, (3) combustion of hydrogen to produce energy. These will be considered separately in the following sections. 1. Generation of Hydrogen. Hydrogen today is obtained from hydro- carbon fuels as a byproduct of the petrochemical industry. However, since one of the main purposes of the hydrogen economy is to reduce our dependency on fossil fuels, it is presumed that hydrogen for the hydrogen economy will be obtained from water. There are basically two ways in which the hydrogen atoms can be stripped away from the water molecule. Water can be electrolyzed by passing an electric current through it, de- composing the water to hydrogen and oxygen. This is a process which is well known in the chemical industry. Or the decomposition may be accomplished bythermalmeans, that is, by heating the water to tempera- tures high enough that dissociation will take place. The temperature needed for thermal dissociation of water maybe lowered by various chem- ical schemes in which a series of intermediate steps are employed, none of which require the extremely high temperatures needed for direct ther- mal dissociation. One of these schemes, developed by De Beni and Marchetti, two Italian scientists, consists of a series of reactions as follows: 1) Hydrolysis CaBI2 + 2H20 ) Ca(OH)~ + 2HBr 2) Reduction to Hydrogen Hg + 2HBr 250cC >HgBr2+ H2 3) Dehydration HgBr~ + Ca(OH)2 2OO~ >CaBI2 ± HgO + H~J 4) Decomposition HgO E~OOcC ) Hg + 1/2 02 Whose sum is: H~D ->H2+l/202 PAGENO="1085" 1079 CRS - 4 The advantage of this thermochemical scheme, as opposed to direct ther- mal decomposition, is that the maximum temperature required is only 730°C, as opposed to the 25OCPto 3000°C needed for direct thermal cracking of water. However, this system is only experimental at this time, and there are likely to be a number of difficult design problems to be overcome before such a system can be put into practical use. Whether the means of decomposition of water is electrical or thermal, energy is required in order to make this decomposition take place. Many advocates of the use of `alternative energy sources" such as solar, geo- thermal, wind power or ocean thermal energy visualize the hydrogen economy as a natural tie-in to these new sources of energy. Some effective storage system, such as hydrogen generation and storage, is essential for such alternative energy sources because of their intermittent nature. By oversizing the generating plants, they can be used to generate more hydrogen than needed during their running cycles. During the off cycles (no wind or no sun), the stored hydrogen is used to sustain a constant power output. However, a virtually non-depletable nuclear system (breeders or fusion) would serve a "hydrogen economy" equally well. 2. Transportation and Storage of Hydrogen. The hydrogen produced by the electrolytic or thermal methods described above must be trans- ported to the large urban centers and other areas where energy is needed. One means of transporting this hydrogen would be by pumping it through a network of pipelines. The natural gas pipelines already in existence in the United States and Canada could be usedas part of a hydrogen trans- mission network. Hydrogen could be pumped through these pipelines either as a gas under pressure or, if insulation problems could be overcome, PAGENO="1086" 1080 CRS-5 as a cryogenic liquid. Tankers could also be used for the transportati~n of gaseous or liquid hydrogen where port facilities are available. Storage of hydrogen has always been a problem. Hydrogen has a high leakage rate relative to other gases, and tends to embrittle the metals being used to contain it. As a gas it has a very low density for a given pressure compared to other gases, hence requiring either larger storage vessels or higher pressures than would be required for a given weight of any other gas. As a liquid the volume requirements are less than for a gas, but the energy requirements for liquefying hydrogen, and the insulation requirements for keeping it in the liquid state, are both for- midable. Hydrogen may be reacted with metals to form compounds known as metal hydrides. The metal hydride method of hydrogen storage is particularly intriguing, since it would store hydrogen at a density com- parable to that of liquid hydrogen but without the cryogenic requirements of liquid hydrogen, and presumably without the leakage and embrittlement problems of gaseous hydrogen. However, the practical feasibility of storing large quantities of hydrogen in this manner has yet to be demon- strated. 3. Ultimate Use of Hydrogen. Perhaps the first use of hydrogen in a major way, according to "hydrogen economy" proponents, would be as a supplement to existing electrical utility systems used to meet peak load requirements. In this application, hydrogen would be stored (as electricity cannot now be) until the time of peak electrical power demand. It would then be used in fuel cells to generate electricity. In addition to the production of electricity, it has been proposed that hydrogen could be used as a fuel for household heating and cooking, as an automobile fuel, as an aviation fuel, and in other industrial, residential, PAGENO="1087" 1081 CRS - 6 and transportation applications. All of the uses listed here are theoret- ically feasible. However, it should be remembered that most of them would involve a fairly extensive redesign of the appliances and equipment in which hydrogen is intended to replace conventional energy sources. C. The `Hydrogen Economy" - - Underlying Assumptions The merit of the "hydrogen economy" concept rests on two ideas. First, that the transportable combustibles (fossil fuels) must someday be replaced by another transportable combustible due to the exhaustion of fossil fuels. Second, that there are essentially non-depletable sources of energy which are not suitable as portable energy sources. Combining the two ideas, the "hydrogen economy" suggests that non-depletable energy sources such as solar or nuclear could be applied to produce a distributable and portable substitute for fossil fuels - - namely hydrogen. Furthermore, it is suggested that the non-depletable nature of the energy sources makes the unfavorable energy cost ratio to produce hydrogen relatively unimpor- tant. Key points from studies and proposals for a hydrogen economy may be summarized as follows: 1. Timing. Is this a possible scenario belonging to a far distant future or something requiring immediate planning? Advocates of the hy- drogen economy urge early action. They base their recommendation on the idea that fossil fuel exhaustion is in sight and/or that hydrogen com- bustion produces none of the polluting by-products associated with the use of fossil fuels. 2. Technical Aspects. What are the technical problems associated with the substitution of hydrogen for fossil fuels? Proponents of the PAGENO="1088" 1082 CRS - 7 hydrogen economy see no severe limitation on its widespread use. Oice generated by an essentially non-depletable energy source (nuclear or solar), they suggest that stationary consumption needs (power plants, factories and homes) could be served through the existing pipeline net- works. They feel that long distance gas pumping is more efficient than modern electrical power transmission lines and propose that pipelines be substituted for overhead wiring systems as a more efficient as well as a more aesthetic means of transmitting energy. Portable fuel re- quirements (vehicular), they feel, could also be served through the use of compressed gas in tanks, cryogenic hydrogen or hydrogen stored in metal powder (hydrides). 3. Economics of Supply. How expensive must fossil fuel become to make an alternative fuel, such as hydrogen, economically feasible? Advocates for the hydrogen economy generally take the position that a near term depletion of fossil fuel will force the development of the hydrogen alternative, thus making this question irrelevant. Their eco- nomic concerns are therefore directed toward the funding of programs to discover new ways to release hydrogen, e. g. from water, in lieu of today's source, whici; involves the consumption of fossil fuels. ID. The Nature of Hydrogen 1. Properties. Hydrogen, chemical symbol H, is the lightest and most abundant chemical element in the universe. Hydrogen accounts for an estimated 75% of all the mass in the universe, or about 90% of all the atoms. The thermonuclear reactions that convert hydrogen to helium are responsible for the energy of the Sun and the other stars. PAGENO="1089" 1083 CRS - 8 Hydrogen is the first element in the periodic table, which means that it is the lightest of all the elements. Hydrogen boils at -253°C and melts at ~259ct under normal pressure, both of these figures being quite close to the absolute zero figure of -273'C. Because of its light weight, free hydrogen is almost nonexistent on Earth, since this planet's tem- peratures are high enough to cause hydrogen in the atmosphere to "boil away" and escape into space. However, hydrogen is extremely plentiful on Earth, as it readily combines with oxygen to form a chemical com- pound we all know as water (H ~J). On a weight basis, one-ninth of all the water on Earth consists of hydrogen. Hydrogen is also commonly found in compounds with carbon and nitrogen. 2. History. Hydrogen was first isolated by Sir Henry Cavendish, the British chemist, in 1776. Because he noted that a mixture of hydro- gen and air explodes to form water vapor, he called the new element "inflammable air". In 1783 the French chemist Antoine Lavoisier gave the element the name "hydrogen", meaning water-former. 3. Sources of Hydrogen. Under today's conditions, hydrogen is ob- tamed more cheaply from hydrocarbon fuels than it would be by dissocia- ting the water molecule. Therefore, hydrogen today is obtained primarily from the petrochemical industry. Several different methods are commer- cially employed. In the catalytic steam-hydrocarbon reforming process, methane, ethane, and other light hydrocarbons are treated with steam in the presence of a nickel catalyst at temperatures ranging from 6500 to 9800 C to produce hydrogen and oxides of carbon. In anOther process, hydrocarbons are burned with oxygen-lean gas mixtures in internal com- bustion engines to produce hydrogen and carbon monoxide. A third method, 62-332 0 - 76 - 69 PAGENO="1090" 1084 CRS - 9 now rarely used, is to obtain hydrogen from the purification of coke-uven gas. The high cost of coke has tended to make this method economically obsolete. 4. Uses of Hydrogen. The largest single use of hydrogen at the pres- ent time is in the synthesis of ammonia. It is estimated that, as of 1965, two-thirds of the total world hydrogen production was used in am- monia manufacture. (Total world hydrogen production as of that year was 81 billion cubic meters, or 6. 510 million metric tons.) The second largestuse of hydrogen is in petroleum refinery operations, wherehydro- genation processes play a major role in the transformation of crude oil to useful products. The third largest use for hydrogen is in the pro- duction of methanol. The first major use of hydrogen as a fuel has been in the space pro- gram. Liquid hydrogen is burned with oxygen to produce the tremendous amounts of thrust needed to lift a rocket with ~a payload into Earth orbit or on its way to the moon. Some upper stages of the Saturn rocket, which has been the backbone of the NASA manned space exploration program, are powered by liquid hydrogen and liquid oxygen. The production capacity of 160 tons per day of liquid hydrogen, which was placed in operation by 1964, was primarily for the requirements of the space program. 5. Unique Problems Associated with Hydrogen. Hydrogen has some special characteristics which tend to make its storage and handling more difficult than most materials. The extremely small size of the hydrogen molecule enables it to "find' and escape through the tiniest openings in the container or pipeline in which it is being held; so small is the mole- cule that it can escape through the molecular structure of most materials. Thus hydrogen will always have a leakage rate higher than that for other PAGENO="1091" 1085 CRS - 10 fuel gases. Hydrogen tends to "attack" metals by a phenomenon known as hydrogen embrittlement. This phenomenon, the mechanics of which are rather poorly understood, weakens the container or pipeline holding the hydrogen and makes relatively frequent replacement of metal sur- faces exposed to hydrogen necessary. The extremely low temperature needed to liquify hydrogen makes its transportation and use as a liquid very difficult. On the other hand its low density as a gas means that large volume amounts of H2 must be pumped to supply a given weight of fuel (or, alternatively, the hydrogen must be pumped at very high pres- sures). 1/ Finally, hydrogen of course is flammable, and burns ex- plosively under certain conditions. The dangers associated with the flam- mability of hydrogen have probably been exaggerated in the public mind, as a result of the "Hindenburg" disaster of 1937 in which the German airship of that name exploded and burned at Lakehurst, New Jersey, killing 36 persons. Any fuel is by definition flammable, and hydrogen is no more hazardous than other fuels if handled properly. In fact, its high diffusion rate tends to diminish the explosion hazard for hydrogen as compared to other fuels. However, the "public image" of hydrogen as an explosive and dangerous material may itself be a problem. 1 / Under standard conditions one pound of H2 gas occupies 200 cubic - feet and provides 51, 600 BTU of energy. A pound of liquid H2 occupies 0. 23 cubic feet and also provides 51, 600 BTU. A pound of gasoline occupies 0. 023 cubic feet and provides 19, 100 BTU. Thus, on a volume basis, a given volume of gasoline would require roughly 3. 75 times that volume of liquid hydrogen, or 3200 times that volume of hydrogen gas under standard conditions, to produce the same amount of energy. PAGENO="1092" 1086 CRS -11 E. Hydrogen Research Today At the present time there is a small but significant amount of re- search under way on the use of hydrogen as a fuel. Most of this work is concentrated in the area of transportation, i. e. using hydrogen as a fuel source for automobiles and aircraft. In this section we will outline three of the more significant research programs under way in this area. This section is by no means aU-inclusii~e, since hydrogen research is now taking place in a number of laboratories and other research insti- tutions, in the Government, in universities, and in private industry. Our intention here is to highlight this research, focusing particularly on projects where laboratory testing is actually under way, as opposed to `~paper" studies. 1. NASA Automobile Engine Project. The National Aeronautics and Space Administration (NASA) has begun a feasibility study of an internal combustion engine which uses hydrogen in combination with conventional gasoline to power an automobile. In the NASA project, gasoline is catalytically cracked to generate hydrogen and other gases. The hydro- gen and other gases are then mixed with additional gasoline in the car- buretor, and the hydrogen-gasoline mixture is used to power an automo- bile engine. At the present time, the hydrogen generator is being developed at NASA's Lewis Researąh Center. Pending its completion, NASA's Jet Propulsion Laboratory is the site fOr experimental work in which bottled hydrogen gas is used to prove the feasibility of using hydrogen as an automotive fuel. The bottled hydrogen has been carbureted with gasoline to operate a Chevrolet automobile. Early test results are highly en- couraging, as they seem to indicate that the hydrogen injeōtion process PAGENO="1093" 1087 CRS - 12 significantly boosts engine efficiency and cuts pollution emissions. The exhaust product from the experimental engine is mostly water vapor and other harmless components. 2. AEC Metal Hydride Project. The Atomic Energy Commission (AEC) is~ .fąk~ng a different approach involving the use of metal hydrides. Metal hydrides can be stored more easily, more safely, and with poten- tially less volume required than for gaseous or liquid hydrogen. The most promising metals being tested for this purpose appear to be a manganese- nickel alloy and an iron-titanium alloy. In use, the metal hydride would be stored in the vehicle in powdered form. When heated by a heat ex- changer using water from the car's radiator, the hydride decomposes, producing hydrogen gas which is burned in the engine. The metallic powder could be recycled to reform the metal hydride when exhausted. As of this date, the AEC experimenters have not tested the metal hy- dride concept in an automobile. However, they have demonstrated the first use of the storage concept by using metal hydrides as a "hydrogen reser- voir" for a power company, on an experimental basis. The ~ reservoir" was built by AEC researchers at Brookhaven National Labora- tory on Long Island for the Public Service Electric and Gas Company. Hydrogen is produced by electrolysis of water, and stored as iron titanium hydride in a pressure vessel. It is then released to a fuel-cell stack, where it is combined with oxygen to produce energy. Tests so far have shown that the hydrogen reservoir has exceeded its design specifications as an energy storage system. 3. Hydrogen as an Aviation Fuel. The concept of a hydrogen-fueled aircraft has received increasing attention in the technical literature, in advanced planning by NASA, and in congressional hearings. The fuel PAGENO="1094" 1088 CRS - 13 shortage of early 1974 added to the interest in hydrogen as an alternative to present aviation fuels. NASA has placed a number .of small study con- tracts on the subject, and the agency is reportedly considering the modi- fication of two Lockheed C-14l jet transports into experimental hydrogen- powered test beds. 2/ Hydrogen as an aviation fuel would have certain advantages, such as higher combustion efficiency and lower pollution levels than exist for to- day's kerosene-based fuels. And the goal of achieving independence from the suppliers of crude oil is important in this as in every other field. However, the use of hydrogen in aircraft is not without its drawbacks, the most serious of which is probably the very low density of hydrogen. Even using liquid hydrogen (gaseous hydrogen is out of the question for this application), 3. 75 times the volume of hydrogen is required to pro- .duce the same energy equivalent as a given volume of existing jet fuel. This would cause serious problems in aircraft design. Handling the cryo- genic liquid hydrogen would be an additional problem. There is also the "change-over" problem of developing the network of supplies and airport facilities necessary `to support a world-wide system of hydrogen powered aircraft. NASA's considerations of the use of hydrogen as an aircraft fuel have considered primarily the combustion properties and aerody- namic problems. They have not addressed the issue of where the hydrogen would come from for an operating airline system. On balance, the hydrogen powered fleet concept will remain an academic exercise until the hydrogen supply issue is faced. 2/ Aviation Week and Space Technology, Dec. 17, 1973, p. 38. PAGENO="1095" 1089 CRS - 14 4. Federally Sponsored Hydrogen Research Today - - Spending Levels. Hydrogen research today, insofar as the Federal Government is concerned, is scattered through a large number of Government agencies, and is being funded at a rather low level in all of these agencies. The following table shows the amount being spent on hydrogen research,, by agency and by fiscal year, for fiscal years 1974 and 1975. (The FY 1975 figures are estimates). HYDROGEN RESEARCH SPENDING -- FY 1974 and FY 1975 3/ (Figures in thousands of dollars) Agency FY `74 FY `75 Atomic Energy Commission $ 1030 $ 2500 National Science Foundation 100 600 National Aeronautics and Space Administration 1735 1100 Environmental Protection Agency 100 100 Department of Transportation 100 100, Advanced Research Projects Agency (Dept. of Defense) 250 250 National Bureau of Standards (Dept. of Commerce) 210 200 Total $ 3525 $ 4850 5. Expert Opinions on Projected Future Spending Levels for Hydrogen Research. A number of scientists who are active in the field of hydrogen research were queried as to their ideas of a. reasonable fund- ing level for a national hydrogen research program over the next five fis- cal years. Their responses varied widely, ranging from a low estimate. of $2-5 million per year to a high of $50-265 million per year. The estimate of $2-5 million per year came from Dr. W. . H. McCulloch of Sandia Laboratories. Dr. Derek P. Gregory of the Institute of Gas Tech-. nology estimated a figure of $7-b million per year. Dr. W. E. Winsche 3/ Estimates collected from agency officials. PAGENO="1096" 1090 CRS - 15 and Dr. J. J. Reilly, both of AECs Brookhaven Laboratories, suggested $20 million per year. Dr. Howard P. Harrenstein of the University of Miami suggested an ambitious program which would begin at $50 million for the first fiscal year and escalate to $265 million for the last of the five fiscal years. His program would total $680 million over the five- year period, or an average of $136 million per year. Dr. Edward M. Dickson of Stanford Research Institute declined to answer the question at this time, stating that his analysis was as yet too incomplete for him to respond. Dr. Dickson is engaged in a technology assessment study of the hydrogen economy concept for the National Science Foundation. His study has not yet been completed, but in telephone conversation with us he expressed strong skepticism as to the usefulness of the Thydrogen economy' idea, as opposed to more readily available sources of new energy such as oil shale and coal. PAGENO="1097" 1091 CRS - 16 II. FEASIBILITY OF THE `HYDROGEN ECONOMY" A. Hydrogen Compared with Electricity The ultimate success or failure of the "hydrogen ~conomy" concept will depend upon not only the technical feasibility of the concept, but upon its economic practicality as well. At this early point comments on the economics of the system must necessarily be tentative, general, and subject to change as more is learned about the strengths and weak- nesses of the concept. With these cautionary notes in mind, the following comments can be made: Hydrogen, as we have stated, is basically an energy storage and dis- tribution system, taking energy from a primary power source, such as a nuclear or solar energy plant, and transporting it to an energy-use area, such as a factory or large city. Therefore, it must be compared in terms of economic feasibility with electrical power distribution systems, which constitute our present method of distributing power. The comparison of hydrogen with electricity discloses certain advantages for each, as fol- lows: Advantages for Hydrogen. The cost of transmission of power through an underground hydrogen pipeline has been estimated, by hydrogen propo- nents, to be far lower than the cost of transmitting an equivalent amount of power by overhead electric cable. This is particularly true for long distances, i.e. greater than 200-300 miles. One estimate is that the cost of transmitting energy as hydrogen might be from 113 to 1/10 the cost of an equivalent overhead power line. Hydrogen pipelines also have aesthetic and environmental advantages as compared to overhead electrical PAGENO="1098" 1092 CRS - 17 lines with their accompanying towers, though it is difficult to quantify such advantages in terms of an economic value. Finally, hydrogen can be stored for peak-use periods, while it is now impossible to do this with electricity. Generating hydrogen by electrolysis during off-peak cycles, storing it, then using it as fuel during peak cycles is possible, although costly in terms of overall fuel consumption. Advantages for Electricity. The technology and the distribution sys- tem for electricity already exist, whereas that for hydrogen is yet to be developed. Hydrogen is more costly to produce than is electrical energy. It is highly unlikely that home appliances will ever be hydrogen-powered, thus much of the hydrogen to be distributed will have to be converted back to electrical energy at or near its point of use. Insofar as this is true, the hydrogen economy" will involve using electricity (or thermal energy) to make hydrogen at point A, then using hydrogen to make elec- tricity at point B. This kind of operation involves sizable losses in effi- ciency and is therefore wasteful of energy. At this point it is impossible to say whether the lower transmission costs and storage capabilities of hydrogen will be significant enough to overbalance the higher production costs and energy inefficiencies asso- ciated with the hydrogen power distribution system. B. The "Hydrogen Economy" - - Critical Questions Assessment of the merit of the hydrogen economy concept requires examination of the following questions: 1. Timing. No one questions that the supply of fossil fuels is finite and non-renewable. Information on the magnitude of the remaining sup- plies tends to be obscured by technical and economic jargon, e..g' such questions as when does a "deposit" become a "known reserve". Some PAGENO="1099" 1093 CRS - 18 estimates of remaining supplies forecast exhaustion in twenty years while others show that man has hardly touched the total supply. The wide variation is due largely to the ground rules used by a particular fore- caster on what he will include. An examination of these issues is essential for establishing an approximate time when planning for an alternative fuel should be done. New supplies of oil and gas have been located under the northern seas and in other areas characterized by hostile climatic conditions. Fuels obtained and transported from such sites will show a cost trend higher than that obtained from less remote sites and from areas with less difficult climatic conditions. These factors and other equally complex techno- logical as well as political variables add too many unknowns to project how much fuel prices will increase with time. However, an upward trend is a certainty. When the costs of using (not just producing) an equally effective al- ternative fuel become less than the costs of using conventional fuels, then the alternative fuel becomes attractive. It is not possible at this time to make a projection which will locate a time in the future when the cost of using hydrogen will become less than the cost of using con- ventional fuels. This is partly because of the previously mentioned prob-. lem in projecting the rising costs of conventional fuels. The other prob- lem is the unknown cost of producing hydrogen. 2. Costs. Large quantities of hydrogen are produced today, but it is generated through the use of fossil fuels. It is a condition of the hy- drogen economy that water, not fossil fuels be the feed stock, and this process is more costly. Techniques for obtaining hydrogen from water PAGENO="1100" 1094 CRS - 19 e being researched at this time. Prospects appear favorable that methods will emerge which will require less energy than straight elec- trolysis. However, results to date have not indicated that methods using water as a feedstock will produce hydrogen at a lower cost than today's methods which involve the use of fossil fuels. An examination of hydrogen costs as produced today and some pro- jections of hydrogen costs produced from water as a feedstock provide a perspective which permits a tentative comparison of the ultimate cost to the consumer of water-derived hydrogen as opposed to fossil fuels. In the study performed by Lotker, Fein, and Salzano in 1973 (op. cit.), the total production cost for hydrogen produced from fossil fuels was estimated at $1. 27 per million BTU's of energy, assuming an oil price of $4 per barrel. The production cost for hydrogen produced by elec- trolysis of water was estimated at $4. 20 per million BTU's of energy, assuming the cost of electricity to be 10 mills per kilowatt hour. The oil and electricity prices quoted here have increased greatly since this study was performed, because of the rapid rise in the price of oil and of all forms of energy. However the ratio of hydrogen costs from water vs hydrocarbons should remain about the same or about 3 to 1. The ultimate cost of hydrogen to the user is of course higher than the cost of production, since transmission and distribution costs must be added. A look at NASA's experience may be useful, since NASA has used relatively large amounts of liquid hydrogen over the past few years. The cost to NASA of this liquid hydrogen was 35 cents per pound in 1967, and has since riser to $1. 00 per pound. These figures correspond to $6. 80 per million BTU and $19.40 per million BTU, respectively. Using electrolysis, today's hydrogen costs would be about $60. 00 per million PAGENO="1101" 1095 CRS - 20 BTU, assuming the 3 to 1 cost ratio mentioned above. By way of com- parison, one gallon of automotive gasoline, selling for 60 cents at the gas pump, delivers 130, 000 BTUs of energy. Thus the energy cost of gasoline as sold to the consumer is $4. 60 per million BTU at today's prices, compared to a probable $60 per million BTU for water-derived hydrogen. In summary, using the ground rule of the hydrogen economy, that the feedstock for hydrogen must be water, hydrogen is more than twelve times as costly as gasoline. Stated another way, hydrogen would become attractive as a competitor to gasoline only when the price of gasoline increases by a factor of 12, or hydrogen production costs drop in a corres - ponding scale. Two final considerations should be added to these approximations. Hydrogen, if produced in great quantities as is gasoline, could probably be produced for less than 12 times the cost of gasoline. However, the price comparison does not consider the costs or problems of distributing hydrogen nor the costs of systems which can accept it for use once dis- tributed. All of these costs are included in the gasoline pricing. C. Forecast The cost of producing an alternative fuel is only a part of the total cost. A determination must be made of how well the new fuel matches the system which has been developed for the conventional fuels it is to replace. From the earlier discussion, it is clear that there is almost no commonality between today's fuel distribution and storage system and one that hydrogen would require. 1. Vehicular Use. As a portable fuel, the inherent bulk of hydrogen, even as a cryogenic, presents problems severe enough to make the fuel PAGENO="1102" 1096 CRS - 21 impractical for applications other than space vehicles and possibly air- craft. A standard automobile gasoline tank with a 20 gallon capacity occu- pies about three cubic feet. An equivalent quantity of cryogenic hydrogen requires over 10 cubic feet. However, instead of a simple sheet metal box, the tank for liquid hydrogen becomes an insulated flask for carrying liquid at -253°C. Even with near perfect insulation, the hydrogen will boil away at the rate of about 1% per day. Indoor parking would thus be dangerous and there are also serious questions about the crash safety of vehicles carrying liquid hydrogen. A more efficient alternative, in terms of gas conservation would be to store the hydrogen under high pressure, 20 atmospheres or so, in pressure tanks. Although this solution does away with the problems asso- ciated with portable cryogenics, it introduced an equally serious weight and bulk problem. A hundred cubic feet would be required (to hold hy- drogen at 3000 p. s. i.) to equal a 3 cubic foot tank of gasoline. The steel tanks for this would about equal the amount of steel required to make the automobile. The space to store them would equal the interior volume of the average full size sedan. Again the issue of safety is pres- ent in any vehicle transporting cylinders pressurized to this level. On the whole, the issues of cost, bulk and safety render the compressed hydrogen storage method somewhat impractical. A third storage system, the use of hydrides, would require about 10 cubic feet to equal the fuel capacity of a 20 gallon gasoline tank. The bulk problem, using hydrides, is no worse than that presented by the cryogenic solution, and the extreme bulk and safety hazard associated with the compressed gas solution is largely eliminated. The hydride PAGENO="1103" 1097 CRS - 22 tanks are always positively pressurized at about 500 p. s. i. for a fresh tank, falling to about 10 p. s. i. for a spent tank. 4/ A container of hydride can store more hydrogen than the same con- tainer filled with liquid hydrogen. Moreover it is stored in a stable and safe way. The hydride gives up its hydrogen when heated. Of the several hydrides, iron-titanium hydride has the best charging and heat-release characteristics. Iron-titanium will release hydrogen smoothly with nothing more than the waste heat supplied by the engine radiator. Other hydrides require much more heat and would necessitate the use of part of the stored fuel to obtain the needed heat. However, the hydrides are heavy. The preferred iron-titanium hy- dride, to equal the capacity of a 20 gallon gasoline tank, would weigh 23 times as much as the gasoline or about 3, 200 pounds. This would about double the metal content, and weight of an average car. The weight would amount to an unacceptable penalty on fuel mileage, performance and other mechanical systems, such as brakes, and tires. In short, the hydride power car would be a choice between a very short range ve- hicle (hydrides equal to 5 gallons of gasoline would weigh 800 pounds) or an ex±remely heavy vehicle which would sacrifice fuel economy be- cause of weight. While hydrogen, as a portable fuel, does not appear to be an acceptable solution, it could be used as a basic feed stock to produce articicial methane, methanol, or even gasoline. Given a future in which natural hydrocarbons are no longer practically available, and in which a non- depletable power source is available, vehicular needs for fuel could be 4/ For iron-titanium hydride PAGENO="1104" 1098 CRS - 23 met by the manufacture of artificial hydrocarbons. In other words, while the technically elegant solution of generating and using hydrogen directly for all energy requirements may not be a practical one, hydrogen still may play a significant (though indirect) role in meeting our future needs for vehicular fuel. 2. Stationary Uses of Hydrogen Power. Hydrogen generation offers a potential solution to the primary handicap of all intermittent energy sources such as wind and other forms of solar energy. Although the storage of hydrogen is difficult, its storage does not present the almost insurmountable problems to a stationary plant that it does to vehicular use. This paper will not examine the practicality of constructing plants which use various forms of solar energy, but should such plants exist in the future, the intermittent nature of their energy production would make an energy storage system, probably involving the generation and use of hydrogen, virtually a necessity for their practical operation. While the generation and storage of hydrogen may be necessary for a solar energy plant, the use of a nuclear fusion plant or any other con- stant power producer to generate hydrogen, which is then transported by some means for use by other stationary plants, may be challenged. More than twice the energy in a given volume of hydrogen gas must be applied to water to free the hydrogen. 5/ The energy applied to the water is electrical energy. If the hydrogen is then transported to be- come the fuel of another generating plant, three BTU of hydrogen must 5 / According to G. Strickland, Brookhaven Laboratory, the Teledyne electrolyzer requires 33 kilowatts of power to produce one pound of hydrogen. The maximum power theoretically obtainable from a pound of hydrogen is 15 KW, hence the ratio of roughly 2 to 1. PAGENO="1105" 1099 CRS - 24 be consumed for one BTU equivalent in electricity produced. Multiplying these figures together, we find that 2x3 = 6 BTTJ of electricity needed per BTU of electricity provided. 6/ Allowing for power consumption for transporting the hydrogen, approximately 7 BTU would be required for each electrical BTTJ equivalent drawn by the final consumer with current technology. The direct generation and transmission of elec- tricity, even at a 50% penalty due to transmission line losses, would require only 2 BTU of electricity consumed per BTTJ of electricity pro- *duced. This is less than one third of the amount of energy required for a given quantity of electricity in the hydrogen system (approximating one half if the hydrogen system uses fuel cells). 6 / If fuel cells come into practical use, conversion of hydrogen to elec- - trical power may reach or exceed an efficiency of 50%. There would then be 2x2, or 4 BTU of electricity needed per BTU of electricity produced. 62-332 0 - 76 - 70 PAGENO="1106" 1100 CRS-25 III. CONCLUSIONS The "hydrogen economy, if it is defined as an energy system which is to totally displace present methods of energy storage, present fuels, and present methods of energy transportation, must be viewed as an un- necessarily impractical scenario. A forecast of the worst possible energy future would call for 1) a depletion of all fossil fuels, 2) a failure to create either a successful breeder reactor or a fusion system, 3) a de- pletion of fission fuels and 4) a complete dependence on wind and other solar systems to generate hydrogen. In these circumstances, the hydrogen pipeline network, as proposed by the advocates of the hydrogen economy, might be the most effective means of distributing energy to stationary plants. (Fuel cells to gener- ate electricity from hydrogen at the seacoast, followed by conventional transmission of electricity, would stifi have to be considered.) How- ever, as discussed earlier, it would not be necessary to penalize ve- hicles with the excessive weight and material problems imposed by using hydrogen. As to the materials problem, enough iron-titanium hydride to outfit today's aLpi~ti.ų~- of r~-cars (about `5~ million) would exceed this nation' s total output of steel by more than an order of mag- nitude. Since less titanium is currently produced than steel by a factor of roughly 200, titanium would face an even more severe supply shortage than iron. 7/ The alternative would therefore be the use of the hydro- gen to produce artificial hydrocarbon fuels similar to those in use today. 7/ World Almanac, 1974, pp. 108-109. (1972 figures for U. S. production) PAGENO="1107" 1101 CRS-26 In this worst of possible energy scenarios, a "hydrogen economy" could come into being but it would lack the comprehensive simplicity and the awkwardness of the one popularly proposed. Two factors challenge the prospect that this bleak energy scenario, in which hydrogen is produced exclusively by forms of solar energy, will ever exist. These are 1) the number of years before the continued use of fossil fuel becomes impractical and 2) the success of nuclear research and development. Many forecasts have been completed which anticipate depletion times for fossil fuel. Some forecast that world oil supplies could dry up in no more than 30 more years, while others contend that petrochemical fuels will be available for several hundredyears, after which coal derived liquid fuels will add many hundred more years. Most of the forecasts are price oriented, not quantity oriented, a characteristic the reader is often left to imply. As oil or gas becomes more difficult to obtain or to transport, the price rises. Also, as the price rises, known deposits of oil formerly considered too costly to exploit suddenly become profit- able and are added to the column called "known reserves". Exploration for new deposits in the oceans and arctic regions, areas previously ig- nored because potential finds could not compete with low cost oil, become attractive at higher oil prices. Further increases in oil prices cross the point at which oil shale and tar sands become economically feasible resources. When this point is reached, the world's known reserves increase by a factor of about three. A little beyond this pricing level, the production of portable liquid fuels from coal becomes practical. PAGENO="1108" 1102 CRS - 27 From these observations it seems clear that the availability of petro- chemicals is related more to selling price than to the actual quantity in the earth. Projecting further, the pricing trend over the next century or two could be expected to reach the point where the manufacture of ar- tificial fuels resembling gasoline and kerosene, using hydrogen as a feedstock, could become economically desirable - - on the condition that the hydrogen is separated from water with power from some non-deplet- able source. One such power supply, the slow breeder reactor, already exists and is in service as a naval vessel power plant. Thus it appears likely that the art of producing artificial fuels from hydrogen feedstock will be developed well before we need it. Even this, however, will not be the "hydrogen economy" as it is described today by its advocates. PAGENO="1109" 1103 CRS-28 IV. BIBLIOGRAPHY Conference Proceedings. The Hydrogen Economy Miami Energy (THEME) Conference, March 18-20, 1974, Miami Beach, Florida, ed. by T. Nejat Veziroglu, University of Miami, Corabl Gables, Florida. De Boni, Gianfranco, and Cesare Marchetti. Hydrogen, key to the energy market. Euro-Spectra magazine, March 1970, PP. 46-50. Dickson, E. M., et al. The use of hydrogen in commercial aircraft - - an assessment. Paper prepared for the 9th Intersociety Energy Conversion Engineering Conference, San Francisco, August 1974, 11 p. Gregory, Derek P. Status of R&D related to the production, transpor- tation, and utilization of hydrogen as a fuel. Testimony presented at hearings held by the Subcommittee on Science, Research, and De- velopment, Committee on Science and Astronautics, U. S. House of Representatives, on "Energy Research and Development", May, 1972, / pp. 487-492. Hdrrenstein,\ Howard P. The hydrogen economy - - a state of the art (Unpub1i~hed paper) 28 p. University of Miami, Coral Gables, Florida, 1974. Hydrogen energy: a bibliography with abstracts, cumulative volume (1953-1973), Jan. 1, 1974, ed. by Kenneth E. Cox, Energy Infor- / mation Center, University of New Mexico, Albuquerque, New Mexico. J4~essing, Lawrence. The coming hydrogen economy. Fortune, Nov. / 1972: 138-146. Lotker, Michael, Elthu Fein, and F. J~ Salzano. The hydrogen economy - - a utility perspective. Paper prepared for presentation at the Institute of Electrical and Electronics Engineers Power Engineering Society Winter Meeting, New York, N. Y., Jan. 27-Feb. 1, 1974, 9 p. Reilly, J. J., K. C. Hoffman, G. Strickland, and R. H. Wiswall. Iron titanium hydride as a source of hydrogen fuel for stationary and automotive applications. Paper presented at the 26th Power Sources Symposium, Atlantic City, N. J., April 1974, 14 p. Winsche, W. E., K. C. Hoffman, and F. J. Salzano. Hydrogen: its future role in the nation's energy economy. Science magazine, v. 180, June 29, 1973: 1325-1332. The wonder fuel, Newsweek, Nov. 12, 1973: 75. SP 358 PAGENO="1110" 1104 (Reprinted from Science 6 June 1975, volume 188, pages 1036-1037) THERMOCHEMICAL HYDROGEN GENERATION: HEAT REQUIREMENTS AND COSTS The costs and energy requirements of the processes for thermochemical hydro- gen generation presented by Wentorf and Hanneman (1) are so grossly under- estimated that it is highly questionable whether these thermochemical processes can compete with other hydrogen generation techniques. To demonstrate this I will discuss process B presented in (1), although the comments apply equally well to the other two processes discussed by Wentorf and Hanneman and to very similar cycles proposed in (2) and (3). The chemical reactions and the thermo- dynamic data used in (1) are given in Table 1, together with the estimated heat requirements. A simple thermodynamic argument shows that, if the heat requirements anl thermal efficiencies were really as reported by Wentorf and Hanneman, we could build a perpetuum mobile of the second type. Assume that we have three heat sources, at temperatures T1=lOO° C, T~=35O° C, and THI=600° C. We could now build a power plant by using process B to split water, drawing heat Q from these reservoirs, and then reacting the hydrogen with oxygen in an ideal fuel cell, neglecting all irreversible losses. For each mole of 112 produced we will get 57 kcal of electricity, using 30 kcal from source I, 26.5 kcal from source II, and 30 kcal from source III. On the other hand, an ideal Carnot engine would generate only 37.4 kcal of electricity: ~G~Qlnput(lTamb1ent/T1nput)3O(13O0°/3730)+ 26.5(l-330°/623°) +30(1_3000/8730 ) =37.4 kcal (where ~G is the Gibbs free energy charge, and Tomblent and T~0~0~ are given in degrees Kelvin). Thus process B violates the second law of thermodynamics. What the authors neglect is the vast energies of separation [see (4)], which are even larger than appear from the above, as it is also necessary to generate the free energy lost in step B4. Otherwise. we could improve on the above perpetuum mobile by using step B4 to generate electricity in a fuel cell. TABLE 1.-THERMODYNAMIC DATA AND HEAT REQUIREMENTS FROM (L) Energies (kcal) for Reaction reactions as written temperature Step Reaction (°C) ~J30 ~G° Heat requirements 1 B1 2Cu(c)~2HCl(aq)-42CuCI(c)+H2(g) 100° -~8 2 B2 4CuCI(c)-22C0CI2(c)+2Cu(c) 30 _1000 30 38 30 kcal at 1000 C. B3 2CuCI2(c)-42CuCI(c)+C12(g) 500 -600° 30 0 30 kcal at 600° C. B4 C12(g)+Ng(OH)2(aq)-4MgCI2(aq)+H20(I)+ 80° -038 046 3'~O2(g). B5 MgCI2(c)+2H2O(g)-OMg(OH)2(c)+2HCI(g)_ - - - 350° 4 8 26.5 kcal at 350° C. Irreversible losses 15 kcal. Total heat input 101.5 kcal. 1 The heat required for the production of 1 mole of H2. Copyright at 1975 by the American Association for the Advancement of Science. We have estimated the minimum separation work to be 37 kcal for process B arid 45 kcal for process A. The separation processes generating this free energy are all carried out at low temperatures. In current practice, their real efficiences (L~G/Q) are below 5 percent. The authors also underestimate the large irrevers- ible heat loss incurred in heating the process streams to reaction temperature. The overall thermal efficiency for any of tile three processes should be closer to 5 percent than to the 50 percent given. Thermal efficiencies by themselves mean very little as no process can improve on the theoretical efficiency of electrolysis. It is the cost of obtaining it that counts. To put the cost in proper perspective, an ideal mass balance to produce 106 British thermal units (1 Btu=O.95 kj=O.25 kcal) of hydrogen fuel or 16 pounds (`1 pound=454 g) of 112 is given below (the units are those used in Ameri- can industry). To produce 101 Btu worth, or 16 pounds of 112, we would have to hydrolyze about 0.4 ton (1 ton=908 kg) of MgCI2 at high temperature w4th steam; mann- PAGENO="1111" 1105 facture 1 ton of concentrated hydrochloric acid (30 percent) ; dissolve 0.5 ton of copper ~ hydrochloric acid; disproportionate about 1.6 tons of CuC1 in aqueous dispersion into CuC12 and Cu, with all the associated steps; crystallize 1.4 tons of Cu~12~ 2H20 in a multiple evaporator crystallizer; dry 1.4 tons of Cu~l2~2H2O and drive off the water of crystallization; and melt, decompose, solidify, and cool 1.15 tons of `CuC12-not to mention all the filtering, washing, scrubbing, and distillation steps, `the magnitude of `which is mind-boggling! All this is to be accomplished at an irreversible heat loss and energy requirement of only 200,000 Btu, or 15 percent of the stoichiometric heats of reaction, and a total heat re- quirement of about 2.1 X 106 Btu. The capital and operating expenses. for this enormous plant are said to be more than $1 per 106 Btu of hydrogen, which is certainly a correct although misleading statement since Wentorf and Hanneman claim that the process can compete with electrolysis, `which suggests that the total cost is expected to be somewhere `between $6 and $10 per 106 Btu. How can one expect any such thing if `comparison with the thermal efficiencies and costs of similar processes clearly lead to costs and heat requirements at least one order of magnitude larger? The hydrolysis of MgC12 mentioned above is a commercial process, and `the present heat requirements and co'st of `this s'tep alone would account for the total mentioned `by Wen'torf and Hanneman. Let us examine the disproportiona- tion of CuCl into Cu and CuC12, which `is the crucial `step. The heat requirement, given `by Wen'torf `and Hanneman, is 440,000 B'tu. The equilibrium concentration of CuC12 in `the presence of CuC1 in slightly acid aqueous solution is 0.3 g per liter. In `two of `the options mentioned we would need to treat 900,000 gallons (1 gal- lon=3.8 liters) of water for each 106 Btu of IL generated. Wentorf and Han- neman state that the heat needed for `the evaporation of water can be regained by condensation with "only a small loss." What does this mean? In the best equipment sold by the General Electric Company, the heat requirement for the evaporation of 900,000 gallons of water in a multiple-step evaporator would be 600X 106 Btu. If there is a way to evaporate water with small loss, let's forget about generating hydrogen and concentrate on watering the desert, since we are talking about the equivalent of desalinating 10° gallons of brackish water! Even `if we were to find a very efficient chelating agent, the heat needed would still be 2X 106 Btu in addition to the heat of reaction-and this in order to make 106 Btu worth of H2! Even if we did not have `to worry a'bout the `low equilibrium concentration, the mere crystallizing of 1.15 tons of CuCl2 from a concentrated acid solution and drying it would require well a'bove 108 Btu, and involve capital and operating costs well above $5, making the whole process questionable jus't on `the basis of this `one idealized `step alone. A'nd so on. In `the presen't state of the art, an optimistic cost estim'ate for process B would be close to $100 for 108 Btu of hydrogen or more than $600 for the fuel equivalent of one `barrel of oil. This plant would be so `big that it is doubtful that we could recover the energy invested in its construction. None of the other processes de- scribed in (1) seems much better. We are not dealing here with some unknown future technology but with chem- ical and physical steps very similar to industrial processes tha't are at present widely u'sed. If we are to find better processes for the generation of hydrogen as well as for any `other new energy source, the research for them must be based on proper realistic estimates of heat and cos't requirements. R. SHINNAR, Departnvent of Chemical Engineering, City College of the City University of New York. REFERENCES 1. R. H. Wentorf, Jr., and H. E. Hanneman, yeie'nee 185, 311 (1974). 2. C. M'archetti, Civem. Econ. Eng. Rev. (1974), p. 288. 3. R. E. Chao, md. Eng. cihern. Prod. Res. Dev. 13, 94 (1974). 4. J. E. Funk `and R. M. Reinstrom, md. Eng. Chem. Process Des. Dcv. 5, 336 (1966). 30 August 1974; revised 30 December 1974 PAGENO="1112" 1106 OAX RIDGE NATIONAL LABORATORY, Oak Ridge, Tenn., Sept ember 16, 1975. Mr. WIL SMITH, Subcommittee on Energy Research Developnien t and Deni onstration, U.S. House of Representatives, TVashington, D.C. DEAR MR. SMITH: I am enclosing a reprint of our recent publication on hydrogen, "Hydrogen: A Versatile Element" by C. E. Bamberger and J. Braun- stein, Am. Sd. 63. #4, 438 (1975), hoping it may be useful to the Subcommittee on Energy Research, Development and Demonstration. This paper reviews the present state of development of hydrogen production and uses, and the corre- sponding expectations for the near future. Since our publication is rather long, it may be useful to point out our opinions; these follow: The production of hydrogen via thermochemical decomposition of water is theoretically capable of being more efficient and/or less pollutant than the production by electrolysis or by using coal directly. The thermochemical pro- duction of hydrogen is achieved at high temperatures (less than 10000 C) ; thus, a prin1ary source of energy capable of delivering the required heat is necessary. Presently primarily nuclear energy and, to a lesser extent, solar concentration appear to be viable heat sources. Thermochemical methods are still being de- veloped in the laboratory (our area of expertise) and are not yet ready for engineering-scale development. The uncertainty associated with the future de- velopment and cost of "dedicated" sources of primary energy and of suitable thermochemical plants obviously allows only for estimates of hydrogen costs. These estimates may be rather inaccurate and will not permit unequivocal conclusions regarding competitiveness of different methods of production. Although many applications and uses have been proposed for hydrogen as a secondary source of energy and energy transmission agent, it is my contention that the present and future need for ammonia-based fertilizers alone warrants an enlarged effort (over present levels) on research devoted to developing novel methods of hydrogen production. If I can be of any help, I would be happy to provide my assistance. Yours truly, C. BAMBERGER, Chemistry Division. Enclosure. PAGENO="1113" 1107 Reprinted from AMERICAN SCIENTIST[ Vol. 63, No.4, July-August 1975, pp. 438-447 Copyright © 1975 by Sigma Xi, The Scientific Research Society of North America, Incorporated PAGENO="1114" 1108 C. E. Bamberger J. Braunstein Hydrogen: A Versatile Element~ Hydrogen generated from water may prove very valuable in extending the world's dwindling hydrocarbon supply The present energy crisis through- out the world has emphasized the grave geopolitical consequences of the uneven distribution of the world's raw materials, especially fuels. Another salient fact is the pollution of the environment from the ever-increasing consumption of oil and coal. Because hydiogen, in water, is one of the most abundant and widely distributed elements on the earth's surface, and because the Drs. Bamberger and Braunstein are re- search staff members of the Oak Ridge Na- tional Loboratory. Dr. Bomberger received his doctorate in chemistry in 1958 from the Universidad Nacional de Buenos Aires, Ar- gentina. Prior to 1966 he was the head of the Division of Beryllium Chemistry at the Comisiod Nacional de Energ'ia Atbmica, in Argentina, and he spent 1961-63 at ORNL on a fellowship from the International Atomic Energy Agency. He has performed research in beryllium chemistry and physi- cal chemistry of molten fluorides and is at present working on the development of ther- mochemical methods for the production of hydrogen. He has coauthored over 30 tech- nical publications, holds several patents, and is a contributor to the series Advances in Molten Salt Chemistry. Dr. Braunstein received his undergraduate degree at the City College of New York and his doctoral degree from Northwestern Uni- versity. Prior to joining ORNL in 1966. he was Professor of Chemistry at the Unwersi- ty of Maine. He has publishcd in the areas of theoretical chemistry and electrolyte physical chemistry. In addition to his cur- rent research on molten salts and concen- trated aqueous electrolytes, he coedits Ad- vances in Molten Salt Chemistry, lectures at the University of Tennessee-Oak Ridge Graduate School of Biomedical Sciences, and has contributed to the 1972 reporl, Hy- drogen and Other Synthetic Fuels, for the Federal Council on Science and Technology. The authors wish to express their apprecia- tion to J. W. Michel, of ORNL, for his help- ful suggestions on this paper. Their research is sponsored by the Energy and Research Development Administration under contract with the Union Carbide Corporation. Ad- dress: Oak Ridge National Laboratory, P.O. Box X, Oak Ridge, Tennessee 37830. burning of hydrogen mErely pro- duces water again, with no deleteri- ous effects on the environment, we should not be surprised that many scientists consider this element po- tentially an ideal general fuel. Stat- ed so simply, the concept can be misleading, because hydrogen is not ci primary fuel; energy must be ex- pended in order to decompose the water. A country can be indepen- dent of foreign oil and/or coal im- ports only if it has an available al- ternate primary source of energy. However, even if a nation lacks such a source, its hydrogen output can be very useful both in an ener- gy transfer capacity and as a means of making more efficient use of classical fuels. Hitherto, most hydrogen has been produced by the decomposition of natural hydrocarbons and, to a much lesser extent, by the electrol- ysis of water. Owing to dwindling oil and natural gas reserves, new sources and methods for producing hydrogen must be developed. This need will be augmented by the de- mands of both traditional and new processes requiring hydrogen-for example, the ammonia and coal liquefaction and gasification indus- tries. Clearly, water appears to be the best source for hydrogen, and at present solar and nuclear energy are the most promising primary sources for its decomposition; the former is inexhaustible and the lat- ter is virtually so if breeder reactors are used. Some proponents of a "hydrogen economy" foresee the use of hydro- gen not only as a fuel for industrial and home heating but as a means for energy storage and distribution as well, Strong arguments are made that the production of hydrogen on a large scale would permit a cheap- er widespread distribution of energy than the present distribution of electricity. Today it seems more re- alistic to predict that a hydrogen economy will begin with the pro- duction of hydrogen by large-scale electrolysis plants, using electricity generated with nuclear reactors. This hydrogen can be used near its production site, for example in am- monia manufacture and steel pro- duction. The storage and transmis- sion of hydrogen and, more impor- tant, its generation by thermo- chemical cycles can then be devel- oped concurrently. At present, the two major consum- ers of hydrogen are the ammonia and petrochemical industries. Or- ganic synthesis and hydrogenation of oil and fats constitute the third largest use. Because these applica- tions are well known, we will con- centrate on those uses likely to grow to importance in the future: energy transmission, peak shaving or load leveling (the use of storage of electrical energy during times when supply exceeds demand), coal liquefaction and gasification, fuel for industrial furnaces, domestic appliances and transportation, and reduction of iron ore to produce steel. Hydrogen production Because of the many variables that affect estimates of future hydrogen production, we will select only a few of the most reliable figures. Ac- cording to the U.S. Bureau of Mines (1970), world consumption of hydrogen in 1968 was 6.6 million tons, with 4.4 million tons con- sumed in the U.S. More than 75% PAGENO="1115" of the world production was used for ammonia synthesis; the U.S. used 42% for this purpose alone. Marchetti (1971) indicates that in 1970 the world production reached 17 million tons. Bureau of Mines predictions of demand for hydrogen in the U.S. by the year 2000 range between 30 and 112 million tons, according to different assumed values for annual growth rates of 6.5% and 10.5%, respectively. Simi- lar predictions for world demand for hydrogen by 2000 range from 55 to 140 million tons. These extrapo- lations may be conservative be- cause they probably give heavy weight to the contribution of the current 5-6% annual growth rate for ammonia production. The cost of hydrogen has changed rapidly during the last two years owing to changes in cost of primary sources of energy. The range of esti- mated costs in the future varies widely according to the proposed method of production, especially since thermochemical cycles have not yet been established. The cal- culated cost of these cycles may vary from $1 to approximately $7 per million Btu (1 cu ft of hydrogen produces 325 Btu). It is conceivable that changes in the living habits of entire segments of the population, brought about by improvements in public transporta- tion, recycling of now-wasted mate- rials, and the like, could lead to lower fuel demands than indicated above. However, the growth of world population and its needs for food are inescapable facts that point to an ever-increasing demand for ammonia-based fertilizers and thus to an unequivocal need for more hydrogen. Since the beginning of the twenti- eth century the technology of hy- drogen production has changed considerably, owing in large part to the continuously growing demand for the product. Initially, electroly- sis of aqueous solutions was used. This was followed in the mid 1920s by the endothermic water-gas cata- lytic process, in which steam is passed over incandescent coal. The water-gas (CO + H2) obtained is further mixed with steam and passed over iron or cobalt oxide catalysts at 400CC, producing CO2 and H2. The CO2 is removed by 1109 washing with water or other sol- vents under pressure, and the resid- ual CO is removed with a cuprous chloride ammonia solution. Another method used extensively is the steam-hydrocarbon process, which is carried out at tempera- tures of 1,100CC and produces CO and H2. As this reaction is also en- dothermic, the heat is usually sup- plied by adding oxygen and burn- ing part of the hydrocarbons. Al- though this process is still used in countries with large supplies of light hydrocarbons, it is4easonable to assume that its application will drop significantly in the future. Electrolysis of water proceeds via the passage of an electric current through water by means of inert electrodes. As water is virtually a nonconductor, an electrolyte-gen- erally KOH-is added. Equivalent amounts of oxygen and hydrogen are liberated at the anode and cathode, respectively. Both the liq- uid and the porous separators in the electrolytic cell prevent mixing of the two gases, which can be col- lected at any convenient pressure. The minimum electrical energy re- quired to decompose water is pro- portional to the Gibbs free energy of water decomposition (which is the negative of the free energy of formation of water from the ele- ments), and because this figure de- creases with increasing tempera- ture, the voltage and electrical en- ergy required decrease also, but only slowly. The resistivity of the electrolyte and the electrode over- voltage also decrease; however, the additional heat required to main- tain the higher operating tempera- tures partially counteracts this ad- vantage. Electrolytic processes in which water vapor is electrolyzed show promise of improved efficiency (Chem. Eng. News, 4 Nov. 1968, 27 Aug. 1973). Such systems employ solid electrolytes, for example ox- ide-conductive zirconia or proton- conductive sulfonic acid polymers, as membranes separating the liber- ated oxygen and hydrogen. The oxide cells operate at very high temperatures, - 1,100CC, while the polymer cells operate at slightly above 100CC. A similar principle has been proposed for hydrogen production in an open cycle, in which coal char is burned to carbon monoxide and the heat of combus- tion is used to vaporize water (Wentorf and Hanneman 1974). The steam and CO are passed over opposite sides of a conductive solid electrolyte; CO is oxidized to CO2 and discarded; and the steam is re- duced to H2, while oxide ions (and electrons) pass through the electro- lyte. Although overall thermal ef- ficiencies of 60-70% are claimed, large-scale hydrogen production will probably require further atten- tion to closed cycles. Thermochemical cycles, which are comprised of a series of chemical reactions at various temperatures, decompose water and permit the complete recycling of all other reac- tants. The net result is the con- sumption of energy and water and the production of hydrogen and oxygen. Hybrid cycles, although less well known, are those in which some reactions proceed by the input of thermal energy, and at least one reaction is effected by ra- diation or electrical energy. In order to be economically advantageous, these cycles obviously require a sig- nificantly lower consumption of electrical energy than that needed for the complete. electrolysis of water. Research on thermochemical cycles is still in the early stages of development. Although one such cycle* was sug- gested as early as 1924 (Brit. Pat. 232,431; 1924), it did not seem to stir much interest, probably for the obvious reason of the small demand for hydrogen at that time. Now, fifty years later, the situation has changed, and scientists have start- ed to take a closer look at the feasi- bility of thermochemical cycles for producing hydrogen. In a study for the U.S. Army, Funk and Rein- strom (1966) laid the groundwork for this concept, developing the theoretical basis of the processes and arriving at the conclusion that the conversion efficiencies of ther- mochemical cycles are limited by the highest and lowest tempera- ture, in the manner of the Carnot cycle. They also found that, with currently known chemical com- pounds, there was no available two-step cycle, a conclusion that still appears to be valid. In 1970, DeBeni, Marchetti, and their asso- ciates publicized the feasibility of using thermochemical cycles for PAGENO="1116" splitting water into its components. Finally, the "energy crisis" of 1973 brought wide attention to the con- cept, and efforts to seek and test thermochemical cycles were initiat- ed in many nations. Since thermochemical cycles are Carnot-limited, a thermodynamic analysis of the energy requirements and conversion efficiencies is cru- cial in guiding the search for useful processes. Thus, whether a thermo- chemical cycle can be found that will approach theoretical Carnot (maximum) conversion efficiencies more closely than a steam-elec- tric-electrolytic cycle depends on the chemical steps in the thermo- chemical cycle. Since conventional steam electric-generation plants operate not on a Carnot cycle but on the less efficient Rankine cycle, it is conceivable (although certainly not established) that a thermo- chemical cycle could more closely approach the efficiency of the limit- ing Carnot cycle than conventional cycles. Also, in eliminating the electrolytic process, losses of effi- ciency deriving from irreversibili- ties, such as the overvoltage of the cell, are bypassed. Furthermore, even a new lower-efficiency process may still have an economic advan- tage over a conventional process if the capital costs of the plant are lower. Such reduced capital costs are a possibility, since a plant in- volving chemical processes only may well be less expensive than one employing electrical generation and electrolytic equipment. Because of the large scale of required hydrogen production, even a small relative cost reduction could bring enor- mous dollar savings. As pointed out by Funk and his colleagues, there is a key thermody- namic criterion for finding thermo- chemical cycles with optimum en- ergy requirements: reactions in high-temperature steps of the cycle should proceed with an increase of entropy (as might be the case if more chemical bonds are broken than are formed), while the lower temperature steps should be those with a decrease of entropy. Details of the thermodynamic analysis and definition of the efficiencies, or fig- ures of merit, of cycles have been ditcussed by Funk and Reinstrom (1966), Knoche and Schubert (1973), Abraham and Schreiner 1110 (1974), and Wentorf and Hanne- man (1974). In order to accomplish a thermo- chemical cycle, compounds of an element of variable valence are gen- erally required in addition to the hydrogen and oxygen of water. A cursory examination of the periodic table reveals that, although many elements exhibit variable valence, the useful number decreases to less than thirty when abundance and cost are taken into account. Fur- thermore, only a limited number of inorganic hydrogen-bearing com- pounds, when reduced, will release their hydrogen. Among such com- pounds, the halogen acids and the alkali and alkaline earth hydroxides are the main candidates; acids such as H2504 or HNO3 release SO2 or NOx, respectively, which is usually undesirable. Research centers in Europe, Japan, and the U.S. apply similar criteria in selecting limiting parameters in their search, for thermochemical cy- cles. These cycles should have as few steps as possible and involve simple physical and mechanical separations, thus minimizing ex- tensive use of mechanical or electri- cal energy. The acceptable upper limit of temperature varies, the most frequent choice being around 1,000CC, which researchers consider achievable with the next generation of reactors. Barnert and Schulten (1974) have indicated that, even if nuclear reactors achieve tempera- tures as high as l,400-1,800'C in the future, the acceptable upper limits for cycle temperatures will be restricted by the materials of con- struction of heat exchangers and other components of the system. It is reasonable to postulate that the thermochemical cycles should use compounds of elements that are now in ample supply and are not expected to become scarce. Some researchers, taking exception to this point, argue that the materials are completely regenerated, and cy- cles have thus been proposed using mercury (Marchetti 1973) and sil- ver (Dorner and Keller 1974). Also, the problem of materials compati- bility must be considered when de- veloping a cycle; exotic materials, even if available, will substantially increase capital and production costs. Different approaches are being used in the search for feasible cycles, ranging from computer calculations of reaction yields to purely experi- mental tests of reactions conceived for this purpose or reported in the open literature for others. The pre- ferred approach seems to be a com- bination of both extremes: perform- ing calculations of yields of reac- tions for which there are reliable thermochemical data together with experimental testing of the reac- tions required to close a cycle for which the data either do not exist or are dubious. Using computer programs, DeBeni (1974), collabo- rating with Knoche and Hardy- Grena, has studied cycles which would use iron oxides and chlorides and has obtained 361 possible cy- cles involving a maximum of 5 reactions each. For additional dis- cussion of the various computer programs, we refer the reader to Pangborn and Sharer (1974) and Russell and Porter (1974). While it is an invaluable informa- tion-organizing tool, the high-speed computer does not circumvent the need for reliable data on the ener- getics of candidate reactants. Many potential reactants are among classes of compounds for which thermodynamic data are nonexis- tent or quite inaccurate, the latter because they date from the period when modern methods of charac- terization were unavailable. At Oak Ridge, we have used the more time- consuming experimental approach because it yields direct information on the reaction and its rate and be- cause it also makes possible an un- equivocal identification of the reac- tion products. This approach is ob- viously capable of giving direct es- timates of formation-free energies of compounds for which no data exist. Once the equilibrium quotients and their temperature dependence have either been established experimen- tally or calculated from reliable sources, the efficiency of a cycle can be estimated using computer pro- grams. Of the approximately 30 thermochemical cycles published (see Dorner and Schnurr 1974 and Chao 1974 for a review), two illus- trate the range of compounds and temperatures studied. Tip to now the reported cycles have been clas- sified by the number of steps in- PAGENO="1117" volved or by the highest tempera- ture required. As the number of proposed cycles increases, it may be useful to develop a more informa- tive system of classification based on the symbols or atomic numbers of the elements involved. The most publicized cycle, known as Mark I, was developed by DeBe- ni and Marchetti (1970) and con- sists of the following reactions: 730'C CaBr2 + 2H20 = Ca(OH)2 + 2HBr (Al) 2HBr + Hg =CHgBr2 + H2 (A2) HgBr, + Ca(OH)2 =CCaBr2 + H20 + HgO (A3) HgOHg + 1/202 (A4) This cycle seems to present prob- lems of corrosion of construction materials and of slow kinetics for reaction (A2); however, the dispro. portionation of HgBr formed in the course of reaction (A2) produces finely divided mercury which, the authors claim, leads to a faster reaction and a lower required tem- perature. There are variations of Mark I using copper instead of mercury, and strontium instead of calcium (Euratom Staff 1973). Among the thermochemical cycles requiring 5 chemical reactions, Mark 7, credited to Hardy-Grena (1973), has the merit of using only elements in abundant supply, namely iron and chlorine. 3Fe903 + 18HC1 LOC + 9H90 (Bi) 6FeCl3 4~6FeCl2 + 3Cl2 (B2) 650'C 6FeCl9 + 8H20 = 2Fe304 + 12HC1 + 2H2 (B3) 2Fe304 + 1/202 ~ 3Fe203 (B4) 3H0 + 3Cl2 800'C 6HC1 + 3/202 (B5) At the indicated temperatures, reactions (Bi), (B4), and (B5) have negative free energies of reaction, indicating spontaneity, but (B2) and (B3) have positive values, +8.54 and +26.65 kcal, respective- ly, indicating low equilibrium con- centrations of products. Hardy- Primary sources of energy There are a number of primary sources of energy that can be used to produce hydrogen. Some might be used in a dual capacity: sun- light, for example, can be used as a source of heat for thermochemical cycles or to generate electricity di- rectly, by the photovoltaic effect, for water electrolysis. Steam, from geothermal power, and other sources such as wind, tidal power, and hydraulic power are, at pres- ent, used only to generate electric- ity; but the electricity produced can be used to electrolyze water and produce hydrogen. The general problem with most of the mentioned sources (all derived from solar energy) is that the com- bined systems of energy collector and electrical generator are usually located, by their nature, far from population or industrial centers. The electricity, which is generated intermittently, must be transmit- Wind. Solar energy in the form of wind is an inexhaustible and non- polluting source but suffers the dis- advantages of its intermittent na- ture, the large land areas required, and the noise pollution generated by present-day turbines. During the 1940s and 1950s extensive research on wind turbines improved their performance, and aerodynamic studies are still in progress (Base 1974). Several windmills have been constructed that generate up to 100 kW, and there are designs for ca- pacities near 4,000 kW. The eco- nomic attractiveness of windmills for generating large amounts of en- ergy will depend on how the gener- ated electricity will be used and whether it will be stored as such or as hydrogen. Oceanic thermal gradients. Exploi- tation of oceanic thermal gradients has been considered for more than 50 years. Implementation requires an evaporator near the surface, a condenser with a "cold" water input from a depth of 300-1,000 meters, a pump, and a turbine. These plants would be located near the tropics, where temperature gra- dients of about 25CC are found, giv- ing a difference of about 12CC be- tween the condenser and the evapo- rator. They would produce electric- ity that could be transmitted to land as such or in the form of hy- drogen. One disadvantage of these power plants is the extremely large size dictated by their low maxi- mum theoretical efficiency of 3.5%, 1111 Grena has also proposed several ted over long distances, with an variations of the above cycle, all of economic penalty, or it must be which use some of the reactions of stored. No economical solution, Mark 7, including (B5). Further such as adequate batteries, is pres. study is needed to find a suitable ently available for such storage. catalyst which will speed this reac- Hydrogen, on the other hand, is tion and to simplify the separation emerging as a possible solution to of reactants and products. both problems. Its costs of trans- mission by pipeline have been esti- In a report prepared for the U.S. mated to be competitive with, or Federal Council on Science and even lower than, those of electric- Technology R&D Goals Study, the ity; and hydrogen can be stored in Synthetic Fuels Panel (1972) con- many forms: as a cryogenic liquid, cluded that "although thermo- as a gas under pressure, or in metal chemical methods of producing by- hydrides-solid chemical com- drogen from reactor heat do not ap- pounds from which the hydrogen pear likely to result in large savings can be recovered by heating. Al- compared with the electrolytic though the uses and limitations of route, even a 1% advantage would primary sources of energy have result in an annual savings ap- been reviewed extensively else- proaching $1 billion, because of the where, a brief summary (omitting large scale, of production if natural fossil fuels) is given here in the con- gas and gasoline are replaced by text of hydrogen production. hydrogen or hydrogen-based syn- thetic fuels. This potential saving would seem to justify a consider- able amount of research." Although the possibility of a 1% saving might be questionable-and its demon- stration will require a very high de- gree of accuracy-it nevertheless supports strongly the need for reli- able data on equilibrium constants, energy requirements for separation processes, and so forth. PAGENO="1118" with an overall efficiency of 2 ±0.2%. At present there are many problems-e.g. structural, hydrody- namic, and materials compatibility with chemical and marine biologi- cal environments-which require further studies. Solar energy. While solar energy has its enthusiastic supporters (Heronemus 1974), its detractors emphasize its intermittent nature, its limited availability owing to cli- matic conditions, and the inordi- nately large land areas required, all of which raise questions about the totrl cost and the environmental impact of large-scale development. Experiments with parabolic reflec- tors indicate that temperatures in excess of 3.500CC can be attained, and large solar furnaces are pres- ently being built with heliostats- flat mirrors that follow the sun and reflect its light into a fixed parabol- ic concentrator. Although the direct thermal decomposition of water at these elevated temperatures is ther- modynamically feasible, it poses se- vere practical problems-the sepa- ration of the decomposition prod- ucts and the availability of stable suitable materials. Based on present knowledge, it appears more practi- cal, although perhaps not more economical, to build solar collectors which would reach lower tempera- tures-in the range of 600-1,000~C -and to use the heat to generate either electricity or thermochemical hydrogen. Calculations by Hildebrandt and Vant-Hull (1974) indicate that a receiver atop a 450 m tower collect- ing the energy reflected by mirrors over 45% of an area of 2.6 km2 (1 sq mi) located at 35~N latitude could collect as much as 2,700 MWhr-thermal per day in midwin- ter and approximately twice that amount in summer. The tempera- ture achievable at the collector is in excess of 1,000CC. Other physical methods of using solar energy in- volve its direct conversion to elec- tricity, for example, by means of the thermoelectric or photovoltaic effect. Thus, hydrogen could, in principle, be produced by electroly- sis, using electrical energy generat- ed directly from solar energy. Photosynthesis is the best-known use of solar energy, and research on photosynthetic mechanisms is gain- ing renewed interest because of their possible application to the de- composition of water. Although the photoproduction of hydrogen by algae was first reported in 1942 by Gaifron and Rubin and that by photosynthetic bacteria in 1949 by Gest and Kamen, the subject has not been extensively studied from the point of view of hydrogen pro- duction until recently. Mitsui (1974) has proposed a program of screening tropical and subtropical marine photosynthetic algae and bacteria for the selection of cell sys- tems which could produce hydro- gen. The next step, after a success- ful selection, would be the develop- ment of hydrogen production from cell-free systems. Although other attractive schemes have been pro- posed (Mortenson et al. 1962; Val- entine et al. 1963; Benemann et al. 1973; Benemann and Weare 1974), it should be kept in mind that at present they seem to offer no real advantage over thermochemical processes. Nuclear Energy. Energy released in nuclear fission appears to be the leading primary source for the pro- duction of hydrogen because avail- able reactor designs are capable of reaching the upper temperatures required and because fission reactor technology has advanced further than that of other energy sources. The leading fission reactor design for the production of hydrogen by thermochemical cycles is the high- temperature gas-cooled reactor (HTGR), because it reaches higher temperatures (950CC) at the heat exchanger than other designs. The concept of applying HTGRS to the generation of hydrogen is being de- veloped mainly in Germany, the U.S., and Japan. The application of nuclear heat is not without problems, however. In addition to compatibility difficul- ties between the construction mate- rials used for heat exchangers and the chemicals used for thermogen- eration of hydrogen, reactors gener- ate tritium, a radioactive heavy iso- tope of hydrogen which can be haz- ardous to living things. It can be generated in the fission process and by neutron activation of impurities in the moderator and in the pri- mary coolant. Barnert and Schul- ten (1974) have concluded that this problem can be managed within environmentally tolerable limits, estimating that a 3,000 MW-ther- mal reactor would produce 700 curies of tritium per year, virtually all of which diffuses into the heat exchanger at temperatures close to 1,000CC. If the endothermic high temperature reaction used is oxy- gen evolution, the tritium would be oxidized to tritiated water (HTO), which could be separated and dis- posed of without difficulty. If, how- ever, the endothermic reaction is the hydrogen evolution step, then the tritium would end up mixed with hydrogen. Barnert and Schul- ten (1974) have estimated that the tritium produced in hydrogen gen- eration with such a large reactor would be so diluted that its activity would be acceptably low. However, since the effects of very small doses are still under debate, sometimes as quite emotional issues, the safest and most expedient solution would be to reduce the diffusion of tritium through the heat-exchanger walls or to select cycles in which the high- temperature step permits the re- moval of tritium as a compound, most likely tritiated water. Other reactor designs, some of which have been tested experimen- tally for brief periods, could be de- veloped to provide heat for water splitting. The Rover, a reactor de- veloped at Los Alamos for nuclear rocket propulsion, has operated at temperatures up to 2,300CC for up to 10 hours, and the UHTREX (Ultra High Temperature Reactor Experiment) reactor, designed to heat the helium coolant to about 1,300CC, operated for 30 days (Booth and Balcomb 1973). Molten salt reactors (Grimes and Bamber- ger 1970), which have been de- signed for electrical power genera- tion and operate at temperatures below 700CC, could conceivably op- erate at even higher temperatures with further development of con- struction materials. In order to use them for the production of hydro- gen, however, it is first necessary to solve the problem of their high rate of tritium production. Current re- search may lower significantly the diffusion of tritium into the steam and find means for trapping it in the secondary coolant. It thus appears that only HTGRS are suitable for delivering the nec- essary thermal energy directly from 1112 PAGENO="1119" the helium coolant to a loop con- taining the reactants needed for hy- drogen production. The NASA/ ASEE Report (1973) suggested that thermonuclear, or fusion, reactors can be exploited for the generation of hydrogen in several different ways, among them thermal meth- ods or electrolysis. Photolysis, an- other alternative, would use part of the energy of the plasma to produce ultraviolet light (Chem. & Eng. News, 3 July 1972). Although ther- monuclear reactors may have some potential advantage over fission re- actors, their feasibility has not yet been demonstrated, and they may pose severe tritium-generation problems. Characteristics of hydrogen From the comparative characteris- tics of hydrogen and some of its compounds (see Fig. 1), it can be seen that the heat of combustion of hydrogen, on a weight basis, is more than 3 times that of gasoline and 2.5 times that of methane. Liq- uid hydrogen, however, does not x N >~ compare favorably on a volume basis; to obtain the same heat con- tent as gasoline or methane, a hy- drogen volume 2.5 or 3 times as large is required. One serious problem associated with hydrogen is the potential em- brittlement of metals and alloys used for its containment and trans- port, particularly pipelines (Chan- dler and Walter 1974; NASA/ ASEE 1973). The form of embrit- tlement causing the most immedi- ate concern is hydrogen-environ- ment embrittlement (HEE), which takes place while a metal is ex- posed to a hydrogen environment and results in lower ductility, sur- face cracking, subcritical crack growth, and faster crack-growth rates. The degree of embrittlement increases with the hydrogen pres- sure, although it can be significant even at about 1 atm. While HEE occurs over a wide range of temper- atures, and is greatest near room temperature, it is decreased by rel- atively small concentrations of such impurities as oxygen, carbon diox- ide, or water vapor. Because hydrogen has frequently been proposed as a replacement for electricity as an energy carrier (using existing natural-gas lines for distribution), HEE is a source of concern. The proponents of such a use for hydrogen argue that hydro- gen pipelines have been in opera- tion in Texas and in the Ruhr area of Germany with no apparent deg- radation of the metals, probably owing to the relatively low hydro- gen pressures used (about 10 atm) and the presence of impurities. It is conceivable that in the future hy- drogen for fuel use will be produced and delivered through pipelines at purities no greater than 99.98%, which should suffice for inhibiting HEE. Although the operating con- ditions envisioned for hydrogen pipelines should not jeopardize a hydrogen economy, more research is needed to understand the HEE phenomenon sufficiently to develop a means of avoiding it. As an energy carrier, hydrogen's properties and costs of transmission must be considered in relation to the element in its gaseous and liq- uid state as well as in combustible compounds, such as ammonia, hy- drazine, methane, and methanol. In x N -c 5~ 1113 Figure 1. The energy density characteristics teries include an adjustment for a different of fuels are graphed here on a mass and vol. energy conversion efficiency. (Courtesy of ume basis. The figures for advanced bat. NASA.( Mass-energy U density Volume-energy density 25 gasoline propane methane methanol ammonia hydrogen metal hydride advanced monotone liq. petroleenee liq. CH0 CH3OH liq. NH3 liq. H3 Mg~NiHu batteries C3H,8 gus C3H8 No-S. Li-S 0 PAGENO="1120" this context, ammonia can be con- sidered a hydrogen carrier, and it has some advantages over hydrogen because it does not require cryogen- ic storage (it is currently shipped as a liquid at 10 atm) and it has a greater energy density than liquid hydrogen. Since the combustion of ammonia should ideally produce only nitrogen and water, engineers were prompted to consider its use in internal combustion engines; however, the burning was not com- plete and the exhaust contained re- sidual ammonia, hydrogen, and ni- trogen oxides. Improved results have been reported more recently (Graves et al. 1974), but the prob- lem of unburned ammonia remains to be solved. Some industrial uses of hydrogen- Only a few hydrogen-containing compounds and processes depen- dent on hydrogen are described here; we have limited our selection to the more novel and/or those pre- dicted to have the largest impact on future energy needs. Methanol. The use of methanol (methyl alcohol or wood alcohol) as a fuel is not new; according to Reed and Lerner (1973), 3.2 million tons were produced in the U.S. in 1972, equivalent to 1% of the gasoline produced. During wartime hydro- carbon scarcity, some countries have synthesized it in large amounts from coal. Methanol is especially suited to countries with abundant supplies of coal and ei- ther with or without another pri- mary source of energy, such as nu- clear energy. Thus the U.S., En- gland, Germany, and France could be candidates for the development of a methanol economy. The main synthesis reaction for methanol is 2H2 + CO CH3OH. The hydrogen can be obtained by any of the described methods, but if the reaction of coal with water is used, an excess of CO2 will be formed. In a preliminary study, Steinberg and his colleagues (1973) report the various options for pro- ducing methanol in large quantities using different sources of energy. They arrived at the price of 72t/million Btu, which is quite rea- sonable, by assuming the use of a 1114 conventional coal-burning power plant of 1,000 MW electrical capac- ity, a cost of coal at $8/ton (12,000 Btu/lb), and an electrical conver- sion efficiency of 40%. From Figure 1 it can be seen that the heat of combustion of methanol is only about half that of gasoline on a weight or volume basis; how- ever, this is partially compensated by the fact that methanol burns more efficiently (Steinberg et al. 1973). One of the attractive proper- ties of methanol is its high degree of miscibility with gasoline; at room temperature they are com- pletely miscible, whereas at 0~C less than 10% of the methanol dis- solves in gasoline (although this amount can perhaps be increased by using inexpensive additives). In unmodified cars, the addition of 5-30% methanol to gasoline in- creased fuel economy by 5-13%, de- creased the CO emission by 14-72%, and increased the acceler- ation of the vehicle by up to 7%. If pure methanol were used, only minor modifications, costing an es- timated $100 per car, would be re- quired (Reed and Lerner 1973). The only drawback is the ability of water to extract 10 times its own weight of methanol from gasoline containing 10% methanol; however, this problem can be met by keeping containers and fuel tanks dry. The future of the use of methanol as an additive for gasoline will be con- trolled basically by economic rather than technological considerations. Iron ore reduction. The most im- portant operation in the fabrication of steel and other ferrous alloys is the chemical reduction of iron oxide ore to metallic iron, for which car- bon, from coal, is now mainly used. Although hydrogen has been pro- posed recently as a substitute for carbon in the steel industry (Mar- chetti 1973), the idea is not new; it stems from the past necessities of a totally different market. Only eight years ago the Purofer process was proposed because of the "increasing availability" of natural gas in many parts of the world (von Bogdandy et al. 1966). At that time it was es- timated that the supply of natural gas was so large that it made sense to find ways of utilizing it. The suggestion was then made to reduce irdn ore through the following reac- tions: Fe203 + 3H2 -~- 2Fe + 3H20 Fe03 + 3C0 -`- 2Fe + 3C02 with mixtures of H2 and CO pro- duced by the reaction CH4 + 1/202 -~ CO + 2H2 The many processes for reducing iron ore have been comprehensively reviewed by Wild (1969). World awareness of pollution, rapidly de- creasing supplies of natural hydro- carbons, and the rapidly rising price of coke combine to make hy- drogen a very attractive substitute. Wortberg (1971), investigating the experimental and economic aspects of iron ore reduction with hydrogen obtained by water electrolysis using nuclear energy, found that the re- duction of the iron oxide mineral hematite with hydrogen could reach 95% at 800CC in the presence of silicon carbide or zirconium oxide as inert support materials. He concluded that if vapor-phase elec- trolysis were used to produce hy- drogen, the cost of the process would be low enough to compete with other direct reduction meth- ods. If hydrogen were used in the future as a reductant of iron ore, and if the hydrogen were generated by the energy from a nuclear reac- tor, its impact on the steel industry could encourage construction of nu- clear reactors near the source of the ore, with steel then produced in situ. Coal liquefaction and gasification. Converting coal into a liquid or meltable fuel oil requires the addi- tion ot hydrogen and the removal from the coal of polluting agents such as sulfur and ash. Increasing the hydrogen content of the coal by 2-3% of its total weight (including ash) results in a heavy oil suitable for burning in power plants, while an increase of 6% or more of hydro- gen produces a mixture of lighter oils which can be distilled. Addi- tional hydrogen is required for the removal of impurities. However, at the two given percentages, the yields from coal have been estimat- ed at 3 and 4 barrels of fuel per ton of bituminous coal, respectively. Large-scale coal liquefaction plants have been in operation since the mid 1920s, notably those in Germa- ny during World War II. Today several processes are under research and development. PAGENO="1121" In 1971 the U.S. consumed 6.4 bil- lion m3 of natural gas, a figure which indicates the potential im- portance of coal gasification for countries which have abundant coal supplies. Most established methods for the production of syn- thetic natural gas use coal or naph- tha with steam at high tempera- tures to form methane, the main constituent of natural gas. Three different naphtha processes have been commercialized, differing mainly in the catalysts used. The goal of coal gasification is to optimize the production of meth- ane, and although several processes are available, only the German Lurgi process has been commercial- ized (see Maugh 1972; Bresler and Ireland 1972; and Cover et a!. 1973). While the main drawback of these processes is the abundant generation of C02, direct reaction of hydrogen and carbon could be- come economically attractive if ad- equate catalysts, such as molten salts, could be found. Ammonia, which serves as a nitro- gen carrier in fertilizers, is present- ly made by the Haber-Bosch pro- cess, developed in 1913, in which nitrogen and hydrogen in a molar ratio of 1:3 react in the presence of catalysts at temperatures between 250 and 4005C under pressures varying between 200 and 2,500 atm (Considine 1974). Although the free energy of formation of ammonia be- comes more positive at higher tem- peratures, thus becoming more un- stable, the above conditions pro- vide more favorable kinetics. In the U.S. alone, production of ammonia is approaching 20 million tons/yr. Its price decreased over the last decade from $45/ton to about $25/ton in 1972, but it has now in- creased to $145/ton owing to soar- ing costs of the natural gas and pe- troleum used to provide the hydro- gen and the energy for the synthesis (Synthetic Fuels Panel 1972; Science, 12 July 1974). In the same Science article, G. Sweeney, of Ar- thur D. Little, Inc., is quoted as es- timating that 80% of the cost of manufacturing ammonia is the cost of hydrogen. Although there are contradictory statistics in the Science article about whether the supply of ammonia will meet or even surpass the demand during this decade, it seems evident that the demand for ammonia will keep increasing and, in our opinion, will make its manufacture the most im- portant use of hydrogen in the near future. Interest has been renewed in other methods of ammonia produc- tion, e.g. using sunlight as the source of energy, as in nitrogen fixation by bacteria and blue-green algae (Marx 1974). A number of additional uses for hy- drogen and its compounds are being explored. For example, the heat of combustion of hydrogen is exploited in the Aphodid burner, in which hydrogen is burned by oxy- gen, rather than by air, in the pres- ence of water vapor. This device could be used in steam power plants. Flameless catalytic burners have a wide variety of proposed heating applications (Sharer and Pangborn 1974); the most severe obstacle to their development is the limited availability of adequate catalysts at reasonable cost. This subject is generating some very in- teresting basic research on the elec- tronic structure of catalysts in at- tempts to understand their singular behavior and to synthesize new, less costly materials (Laramore ét al. 1974; Houston et al. 1974; Switendick 1974). The characteris- tics of hydrogen combustion in flames have also been thoroughly studied because of the multiplicity of applications of such combustion systems (NASA/ASEE 1973). Fuel cells, like batteries, transform the energy of a chemical reaction directly into electrical energy (un- like batteries, their fuel supply is external to the cell and is supplied on demand). One of the simplest fuel-cell reactions is that of hydro- gen with oxygen to produce water and electricity; the maximum effi- ciency is about 93% at room tem- perature and decreases slightly with increasing temperature (Tan- tram 1974). Actual current outputs of H2-02 cells usually range from 400-1,500 amperes/m2, with a volt- age close to 0.8 v. When, as in space missions, reliability and low weight override cost considerations as selection criteria, fuel cells are used. Since fuel cells are very effi- cient and virtually pollution free, their development for commercial applications and as one of several energy-storage options should pro- gress at least as rapidly as the de- velopment of cheaper methods of hydrogen production. 1115 * Figure 2. This pickup truck st the Los Als- mos Scientific Laboratory is fueled with warm liquid hydrogen fed through a gas car- burator and a conventional engine. The fuel supply, carried in the 50-galloa aluminum spherical dewar, permits a range of 200 miles. The dewar, which is superinsulated, weighs oaly 100 lbs empty. The truck is parked in front of a larger liquid hydrogen dewar. (Courtesy of the Los Alamos Scien- tific Laboratory.) 62-332 0 - 76 - 71 PAGENO="1122" Transportation applications Although the public is familiar with the use of hydrogen for rocket pro- pulsion, there has been less aware- ness of other recent developments in its use for vehicle propulsion. Car, truck, naval vessel, and air- plane jet motors are being fueled by hydrogen on an experimental basis. Williams (1973) has indicated that hydrogen can be used in conven- tional automobile engines with sim- ple modifications in the carburetor and revised design of the fuel tank. The design criteria for the fuel tank require a reasonable volume and weight, a refueling time of no more than 10 minutes, and adequate safety. After analyzing the choices of fuels based on hydrogen, he con- cluded that liquid hydrogen, also referred to as cryogenic hydrogen, is the best candidate from the point of view of emission control and cost. Although some might react to this conclusion with skepticism, Williams has presented a strong case on the basis of developments in cryogenic engineering and sug- gested implementing the technolo- gy in fleet vehicles, which are ob- viously better candidates than pri- vate vehicles. Edeskuty (1974) also concluded that the use of compressed hydro- gen in automobiles is not practical because the weight of the tank would be approximately 100 times that of the fuel; a 1.5 ton tank would be required for a load of 15 kg of hydrogen, which corresponds to about 15 gal of gasoline. On the other hand, cryogenic hydrogen, on an energy basis, occupies three times the volume of gasoline and poses safety and handling prob- lems. Several experimental vehicles have, and do, run on hydrogen, in- cluding a pickup truck at Los Ala- mos (Fig. 2). Formerly. fueled by gaseous hydrogen, it now runs on liquid hydrogen for the purpose of testing aspects of refueling and handling problems. The belief that cryogenic hydrogen can be handled safely is based on extensive industrial and research experience. Liquid hydrogen is now being shipped in 50,000-liter trac- tor-trailer units, in 90,000 1 rail tank cars, and in barges with ca- pacities near 1 million 1 (Edeskuty 1116 1974). At Los Alamos, more than 125 million I have been handled, with flow rates up to 220,000 1 per minute and storage in dewars of approximately 1.8 million 1 capaci- ty. These facts would support Wil- liams's and Edeskuty's confidence in the near-future feasibility of fueling fleet-owned cars with liquid hydrogen. Conceptually, storage of hydrogen in a vehicle tank in the form of a compound with a metal, as hy- drides (see Fig. 1), is attractive in terms of compactness, ease of han- dling, and reversibility of formation at adequate temperatures. Re- charge of the exhausted bed is ac- complished by contact with pres- surized hydrogen while cooling; the decomposition would be accom- plished by thermal contact of the hydride with the exhaust or radia- tor system of the car. Hence there are strong proponents of this means of hydrogen ground transportation (Waide et al. 1974), despite the current drawbacks of the low ratio of contained hydrogen to total weight and the high heat of forma- tion at ambient temperatures. The latter would necessitate high ex- haust temperatures for decomposi- tion. With trade-offs and further development, a vehicle using hy- drides could provide about the same performance as a gasoline-fueled one. A combination of both storage methods, cryogenic and solid hy- dride, has been developed and ap- plied to an automobile by Billings (1974). The cryogenic container, lo- cated in the trunk space of the car, stores about 4 kg of hydrogen, enough for driving about 160 km. An iron titanium hydride system is located in the area usually occupied by the gasoline tank. Although the two storage systems can be oper- ated independently, the boil-off from the cryogenic tank is trans- ferred to the hydride storage sys- tern. While these research and develop- ment efforts point up the feasibility of hydrogen as a vehicle fuel, Dick- son and his coworkers (1974), using a different assessment approach, conclude that development in this area will fail because hydrogen dis- tribution networks are incompati- ble with those of gasoline. "Because the distribution networks are tech. nically and institutionally resistant to change," they write, "options which require only evolutionary rather than fundamental change are more practical." This problem, together with the risks associated with the handling of hydrogen by several million automobile drivers and service station attendants, leads us to believe that, for vehicu- lar uses, hydrogen will play a role not as the element but rather in the form of compounds such as metha- nol and synthetic hydrocarbons (mixtures analogous to gasoline but not obtained from oil). The use of hydrogen as a fuel is more attractive for aircraft than for automobiles because-in addition to the factors of fuel value, the less- er storage problem on a weight basis, and the reduced handling problem-the stored hydrogen would provide an ideal heat sink for cooling the engines and structure of the airplane. Programs for hydro- gen fueling of subsonic and super- sonic airplanes began in the mid 1950s, and in 1957 the subsonic program was terminated after a successful demonstration. The vol- umetric capacity required for hy- drogen would be approximately ten times larger than that required for conventional jet fuel. Changes from currently available jet fuels to new fuels will require modifications not only in production and distribution logistics but also in airplane design. In studies for the NASA Langley Research Center, Hampton, Va., the Lockheed-California Company has prepared designs for two 400-passenger hydrogen-fueled sub- sonic transports, which are planned for a range of 5,500 nautical miles and are modeled basically on con- ventional jet-fueled aircraft. The first design carries liquid hydrogen in forward and rear fuel tanks with- in the fuselage, and passengers are seated eight abreast in a two-level compartment between the tanks. The second design carries the fuel in two nacelles above the wings, and its more slender fuselage per- mits six-abreast seating. Of the two designs, the first weighs less and uses less energy per passenger-seat mile; however, the second may be more attractive from the point of view of passenger safety and may simplify fueling operations. PAGENO="1123" Korycinsky and Snow (1974) have presented other hydrogen-fueled aircraft designs; and, for supersonic airplanes, they claim possible bene- ficial results, even with the com- promises in aerodynamic design re- quired to utilize liquid hydrogen. Interest in hydrogen as a fuel for airplanes, especially supersonic ones, has revived in the last 2-3 years. It has been estimated that a plane flying at Mach 6 for 8,000 km/day would consume a million tons/yr of hydrogen (Gregory et al. 1972). This figure illustrates how a small number of supersonic planes could increase the need for hydrogen by more than 5% of the 1970 world production. Future of hydrogen research. There is no question that the quot- ed figures for future demands for hydrogen warrant a significant re- search effort on methods of produc- tion and uses for a variety of indus- trial, transportation, and agricul- tural applications. In an economic study of markets for hydrogen, Manne and Marchetti (1974) con- cluded that, because exploratory research on production methods is relatively low in cost, "it would make good sense for the U.S. alone to support 50-100 parallel projects during the next 5 years." (Owing to Japan's singular position in world trade and raw materials supply, we believe that the above statement would also apply to it as well.) Manne and Marchetti also esti- mate, and we concur, that demon- stration plants would be built in the mid 1980s and large commer- cial facilities during the 1990s. Al- though the realization of many of the proposals that lead to a hydro- gen economy depends not only on scientists and engineers but also on economists and politicians, we hope that this review of a versatile ele- ment will stimulate our colleagues to propose new and better solutions to the problems facing the world now and in the future. 248005, Uniseenity nf Minnsi, Coral Gables, FL 33124. These Praceedingo are scheduled for repub- lication undee the title Hydrogen Energy by the Plenum Publishing Corp. Abeaham, B. M., and F. Sobreiner. 1974. Indus. & Eng. Che,n. Fundamentals t3(4):355. Baenert, H., and R. Sehulten. 1974. Oeal comma- Base, T. E. 1974. THEME Conf. Proc., p. St.27. Benemann, J. R., J. A. Beeesuus, N. 0. Kaplan, and M. D. Kamen. 1973. Proc. Nat. Acad. Sci. USA. 70(8):23t7-20. Benemann, J. R., and N. M. Weaee. 1974. Science 184:174. Billings, R. E. 1974. THEME Cosf. Proc., p. S8.5l. Booth, L. A., and J. D. Balcomb. 1973. Nuclear heat and hydrogen in future energy utilization. USAEC Rept. LA-5456.MS (Nov.). Available NTIS. Bresler, S. A., and J. D. Ireland. 1972. Chem. Engn. 79:94. Beit. Patent 232,431 (5, 29, 1924). Chandler, w. T., and R. J. Walter. 1974. THEME Conf. Proc.. p. S6.l5. Chao, R. E. 1974. Judas. Eng. & Chem., Prod. Res. &Decelop. l3)3):94. Chem. Engn. News. 1968. 46:48 (4 Nov.); 1972. 50:17 )3July); 1973. 51:15 (27 Aug.). Considsne, D. M., ed.-in.chief. 1974. Chemical and Process Technology Encyclopedia. N.Y.: McGraoo.Hill, p. 107. Cover, A. E., W. C. Schreiner, and G. T. Shaper. dos. 1973. Chem. Eng. Prog. 69)3):3l. DeBesi, G., and C. Marchetti. 1975. Earospectra 9)2):46. DeBeni. 1974. THEME Conf. Proc., p. Sll.l4. Dickson, E. M., T. J. Logoshetti, J. W. Ryan, and L. W. Weisbecher. 1974. THEME Conf. Proc., p. S8.1. Dome,, S., and C. Keller. 1974. THEME Conf. Proc., p. 53.37. Dome,, S., and W. Schnu,r. 1974. Waoserstoff. gewinnung sos Waooer mittels Reactorwirme. USAEC Rept. KFK 1915 (Feb.). Available NTIS. Edeskuty, F. 1. 1974. Long range eonoiderations and possibilities of hydrogen economy. USAEC Rept. LA-UR-74.528. Euratom Staff. 1973. Hydrogen production from cater uscog nuclear heat. Peog. Rept. No. 3 for period ending Dec. 1972. Ispra, Italy: EURA. TOM Joist Nuclear Research Center. EUR/ C-IS/35/73e. Funk, .1. E., and R. M. Reinstrom. 1966. Indus. & Eng. Chem., ProcesoDeoign and Dec. 5)3(:336. Galleon, H., and J. Robin. 1942. J. Gen Physiol. 26:219. Gent, H. and M.D. Kamen. 1949. Science 109:558. Graves, R. L., J. w. Hodgson, and J. S. Tennans. l974.THEMEConf.Proc.,p.58.l5. Gregory, D. P., D. V. C. Ng, and G. M. Long. 1972. Is Electrochemistry of Cleaner Enciron. ments. J.O'M.Bockris,ed.N.Y.: Plenum. Domes, W. R., and C. E. Bambeegre. 1970. Ener- gia Nuclear (Spain) 14)64): 137. Haedy.Greoa, C. 1973. Decomposition thermique de l'eau a tracers dec cycles chimiques de Ia famille Fe.Cla. USAEC Rept. EUR.4058. Avail. able NTIS. Heronemos, W. 1974. THEME Conf. Proc., p. S7.t Hildebeandt, A. F., and L. L. Vast-Hull. 1974. THEME Conf. Proc., p.Sl.3. Houston, J. E., G. E. Laramoee, and R. L. Pack. 1974. Science 185:258. Knoche, K. F., and J. Schubert. 1973. Verlag. Deut. Ing. Foroch. 549:25. Koeyciouhy, P. F., and D. B. Soon. 1974. THEME Conf.Proe., p. Sl2-1. Laeamoee, G. E., J. E. Houston, and R. L. Park. 1974. THEME Conf. Proc., p.512-41. 1117 Manse, A. S., and C. Marchetti. 1974. Hydrogen: Mechanisms and strategies of market penetra. tion. Paper presented at The Hydrogen Econo- my Miami Energy Congerrncr, March 1974. Not included is the Proceedings. Marchetti,C. 1971. Euroopectra lO)4):117. Marchetti, C. 1973. Chem. Economy and Eng. Rec. (Japan). 5(1(:7 (No. 57). Mars, J. L. 1974. Science 185:132. Maugh, T. H., II. 1972. Science 178:44. Mitsui, A. 1974. THEME Csnf. Proc., p. S5.41. Moetenson, L. E., R. C. Valentine, and J. E. Car. nahan. 1962. Biochem. Biophys. Res. Comm. 7)6(:448. NASA/ASEE Engineering Systems Design Insti- tute. 1973. A Hydrogen Energy Carrier. Vol. 2, Systems Analysis. Houston, Tmsan: Johnson Space Cestee, p.47. Pangboen, J. B., and J. C. Share,. 1974. THEME Conf. Proc., p.511-35. Reed, T. B., and R. M. Lemner. 1973. Science 182: 1299. Russell, J. L., Jr.. aodJ.T. Porter. 1974. THEME Conf. Proc., p. S.lt.49. Science. 1974. 185:133 (l2Jsly(. Sharer, J. C., and J. B. Pangboen. 1974. THEME Conf.Proc., p.S12-29. Steinberg, M., F. J. Salaano, M. Belier, and B. Manosoita. 1973. USAEC Reps. BNL.17800 (April). Available NTIS. Sssitmndick, A. C. 1974. THEME Conf. Proc., p. 56-1. Synthetic Fuels Panel. 1972. Hydrogen and other synthetic fuels: A summary of the worh of the panel. Prepared for the Federal Council on Science and Technology R & D Goals Study. USAEC Rept. TID.26l36. Washington, D.C.: USGPO, p.41. Tantram, A. D. 5. 1974. Energy Policy. 2(1):55. U.S. Bureau of Mines. 1970. Mineral Facts and Problems. Bureau of Mines Bulletin 650. U.S. Dept. of the Interior. Valentine, R. C., L. E. Mortenson, and J. E. Cam. nahsn.1963.J.Biol.Chem.238(3(1141. von Bogdandy, L., H.-D. Panthe, and U. Phol. 1966.J. Metals 18:519. Waide, C. H., J. J. Reilly, and R. H. Wisooall. 1974. THEME Csnf. Proc., p.58-39. Wmntorf, R. H., and R E. Hasseman. 1974. Science 185:311. Wild, R. 1969. Chem. and Process Engn. 50:55 (Feb.). Williams, L. 0. 1973. Cryogenics 13(12):693. Wortberg, E. J. 1971. Thesis, Aaches Tech. Hoch- sobs),. (NSA Abstract No.27700, 15 Dec. 1973.) References Many of the aeticles referenced belos are from The Hydrogen Economy Miami Energy Confer- ence Proceedisgs (THEME), 18-20 March 1974, rdttrd by T. Nejat Veairogls and available feom The School of Continuing Studies, P.O. Bon PAGENO="1124" 1118 CRYOGENIC H2 AND NATIONAL ENERGY NEEDS 3, Hord Cryogenics Division Institute for Basic Standards National Bureau of Standards Boulder, Colorado 80302 Paper N-i Preprinted for the Cryogenic Engineering Conference Atlanta, Georgia August 8-10, 1973 PAGENO="1125" 1119 CRYOGENIC H2 AND NATIONAL ENERGY NEEDS J. Fiord Absl ract Our impending fossil fuel shortage is a clear challenge to the cryogenics industry and government to provide efficient and economical means of satisfying specific national fuel requirements. Large scale production of liquid hydrogen was stimulated by the U. S. space exploration program. Now, civilian demands for synthetic fuels beckon cryogenic hydrogen. National and world energy shortages are briefly summarized to demonstrate the relevance of synthetic fuels in satisfying future energy markets. A perspective of national energy needs, as they relate to cryogenic hydrogen fuel, is given. Hydrogen and alternate synthetic fuels are briefly reviewed and potential applications for cryogenic hydrogen are described. Technical research and development efforts, required to satisfy specific cur- rent and future national needs, are identified. The mecha- nism for implementation of synthetic fuels and the indistinct timetable for transition to these fuels are discussed, PAGENO="1126" 1120 CRYOGENIC H2 AND NATIONAL ENERGY NEEDS J. Hord INTRODUCTION Hydrogen, as a non-fossil synthetic fuel, is a prime candidate to satisfy many of our long-term fuel requirements. Specifically, cryogenic hydrogen offers significant advantages for many applications. The obj ec- five of this paper is to synthesize the voluminous and sometimes specula- tive literature, emphasize cryogenic hydrogen applications and appraise the prospects for cryogenic hydrogen in the rapidly expanding fuel market. To suggest that non-fossil hydrogen is a panacea to all of our energy problems is technically irresponsible and inexcusable. An abundant non- polluting energy source is required to mass-produce hydrogen from water. Thus, hydrogen is an energy-carrier (or fuel), not an energy source-- see figure 1. In this capacity hydrogen can fill certain vital needs in future energy conversion concepts. Conservation of energy resources, environ- mental compatibility, economy and convenience are essential criteria of the future- - some aspects of the `hydrogen economy' will conform and others will fail. As our energy shortage is real we must also conserve human resources. Proliferation of the literature with highly speculative engineering is self-defeating. In-depth technical and economic evaluations are now required to identify market potentials. The cryogenics industry has the technology and proven capability to shoulder its share of the burden. NATIONAL ENERGY NEEDS AND RESOURCES Needs and Resources. We refer here to energy needs rather than energy goals because national goals have not yet been defined. The enor- mous task of establishing national goals requires national leadershipt and will undoubtedly languish in obscurity until a federal energy management t Since this paper was written, Governor John A. Love of Colorado has been appointed to direct the White House Energy Policy Office. PAGENO="1127" 1121 ENERGY SOURCE ENERGY CARRIER ENERGY USER t t $ Foss~ Fuels Fossil Fuels ~ Gas and C~) Electńcity Fuels Synthc Hydrogen (fossil) SNG Methanol, etc. * Solar Electńcity Nuclear ( Hydrogen (nonfossil) Electńcfty Methanol, etc.-~ Industrial Commercial * Ge~herm~ Electricity Transportation Steam HoUsehold (~ Hydroelectuc * (Wind & Ocean) { Electncity ~. Hydrogen (nonfossil)-~ Electncfty-~- Natur~ Fuels OTHER ) _______ I ~ ,~ Electricity I Wood, Agdcultur~ Crops, ( Synthetic Fuels I Bislegicel Wastes, _________ L irasii, etc. SNG Ethanel * Categoricelly defined as geophysical energy sources. FIGURE 1. Energy-Fuel Relatioash~s PAGENO="1128" 1122 agency [1] is commissioned. Many authors, particularly n~ntechnical ones, consider the current energy shortage as a dilemma rather than a crisis. Irrespective of the terminology, the demand and stiortage are real. Interim solutions to this energy shortage consist of increased impor- tation of fluid fossil fuels, increased success in discovery of new domestic fossil fuel resources, coal gasification, and the use of high grade ore nuclear fission reactors. Forecasts indicate that our economically recoverable fos- sil fuel reserves will be depleted prior to 2100 A.D. High grade ore fission reactor power reserves are uncertain--one forecast [2] predicts that this energy source will be depleted of low-cost ores by the year 2000. Wind, tide, geothermal1 and other miscellaneous energy sources may help ease the strain on our fossil fuel reserves but are not expected to be ~j~r sources of energy. Long-term abundant energy sources may be narrowed down to breeder fission reactors, fusion reactors and solar power as illus- trated in figure 2. Breeder reactors could supply our country's energy needs for thousands of years while nuclear fusion rivals solar power as an energy source until the end of life on earth. The fast breeder reactor [7] is not expected to be operational for another 10 years and the controlled thermonuclear reactor (fusion) is expected [8] to take at least 25 years. Development of economical solar energy [9-11] is proceeding at an equally slow pace. All fission and fusion reactors present certain biological and environmental threats. The handling, disposal and safeguarding of waste radioactive materials from breeder reactors is quite a challenge, even for our advanced society. Tritium containment in fusion power plants appears surmountable, but only solar power emerges as an abundant non-polluting energy source with minimal threat to man. There are currently two major proposals for large-scale harvesting of solar energy--one proposes land-based solar radiation panels [12] and the 1 At this writing, the potential of geothermal energy is subject to considerable debate [3-6]. PAGENO="1129" Terawatt Years ENERGY DEMAND (1960-2000 A.D.) :***~ 140 100 LI] U.S. * World Reserves for 02 - 12 reaction estimated at 6800 1W-years. Note: All data plotted or extracted from C. Starr or M.K.Hubbert, Sci. Amer., 224(3): 36 (Sept. 1911). FIGURE 2. Estimated U.S. and World Energy Resources ENERGY SOURCE 102 `300 `1310 aoo 3000 - 108 1010 FOSSIL FUELS NUCLEAR (ordinary) NUCLEAR (breeder) NUCLEAR* (D2 - 02 Fusion) SOLAR RADIATION 106 I I Reserves 30000 300000 1012 at Double Current Cost 1.6 x I. 1.6 x 1010 2.8 x 1011 ~ (2% Depletion of 02 in Sea Waler) (1% Land Area, 10% Efficiency, Earth Life 1010 Years) PAGENO="1130" 1124 other expands on the age-old idea of DArsonval to use sc);:. ~ pow: [13-151. The latter idea uses the temperature difference o~ seawater sup- plied on a continuous basis by solar radiation to the oceans, to supply our energy needs. Solar energy concepts have always suffered, as have the electrical utilities, from the inability to effectively store energy. A con- venient means of storing energy is in the form of molecular hydrogen. Relevance of Non-Fo8sil Hydrogen. This man-made hydrogen, or syn- thetic fuel, could be mass-produced by thermochemical decomposition of water or by electrolysis of seawater- -the required heat and/or electricity being supplied by solar or nuclear power. Hydrogen could then be used as a synthetic fuel to satisfy various energy markets, e.g., household, com- mercial, industrial, and transportation needs. When all fossil fuels are gone, solar or nuclear power can thus be used to make hydrogen. Hydrogen could be produced continuously or in some cases during the intermittent off- peak hours for electricity consumption. Whether we use electricity or hydro- gen as the energy carrier depends on production and distribution costs, avail- ability of energy, environmental insult and the nature of the energy- consuming device. It is improbable that all future portable power and energy storage re- quirements can be met with either electricity or hydrogen alone. Fossil fuels and other synthetics will also compete in these markets for at least the next 50 years. In fifty years, the concept of electric-powered aircraft may be more tenable and storage of electrical energy in superconducting magnets [161 may be common practice; however, the technology required to produce and use hydrogen exists today. Hydrogen fuel is appealing because it offers convenient energy storage, portable power and reduced air pollution. The selective substitution of hydrogen for fossil fuels is an attractive partial solution to our fuel shortage; however, we still need to develop an abundant, non-polluting ene~gy source to produce the hydrogen. Solar power, using hydrogen as an energy storage media is an equally attractive solution to our energy-fuel crisis. Solar sea power is particularly attractive because PAGENO="1131" 1125 there is no need for man-made solar collectors; therefore, potentially cheaper and more reliable power may be produced without sacrificing large tracts of land. Minimal adverse environmental impact is antici- pated with solar sea plants. With certain technological advances, off- shore nuclear power plants [17] are also expected to be environmentally- compatible energy sources for the production of hydrogen (and/or electricity). The production of non-fossil hydrogen increases the burden on raw energy sources- - the penalty we pay for storing and packaging energy in a convenient form. From a pure conservation viewpoint we could argue that non-fossil hydrogen should be used only when a chemical form of energy is essential. But if we harness vast2 sources of energy and produce hydro- gen economically, and if environmental threat is within acceptable limits, extensive use of hydrogen is technically and morally warranted. In reality, the non-fossil hydrogen market will be limited by the cost of producing it from solar or nuclear power. CONSIDER SYNTHETIC FUELS Why Hydrogen? Although hydrogen is estimated to comprise 90 percent of the universe, it must be man-made as it does not occur abundantly as a gas on earth. Further, we must distinguish between fossil and non- fossil synthetic hydrogen as long as hydrogen is produced from coal. De- tailed comparisons of synthetic fuels are available in the literature [18-23]; leading candidates are hydrogen, methanol, ethanol, ammonia, hydrazine and synthetic natural gases (SNG). Fuels produced from farm [24] and biological wastes are of minor significance [25]. The SNG's are source-limited, ammonia and hydrazine are toxic, ethanol competes with food-crops and is expensive. Methanol is slightly toxic but emerges as the chief long-term competitor3 to non-fossil hydrogen. Methanol, natural gas, and SNG can compete with non- fossil hydrogen until fossil fuel reserves are depleted. Then the cost of methanol, synthesized from hydrogen-and-limestone [21] or hydrogen- and-CO2 from the air [18, 19], is expected to rise markedly. In the latter two processes 2 Available at anticipated use rates as long as earth will support life. ~ It appears that methanol will also compete [26] with LNG in the near future. PAGENO="1132" 1126 hydrogen holds a cost advantage because hydrogen is req'~ired to produce methanol. Hydrogen wins either way, whether it is usezi its pure form or is converted into methanol. Fossil hydrogen- -produc~d £rom coal [27, 28], shale or crude oil--is expected to cost less than non-fossil hydrogen until fossil fuel prices at least double (or until non-fossil hydrogen produc- tion costs are halved). Physical State. The application dictates the proper physical form of hydrogen. Room temperature hydrogen gas is a candidate fuel in all sec- tors 118, 19, 28-30] of the energy market. It is a potential competitor in all current and future markets served by natural gas and electricity. Bulk quantities of hydrogen are used by the oil refineries and in the production of ammonia and methanol. Hydrogen is also used in the electronics, glass- making, food, pharmaceutical, and metalworking industries. The arguments for use of gaseous hydrogen in transportation are less convincing than those for residential, commercial and industrial uses. In gaseous form, hydro- gen must compete with electricity, natural gas and SNG. Cryogenic hydro- gen is attractive as a transportation fuel ~21, 22, 30-36], and has certain potential advantages in hydrogen-electric utility systems [13, 37-39]. In gen- erating peak electrical power the competing fuels are LNG, LSNG,4 and methanol. Chief competitors in transportation are electricity, LNG, LSNG, and methanol. `Thermodynamic thrift' will surely be sacrificed for conve- nience (and perhaps economy) in many of these applications. Cryogenic hydrogen is unexcelled in performance as an aerospace fuel. Recent debates 140] accentuate the importance of hydrogen physical form and the competition between the gas and electric industries. CRYOGENIC HYDROGEN Production. Recent publications [41, 42] indicate that production costs for electrical power will be about 12 mills/kW-hr within 5 years. Cur- rent (unpublished) estimates indicate that production costs will soar to 15 mills/kW-hr by 1981. Using the lower unit cost for energy (12 mills/kW-hr) ~ Liquefied Synthetic Natural Gas. PAGENO="1133" 1127 and extrapolating water electrolysis cost data [18] the projected cost of electrolytic hydrogen is 0.21 to 0.28 $/pound. This cost could be re- duced by lower cost electricity [13] or by innovative improvements [43, 44] in thermochemical decomposition [45] of water. The high temperature gas-cooled reactor (HTGR), as described by Quade [44] is frequently suggested as an interim source of process heat. Cost credits for by-product oxygen will be negligibly small unless new vora- cious markets are identified. Liquefaction, etc. The cost to liquefy/slush/solidify hydrogen was determined from the data of Hallett [46] and Strobridge [47] under the following terms: Plant output of 250 to 2500 tons/day, operation 350 days/annum, fixed charge rate of 12 percent on capital investment, plant efficiency @ 40 percent of Carnot, 12 rnills/kW-hr for energy, integral lique- faction-slush facility, liquid storage capacity of 2 days output, and 10 K refrigeration for solidification of hydrogen at 13 K. Liquefaction costs range from 0.072 to 0.098 $/pound of hydrogen. Producing 50 percent solid-fraction slush increases the liquefaction cost by about 24 percent. Solid hydrogen can be produced from 50 percent solid slush for an addi- tional 8 percent of liquefaction cost- - a total increase of about 32 percent over liquefaction cost. Calculations indicate that solid hydrogen can be produced more economically from NBP liquid: approximately 27 percent increase in liquefaction cost. From these estimates the total cost of producing liquid hydrogen is about 0.30 to 0.37 $/pound of hydrogen--slush can be produced for an additional 0.02 $/pound. Using the appropriate bulk densities and lower heating values for gasoline and hydrogen the foregoing liquid prices trans- late into equivalent costs of 0. 63 to 0. 78 $/gallon for gasoline (excluding taxes, distribution costs, and assuming identical thermal conversion efficiencies for gasoline and hydrogen). This energy cost may also be expressed as 5.33 to 6.98 $/l06 Btuor 18 to 24 mills/kW-hr. Escalating costs of fossil fuels could soon offset this seemingly exorbitant price of non-fos sil hydrogen. PAGENO="1134" 1128 ________ In the foregoing estimates storage costs of liquid hydrogen were nearly negligible; however, larger storage capacity II drive hydro- gen prices up. Installed costs for liquid hydrogen storage range from 1.00 to 2. 00 $/gallon for perlite insulated dewars of less than io6 gallon capa- city. Hallett [46] estimates that perlite insulated dewars, larger than 106 gallon capacity, can be constructed for 0. 60 $/gallon and urethane foam insulated tanks would cost about 0.22 to 0. 60 $/gallon. Metal hydrides are also under investigation [29] as hydrogen reservoirs. Most of the advantages [29] and disadvantages[22] of these hydrides have been disclosed. Though frequently touted for containment of hydrogen in the transportation sector, use of these hydrides in stationary storage applications is more appealing. Liquefaction and storage costs [37, 46] for hydrogen are much higher than those for LNG; thus, the price of natural gas can exceed that of hydrogen gas and LNG will still be competitive with liquid hydrogen. Unfortunately, the life expectancy of natural gas is rather short. Transmission. The concept of transmitting electrical power and cryogenic hydrogen through the same transmission line [48] is fascinating and highly futuristic. It is certainly not obvious at this time that super- conducting or cryogen-cooled high-conducting transmission lines will ever be economical. Perhaps the multi-purpose transmission line will permit low-temperature conductors to scale this hurdle. The total cost of transferring liquid hydrogen through long pipelines is not well known; however, the rule-of-thumb cost for vacuum-insulated piping is about $15 to $20 per lineal foot for each inch of inner line diameter. Liquid hydrogen is currently shipped by highway and rail [37, 49] and could easily supply packaged power to remote sites, e. g., hamlets, mountain cabins, etc. Applications in Utilities. Hydrogen and electricity are not always competitive--in mixed-utility and electricity peak-shaving concepts they are complementary. Liquid hydrogen has been proposed for peak-shaving operations [39] and in mixed utilities [38] where hydrogen is the chief PAGENO="1135" 1129 energy carrier. Preliminary calculations reflect low overall energy con.. version efficiencies for these systems- -unacceptably low if limited energy sources are used; however, the availability of abundant energy sources makes these inefficiencies more palatable. In the latter case our major concern would focus on environmental compatibility, cost and convenience. Then, if non-fossil hydrogen can be economically produced the cost of liquefaction is more readily borne and cryogenic hydrogen is tenable- - the aforementioned utility applications and a variety of others are possible. Development of solar sea plants should favor the cryogenic form of hydro- gen for transmitting energy from remote ocean sites to population centers. Similar, though weaker, arguments may be advanced for liquefying hydrogen produced with offshore nuclear reactors. In any case, cheap production costs add incentive to liquefy. Applications in Transportation. Perhaps the most promising market for cryogenic hydrogen is in the transportation area. About 25 percent of the energy consumed in this nation is allocated to the transportation sector and significant opportunities for conservation have been identified [50]. The most efficient [50-53] means of transportation are by train, bus, plane and auto in about that order.5 Hydrogen-air turbine driven trains, trucks and busses are a distinct possibility [36]. Such institutional vehicles are not so volume/weight restricted and cryogenic hydrogen offers signifi- cant potential. Electrical propulsion of these vehicles (and autos) by hydro- gen-air fuel cells [54, 55] requires further technological development-- again onboard cryogenic storage is attractive. Liquid hydrogen may find its maximum near-future potential in the aircraft industry. Studies [34, 35] indicate that cryogenic hydrogen is essential for aerodynamic cooling of hypersonic aircraft and highly desir- able for supersonic airplanes. Interest in the use of liquid hydrogen in ~ Depends on definition of `efficiency' and whether freight or passengers are being transported (bicycles and pipelines are also highly efficient). PAGENO="1136" 1130 subsonic [56, 57] aircraft has also been renewed [58]. All three classes of hydrogen-fueled aircraft should show substantial performance gains (range, engine life, etc. ). Impetus from the federal government will be required to initiate this fueling trend. An evaluation of climatic impact [59]-- due to hydrogen-fueled aircraft- -is needed. Slush hydrogen also offers some advantages as an aircraft fuel: 50 percent solid slush provides an 18 percent increase in heat capacity and a 15 percent increase in bulk density when compared to NBP liquid hydro- gen. Handling [60] of slush hydrogen is difficult and the use of helium pressurant is unacceptable in commercial applications. Total helium re- sources [61] in the U.S. are about 180 x l0~ standard cubic feet. This reserve would last but a few years if helium were used to service an air- craft system [46] requiring 8000 tons/day of slush hydrogen. Thus, new techniques for handling slush with hydrogen pressurant may be required, e.g., the innovative use of pumps, hydrogen gas, honeycomb antislosh baffles and ullage liquid-vapor screen separators. The personal auto is the major consumer [so] of energy in the trans- portation field. Powered by the highly-developed internal combustion en- gine, it is also a vehicle with stringent volume/weight restrictions. For this reason alone, liquid hydrogen is a somewhat marginal [22] fuel as are metal hydrides- - clean burning hydrocarbons are probably better suited for this job, see figure 3. Development of suitable hydrogen-air fuel cell propulsion units[55] could drastically reduce hydrogen weight and volume requirements. The safety aspects of hydrogen-fueled autos are perplexing. Gasoline is safer than hydrogen for autos but hydrogen is not too hazardous to use. Safety considerations are different for autos, aircraft, trains, etc. Hydro- gen may well be as safe as gasoline or kerosene with the carefully con- trolled environment, logistics and skilled technicians available to aircraft and institutional vehicles. With autos, we are dealing with a much larger PAGENO="1137" 1131 6 6 5.65 CITE] (FneI + Tauk) Volume Ratio* - ____ [Fuel + Tank) Wejkt Ratio' ~~~1 ~ Relative to gasoline for 4.04 4.23 ~ eqisvalent energy storage. 3 2.85 3 2.651 2 2 -_ IT1 AMMONIA METAL LIGUID (NH3) HYDRIDE HYDROGEN (3) (4) (2) (1) Ordinary auto steel tanks. (2) Multilayer & vacuum insidated, 55 spherical dewars (10 atm.). [3) Steel spherical t~*s (30 atm.). [4) Magnesium-Nickel hydride (Ref. (29) ): Insulated SS spherical tanks (600 K & 10 atm.), 60 % packing factor (30 % porosity and 10 % voids for heat exchaoger) ; excludes start t~*, valves, filter, etc. NOTE: Less practinal hydr~en fuel systems are deliberately omitted from this figure [e.g. con~ressed H2 gas and the le~uid H2 . liquid 02 system). Also, ullage volumes ~e neglected for all fuels [5 to 10 % volume expansion is required for most fuels). FIGURE 3. Estimated [Fuel + T~*) volume and weight ratios for candidate fuels. The ratios are based upse the low heat of combustion for each fuel and are applicable for comparison with gasoline tanks of 12.5 to 25 gallon capacity. GASOIJNE METHANOL LNG (C8 H18) [CH3 OH) (~-CH4) (1) (1) [2) 62-332 0 - 76 - 72 PAGENO="1138" 1132 number of vehicles and unskilled people (owners). To debate the safety pros and cons of hydrogen vs gasoline is meaningless withouL specifying accident criteria [62]. We can draw general comparisons on the basis of fire hazard, fire damage, explosive hazard and explosive damage. Gaso- line loses in but one category: fire damage. It is not clear what fraction of the auto industry liquid hydrogen could or should claim. A go-slow policy seems likely in this area as natural and alternate synthetic fuels are available. Large ships might also find liquid hydrogen an attractive fuel. Ex- tension of LNG shipbuildinge and insulation technology to accommodate liquid hydrogen looks technically feasible but challenging. LNG tankers are currently burning in-transit boil-off gas to help propel the ship; ex- clusive use of crude oil for ship propulsion and onboard reliquefaction of boil-off natural gas are under consideration. Boil-off and reliquefac- tion problems are amplified when transporting liquid hydrogen. There are no adverse environmental effects from oceanic spillage of liquid hydrogen and recovery of onboard combustion products would provide abundant ship- board utility water. Shipment of liquid hydrogen may be the best way to transport energy from solar sea plants. Development of these plants could initiate a liquid hydrogen shipping industry. Small volume/weight limited portable power units, e.g., motorbikes, motorboats, lawnmowers, etc., are likely to continue operating on gasoline and eventually switch to methanol. Aerostpace. Liquid hydrogen is the `standard' fuel and slush [60] and solid [64] hydrogen are candidates for future deep-space probes. In this limited application the additional expense for slush or solid is immaterial and the frugal use of helium gas is justified. The NASA has scheduled the Space Shuttle for 60 flights/year, carrying 14 x io6 pounds/year of liquid hydrogen into space- - a mere dribble compared to potential aircraft 6 Transportation of natural gas by airship has also been suggested [63]. PAGENO="1139" 1133 consumption7 rates. The latter is also about double the 1968 national production [65] of 11 x 1O9 pounds of hydrogen. RESEARCH EFFORT REQUIRED Opportunities for technological improvements are abundant. Develop- ment of solar and nuclear energy sources and coal gasification techniques are essential. The minor energy sources, wind, oceans (tide, waves, cur- rents), geothermal, etc., should not be neglected. An inexpensive and environmentally- compatible method for producing non-fos sil hydrogen is needed. Application-oriented issue studies are needed to evaluate alternate fossil and non-fossil synthetic fuels. Detailed studies are needed to evaluate the benefits of cryogenic hydro- gen in proposed applications- - currently concentrated on mixed utilities, peak-shaving and transportation. In the well-developed cryogenic field we can strive for higher efficiencies and lower costs in liquefaction, trans- mission, portable and large-scale stationary storage. Strong, light-weight structural materials and improved insulation materials for cryogenic service are sought. High efficiency energy conversion techniques are needed, e.g., the development of H2-air and H2-02 fuel cells and gas turbines as well as hydrogen-fueled catalytic heaters. Fueling of all classes of aircraft, institutional vehicles and autos with liquid hydrogen should be meticulously analyzed and performance-evaluated where (and when) it is feasible. Hydro- gen-powered ships and transoceanic transport of liquid hydrogen should be examined. Research efforts on multi-purpose hydrogen-electric trans- mission cables and superconducting energy storage systems can be intensified. New markets for by-product oxygen should be identified. Thermo- physical properties of mixtures (H2 + CH4 from coal) are needed and applica- tions for LSNG should be investigated. Data on hydrogen embrittlement of steels should be compiled and analyzed and further research performed- - particularly as it relates to transmission of hydrogen and hydrogen-hydro- carbon mixtures through existing natural gas piping networks. Additional 7 . 9 Aircraft consumed the equivalent of 24 x 10 pounds of hydrogen in 1970. PAGENO="1140" 1134 work on metal hydride storage seems worthwhiJe and cc~a~Jatton a.i~ analysis of hydrogen safety data shrild ~c--~.nue. Substitution of hydrogen for natural gas in pipe~n: raisas odorization, contaminant detection and leakage problems. Leakcge is also a factar for consideration in cryogenic hydrogen systems. !t ha~ bccn chown [b61 that leakage is inversely proportional to the square root of the density or to the absolute viscosity of the fluid. Thus, volumetric leakage flow of hydro- gen gas will be 1. 25 (viscous flow) to 3 times as large as methane leakage (at the same temperature and pressure). Economics, environmental impact and energy conservatica ~:aar~i be overemphasized in performance of these studies. TRANSITION TO SYNTHETIC FUELS Government leadership and funding is required to accelerate the transition to synthetics. A national Energy Agency, national goals and cornmittments are needed. Increased imports result in higher fuel prices, potential threat to national security and staggering economic deficits [67]. With universities and industry cooperating with government on an intensive national effort synthetic fuels could soon be implemented. A similar national effort placed man on the moon- - a national fuels effort offers even greater rewards. Under current circumstances any timetable for transition to synthetic fuels must expose personal bias. The time schedule depends upon 1) the resourcefulness of government and industry leaders, 2) interim solutions, e.g., practiced conservation and increased success in discovery of domestic fossil fuels, 3) the price paid by the consumer for enforcement [681 of environmental control standards, i.e., the future cost of synthetics vs fossil fuels and, 4) technological developments in the fields of solar power, nuclear fusion, breeder fission, shale oil and coal gasification/liquefaction. SNGs from coal [27, 69] should be available in quantity by 1985--their earlier use being limited by competition with domestic natural gas, imported LNG and by capital investment. Commercial development [70] of shale oil, tar sands and cpal liquefaction should proceed at about the same pace. PAGENO="1141" 1135 Non-fossil hydrogen will not help alleviate our fuel shortage until inexpensive, abundant energy sources are developed. Currently, the only prospect is for operational breeder reactors by the mid-eighties. Thus, it appears that a major non-fossil hydrogen market could not develop prior to 1990. In the interim, fossil hydrogen from coal could help pave the way for future quantity usage of non-fossil hydrogen. With increased public awareness, appropriate funding and management, frank technical appraisals and application of the vast talents and ingenuity of American scientists this time schedule may be shortened. A challenge is issued to the cryogenics industry to develop competitive means of satisfying specific national fuel requirements with LNG, LSNG and ultimately with liquid hydrogen. CONCLUDING REMARKS The scientific and engineering disciplines for large-scale liquefaction, storage and handling of hydrogen evolved through our military and space efforts. We are fortunate to have over 20 years of experience with liquid hydrogen--an appealing candidate in many future fuel concepts. Modifica- tions of existing technology to tailor-fit new specific fuel requirements are well within the capabilities of the cryogenics industry. So equipped, this industry is in a strong position to meet its responsibilities and simultaneously has the opportunity to help solve national fuel needs through cryogenic technology. PAGENO="1142" 1136 RE FERENCES 1. D. A. Dreyfus, Federal Energy Organization," Staff Analysis pursuant to Sen. Res. 45, Serial No. 93-6 (92-41), Wash. , D. C. (1973). 2. M. K. Hubbert, Sd. Amer., 224(3):68 (1971). 3. D. W. Brown, M. C. Smith, and R. M. Potter, `A New Method For Extracting Energy From Dry' Geothermal Reservoirs," Los Alamos preprint, LA-DC-72-1157, Los Alamos, N.M. (1972). 4. A. L. Austin, G. H. Higgins, and J. H. Howard, "The Total Flow Concept For Recovery of Energy From Geothermal Hot Brine Deposits," Rept. 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McDonald, "Magnetic Energy Storage and Its Application in Electric Power Systems," submitted to: IEEE 1973 Internat. Cony, at New York (Mar. 1973). 17. G. D. Friedlander, IEEE Spectrum, 10(2):44 (1973). PAGENO="1143" 1137 18. J. W. Michel, et al., "Hydrogen and Other Nonfossil Synthetic Fuels,' USAEC, to be published (1972). 19~ D. P. Gregory, D. Y. C. Ng, and G. M. Long, in: Electrochemistry of Cleaner Environments, Chap. 8, Plenum Press, New York (1972), p. 226. 20. T, D. Weikel, "Ground Support Equipment; Low Pollutant Fuels," Rept. NAEC-GSED-59 (1972). 21. 0. V. Day, Futures:331 (Dec. 1972). 22. A. L. Austin, "A Survey of Hydrogen's Potential as a Vehicular Fuel," Rept. UCRL-51228, Livermore, Calif. (1972). 23. F. Bacon and T. Fry, New Scientist: 285 (Aug. 1972). 24. K. Kiang, H. F. Feldmann, and P. M. Yavorsky, "Hydrogasification of Cattle Manure to Pipeline Gas," presented at the 165th Nat. Meeting, Amer. Chem. Soc., Dallas, Tex. (Apr. 1973). 25. L. L. 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D. Escher, `On the Higher Energy Form of Water (H20*) in Automotive Vehicle Advanced Power Systems," Proc. of 7th IECEC:1392 (1972). 33. L. W. Jones, "Liquid Hydrooen As A Fuel for Motor Vehicles: A Comparison with Other Systems," Proc. of 7th IECEC:1364 (1972). 34. R. D. Witcofski, `Potentials and Problems of Hydrogen Fueled Supersonic and Hypersonic Aircraft," Proc. of 7th IECEC:1349 (1972). 35. A. A. duPont, in: Advances in Cryogenic Engineering, Vol. 12, Plenum Press, New York (1966), p. 1. 36. Washington Science Trends, 30(8):45 (May 28, 1973). 37. 3. R. Bartlit, F. J. Edeskuty, and K. D. Williamson, Jr., "Experience in Handling, Transport and Storage of Liquid Hydrogen - The Recyclable Fuel," Proc. of 7th IECEC:1312 (1972). 38. E. C. Tanner and R. A. Huse, "A Hydrogen-Electric Utility System with Particular Reference to Fusion as the Energy Source," Proc. of 7th IECEC:1323 (1972). 39. D. P. Gregory, Sc Amer., 228(l):13 (1973). 40. 3. H. ~hiles III, Sci. 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"The Potential For Energy Conservation," A Staff Study, Office of Emergency Preparedness, Wash. , D. C. (Oct. 1972). 51. C. W. Savery, Traffic Quarterly:485 (Oct. 1972). 52. W. P. Goss and 3. G. McGowan, Transportation, !(3):265 (1972). 53. E. Hirst, "Energy Consumption For Transportation in the U. S. ," Rept. ORNL-NSF-EP-15, Oak Ridge, Tenn, (Mar. 1972). 54. Y. Breelle, 3. Cheron, and A. Grehier, "Autonomous Hydrogen / Air Fuel Cell for Long-Life Missions," Proc. of 7th IECEC:1 (1972). 55. K. V. Kordesch, Journ. of the Electrochem. Soc., 118 (5): 812 (May 1971). 56. R. C. Muiready, in: Technology and Uses of Liquid Hydrogen, Chap. s; Macmillan Co., New York (l964),p. 149. 57. "Hydrogen for Turbojet and Ramjet Powered Flight," Staff Rept. NACA RM E57D23 (Apr. 1957). 58. R. D. Witcofski, Langley Res, Center, NASA, personal communication. 59. A. Goldburg, Astro. and Aero. ,10(12):56 (1972). 60. C. Sindt, Cryogenics:372 (Oct. 1970). 61. W. M. Deaton and P. V. Mullins, in: Technology of Liquid Helium, Chap. 1, 13. 5. Gov. Print. Office, Wash., D. C. (1968), p. 4. 62. J. Hord, "Explosion Criteria for Liquid Hydrogen Test Facilities," unpublished NBS Report (Feb. 1972). PAGENO="1146" 1140 63. M. H. Sonstegaard, Mech. Engr., 95(6):19 (1973). 64. J. Hord, `Solid Hydrogen as a Space Storable Propellant- -A Preliminary Study," Unpublished NBS Rept. (Mar. 1972). 65. P. Meadows and J. A. DeCarlo, in: Mineral Facts and Problems, Bur. of Mines Bulletin 650, Wash., D. C. (1970), p. 97. 66. J. Hord, "Correlations for Predicting Leakage Through Closed Valves," NBS TN 355(1967). 67. P. G. Peterson, "Energy Research- -The Key to Our Long Range Energy Future," presented to the 55th Anniversary Convention of the Nat. Coal Assoc. , Wash., D. C. (June 1972). 68. N. deNevers, Sci. Amer., 228(6):l4 (1973). 69. S. A. Bresler and J. D. Ireland, Chem. Engr. :94 (Oct. 16, 1972). 70. W. D. Trammel, Chem. Engr.,:68 (Apr. 30, 1973). 71. R. D. McCarty and L. A. Weber, "Thermophysical Properties of Parahydrogen from the Freezing Liquid Line to 5000 R for Pressures to 10,000 Psia," NBS TN 617 (Apr. 1972). Pertinent References Not Cited in Text 72. J. G. McLean and W. B. Davis, "Guide to National Petroleum Council Report on United States Energy Outlook," Nat. Petroleum Council, 1625 K. St. N. W., Wash. D. C. (Dec. 1972). 73. A. L. Austin, B. Rubin, and G. C. Werth, "Energy:Uses, Sources, Issues," Rept. UCRL-5l221, Livermore, Calif. (1972). 74. M. McCormack, "Energy Research and Development, "Rept. of the Task Force on Energy, 92nd Congr., Serial EE, Wash., D. C. (Dec. 1972). 75. "National Gas Supply and Demand 1971-1990," FPC S-2l8, Staff Report No. 2, Bur. of Nat. Gas, Federal Power Commission, Wash., D. C. (Feb. 1972). 76. V. D. Arp, A. F. Clark, T. M. Flynn, "Some Applications of Cryogenics to High Speed Ground Transportation," NES TN 635 (Feb. 1973). PAGENO="1147" 1141 77. W. Berry, et al., "A Fuel Conservation Study for Transport Aircraft Utilizing Advanced Technology and Hydrogen Fuel," NASA CR-ll2204 (Nov. 1972). 78. B. M. Abrahim and F. Schreiner, Science, l80(4089):959 (June 1973). 79. "An Assessment of Solar Energy as a National Energy Resource, H prepared by the NSF/NASA Solar Energy Panel, Dept~ of Mech. Engineering, University of Maryland, College Park, Md. (Dec. 1972). 80. 5. Weiss, "The Use of Hydrogen for Aircraft Propulsion in View of the Fuel Crisis", NASA TMX-68242 (Mar.1973). 81. The Energy Crisis, edited by R. S. Lewis and B. I. Spinrad, Sci. and Public Affairs, The Bulletin of the Atomic Sci. , 1020-24 E. 58th St. Chicago, Ill. 60637 (July 1972). PAGENO="1148" 1142 RESEARCH OPPORTUNITIES IN CRYOGENIC HYDROGEN-ENERGY SYSTEMS J. Hord Cryogenics Division Institute for Basic Standards National Bureau of Standards Boulder, Colorado 80302 Preprinted for the Hydrogen Energy Fundamentals Symposium Course University of Miami Coral Gables, Florida 33124 March 1975 PAGENO="1149" 1143 RESEARCH OPPORTUNITIES IN CRYOGENIC HYDROGEN-ENERGY SYSTEMS J. Hord Cryogenics Division Institute for Basic Standards National Bureau of Standards Boulder, Colorado 80302 USA Abs tract As liquid hydrogen pervades the commercial fuel market, new and improved products and technologies will be needed. To meet these demands appropriate research and development (R&D) must be performed on hydrogen fuel systems. Candidate markets for cryogenic hydrogen- energy systems are reviewed and discussed, and associated R&D needs are outlined herein. A wide variety of cryogenic R&D opportunities exist. Keywords: Cryogenic; energy; hydrogen; research and development. PAGENO="1150" 1144 1.0 INTR0DUCTIP~ Hydrogen is clearly a contender for the synthetic fuel market of the future -- only the time scale for implementation of this fuel is uncertain. If hydrogen can be economically produced from coal or water within the next decade we can expect significant changes in current modes of distributin~g marketable energy, and hydrogen fuel research will have a major impact on dispensation of this energy. A strong effort is needed to adapt space-age hydrogen technology to commercial use of hydrogen fuel. This substantial technology is also worthy of improvements that may hasten acceptance of hydrogen as a major commercial fuel. Research and development (R&D) targets are identified herein, with emphasis on the cryogenic aspects of hydrogen fuel. The application dictates the most suitable physical form of the fuel in the fuel market and cryogenic hydrogen is a contender in many potential fuel systems. A summary report on selected hydrogen-fuel topics was recently issued[ll; it illustrates some of the economic and technical incentives for performing the research highlighted in this paper. The summary document was prepared to identify cost and technical barriers to the commercial use of hydrogen fuel and is the foundation of many of the views advanced here. 2.0 CANDIDATE MARKETS AND R&D NEEDS Liquid hydrogen is not currently cost competitive [1) with alternate fuels in most of the major portable fuel markets. However, we must be continuously aware that fossil fuel prices are rapidly escalating, stringent pollution controls are being enforced and hydrogen-energy systems can be improved (increased efficiency of production, liquefaction, and combustion of hydrogen). These com- bined cost-influencing factors could permit liquid hydrogen to hurdle the cost barrier much sooner than any of us realize. Appropriate R&D efforts will result in improved hydrogen technology, greater economic viability, and conservation of our energy resources. To determine specific R&D needs for cryogenic hydrogen-energy systems, the markets must first be identified and then R&D efforts anticipated until the markets are actually established. Once the market is established we must provide for production, storage and distribution of liquid hydrogen in an efficient, fair and safe manner, and additional research requirements will undoubtedly surface. The next three sections of this paper address these topics. PAGENO="1151" 1145 2.1 The Cryogenic Hydrogen Market A brief state-of-the-art review of liquid hydrogen applications seems appropriate prior to a discussion of specific R&D needs. There is no substitute for hydrogen in a wide variety of pro- lific industrial processes (e.g., in producing ammonia and methanol, in hydrotreating and hydrocracking of ~etroleum, in manufacturing drugs, processing metals and hydrogenating foods). Large scale coal liquefaction and/or shale oil processing will require large quantities of hydrogen. Cryogenic hydrogen is not likely to be used in these applications unless liquefaction or cryopurification is required.to meet hydrogen purity requirements (as in some current processes). Hydrogen appears technically feasible and may be econonically attractive for transoceanic shipments of energy and in certain integrated gas-electric utilities [2,3]. In the integrated gas- electric utility concept, liquid hydrogen may be produced to store solar or off-peak electrical energy to meet peak or seasonal gas- electric utility demands. This concept can also be expanded to include the production of liquid hydrogen at sea-based solar or nuclear power plants (with ocean tanker transport to metropolitan centers) for integrated utility apPlications. Liquid hydrogen appears to be a strong competitor as an over-the-sea energy carrier, marginal [4] or noncompetitive [5] in electrical utility peaking applications, and competitive [2] in solar-hydrogen energy storage concepts. Subcooled liquid or liquid-solid hydrogen slurries (slush) may ultimately find some limited use as a coolant for superconducting [6] or cryoresistive power transmission lines. Liquid hydrogen may also find some limited use as a fuel for remote hamlets. The most promising application for cryogenic hydrogen lies in the field of transportation. The advantages and disadvantages of liquid hydrogen as an automotive fuel are summarized in the litera- ture [7-9]; however, liquid hydrogen is not y~ cost competitive with alternate fossil fuels in automotive applications [9]. The use of liquid hydrogen in aircraft has also been neatly summarized in the literature [10-12]. Economic comparisons are more difficult to assess in the aircraft application but Johnson [13] asserts that liquid hydrogen could be economically competitive with kerosene in the near future. The feasibility of using liquid hydrogen as a fuel for Naval vehicles is currently under study [14]. Liquid hydrogen is the accepted fuel of the aerospace industry and cost is not a barrier to its use. Thus, the major liquid hydrogen markets have been identified and consist primarily of potential applications in energy storage, energy shipment, integrated utilities and transportation. Potential PAGENO="1152" 1146 minor cryogenic hydrogen markets are: 1) subcooled liquid and/or slush hydrogen for superconducting or cryoresistive power applica- tions and the aerospace industry, 2) industrial processes requiring high purity hydrogen gas and 3) liquid hydrogen for rural utility applications. 2.2 Market Competition for Cryogenic Hydrogen In all anticipated applications of cryogenic hydrogen, the primary near-term competitors are fossil fuels and coal-derived synthetics (liquefied synthetic natural gas and liquid methanol). Hydrogen, in any physical form, is not ~ cost competitive in most of these appli- cations; therefore, only long-tern (post economical-fossil-fuel era) cryogenic hydrogen markets are considered here. In the energy storage and electrical utility fields the primary long-term competitors of liquid hydrogen are metallic hydrides [3,5,15,161, batteries [17-201, superconducting magnets [21-221, flywheels [231, compressed air and liquid air [241, and pumped-hydro- electric systems. The latter is no longer considered a viable alternative in most geographical locales. Liquid hydrogen and metallic hydrides are competitors in the integrated gas-electric utility concept [2-5,16]. Differences of opinion exist in this area but it appears that metallic hydrides currently hold an economic advantage. Bear in mind though, that liquid hydrogen production and storage costs are well documented and actual hydride costs are not yet known. Liquid hydrogen and metallic hydrides may ultimately serve the utilities industry in different capacities: Energy produced at sea may be imported in the form of liquid hydrogen and off-peak electrical energy may be stored in metallic hydrides. The economics of shipping hydrogen overseas is not yet clearly defined. Likewise, the cost of producing hydrogen at sea must be estimated. Zener [25] has projected low-cost energy from solar sea power plants. Delivering this energy from sea-to-shore in the form of hydrogen is no small task. As shown in the next section, it appears that the most economical way of transmitting hydrogen across the ocean is to liquefy and ship it in ocean-tankers. Gas pipelines are the most economical means of transmitting hydrogen over land. In the transportation field, liquid hydrogen is technically feasible as an automotive fuel [7-9], believed [10,11] to be a superior aircraft fuel, and is being evaluated in marine [141 applications. Liquid hydrogen offers significant weight and range advantages and thus holds a favorable position in the latter two applications; however, metal hydrides and electrical systems may compete for the automotive fuel market. PAGENO="1153" 1147 2.3 R&D Needs for the Production, Storage, and Distribution of Cryogenic Hydrogen Although easily identified, cryogenic hydrogen markets will not be easily established. Economic, social, and institutional barriers [12] must be overcome before hydrogen can become a major commercial fuel. While hydrogen is abundantly available [26, 27], the produc- tion and liquefaction of hydrogen are energy intensive processes requiring large capital outlays. Thus, to achieve lower cost hydrogen fuel we must improve hydrogen-energy system efficiencies. Consider- *able R&D efforts currently are being exerted to 1) produce gaseous hydrogen more economically via electrolysis and thermochemical techniques, 2) increase the efficiency of hydrogen liquefaction plants by using advanced liquefaction cycles that incorporate improved com- pressors, dry and wet expanders and possibly expansion ejectors, 3) recover liquefaction energy, and 4) improve the efficiency of energy conversion processes. A portion of the liquefaction energy may be recovered [27] by pumping the liquid to a high pressure, vaporizing and heating it to ambient temperature, and isothermally expanding the gas to near- ambient pressure. Work is extracted from the expansion device. The heat required in this recovery technique can be supplied by precool- ing air for a companion air separation plant. Enough oxygen can be obtained in this fashion to provide nearly stoichiometric combustion with the hydrogen being vaporized. Thus, increased combustion efficiencies may also be possible. Higher conversion efficiencies with fuel cells, MHD, gas turbines, catalytic converters, etc., will help establish the hydrogen market (gaseous and liquid). The air separation plants, if used in hydrogen-liquefaction- energy recovery systems, offer potential by-product credits in the form of helium and rare gases (neon, krypton, xenon, etc.) recovered from the atmosphere. Assuming that a future market exists for liquid hydrogen we must also dispense the fuel in an efficient, fair and safe manner. The most economical method [28] of delivering liquid hydrogen to the customer is dependent upon transmission distance, cost and avail- ability of water and electricity, accessibility of waterways and railroads, etc. Truck delivery is believed [28] to be the most practical and versatile means of supplying liquid hydrogen to users within a 100 km radius of the electrical power plant (used for electrolysis of water). Railroad delivery is attractive for trans- mission distances of 1000 to 2000 km and liquid-carrying ocean- tankers are most promising for transmission of hydrogen across the ocean. If all of the liquid hydrogen is to be used at a single installation, such as an airport, a gas pipeline (with a parallel electrical transmission line to power the liquefier) is the best 62-332 0 - 76 - 73 PAGENO="1154" 1148 choice for all overland transmission distances considered. As various liquid hydrogen markets emerge, more R&D effort will be required to define the optimum delivery systems. Cost data for overseas energy shipments are rather poorly defined. The placement of an insulated underwater pipeline for transmission of liquid hydrogen is considered impractical. Similarly, underwater superconducting cables are considered impractical. Two candidate methods for delivering energy are: 1) to ship liquid hydrogen in insulated ocean tankers and 2) to pump high pressure (135 atm @ 20°C) hydrogen gas through underwater pipelines. As no such ships exist, we can only estimate the cost of this operation; however, shipping costs for liquefied natural gas are known and provide a benchmark for this estimate. 9Using a shipping distance of 1600 km and a delivery rate of 2.3 x 10 kg/year of hydrogen (suffi- cient to supply New York City electrical demands), Simdt [28~ estimates liquid shipping costs to be about one-fourth the cost of gas transmission. This reduced shipping cost more than offsets the increased cost of liquefying the high pressure hydrogen gas. Thus, it appears that liquefaction and ocean-tankers are less expensive means of transmitting energy via hydrogen to metropolitan centers. Underwater gas transmission lines may be more competitive over shorter distances and should be much less competitive in longer lines. Longer pipelines would require ocean-based compressor stations, adding to the cost of gas transmission. The cost of transmitting stoichiometric quantities of gaseous oxygen 1600 km by underwater pipeline was found to be prohibitive because two oxygen pipelines are required for each hydrogen pipeline. The oxygen pipeline diameters and operating pressures must be identical to the hydrogen pipeline in order to transmit 8 kg of oxygen per kg of hydrogen delivered. Liquid oxygen can be delivered over 1600 km of sea at a cost of less than half that of oxygen gas delivered by under- water pipeline. This estimated cost of liquefying and shipping oxygen, for combustion with hydrogen, would increase the cost of hydrogen fuel by about 20 percent and may well be an acceptable penalty in some hydrogen fuel applications. Definitive studies are needed in this area. The efficiency of liquid hydrogen fueled systems can be improved with technical advances in construction materials, insulation mater- ials, and handling procedures. Advanced construction materials should be lightweight, strong, inexpensive, resistant to hydrogen embrittlement and brittle fracture, and have low heat capacity and thermal conductivity. Considerable effort is needed to develop candidate composite construction materials. Advanced insulation materials should also be lightweight, inexpensive, have low heat capacity and thermal conductivity, and possess demonstrated constancy of thermal and physical properties. Insulation transfer standards must also be developed so that the thermal performance of insulations PAGENO="1155" 1149 can be compared to known standards at any qualified laboratory. Insulation systems, tailored to the application, should benefit from any improvements in insulation and construction materials; however, this field already offers considerable potential for innovative design work. Liquid hydrogen handling procedures, though highly developed and successful in the aerospace program, will have to be revised for commercial applications. The areas demanding the most attention are pressurization, stratification, liquid transfer, venting, purging or inerting operations, and gas recovery techniques. The consumer must also be guaranteed equity in the marketplace. Thus, traceable measurement standards are required for commercial liquid hydrogen fuel; mass flow, pressure, temperature, and quantity- gauging standards are required. Cryogenic instrumentation has not been significantly advanced in the past ten years. Major R&D efforts will be required to meet the needs of a commercial cryogenic hydrogen fuel market. Instruments suitable for aerospace applications are not appropriate for commerce and vice versa. Rugged and reliable instru- ments that can be inexpensively mass-produced are needed for commerce. Liquid hydrogen enjoys an enviable safety record in the aero- space industry; however, as hydrogen pervades the commercial fuel market, safety considerations will have to be re-evaluated. Large numbers of unskilled or moderately-skilled people will be handling hydrogen fuel, exerting a need for intrinsically safe or `foolproof' fuel systems. The safe use of hydrogen in commerce will require thorough re-evaluation of: 1) compatible materials of construction, 2) handling procedures and regulations, and 3) explosion hazards. The first two items require integration of existing knowledge (data and practices) with mature judgment. The third item requires that more definitive analytical and experimental work [29] be performed to permit more intelligent evaluation of potential explosion hazards. Specifically, experiments [29] should be performed to: a) determine the ignition energy of potential ignition sources, b) evaluate the effects of partial confinement on explosion overpressure and transi- tion-to-detonation, and c) evaluate the effectiveness of frangible walls in reducing explosion overpressures. Acceptable guidelines must be drafted (some already exist [29]) for the evaluation of thermal radiation, fireball, shrapnel, impulse and overpressure hazards in hydrogen fuel systems. It should be emphasized that this knowledge is needed to permit more realistic appraisals of potential explosion hazards and is not sought out of fear of increased explosive threat. Maximum explosive potentials of hydrogen fuel are already known. PAGENO="1156" 1150 2.4 Other Research Related to Cryogenic Hydrogen At least one other major market, related to cryogenic hydrogen, could develop in the next few years. This potential application is the cryopurification of hydrogen gas for recycle to the hydrogenation stage of a coal liquefaction plant. It is reasonable to expect that the common acid gases (C02, H~,S, etc.) will be removed from coal gas streams by conventional scrubbing techniques. This recycle gas stream, consisting largely of hydrogen and with minor concentrations of NH3 and CH4, will then be fed to a cryopurifier unit. The exact .cryogenic process to be used is highly dependent upon the desired purity of the hydrogen flowing out of the cryopurifier. The NH3 and CH4 components may be removed by expanding the high pressure recycle gas. stream through an expansion device (Joule-Thomson valve, etc.), by cooling with an auxiliary refrigerator, or a combination of both. Cryogenic absorption processes may also be used to purify this hydrogen recycle gas. NH~ and CH4 concentrations can be reduced to almost any desired level using these techniques. Design of these cryopurifiers would benefit from liquid-vapor and solid-vapor phase equilibria data for binary and ternary systems of NH3, CH4 and H2 mixtures. Another interesting, though speculative, research topic [301 has shown signs of revival in the past few years. Pure spin-aligned monatomic hydrogen, cooled to 4 K and contained in a magnetic field, has potential as a high-impulse rocket fuel. Metallic hydrogen, created by compressing cryogenic hydrogen to megabar pressures, - offers dual potential as a rocket propellant and as a high-temperature (-lOOK) superconducting metal. 3.0 SUNHARY Hydrogen is slowly but surely gaining favor as a commercial fuel and liquid hydrogen will capture some portion of this future market. Large-scale commercial use of liquid hydrogen will generate a need for new and improved hydrogen fuel systems. Adaptation of existing technology and development of improved technologies together with new and improved products offer numerous research and development (R&D) opportunities in the cryogenics field. Potential applications for cryogenic hydrogen are reviewed and some specific R&D targets are identified herein. CANDIDATE MARKETS for cryogenic hydrogen, without regard to priority or imminency, are: transportation -- to fuel aircraft, autos and ships; PAGENO="1157" 1151 aerosp~ē~ -- rocket and spacecraft fuel; energy storage and transnission -- carrier of nuclear or solar energy from sea-to-shore or overland; utilities -- fuel for integrated gas-electric utility operations and a portable fuel for rural communities; superconducting and cryoresistive electric~4~ppwer cables -- to be used as a closed-loop coolant (electricity only is delivered) or as an open-loop coolant (electricity and hydrogen are delivered); industrial processes -- to provide high purity hydrogen gas upon demand. R&D OPPORTUNITIES, again without regard to priority or imminency, are: liquefaction -- improve the efficiency of large liquefaction plants by using wet expansion engines and/or expansion ejectors in advanced liquefaction cycles and by improving the efficiency of gas compressors; recover liquefaction en~gy~ -- in those instances where the liquid must be vaporized for use, large stationary vaporizer installations will permit recovery of a portion of the energy required for liquefaction of hydrogen [potential techniques include recovery of isothermal- expander shaft work, obtaining more efficient combustion of hydrogen by consuming oxygen that is separated from air using the refrigeration capacity of liquid hydrogen, and scavenging by-product helium and rare gases (neon, krypton, xenon) from air in these air separation plants]; cryopurification -- use of cryogenic techniques to purify hydrogen recycle streams in coal liquefaction plants; ~y4~ogen-mixtures properties -- liquid-vapor and solid- vapor phase equilibria data for mixtures of NH3-CH4-H2 will aid in the design of cryopurifier units for coal liquefaction plants; instrumentation -- large scale commercial use of liquid hydrogen will demand a new generation of rugged, reliable, inexpensive instruments for measurement of quantity, mass flow, pressure, temperature, etc.; PAGENO="1158" 1152 measurement standards -- are needed to bring all aspects of cryogenic instrumentation under the control of the National Measurement System; transoceanic shipments -- the feasibility of using barges or ocean tankers to transport liquid hydrogen from sea- based power plants to population centers is in need of definitive study (if studies reveal that liquid hydrogen is a competitive means of transmitting energy from sea- to-shore or is a suitable media for energy import-export, R&D opportunities will exist for the design and construc- tion of appropriate ocean-going vehicles); construction materials -- lightweight, strong, compatible, inexpensive materials are needed for portable and station- ary fuel applications; insulation materials -- lightweight, efficient and inex- pensive materials are needed, as are improved insulation systems and the development of national insulation transfer-standards; handling procedures -- existing procedures will need revisions to accommodate new commercial applications of liquid hydrogen (notable areas in need of R&D efforts are pressurization, stratification, liquid transfer, venting, purging and gas recovery methods); safej~y -- intrinsically safe fuel system designs are needed and our existing knowledge of the explosive characteristics of hydrogen should be expanded to permit more realistic appraisal of potential explosion hazards (current precautions may be too restrictive). R&D is needed to assess the ignition energy of candidate ignition sources, and to appraise the effects of partial enclosures and frangible walls on explosion overpressures. 4.0 REFERENCES 1. Selected Topics on Hydrogen Fuel, Ed. by J. Hord, Nat. Bur. Stand. (U.S.), NBSIR 75-803 (Jan 1975). 2. Ibid., Sindt, C.F., Solar energy--liquid hydrogen, Chap. 7. PAGENO="1159" 1153 3. Fernandes, R.A., Hydrogen cycle peak-shaving for electric utilities, Proc. of 9th IECECI: 413-422 (Aug 1974). 4. Op. cit., Reference [1], Parrish, W.R., Hydrogen in the electri- cal utility industry, Chap. 2. 5. Salzano, F.J., (Brookhaven National Laboratory, Upton, N.Y.), private communication to the author; see also, Isler, R. J., Salzano, F.J., Suuberg, *E.M., and Yu, W.S., Reference design of a 26 MW(e) electric energy storage system, Informal Report No. BNL-l9231, Brookhaven National Laboratory, Upton, New York 11973 (July 1974). 6. Whitelaw, R.L., Electric power and fuel transmission by liquid hydrogen superconductive pipeline, Proc. of the Hydrogen Economy Miami Energy (THEME) Conference, Ed. by T.N. Veziroglu, S2-27, 36; (Available from the School of Continuing Studies, Univer- sity of Miami, P.O. Box 248005, Coral Gables, Fla. 33124). 7. Stewart, W.F., and Edeskuty, F.J., Alternate fuels for transpor- tation, Part 2; Hydrogen for the automobile, Mech. Engr. 96, No. 6, 22-28 (June 1974); see also, Stewart, W.F., Edeskuty, F.J., Williamson, K.D. Jr., and Lutgen, H.M.,. Operating experience with a liquid hydrogen fueled vehicle, Report No. LA-UR 74- 1637, Los Alamos Scientific Laboratory, Los Alamos, New Mexico 87544 (1974). 8. Billings, R.E., Hydrogen's potential as an automotive fuel, Cryogenics and Industrial Gases 9, No. 1, 23-25 (Jan/Feb 1974); see also, Billings, R.E., Hydrogen storage in automobiles using cryogenics and metal hydrides, Proc. of the Hydrogen Economy Miami Energy (THEME) Conference, Ed. by T.N. Veziroglu, S8-5l, 62; (Available from the School of Continuing Studies, University of Miami, P.O. Box 248005, Coral Gables, Fla. 33124). 9. Op. cit., Reference [1], Voth, R.O., H2 fueled automobiles, Chap. 3; see also, Hoffman, G.A., Hydrogen-rich automotive fuels: Future cost and supply projections, Proc. of 9th IECEC: 934-940 (Aug 1974); Hagey, F., and Parker, A.J. Jr., Technical and economical criteria for the selection of alternative fuels for personal automotive transportation, Proc. of 9th IECEC: 941-951 (Aug 1974). 10. Small, W.J., Fetterman, D.E., and Bonner, T.F. Jr., Alternate fuels for transportation, Part 1: Hydrogen for aircraft, Mech. Engr. 96, No. 5, 18-24 (May 1974). tlntersociety Energy Conversion Engineering Conference (proceedings printed by the ASME, United Engineering Center, 345 East 47th Street, New York, N.Y. 10017). PAGENO="1160" 1154 11. Brewer, G.D., The case for hydrogen-fueled transport aircraft, Astro. and Aero. 12, No. 5, 40-51 (May 1974). 12. Dickson, E.N., Logothetti, T.J., Ryan, J.W., and Weisbecker, L.W., The use of hydrogen in commercial aircraft--an assessment, Proc. of 9th IECEC: *468-478 (Aug 1974). 13. Johnson, J.E., The economics of liquid hydrogen supply for air transportation, Book, Advances in Cryogenic Engineering 19, Ed. by K.D. Timmerhaus, pp. 12-22 (Plenum Press, Inc., New York, N.Y. 1974). 14. Quandt, E., Investigation of hydrogen fuel for naval vehicles, Proc. of the Hydrogen Economy Miami Energy (THEME) Conference, Ed. by T.N. Veziroglu, S16-l, 2; (Available from the School of Continuing Studies, University of Miami, P.O. Box 248005, Coral Gables, Florida 33124). 15. Burger, J.M., Lewis, P.A., Isler, R.J., Salzano, F.J., and King, J.M. Jr., Energy storage for utilities via hydrogen systems, Proc. of 9th IECEC: 428-434 (Aug 1974). 16. Libowitz, G.G., Metal hydrides for thermal energy storage, Proc. of 9th IECEC: 322-325 (Aug 1974). 17. El-Badry, Y.Z., and Zemkoski, J., The potential for rechargeable storage batteries in electric power systems, Proc. of 9th IECEC: 896-902 (Aug 1974). 18. Brown, J.T., and Cronin, J.H., Battery systems for peaking power generation, Proc. of 9th IECEC: 903-910 (Aug 1974). 19. Walsh, W.J., Allen, J.W., Arntzen, J.D., Bartholme, L.G., Shimotake, H., Tsai, B.C., and Yao, N.P., Development of proto- type lithium-sulfur cells for application to load-leveling devices in electric utilities, Proc. of 9th IECEC: 911-915 (Aug 1974). 20. Mitoff, S.P., and Bush, J.B. Jr., Characteristics of a sodium- sulfur cell for bulk energy storage, Proc. of 9th IECEC: 916- 923 (Aug 1974). 21. Hassenzahl, W.V., Baker, B.L., and Keller, W.E., The economics of superconducting magnetic energy storage systems for load- leveling--A comparison with other systems, Report No. LA-5377- MS, Los Alamos Scientific Laboratory, Los Alamos, New Mexico 87544 (Aug 1973). PAGENO="1161" 1155 22. Boom, R.W., McIntosh, G.E., Peterson, H.A., and Young, W.C., Superconducting energy storage, Book, Advances in Cryogenic Engineering 19, Ed. by K.D. Timmerhaus, pp. 117-126 (Plenum Press, Inc., New York, N.Y. 1974). 23. Post, R.F., and Post, S.F., Flywheels, Scient. Amer. 229, No. 6, 17-23 (Dec 1973). 24. Air for peak generation goes into cold storage, Electrical Review 194, No. 14, 415 (Apr 1974); see also, Korsmeyer, R.B., Underground air storage and electrical energy production, Report No. ORNL-NSF-EP-ll, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830 (Feb 1972); Giramonti, A.J., and Lessard, R.D., Exploratory evaluation of compressed air storage peak- power systems, Energy Sources 1, No. 3, 283-294 (Crane, Russak & Company, Inc., 1974). 25. Zener, C., Solar sea power, Physics Today 26, 48-53 (Jan 1973). 26. Escher, W.J.D., Future availability of liquid hydrogen, Astro. and Aero. 12, No. 5, 55-59 (May 1974). 27. Op. cit., Reference [1], Parrish, W.R., and Voth, R.0., Cost and availability of hydrogen, Chap. 1. 28. Op. cit., Reference [1], Sindt, C.F., Transmission of hydrogen, Chap. 6. 29. Hord, J., Explosion criteria for liquid hydrogen test facilities, Nat. Bur. Stand. (U.S.), NBS Report (Feb1972). 30. Yaf fee, M.L., Atomic hydrogen rocket fuels studied, Aviation Week & Space Tech. 101, No. 21, 47-49 (Nov. 25, 1974). PAGENO="1162" 1156 NBSIR 75803 SELECTED TOPICS ON HYDROGEN FUEL W. R. Parrish R. 0. Voth J. G. Hust T. M. Flynn C. F. Sindt N. A. OUen J. Hord, Editor Cryogenics Division Institute for Basic Standards National Bureau of Standards Boulder, Colorado 80302 January 1975 0~ U.S. DEPARTMENT OF COMMERCE Frederick B. Dent, Secretary NATtONAL. BUREAU OF STANDARDS. Richard W Roberts. Director PAGENO="1163" 1157 ABSTRACT The National Bureau of Standards played a vital role in developing hydrogen technology for the space age and is now engaged in efforts to adapt and improve this technology for the commercial use of hydrogen fuel. This document is a summary report on selected hydrogen-fuel topics and was prepared to identify cost and technical barriers to the commercial use of hydrogen fuel and to generate reference data for policy-planning, decision- making and design. Cryogenic hydrogen fuel technology is emphasized in the economic and systems analyses reported herein. Using the best available technical and economic data, hydrogen fuel is not currently cost competitive with alternate fuels; however, we must not reject hydrogen on the basis of current economic comparisons. Increased efficiencies of production, liquefaction, and energy conversion may drastically change these comparisons- of-today as will increased fossil fuel prices and more stringent environmental and pollution constraints. Hydrogen appears currently marketable in certain integrated utility systems, in transoceanic transport of energy produced far at sea, and is a necessary element in a wide variety of growing industrial processes and in the liquefaction of coal. This publication identifies research and development needs within selected areas of NBS competence and future research plans are outlined. Key words: Conservation; conversion; cost; cryogenics, economics; embrittle- ment; energy; hydrogen; industrial, instrumentation, liquefaction; literature; materials; production; solar; storage; transmission; transportation; utilities. PAGENO="1164" 1158 PREFACE BACKGROUND. The National Bureau of Standards (NBS) has been actively engaged in hydrogen research for over twenty years and in mid-1972 our interests were rekindled by the obvious need for an abundant, clean-burning fuel. Convenient energy storage and distribu- tion, portable power and reduced air pollution are some of the advan- tages of recyclable hydrogen fuel. In the fall of 1972 the NAS~NAE_NRC* evaluation panel for the Cryogenics Division (CD) of the NBS recommended renewal of a modest effort on hydrogen fuel technology. The scientific staff of the NBS-CD responded enthusiastically and a state-of-the-art survey paper [1] was released in the summer of 1973. An economic analysis [2] of hydrogen-fueled electrical utility systems was published in March 1974, and a benchmark literature bibliography [3] was completed in June 1974. The work reported herein was initiated in July 1973. The rapid momentum achieved in this program was made possible by the cognizant support of management at all levels of the NBS, e~ g. Institute Director's Reserve funds were made available to initiate this study. National Academy of Science (NAS), National Academy of Engineering (NAE) and National Research Council (NRC). 1. Hord, 3., Cryogenic H2 and National Energy Needs, Book, Advances in Cryogenic Engineering 19, (Ed.) K. D. Timmerhaus, p. 1-11 (Plenum Press, Inc., New York, N. Y., 1974). 2. Parrish, W. R. , An Economic Study of Electrical Peaking Alternatives, Proceedings of THEME Conference, University of Miami, Coral Gables, Fla. (March 1974). 3. HYDROGEN FUEL - SUMMARY BIBLIOGRAPHY, Cryogenic Data Center, NES, Boulder, Cob. (June 1974). PAGENO="1165" 1159 Because the Cryogenics Division of the NBS is primarily concerned with low temperature research, this study emphasizes the cryogenic aspects of hydrogen fuel. In the market place the application dictates the most suitable physical form of the fuel and cryogenic hydrogen is a contender in many potential fuel systems. MOTIVATION. Hydrogen is a prime candidate to satisfy many long-term national (and international) fuel requirements. It is no longer necessary to justify hydrogen fuel research because hydrogen is a clear contender for the synthetic fuel market of the future- -only the time scale for implementation of this fuel is uncertain. Economical production of hydrogen,from coal or water, could easily occur within the next decade and initiate major transitions in current modes of distributing marketable energy. Thus, it is apparent that hydrogen fuel research will have a major impact on future dispensation of energy in this country and offers great potential benefit to the public. The need to accelerate hydrogen fuel research is accentuated by the fuel shortages that we have experienced over the past few years and by a nationally acclaimed goal- -energy-fuel self-sufficiency by 1985. The NBS has a history of assisting industry in major national programs. The NBS mission stresses conservation of our natural resources, equity in the marketplace, transfer of existing technology to industry and research applied to industrial needs. OBJECTIVE. Our goal is to provide the cryogenics industry with innovative cryogenic technology so that hydrogen may be liquefied, stored and distributed efficiently and with safety and fairness to the consumer. PAGENO="1166" 1160 APPROACH. Economic and systems analyses are performed to identify cost and technical barriers to the use of hydrogen fuel and to aid in program planning and definition. We endeavor to provide rational analyses based on the best available technical/economic information and to generate valid data for decision-making and design. The work reported herein was selected to 1) coincide with the NBS-CD mission, 2) avoid repetitious efforts and augment studies of others, 3) serve national interests by supplying unbiased technical assessments of hydrogen's potential as a fuel and, 4) provide authoritative reference data in areas where the NBS is uniquely qualified. This report was prepared for an interdisciplinary audience and is intended to afford maximum usefulness to the reader. Therefore, conventional units and terminology, common to the particular topic, are used in each chapter without regard for consistency from chapter- to-chapter. Metric units are used where appropriate. Each chapter is self-standing for ready reference; therefore, there is necessarily some overlap in individual chapter narratives. Authors of these chapters are senior staff scientists and engineers of the Cryogenics Division of the NBS. PROGRESS. Analyses and summary reports are presented herein--the topics covered are: (1) cost and availability of hydrogen, (2) hydrogen in the electrical utility industry, (3) hydrogen-fueled automobiles, (4) survey of materials for hydrogen service, (5) instrumentation for cryogenic hydrogen fuel, (6) transmission and distribution of hydrogen, (7) solar energy- -liquid hydrogen, (8) industrial applications of hydrogen and (9) hydrogen fuel literature. PAGENO="1167" 1161 SUMMARY. Based on current economic data, hydrogen fuel appears economically marginal in auto transportation and in electrical utility systems; however, we must be continuously aware that these conclu- sions are influenced by cost parameters that are changing daily. Consequently, cost parameters are provided in this study so that cost comparisons can be readily upgraded to reflect future cost factors, by-product credits and technological advances. Also, cost factors are not currently known well enough to justify elimination of hydrogen fuel on economic grounds. At this writing hydrogen appears attractive as an aircraft and aerospace fuel, in certain integrated gas-electric utility systems (e. g. , use of hydrogen to store solar or off-peak electrical energy), for transport of energy from solar sea power plants and is an essential ingredient in a wide variety of prolific industrial processes. Widespread use of hydrogen fuel will generate a significant need for construction and insulation materials research--this need for materials with suitable characteristics is defined herein. Cryogenic instrumentation has not noticeably advanced in the past ten years. Large scale commercial use of cryogenic hydrogen will require major research and development efforts in this area. When liquid fuel is required, our cost study shows that it is usually economically prudent to produce liquid hydrogen at the use-site. It is advantageous to liquefy hydrogen at the source when energy must be transported from power plants far at sea. The NBS-CD provides hydrogen fuel literature services for the general public and these services are described herein. PAGENO="1168" 1162 PLANS. Priority research elements that have been identified and selected for future study are: (1) improve hydrogen liquefaction efficiency, (2) evaluate methods of recovering liquefaction energy and, (3) evaluate hydrogen compatible materials of construction. Long-term plans include the development of insulation transfer standards, the development of improved insulation systems and the standardization of measurement techniques for commercial exchange of liquid hydrogen. J. Hord December, 1974. PAGENO="1169" 1163 CONTENTS Page Preface CHAPTER 1. COST AND AVAILABILITY OF HYDROGEN 1. 1 W. R. Parrish and R. 0. Voth 1.0 Summary 1.1 1. 1 Introduction 1. 2 1. 2 Gaseous Hydrogen Sources and Production Techniques 1. 2 1. 2. 1 Hydrogen from Fossil Fuels 1. 2 1.2.2 Economics 1.4 1. 2. 3 Hydrogen from Water 1. 4 1. 2. 4 Thermochemical Decomposition of Water 1.7 1. 2. 5 Other Methods of Producing Hydrogen from Water 1.8 1. 3 Cost to Make Liquid, Slush, and Solid Hydrogen from Gaseous Hydrogen 1. 9 1. 4 Hydrogen Cost Credits i. 16 1. 4. 1 Oxygen By-Product Credit 1. 16 1. 4. 2 Deuterium By-Product 1. 16 1. 4. 3 Recovery of Liquefaction Energy 1. 19 1. 5 References 1. 25 CHAPTER 2. HYDROGEN IN THE ELECTRICAL UTILITY INDUSTRY 2. 1 W. R. Parrish 2. 0 Summary 2. 1 2. 1 Introduction 2. 2 2. 2 Economic Analysis 2. 6 2. 2. 1 Basic Assumptions z, 6 2. 3 Cost Data 2. 7 2. 3. 1 Power Generation Units 2. 7 2. 3. 2 Fuel Production and Storage 2. 8 2. 3. 3 Energy Storage Systems 2. 10 2. 4 Economic Comparison z. ii 2. 4. 1 Peaking Units z. ii 2. 4. 2 Intermediate Units 2. 19 2. 5 Conclusions 2. 19 2. 5. 1 Peaking Duty 2. 19 2. 5. 2 Intermediate Duty 2. 25 2. 5. 3 Base Load Duty 2. 25 2. 6 Hydrogen in Power Generation 2. 25 2. 7 Acknowledgment z. 25 2. 8 References 2. 26 2. 9 Appendix A: Sample Calculation of Power Production Cost 2. 28 2. 9. 1 Power Generating Unit 2. 28 2. 9. 2 Electrolysis Unit 2. 29 2. 10 Appendix B: Hydride Storage Cost Data 2. 29 62-332 0 - 76 - 74 PAGENO="1170" 1164 CHAPTER 3. H2 FUELED AUTOMOBILES 3. 1 R. 0. Voth 3. 0 Summary 3. 1 3. 1 Introduction 3. 1 3. 2 Safety of Hydrogen Fuel 3. 2 3. 3 Power Generating Devices for Use with Hydrogen 3. 3 3. 3. 1 The Internal Combustion Engine Using Hydrogen Fuel 3.4 3. 3. 2 External Combustion Engines 3. 6 3. 3. 3 Fuel Cells 3. 6 3. 4 Fuel Storage Aboard a Vehicle 3. 8 3. 5 Economic Analysis of the Use of Hydrogen Fuel for a Small Automobile 3. 10 3. 6 References 3~ 22 CHAPTER 4. SURVEY OF MATERIALS FOR HYDROGEN SERVICE 4. 1 J. G. Hust 4. 0 Summary 4. 1 4. 1 Introduction 4. 1 4. 2 Hydrogen Related Materials Properties 4. 3 4. 2. 1 Temperature Effects 4. 4 4. 2. 2 Hydrogen Embrittlement, Diffusion and Permeation 4. 9 4. 2. 3 Insulation 4. 14 4. 2. 4 Oxygen Compatibility 4. 16 4. 3 Materials Requirements for Hydrogen Production 4. 18 4. 3. 1 Electrolysis 4. 18 4. 3. 2 Thermochemical 4. 19 4. 3. 3 Other Production Methods 4. 19 4. 3. 4 Hydrogen Liquefaction and Solidification 4. 19 4. 4 Material Requirements for Hydrogen Transfer and Storage 4. 20 4. 4. 1 Gaseous Hydrogen 4. 20 4. 4. 2 Liquid and Frozen Hydrogen 4. 21 4. 4. 3 Hydride Storage 4. 23 4. 5 Materials Requirements for Hydrogen Applications 4. 23 4. 5. 1. Heating 4. 23 4. 5. 2 Propulsion 4. 24 4. 5. 3 Electric Power Generation 4. 24 4. 6 Recommendations 4. 25 4. 6. 1 Structural Materials Research 4. 25 4. 6. 2 Insulation Research 4. 26 4. 6. 3 Catalytic Matecial Research 4. 26 4. 7 Acknowledgments 4. 26 4. 8 References 4. 27 PAGENO="1171" 4. 9 Appendix: List of Recent and On-Going Hydrogen Related Material Research 4. 9. 1 Material Development Projects 4. 9. 2 Hydrogen-Environment Embrittlement Projects 4. 9. 3 Internal Embrittlement Projects 4. 9. 4 Hydride Embrittlement Projects 4. 9. 5 Embrittlement Inhibitor Projects 4. 9. 6 Hydrogen Diffusion Projects 4. 9. 7 Hydrogen and NDT Failure Detection Projects 4. 9. 8 Hydrogen Production and Trans- mission Projects 4. 9. 9 Hydrogen Storage Projects 4. 9. 10 Propulsion Systems Projects 4. 9. 11 Bearings, Seals and Lubricants Projects 4. 9. 12 Fuel Cells Projects CHAPTER 5. INSTRUMENTATION FOR CRYOGENIC HYDROGEN FUEL T. M. Flynn 5. 0 5. 1 5. 2 Summary Introduction Pressure 5. 2. 1 Pressure Transducers 5. 2. 2 Steady State Temperature Effects 5. 2. 3 Thermal Shock Effects 5. 2. 4 Methods of Avoiding Temperature Effects on Pressure Transducers 5. 2. 5 Pressure Summary 5. 3 Temperature 5. 3. 1 `Fluid Thermometry 5. 3. 2 Metallic Resistance Thermometry 5. 3. 3 Non-Metallic Resistance Thermometry 5. 3. 4 Thermocouples 5. 3. 5 Temperature Summary 5. 4 Liquid Level 5. 4. 1 Point Liquid Level Sensors 5. 4. 2 Continuous Liquid Level Sensors 5. 4. 3 Liquid Level Summary 5. 5 Density 5. 5. 1 5. 5. 2 5. 5. 3 5.5.4 5. 5. 5 5. 5. 6 5. 5. 7 1165 4. 38 4. 38 4.39 4.40 4.43 4.46 4.46 4.47 4.48 4.49 4.50 4.51 4.52 5. 1 5. 1 5. 2 5. 3 5. 3 5.4 5.4 5. 5 5. 5 5. 7 5. 7 5. 8 5. 10 5. 11 5. 12 5. 14 5. 15 5. 16 5. 18 5. 19 5. 19 5. 19 5. 19 5, 19 5.20 5, 20 5.21 Direct Weighing Method Buoyant Force Method Differential Pressure Method Capacitance Method Optical Method Acoustic Method Ultrasonic Method PAGENO="1172" 1166 5. 5. 8 Momentum Methods 5. 22 5. 5. 9 Nuclear Radiation Method 5. 23 5. 5. 10 Density Summary 5. 24 5. 6 Flow 5. 24 5. 6. 1 Head Meters 5~ 24 5. 6. 2 Turbine Type Meters 5. 25 5. 6. 3 Vortex Shedding Meter 5. 26 5. 6. 4 Momentum Mass Flowmeters 5. 27 5. 6. 5 Flowmeter Summary 5. 30 5. 7 References 5. 31 CHAPTER 6. TRANSMISSION OF HYDROGEN 6. 1 C. F. Sindt 6. 0 Summary 6. 1 6. 1 Introduction 6. 1 6. 2 System Descriptions 6. 2 6. 3 System Analysis 6. 2 6. 4 Results 6. 5 6. 5 Conclusions 6. 7 6. 6 References 6. 11 CHAPTER 7. SOLAR ENERGY- - LIQUID HYDROGEN 7. 1 C. F. Sindt 7.0 Summary 7.1 7. 1 Introduction 7. 1 7. 2 System Descriptions 7. 2 7. 3 Sizing System Components 7. 5 7. 4 Estimated Performance of System Components 7. 6 7. 5 Comparison of the Operation of Systems 7. 6 7. 6 Costs 7. 7 7. 7 References 7. 10 CHAPTER 8. INDUSTRIAL APPLICATIONS OF HYDROGEN 8. 1 \~T R. Parrish. 8. 0 Summary 8. 1 8. 1 Introduction 8. 1 8. 2 Petroleum Refining 8. 1 8. 3 Ammonia Production 8. 2 8. 4 Other Uses of Hydrogen 8. 2 8. 5 Future Uses of Hydrogen 8. 2 8. 6 References 8. 3 CHAPTER 9. HYDROGEN FUEL LITERATURE 9. 1 N. A. Olien 9. 0 Summary 9. 1 9. 1 Introduction 9. 1 9. 2 The Cryogenic Data Center 9. 1 9. 3 Services and Products of the Cryogenic Data Center 9. 2 9. 4 Hydrogen Safety Information 9. 4 9. 5 Hydrogen Properties Handbook 9. 4 9. 6 References 9. 7 PAGENO="1173" 1167 CHAPTER 1 COST AND AVAILABILITY OF HYDROGEN W. R. Parrish and R. 0. Voth 1.0 SUMMARY The feasibility of using hydrogen as a fuel will be determined by the availability and cost of hydrogen. This chapter considers techniques and costs of producing gaseous hydrogen along with costs of producing liquid, slush and solid hydrogen. It also examines the poten- tial by-products that could lower the overall cost of using hydrogen. Fossil fuels and water are the two sources of hydrogen. Today most industrial hydrogen is derived from hydrocarbons (mainly natural gas) and costs 10 to 15c/kg to produce. When natural gas costs more than approximately 801/MBTLJ, coal becomes a competitive source with production costs of 20 to 25c/kg. MBTU = BTU x l0~ throughout this chapter. As the fossil fuels are depleted, water will become the principal source of hydrogen. The two most promising means of producing hydrogen from water are electrolysis and thermo- chemical decomposition. Although electrolysis is an existing technology, it is not cost competitive with other existing processes unless electrical power costs less than 5 mills/ kW-h--exceptions occur in those cases where ultra-high purity and/or small quantities of hydrogen are required. Thermochemical decomposition uses a combination of heat and chemicals to decompose water; the process requires several intermediate steps involving chemical re- actions and separations. Thermochemical decomposition offers the possibility of producing hydrogen from water at lower cost and more efficiently than electrolysis; however, this hydrogen will still be more expensive than hydrogen produced from fossil fuels (even when fossil fuels cost double their current price). Using current technology, it costs 15 to 201/kg to liquefy, slush or solidify hydrogen in a high capacity plant. In terms of energy required, it takes 20 to 30 percent of the lower heating value of hydrogen to convert it into the condensed phases. Although the economic and energy penalties are significant, the end-use of the fuel prescribes the opti- mum physical state of hydrogen. At least three by-products of hydrogen production and liquefaction could increase the economic attractiveness of hydrogen as a fuel: oxygen, deuterium, and recovery of liquefac- tion energy. If hydrogen is produced from water, selling the by-product oxygen could reduce the selling price of hydrogen by as much as lOc/kg, provided the oxygen demand met the supply. Distillation of liquid hydrogen offers an attractive means of obtaining deuterium which is a fuel for fusion reactors. Current estimates indicate that sale of deuterium could lower the cost of liquid hydrogen by 2 to 3c/kg. Although the maximum amount of energy recoverable from liquefaction is only 10 percent of the heat of combustion, it represents a significant amount of energy in large vaporizing facilities. A preliminary analysis indicates that 25 percent of the ideal liquefaction energy of a kilogram of hydrogen is comparable to the actual separation energy required to extract eight kilograms of oxygen from air. This observation implies an overall energy recovery system efficiency of about ten percent. Thus, the refrigeration energy recovered by warming a liquid hydrogen stream could theoretically PAGENO="1174" 1168 power an air separation plant sized to provide enough oxygen for stoichiometric combustion with the hydrogen stream. This availability of both oxygen and hydrogen at the use-point may prove both economically and environmentally attractive. 1.1 INTRODUCTION This chapter discusses methods of producing and liquefying hydrogen. The first section covers methods of hydrogen production. Whenever possible, production costs are included. The second section covers the cost of producing liquid, slush and solid hydrogen. These costs include the cost of purifying the hydrogen. The effect of cycle efficiency on produc- tion costs is also demonstrated. The last section looks at possible by-products of hydrogen which could reduce the net cost of hydrogen. It also discusses the feasibility of recovering liquefaction energy. 1.2 GASEOUS HYDROGEN SOURCES AND PRODUCTION TECHNIQUES The two primary sources of hydrogen are fossil fuels and water. This section briefly describes some of the more important hydrogen producing processes. It also considers some innovations which could become important in the future. 1.2.1 Hydrogen from Fossil Fuels There are at least five processes for producing hydrogen from fossil fuels. Today most of the hydrogen in the U.S. cones either from steam reforming or partial oxidation of hydro- carbons.1 As hydrocarbon stocks become more expensive, coal gasification will become an important hydrogen-producing process. This subsection briefly describes these three pro- cesses. For more details about all of the processes, excluding coal gasification, one can refer to reference books such as Faith, Keyes, and Clark [11.2 Steam Reforming: Steam reforming of hydrocarbons is the major source of industrial hydrogen today; it produces relatively high purity (97%) hydrogen in a two or three stage process. The first stage is the reforming stage where steam and hydrocarbons react over a nickel catalyst in a furnace operating at 1000 to 1200 K and 30 atm. The basic reactions are: CH + m H2O f mCO + (m + n/2)H2 CH+2mH2O~fmCO+ (2m+n/2)H2. The product gas containing H2, CO, and CO2 goes to a shift converter where it is mixed with more steam and undergoes the following reaction: CO + H20 CO2 + H2. 1 Hydrogen is a major by-product in the catalytic reforming of petroleum. Since the hydrogen is consumed within the refinery, this process will not be discussed here. 2 Numbers in brackets indicate references at the end of this paper. PAGENO="1175" 1169 The shift converter requires an iron catalyst and operates at a lower temperature (900 K). Whereas the reforming is endothermic, the converter reaction is exothermic; this heat is used to generate some of the process steam. After cooling the converter gas to around 350 K, the gas is scrubbed with a caustic or an ethanolamine to remove the carbon dioxide. To obtain 97% H2, the gas goes through another shift conversion and scrubbing. Many times part of the feedstock is the fuel for the reforming furnace; waste heat in the flue gas generates roughly half of the steam required in reforming. Quade [2] suggests using a nuclear high temperature gas reactor (HTGR) to supply the process heat. Huclear heat has the attraction of reserving hydrocarbons for chemical purposes instead of using them as fuels. Partial Oxidation: The partial oxidation process produces hydrogen by partial burning of the hydrocarbon; the overall reaction is CmHn + l/2(m + n + x - y)02 -~ xCO2 + (m-x)C0 + yH2 + (n-y)H20, where x and y are respectively, the number of moles of carbon dioxide and hydrogen produced per mole of feedstock. The reaction apparently goes to completion because only a trace of oxygen is found in the synthesis-gas stream. The process is attractive because the reaction requires no catalyst and has a high thermal efficiency (60%)[3]. However, the process re- quires an oxygen plant which is roughly 25% of the total capital cost. The operating con- ditions are comparable to those in steam reforming but in this process the reactants are preheated before entering the reactor. As in the case of steam reforming, to obtain a high purity product, the syn-gas must go through one or two stages of shift conversion and scrubbing. Coal Gasification: Coal gasification is a relatively new technology and not yet fully developed in this country. Although most of the gasifier research today relates to low or high BTU gas and liquefaction processes, the same gasifier technology can be used to produce hydrogen from coal. In fact, most liquefaction processes require large amounts of hydrogen (-7000 SCF/bbl of synthetic liquid [4]) and coal may be the most economical source of hydrogen gas in the future. The coal gasification process is quite similar to the partial oxidation process except that instead of preheating the reactants, they are heated in the gasifiers by the partial oxidation of coal.3 Steam is required to supply an additional source of hydrogen according to the reaction C + H2O~CO + H2. To produce hydrogen from coal requires 1.7 kg of steam per kg of coal consumed (0.3 kg in the gasifier) and 0.75 kg of oxygen per kg coal. This all produces 0.16 kg of hydrogen at 97% purity [3]. (This particular process used only one shift converter.) In theory, this same process could be used to produce hydrogen from garbage or other organic wastes. PAGENO="1176" 1170 1.2.2 Economics Figure 1.1 gives the production cost of hydrogen from various fossil fuels and by electrolysis. This figure assumes that all of the different hydrogen production plants have a capacity of 180 million SCYD (17750 kg/h). The solid portions of the curves re- present current or near-term raw materials coat (or electricity in the case of electrolysis). Figure 1.2 shows our estimated selling price of hydrogen for the various processes. The selling price is based on a discount cash flow of 18%, it includes a 50% state and federal tax rate and straight-line depreciation over 20 years. It excludes transmission costs and local taxes. Based on these curves, the cheapest source of hydrogen is natural gas--providing it costs less than roughly 80t/MBTU. Higher costs make coal competitive. The current cost of fuel oil makes it a much less attractive source of hydrogen. 1.2.3 Hydrogen from Water The most abundant source of hydrogen is water. Electrolysis is the only commercial process existing today for obtaining hydrogen directly from water. However, several new techniques are under development, the most promising alternate approach is thermochemical decomposition. Electrolysis and thermochemical decomposition are considered first, while the more exotic methods are discussed at the end of this section. Water Electrolysis: Electrolysis produces a high purity hydrogen, which today is more expensive than hydrogen from hydrocarbons. Some reasons for this include: 1. It takes more energy to remove hydrogen from water than from hydrocarbons. 2. Electrolysis requires a high-grade energy (electricity), whereas hydrocarbon reduction requires a low-grade energy (heat). 3. Hydrocarbons are usually relatively cheap compared with electrical power. However, electrolysis becomes attractive if power is inexpensive or where hydrogen demand is too small to justify a hydrogen-from-fossil fuels plant. Also, as nuclear power becomes sore important, the third reason may vanish. The basic electrolysis unit consists of two electrodes, which are separated by a membrane and immersed in water. Since pure water conducts electricity poorly, a strong electrolyte, such as potassium hydroxide, is added to the water to reduce ohmic losses. As current passes through the electrodes, hydrogen evolves from the cathode and oxygen from the anode. The hydrogen production rate is directly proportional to the current; from Faraday's law, each kilogram of hydrogen produced requires 26,532 ampere-hours. In theory, only the free energy (237.3 kJ/g-mol at 25'C and 1 atm) of dissociation needs to be supplied by electricity. The remaining portion of the heat reaction (286.0 kJ/g-mol at 25'C and 1 atm) can be supplied by heat from the surroundings or from ohmic losses within the cell. However, commercial cells operate at such a low efficiency that heat must be removed from the cell. For a given cell design, the cell efficiency is inversely proportional to the current density. However, the lower the current density, the greater the number and/or size of cells (and capital cost) required to provide a given hydrogen production rate. Thus, the optimum current density depends upon the relative contributions of fixed costs (i.e., costs related to capital investment) and operating costs (i.e., power, labor and maintenance costs). Based on an advanced cell design [51, the optimum current PAGENO="1177" 1171 CURVE 1 Coal Gasification 2 Steam Reforming of Methane 3 Partial Oxidation of Methane 4 Partial Oxidation of Fuel Oil 5 Electrolysis (LHV) (HHV) POWER COST FOR 0 5 5.0 F- F- `I, C L) 23.0 F- L) = C 2.0 1.0 0 ELECTROLYSIS, mills/kW-h 10 15 * Raw material costs are commonly based on HHV. FIGURE 1.1 Hydrogen Production Cost vs. Raw Material Cost for Various Processes, 18Ox1O6SCFD Plant. HHV=High Heat Value and LHV=Low Heat Value. 2 0.50 ~ F- V) C (-) cD L) = C 0. w C C >- = 1.0 2.0 3.0 4.0 RAW MATERIAL COST $/MBTU(HHV) PAGENO="1178" 1172 CURVE 1 Coal Gasification 2 Steam Reforming of Methane 3 Partial Oxidation of Methane 4 Partial Oxidation of Fuel Oil 5 Electrolysis POWER COST FOR ELECTROLYSIS, mills/kW-h 5 10 15 0 1.0 2.0 3.0 4.0 * RAW MATERIAL COST, $/MBTU(HHV) * Raw material costs are commonly based on HHV. FIGURE 1.2 Selling Price of Hydrogen vs. Raw Material Cost for Various Processes, 18Ox1O6SCFD Plant. HHV=High Heat Value and LHV=Low Heat Value. (LHV) (HHV) 0 5. 4.0 - 5.0 - 4.0 3.0 2.0 w 0. -J -J w w D 3.0 0.60 0.50 ~ w 0.40 ~ 0~ 0.30 0.20 ~ >- 0.10 1.0 2.0 1.0 0 0 5.0 PAGENO="1179" 1173 density decreases roughly 25 - 30% if the cost of power doubles. However, as figures 1.1 and 1.2 point out, for any reasonable power cost, the cost of power is the major component of the total cost. Several ways are being pursued to lower the cost of hydrogen via electrolysis. One obvious way is to improve electrode efficiency at high current densities while keeping the capital costs down. Assuming constant capital costs and a power cost of 10 mills/kW-h, the selling price of hydrogen would vary from 4 $/MBTU to 3 $/MBTU if the cell efficiency increased from 77 to 100% (i.e., low-grade heat, taken at no charge would have to be added); this gives a rough lower bounds on hydrogen costs that could never be obtained in coer- cial units. If high pressure hydrogen is the end product, electrolysis has an advantage in that the free energy change is a weak function of pressure at temperatures below 400 K [6]. Therefore, the unit has very little penalty in power consumption at high pressures. How- ever, more heat must be added because the heat of reaction is increased. Also, the econo- mics of using high pressure vessels must be included. Even so, Kincaide [7] believes that high pressure electrolysis could be attractive at pressures of 6 WHIm2 with conventionally designed electrodes. Conventional electrode designs use membranes made of materials such as asbestos to separate the electrodes. The membrane prevents mixing of the evolved gases but permits the flow of ions, electrons, and water between compartments. These membranes can be a source of problems if the cell is operated at elevated pressures. One solution to this problem is to use a solid polymer electrolyte (SPE) [6]. This system replaces the membrane with a polymer that, when saturated with water, becomes a good conductor. The SPE is strong enough to withstand high differential and operating pressures. It has the additional ad- vantage of eliminating the strong electrolyte, which can cause corrosion problems in the gas collecting system. Nutall et al. [6] claim that future developments will make the SPE concept competitive with conventional electrolysis systems, both in higher efficiency and lower capital and operating costs. 1.2.4 Thermochemical Decomposition of Water There has been a recent surge of interest in producing hydrogen from water via thermochemical processes. The primary attraction is that heat, probably nuclear or solar, instead of electricity is used, which could reduce production costs and increase the over- all efficiency. (The overall efficiency of electrolysis is limited by the conversion of heat to electricity.) The processes fall into two categories--open and closed cycle. Open-cycle systems consume the reactants; examples of open-cycle processes include coal gasification and shift conversion, which were discussed previously in this section. Today the main interest is in closed-cycle systems. A hypothetical two-step, closed- cycle process is X + H2O XO + H2 XO + heat -~ X + 1/2 02 PAGENO="1180" 1174 so that the net reaction is H20--H2+l/202. However, the processes being considered contain three to six steps and reaction tempera- tures ranging from 273 to 1200 K. From a capital and operating cost standpoint six steps is the maximum if the process is to compete with electrolysis. On the other hand, Funk and Reinatrom [8] found that no material X exists which could make the two-step cycle above as efficient as electrolysis. The same is probably true for three step processes; therefore, the optimum processes will probably contain four to six steps. Many organizations are investigating possible closed cycles 19]. Possible cycles must first be evaluated using thermodynamics. As Funk et al. [10] points out, the work of separation and degree of completion of each reaction must be considered. Incomplete reac- tions result in larger recycle streams and increased separation work; both of these problems decrease the economic feasibility of the cycle. If the process looks thermodynamically attractive and offers minimal corrosion problems (many of the most promising reactants are corrosive), then the reaction kinetics must be studied. Usually this takes a substantial effort, especially if gas phase reactions and/or catalysts are involved. Several processes have passed the thermodynamics stage and are in the kinetics stage. At this time, any economic analysis of closed-cycle thermochemical processes must be considered preliminary; however, Wentorf and Hanneman [11] estimate production costs to be at least 2.60 $/MBTU. Comparing these costs with data shown on figure 1.1 indicates that this process could be competitive with electrolysis; but even if the anticipated p~ice range of coal were doubled, hydrogen from coal would still be cheaper. 1.2.5 Other Methods of Producing Hydrogen from Water This section includes some of the more speculative methods suggested for producing hydrogen. The technical feasibility of sone of the methods is questionable, and an economic analysis of the process at this time would be meaningless. High Temperature Decomposition: The free energy of decomposition of water vapor de- creases and the concentrations of free oxygen and hydrogen increase with increasing tem- peratures. Thus, water can be decomposed at high temperature using only heat. This concept seems promising, but no one has found a way of separating hydrogen from the gas mixture at 3000 K. The separation cannot be made at lower temperatures because the hydrogen and oxygen will recombine. (The equilibrium mole fraction of hydrogen at 3000 and 1000 K are 0.65 and 106 respectively [12].) Just the material problems make thermal cracking look unattractive, even if the heat source were available. High Temperature Electrolysis: Operating an electrolysis unit at higher temperatures lowers the electrical energy input because the free energy is lower; e.g., operating at 1000 K instead of 300 K reduces the electrical energy demand by roughly 10%. However, solid electrolytes, similar to the solid polymer electrolyte, that can operate at high temperatures need to be found (SPE cannot operate long at temperatures above 380 K); also, gasket materials are a problem at higher temperatures [6]. PAGENO="1181" 1175 Ultra-Violet Photolysis of Water: Eastlund and Gough [13] suggest using ultraviolet photons to photodissociate water. The photon source would be leakage plasma from a fusion reactor. It is possible that this process will have a higher overall efficiency than the conventional electrolysis system. However, the process must wait for the development of fusion reactors, which may not occur before the year 2000 or later. Biophotolysis of Water: Mitsui [14] is investigating the use of microorganisms and sunlight to produce hydrogen. This concept is attractive because it offers the potential of a relatively high conversion efficiency of sunlight to chemical energy, at least when compared to conventional solar heat-to-hydrogen systems. However, many problems must be solved before the process can be considered commercially viable. 1.3 COST TO MAKE LIQUID, SLUSH, AND SOLID HYDROGEN FROM GASEOUS HYDROGEN Producing liquid, slush, and solid hydrogen from gaseous hydrogen requires capital investment, energy expense, and operating expense for the liquefier and/or refrigerator. An estimate of these costs can be obtained using information from a survey and correlation of current refrigerator/liquefier capital costs and energy requirements by Strobridge [15]. Liquefaction costs presented herein include the cost of gas purification; however, we are unable to supply a breakdown of purifying costs, as these are proprietary industrial data. Figures 1.3 and 1.4 are reproduced from Strobridge's report to show the efficiencies and capital costs of existing refrigerators and liquefiers. The numerous points on the curves show the performance for refrigerators and liquefiers at various low temperatures using various cryogenic fluids. The basis of comparison is the ratio of ideal work to actual work of producing refrigeration or liquid. Figure 1.3 shows the efficiency of refrigerators versus the refrigerator capacity. To convert the refrigeration capacity to an equivalent liquefier capacity, the refrigera- tion capacity from the graph is multiplied by the ideal work of compression per unit of refrigeration at the liquefaction temperature of interest and divided by the ideal work of liquefaction per unit of liquid. The ideal work of compression per unit of refrigeration is defined as the work re- quired by an ideal Carnot cycle refrigerator operating between the same temperature limits. For a unit operating at hydrogen temperatures this work is W = T~T~ - 300-20 = 14 watts/watt. The ideal work per unit of product for a liquefier can be derived from the thermodynamic availability of the product. Thermodynamic availability is defined by A = T (s - ~ - h + hL where T is the absolute temperature, a is specific entropy, and h is specific enthalpy. The subscript o designates ambient conditions and L designates the low temperature product condi- tions. Table 1.1 is a list of ideal work requirements for various cryogenic states of hydrogen. PAGENO="1182" I02 o 10 z a: 4 U z Ui U a: I. `0-s 102 CAPACITY, WATTS Figure 1.3 Efficiency of low temperature refrigerators and liquefiers as a function of refrigeration capacity. PAGENO="1183" a I- U) 0 0 IN PUT POWER, kW Figure 1.4 Cost of low tempersture refrigerstors snd liqu~fiers as a function of installed input power. PAGENO="1184" 1178 It is assumed that normal hydrogen at 1 atmosphere pressure and 300 K is used to produce cryogenic parahydrogen in the various states. Figure 1.4 shows the capital investment required for conmiercial refrigerators and liquefiers [15]. The cost is plotted against the installed compressor power of the available units. The line on the plot is for the equation C 6000 P°~7 where P is the kilowatts of installed compressor power, C is coat in dollars (1973). This equation is used to calculate capital investment costs in this section. In order to determine the cost of producing liquid, slush, or solid hydrogen, the cost of the required power, the operating and maintenance costs (0&N), and the fixed charges on the capital investment must be included. The fixed charges are based on operation of the plant 90 percent of the time. The power costs are simple functions of the ideal power re- quirements and conversion efficiency. The 0&M costs include maintenance, labor and operating costs other than fuel costs. The fixed charges include interest on the capital investment and debt retirement. The cost of land for the liquefier installation is neglected in the cost- ing figures. Table 1.1 Ideal work required to liquefy, slush or solidify hydrogen. (Initial state of normal hydrogen gas: pressure, 1 atm absolute; temperature, 300 K.) Final State Ideal Work Required kW-h/kg kW-h/lb Btu/lb Saturated liquid at 1 atm 3.971 1.801 6147 Slush hydrogen:50-50 mixture of solid-liquid by weight at triple point temperature and pressure 4.375 1.985 6773 Solid hydrogen at triple point temperature 4.543 2.061 7032 Table 1.2 shows the capital costs and energy requirements for various sized units. The 3500 kg/h capacity approaches the capacity of the largest plant currently in service with the larger capacities being an extrapolation of the trends apparent in the existing units. The efficiency figures were based on existing plant operations with a reasonable extrapolation to a 40 percent efficient process for the largest plant. The production of slush hydrogen (a 50-50 mixture of solid and liquid by mass) is a batch process [161. Because of the batch process inefficiencies and the lack of definitive data, the efficiency of the overall slush manufacturing process was arbitrarily reduced by one percentage point and costs were based on this assumption. For the large plants considered herein, this assumption is considered reasonable. PAGENO="1185" 1179 Table 1. 2 Capital costs and energy requirements for producing cryogenic hydrogen from gaseous hydrogen. Liquid Hydrogen Plant Size EFF Cost 1 Energy Requirements kg/h % 1973 dollars kW-h/kg 100, 000 40 94. 61 x 106 9. 93 7,000 35 16. l5x io6 11.35 3,500 34 10. 14x io6 11.68 1,500 33 5.72x ~ 12.03 500 30 2.84 x 106 13.24 100,000 Slush, Solid-Liquid (50-50 mixture by mass) Hydrogen 39 103. 06x 106 11.22 7,000 34 17.63x 106 12.87 3,500 33 ll.08x io6 13.26 1,500 32 6.26x 106 13.67 500 29 3. 11 x 106 15. 09 100, 000 Aux Ref~ Triple-Point Solid Hydrogen 9. 93 2. 23 40 94. 61 x l0~ 40 33. 29 x 10 7,00Q Aux Ref 35 16. 15 x l0~ 30 6. 33 x 10 11.35 2. 98 3,500 Aux Ref 34 9.38x l0~ 29 3. 99 x 10 11.68 3. 08 1,500 Aux. Ref 33 5.72 x l0~ 27 2. 32 x 10 12.03 3. 31 500 Aux. Ref 30 2. 84 x 10~ 23 1. 20 x 10 13. 23 3. 88 1 Cost = 6000 P0 ~ where P is input power in kilowatts. * Auxiliary refrigerator of appropriate capacity operating at 10 K. 62-332 ~ - 76 - 75 PAGENO="1186" 1180 Table 1. 3 Liquefaction/refrigeratiOn coats per unit of product cryogenic hydrogen (from gaseous hydrogen). Plant Size, kg/h 100,000 7,000 3,500 1,500 500 lb/h azo,462 15,430 7,716 3,307 1,100 Liquid Hydrogen Power Costs1 0. 119 $/kg 0. 136 $/kg 0. 140 $/kg 0. 144 $/kg 0. 159 $/kg O&M3 0. 013 0. 035 0. 045 0. 062 0. 097 Fixed Charges4 0.019 o* 0. 057 0. 075 0. 111 Total $/kg 0. 151 0. 216 0. 242 0. 281 0. 367 Total $/lb 0.068 0.098 0. 110 0. 127 0. 166 6 2 Total $/l0 Btu 1. 32 1. 90 2. 13 2. 46 3. 22 50-SO Slush Hydrogen Power Costs 0. 135 0. 154 0. 159 0. 164 0. 181 O&M 0. 014 0. 038 0. 049 0. 067 0. 106 Fixed Charges 0.020 0.049 0.062 0.082 0.122 Total $/kg 0. 169 0.241 0.270 0. 313 0.409 Total $/lb 0. 077 0. 109 0. 122 0. 142 0. 186 Total $/106 Btu 1.49 2. 11 2. 36 2.75 3. 60 Solid Hydrogen Power Costs 0. 146 0. 172 0. 177 0. 184 0. 206 O&M 0.018 0.041 0.053 0.072 0. 115 Fixed Charges 0.025 0.063 0.075 0.105 0.159 Total $/kg 0. 189 0. 276 0. 305 0. 361 0. 480 Total $/lb 0. 085 0. 125 0. 138 0. 164 0.218 Total $/106 Btu 1.65 2.42 2. 67 3. 18 4.22 1 Electric power costs $. 012/kW-h 2 Based on lower heating value of 33. 331 kW-h/kg (51, 600 Btu/lb) $/kg = 301. 88 (P/110372)°' 65/liquefaction rate; P = Input power,kW FCR = I (1~1)~/((1~1)~ - 1) I = Interest Rate, 15%; y = Plant life, 25 years PAGENO="1187" 1181 The cost of producing solid hydrogen was estimated as follows: First, liquid hydrogen is produced at the N.B.P. and then frozen solid with an auxiliary 10 K refrigerator. The final temperature of the solid is taken at the triple point temperature (13.803 K). Esti- mates of the time required to freeze hydrogen in various configurations are given in refer- ence 117]. Table 1.3 shows the cost per unit of product for various sized units. Power costs were based on electrical availability at 0.012 $/kW-h. Operating and maintenance (0 & N) costs per unit of product were calculated by P 0.65 301.88 CO&M - ~ll0372 x Production Rate, kg/h where P is the input power in kilowatts and the production rate is for 90 percent plant operating time. The constant (301.88) includes a correction for kilograms per hour. The equation is a modified version of an equation presented by Hallet 1181. The equation was modified by basing the O&N costs on the installed compressor power instead of the liquefaction rate. This alteration allowed the O&M costs to change with plant size and with changes in eff i- ciency and ideal work of production. The fixed charges on the capital investment (per unit of product) were determined by Capital Investment C =FCR*x FC Production Rate x 0.9 x hours/year The costs presented in table 1.3 are based on current technology and extrapolations of trends in efficiency. Improved technology could yield lower costs. The largest reduction in costs would result from improved efficiency in the liquefaction process. Improved efficiency would not only reduce power requirements but would also reduce the capital in- vestment and the related fixed costs and O&N costs. Table 1.4 shows the possible reduction in costs with improved efficiency in the liquefaction process for a plant capacity of 7000 kg/h. Also, since most existing plants are one-of-a-kind, further reduction in plant costs could be expected if many plants of equal size were constructed. Table 1.4 Effect of efficiency of liquefaction on product costs - (7000 kg/h) EFF. (%) 35 40 45 50 55 60 Power Coats $/kg 0.136 0.119 0.106 0.095 0.087 0.079 O&M $/kg 0.035 0.032 O.~J3O 0.028 0.026 0.025 Fixed Charges $/kg 0.045 0.041 0.038 0.035 0.033 0.031 Total $/kg 0.216 0.192 0.174 0.158 0.146 0.135 Total $/lb 0.098 0.087 0.079 0.072 0.066 0.061 Total $/l06 Btu 1.90 1.69 1.53 1.40 1.28 1.18 * See footnote 4 in table 1.3. PAGENO="1188" 1182 The liquefaction costs are high and are a deterrent to the adoption of liquid hydrogen as an energy carrier. The energy requirements for liquefaction are shown in a simple block diagram in figure 1.5. The top half of this figure shows an energy balance assuming no recovery of the liquefaction energy. The figure shows that for every kilowatt of chemical energy output in the form of liquid hydrogen, 1.298 kW of energy from chemical and electri- cal sources must be supplied. The lover diagram in figure 1.5 indicates the energy recover- able from the liquid as an energy output. The recovered energy and the liquefaction energy were estimated by using the ideal work of liquefaction at an efficiency of 40 percent for both processes. Figure 1.5 indicates the energy penalty one must pay for liquefying hydro- gen. In addition, liquid storage and handling evaporation losses could impose an additional energy penalty of 10 to 20 percent for reliquefaction; i.e., electrical energy require- ments may be as high as 0.358 kW in the diagram shown on figure 1.5. Thus, the energy and cost penalties incurred in liquefying hydrogen are significant, but we must remember that the fuel application dictates the choice of fuel physical state. Only in a total fuel system can we estimate overall energy conversion efficiencies and fuel economics. Even then, convenience and performance factors favor dense fuels and fre- quently outweigh cost and efficiency arguments. 1.4 HYDROGEN COST CREDITS Large scale production and liquefaction of hydrogen offers several by-products that could lower the cost of hydrogen as a fuel. These are oxygen, deuterium, and refrigera- tion potential, i.e., recovery of liquefaction energy. 1.4.1 Oxygen By-Product Credit For every kilogram of hydrogen produced from water there are eight kilograms of oxygen produced. Hence, when the hydrogen fuel industry matures, large quantities of oxygen will be available. The by-product value of oxygen could range anywhere between zero and the cost of oxygen obtained from air separation. In 1972, the average price for large quantities of oxygen from air plants was O.58G/lb (l.3c/kg)[l9]. (This cost excludes transmission costs because the air plants are situated near the consumers.) Figure 1.6 shows the effect of oxygen by-product credit on the selling price of hydrogen. Unless large new markets are found, the by-product value will be low because of the large oversupply. Possible large scale future markets for oxygen include sewage treatment [20] and paper processing [21]. To make by-product oxygen more competitive with oxygen from air plants, the source should be close to the consumer to minimize transmission costs. For a given volumetric flow rate, it costs roughly twice as much to pipeline oxygen gas as hydro- gen [22]. 1.4.2 Deuterium By-Product The natural abundance of the isotope deuteriumis roughly 0.015% that of hydrogen. To obtain deuterium, the U.S. Atomic Energy Cotnmission goes through the costly (in capital and in energy) process of distilling heavy water (020) from water. The heavy water is electrolyzed to produce deuterium. A more direct method, especially if liquid hydrogen is PAGENO="1189" Input Energy ________ = 1.236 Output Energy 1183 1.05 kW Total Output Energy FIGURE 1.5 Energy Requirements for Liquefaction of Hydrogen (Based on LHV) With and Without Recovery of Liquefaction Energy. Electrical Energy = 0.298 kW Input Energy ____________ = 1.298 Output Energy PAGENO="1190" FIGURE 1.6 Effect of Oxygen By-product Credit on the Cost of Hydrogen. (LHv) (HHV) 1.00 1.00 - 0.80 0.60 I- ~` 0.80 - LU C-) ,~0.60 0.40 - 0.20 - 1184 BY-PRODUCT CREDIT OF OXYGEN, ~/kg 0.25 0.50 0.75 1.00 1.25 1.50 1.75 0.12 .~u -~ LU 0.08 0.06 ~ 0.04 0.02 0.80 0.40 0.20 - 0 0 0.20 0.40 0.60 BY-PRODUCT CREDIT OF OXYGEN, ~/1b PAGENO="1191" 1185 required, is the low temperature distillation of deuterium from hydrogen 1231; this method is used in Europe. At present, there is little demand for deuterium outside of basic resesrch. However, this could change radically if the fusion reactor becomes a reality since the two most pro- mising fusion reactions use deuterium as a reactant [24]. It is difficult to predict how much credit could be given for deuterium. Two recent estimates [25,26] range between 1.8 and 3.5c/kg of hydrogen; this amounts to 10% or less of the estimated cost of producing hydrogen gas. 1.4.3 Recovery of Liquefaction Energy When liquid hydrogen is available but gaseous hydrogen at ambient temperature and pressure is desired, some of the liquefaction energy can be recovered. The amount of energy that can be recovered is no greater than the ideal work of liquefaction (3.971 ~h) as shown in table 1.1. Because the ideal liquefaction energy is approximately 10 percent of the chemical energy of the hydrogen, the recovery of the liquefaction energy will pro- bably not be economical in small systems. However, in large vaporizing facilities, the recoverable energy is significant, and several interesting recovery techniques may be employed. The simplest recovery technique utilizes a system as shown on figure 1.7. The liquid is pumped to a high pressure by a liquid pump, vaporized and heated to ambient temperature by receiving heat from the ambient, and then expanded isothermally back to ambient pressure. The net work from this system is the work output from the isothermal expander minus the shaft work into the liquid pump. Using the conditions of NBP equilibrium liquid hydrogen in the stcrage container, and 300 K sea level ambient conditions, the net work from the system is shown on figure 1.8 as a function of the pumped liquid pressure. The top curve on the figure shows the recovered work if the pump and expander are 100 percent efficient; the work recovery shown by the lower curve includes an adiabatic efficiency of 80 percent for the pump and 60 percent isothermal efficiency for the expander. Parahydrogen properties from [27] were used to perform the calculations. A similar work recovery calculation can be made for liquid oxygen. The results of such a calculation are shown in figure 1.9. Oxygen data from [28] were used in the cal- culation. A further refinement of the recovery technique would be to use the refrigeration available to precool air in an air separation plant instead of absorbing heat from the ambient. Although large quantities of oxygen are produced by electrolysis and the use of this oxygen will increase the efficiency of a power plant while reducing emissions, the cost of transporting oxygen to a remote site is seldom economical. However, by using the refrigeration energy available from liquid hydrogen, stoichiometric amounts of oxygen can be separated from air on-site with very little additional energy. The capital expense of the on-site air separation plant may be balanced by the reduction in coat of a steam generating plant because of a reduction in boiler complexity. Other by-products from the air separa- tion plant, such as neon and argon in the near future, and perhaps helium in the distant future could be used as cost credits for liquid hydrogen. PAGENO="1192" ire Gas Work, In Work, Out Net Work Work Out - Work In FIGURE 1.7 Schematic of Method to Recover Work from Compressed Liquid Hydrogen. Heat from the Surroundings ISOTHERMAL atm ambient PAGENO="1193" 100 200 500 600 COMPRESSED 110010 PRESSURE, atm 300 400 3600 3200 2800 2400 2000 1600 1200 800 2.0 1.5 0 ~L 1.0 9000 10,000 0 1000 2000 3000 4000 5000 6000 7000 COMPRESSED LIQUID PRESSURE, psia FIGURE 1.8 Work Recovery from Compressed Liqaid Hydrogen. 8000 PAGENO="1194" 50 100 250 300 500 1000 1500 2000 2500 3000 COMPRESSED LIQUID PRESSURE, psia FIGURE 1.9 Work Recovery from Compressed Liquid Oxygen I. ly3 0 COMPRESSED LIQUID PRESSURE, atm 150 200 Ideal Work 180 160 140 - ~ 120 ~ 100 80 60 40 - Pump Efficiency, 80% Expander Effficiency, 60% .10 .075 .050 3500 4000 4500 5000 I I I I i I I i I i I PAGENO="1195" 1189 The feasibility of using an air separation plant to produce gaseous oxygen for com- bustion with hydrogen can be demonstrated by comparing the work of separation of a stoichio- metric amount of oxygen with the energy available from vaporizing the liquid hydrogen. Combustion of hydrogen with oxygen proceeds according to H2 + 1/2 02 -~ H20. The ideal work of separation of the oxygen from the air is 52.2 W-h per kilogram of oxygen [29]. Since every kilogram of hydrogen burned requires eight kilograms of oxygen, the required separa- tion energy becomes 417.6 W-h per kilogram of hydrogen. Using the ideal liquefaction energy available from one atmosphere liquid hydrogen (3971 W-h/kg, table 1.1) no additional energy would be required to obtain the gaseous oxygen if the overall efficiency of the recovery system and separation process is (417.6/3971) x 100 = 10.5 percent efficient. The efficiency data [30] for several nitrogen, air, and separation plants are included on figure 1.10. Percent Carnot refers to the ratio, w. N = x 100 where W is the work expenditure, subscript i indicates ideal work, and subscript a indicates the actual work requirement of the separator. The solid line was drawn to show average per- formance demonstrated by existing refrigerators and single fluid liquefiers. Data for re- frigeration units operating in the 30 to 90 K temperature range are shown by the open symbols; data for air separation and liquefaction plants are given by the symbols with an enclosed number. Unit 1 is a mobile liquid oxygen-nitrogen generator currently being used by the Navy and Marine Corps; units 2, 3, and 4 are liquid nitrogen generators; unit 5 is a small liquid oxygen generator; and unit 6 produces gaseous nitrogen at room temperature plus a small amount of liquid nitrogen--both products being delivered at about 0.8 MPa (8 atm) absolute pressure. It is apparent that efficiencies of 30 to 40 percent could be expected from large separation plants. Assuming 40 percent efficiency for the air separation cycle, the work required per kilogram of hydrogen to produce a stoichiometric amount of gaseous oxygen would be 417.6 W-h/0.4 - 1.044 kW-h per kilogram of evaporated hydrogen. Recovery of 30 percent of the ideal work of hydrogen liquefaction (3.971 1S~ would provide the energy required to produce this oxygen. Also, we can compare this energy requirement for production of oxygen from air with the energy available in compressed liquid hydrogen. Figure 1.8 indicates that recovery of work from compressed liquid hydrogen could supply enough energy to produce stoichiometric gaseous oxygen from air. A more detailed design analysis is necessary to prove this simple analysis, but the increased efficiency of having both oxygen and hydrogen available at a site remote from a liquid hydrogen generator may prove to be economically and environmentally attractive. PAGENO="1196" 10 Capacity, Watts Figure 1.10 Efficiency of Selected Low Temperature Refrigerators and Liquefiers. 10 0 0 U 0 a U a) 10_i io6 PAGENO="1197" 1191 1.5 REFERENCES [1] Faith, W. L., Keyes, D. B., and Clark, R. L., Industrial Chemicals, p. 434 (John Wiley & Sons, Inc., New York, N.Y., 1965). [2] Quade, R. N., and McMain, N. T. Jr., Hydrogen Production with a High Temperature Gas-cooled Reactor (HTGR), Paper presented at The Hydrogen Economy Miami Energy Conference, Miami Beach, Florida (March 18-20, 1974). [3] Katell, S., U.S. Bureau of Mines, Morgantown, West Virginia, personal communica- tion to the author (1973). [4] Harper, W. B., U.S. Bureau of Mines, Arlington, Virginia, personal communication to the author (1974). [5] Kincaide, W. C., and Williams, C. F., Storage of Electrical Energy Through Electrolysis, paper presented at the 8th IECEC, Philadelphia, Pennsylvania (August 1973). [6] Nutall, L. J., Fickett, A. P., and Titterington, W. A., Hydrogen Generation by Solid Polymer Electrolyte Water Electrolysis, paper presented at The Hydrogen Economy Miami Energy Conference, Miami Beach, Florida (March 18-20, 1974). [7] Kincaide, W. C., Teledyne Isotopes, Timonium, Maryland, personal communication to the author (1973). [8] Funk, J. E., and Reinstrom, R. M., Energy Requirements in the Production of Hydrogen from Water, md. Eng. Chem. Proc. Des. Develop. 5, 336 (July 1966). [9] Russell, J. 1., and ?orter, J. T., A Search for Thermochemical Water-splitting Cycles, paper presented at The Hydrogen Economy Miami Energy Conference, Miami Beach, Florida (March 18-20, 1974). [10] Funk, J. E., Conger, W. L., and Carty, R. H., Evaluation of Multi-step Thermo- chemical Processes for the Production of Hydrogen from Water, ibid. [11] Wentorf, K. H., Jr., and Han~eman, R. E., Thermochemical Hydrogen Generation, Science 185, No. 4148, 311 (July 1974). [12] Chao, K. K., and Cox, K. E., An Analysis of Hydrogen Production via Closed-cycle Schemes, paper presented at The Hydrogen Economy Miami Energy Conference, Miami Beach, Florida (March 18-20, 1974). [13] Eaatlund, B. J., and Gough, W. C., Generation of Hydrogen by Ultra-violet Light Produced by the Fusion Torch, paper presented at the 163rd American Chemical Society Meeting, Boston, Massachusetts (April 9-14, 1972). [14] Mitsui, A., Utilization of Solar En~rgy for Hydrogen Production by Cell Free System of Photosynthetic Organisms, paper presented at The Hydrogen Economy Miami Energy Conference, Miami Beach, Florida (March 18-20, 1974). [15] Strobridge, T. R., Cryogenic Refrigerators - An Updated Survey, Nat. Bur. Stand. (U.S.) Tech. Note 655 (June 1974). [16] Sindt, C. F., A Summary of the Characterization Study of Slush Hydrogen, Cryogenics 10, 372 (October 1970). [17] Daney, D. E., Steward, W. G., and Voth, R. 0., Preliminary Hydrogen Freezing Studies, Nat. Bur. Stand. (U.S.) IR Report 73-339 (October 1973). [18] Hallett, N. C., Study, Cost, and System Analysis of Liquid Hydrogen Production, NASA Report CR-73226 (1968). PAGENO="1198" 1192 [19] Pennington, .1. W., Bureau of Hines, Washington, D.C., personal communication to the author (1974). [20] Rosen, H. H., Use of Ozone and Oxygen in Advanced Waste Water Treatment, J. Water Pollution Control Fed. 45, Ho. 12, 2521 (December 1973). [21] Chem. & Eng. News, Pulp Hill Gets its Own Oxygen Generator, 52, No. 29, 15 (July 22, 1974). [22] Bighi, G., Dejace, J., Massard, C., and Ciborra, B., Economics of Pipeline Transport for Hydrogen and Oxygen, paper presented at The Hydrogen Economy Miami Energy Conference, Miami Beach, Florida (March 18, 1974). [23] Flynn, T. H., Pilot Plant Data for Hydrogen Isotope Distillation, Chem. Eng. Progr. 56, No. 3, 37 (March 1960). [24] Gough, W. C., and Eastlund, R. J., The Prospects of Fusion Power, Sci. Amer. 224, No. 2, 50 (February 1971). [25] Stuart, A. K., Modern Electrolyzer Technology, paper presented at the 163rd National Meeting of the American Chemical Society, Boston, Massachusetts (April 9, 1972). [26] DeBeni, G., and Harchetti, C., A Chemical Process to Decompose Water Using Nuclear Heat, paper presented at the 163rd National Meeting of the American Chemical Society, Boston, Massachusetts (April 9, 1973). [27] McCarty, K. D., and Weber, L. A., Thernophysical Properties of Parahydrogen from the Freezing Liquic Line to 5000 R for Pressures to 10,000 PSIA, Nat. Bur. Stand. (U.S.) Tech. Note 617 (April 1972). [28] McCarty, R. D., and Weber, L. A., Thermophysical Properties of Oxygen from the Freezing Liquid Line to 600 R for Pressures to 5000 PSIA, Nat. Bur. Stand. (U.S.) Tech. Note 384 (July 1971). [29) Barron, R., Cryogenic Systems, p. 188 (McGraw Hill Book Company, New York, New York, 1966). [30] Arnett, R. W., and Muhlenhaupt, R. C., Study of Oxygen and Nitrogen Generating Systems, Unpublished NBS Report (September 1970). PAGENO="1199" 1193 - CHAPTER 2 HYDROGEN IN THE ELECTRICAL UTILITY INDUSTRY W. R. Parrish 2.0 SUMMARY This chapter considers the economic feasibility of using hydrogen as a fuel in peaking and intermediate power generation. To make the study meaningful, hydrogen was compared with other reasonable alternatives. The alternatives fall into two categories -- power generation and energy storage. In power generation we consider using gas turbines, fuel cells and combined cycle units. Where- as the first two are considered for both peaking and intermediate duty, the combined cycle is considered for intermediate duty only. The fuels considered were hydrogen, synthetic natural gas (SNG) and methanol. We evaluate the relative merits of two sources of hydrogen: 1) hydrogen produced via electrolysis using off-peak power and 2) hydrogen purchased from an outside source. Methods of storing hydrogen include liquid, compressed gas and metal hydride. Storage methods for SNG include liquid and compressed gas while methanol is readily storable as a liquid. We evaluate three energy storage concepts: hydro pumped storage, batteries and super- conducting magnetic energy storage (SMES). A simplified approach to the economic analysis is used wherein we assume that sufficient off-peak power is available and that power production costs consist of fuel costs (some- times off-peak power costs must be considered instead of, or in addition to, fuel costs), operating and maintenance costs, and fixed charges on capital investment. Sample calcula- tions are given in Appendix A. All cost data required for the analysis are based on current costs or currently anticipated costs; for several cases we give estimated cost ranges. For the economic comparison, we consider a 100 MWe peaking unit and a 400 MWe inter- mediate unit. In each case we report both total and component power production costs. This allows one to rapidly determine the effect of changing any cost factor used in the base case calculations. The economic analysis based on the assumptions described below indicates that for peaking operation, pumped storage and methanol-fired gas turbines are currently the most attractive options while batteries and SMES are the least attractive. SNG looks slightly more economical than purchased hydrogen, which, in turn looks slightly more economical than electrolytic hydrogen. The predominant cost in all of the alternatives is the fixed charge on capital. The most attractive physical form of fuel storage appears to be liquid although underground gas storage might be competitive if depleted gas fields are available. The above conclusions also apply to intermediate operation except that the most attractive means of generating power is the combined cycle unit using methanol. One must remember that the results presented here are based on present day and antici- pated near-future technology. Significant technological advances could radically alter these conclusions. Also other cost-influencing factors such as stricter environmental controls could make hydrogen an attractive fuel for future power generation. PAGENO="1200" 1194 2.1 INTRODUCTION The electrical utilities must meet daily load variations where the peak demand can be more than twice the minimum demand [1]; figure 2.1 illustrates a typical daily load curve. The exact shape of the curve depends upon the weather and the relative demand of residential and industrial consumers. However, all utilities are faced with the problem of having to meet high demands for relative short periods of time. This is shown more clearly by the annual duration curve in figure 2.2. This curve indicates how many hours per year the utility operates at or above a given power level. Utilities normally divide the curve into three regions. Base load plants have high capital costs and high thermal efficiencies N40% for fossil-fired plants based on higher heating value (HHV)] but rela- tively low operating and fuel costs. To minimize power production costs, these plants must be operated 7000 hours or more per year. Base load plants use either fossil fuels, such as coal and oil, or nuclear fuel (there are base load hydro-electric plants in some areas). Plant sizes range from 200 to 1400 MW. The intermediate demand is met by pumped hydro-storage and fossil-fired steam plants with variable duty cycles [2]. Combined cycle units which use premium fuels are also used for intermediate loadings. Plant capacities vary between 100 and 500 MW, and they operate between 1000 and 4000 hours per year. The peaking portion of the curve is supplied predominantly by gas turbines and smaller, old fossil-fired plants with capacities of 200 MW or less [2]. Peaking units are character- ized by low capital costs but relatively high operating and fuel costs. Annual operating time is usually less than 1000 hours; while the fossil plants can use a variety of fuels, gas turbines must use expensive premium fuels such as low-sulfur fuel oil and natural gas. In the next decade, the petroleum shortage will grossly affect the electrical power industry. There will be more nuclear base load plants [3], and fossil-fired plants will return to coal or convert to gas produced from coal [4]. Intermediate plants will also depend more heavily on coal. However, peaking units, especially if they are gas turbines, will continue using premium ~üels. This chapter considers the economics of some alternatives for peak and intermediate power generation. A study of this kind not only points out which alternatives are the most attractive, but it also picks out the major cost items of each alternative; this gives a guide to where technological improvements would be most profitable. Several papers discuss various peaking alternatives, but the report by Kyle, et al. [5] is probably the most com- prehensive to date. However, they did not consider fuel cells, superconducting magnetic energy storage or possible synthetic fuels. To our knowledge, there are no comparable studies for intermediate loading. Table 2.1 lists the alternatives considered here. The options fall into two broad categories--power generation and energy storage. Power generating alternatives considered include gas turbines and fuel cells for peaking and intermediate operation; combined cycle units are considered for intermediate loading only. We investigate three chemical fuels--hydrogen, synthetic natural gas (SNG) and methanol. It is assumed that hydrogen can be made on site via electrolysis of water or PAGENO="1201" 1195 100 80 ~ 60 ~ 40 20 12 6 AM 12 6 PM HOURS FIGURE 2.1: Typical Daily Load Curve 12 62-332 0 - 76 - 76 PAGENO="1202" 1196 Peaking 100 go 80 70 ~ 60 C O 50 °- 40 30 20 10 0 0 2000 4000 6000 TIME, hours FIGURE 2.2: Typical Annual Load Duration Curse 8760 PAGENO="1203" 1197 Table 2.1 Peaking and Intermediate Power Plant Alternatives Considered in this Paper UNIT FUEL ENERGY STORAGE MEDIA Gas Turbines OR Fuel Cells OR Combined Cycle (Intermediate Duty Only) Hydrogen: Electrolytic H2, H from Coal or T~ermochemical Decomposition of H2O Liquid Hydrogen Compressed Gaseous Hydrogen Metal Hydride SNG (from Coal) Liquid SNG Compressed Gaseous SNG Methamol (from Coal) Liquid Methanol Hydro Pumped Storage OR Batteries OR Superconducting Magnetic Energy Storage (SMES) Off-Peak Electricity Potential Energy Electrochemical Energy Electromagüetic Energy PAGENO="1204" 1198 be bought f ron the outside. In the latter case, we assume the hydrogen may be produced from coal or by thermochemical decomposition of water using nuclear reactor heat. It is assumed that both SNG and methanol are produced from coal. The compressed gas concept uses off-peak electricity to drive a centrifugal compressor for pressurizing the storage vessel. When the unit is producing power, the gaseous fuel depressurizes through the compressor, making an electric motor a generator. Thus, some of the energy used to store the gas can be recovered; this reduces the total fuel requirement. Energy storage systems considered include hydropumped storage, batteries and super- conducting magnetic energy storage (SMES). We include pumped storage as a base case be- cause it is the way some utilities store off-peak power today. No attempt has been made to cover all of the possible ways of storing off-peak power. Two alternatives, briefly considered, appeared to be economically unattractive; these are capacitors and flywheels [61. However, a recent article [7] gives some cost estimates for flywheels which make them more appealing if high strength, low cost materials become available. One alternative studied by Korsmeyer [8] not considered here which might prove attrac- tive is coop teased air storage in combination with gas turbines - Air is compressed using of f-peak power; then during turbine operation, the air is fed directly to the turbine. This would increase turbine efficiency by roughly 250% because a large portion of the energy generated by the turbine normally is used to compress the inlet air. Korsmeyer found large variations in estimated capital costs, especially mining costs. However, if the proper underground sites could be found for compressed air storage, this concept may significantly reduce peaking power costs. Many variables affect power production costs, and we consider the influence of the following parameters: 1. unit size, 2. off-peak power costs, 3. fuel costs, and 4. equipment capital costs. The parameters are varied over plausible ranges; in some cases, capital costs are considered from the standpoint of break-even charts. Finally, there may be advantage to locating power units close to load centers [2,5]. Therefore, transmission credits can affect the relative attractiveness of the alternatives as shown herein. 2.2 ECONOMIC ANALYSIS We take a simplistic approach in evaluating the economic feasibility of the various alternatives because each utility company is unique in demand requirements and in the make-up of generating components. Also, many of the cost data are too uncertain to justify a sophisticated analysis. (Appendix A gives sample calculations.) 2.2.1 Basic Assumptions We assume that off-peak power is readily available within the distribution network for at least eight hours per day; this makes the type of base load plant immaterial in this PAGENO="1205" 1199 study. It should be pointed out that the eight hours per day of off-peak power is realistic today but there may be less off-peak power in the future. We assume that power production costs include three components: 1. fuel and/or off-peak power costs, 2. operating and maintenance costs (0 & M), and 3. fixed charges on capital investment. Fuel and power costs are simple functions of conversion efficiency. 0 & N costs include all maintenance, labor and operating costs, excluding fuel costs. Fixed charges cover taxes, depreciation, cost of capital, and return on investment. We calculate fixed charges using a capital recovery factor (which converts the initial capital cost to a series of equal annual payments) with a fixed charge rate of l5%/yr; this corresponds to an investor owned company [9]. To size the various components, we assume that the peaking and intermediate units must have the capacity to operate 10 and 16 hours per day, respectively. This method of estimat- ing the capacity of an energy storage unit weighs heavily against those techniques with high capital costs. The reserve capacity is almost double the actual daily useage. In the case where a fuel is being produced and/or liquefied for storage, the flow rate is taken to be 75% of the maximum daily demand. This assumes that the remaining 25% can be made up during weekends when the demand is lower. Finally, the cost of land is omitted and the working capital is considered negligible in terms of capital costs. 2.3 COST DATA 2.3.1 Power Generation Units Table 2.2 lists the necessary cost data f or the power generation units considered here. All costs are given in 1973 dollars. Gas turbine and combined cycle data are based on current operating technology [10]. We assume that turbine costs are independent of the fuel considered here. Table 2.2 Cost Data for Power Generation Units Capital Cost 0 & M Plant Life Efficiency $/kWe mills/kW-h Yrs. Unit Gas Turbine 135 [lOJ Fuel Cell 140290b ~ DC-AC Inverter 45 [10] Reformer 25 1121 Combined Cycle 200[l01 a. Efficiency is based on LHV b. This is the cost of the fuel cell only. Ref. [12] gives costs of fuel cells plus inverters and reformer. 3. 4 [10] 20 28~ [10] 1.5 [11] 16, 000 HRS [12] 51a [12] -- 20 [11] 97 [13] -- lO[ll] 85 [11] 2.l[1O] 20 41a[101 PAGENO="1206" 1200 Fuel cell cost data are more uncertain because fuel cells have not been used by utility companies although they are supporting fuel cell development [11,121. Since fuel cells pro- duce DC power, DC-AC inverters are needed. The fuel cells being developed for utility appli- cations use hydrogen and air [11]. Therefore, unless hydrogen is the fuel, a catalytic re- former is necessary to produce hydrogen from another fuel. 2.3.2 Fuel Production and Storage Table 2.3 lists the economic data used in evaluating the economic feasibility of various fuels and storage schemes. The primary means of producing hydrogen today is either steam reforming or partial oxidation of fossil fuels such as natural gas and naphtha [12]. As these feedstocks be- come more expensive and in shorter supply, coal will become the major source of hydrogen. Also, thermochemical decomposition of water [14,15] using nuclear heat may become economically attractive. The anticipated price range for hydrogen from these processes is 1.15 [161 to 1.55 $/MBTIJ* (HHV) [14]. The lower cost corresponds to hydrogen from coal at 4$/ton; if coal costs 6$/ton, hydrogen would sell at l.30$IMBTIJ. Electrolytic hydrogen masts depend primarily on power costs [17]; considering only power cost, electrolytic hydrogen costs 4.70$/METU if power costs 15 mills/kW-h. However, if off-peak power is available at less than 5 mills/kW-h electrolytic hydrogen becomes more competitive. We use the cost data of Kincaide and Williams [17] for the electrolysis plant. In their work, they used equipment currently available which put a limit on component size. This makes the capital cost increase linearly with capacity. We assume that larger com- ponents will become available as needed because increasing sizes should not cause major technological problems. Hence, we assume that costs increase with size to the 0.8 power. The capital costs are based on a 10 ton/day plant with 33% utilization and an advanced cell design. As Kincaide and Williams point out, the optimum plant design depends upon power costs; this consideration is deglected here. Of the three options for storing hydrogen, only cryogenic storage can be considered state-of-the-art for storing the quantities that would be required for utility applications. Liquefaction costs are from Hallett [18]; they have been increased 25% to account for in- flation. The cryogenic storage cost is for an above-ground, double wall tank with evacuated perlite insulation [18]. This container has a boil-off rate of less than 0.1% per day. If higher boil-off rates are acceptable (2% per day), vessel costs can be cut by 60% [18]. The storage vessel is sized to hold three days supply of electrolytic hydrogen; storage vessels for the other fuels are sized to hold a ten day supply. The centrifugal compressor cost for high pressure storage is estimated using Guthrie's [19] cost data. To size the compressor, we assume that it has a 60% efficiency, based on isothermal compression. In all the compressed gas storage calculations, we assume ideal gas behavior. The lower vessel cost is for depleted gas fields [20]; the higher cost is for above ground storage in 10 ft long by 10 ft diameter cylindrical pressure vessels [19]. We assume that the maximum pressure in underground storage is 1000 psia, and * MBTU = 106 BTU throughout this chapter. PAGENO="1207" High Preocure Vessel Hydride Storage Fuel Coot $/MBTUa SNG Production Coal 1. 00 [23]_l. 55 Storage Liquefaction Cryogenic Storage Coenpree sed Gas METHANOL Production Coal Storage Plant Life Power Consumption Yro kW'hellb of Fuel a, Coot booed on HHV of fuel; higher and lower heating alues in BTU/lb, used in theoe ca lculati non are: HHV LHV H2 61,030 51,570 SNG 23. 880 21,520 Methanol 9, 760 8, 680 Table 2.3 Coot Data for Fuel Production and Storage Capital o 8, M Coot, K$ K$/Yr HYDROGEN Production Coal or Thermo- chescucal decomposition Electrolysis Storage Liquefaction Cryogenic Storage Compressed Gas Storage 1. 15 [16] 1. 55 [14] 930(lbfhr/833)°' 88 [17] 39400-(lb/hr/20833)O. 8 [18] 925 `(lh/6x10°)°' 90 [18] 840'(HP/1000)0. 82 [19] 0. 06 [20] - 10. 50 $/ft3 [19] 0. 50-1. 00 $/lh FeTi [21] (See Text) 25 [17] 20 [18] 20 20 25 25 19.0 [17] 4. 5 [18] 60% of isothermal 0. 88 [21] 0. 01 $116 H2 [17] 2380 -)lb/hr/ 20833)0 65 [18] 2% of capital coot per year 5% of capital coot per year 1% of capital coot per year 3 millo/kW-h 5% of capital coot per year 2% of capital coot per year 3% of capital coot per year 7980. (lb/hr/l0602)°' 56 [24] 6. 61116 [25] Same as Compreosed Gao Storage for H2 1. 00 [26]-l. 50 53. 6 (lb/658000)~ 63 [19] 25 1. 1 [20] 25 25 b_ Uoing the 0. 8 exponent moles certain aooumptiono, see text. PAGENO="1208" 1202 in aboveground storage, it is 2400 psia. To account for the added wall thickness of the pressure vessel, the vessel cost is increased by 15% of the base cost for each 100 psi of operating pressure [19]. Costs for hydride storage [21] are speculative because they are based on an as yet untested design. The process consists of the metal hydride unit operating at 35 atm and using hydrogen as the heat transfer fluid during charging and discharging. The estimated capital cost depends upon charging and discharging rate as well as the amount of hydrogen stored. Assuming iron titanium costs l$/lb, it amounts to between 50 and 65% of the total hydride storage cost in peaking operation and even higher (70 to 80%) in intermediate duty. (See Appendix B for details of hydride storage costs). Hydride storage requires some power to drive compressors and pumps; this power demand is given in Table 2.3. The system also needs some thermal energy ( 2000 BTU per pound of H2 discharged) to heat the bed during discharging; we assume that waste heat is readily available at no charge for heating the bed. Projected costs for making SNG from coal vary, but we anticipate that the selling price will be somewhere between 1.00 [23] and 1.50 $/NBTU (HHV). As in the case of hydrogen, storage of SNG requires cryogenic processing. Liquefaction capital cost is based on Wenzel's [24] data for LNG peakshaving plants. The cryogenic container capital cost corresponds to an all steel, 600,000 barrel tank currently under construction [25]. We assume the capital cost per unit of container volume of compressed gas storage to be the same for both hydrogen and SNG. For equivalent energy storage at the same storage pressure, hydrogen requires larger containers and more compressor power than SNG. The selling price of methanol from coal will probably be in the range of 1.00 [26] to 1.50 $/MBTIJ (WHy). Of the three fuels considered, methanol is the simplest and cheapest to store. The storage capital cost is for cone roofed, carbon steel tanks [19]. 2.3.3 Energy Storage Systems Table 2.4 lists the cost data for the three energy storage systems considered here. The range in capital cost for pumped storage covers what a new facility might cost; costs above 250 $/kW make pumped storage unattractive [9]. Development in new types of batteries make their capital cost uncertain. The higher cost represents costs for present-day lead-acid batteries while the lower cost corresponds to the target selling price for lithium-sulfur batteries [5]. Battery life is based on lead-acid batteries [2]; future batteries might last 7 to 8 years [5] which would make them much more attractive. The total cost of a battery system must include a DC-AC inverter. Superconducting magnetic energy storage technology is in its infancy; therefore, all cost data for SMES systems must be considered preliminary. Capital costs are based on 10.8 GWh of energy storage [27]. The capital cost depends upon the magnet geometry, solenoidal or toroidal, and the reinforcement, warm or cold. The solenoidal geometry is less expensive because it stores more energy per unit of superconductor than does the torus; depending upon the system, superconductor costs are between 20 to 35% of the total SMES cost. We assume 0 & H costs for SMES to be comparable to those of pumped storage. PAGENO="1209" 1203 Table 2.4 Cost Data for Energy Storage Systems Capital Cost 0 & M Plant Life Efficiency $/kW-he mills/kW-he Yrs a. To obtain the total capital cost, the cost of a DC-AC inverter must be included (see Table 2.2). 2.4 ECONOMIC COMPARISON 2.4.1 Peaking Units Table 2.5 lists the cost of producing peak power for the various alternatives. For ease of comparison, all three fuels are assumed to cost 1.25 $/MBTU (HHV). Tables 2.6, 2.7 and 2.8 present the component costs used to obtain Table 2.5. Using these supplemental tables and simple ratios, one can quickly estimate the effect of a component cost change on the total power cost. The effect of size is more complicated in many cases because costs are non-linear functions of capacity. Based on Table 2.5, the least expensive ways to produce peak power are by using 1) pumped storage and 2) gas turbines using methanol as the fuel. Therefore, to make any of the other options competitive, costs must be lowered enough to reduce production costs to around 40 mills/kW-h if annual operating time is 1000 hours. Considering the remaining energy storage systems first, we want to determine how they can be made competitive. For these discussions, we will hold plant size, operating time, and fixed charge rate constant. The remaining para~seters affecting power coste for batteries and SMES are off peak power costs, capital costs, and transmission credits, i.e., credit for locating the units near load centers [2]. A simple calculation shows that to make batteries competitive, they must cost between 10 and 15 $/kW-h; this as~umes reasonable off-peak power (< 20 mills/kW-h) and transmission credits (< 50 $/kW which corresponds to an 8 mills/kW-h credit for this case). Batteries could be competitive at 15 to 20 $/kW-h if battery life can be extended from five to eight years. Using the same ranges of off-peak power costs and transmission credits, SMES capital costs would have to be around 15 to 20 $/kW-h before they could produce peak power at 40 mills/kW-h. The nearest competitor to the methanol gas turbine option is the methanol fuel cell system. Peak power costs are higher for the fuel cell systems using methanol or SNG be- cause the fuel savings cannot offset the higher capital costs of the reformer-fuel cell- inverter system. Direct comparison of methanol-fueled gas turbine and fuel cell systems Unit Hydro Pumped Storage 200 $/kW 2 [9] 50 6'[9J Batteries 20 - 50a [5] 1 [2] 5 [2] 70 [5] Superconducting Magnetic Energy 70 - 150a [27] 2 20 95 [13] Storage PAGENO="1210" 1204 Table 2.5 Base Case Peaking Power Costs, miils/kW-h Capacity 100 MW Operating Time 1000 h/yr Cost of Off-Peak Power 5 mills/kW-h POWER GENERATING UNITS Gas Fuel Fuel Storage Turbines Ceilsa Hydrogen (ci.) Liquid 144. 0 130. 3 Comp. Gas A.G.b 29300 15500 U.G. 144.1 128.3 Hydride 153, 8 135. 0 Hydrogen (@ 1. 25 $/MBTU) Liquid 117. 9 114.4 Comp. Gas A.G. 97400 51500 U. G. 262.4 198.3 Hydride 244. 8 186. 0 SNG (@ 1. 25 S/MBTU) Liquid 85. 9 107. 8 Comp. Gas A.G. 28900 19700 U.G. 119.2 124.7 Methanol (@ 1. 25 $/MBTU) Liquid 42. 8 74. 2 ENERGY STORAGE SYSTEMS (1000 MW-h CAPACITY) Pumped Storage 39.5 Batteriesc 164.5 SMESd 254.1 a. Assumes fuel cell cost is 290 S/kW. b. A. G. denotes above ground storage; U. G. denotes underground storage in a depleted oil or gas field. c. Assumes batteries cost 50 $/kW-h. d. Assumes SMES cost 150 $/kW-h. PAGENO="1211" 1205 Table 2.6a Component Peaking Power Costs for Hydrogen Fueled Systems Using Liquid or Hydride Storage Capital Operating Costs, mills/kW-h Component Cost, K$ Fixed Chargesb 0 & M Fuel/Elec. GTa FC GT FC GT FC GT FC Power Generator 13500 33500 21. 6 55. 9 3. 4 1. 5 Electrolysis Plant 12800 8070 19. 8 12. 5 2. 4 1. 3 22. 4 12. 6 Fuel Cost @ 1. 25 MBTU 18. 0 10. 1 Cryogenic Storage Liquefier 41400 26000 66. 1 41. 6 2. 5 1. 7 5. 3 3. 0 Storage Tank 3 days storage 10 days storage 267 583 183 400 0. 4 0. 9 0. 3 0.6 0. 0 0. 1 0. 0 0. 0 . Hydride Storage 3 days storage 10 days storage 51800 127800 30800 74300 80. 1 197.8 47. 7 115.9 3. 0 3.0 3. 0 3.0 1. 0 1.0 0. 6 0.6 a. GT = gas turbine, FC = fue I cell . b. Fixed charges are calculated using capital recovery factor (fraction/yr) X Capital Cost ($)/Power (MW) / Operating time (h/yr) where the capital recovery factor is given by FCR (1 + FCR)PL/{(l + FCR)PL - 1] and FCR is the fixed charge rate and PL is plant life in years. Table 2.6b Component Peaking Power Costs for Hydrogen Fueled Systems Using Compressed Gas Storage Capital Operating Costs, mills/kW-h Component Cost, K$ Fixed Charges 0 & M Fuel/Elec. GT FC CT FC CT FC GT FC Main Power Generator lO700a 25300 17. 1 48. 8 2. 7 1. 3 Electrolysis Plant 10700 7200 16. 5 11. 2 1. 9 1. 2 17. 8 11. 0 Fuel Cost @ 1.25 $/MBTU 14. 3 8. 8 Compressor-Turbine 12000 8100 19. 2 12. 9 6. 0 4. 0 2. 9 1. 8 Storage Above Ground 3 days storage l3x109$ 7. lxlO9$ 20850 11700 1350 712 10 days storage 45xl 09$ 23xl09$ 69500 36700 4500 2370 Underg round 3 days storage 36500 22000 56. 4 34. 0 3. 6 2. 2 10 days storage 121500 73200 188. 0 113. 3 12. 2 7. 3 a. All costs, except where noted,are for underground storage. PAGENO="1212" 1206 Table 2.7a Component Prakiog Poser Costs for SNG & Methanol Fueled Systems tJoissg Liquid Storage Capital Operating Costs. snitls/kW-h Cost. KS Fined Charges 0 & M Fuel/Elen. GT FC GT FC GT FC GT FC 13500 36000 21.6 60.9 3.4 1.5 Component Pomer Generator SF0 Fuel Cost 16. 9 11. 1 @ 1.25 $/MBTU Cryogenin Storage 15600 30. 4 24. 1 9. 8 7. 8 3. 1 2. 0 Liquefier Storage Tank 340 220 0. 5 0. 4 0. 1 0. 0 Methanol Fuel Cost 17. 1 11. 3 @ 1. 25 $/MBTU Storage Tanls 360 270 0. 6 0. 6 0. 1 0. 1 Table 2. ta Component Peaking Psuer Costs for SNG Fueled Systems Ussssg Compressed Gas Storage Capital Operating Costs, mills/kWh Component Cost, KS Fined Charges 0 & M Fuel/Elec. FC GT FC GT FC GT FC GT Main Poser 57. 3. 2 1. 4 Generator 12550a 36000 20. 0 Fuel Cost 15. 7 10.6 @ 1.25 $/MBTU 1.0 0.7 Compretsor-Tssrbine 5100 370S 8.2 5.9 Storage Ab oregrmsnd l3x1095 9. 0xlS~S 20600 14000 1300 904 4. 2 2. 8 Undergs'our.d 41600 28200 64. 5 43. 6 All sosts, encept tchere noted, are for underground storage. Table 2.8 Component Poser Costs for Peaking Energy Storage Systems Operating Costs, mille/bW-h Capital Fined 0 & M Elec. Component Cost, K$ Charges Pumped Storage 20000 30. 0 2. 0 7. 5 Bsttertes 54500 156. 4 1. 0 7. 1 SMES 154500 246.8 2.0 5.3 PAGENO="1213" 1207 200 - FUEL CELL TRANSMISSION CREDIT, $/kW 50 V) L) -J ~ 100 L) -J L) -J LU U- NOTE: Gas Turbine allowed zero Transmi ssion Credit. 0 0 1.00 2.00 METHANOL FUEL COST, $/MBTU(HHv) FIGURE 2.3: Fuel Cell Capital Cost Required to Make Fuel Cells Competitive With Gas Turbines. PAGENO="1214" 1208 gives break-even capital costs for fuel cells as shown on figure 2.3. The curves are based on gas turbine cost and efficiency remaining constant. Under the stated assumptions, none of the remaining alternatives look promising for peak operations unless methanol costs over 3 $/MBTU. This is due to the high capital costs required for each alternative. Also, the equipment runs at roughly 30% of full capacity on an annual basis (assuming the units operate 8 instead of 24 hours per day). One alternative for the electrolytic hydrogen concept would be to run the electrolysis unit and liquefier at full capacity for 8 hours per day and sell the excess hydrogen. Considering the gas turbine option, a selling price of roughly 7 $/MBTU (including 1.90 $/MBTU for electricity at 5 mills/kW-h) would be required to make this option competitive with pumped storage.' However, the break-even selling price can be lowered by increasing plant capacity if there is sufficient off-peak power. Figure 2.4 shows the break-even selling price of gaseous hydrogen as a function of off-peak power cost and plant capacity factor. The plant capacity factor is the ratio of actual plant capacity to the base case capacity (2.2 x l0~ lbs/hr for this case). The liquefier capacity remained constant in these calculations. Figure 2.5 shows break-even prices for producing liquid hydrogen. The same type of calculations for fuel cells using electrolytic hydrogen shows that the break-even selling prices are roughly 2 $/MBTU higher than in the gas turbine case. This is caused by the high capital cost of the fuel cells and by the lower amount of excess hydrogen per kW-h output resulting from the fuel cells higher efficiency. Considering storage techniques for hydrogen and SNG, cryogenic storage appears to be the most attractive while compressed gas storage in pressure vessels is the least attractive (at least at pressures less than 2400 psia). Hydride storage, assuming iron-titanium costs 1 $/lb, is more expensive than liquid storage if many days of fuel must be stored. If the cost of iron titanium drops to 0.50 s/lb [28], and if we store three days supply of hydrogen, hydride storage becomes competitive with liquid storage. On the other hand, no allowance has been made for recovery of the energy used in liquefaction while dehydriding energy was taken at zero cost. For example, it might be possible to use cold hydrogen gas to reduce the work required to compress the air fed to the gas turbine. As in the compressed air concept, this would increase turbine efficiency. However, it still would not make hydrogen competitive with methanol (at currently estimated costs of producing methanol from coal). In the above discussions, we assumed plant capacity to be constant. Changing plant capacity does not alter the results; in using this simple analysis, peak power costs are independent of capacity for the energy storage systems and the methanol systems. Peak power costs for the other alternatives decrease slightly (< 10%) when plant capacity is doubled. The major effect of increased off-peak power cost is to make electrolytic hydrogen and the energy storage techniques look less attractive. To a lesser extent, it would de- crease the attractiveness of liquid storage compared with compressed gas or hydride storage. 1 This assumes an annual operating factor of 0.9 for the electrolysis and liquefaction units. PAGENO="1215" >- ~-`~ 8 cc = c_ = cC L) V) ~ v ~ C~) b~ >< w ~- w w~ 4 L) ~ >- = v) CD - Ui ~J v) -~ cc Ui CD C,) 10 - 1209 OFF-PEAK POWER COST, mu ls/kW-h 10 C I I 0 1 2 3 4 5 PLANT CAPACITY FACTOR (See Text) FIGURE 2.4: Selling Price of Gaseous Hydrogen Required to Make the Electrolytic Hydrogen Option Competitive With Pumped Hydro Storage. PAGENO="1216" 1210 OFF-PEAK POWER COST, mill s/kW-h 10 10 - >- I- - 8- < ~. o~ < = (_) &, ~- v~ 6- ui ~ L) ~ >< 4~ Ui 5 ~ Ui (!~ 4- Ui ~ ~ ~- = ~- 2- -J Ui ~J (I, 0 0 1 2 3 4 5 PLANT CAPACITY FACTOR (See Text) FIGURE 2.5 : Selling Price of Liquid Hydrogen Required to Make the Electrolytic Hydrogen Option Competitive With Pumped Hydro Storage. PAGENO="1217" 1211 2.4.2 Intermediate Units Table 2.9 gives intermediate power production costs for the various alternatives; component costs are listed in tables 2.10 through 2.12. For intermediate duty, power pro- duction costs must be around 17 to 20 mills/kW-h to compete with pumped storage. Operating intermediate units at 4000 instead of 1000 hours per year reduces fixed charges 75%. This is the primary reason for the intermediate power costs being lower than peaking costs. To make batteries competitive for intermediate duty the capital cost would have to be less than 10 $/kW-h which is probably unrealistic. Because the batteries would have an eight hour charging time and 16 hour discharging time they would be more expensive than batteries used for peaking duty and would be less efficient [29]. As in the case for peaking, SMES capital cost would have to be less than 20 $/kW-h before they would become competitive for intermediate loading. Of the power generating alternatives the methanol fueled combined cycle system is the most attractive. Compared to the gas turbine, the increased capital cost of the combined cycle unit is more than offset by the lower fuel and 0 & M costs. The fuel would have to be an unrealistic 30C/MBTU before gas turbines would be competitive with combined cycle units. Fuel cells in intermediate duty are less attractive for two reasons: 1) their high capital cost and 2) their short lifetime (4 years at 4000 hours per year). Lowering capital costs to 140 $/kW drops power costs by 13 mills/kW-h. Doubling the operating life lowers power costs by 9 mills/kW-h. As in the case of peaking, liquid storage is the most attractive. However, in the electrolytic hydrogen options only above-ground storage is absolutely out of contention. Compared to the peaking case, the option of selling excess electrolytic hydrogen is much less attractive. The small amount of excess hydrogen produced per kW-h is the reason. Also, from a realistic standpoint there probably will never be enough off-peak power to operate electrolysis units sized at capacity factors much greater than one. 2.5 CONCLUSIONS 2.5.1 Peaking Duty Although the timing is unknown, at some future period the utilities will have to rely an fuels free coal to produce peak power. It is impossible to consider every possible option but based on this work, the most attractive future means of producing peak power is to use methanol made from coal and gas turbines or possibly fuel cells. The next most promising alternative is probably lithium or sodium-sulfur batteries, providing their capital cost is around 20 $/kW-h. However, conventional lead-acid batteries are not feasible because of price and lead availability; if all of the lead mined in the U.S. during 1971 went into batteries, they would replace only 15% of the 1973 peaking capacity, It is hard to tell which of the remaining alternatives are the most economically feasible. Before any of them can produce peaking power for 40 to 50 mills/kW-h, capital costs will have to be reduced significantly. 62-332 0 - 76 - 77 PAGENO="1218" 1212 Table 2.9 Base Case Intermediate Power Costs, tnills/kW-h Capacity 400 MW Operating Time 4000 h/yr Cost of Off-Peak Power 5 mill/kW-h Fuel Storage Gas Fuel Combined Turbines Cells cycle Hydrogen(el) Liquid 65.1 60.9 48.6 Comp. Gas A.G. 8900 4700 5400 TJ.G. 64.9 61.1 51.1 Hydride 67.2 63.6 51.6 Hydrogen Liquid 51.1 53.7 40.0 (9 l.25$/HBTU) Comp. Gas A.G. 29600 15700 18000 U.G. 111.1 88.5 83.7 Hydride 99.7 81.8 73.8 SNG Liquid 36.2 48.9 29.7 (9 l.25$/MBTTJ) Comp. Gas A.G. 8800 6000 6200 U.G. 55.2 60.4 42.6 Methanol Liquid 26.1 41.3 21.9 (9 1.25$/MBTU) Energy Storage Systems (6400 MW-h Capacity) Pumped Hydro 17.0 Batteries 69.6 SMES 104.9 PAGENO="1219" Table 2.lOa. Component Intermediate Power Costs for Hydrogen Fueled Systems using Liquid or Hydride Storage Component Capital Cost, K$ Operating Costs, nills/kW-h Fixed Charges 0 & H Fuel/Elec. CT PC CCa CT PC CC CT PC CC CT PC CC Power Cenerator 54000 134000 80000 5.4 27.2 8.0 3.4 1.5 2.1 Electrolysis Plant 56600 35600 41700 7.3 3.4 4.0 2.4 1.3 1.6 22.4 12.6 15.3 Fuel Cost 18.0 10.1 12.3 (@ 1.25 MBTU) Cryogenic Storage Liquefier 182700 114900 134600 18.2 11.5 13.4 0.5 0.4 0.4 5.3 3.0 3.6 Storage Tank 3 days storage 890 610 700 0.1 0.1 0.1 0.0 0.0 0.0 10 days storage 1950 1340 1520 0.2 0.1 0.1 0.0 0.0 0.0 Hydride Storage 3 days storage 248700 144500 173900 24.0 14.0 16.8 3.0 3.0 3.0 1.0 0.6 0.7 10 days storage 711800 407400 493000 68.8 39.4 47.7 3.0 3.0 3.0 1.0 0.6 0.7 a CC = combined cycle PAGENO="1220" Table 2.1Gb. Component Intermediate Power Costs for Hydrogen Fueled Systems using Compressed Gas Storage Component Capital Cost, K$ Operating Costs, mills/kId-h Fixed Charges 0 6 M Fuel/Elec. CT FC CC GT FC CC GT FC CC CT FC CC Main Power Generator 42900 101200 67900 4.3 23.7 6.8 2.7 1.3 1.8 14.3 8.8 10.5 Electrolysis Plant 47100 31900 36600 4.6 3.1 3.5 1.9 1.2 1.4 17.8 11.0 13.0 Fuel Cost 14.3 8.8 10.5 (0 1.25 MBTU) Compressor-Turbine 52200 35200 40500 5.2 3.5 4.0 1.6 1.1 1.3 2.9 1.8 2.1 Storage Above Ground 3 days storage 8.6xl0~1$ 4.6xl01 $ 5.2xl011$ 8340 4400 5100 540 280 330 10 days storage 2.9xl01 $ l.SxlO ~$ l.7xlO $ 27800 14700 16900 1800 950 1090 Underground 3 days storage 233000 140000 166800 22.6 13.6 16.1 1.5 0.9 1.0 10 days storage 778000 468700 556000 75.2 45.3 53.8 4.9 2.9 3.5 a. All costs, except where noted, are for underground storage. PAGENO="1221" Table 2.lla. Component Intermediate Power Costs for SNC & Methanol Fueled Systens Using Liquid Storage Component Capital Cost, K$ Operating Costs, mills/kId-h Fixed Charges 0 & M Fuel/Elec. CT FC CC CT FC CC CT PC CC CT PC CC Power Cenerator 54000 14400 80000 5.4 28.4 8.0 3.4 1.5 2.1 SEC Fuel Cost (@ 1.25 $/MBTU) 16.9 11.1 11.6 C.yg Cryogenic Storage Liquefier 55600 44000 45000 5.4 4.3 4.3 1.7 1.4 1.4 3.1 2.0 2.1 Storage Tank 2100 1400 1500 0.2 0.1 0.2 0.0 0.0 0.0 Methanol Fuel Cost (9 1.25 $/MBTU) Storage Tank 1200 900 900 0.1 0.1 0.1 0.0 0.0 0.0 PAGENO="1222" Table 2.llb. Component Intermediate Power Coats for SEC Fueled Systems Using Compressed Gas Storage Component Capital Cost, K$ Operating Costs, mills/kW-h Fixed Charges 0 6 M Fuel/Elec. CT FC CC CT FC CC CT FC CC CT FC CC Main Power Generator 50000 144000 75900 5.0 27.0 7.6 3.2 1.4 2.0 Fuel Cost 15.7 10.6 11.0 (@1.25 $/MBTU) Compressor Turbine 22000 16100 16500 2.2 1.6 1.6 0.7 0.5 0.5 1.0 0.7 0.7 Storage 10 10 10 Above Ground 8.5x108 $ 5.8x10 $ 6.0x108 $ 8200 5600 5800 530 360 370 Underground 2.7x10 $ l.8x108$ l.9x10 $ 25.8 17.4 18.0 1.7 1.1 1.2 Table 2.12 Component Power Costs for Intermediate Energy Storage Systems Component Capital Cost, g~ Operating Costs, sills/kid-h Fixed Charges 0 6 M 81cc. Pumped Storage 80000 7.5 2.0 7.5 Batteries 338000 61.5 1.0 7.1 SMES 978000 97.6 2.0 5.3 PAGENO="1223" 1217 2.5.2 Intermediate Duty Of the options considered here for intermediate duty the methanol fueled combined cycle option is the most attractive. However, these alternatives will have to compete with coal fired power plants using stack gas clean-up and/or power plants fired by low BTU gas. The low BTU gas concept is attractive because it can use combined cycle systems whereas coal fired plants cannot. 2.5.3 Base Load Duty Base load plants were omitted in this study because we were interested in energy storage concepts. However, at least two studies have considered hydrogen as a fuel for base load plants. Byron [30] considered hydrogen-air fuel cells as one of the possible advanced power generation systems. He concludes that this option could be competitive if pipeline hydrogen from coal costs around 1.25 $/MBTU and if fuel cell efficiency increases to roughly 70%. Seikel et al. [31] evaluate hydrogen-oxygen combustion powered steam-MHD power plants. Their source of hydrogen is coal and they use an on-site liquid air plant to obtain oxygen. Based on their results, the hydrogen-oxygen MHD cycle is a competitive means of producing base load power. Also, since the system is essentially pollution free, the plant could be located close to load centers. 2.6 HYDROGEN IN POWER GENERATION Based on current and anticipated technology, the near-term use of hydrogen as a utility fuel appears unlikely. High capital cost for hydrogen systems is the major draw- back. Even so, it is important to keep an open mind toward all the options; future techno- logical advances and/or governmental regulations could alter the economic assessments and results presented here. For example, advances in thermochemical decomposition of water could keep hydrogen prices down compared to fuels from coal. Also advances in liquefaction technology and schemes to recover liquefaction energy could make it more competitive. (Chapter 1 discusses these topics). If antipollution factors become more important then hydrogen or hydrogen-oxygen systems will be more attractive. The results that are presented hare are based an e~rrent and near-tern technelegy. As current technology improves or advanced technology develops these results will have to be reevaluated. The format used here allows rapid evaluation of the effect of technological progress on power production costs. 2,7 ACENOWLEDGMENT The author thanks Messrs. R. V. Hugo and W. S. Landers of the Public Service Company of Colorado for their many helpful suggestions. PAGENO="1224" 1218 2.8 REFERENCES [1] Federal Power Commission, 1970 National Power Survey, Part IV p iv-4-22. [2] Lewis, P. A., and Zemboski, .2., Energy Storage in Future Electric Power Systems, paper presented at the 1973 IEEE INTERCON. [3] Dupree, W. G., and West, J. A., United States Energy Through the Year 2000, U.S. Department of the Interior (Dec. 1972). [4] Ashworth, R. A., and Bolez, C. A., A Dollar and Cents Approach to the Clean Conversion of Coal to Electric Power, Paper No. 7d, AIChE 74th National Meeting, New Orleans (March 1973). [5] Kyle, N. L., Cairns, E. .2., and Webster, B. S., Lithium/Sulfur Batteries for 0ff-Peak Energy Storage: A Preliminary Comparison of Energy Storage and Peak Power Generation Systems, Argonne National Laboratory Report No. ANL-7958 (March 1973). [6] Szego, G. C., The U.S. Energy Problem, Vol II. Report No. C645 prepared for NSF-KAHN (Nov. 1971). [7] Post, R. F., and Post, S. F., Flywheels. Sci. Amer. 229. (6) 17 (Dec. 1973). [8] Korsmeyer, K. B., Underground Air Storage and Electrical Energy Production, Oak Ridge National Laboratory Kept. No. ORNL-NSF-EP-ll (Feb. 1972). [9] Hugo, K. V., Public Service Company of Colorado, Denver, Colorado, private communication (1973). [10] Balet, W. .2., Federal Power Commission, Washington, D.C., private communication (1973). [11] Lueckel, W. J., Eklund, L. G., and Law, S. H., Fuel Cells for Dispersed Power Generation, IEEE Trans. PAS-92 (1) 230 (1973). [121 Federal Power Commission, National Power Survey, Energy Distribution Research, (to be published). [13] Boom, K. W., McIntosh, G. E., Peterson, H. A., and Young, W. C., Superconducting Energy Storage, Book, Advances in Cryogenic Engineering 19, (Ed.) K. D. Timmerhaus, pp. 117 (Plenum Press, Inc., New York, N.Y., 1974). [14] Wentorf, R. H., Jr., and Hanneman, R. E., Thermochemical Systems for Hydrogen Generation, Paper No. 3, Fuel Chemistry Division, 166th ACS Meeting, Chicago (August 1973). [15] Marchetti, C., Hydrogen and Energy, Chem. Econ. Eng. Rev. 5, (1) 7 (Jan. 1973). [16] Katell, S., U.S. Bureau of Mines, Morgantown, West Virginia, private communica tion (1973). [17] Kincaide, W. C., and Williams, C. F., Storage of Electrical Energy Through Electrolysis, paper presented at the 8th IECEC, Philadelphia (August 1973). [18] Hallett, N. C., Study, Cost, and System Analysis of Liquid Hydrogen Production, NASA Report No. CR 73, 226 (June 1968). PAGENO="1225" 1219 [191 Guthrie, K. M., Data and Techniques for Preliminary Capital Cost Estimating, Chem. Eng. 114 (March 24, 1969). [20] Gregory, D. P., A Hydrogen-Energy System, Amer. Gas~ Assoc. Catalogue No. L21l73 (August 1972). [21] Islet, K. J., Brookhaven National Laboratory, Long Island, New York, private communication (1973). [22] Reilly, J. J., and Wiswall, Jr., R. H., Iron Titanium Hydride: Its Formation, Properties, and Application, Paper No. 5, Fuel Chemistry Division, 166th ACS Meeting, Chicago (August 1973). [23] Siegel, H. N., and Kalina, T., Technology and Cost of Coal Gasification, Mech. Eng. 95, (5) 23 (May 1973). [24] Wenzel, L. A., LNG Peakshaving Plants - A Comparison of Cycles, Paper No. C-l, Cryogenic Engineering Conference, Atlanta (August 1973). [25] Schmidt, A. F., Cryogenics Division, National Bureau of Standards, Boulder, Colorado, private communication (1973). [26] Garrett, D., and Wentworth, T. 0., Methyl-Fuel - A New Clean Source of Energy, Paper No. 9, Fuel Chemistry Division, 166th ACS Meeting, Chicago (August 1973). [27] Hassenzahl, W. V., Baker, B. L., and Keller, N. E., The Economics of Supercon- ducting Magnetic Energy Storage Systems for Load Leveling, A Comparison with Other Systems, Los Alamos Scientific Laboratory Informal Report No. LA-5377-MS (August 1973). [28] Rielly, J. J., Brookhaven National Laboratory, Long Island, New York, private communication (1973). [29] Kyle, M. L., Argonne National Laboratory, Argonne, tll. private communication (1974). [30] Baron, S., Cost-Benefit Analyses of Advanced Power Generation Methods, Proc. American Power Conference, 35, 451 (1973). [31] Seikel, G. R., Smith, J. M., and Nichols, L. 0., H2-02 Combustion Powered Steam-MHD Central Power Systems, paper presented at THEME Conference, Miami Beach (March, 1974). PAGENO="1226" 1220 2.9 APPENDIX A Sample Calculation of Power Production Cost The most difficult part of any economic analysis is obtaining reasonable cost figures; the calculations from that point on are usually straight forward. That is the case here; however, a sample calculation is in order because it clearly shows how we arrived at power production coats. For this example we choose a fuel cell using electrolytic hydrogen to produce 100 MW of peaking power and then make detailed calculations for the power generator and electrolysis plant. The peaking unit will operate 1000 h/year and the fuel cell life is taken as 16000 h, inverter life is 20 years and electrolyzer life is 25 years. 2.9.1 Power Generating Unit Capital Cost: From Table 2.2 we obtain a capital cost of 290 $/kW for the fuel cell and 45 $/kW for the DC-AC inverter (no reformer is needed since we are using hydrogen as the fuel). The total capital cost of the unit is $335 x l0~. Fixed C~gq~: The fixed charge rate must be figured separately for the fuel cell and inverter because they have different plant lives. For the fuel cell we first need the capital recovery factor (CRF) which is n CRF = FCR(1+FCR) (A-l) (1 + FCR)~ - 1 where FCR is the fixed charge rate (15%/yr) and n is the plant life (16 years in this example). For the fuel cells CRF is 16.8%/yr and for the inverter it is 16.0%/yr. Multi- plying the capital cost times CRF gives the size of the annual payment required to regain the initial capital investment after n years if the interest rate is the fixed charge rate. Fixed charges in terms of power production are FC(mills/kW-h) = xT (A-2) where TCC is the total capital cost, P is the power and T is the annual operating time. Then for the fuel cell and inverter FC = 2.9 x 1O7 x 0.l68+4.5xlQ ~ - ~ mills/kW-h. ~pg~nandMaintenance~!~. 0&M costs for the fuel cell are estimated to be 3.4 mills/kW-h. 0&M for the inverter is assumed to be zero in this study. Fuel and Power Cost: Since we are using electrolytic hydrogen there is no power or fuel charge here; however, we still need to calculate how much hydrogen is required for the plant. To produce one kh'~he using a fuel cell with 50% efficiency we need lb H 51,570 BTU(LHV) x x = 0.132 lb H2/kW-h. The flowrate is 0.132 x l0~ lb/hr and the maximum consumption in one day is 1.32 x l0~ lbs. PAGENO="1227" 1221 2.9.2 Electrolysis Unit Capital Cost: From the above calculation we know the hydrogen consumption per day (1.32 x l0~ lb). To size the plant we divide this number by eight (we assume an eight hour operating day) and multiply the result by 0.75 since the plant is sized at 75% of the maximum daily load. Thus we obtain 12375 lb/hr for plant capacity. From Table 2.3 the capital cost is $930 x l0~ (12375/833)0.8 or $8.07 x 106. Fixed Charges: Using 25 years as the plant life for the electrolysis unit we obtain a capital recovery factor of 15.5%/yr. From Eq (A-2) we obtain fixed charges of 12.5 mills/kW-h. Operating and Maintenance Cost: In this case O&M costs are taken as 0.01 $/lb of hydrogen produced. Since the fuel cell requires 0.132 lb H2/kW-h, O&M costs are 1.3 mills/kW-h. Fuel and Power Costs: No fuel is needed but a large amount of electrical energy is needed (19 kW-h/lb). Assuming power costs 5 mills/kW-h the cost of power per unit of energy output is 5 mills/kId-h x 19 kId-h/lb H2 x 0.123 lb H2/kW-h = 12.55 mills/kId-h. All of the other calculations can be made in a manner similar to the ones presented here. 2.10 APPENDIX B: Hydride Storage Cost Data As mentioned in the text, hydride storage is still in the developmental stage; there- fore any cost estimates must be considered preliminary. Complete cost details for hydride storage were omitted in the text because the cost is a function of the charging and dis- charging flow rates, and the total amount of hydrogen stored. All numbers are based on cost estimates by R. J. Isler [21]. 2.10.1 Cost Components Dependent Upon Amount of H2 Stored Hydride (FeTi): 38.75 lbFeTi ~ = 38.75 lb H2 stored Hydride Storage Vessel: 154.7 (lb H2 stored)°8 = $ (inc1~des fdlters) Dissociation Energy: 1960 BTU/lb H2 (taken at no charge in these calculations). 2.10.2 Cost Components Dependent Upon Discharge Flow Rate Heat Exchanger: 1892 (lb H2/hr)0~65 = $ Recirculation Compressor: 993 (lb H2/hr)°8 - $ 2.10.3 Cost Components Dependent Upon Charging Flow Rate Charging Compressor: 2233 (lb H2/hr)°8 = $ Heat exchanger: 301 (lb H2/hr)°~65 - PAGENO="1228" 1222 CHAPTER 3 H2 FUELED AUTOMOBILES R. 0. Voth 3.0 SUMMARY There are no insurmountable technical problems that must be solved before hydrogen can be adopted as a synthetic fuel for use in transportation. Internal conbustion engines, external combustion engines, and fuel cells either work best with hydrogen or are easily adapted to hydrogen fuel. The use of hydrogen in conventional or advanced engines tends to increase their efficiency while reducing polluting emissions. The cost of hydrogen and the cost of hydrogen storage onboard a vehicle are major economic barriers to the adoption of hydrogen fuel. Compressed gas storage is bulky and heavy and requires additional energy to compress the gas. The onboard storage of cryogenic liquid involves an expensive storage dewar, additional expense to liquefy gaseous hydrogen, and the venting of boiloff gases which, besides being a safety problem, adds to the operating cost of the vehicle. The onboard storage of hydrogen in a metal hydride is an economic unknown. The heavy weight of the hydride increases the energy consumed by a vehicle, thereby increasing the cost of operation, and the hydride requires a heat of dissociation which may or may not be available as reject heat from the onboard engine or fuel cell. The following is a review of work being conducted on transportation power sources using hydrogen fuel and on methods of storing hydrogen on a vehicle. An economic comparison of the cost of operating a small intensively driven car for intercity use with various fuels, engines, and fuel storage methods is also presented. 3.1 INTRODUCTION Currently, transportation consumes approximately 25 percent of the energy consumed in the U.S. Projections [11 indicate that transportation will continue to consume this portion although the portion used by the automobiles will decrease from the current 85 percent of the transportation total to 65 percent by the year 1990. The transportation industry is a major user of petroleum. It is now consuming approximately 55 percent of the oil used in the United States, and projections indicate this fraction will increase to 60 percent by the mid-eighties. The need to import petroleum products to meet this demand has caused many authorities to suggest the adoption of a synthetic fuel to be used for transportation. With a suitable primary energy source, hydrogen could serve this purpose. The choice of synthetic fuel to be used by transportation is determined not only by economics but also by social and therefore political pressures to reduce polluting emissions. Because of the emission problem a purely objective decision on the type of synthetic fuel to be adopted by transportation is not possible. The choice of hydrogen as a synthetic fuel is based on reduced emissions, adaptability of hydrogen fuel to current transportation power sources, and the ease of storing and dis- tributing energy in the form of hydrogen; also, hydrogen offers a short-cycle ecological fuel, i.e., water-to-hydrogen-to-water. This chapter is primarily concerned with the adaptability of hydrogen as an energy source for transportation. PAGENO="1229" 1223 The following sections review the research work currently being conducted on heat engines and fuel cells. Also, a simplified analysis of the economics involved in the use of hydrogen fuel in an intercity automobile is presented. 3.2 SAFETY OF HYDROGEN FUEL Before hydrogen can be adopted as a synthetic fuel for general use in vehicles, its ignition and flammability characteristics should be considered. These properties are used to design a hydrogen engine and to determine safety precautions involved in handling the fuel. Although liquid hydrogen involves cold temperatures (20.27 K) resulting in the freezing of human tissue exposed to the liquid, the properties of hydrogen of most concern are the gaseous ignition temperature and ignition energy, detonability limits, and f lam- mability limits. Table 3.1 gives a comparison of the ignition and flammability characteris- tics of hydrogen with other fuels in air. Hydrogen in air displays a relatively high igni- tion temperature and a wide flammability range. Table 3.1 Ignition and Flammability Properties Auto Ignition Limits of Stoichiometric Temperature Flammability [2] Mixture [3] [2] Volume Percent Volume Percent of fuel in air of fuel in air Lower Upper Hydrogen 585[4] 4.0 75 29.6 Gasoline 440 1.3 7.1 1.3 Diesel fuel 225 -1.2 Methane 540 5.0 15.0 9.5 Methanol 385 6.7 36 12.3 Table 3.1 indicates that the flammability range for hydrogen is much wider than for gasoline but gasoline has a lower flammable limit. Thus, gasoline will burn at lower fuel-in-air concentrations but as the concentration increases hydrogen remains an explosive threat and gasoline becomes non-flammable. Based on the lower flammable limit hydrogen appears safer than gasoline. Based on the flammable range hydrogen appears more hazardous than gasoline. The time required to reach the lower flammable limit favors gasoline be- cause hydrogen is much more volatile and/or stored at higher pressure; however, flammable hydrogen concentrations will also dissipate much more rapidly than gasoline-in-air as a result of buoyant forces. The wide flammability range makes even small leaks from a hydrogen fuel system into an enclosed area a safety problem. Assuming a 6.1 m (20 ft) x 6.1 a x 2.4 a (8 ft) garage enclosure, a leakage rate of .15 m3/h or .00251 m3/min would provide sufficient hydrogen in 24 hours to yield a flammable mixture in the garage. The garage would need to be free of leaks itself in order to contain the hydrogen for this period of time because of the rapid dispersion characteristics of hydrogen (high diffusion and buoyant leakage flows). Nonetheless, a hydrogen fuel system free of leaks is mandatory. PAGENO="1230" 1224 A more serious circumstance for a contained leak exists if the leak is of sufficient size to provide a detonable mixture within the enclosure. The detonability limits for hydrogen are 18-59 percent hydrogen by volume in air [5]. In the above enclosure a con- tained leakage rate of 0.679 n3/h or 0.011 m3/min would provide sufficient hydrogen to reach the lower detonability limit in 24 hours. Experiments with gaseous hydrogen-air mixtures have shown that a detonable mixture ignited by a strong detonation source or ignited while it is enclosed on three sides, may detonate resulting in severe explosive damage. Again, the high dispersion rate of hydrogen would tend to reduce the possibility of reaching a mixture of these proportions in the 24-hour period. The high auto-ignition temperature of hydrogen-air mixtures would indicate that the mixture is difficult to ignite; however, the energy required to ignite hydrogen-air mix- tures is an order of magnitude lower than that required by gasoline-air mixtures. A hydrogen fire can be initiated by an electrostatic discharge from a person even though the discharge is of such low intensity that the person would not feel the discharge. The radiation from a hydrogen-air fire is 1 to 10 percent of that from a comparable hydrocarbon fire because of the low emissivity of the hydrogen flame. Besides the low esissivi ty, the radiation from a hydrogen fire is at avows lemgth that is readily absorbed by the atmosphere; the radiation intensity therefore decreases rapidly with distance from a hydrogen fire. Also, smoke inhalation is a serious health hazard in hydrocarbon fires and non-existent in hydrogen fires. Based on the flammability and explosive characteristics of hydrogen, any hydrogen system must be designed with great care if it is to be placed into the hands of the general public. Leakages of hydrogen must be virtually eliminated, and uncontrolled venting cannot be tolerated. 3.3 POWER GENERATING DEVICES FOR USE WITH HYDROGEN In order to use hydrogen as a fuel for transportation, heat engines must be adapted to the fuel characteristics. The wide flammability limit, which was a detriment to safe handling, helps when hydrogen fuel is used in an internal (IC.) or external combustion engine. Because of the wide flammability range of hydrogen, it is possible to run the hydrogen fueled IC. engines fuel lean. Running the engine with excess air lowers the combustion temperature which in turn reduces the NO emission from the engine. Although the high auto ignition temperature of hydrogen-air mixtures would again indicate the mixture would be hard to ignite, the opposite is true. Fluffy deposits of carbon or other particles in the combustion chamber causes I.C. engines to backfire under certain condi- tions, probably because the hot deposits ignite the fuel mixture before the intake valve closes. The low energy required to ignite the hydrogen air mixture is the cause of the backfiring phenomenon. The tendency to backfire can be reduced by cleaning the combus- tion chamber, by using special cool-running exhaust valves and spark plugs, by running with fuel-lean mixtures, and carefully routing ignition wiring [32] or using a special distributor cap to ground spark plugs except when they are fired. Since hydrogen fuel burns thoroughly, and since no hydrocarbons are involved in the combustion process, the exhaust constituents are water from the combustion process, oxides of nitrogen, and other atmospheric components. Griffith [36] has pointed out that PAGENO="1231" 1225 exhaust emissions from hydrogen-fueled engines may contain low concentrations of hydrogen peroxide. Also, low concentrations of ammonia and hydrazine may possibly be produced in such engines. Although hydrogen-fueled engine exhausts have not been carefully analyzed for these contaminants, they are not considered [34] a significant threat to the use of hydrogen fuel. 3.3.1 The Internal Combustion Engine Using Hydrogen Fuel A comprehensive history of the use of hydrogen to fuel internal combustion engines is presented by Billings and Lynch [6] and Weil [7]. Hydrogen, mainly from town gas rich in hydrogen, was used with IC. engines as early as the 19th century. Even as early as 1923, the ability of hydrogen to run in an IC. engine with a fuel lean mixture was recognized. High indicated thermal efficiencies were achieved with the fuel-lean mixtures. The engines used with the Zeppelin airships were converted to run on a partial charge of hydrogen in order to conserve the primary hydrocarbon fuel carried on board. Both spark ignition and compression ignition engines were partially fueled with hydrogen. The Great Britain Royal Airship Works also experimented with hydrogen fuel in their airships with equal success. Because hydrogen is such an ideal fuel, two engines [8] are currently being developed that use a reaction chamber to convert a hydrocarbon fuel, water, and air to a mixture of hydrogen, carbon monoxide, and carbon dioxide. In one of the engines this gaseous mixture is inducted into the normal air and hydrocarbon mixture to improve combustion. The other engine runs on the mixture of reformed gases and air only. Both systems require water that is used in the reforming process, but the engines have demonstrated reduced emissions and slightly increased thermal efficiencies. The water can be obtained from onboard storage or condensed from the engine exhaust. Different investigators have taken different approaches to the pure hydrogen-fueled internal combustion engine. The simplest conversion is to induct hydrogen into the intake air. By maintaining a fuel-lean mixture and varying the charge with an intake throttle valve, the thermal efficiency of the engine can be maintained at a high value while main- taining low NOx emissions and a low probability of backfiring. The major problem with this approach is that the engine power per unit of displacement is reduced nearly 50 percent compared with a similar engine using gasoline. The compression ratio of the engine can be increased somewhat while maintaining the fuel-lean mixture to recover some of the power capability of the engine and to further increase its efficiency. Another approach to the hydrogen IC. engine is to inject water with the hydrogen to lower the combustion temperatures. With this approach the NO emissions can be maintained at a low value at richer fuel-air mixtures. With water injection, the output of the engine approaches 75 percent of a similar displacement gasoline engine without significant NOx emissions or backfiring [9]. Exhaust recirculation is another approach to allow a richer fuel-air mixture without backfiring while maintaining low NOx emissions. Again, the power per unit displacement is reduced below that of a gasoline engine by approximately 40 percent. PAGENO="1232" 1226 A combination of these methods would use lean fuel mixtures at part load on the engine to increase the efficiency of the engine and reduce the NOx emission, while at peak loads the fuel-to-air mixture could be made richer with the addition of water or the use of exhaust gas recirculation in order to maximize output with low NOx emissions. Two other noteworthy experimental engines used a more direct method of injecting the hydrogen into the engine. The first used a modified single cylinder, small gasoline engine with the hydrogen injected directly into the combustion chamber [10]. The modifications of the engine included a mechanism to control a fuel injector valve and a boiling water cooling system to replace the normal air cooling. The fuel injection start time, the spark time, and the injection stop time could be adjusted in the experimental engine. Fuel flow to the engine could also be adjusted by varying the fuel supply pressure. Fuel supply pressure was as high as 66 atmospheres in some high-power output tests. Although fuel consumption of the engine was slightly higher than expected because of the additional valve-activating mechanism for the fuel injector and an incorrectly shaped combustion chamber, the NO emissions were a small fraction of the emissions obtained from gasoline tests. Another engine tested with hydrogen fuel [11, 12] used a specially designed intake valve. When the intake valve opened, unthrottled air was inducted along with hydrogen from a special port installed in the intake valve seat. The engine power was changed by changing the amount of fuel inducted by varying the fuel supply pressure. At low power output, the combustible mixture was very fuel lean, and as power increased, the fuel mix- ture approached more nearly the stoichiometric mixture. Since the intake air is not throttled, the pumping losses are decreased and the part load efficiency of the hydrogen fueled l.C. engine behaves more like the higher part load efficiency of a Diesel cycle engine. The NO emissions from this engine were low at part loads, but at full load, exhaust gas recirculation or water injection would be necessary to reduce the NO emissions to an acceptable level. A Diesel cycle engine to use hydrogen fuel has been proposed [13]. The Diesel cycle is distinguished by a constant pressure combustion process because the fuel is injected and burned during part of the power stroke of the piston. Ignition in a Diesel cycle is usually obtained by having high temperature air, obtained by compression, in the combustion chamber. Because of the high ignition temperature of hydrogen, a compression ratio of at least 35:1 is required for an ideal specific heat ratio for air of 1.4 to obtain the hydrogen auto ignition temperature. Since heat is transferred to the cylinder walls during compression, a more realistic compression ratio of 83:1 (n = 1.35) is required in order to obtain the de- sired compression ignition. Since these high compression ratios are not possible, the hydrogen Diesel cycle engine would require an auxiliary ignition source. An electric glow plug or other hot spot in the cylinder could provide the required ignition source. However, unless this ignition source were located to ignite the very first portion of the fuel injected, the cycle on a pressure-volume diagram would probably more closely resemble an Otto-cycle than a Diesel cycle. PAGENO="1233" 1227 3.3.2 External Combustion Engines For external combustion engines such as the Stirling cycle engine, Rankine cycle engine, or gas turbine engine the only design problem different for hydrogen (from other fuels) is the design of the combustor. Because hydrogen is easy to burn, the burner design is relatively simple. Designing for minimum NO, a more difficult design, requires a uniform flame temperature without local hot spots [14]. Because hydrogen will burn readily with an excess of air, the NOx emissions from a combustor using hydrogen should be less than can be obtained from a fossil fueled combustor. Since the combustion process is more readily controlled in a combustor than in an I.C. engine, considerable development of efficient burners is currently proceeding for the hydrocarbon fuels. Using hydrocarbon fuels, the NOx emissions can be reduced to an equivalent of 0.18 g/mile with a Stirling cycle engine compared with the 1975/1976 requirements of 0.4 g/mile [15]. Using a hydrogen fuel combustor, the NO emissions will be at least as low as can be obtained with fossil x fuels. Gas turbines have been converted to hydrogen fuel. The first gas turbine to use hydrogen gas was a fossil fueled engine converted to hydrogen in 1956 [161. The only major change required on the existing engine was an external heat exchanger to convert liquid hydrogen (the fuel used) to a gas before it was injected into the burners. Because of the excellent mixing and combustion properties of hydrogen, acceptable combustion efficiencies could be obtained with hydrogen in about one-quarter the combustor length required for hydrocarbon fuels. The turbine eould operate with a combustion chamber temperature of less than 200cF, and under this condition the turbine turned so slowly that the first stage compressor blades could be counted. After the successful conversion, a gas turbine designed specifically for hydrogen was also built and tested. No problems with this turbine are reported although actual data are scarce because the original work was classified. Three successful flights of a twin-engine light bomber with one engine converted to hydrogen above 50,000 feet were accomplished by the NACA in 1957 [17]. No problems were encountered in the test flights. The experimental results from both internal combustion and external combustion engines indicate that no significant technological breakthrough s are required. Although unburned hydrocarbons and carbon monoxides are not a problem with hydrogen fuel, NOx is still a partial problem in air-breathing engines, but can be minimized by design modification. Combustion of hydrogen with oxygen eliminates the NOx problem. 3.3.3 Fuel Cells Fuel cells were conceived by Sir William Grove in 1839, but because the dynamo was coming into being around 1890, no serious battery development was accomplished until about 1944. At that time fuel cells came under active development because of the emerging space program and because fuel cells could theoretically yield a high conversion efficiency. Current development involves fuel cells for the power utilities, fuel cells for long life remote applications, fuel cell electrode development using less expensive materials, and fuel cells for space applications. Although significant amounts of development money have been spent on fuel cells, fuel cells are not generally available except as custom designs, and they are not generally used except in systems where the use of any other power source is impossible. 62-332 0 - 76 - 78 PAGENO="1234" 1228 The basic fuel required for current fuel cells is hydrogen. In some of the applica- tions being considered for fuel cells, hydrogen is provided by reforming heavier hydro- carbons. A specific example of this type of application is the current development of a fuel cell to be used as a peak power source for the electrical utilities [18]. The conversion efficiency of the fuel cell is one of its major advantages. At full capacity the conversion efficiency of a hydrogen-air fuel cell is slightly higher than that of a fully loaded heat engine. As the load decreases, the efficiency of the fuel cell in- creases while the efficiency of heat engines decreases. As a result the fuel cell will display significantly better efficiencies than heat engines in applications where the mean load is less than the full capacity of the power source. An economic analysis [19] of the fuel cell versus other heat engines is available with a definition of the economic size of the fuel cell versus capital costs and fuel costs to achieve the lowest overall operating cost. Data concerning emissions from a fuel cell using a reformed hydrocarbon fuel are presented by Lueckel [18]. Table 3.2 is a sample of these data converted to g/mile assuming an average power consumption for a vehicle of 1 kW-h/mile [20]. Many of the emissions result from the dirty gas that was used as the fuel. If pure hydrogen were used as the fuel, the only emission would probably be the low NO pollutant. The major disadvantages of the fuel cell are its high cost, heavy weight, and large volume. The high costs are a result of the one-of-a-kind production method of custom designs. Also current hydrogen-air fuel cells employ a platinum catalyst costing approxi- mately $50/kW [21]. Table 3.2 Probable emission characteristics of a fuel cell powered vehicle using a reformed hydrocarbon fuel - 1976 Clean Air Act Vehicle Emissions Requirements Unburned Hydrocarbons 0.41 g/mile 0.104 g/mile Carbon Monoxide 3.4 g/mile not given Nitrogen Oxides 0.4 g/mile 0.109 g/mile Current costs of fuel cells vary from a high of $40,000/kM for the high reliability fuel cells for space use [22] to a low projected cost for the electric utilities fuel cell of $130/kM [18]. Cost projections based on the elimination of the platinum catalyst and the use of mass production techniques are as low as $18 - $30/kM [19]. All the above costs are for the full capacity output of the units and do not reflect the purchase of a higher capacity fuel cell for increased efficiency in a particular application. Table 3.3 shows the weights and volumes of fuel cells compared with other more common power sources. The lead-acid battery has a high energy density; however, it lacks sufficient power density to be considered in most vehicle applications. The fuel cell has a relatively low energy density; however, it will supply power for as long as it re- ceives fuel. The projected data for the dissolved methanol fuel cell indicates that it will have limited application in the transportation industry because of its large size PAGENO="1235" 1229 and weight. Methanol or other petroleum fuel can be reformed to supply a hydrogen rich fuel for a hydrogen-air fuel cell; however, when the weight of the reformer is added to the weight of the fuel cell, the total weight approaches 25 - 40 kg/kW [19]. This high weight eliminates the use of a fuel cell with fuels other than hydrogen for small cars. Although fuel cells are not fully developed, the high thermal efficiencies possible from fuel cells makes their use in transportation more desirable as fuel costs rise. Since hydrogen is a natural fuel for the fuel cell, the general availability of hydrogen would also increase the desirability of using the fuel cell in transportation. Table 3.3 Range of fuel cell weights and volumes compared to other power sources Wt/Max. Power Vol./Max. Power kg/kW m3/kW Low temperature hydrogen-air fuel cell with liquid electrolyte from [21] 27.2 0.02 - 0.03 Projections from [19] 15 - 20 electrovan Oxygen-hydrogen from [23] 9.6 Low temperature hydrogen-air fuel cell with solid electrolyte from [19] 10 - 15 0.005 - 0.015 Low temperature dissolved methanol fuel cell from [19] 30 - 45 .06 - .09 IC. Engine from [3] 3 - 4.3 0.003 Lead-Acid Battery from [24] 10 - 100 0.3 3.4 FUEL STORAGE ABOARD A VEHICLE Although considerable research is being conducted on power sources for use in a vehicle, the major work being done on hydrogen fuel storage systems applicable to a vehicle is in the area of metallic hydride storage. Compressed gas storage and cryogenic liquid hydrogen storage are in widespread use and little research work is necessary in these areas except to match the storage container to the chosen power source; to perfect filling pro- cedures, and in the case of liquid storage, to develop a safe system to vent boil-off gases. A prototype liquid hydrogen dewar for use onboard a car has been manufactured [35] and a liquefied-natural-gas dewar can easily be converted [26] to liquid hydrogen use. Compressed gas storage for vehicle use is too bulky and heavy to furnish the desired range from a vehicle. Several experimental vehicles are currently being fueled with liquid hydrogen [25,33,34] and a previous experimental car used liquid hydrogen and liquid oxygen to provide fuel and oxidant for a fuel cell [23]. No particular problem was encountered with the liquid storage except for some pulsating pressure from the vaporizer on the fuel cell vehicle. In general new designs using existing technology must be developed to handle the safe venting and filling procedures for the liquid containers; however, no technological breakthroughs are necessary to store liquid hydrogen aboard a vehicle. PAGENO="1236" 1230 Costs related to liquid storage involve the cost of the onboard container or dewar, the added costs of hydrogen due to the liquefaction process, and any additional costs in- volving venting of hydrogen overboard. A car-sized dewar for liquid hydrogen currently costs about $900.00 [26], and projections of $250 [27] to $500 [25] have been made for mass produced dewars of similar size. Unless the cost of liquefying hydrogen is written off to reduce transmission or storage costs, the selling price of liquid hydrogen will be $0.17/kg higher than the basic gaseous hydrogen costs. This added cost of the liquid fuel may be reduced slightly by recovering a portion of the liquefaction energy onboard the vehicle. The boiloff rate for the onboard dewar is determined partially by the cost of the dewar; however, with current technology a 1% boiloff per day should be achievable. Assuming an average range of 400 km for a vehicle, the 1% boiloff requires the vehicle to be driven an average of 4 km per day to use the boiloff gases. However, the average car is driven 42 km per day [1] and boiloff rate should not be a problem. Hydrogen storage in a metal hydride does not have the extended history of compressed gas or liquid storage, but some general characteristics of metal hydrides have been mea- sured. These characteristics are shown in table 3.4. Because of the heavy weights or high dissociation temperatures of most of the hydrides, the NgH or MgN1H are considered the most probable for use with a vehicle. Although the theoretical properties of the metallic hydrides are known, the performance degradation of the material with repeated usage has not been determined and even in carefully controlled experiments MgH could be loaded to only 80 percent of its theoretical capacity. Dissociation heat at the 1 atm equili- brium temperature may or may not be available from the heat rejected by the vehicle power source. Two investigators, [28 and 30], have theoretically determined the balance between the heat rejected by an I.C. engine and the heat required by MgH and they found the balance sufficient. Others [37] are more skeptical of the ability to use waste engine heat to dissociate the hydrides. The theoretical results [28,30] considered the possibility of increasing the available heat from the engine exhaust by decreasing the heat rejected to the engine cooling water. Also, to return a partially depleted and cooled MgH bed to operating temperature some hydrogen must be burned. Indications are that NgH requires a significant overpressure during loading to reduce the loading time to acceptable limits. The addition of the nickel catalyst reduces the required overpressure and the degradation of the material with time but also decreases the amount of hydrogen stored [29]. Another problem with hydride storage aboard a vehicle is the safety aspects of the storage medium. As magnesium is cycled to the hydride form and back to the pure form many times the material tends to form fine grains. The granular hydride becomes highly pyrophoric. Besides the hazards associated with handling large quantities of this material, the hazards of a magnesium fire following a vehicle accident with a partially depleted bed is severe. The adoption of any hydride, but especially of a hydride involving magnesium, f or fuel storage aboard a vehicle may depend more on the hazards involved with the hydride than for other technical or economic reasons. PAGENO="1237" 1231 `Cost factors are difficult to determine for the metallic hydride storage system be- cause a working system has not been designed. In order to effectively use the reject heat from the vehicle power source, a highly efficient heat exchanger must be included in the hydride bed. Besides the expense of the heat exchanger, it may add significant volume and weight to the hydride bed. Table 3.5 shows a comparison of the various methods of hydrogen storage with the storage of an equivalent amount of energy in gasoline and methanol. The unacceptability of compressed gas storage is apparent because of its large volume, heavy weight, and high capital costs. The volume required by the liquid hydrogen and the MgH storage is nearly the same although the weight of the hydride storage is considerably higher. MgNiH storage is significantly larger and heavier than that of liquid hydrogen or MgH. Gasoline storage is the best, followed by methanol and liquid hydrogen. 3.5 ECONOMIC ANALYSIS OF THE USE OF HYDROGEN FUEL FOR A SMALL AUTOMOBILE In order to compare the possible power sources, fuels, and methods of storing the fuel, calculations were performed to determine the cost of operating a specific auto over a defined driving cycle. The type of auto selected was an intensively driven intercity vehicle because in this type of vehicle the high capital expense of a higher efficiency power plant can be amortized over a larger number of miles. Since projected fuel costs are high, a higher efficiency power plant should be best suited to an intensively driven vehicle. The performance characteristics of this auto were chosen to be near that of a small, low powered car similar to the American sub-compact or small Import car. Acceleration to 64.4 km/h (40 miles/h) was specified to be 12 seconds. The power calculated as necessary to achieve the required acceleration was sufficient for all other operating modes of the vehicle including a continuous cruising speed of 64.4 km/h. The basic car body and frame were assumed to weigh 680 kg with an additional load of 363 kg for passengers and baggage. The total weight of the car was varied in the calculations due to the varying storage weights of the fuel and corresponding engine weights. The total weight of the car ranged from 1160 to 2960 kg, depending upon the engine-fuel option selected. Weights and costing faetsrs for the defined car are shown in table 3.6. Most con- ventional materials were assumed to cost $3.3/kg, as fabricated, while increased costs were used for non-conventional materials. The capital costs were amortized over their life (given in table 3.6) assuming 15 percent interest on the capital investment. The driving cycle used to determine the required stored energy aboard the car was calculated using a time cycle of 8 hours. The car cruised at 64.4 km/h on level roadway for 60 percent of the 8 hours, accelerated to 64.4 km/h for 26.7 percent of the 8 hours, and decelerated to 0 km/h for 13.3 percent of the time. A total distance of 435 km was traveled during the driving cycle. For this driving cycle an average energy consumption of .23 kW-h/km was calculated for a vehicle weighing 1600 kg. This average energy con- sumption compares favorably with that calculated by Salihi [20] for the same weight vehicle performing according to the Federal driving cycle. No energy recovery was included during the deceleration periods. PAGENO="1238" `rable 3.4. Properties of certain metal hydrides. Initial and final composition Li LiH Mg MgH2 Ca-.-CaH2 Na-.~NaH Mg2NiH0 ~ .-...Mg2NiH4 2 I<-'-KH UH0 ~ UH2 0 FeTiH01-.-FeTiH1 0 $ 0.84 $ 4.85 4.2 525 $ 0.66 3.5 250 $ 2.20 2.5 715 $ 0.77 2.0 12 $ 8.82 $ 4.23 0.75 0.31 0.72 0.42 0.27 0.47 0.17 0.10 Dissociation Heat [28, 291 Available Equilibrium of Heat to low Heat A H , kW-h/kg of H2 wi % H~ Temperature at 1 atm ofH2('C) metal perkg of Combustion 12.7 7. 7 4. 8 - 25. 0 - 10. 3 - 24. 1 - 13.9 - 8.9 - 15.7 - 5.6 290 920 - 3.2 0.9 PAGENO="1239" Table 3. 5 Comparison of hydrogen storage methods to gasoline and methanol. Lower Heat Energy Content* Cost Value Fuel Wt Fuel Volume Including Container of Container Fuel Storage Method (kWh/kg) (kg) (m3) (kW-h/kg) (kW-h/m3) CompressedGas1 33.33 17.6 1.19 .612 447.44 $3160. Cryogenic Liquid2 33. 33 17. 6 0. ~49 10. 15 1929. 5 $250 - $900 Hydrogen 3 Mgi-I2 Hydride 33. 33 17. 6 0. 264 2. 53 2219. 7 $ 347. MgNiH2 Hydride4 33. 33 17. 6 0. 558 1. 19 1050.2 $1398. Gasoline Liquid 12. 92 45. 36 0. 0674 10. 90 8548. 8 $ 30. Methanol Liquid 6. 20 94. 5 0. 1180 5.45 4896.8 $ 42. Total energy content was 586 kW-h 1 Gas at 136 atm., 300 K 2. Saturated Liquid at 1 atm absolute Cost of Mg Hydride - $0. 84/kg ~28] Cost of MgNi Hydride - $2, 20/kg ~28~ PAGENO="1240" 1234 Table 3.6 Cost, weight, and life factors used to calculate operating costs for a specified auto. Weight Cost Life 1 yr 1. Frame and Body 680. 4 kg $2250 2. Passenger and Baggage 362 kg None 3. Internal Combustion Engine and Drive Train 4 kg/kW $3. 31/kg 1 yr 4. Fuel Cell l8kg/kW $20-$160/kWl-5 yr 5. Electric Motor and Controller 4. 23 kgfkW $7. 34/kW 2 yr 6. Fuel Storage (kg) Hydrogen Liquid (Container) MgNi Hydride Mg Hydride Hydride Container 41. 3 + 3. ~ (Wt of H2)/0. 035 (Wt of H2)/0. 077 0. 136 x hydride wt. $15/kg 2 yr $2. 2/kg 2 yr $0. 84/kg 2 yr $3. 3/kg 2 yr Methanol 0. 136 x Fuel Wt S3. 3/kg 1 yr Gasoline 0. 18 x Fuel WI $3. 3/kg 1 yr PAGENO="1241" 1235 The equation used to calculate the energy requirements was taken from Austin [30] and modified to account for changing frontal area with car weight according to Ambs [31]. In- cluding an acceleration term the final equation used was: where dt ~t)V - c2 + (~ + V2 ] V is Velocity, km/h, P is Power at the wheels, kW, Wt is weight of Vehicle, kg, C1 - 11,820.55, C2 - 32.24025, C3 - 0.02, C4 = 3.0906 x l0~, and C5 - 1.3627 x lO_6. The power required during a constant velocity cruise was determined by solving the equation while setting dV/dt - 0. The power consumed during acceleration was determined by maintaining a constant P sufficient to accelerate a vehicle of selected weight to 64.4 km/h in 12 seconds. No power was consumed or recovered during the deceleration phase and only the distance traveled during this phase was of interest. The power required to accelerate a car of specified weight to 64.4 km/h in 12 seconds is shown on figure 3.1. Figure 3.2 shows the total energy required for the complete driving cycle of 8 hours versus the weight of the vehicle. In order to determine the size and thus the cost of the vehicle, a weight was assumed, and the motor sizes determined from the acceleration power require- ment divided by a drive train efficiency. Then the fuel storage capacity was determined by dividing the total energy requirements over the 8-hour period by the overall efficiency of the power unit. If the final calculated weight did not agree with the initial assumed weight, a new weight was assumed and the calculation repeated. In the case of the IC. engine, the drive train efficiency used was 80 percent. With the fuel cell the electric drive train efficiency together with the control unit was taken at 85 percent. Overall efficiency of the fuel cell and electric drive unit was taken as 50% [21]. The overall efficiency of the IC. engine and drive train was varied in the calculations. The fuel cell and electric drive unit weight was calculated by sizing the fuel cell to supply the total energy requirement of the 8-hour driving cycle, while the drive motor and control unit was sized to supply the required acceleration power. Lead-acid batteries were included to supply peak power requirements during the periods of acceleration. Figures 3.3, 3.4, and 3.5 show the results of the cost analysis for three different fuel costs. The calculated costs on these figures are only fuel and capital costs and do not include maintenance or insurance costs. The total cost of car operation was reduced to a cost per kilometer of operation by dividing the annual costs by the assumed 161,000 kilometers driven per year. The cost of producing liquid hydrogen was taken at 0.205 $/kg. This cost was chosen as a lower-intermediate value from table 1.3 (Chapter 1) to account for some boil-off losses (10 to 20 percent of liquefaction costs) and an intermediate liquefaction efficiency. PAGENO="1242" 1236 TOTAL CAR WEIGHT, lbs 0 1000 2000 3000 4000 30 I I I 25 - 5000 20 15 - c'J C E CD L) w F- C, C) CD F- CD CD - 40 35 30 25 CD 20 ~ V) CD = 15 - 10 -5 10 - 5 Power = 1.069 Power wt in + 3.277(wt) in kW kg 0 500 1000 1500 TOTAL CAR WEIGHT, kg 0 2000 2500 FIGURE 3.1 - Power Required at the Wheels to achieve 64.4 km/h in 12 seconds. PAGENO="1243" 1237 L) >- L) L~ CD uJ TOTAL CAR WEIGHT, lbs 0 1000 2000 3000 4000 5000 0 500 1000 1500 TOTAL CAR WEIGHT, kg 2000 2500 FIGURE 3.2 - Energy Required by Car for the Driving Cycle. PAGENO="1244" 1238 OVERALL IC. ENGINE & DRIVE TRAIN EFFICIENCY,percent 10 20 30 40 50 60 I I I I I .16 FUEL COST BASED ON LHV 9 Gasoline - $.OOS/kW-h ($1.5/lO6Btu) Methanol - $.OO5/kW-h ($1.5/lO6Btu) .14 H2 Gas - $.005/kW-h ($1.5/lO6Btu) 8 - H2Liquid - $.O11/kW-h ($3.3/lO6Btu) NOTE: Hydride Costs Assume Dissociation .12 7 Heats are Obtained from Waste Engine Heats. -6 - I- LU LU Q 5 - ~ Fuel Cell Life . (Liquid Hydrogen Fuel) 2 ~LH~ - .04 0 40 80 120 COST OF FUEL CELL, $/kW I I I I I I I I 02 160 200 FIGURE 3.3 - Cost of Car Operation; Low Cost Fuel. PAGENO="1245" 1239 FUEL COSTS OVERALL I.C. ENGINE & DRIVE TRAIN EFFICIENCY, percent 10 10 20 30 40 50 I .16 1 I Gasoline Methanol H2 Gas H2Liquid - $.O1/kW-h($3.OO/lOBtu) - $.O1/kW-h ($3.00/b Btu) - $.O1/kW-h ($3.OO/lO6Btu)- -$.O16/kW-h ($4.80/lO6Btu) NOTE: Hydride Costs Assume Dissociation Heats are Obtained from Waste Engine Heats. / LH2 9 8 0 40 80 ~20 COST OF FUEL CELL, $/kW Fuel Cell Life (Liquid Hydrogen Fuel) 14 .12 E - .10 I- w 0~ .08 I- cD L) .06 .04 .02 I I I I I I 160 FIGURE 3.4 - Cost of Car Operation, Medium Cost Fuel PAGENO="1246" 1240 OVERALL I.C. ENGINE & DRIVE TRAIN EFFICIENCY, percent 10 20 30 40 50 60 * 16 FUEL COSTS Gasoline - $.034/kW-h($1O/lO6Btu) Methanol - $.034/kW-h($1O/lO6Btu) H2 Gas - $.034/kW-h($lO/lO6BtuY H2 Liquid - $.O40/kW-h($11.8/lO6Btu) NOTE: Hydride Costs Assume Dissociation Heats are Obtained from Waste Engine Heats. *MgNi Hydride C F- LLi U- F- L) Fuel Cell Life (Liquid Hydrogen Fuel) 1 Yr. 14 .12 E &10 ~ F-- w .08 C F-- C .06 .04 Mg Hydride 2 0 40 80 120 160 200 COST OF FUEL CELL, $/kW 02 FIGURE 3.5 - Cost of Car Operation; High Cost Fuel. PAGENO="1247" 1241 The efficiency of the I.C. engine operating with gasoline or methanol fuel may approach 27 percent for a subcompact vehicle 119]. At least in the short term, the pollution controls on these engines may reduce their efficiency by 20 to 25 percent [1] resulting in an overall efficiency of 20 to 21 percent. Using hydrogen as a fuel for the I.C. engine should increase the efficiency of the engine to at least 27 percent. Although higher efficiencies F 11,12,33,38] than those obtained using gasoline as a fuel have been observed for hydrogen fueled I.C. engines, most of the higher efficiency is due to a higher part-load efficiency, an.~ at least for the car used in this calculation, the engine is of minimal size reducing the i~ajority of the part-load advantage. Gasoline costs are currently nearly $60/gallon (0.16 $12), especially for the no-lead gasoline scheduled for use with a majority of ēhe 1975 automobiles. Using 12.92 kW-h/kg as the lower heating value of gasoline and a density of 0.72 kg/Q, the current cost of energy is $0.017/kW-h or one-half the cost of fuel used on figure 3.5. Using a fuel cost of $.034/kW-h (figure 3.5) the most economical car usitog an IC. engine would be the hydrogen fueled car (efficiency of the engine is 27 percent versus 21 percent for methanol or gasoline fuel) with the fuel stored in magnesium hydride. The.only difficulty with this conclusion is that the theoretical performance of the magnesium hydride was used in the calculations, and indii~ations are that it may be necessary to either burn hydrogen to supply a portion of~the dissociation heat or that the hydride may poison or cake reducing its capacity [30]. Either one of the nonideal reactions of the magnesium hydride would increase the cost of operation of the car. Fuel cell powered cars with liquid hydrogen fuel would become competitive if fuel cells would cost less than $60/kW and have a life of 1 year or have a cost of less than $200/kW with a life of 5 years. Table 3.7 presents a breakdown of the operating costs obtained for an I.C. engine driven car and for a car powered by a fuel cell costing 160 $/kW. The gasoline and methanol fueled engines are assumed to be 20 percent efficient, the hydrogen IC. engines are taken at a modest 25 percent efficiency and the fuel cell power plant is assumed to be 50 percent efficient. The effects of the heavy weights and high capital costs are reflected in the cost of operation for the fuel cell system. High fuel costs increase the cost of operating the liquid hydrogen fueled I.C. engine driven car while the heavy weight of the MgNi in- creases the cost of operating the car using the MgNi hydrogen storage system. In the breakdown, the costs of fuel were taken from figure 3.5 (high cost fuel). No specific conclusion can be drawn from the economic study except that for low fuel costs the methanol and gasoline cars are the least expensive to operate. As the fuel costs increase, hydrogen fuel becomes more competitive. At high fuel prices, liquid hydrogen fuel with a fuel cell becomes more competitive if fuel cell costs can be reduced or if the life of a fuel cell can,be extended. If cost of operation becomes competitive, the choice of fuel must be hydroger~ because of the reduction in pollution from hydrogen-powered vehicles. As new engine designs evolve and cost factors ar~ defined the approach outlined herein can be used to compare alternate synthetic fuels. Hydrogen must be considered a strong contender at this writing due to the inflationary trend of automotive fuel costs. PAGENO="1248" Table 3.7 Breakdown of costs for the various power plant concepts Car B.C. Engine Drive Electrical Drive, Fuel Cell & Liquid 112 Liquid Gasoline Methanol Mg Hydride Hydrogen MgNi Hydride EffIciency, 1 20 20 25 25 25 50 Total Wt, kg 1181 1226 1316 1218 1597 1498 Total Energy Required for Driving Cycle, kW-h 78.9 81.3 85.6 80.8 102 90.54 Cost of Fool, Ceots/kn 3.086 3.181 2.68 2.985 3.194 1.777 Cost of Capital Body & Framc,Cents/km 1.609 1.609 1.609 1.609 1.609 1.609 Lead-Acid Batterles,cents/km 0.116 Fuel Cell, Cents/ks 0.864 Control & Electric Motor Cents/ks 0.168 IC. Engine, Cents/km 0.298 0.310 0.265 0.246 0.318 Fuel Tank, Cents/km 0.014 0.029 0.144 0.360 0.382 0.244 Totals 5.007 5.129 4.721 5.209 5.503 4.778 PAGENO="1249" 1243 3.6 REFERENCES [1] Transportation Energy Panel, Research and development opportunities for improved transportation usage, Department of Transportation, Report No. DOT-TSC-OST--73-l4, (Sept. 1972). 2] Zabetakis, M. G., Flammability characteristics of combustible gases and vapors, Bureau of Mines Bulletin No. 627 (1965). [3] Marks, L. S., Mechanical Engineers Handbook, McGraw Hill Book Company Inc. New York, N.Y. (1951). [4] Fire-Hazard Properties of Flammable Liquids, Gases, and Volatile Solids, National Fire Protection Association, Ho. 325 (May 1960). [5] On an investigation of hazards associated with the storage and handling of liquid hydrogen, Final Report C-61092, Contract No. AF 18(600)-1687, Prepared by Arthur D. Little, Inc., DDC Access. No. AD 324194, 137 pages (Mar. 1960). [6] Billings, R. E., and F. E. Lynch, History of hydrogen-fueled internal combustion engines, Billings Energy Research Corp., Publication No. 73001 (1972). [7] Weil, K. H., The hydrogen I.C. engine- its origins and future in the emerging energy-transportation-environment system, Proceed. of the 7th IECEC, 1355-1363 (1972). [8] Gwynne, P., The hydrogen car, New Scientist, Vol. 60, No. 868, 202-3 (Oct. 1973). [9] Billings, R. E., and F. C. Lynch, Performance and nitric oxide control parameters of the hydrogen engine, Billings Energy Research Corp., Report No. 73002 (1973). [10] Murray, R. G., R. J. Schoeppel, and C. L. Gray, The hydrogen engine in perspective, Proceed, of the 7th IECEC, 1375-81 (1972). [11] Swain, N. R., and R. K. Adt Jr., The hydrogen-air fueled automobile, Proceed, of the 7th IECEC, 1382-87 (1972). [12) Adt, K. R. Jr., 0. L. Hershberger, J. Kartage, and M. R. Swain, The hydrogen-air fueled automobile engine (Part 1), Proceed. of the 8th IECEC, 194-7 (1973). [13] Modrey, J., Hydrogen powered bus, a small distribution bus powered by a hydrogen fueled engine, Brochure furnished in a private communication from J. Modrey, Purdue Univ., Lafayette, md. (1974). [14] Stephen, R. D., N. A. Henein, and T. Singh, Emissions characteristics of the Stirling and other engines, Proceed. of the 7th IECEC, 887-95 (1972). [15) Michels, A. P. J., CVS test simulation of a 128 kW Stirling passenger car engine, 7th IECEC, 875-886 (1972). [16] Scott, R. B., W. H. Denton, and C. M. Nicholls, Technology and uses of liquid hydrogen, The MacMillan Company, New York, N.Y. (1964). [17) Mulholland, D. R., L. W. Acker, H. H. Christenson, and W. V. Gough, Flight investigation of a liquid-hydrogen fuel system, NACA, Report No. N71-75l21 (1957). [18] Lueckel, U. J., I. G. Ekiund, and S. H. Law, Fuel cells for dispersed power generation, Transactions of the Power App. & Systems, IEEE, PAS-92 (1973). [19] Berger, C., Ed., Handbook of fuel cell technology, Prentice-Hall, Inc., Englewood Cliffs, N.J. (1968). 62-332 0 - 76 - 79 PAGENO="1250" 1244 [20] Salihi, J. T., Energy requirements for electric cars and their impact on electric power generation and distribution systems, IEEE Trans. on Industrial Applications, Vol. IA-9, No. 5 (1973). [21] Kordesch, K. V., Hydrogen-air/lead battery hybrid system for vehicle propulsion, Journal of the Electrochemical Society, 812-17 (May 1971). [22] Rice, W. K. and D. Bell III, Status of shuttle fuel cell technology program, Proceed. of IECEC, 390-95 (1972). [23] Marks, C., E. A. Rishavy, and F. A. Wyczalek, Electrovan-a fuel cell powered vehicle, SAE Transactions, Vol. 76, 992-1002 (1968). [24] Kyle, H. L., K. J. Cairns, and D. S. Webster, Lithium/sodium batteries for off-peak energy storage: A preliminary comparison of energy storage and peak power systems, Argonne National Laboratory, Contract W-3l-l09-Eng-38, Report No. XNL-7958 (1973). [25] Billings, R., Hydrogens potential as an automotive fuel, Cryogenics and Industrial Gases, Vol. 9, No. 1, 23-5 (1974). [26] Private communication with J. J. Hibel of Beech Aircraft Corporation, Boulder, Cob. (1974). [27] Booth, L. A., J. 0. Balcomb and F. J. Edeskuty, A combined nuclear and hydrogen energy economy-a long tern solution to the world's energy problem, Proceed. of the 8th IECEC, 396-403 (1973). [28] Cummings, D. L., and G. J. Powers, The storage of hydrogen as metal hydrides, md. Eng. Chem., Process Des. Develop. Vol. 13, No. 2, 182-92 -(1974). [29] Wiswail, R. H., and J. J. Reilly, Metal hydrides for energy storage, Proceed of the 7th IECEC, 1342-48 (1972). [30] Austin, A. L., A survey of hydrogen's potential as a vehicular fuel, University of California, Lawrence Livermore Laboratory, Report No. UCRL-5l228 (Jun 1972). [31] AmTs, L. L., Passenger car design influences on fuel consumptl2n and emissions, Proceed. of the 8th IECEC, 227-231 (1973). [32] Billings, R., N. Baker, F. Lynch, and 0. Mackay, Ignition parameters of the hydrogen engine, Proceed. of the 9th IECEC, 487-92 (1974). [33] Stewart, W. F., F. J. Edeskuty, K. D. Williamson, Jr., and H. M. Lutgen, Operating experience with a liquid hydrogen fueled vehicle, Book, Advances in Cryogenic Engineering, Vol. 20 (Ed.) K. 0. Timmerhaus (Plenum Press, Inc., New York, N.Y., 1975) - to be published: See also Stewart, W. F. and F. J. Edeskuty, Alternate Fuels for Transportation, Part 2: Hydrogen for the Auto- mobile, Mech. Engr., 22-28 (June 1974). [34] - Private communication with W. D. Van Vorst of Univ. of Calif., Los Angeles, Calif. (1974). [35] Private communication with H. M. Lutgen of Minnesota Valley Engineering Co., New Prague, Minnesota (1974). [36] Griffith, K. 3., Letter to the editor concerning hydrogen fuel, Nature, Vol. 248, 458 (March 1974). [37] Bauer, W., S. C. Keeton, L. N. Tallerico and C. Landram, Hydrogen as a vehicular fuel, Internal Sandia Rept. SLL-73-0053 (Aug. 73). [38] Hoehn, F. W., and M. W. Dowdy, Feasibility demonstrations of a road vehicle fueled with hydrogen-enriched gasoline, Proceedings of the 9th IECEC, 956-64 (1974). PAGENO="1251" 1245 CHAPTER 4 SURVEY OF MATERIALS FOR HYDROGEN SERVICE 3. G. Hust 4.0 SUMMARY Hydrogen related materials requirements involve primarily: hydrogen embrittlement resistance, high and low temperature strength, wear and corrosion resistance, hydrogen and oxygen compatibility, and insulating materials. The problem of hydrogen-environment embrit- tlement, relatively unique to hydrogen service, introduces severe materials requirements and pervades essentially all phases of hydrogen production, transfer and storage, and applica- tions. Low-cost, high-strength materials which are also embrittlement immune and resistant to corrosion, will be necessary in hydrogen production facilities and for transfer and storage systems. A strong need also exists for low-cost, light-weight storage systems and insulating materials for portable applications, such as for fuel tanks aboard automobiles and aircraft. Composite materials are strong candidates for these applications. Many materials, of course, exist which are applicable to hydrogen service, but low-cost materials are needed. In some in- stances, large uncertainty exists as to the compatibility of materials with hydrogen, pri- marily because of the embrittlement phenomena. In other cases, such as in proposed hydrogen production techniques, the materials problems cannot yet be defined because of uncertainty as to the method or process which will be adopted. Materials research should be directed toward: (a) compilation and critical analysis of existing low temperature, ambient tempera- ture, and high temperature mechanical and thermal property data and embrittlement data for candidate structural materials, (b) compilation and critical analysis of low temperature insulation data, (c) establishment of standard embrittlement test procedures suitable for pertinent applications, (d) establishment of standard insulation test procedures and standard reference materials of insulation to facilitate these test procedures, (e) mea- surement of mechanical properties, thermal properties, embrittlement, and permeation of metals and non-metals (especially plastics) as indicated by (a), (f) measurement of thermal conductance of insulating materials using standardized test procedures, and (g) develop- ment of light-weight, high-strength, embrittlement immune materials for high pressure structural applications, of low-cost efficient insulations and development of hydrogen- oxygen catalytic materials. 4.1 INTRODUCTION The fossil fuel energy shortage has created strong interest in alternate sources of energy and methods of energy storage. Fossil fuels, such as gasoline, natural gas, oil, and coal are portable and are used directly for transportation as well as for heating and electric power generation. Alternate sources of energy, such as nuclear, solar, and geo- thermal, are less portable or not portable at all. Their application tends toward an electrical economy which is less applicable to transportation needs. If society is to retain all current modes of transportation, it is clear that a readily portable and storable energy carrier is needed. Fossil fuels have been the basis for such PAGENO="1252" 1246 an energy carrier in the past, but as our resources are depleted, an alternate comparable energy carrier must be developed. One of several portable energy carriers is hydrogen fuel [fl It can be produced from water and is available almost anywhere on earth. This storable energy carrier is also ecologically clean and its closed re-use cycle, H20 -c + 0 -~ H20, can be measured in weeks as compared to the effectively open cycle of fossil fuels, measured in millions of years, if at all. It is emphasized that water is not an energy source but only a material which can be used effectively to produce an energy carrier (hydrogen fuel). The energy required to produce hydrogen by splitting water is theoretically comparable to the energy carried by the hydrogen produced. Scores of papers have been written describing the production, storage and transmission, and applications of hydrogen as a fuel. Some of these are rather non-technical and specula- tive in nature, others relate principally to the aerospace program. The more detailed docu- mentation on the feasibility, economics, and applications of hydrogen as a fuel for commer- cial and domestic use are by Hord [1], Gregory [2-6], De Beni and Narchetti [7,8], Winsche, et al [9], Jones [10], and Maugh [111. The most inclusive treatment is by Gregory [2]. These and other papers suggest that no insurmountable technical materials problems exist for the production, transfer and storage, and general use of hydrogen as a fuel. As a matter of fact, hydrogen has already been used in ground vehicles and aircraft to a limited extent, quite extensively as a 50% to 80% component in a gas mixture for domestic use in the form of "town gas" or manufactured coal gas, and most extensively in the aero- space program. The materials limitations are based primarily on economic considerations as described in later sections of this paper. In anticipation of the development of a hydrogen fuel economy, we will consider materials problems associated with the production, transfer, storage, and use of immense quantities of gaseous, liquid, and possibly solid hydrogen, see for example reference [12]. The purpose of this paper is to review potential material (primarily structural and insulat- ing materials) requirements involved in the production, transfer, storage, and use of hydrogen, including the containment of related chemicals in hydrogen applications. This review encompasses the containment of hydrogen under static as well as dynamic conditions, at temperatures from near absolute zero to high temperatures, which in some proposed devices exceeds the limits of present production materials, and at pressures from atmospheric conditions to thousands of atmospheres. In addition, attentian is directed to materials requirements in the handling of oxygen by-product and the compatibility of materials in contact with some of the more corrosive chemicals used in the productior nd applications of hydrogen. In section 4.2, hydrogen related materials properties are discussed, e.g., mechanical, thermal, and compatibility propertits. Although a wide range of conditions is involved in a hydrogen economy, emphasis is directed toward those facets which are most unique to domestic and commercial applications of hydrogen. A lengthy section on hydrogen embrittle- mont is included to emphasize the significance of this phenomena in ambient as well as high temperature systems design. Other high temperature and pressure effects are slighted, PAGENO="1253" 1247 since associated problems are common to other industrial processes and concomitant research and development. Low temperature insulation requirements and developments are reviewed. Sections 4.3 through 4.5 are concerned with systems design requirements dictated by material embrittlement, low temperature effects, and compatibility, in hydrogen production, transfer and storage, and applications. Emphasis is directed toward those materials in direct contact with hydrogen, such as metal and plastic pipes, metal and composite storage vessels, seals, bearings, propulsion systems, and domestic appliances. Low temperature insulating materials and systems are discussed. A materials survey similar to this is currently in progress at Stanford Research Institute under the direction of Neville Daniels [13]. Areas of emphasis will undoubtedly differ in these studies and in some instances viewpoints may be in conflict, but it is believed that the results of these two studies will supplement each other, resulting in a more thorough overview. Discussions have been conducted with Daniels and his associates regarding common areas of interest. The quest for data on materials requirements included: computer searches of the NBS Boulder-Cryogenics Division Data Center, the NASA Cleveland Data Bank, and the Smithsonian Scientific Information Exchange Work-In-Progress File for information on hydrogen related problems, systems, and current research. Abstracts from the NASA Research and Technology Operating Plan Summary (1972) and An Inventory of Energy Research by ORNL (1972) were also searched. Approximately 1000 references resulting from these searches relating to hydrogen service and materials research were obtained and reviewed. In addition, discussions, both personal and by phone, were held with several dozen experts in materials research and cryogenic systems development. Considerable information was also obtained from members of the NBS Cryogenics Division. The author has attempted to give due consideration to all pertinent aspects of a hydrogen economy, but it is unavoidable that a review of this scope reflects to some extent the author's personal interests. This work, therefore, should be considered a source of information gathered from workers in each discipline as reported in the published literature, contract reports, and summaries, and through personal contacts with these workers. 4.2 HYDROGEN RELATED MATERIALS PROPERTIES Pertinent material properties can be divided into mechanical, thermal, electrical, and chemical properties. Each of these may have unique importance in particular applications. In structural design, economic, fabrication, and mechanical property considerations require the highest priority. In the presence of appreciable temperature gradients such as in the containment of cryogenic hydrogen, thermal properties (e.g., thermal conductivity, thermal expansion, and specific heat) are critical and significantly affect material selection. Chemical properties are considered significant here only in-so-far as they influence perti- nent mechanical properties. Of the previously mentioned range of conditions, temperature is the most significant from the standpoint of material property variation. Solids generally become stronger but PAGENO="1254" 1248 less ductile as temperature decreases. For many metals, this loss in ductility is suffi- cient to eliminate them from low temperature applications (see, for example, Pearson [14]). The thermal conductivity and thermal expansion of most metals change appreciably with tem- perature, especially at low temperatures. Corrosion resistance decreases with increasing temperature and is a potentially serious problem in some of the proposed high temperature hydrogen production methods. Because of their small size, hydrogen atoms readily dissolve into and diffuse through most materials. The diffusion and permeation of hydrogen in metals is a significant aspect of hydrogen embrittlement in metals. Hydrogen embrittlement produces severe mechanical property degradation of many metals and often results in premature structural failure by brittle fracture. It is most significant at ambient temperatures, less so at high tempera- tures, and negligible at cryogenic temperatures. Hydrogen-reaction embrittlement (see section 4.2.2) can be significant at high temperatures and in hydride storage applications. The design of equipment for hydrogen service must include consideration of material compatibility, property variations (primarily as a function of temperature), and the degradation of these properties due to hydrogen embrittlement. The following sections elaborate on these property variations, concomitant design considerations, and related problem areas. 4.2.1 Temperature Effects Excellent reviews and data compilations have been published on the temperature varia- tion of mechanical properties of metals [15-27], polymers [18,21,23,28,291, and other non-metals [18,21,23]. Two basic requirements of a structural material that must be ful- filled are: (1) it must support a sufficient load (generally with a minimum deflection) and (2) it must be tough but not brittle. Of course, it should also be economic and readily fabricated. The first requirement implies a high strength material while the second implies ductility. For many materials, these requirements are somewhat in conflict, since as strength increases, ductility often decreases. At high temperature the increased ductility and lowered strength of most materials are significant factors in material selection. At low temperature the brittle behavior of materials is most important, and thus, fracture mechanics is of great importance. A myriad of mechanical properties of significance in material selection can be cited, such as hardness, modulus, strength, ductility, creep, fracture toughness, yield stress, offset strain, etc. Which of these are most important is determined by the particular applications. Often equipment must be designed to operate alternately at ambient and low temperatures or ambient and high tem- perature, thus requiring acceptable properties over extended temperature ranges. The temperature dependence of some of the more important mechanical properties of transition metals can be classed according to the crystalographic structures, face centered cubic (fcc), body centered cubic (bcc), and hexagonal close packed (hcp). Fcc transition metals are generally lower in strength but tend to remain ductile at low temperatures. Structural metals for low temperature applications are usually chosen from the fcc class, e.g., aluminum, copper, and nickel alloys as well as austenitic stain- less steels. The fcc metals generally have low yield stress relatively independent of PAGENO="1255" 1249 temperature, but the yield stress can be improved by cold work. Bcc transition metals are hard, have high melting points, and thus are of considerable use at high temperatures. Iron, the most important and cozmmn of these, undergoes a crystal structure phase change at 910CC. The fcc, high temperature, or f-phase exists above 910CC while the bcc, low temperature, or a-phase exists below. Bcc metals tend to become brittle at low temperatures, and thus are usually avoided for low temperature applications. Through the addition of various elements to iron, the o-'y transition temperature can be controlled. Additions of chromium, tungsten, vanadium or silicon among others raises the transition temperature and tends to stabilize the bcc structure. Additions of manganese, nickel, cobalt, or copper among others lowers the transition temperature resulting in a more stable fcc structure. With sufficient nickel, for example about 42%, a fully stabilized fcc alloy (austenitic steel) is obtained which remains stable to the lowest temperatures measured. The hcp transition metals are not as readily classified as the bcc and fcc metals; some of them behave more like bcc metals while others have the properties of f cc metals. For example, tungsten is brittle at low temperatures, and zirconium and titanium remain ductile at low temperatures. Typical stress-strain curves for fcc and bcc metals are shown in figure 4.1 (data obtained from Fickett [19] and Kasen [39]). Of the many physical properties, only a relatively few, other than mechanical properties, are important in structural applications. Probably the most significant are thermal expan- sion and density. Of lesser, but significant, relevance are thermal conductivity, specific heat, and thermal diffusivity. In fewer instances, electrical resistivity and dielectric properties are important in design. The most extensive effort for the compilation of thermal properties of materials is the on-going work at the Thermophysical Properties Research Center, Purdue University, under the direction of Touloukian [30]. Other excellent compilations and papers are: thermal expansion of alloys by Clark [31], thermal properties of polymers by Schramm, et al. [.29], specific heats by Corruccini and Gniewek [32], and thermal conductivity of materials by Childs, et al. [33]. Reviews on thermal properties of metals and non-metals are abundantly available; only the texts by Tye [34], Childs, et al. [33], and Touloukian [30] are cited. Density data on metals can be found in the ASM Metals Hand- book [16]. A few summarizing remarks on thermal and electrical properties are given here. The thermal and electrical properties of metals and non-metals are generally strongly dependent on temperature. The thermal and electrical conductivities of pure metals at low tempera- tures are strongly dependent on the concentrations and types of impurities. The heat treatment or anneal condition also can significantly affect the low temperature values for both pure metals and alloys. Figure 4.2 illustrates the general temperature dependence of thermal conductivity for metals. Specific heat and thermal expansion are relatively insensitive to small composition changes In metals but heat treatment can produce signifi- cant changes in thermal e~cpansion. See, f or example, Clark's [31] data on AISI 633 annealed and precipitation hardened steel. High temperature properties are less sensitive to composition and heat treatment. Comparative behavior of thermal expansion is illustrated in figure 4.3. PAGENO="1256" 1250 180 160 ~ 140 E 120 1100 ~80 U, -`~ 60 w t 40 20 0 STRAIN (Glass-Cloth Composites only) 0.04 0.08 0.12 FIGURE 4.1 Tensile behavior of bcc and fcc metals and glass- reinforced composites. 0 0.6 0.8 STRAIN PAGENO="1257" 1251 TEMPERATURE, K 3 5 10 50 100 300 TEMPERATURE, K Figure 4.2 Thermal conductivity for several classes of materials as a function of temperature. PAGENO="1258" z 0 U, x U, 1252 0 100 200 300 TEMPERATURE, K Figure 4.3 General behavior of the thern~al contraction for several classes of materials. PAGENO="1259" 1253 Electrical resistivity data for pure metals are relatively abundant. The text by Meaden [35] contains extensive resistivity data and in addition is an excellent introduc- tory treatise. Hall [36,37] has compiled the low temperature resistivity of selected pure metals. Electrical resistivity data sources for alloys are much more scarce, probably because of the lack of theoretical interest. A paper by Clark [38] contains low tempera- ture data for selected alloys at low temperatures. Non-metals, like metals, tend toward brittleness as temperature is lowered; a few non-metals remain sufficiently ductile at low temperatures to be structurally useful, e.g., polytetrafluoroethylene (TFE) and hexaflouropropylene (FEP). Creep in polymers is relative- ly large and can be a problem in certain applications. Non-metals often are useful in hydrogen applications involving insulations, supports, bearings, seals, and structural reinforcing composites. A review of the state-of-the-art on composites is presently being prepared by Kasen of this laboratory [39]. Composites range widely in mechanical properties depending strongly on fiber orientation, matrix material, resin, temperature, etč. In general, they have very high strength-to-weight ratios and may find extensive applications in high-pressure and low-weight vessels and pipes. Typical stress-strain, thermal conduc- tivity, and thermal contraction data are illustrated in figures 4.1, 4.2 and 4.3, respec- tively. An excellent review of the mechanical properties of non-metals, including polymers, foams, ceramics and glasses, and composites is given by Wigley [23]. Extensive polymer property data are tabulated in the Encyclopedia of Polymer Science and Technology [40], by Schramm, et al. [29], and reviewed by Serafini [28]. 4.2.2 Hydrogen Embrittlement, Diffusion and Permeation As indicated earlier, hydrogen readily diffuses into most engineering materials. The presence of atomic and molecular hydrogen can cause significant degradation of the mechanical properties, i.e., embrittlement, of most metals. Embrittlement is the most severe technological problem encountered in the containment of gaseous hydrogen. A vivid example is the failure of several 5000 psi, 1300 cubic foot hydrogen gas vessels [41]. One of these vessels developed a 50 inch long crack ata weld seam. Three similar hydrogen containing vessels failed, while several identical nitrogen containing vessels were operated without incident for several years. Such incidents could be avoided through the use of more compatible materials or more sophisticated vessel design, but this may not be economically feasible in a larger scale commercial facility. Jewett, et al. [41] and Voth [42,43] describe many failures due to material embrittlement in vessels and gauges. Failures have been observed at as little as one-tenth design pressure. These incidents are cited to emphasize the need for material research and development so as to obtain hydrogen compatible, inexpensive materials. Although it has been known for about 100 years that hydrogen can seriously degrade the mechanical properties of metals [44], the exact mechanisms by which this occurs are not clearly understood. It is now believed that hydrogen embrittlement can be classified into three categories: (1) hydrogen-reaction embrittlement, (2) internal-hydrogen embrittlement, and (3) hydrogen-environment embrittlement. Hydrogen-reaction embrittlement occurs as a PAGENO="1260" 1254 result of chemical reaction between hydrogen and the base metal or some alloying element of the metal. Metals such as titanium, zirconium, niobium, and tantalum (exothermic occluders) form irreversible embrittling hydride phases. The decarburization of steels and the for- mation of high-pressure water vapor in copper voids and methane in steel voids are other examples of hydrogen-reaction embrittlement. Both internal and environmental-hydrogen enthrittlement are due to hydrogen atoms dissolving into the metal. The most widely researched area of internal embrittlement is that caused by electrolytic charging such as in a plating, cleaning, or pickling baths. Internal-hydrogen and hydrogen-reaction embrittlement problems are often encountered in metal and petrochemical processing facilities. Any hydrogen containing chemical solution is capable of producing internal-hydrogen embrittlement. Hydrogen-environment embrittlement signifies the degradation of mechanical properties occuring due to the presence of hydrogen at the surface of the metal. This is also referred to as external-hydrogen embrittlement. Both internal and external-hydrogen embrittlement are reversible so long as the hydrogen is removed before crack formation coimnences. Internal hydrogen can be removed by high temperature heat treatment. Hydrogen-environment embrittle- ment, although probably closely related to internal-hydrogen embrittlement, is the most unique to a hydrogen economy and is the primary subject of this section. Several reviews and compilations of data on hydrogen-environment embrittlement exist [41,45-64]. It is clear from these reviews that controversy exists as to the exact mechanism operative in hydrogen-environment embrittlement. One argument leads to the conclusion that hydrogen-environment embrittlement is distinct from internal-hydrogen embrittlement, and other arguments lead to the conclusion that both are manifestations of the same mechanism. The main argument for distinctly different mechanisms is that delayed failure, failure at constant stress below the normal strength of the metal after a time which may be hours or days, occurs only through internal-embrittlement. Embrittlement due to hydrogen-environ- ment is immediate, and no increase in embrittlement is seen with exposure times as long as 100 days [41,54,60,61]. Otherwise, the behavior of the two types of embrittlement is quite similar. It is noted that early internal embrittlement studies on Inconel 718 indi- cated no susceptibility to embrittlement, but recent hydrogen environment studies showed Inconel 718 to be severely embrittled [411. The degree of hydrogen-environment embrittlement is dependent on the base metal and its alloying constituents, the microstructure of the metal, strain rate, the surface condi- tion of the metal (cracks, notches, pits, etc.), stress, the strength level of the metal, impurities present in the hydrogen environment, and probably other parameters not yet in- vestigated. It has often been suggested that, at least in the case of steels which are the most thoroughly investigated metal class, metals with a fcc structure are relatively immune to embrittlement while metals with a bcc structure are severely embrittled. It has been shown more recently that the crystal structure is less significant than the atomic struc- ture [52]. More specifically, Louthan [52] has shown a close relationship between hydrogen solubility, and subsequently the degree of embrittlement, and the density of states at the PAGENO="1261" 1255 Fermi surface. Chandler and his associates at Rocketdyne [41,54,60,61] have compiled and reviewed all but the most recent hydrogen-environment embrittlement data. To avoid an overwhelming list of references, their reviews are the principal source of information here. The Rocketdyne group has shown that the degree of embrittlement is approximately pro- portional to the square-root of pressure until saturation occurs, which is generally several thousand pounds per square inch. Internal-embrittlement generally peaks near ambient tempera- tures and falls off both at high temperatures and at low temperatures. No hydrogen-environment embrittlement is expected at liquid hydrogen temperature with common structural materials. At higher temperature, such as encountered in engines, burners, and proposed hydrogen pro- duction equipment, both hydrogen-environment and reaction embrittlement problems are likely [41,65,66]. In addition, at high temperatures and pressures, the containment material will become saturated with hydrogen. If cooldown of the equipment is not controlled, to allow the internal hydrogen to escape by permeation, classical internal-hydrogen embrittlement may result at ambient temperature. Groeneveld [67] has observed blistering of A387 and A52 steels after cooldown from a high temperature and pressure hydrogen environment. Troiano [68] indicates that degassing by cyclic temperature control to remove hydrogen in refining operations is standard procedure. Gray [49] notes that embrittlement may also occur in a liquid hydrogen vessel if the ullage space material approaches ambient temper- ature. Rate of strain is an important parameter in the degree of embrittlement exhibited. Low strain rates promote maximum embrittlement. Smooth surfaces are least susceptible to embrittlement. Metals conditioned to high strength levels are more susceptible to embrittle- ment than their lower strength counterparts. This effect is especially important in weld- ments or localized hard spots. Table 4.1 illustrates the relative degree of embrittlement of metal classes. The relative scale used is the same as that defined by Chandler, et al. [41]. Table 4.2, taken from a most recent publication by Chandler and Walter [69], illus- trates more specifically the embrittling effects on metals as indicated by notched and unnotched strength ratios and unnotched ductility. The purity of the hydrogen environment can have profound effects on the degree of embrittlement. Small amounts of oxygen, in some instances, have totally destroyed the enbrittling capability of hydrogen. Small additions of SO2, CO, and CS2 are also effective in inhibiting hydrogen embrittlement. Chandler, et al. [41) and Fidelle, et al. [70] have investigated the effects of metallic and oxide coatings to inhibit embrittlement. Chandler, et al. [41] feel that an effective coating must have low permeability, be non-porous, adhere well to the substrate, and be ductile or self-healing. He has found that electro- plated coatings of copper, gold, and silver are effective barriers. Chandler [71] is continuing his work on aerospace alloys and is also carrying on discussions with the Institute of Gas Technology to determine the significance of embrittlement on pipeline materials. He indicates that, although embrittlement is most important at ambient tempera- tures, creep and low cycle fatigue are affected at high temperatures. A286 stainless steel, for example, is relatively immune at room temperature but is appreciably affected at elevated PAGENO="1262" 1256 Table 4. 1. Relative degree of hydrogen-environment embrittlement of classes of metals. Degree of Embrittlement Materials Characterization Extreme High strength steels Large decrease in notch Nickel-base alloys strength and notched and unnotched ductility. Some decrease in unnotched . strength. Propagation of surface cracks. Severe Ductile, lower- strength steels Pure nickel Titanium alloys Considerable reduction of notch strength and unnotched and notched ductility. No reduction of unnotched strength. Propagation of surface cracks. Slight Metastable 300 series stainless steels Beryllium-copper Pure titanium Small decrease in notched Strength and unnotched ductility. Failure of unnotched specimens from within. Negligible Aluminum alloys Stable austenitic stainless steels Copper. Essentially unembrittled with no surface cracks. PAGENO="1263" 1257 Table 4.2 Embrittlement of Metals by 68.9 MN/rn2 (10,000 psi) Hydrogen at Ambient Temperature, Chandler and Walter { 69 1. Material Strength Ratio, H2/He Unnotched Ductility Elongation RA* Percent Percent Notched Unnotched He H2 He H2 (Kt=8.4) 18 Ni-250 MAR 410 SS 1042 QT 17-7PH SS Fe-9Ni-4Co-0. 2C H-li Rene 41 Electroformed Ni** 4140 Inconel 718 440 C Ti-6Al-4V (STA) 430 F Nickel 270 A-515 HY-l00 A-372 Class IV 1042 Normalized A- 53 3-B Ti-6Al-4V (annealed) AISI 1020 HY-80 Ti-SAl-2.5Sn ELI ARMCO Iron 304 ELC SS 305 SS Be-Cu Alloy 25 310 SS Titanium A-286 7075-T73 Al Alloy Incoloy 903~ 316 SS OFHC Copper NARIoy_2r* 606l-T6A1 Alloy 1l00-OAl 0.12 0.68 0.22 0.79 0.22 0.23 0.92 0.24 0.86 0.25 0.57 0.27 0.84 0.31 0.40 0.96 0.46 0.93 0.50 0.40 0.58 0.68 0.70 0.73 0.73 0.74 0.75 0.78 0.79 0.79 0.80 0.81 0.86 0.87 0.89 0.93 0.93 0.95 0.97 0.98 1.00 1.00 1.00 1 10 1.10 1.40 8.2 0.2 55 2.5 15 1.3 60 12 17 1.7 45 2.5 15 0.5 67 15 8.8 0 30 0 21 4.3 29 11 14 2.6 48 9 17 1.5 26 1 -- -- 3.2 0 22 14 64 37 56 52 89 67 42 29 67 35 20 18 76 63 20 10 53 18 59 27 66 33 68 45 70 60 45 39 83 50 78 71 78 75 72 71 64 62 61 61 44 .43 37 35 50 47 72 75 94 94 24 22 61 66 93 93 Identification of a manufacturer and a manufacturer s product in this table has been/necessary to make the results of this work meaningful and in no way implies a recommendation or endorsement by the National Bureau of Standards. RA=reduction in area Tested in 48.3 MN/m2 (7000 psi) H Rockwell International Corporation Trademark; tested in 2 40 MN/m2 (5800 psi) H2 PAGENO="1264" 1258 temperatures (see also [72]). He also notes that little work has been done on crack growth at high temperatures. Chandler [41] says it is safest to assume a metal enbrittles unless proven otherwise. Only aluminum alloys, austenitic stainless steels, and copper have been shown to be reasonably immune. Hydrogen embrittlement does not significantly affect elastic properties; most affected are tensile ductility, notch strength, fatigue, and crack behavior and creep. Vented multilayer vessels have been used successfully to reduce failures due to embrittlement [73,74]. Filament-wound containers with an impermeable metal liner have been developed for aerospace applications [75-81]. These may be very useful in a hydrogen economy. Life prediction for high temperature hydrogen materials, based upon Nelson curves [82], has been common procedure to prevent unexpected failure. Extrapolation of these curves should be avoided. No evidence has been presented which indicates serious embrittling effects of hydrogen on non-metals. However, very little work has been done in this area; the only work on non-metals compatibility is being done at White Sands Test Facility, New Mexico [83,84]. Preliminary results indicate that, of room temperature vulcanizing silicone rubber (RTV), polyvinyl chloride (PVC), polytetrafluoroethylene_hexOflUOrOprOPylene copolymer (FEP), polytetrafluoroethylene (TFE), glass filled TFE and cellulose acetate butyrate (CAB), only RTV is adversely affected by hydrogen. A slight charring of RTV was observed during hydrogen environment impact tests. Thermal conductivity and electrical resistivity of pure metals can be strongly affected by impurities in solids, including gases such as hydrogen. In impure metals and alloys the effect is small and in most cases undetectable. Other thermal properties are not significantly dependent on hydrogen content. Structural design will not significantly depend on the effect of hydrogen on thermal and electrical properties. Since hydrogen diffuses and permeates through materials and flows through crevices more readily than other gases, the often mentioned, potential problem of hydrogen leakage deserves attention. The permeation of hydrogen through metals is well below the level which would cause any safety or economic difficulty. Permeation through polymers, although much larger than through metals, is not expected to be a problem in plastic gas pipes. Figure 4.4 illustrates the approximate hydrogen permeabilities of metals and polymers. The principal area of con- cern for hydrogen leakage is in seals and cracks. Beck [46] reviews methods of low level hydrogen detection and quantitative measurements. These methods are useful both for per- meation studies and for hydrogen content determinations. Powell, et al. [85,87] have recently described a very sensitive hydrogen content measuring device. Berman, et al. [88] have developed a thermochemical technique which is precise to 0.1 ppm, rapid, and is appli- cable to in-situ measurements. Jankcwsky [89] has compared other test methods of hydrogen detection in metals. 4.2.3 Insulation As envisioned, the hydrogen economy would involve large quantities of liquid hydrogen for convenient transport by ocean tankers, trucks, and by rail, for convenient storage, and for use in ground vehicles and aircraft. Liquid hydrogen, because of its low boiling tem- perature (20 K, -253°C) and its low volumetric latent heat of vaporization (7.5 kcal/liter), PAGENO="1265" 1259 0 1' 0 C U - ,0~. U >~ I- C E ~ U - DC - U m C U ~ o &~, >- F- - ,-~ _J I - CD 0 ~ U w >~ I- w ~D 0. 0 CD ~0 I- CD 4., 0 0. Figure 4.4 Permeability ranges of metals and polymers (ambient temperature). 62-332 0 - 76 - 80 PAGENO="1266" 1260 must be extremely well insulated to minimize fluid boil-off losses. Except for the relatively recent advent of multilayer insulation, few significant improvements in economic insulation technology are noted. Most of the recent hydrogen- insulation work is directed toward improved insulation systems rather than material develop- ment [73,74,90-110]. Recent reviews on insulation technology are extensive [73,111-115]. These describe systems of measurement, give comparative data on the thermal conductance of various insulations, comparative costs, weight, etc. Insulations commonly used for liquid hydrogen~ storage are vacuum with liquid nitrogen shield, and evacuated foams, perlite, silica gel, and superinsulation. Comparative heat losses are illustrated for these in figure 4.5. Thermal conductance is illustrated in figures 4.2 and 4.5. For the lowest conductance insulations, such as superinsulation, a large proportion of the heat loss is through thermal bridges. Examples of these thermal bridges are structural supports, seams, and holes through which thermal radiation penetrates. Not all systems will require the same degree of insulation quality. This is determined primarily by a trade-off between insulation system (material) cost and boil-off losses or hold time. For example, in an automobile storage vessel, the relative boil-off may be quite high because the tank is generally emptied in a few days at normal rates. In a large sta- tionary storage vessel, relative boil-offa need to be small because of the large absolute losses involved. Thus, various insulation qualities will be required for different appli- cations. Although relatively small improvements can be predicted in insulation quality, these can be very significant economically because of the absolute magnitude of hydrogen losses in a hydrogen economy. More significant benefits are to be expected from improved insula- tion systems development. Standardizations of low heat flux measurements and the availabi- lity of standard reference materials would be beneficial in determining the most economic and effective insulating materials. The only effort related to the development of standard reference materials is that by Ludtke [116] to develop a series of low temperature transfer standards. Thermal conductivities of insulating materials are strongly dependent upon the compac- tion (density) of the insulating material, the type and pressure of the gas on the insulation space, and the reflectivity of the insulation surfaces. Howell [117] indicates that the principal problems with insulations are: hydrogen permeation of internal foam systems and cell breakdown for external foam systems, insulation and bonding integrity under the stresses induced by thermal cycling, and vacuum leaks with superinsulation and other evacuated insu- lation systems. Thus, the principle insulation requirements are systems design improvements and measurement standardization. 4.2.4 Oxygen Compatibility Regardless of the method used to produce hydrogen from water, oxygen is a by-product. Oxygen use has been growing at the rate of about 18% per year [118] (comparable to the growth of hydrogen production) and it is expected that this rate will persist or, more probably, increase. Mrochek [118] indicates a potential oxygen credit of 4$/ton of oxygen, but this is highly uncertain unless applications requiring huge amounts of oxygen are PAGENO="1267" 1261 (a) Unevacuated 0.001 0.01 0.1 Relative Thickness/unit heat loss 1.0 Foams, Fiber-glass, and Powders Evacuated Multilayer Foams, Fiber-glass, and Powders Multilayer Foams, Fiber-glass, and Powders Multilayer (b) Unevacuated Evacuated 0.01 0.1 1.0 Relative Weight/unit heat loss (c) Unevacuated Evacuated I- -I I I I 0.1 1.0 10 100 1000 THERMAL CONDUCTIVITY, pW/cm*K Figure 4.5 Comparative data for selected insulations. PAGENO="1268" 1262 developed. If this oxygen can be used we are faced with oxygen containment problems. Oxygen compatibility problems have been encountered in the space program and can be severe. The principal problem area is associated with the combustion (rapid oxidation) of the con- tainment scructural materials. It has been found that almost any material will burn in the presence of pure oxygen, especially at high pressures. This includes not only the common combustible materials but also metals and most other structural materials. A recent sur- vey on the subject is cited [119]. This review confirms that the problems are significant, must be given serious attention in any high pressure or high temperature application, and cannot be ignored even at ambient conditions. The oxygen compatibility of metals and polymers has been investigated most extensively. Few polymers are compatible with high pressure oxygen. Metals are generally much more compatible, but the degree of combustibi- lity varies widely from metal-to-metal. The degree of oxygen compatibility of ceramics is not extensively studied, but it is expected to vary widely according to the chemical composition of the ceramic. Oxide ceramics, for example, should be the most compatible and better than most metals. 4.3 MATERIALS REQUIREMENTS FOR HYDROGEN PRODUCTION The primary sources of hydrogen gas production have been the steam reformation of natural gas, the petrochemical industry [120-122] and more recently from water by electro- lysis [3,118,123]. As our dwindling fossil fuels are reserved for more essential purposes, more hydrogen will be obtained from water. Electrolysis of water requires an amount of electrical energy comparable to the energy stored in the hydrogen fuel produced. Thus, an immense electrical economy based on non-fossil fuels will need to be developed. This, in all probability, will be based on nuclear or solar power. Therefore, the materials requirements for the production of hydrogen fuel are closely linked with those of non-fossil fuel power generation as well. First, we direct our attention to the material requirements f or the generation of hydrogen by electrolysis and other water decomposition processes. 4.3.1 Electrolysis Water electrolyzer technology has developed to yield efficiencies of about 60% for large scale plants [4,11]. Gregory [2] points out that the maximum theoretical efficiency, based on electrical input energy, is 120%. The additional 20% comes from the thermal energy input to the electrolyzer. Since present efficiencies are only about 60%, it is reasonable to assume that sizeable gains in efficiency will occur with improved designs and materials. Efficiencies can be increased with the development of better electrode materials and configurations, to lower the overvoltage and internal resistance losses of the cells, and by operating the cells at higher temperatures and pressures. Kincaide [124] indicates an increase in efficiency of 15% is possible by operating at 700cc. It is noted that such increases in efficiency generally are accompanied by increased capital equipment costs. The structural material corrosion resistance requirements at increased temperatures will present a formidable materials development challenge. On the huge scale of production involved in a hydrogen economy, a few percent increase in efficiency represents billions of dollars in production cost savings per year in the U.S. alone. Gregory [2] indicates that General Electric and Westinghouse are developing units for operation near 2000cF. Teledyne Isotopes is developing a high temperature unit for operation PAGENO="1269" 1263 at a pressure of 3000 psi. Each of these involve materials corrosion and embrittlement problems because of the high temperatures and pressures. Electrolyzers are generally built in modular form [2,124] and could be scaled-up readily to the plant size required at a nuclear power plant site without addItional materials problems. The largest electrolyzer plants now operating are about one-tenth as large as will be required. The main materials requirements for electrolyzers are those affecting cost and longevity. 4.3.2 Thermochemical Water can also be decomposed by thermochemical decomposition. Thermochemical decom- position is appealing since thermal energy can be utilized directly without first generating electrical energy, a thermodynamically inefficient conversion at present. The production of significant proportions of hydrogen by direct thermal decomposition requires a temperature of about 2500CC [11] and is generally considered as impractical and inefficient with existing heat sources. Significant effort is being devoted to the development of efficient, lower temperature, thermochemical decomposition processes [11,125-128]. These processes are composed of multi- step chemical reactions from water to hydrogen at temperatures below l000~C [8,124,126]. The proposed chemical reactions involve highly corrosive chemicals, such as high temperature hydrobromic acid, further compounding the materials problem. Since the number of potentially useful processes is essentially limitless, no specific material requirements can be specified until a particular process is adopted. It is likely that structural material requirements related to thermochemical hydrogen production will include high-temperature strength, corro- sion resistance, and rqlative immunity to hydrogen embrittlement. Potentially useful ma- terials are noble metals, graphite, and ceramics, such as aluminum oxide [129,130]. 4.3.3 Other Production Methods Steam reforming of hydrocarbons is a common method of hydrogen production. The materials requirements for the extensively used method are well understood. Common struc- tural steels find wide application in the petrochemical industry in spite of existing serious hydrogen-related materials problems [68]. Bockris [125] and Maugh [11] describe more exotic methods of hydrogen production. For example, the very high temperatures of a fusion reactor could be utilized to generate photons with the correct energy to decompose water. Because of the highly speculative nature of those techniques and the enormous basic developments which must precede their application, it does not seem prudent to speculate on potential material requirements. 4.3.4 Hydrogen Liquefaction and Solidification Because of the low density of hydrogen gas, many volume-limited applications,, such as ground and air vehicles, are not well suited to the use of hydrogen gas. Also, cross- country gaseous hydrogen transfer by truck or stationary hydrogen gas storage is impractical. Therefore, hydrogen is often liquefied or solidified to increase its density for more com- pact storage. Liquid or slush (mixture of liquid and solid particles) hydrogen is considered to be the most viable option for use in aircraft [6,92,131,132] and as a somewhat less PAGENO="1270" 1264 attractive option for ground vehicles [11,133]. If these applications develop, a sizeable proportion (25%) of the total hydrogen usage will be in the form of liquid or solid. This liquefaction capability will dwarf present facilities [133]. Bartlit, et al. [133] indicate that the largest existing hydrogen liquefaction facility has a capacity of 60 tons/day. They feel that considerably larger plants can be built with no additional technology development. Daniels [13] has indicated that a material problem with turbine blade tips may develop in large scale turbine expanders. Excessive blade erosion due to droplet impingement nay result. 4.4 MATERIAL REQUIREMENTS FOR HYDROGEN TRANSFER AND STORAGE Hydrogen produced at the power plant, possibly several miles at sea, must be transported to the user site. Because usage rate fluctuates widely, large storage facilities will be required for the storage of gaseous, liquid, or solid hydrogen. Hydrogen in gaseous, liquid, or slush form can be transported by pipeline or mobile tanks. Considerable experience has been gained in the space program on the transfer and storage of liquid hydrogen [ 42,73,74, 91,112,134-139]. This experience shows that hydrogen in large quantities can be handled safely with no serious materials problems. 4.4.1 Gaseous Hydrogen The principal problems to be expected in the transfer and storage of gaseous hydrogen at ambient or high temperature are embrittlement and leakage. Embrittlement is most significant at high pressures and ambient temperature and is also significantly influenced by the purity of the hydrogen. Relatively impure gaseous hydrogen has been handled for commercial and industrial applications for many years [2-5,8,133] with no serious material failures. Based on recent experimental results, this is partly because the hydrogen transferred is not of the extremely high purity used in the space program and in laboratory research. "Town gas" or "manufactured gas" used during the past decades in the United States and still being used abroad is approximately 50% hydrogen. Basilea, Italy distributes a gas containing 80% hydrogen for domestic use [133]. Gregory [2] and Daniels [13] indicate that Germany operates several hundred kilometers of hydrogen pipeline at a pressure of 200 to 700 psi. No special safety features beyond those for other flammable gases are used. The pipe is seamless steel St.35.29 grade, similar to SAl 1015. Other shorter hydrogen gas pipelines are in service such as the 8 inch diameter, 12 mile long pipeline, operated at 200 psi by Air Products and Chemical, Inc. in Houston. No booster compressors are found along any of the pipelines because of their relatively short lengths. Extensive storage experience also exists through the commercial use of hydrogen cylinders operated to above 2000 psi. These are hot-forged monolithic carbon steel cylinders; it is likely that the lack of hydrogen related incidents is due to the lack of severe metallurgical variations such as those produced in a weld zone. PAGENO="1271" .1265 Research has been conducted for several years at Battelle Memorial Institute 1140] to determine the effects of cathodic hydrogen-charging on pipeline materials. Steels with 61 ksi to 181 ksi yield strengths were tested under laboratory conditions. They concluded that pipeline steel materials with yield strengths below 130 ksi would present no problems under the usual ground water conditions. Groenveld, et al. 1140] also performed field studies of up to 8 years with buried sections of pipe. Their field results are consistent with the laboratory results. This is a study of internal hydrogen embrittlement. Based on the results of Chandler [60].on hydrogen environment embrittlement similar field tests for hydrogen-environment embrittlement should also be conducted on pipeline materials. Although hydrogen transfer and storage systems are envisioned to be relatively low pressure (below 2000 psi), the storage pressures of hydrogen gas, in some instances, is much higher. And, in addition, the purity of the hydrogen can be very high. Both of these factors contribute significantly to the embrittlement problem. Several instances have been cited of failures of high pressure gaseous hydrogen storage tanks and gauges [41, 42,48,53,141,142]. Fortunately, none of these failures attained their full potential destructiveness, and loss of life and property damage has been relatively small. In many of these high pressure failures, material fracture has occurred far below design strength. Embrittlement is the most serious material problem in a hydrogen economy and should receive considerable support for materials development and a more thorough understanding of hydrogen-environment embrittlement phenomena. Studies should be conducted on well-charac- terized research materials under controlled laboratory conditions and on specimens ob- tained from production run material; tests under actual field conditions. Embrittlement of hard spots and welds, including the heat affected zone, has been especially troublesome and must be closely scrutinized. Gaseous hydrogen-environment embrittlement has been researched primarily in connection with the NASA space program [41,50,51,53,54] but con- siderable work remains to obtain a complete understanding of the mechanisms involved, to be able to develop more immune materials, and to obtain design data for existing materials. Plastic pipelines for hydrogen transfer should be researched to determine if any degradation occurs and which materials are most compatible, especially from the standpoint of permeability. Another area which should be investigated is the effect of additives, such as odorants, to gaseous hydrogen. Additives may either enhance or inhibit crack growth of containment materials. 4.4.2 Liquid and Frozen Hydrogen Commercial and government liquid and slush hydrogen handling experience has been primarily in conjunction with the NASA space effort and related research [73,74,76,112,120, 133-135,143]. The main research efforts in the space program have been directed toward pump, transfer line, storage vessel, and insulation development [77,78,91,134,138,139, 144-146]. Long distance transport of liquid hydrogen is now routinely accomplished with trucks (13,000 gallon capacity) and railroad tankers (28,000 gallon capacity). Because of the low density of liquid hydrogen (71 grams/liter) these vehicles are limited by volume, not weight. Boil-off losses of 1/4 percent per day are typical and for larger vessels the PAGENO="1272" 1266 losses can be maintained at smaller levels. Over shorter distances (a few thousand feet), vacuum jacketed transfer lines of inside diameters up to 20 inches and pressures up to 2000 psi are in use [133]. Bartlit [133] also points out that reciprocating, centrifugal, and axial flow pumps for a wide range of pumping volumes have been developed. At the Nuclear Rocket Development Station in Nevada, for example, liquid hydrogen has been pumped at rates up to 35,000 gallons/minute. Based primarily on NASA experience, the principal technological material problems with liquid and slush hydrogen transfer have been with pump bearings and seals, and economic insulation techniques [92,142,144,146-150]. Because of the lack of extensive experience, pump wear problems for continuous long term slush hydrogen transfer are not definitive. Storage vessels exceeding 500,000 gallons of liquid hydrogen are in use with boil-off rates on the order of 0.05Z/day. This is equivalent to a hold time of over five years. The largest dewar built has a capacity of 900,000 gallons and Bartlit [133] indicates that no further materials development is needed to go to four or five million gallon capacity, which approaches the volume required for the needs of a hydrogen economy. The current cost of such vessels is about $2.00 per gallon capacity. It is likely that liquid hydrogen will. be a strong contender in transportation applications. A liquid hydrogen storage vessel for automotive use has been developed [133). It is estimated that on a mass production basis these will cost from 300 to $600. Research to develop lower cost structural materials, in- sulations, and fabrication techniques (such as the development of filament wound composite vessels) could result in substantial economic savings. If hydrogen is generated at sea-based plants it must be transported to land for use. Large liquid hydrogen tanker ships or barges [1511 similar to the liquid natural gas ships now in use [152], may be the most attractive form of transfer. The insulation requirements for a liquid hydrogen tanker will be nore severe because of the lower boiling temperature; however, the weight requirements (structural strength) will be reduced because of the lover density of liquid hydrogen. Several million pounds of steel are used in the liquid con- tainers of a large LNG tanker and huge quantities of insulation are also required. Similarly large quantities of steel and insulation are required for stationary storage vessels. The reduction in capital cost, through a few percent reduction in material costs because of new materials development, is an obvious benefit. The economics of piping liquid versus alternate methods of delivering liquid hydrogen are examined in Chapter 6. Liquid hydrogen transfer through pipelines may be more economi- cally feasible if it is combined with the transfer of electrical energy, via a low resistance or a superconducting transmission line [153,154]. Another combination is the transfer of liquid hydrogen, liquid natural gas, and electric power [133]. Novak [155] discusses a potential problem of cooldown flowrate limits imposed by thermal stresses. No technological material breakthroughs are required in these proposed applications, but improved low cost insulations, structural materials, and fabrication procedures may help to provide an econo- mically competitive system. PAGENO="1273" 1267 4.4.3 Hydride Storage Hydrogen can also be stored by chemically combining it with various metals as a hydride. With the application of heat the hydride is dissociated and hydrogen gas is re- leased for use. Hydrogen densities larger than liquid hydrogen densities can be obtained by this method and, therefore, it is of strong current interest [ 156-160]. The main drawback at the present time, for mobile applications, is the very high overall weight and volume of such systems. Further research is warranted for the development of light- weight, inexpensive materials which absorb large quantities of hydrogen and readily liberate hydrogen at near-ambient temperatures and pressures. The concept of hydride storage systems is especially appealing for stationary applications. 4.5 MATERIALS REQUIREMENTS FOR HYDROGEN APPLICATIONS The mast prominent uses of hydrogen at present are in the petrochemical industry and in the production of methanol and ammonia [121]. Hydrogen is also used in rocket propul- sion and in commercial hydrogenation. The experience gained through the space program has been monumental and the amount of liquid hydrogen used has dwarfed any other past applica- tions [133,143]. Hydrogen has been used both in gaseous and liquid forms and prdliminary research has been performed on the use of hydrogen in slush form because of its higher density [137,139,146,161-164]. Liquid and slush hydrogen are especially appealing for use in aircraft and space vehicles. In a hydrogen economy the emphasis in applications would change such that the major portion of hydrogen would be used for space heating, commercial and domestic propulsion systems, and the generation of electric power; that is, almost anywhere that fuel oil, kerosene, gasoline, and natural gas are used today. The following sections discuss the materials requirements imposed by the use of hydrogen for such applications. Because the limitations of hydrogen-material compatibility are not yet well understood, considerable effort must be directed toward equipment, material, and regulatory developments before a hydrogen-economy can be realized. 4.5.1 Heating Hydrogen can be used for heating with some modifications in existing heating systems. Space heating with hydrogen is appealing because of the potential of reducing flue heating losses and a resultant gain in heating efficiency. The compatibility of materials in existing systems has not%een studied. The advantages of using hydrogen for space heating can best be realized with concept- ually new heating devices [165]. These devices would be based on flameless catalytic con- version of hydrogen and oxygen to water. Through the use of various catalysts one can achieve a wide range of combustion temperatures, ranging from temperatures in the cryogenic range to 3O00~C. Thus one can visualize a wall radiator heating a room by catalytically combusting hydrogen in the wall at a temperature of 80~F or a burner on a stove operating at 2l2*F, etc. Most of the past work has centered on classical catalytic materials such as platinum and nickel but recent interest in the catalysis of the H2 - 02 reaction has brought other materials under investigation [166-174]. Some of the materials being studied are silicon carbide, thorium, platinum, nickel, silver, transition metal carbides, and copper. PAGENO="1274" 1268 The potential catalyst market in domestic applications is large and warrants sizeable materials research. Studies should be directed toward the development of economic catalytic materials for applications over wide temperature ranges. 4.5.2 Propulsion The application of hydrogen fuel to propulsion, including automobiles, buses, trucks, boats, small ships, aircraft, and spacecraft, represents a major undertaking. However, the technical feasibility of converting conventional engines, both reciprocating and rotary, has been demonstrated [10,131,132,175-181). These conversions include a railroad engine which operates on hydrogen fuel [182], but railroads are equally adaptable to electrical power. Large ships may be better propelled by nuclear power, except in special instances, such as fuel tankers where boil-off or part of the fuel load itself can be used for energy. Experience with hydrogen operated engines is still limited, but it appears that problems will be minor except in high pressure (above 2000 psi) applications. .Jewett, et al. [41] feel that many hydrogen-related materials problems will arise in the development of hydrogen fueled engines. They strongly recommend doing tests on components for hydrogen service equipment under operating conditions. Friek, et al. [65] have observed high temperature embrittlement on Udimet; water had no inhibiting affect. Udimet is a space shuttle main engine alloy. Quandt [183] is planning further research on hydrogen fueled gas turbines. The principal concern in this area is again related to embrittlement phenomena. Bartlit [1841 has indicated the LASL is undertaking an extensive project to convert an automobile to hydrogen fuel and to build a prototype refueling station. A liquid hydrogen tank for the vehicle is being built and impact tests are planned to test the material integrity. They feel the structural integrity should be sufficient to withstand impacts which an occupant 4.5.3 Electric Power Generation Hydrogen~wil1 also find application for domestic and commercial electric power genera- tion through the use of fuel cells and hydrogen fueled engines. The present efficiency of large fuel cells is about 60% and the maximum efficiency is 83.5% at 25'C [2,166]. Thus considerable improvement is possible through the development of more effective electrode materials, higher operational temperatures and pressures, and more efficient design. Simi- lar to the existing situation for electrolyzers, a small percentage increase in efficiency can amount to millions of dollars in energy and cost savings. Austin [1661 performed an extensive survey of government sponsored research on fuel cells and this work is also an excellent sourcebook of information on the state-of-the-art and the principles of operation of fuel cells. Included in this work is a section on materials compatibility, listing many structural materials and their usefulness with various fuel cell chemicals. Some advances have been made since this review, but currently realized efficiencies suggest that his recommendations are still valid. He recommends research to improve the efficiency of fuel cells through the development of more effective electrodes and electrolytes. He also recommends research directed toward the reduction of the amount of expensive catalytic materials required, often platinum, and the development of less ex- pensive catalysts. It has been indicated that the thickness of catalytic coatings has reached PAGENO="1275" 1269 a lower limit (1 mg/cm2) [13] thus necessitating cheaper materials for further cost re- duction. Another area which requires attention is the effect of additives or impurities in hydrogen on catalytic materials. Poisoning of catalytic materials can seriously shorten the life of these materials. A more complete and recent review of fuel cell technology is presented by Berger [166a]. Fuel cell power capacities have increased into the kilowatt range, which are adequate for many domestic and industrial applications. Units with capacities in the megawatt range are currently under development. Such units wIll be used for electric power generation. The application of hydrogen fueled engines to generate electric power has been described [144,176,177]. The materials requirements with these engines are the same as those described in the propulsion section. In summary, materials requirements are dictated by higher temperature and pressure operations of fuel cells; improved, lower-cost catalytic materials; and, again, structural materials resistant to corrosion and embrittlement. 4.6 RECOMMENDATIONS As indicated earlier, it is difficult to recommend specific research in a given area until existing data is critically evaluated and applications are well defined. Such a situation does not totally exist for the requirements of a hydrogen economy; however, based on the previously mentioned recent reviews on various phases of this subject, the following are recommended. 4.6.1 Structural Materials Research (1) Perform on a continuing basis: compilations, reviews, critical analyses and evaluations, and select best materials on the basis of physical properties data and compatibility. (2) Perform embrittlement studies over a wide range of applicable conditions on materials selected as a result of (1) to: (a) obtain a better understanding of embrittle- cent mechanisms, (b) determine how embrittlement depends on microstructure, temperature and pressure, stress, strain rate, composition and other pertinent parameters, (c) deter- mine effective inhibiting additives and protective coatings, and (d) develop reliable and reproducible test methods for embrittlesent characterization. Develop non-destructive test methods and life prediction techniques to detect or avoid incipient failure of structural material. Acoustic, eddy current decay, and other NDT techniques should be studied for application. Research should also be directed toward an evaluation of existing and new theories [186-190] of embrittlement. (3) Perform mechanical and thermal properties measurements, especially at low tem- peratures, on existing materials lacking in characterization and on new materials, especially metals and composites and also polymers, ceramics and insulations. (4) Develop new light-weight, high-strength materials for fabrication of vessels and transfer lines. Examine the applicability of composite materials (e.g., filament wound vessels) to domestic equipment. Direct research toward the development of low-cost, mobile vessels for application to automobiles, aircraft, and ocean tankers. PAGENO="1276" 1270 (5) Consideration should be given to novel designs, for maximum use of unique material properties and minimization of the developing material scarcity problem. 4.6.2 Insulation Research (1) Improve standardization of low heat-flux measurement systems and develop standard reference materials to improve reliability of measurements and facilitate accurate intercomparisons. (2) Perform research on existing and new insulation materials directed toward the development of lower cost insulations and more effective system designs to minimize heat losses, especially at thermal bridges. 4.6.3 Catalytic Material Research Perform research on existing and new catalytic materials to obtain lower-cost, more efficient materials. Research should optimize the quantity of material required in a catalytic device and recovery systems should be studied for material conservation. The effect of hydrogen gas impurities and additives on the efficiency and life expectancy of catalytic materials should be studied. Methods of reactivating poisoned catalysts should be investigated. 4.7 ACKNOWLEDGMENTS I wish to express my appreciation to members of the Cryogenics Division for their assistance in the technical aspects of this review, especially Jesse Hord, Richard P. Reed, and Richard H. Kropschot. I also wish to thank those outside of the division who generously supplied information contained in the report, in particular, Neville Daniels, William Chandler, T. P. Groeneveld, and A. R. Troiano, among many others too numerous to mention. In addition, Ken Kozik's selfless assistance in retrieving and filing documents is grate- fully acknowledged. PAGENO="1277" 1271 4.8 REFERENCES 1] Hord, J., Cryogenic 112 and National Energy Needs, Book, Advances in Cryogenic Engineering 19, (Ed.) K. D. Timmerhaus, p. 1-11 (Plenum Press Inc., New York, N.Y., 1974). [2] Gregory, D. 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T., The High Pressure H2-02 Fuel Cell, Ind. Eng. Chem. 52 p. 301-303 (Apr. 1960). [168] Jennings, T. J., Voge, H. H., and Armstrong, W. E., Catalysts for Initiating the Hydrogen-Oxygen Reaction at 78'K, J. Cata?. 24, Ho. 3 p. 493-501 (Mar. 1972). [169] Jennings, T. J., Armstrong, W. E., and Voge, H. H., Development of Hydrogen-Oxygen Catalysts, Shell Development Co., Emeryville, Calif., Final Report NASA-CR-72?18 (Jul. 1966). [170] Ladacki, M., Mouser, T. 3., and Roberts, R. W., Catalyzed Low-Temperature Hydrogen- Oxygen Reaction, J. Catalysts 4, No. 2 p. 239-247 (1965). [171] Lee, W. B., Feasibility Study of Oxygen/Hydrogen Powdered Metal Ignition, Final Report (Sept. 16, 1964), Marquardt Corp., Van Nuys, Calif., Rept. N67-3l967/HASACR- 68773. [172] Roberts, R. W., Burge, H. L., and Ladacki, M., Investigation of Catalytic Ignition of Oxygen/Hydrogen Systems, Rocketdyne, Canoga Park, Calif., Rept. NASA-CR-54657 (Dec. 1965). [173] Lee, H. B., Cryogenic Ignition of Hydrogen and Oxygen with Raney Nickel, md. Eng. Chem., Prod. Res. Develop. 6, No. 1 p. 59-64 (1967). [174] Laramore, G. E., Houston, T. E., and Park, R. 1., Catalytic Combustion of Hydrogen, Proc. of THEME Conf, Univ. of Miami, Fla., (Mar. 1974). [175] Arp, V. D., Clark, A. F., and Flynn, T. M., Some Applications of Cryogenics to High Speed Ground Transportation, Nat. Bur. Stand. (U.S.), Tech. Note 635 (Feb. 1973). 4 [176] Beremand, D. G., Joyce, J. P., and Cameron, H. H., An H2-O2 Auxiliary Power Unit for Space Shuttle, NASA-Lewis Tech. Memo. TMX-68084 Proc. of 7th IECEC (Sept. 1972). [177] Mulready, R. C., Liquid Hydrogen Engines - Chapter 5, Book, Technology and Uses of Liquid )[y4, (Ed.) R. B. Scott, W. H. Denton, and C. M. Nicholls, p. 149 (Macmillan and Co., New York, 1964). [178] Chopey, N. P., Hydrogen: Tomorrow's Fuel?, Chem. Eng. p. 24-26 (Dec. 25, 1972). [179] Weil, K. H., The Hydrogen I. C. Engine - Its Origins and Future in the Emerging Energy_Transportation-Environment System, Paper #729212 - Proc. of the 7th IECEC, 1355-1363 (1972). [180] Morgan, N. E., and Morath, W. D., Development of a Hydrogen-Oxygen Internal Combustion Engine Space Power System, NASA-CR-255 (1965). PAGENO="1287" 1281 [181] Anschutz, R. H., Hydrogen Burning Engine Experience, NASA Working Symposium on Liquid Hydrogen Fueled Aircraft p. 127-150 (May 15-16, 1973). [1821 Ordin, P., NASA, Cleveland, Ohio, Private Communication. [183] Quandt, E,, NSR&DC, Anapolis, Md., Private Communication. [184] Bartlit, J. R., LASL, New Mexico, Private Communication. [185] Carroll, W., NBS, Washington, D.C. Private Communication. [186] Beachem, C. D., A New Model for Hydrogen-Assisted Cracking (Hydrogen `Embrittlement'), Metallurgical Transactions 3, p. 437-451 (Feb. 1972). 187] Oriani, R. A., A Mechanistic Theory of Hydrogen Embrittlement of Steels, U.S. Steel Corp., Monroe, Pa. (Dec. 1971). I 188] Troiano, A. R., and Fidelle, J. P., Hydrogen Embrittlement in Stress Corrosion Cracking, Hydrogen in Metals Conf., Paris, France (May 1972). [189] Troiano, A. R., Role of Hydrogen and Other Interstitials in the Mechanical Behavior of Metals, Trans. Amer. Soc. Metals 52 (1960). 190] Troiano, A. R., Embrittlement by Hydrogen and Other Interstitials, Metal Progresa p. 112-117 (Feb. 1960). PAGENO="1288" 1282 4.9 APPENDIX LIST OF RECENT AND ON-GOING HYDROGEN RELATED MATERIAL RESEARCH Material research directed toward hydrogen applications is abundant. A listing of the recent and current research is desirable to plan future research. The literature collected for this investigation contains information regarding recent efforts. In order to obtain a more complete listing, the following files were also searched for hydrogen related materials research: Smithsonian Scientific Information Exchange, An Inventory of Energy Research by Oak Ridge National Laboratory, and the NASA Research and Technology Operating Plan. The more pertinent of these efforts are listed in that which follows. A listing of facilities, at which hydrogen related materials research has been recently con- ducted, is also included. The principal fields of interest are indicated. Because of the large number of investigations which pertain in some manner to the applications of hydrogen and oxygen, some significant omissions exist. For these unintentional omissions, the author apologizes. 4.9.1 Material Development Projects Title: Thermodynamic and Other Studies of Metal/Hydrogen Systems Contact: K. A. Moon Institution: U.S. Amy, Materials & Mechanics Research Center, Watertown, Boston, Massachusetts 02172 Summary: To obtain thermodynamic data for metal/hydrogen systems and to interpret the data in terms of interactions within the solids. Improved materials or material may result via: (1) Obtaining data directly applicable to materials design problems involving Ti, Zr, V, Nb, or Ta. (2) Improved understanding of interstitial solutes, H, B, C, N, and 0, which pro- foundly affect strength, brittleness, and aging of metals. (3) Cooperation with other AMXRC investigators on more applied R&D involving joining or sintering techniques which employ metal hydrides. Title: Composites Contact: J. C. Freche Institution: Lewis Research Center Summary: The overall objective of this research is to develop fiber and laminate composite materials, structures, and components for various aeronautical applications. Temperature levels of interest range from cryogenic temperatures to over 250'F. The major objectives for the programs are as follows: (1) To develop or synthesize improved polymers suitable for use as matrix materials for temperatures up to 6OO~F. (2) To improve such properties of polymer matrices as thermo-oxidative stability, shear strength (in association with fibers) and toughness. (3) To develop carbon and boron fiber-polymer matrix composites with greater strengths, moduli, fiber matrix bonds and toughness. Title: Interdisciplinary Laboratories for Materials Research Contact: R. A. Lad Institution: U.S. National Aeronautics and Space Administration, Lewis Research Center, Cleveland, Ohio Summary: The objectives are to: (1) Obtain new understanding of the relationships between electronic, atomic, molecular and microscopic structures of solids and their useful mechan- ical, structural, electronic and chemical properties; (2) Employ the expertise existent in universities to obtain knowledge in these areas and to aid in determining the best direc- tions to follow in improving existing materials and obtaining new materials of direct inter- est to NASA programs. Research topics include interatomic forces in solids, corrosion, diffusion, polymer rheology, composites, computer memory materials, hydrogen embrittlement, superconductivity, grain boundary mobility in ceramics, solid electrolytes, dispersion strengthening, electromigration, spacecraft coating materials, crystal growth, computer memory materials and others. PAGENO="1289" 1283 Title: Improved Performance Metallic Materials Contact: H. Kato institution: U.S. Department of the Interior, Bureau of Mines, Albany, Oregon 97321 Summary: The objective is to develop metallic materials of construction specifically as follows: (1) Resistant to hydrogen embrittlement as encountered in pipeline steels con- tacting sour natural gas and oil. (2) Resistant to hydrogen fluoride-phosphoric acid media which may be abrasive aqueous liquids or humid vapors at temperatures to 2OO~C. (3) Re- sistant to chlorine and chlorine containing sulfur at temperatures to 650'C. Title: High Strength Materials Contact: V. F. Zackay institution: University of California, Lawrence Berkeley Laboratory, Berkeley, California 94720 Summary: Relationships between chemistry, microstructure and mechanical properties are being developed to allow design of materials with superior combinations of strength, ductility and toughness. The effects of lowering the stacking-fault energy (thereby pro- ducing various mixtures of austenite (gamma) and bcc (alpha) or hcp (epsilon) martensite) will be further studied with respect to mechanical properties and susceptibility to hydrogen embrittlement. Further corrosion, stress-corrosion cracking, hydrogen embrittlement and corrosion fatigue evaluations of several metastable austenites will be made to allow delinea- tion of proposed fracture mechanisms. Accurate measurements of secondary incubation times for the thermally-activated process will be made as a function of stress intensity level and test temperature so that a mechanical-environmental analysis will be possible. Other active facilities: 1. Institute of Gas Technology 4. Oak Ridge National Laboratory Chicago, Illinois Oak Ridge, Tennessee Contact: 0. P. Gregory Contact: J. E. Mrochek 2. Naval Research Laboratory 5. Sandia Laboratories Washington, D.C. Livermore, California Contact: C. 0. Beachem Contact: J. H. Swisher 3. North Carolina State University Raleigh, North Carolina Contact: R. B. Benson, Jr. 4.9.2 Hydrogen-Environment Embrittlement Projects Title: Materials Environmental Compatibility for Space Shuttle Cnntact: C. E. Cataldo Institution: U.S. National Aeronautics & Space Administration, Marshall Space Flight Center, Huntsville, Alabama 35812 Summary: The objective of this study is to determine the effects of various environments anticipated during fabrication, storage, and flight of the shuttle on structural materials, both with respect to short term effects and long life effects. The studies covered under this RTOP include the effects of high pressure gaseous hydrogen on materials, flammability characteristics of materials in oxygen, corrosion susceptibility and outgassing character- istics of non-metallic materials. Title: Fatigue, Fracture, and Life Prediction Contact: G. Goodwin Institution: U.S. National Aeronautics & Space Administration, Ames Research Center, Moffett Field, California 94035 Summary: The deleterious effects of stress corrosion on the mechanical properties of aircraft and spacecraft structural metals are being studied in order to develop analytical techniques and physical test criteria for predicting and minimizing such effects. In par- ticular, an understanding of the embrittlement of metals by gaseous hydrogen will be sought. PAGENO="1290" 1284 4.9.3 Internal Embrittlement Projects Title: Effect of Hydrogen on the Mechanical Properties of Titanium and Titanium Alloys for Use in Naval Aircraft Contact: E. S. Tankins Institution: U.S. Navy, Air Vehicle Technology Department, Warminster, Pennsylvania 18974 Summary: To study the effects of hydrogen absorbed at low temperatures on the embrittlement of various titanium alloys used in naval aircraft. Title: Use of Nuclear Techniques to Study Naval Aircraft Materials and Processes Contact: D. A. Lutz Institution: U.S. Navy, Air Vehicle Technology Department, Warminster, Pennsylvania 18974 Summary: Fundamental studies of hydrogen embrittlement during chromium plating, of gas absorption by high temperature alloys. Title: Electrochemical and Metallurgical Aspects of Environmental Stress Cracking of Alloys Used in Naval Aircraft Structures Contact: J. J. Deluccia Institution: U. S. Navy, Air Vehicle Technology Department, Warminster, Pennsylvania 18974 Summary: The phenomena of stress corrosion and hydrogen embrittlement of naval aircraft alloys in the simulated air-sea marine environment are being studied from a mechanistic standpoint. Title: Stress Corrosion and Hydrogen Embrittlement Characteristics of Missile Structural Materials Contact: J. T. Davidson Institution: U.S. Army, Ground Support Equipment Laboratory, Redstone Arsenal, Huntsville, Alabama 35809 Summary: To generate data on the susceptibility of precipitation hardening (PH) type stainless steel alloys to stress-corrosion failure. Of major interest will be those PH type alloys currently being utilized in Army missile systems as LA2~CE, DRAGON and TOW. Title: Mechanism of Stress Corrosion Cracking 2841 Contact: H. H. Uhlig Institution: Massachusetts Institute of Technology, School of Engineering, Cambridge, Massachusetts 02139 Summary: To study the nature of the metal-ion interaction and the function of the tensile stress involved in cracking. This project is concerned with the mechanisms involved in stress corrosion cracking. To determine whether cracks generated in mild steel or austenitic stainless by stress-corrosion are initiated and grow by local electrochemical action or whether a crack grows because the surface energy is reduced by the chemisorption of specific ions. To differentiate between stress-corrosion cracking and cracking by hydrogen embrittle- ment, and to clarify the role of interstitial impurities in the behavior toward hydrogen cx- hibited by vacuum-melted, cold-worked alloys of iron with metals such as nickel, cobalt, aluminum, or manganese. Title: Navy Vehicle Design and Construction: Mechanisms of Hydrogen Embrittlemeat in Metals and Alloys Used in Naval Structures Contact: H. K. Birnbaum Institution University of Illinois, School of Engineering, Urbana, Illinois 61801 Summary: This research undertakes to clarify the mechanisms by which hydrogen can embrittle metals and alloys, such as those used for Naval aircraft and ship structures. The investi- gators are to study crack initiation and propagation in niobium-hydrogen and iron-hydrogen alloys. Temperatures and hydrogen content are to be varied so that cracking may be studied in alloys both with and without the presence of precipitated hydrides. Acoustic emission techniques are to be used to follow crack growth and deuterium will be used as a substi- tute for hydrogen in certain cases to check diffusion constants and rates. Also, oxygen doping (which alters the diffusion rate of hydrogen in niobium) will be used to determine the effect of hydrogen diffusion rate on crack growth. PAGENO="1291" 1285 fitle: Navy Vehicle Design and Construction: Investigation and Application of Strengthening Methods to Titanium Alloys Contact: A. W. Sommer Lnstitution: Rockwell International Corporation. International Airport, Los Angeles, California 90009 ummary: This research project is aimed at providing needed strength improvements in titanium and its alloys. The mechanical properties will be determined to obtain the structure-property relationships. The interaction of hydrogen with dislocations in alpha titanium will be followed by internal friction measurements. itle: Navy Vehicle Design and Construction: Mechanisms of Hydrogen Embrittlement in ietals and Alloys Used in Naval Structures Contact: L. Nanis Institution: University of Pennsylvania, School of Chemical Engineering, 203 Logan Hall, Philadelphia, Pennsylvania 19130 Summary: This research undertakes to clarify the mechanisms by which hydrogen can embrittle metals and high strength alloys, such as those used for Naval aircraft landing gear assemb- lies. Iron, nickel, and titanium base alloys are being given controlled hydrogen distribu- tions while under tensile stress. Hydrogen distribution and permeation rate is being corre- lated with stress-strain behavior and fracture characteristics using conventional metallur- gical techniques. Title: Navy Environment: Study of Hydrogen Embrittlement Mechanisms in High Strength Steels Contact: E. A. Steigerwald Institution: TRW Incorporated, Cleveland, Ohio 44117 Summary: The objective of this research is to define the mechanisms by which hydrogen can embrittle high strength steels such as those used in landing gear of Naval aircraft and rocket motor casings. The mechanical properties of various high strength steels with and without hydrogen are being determined as a function of temperature, heat treatment, strain rate, specimen geometry, and testing environment. The evaluation of the mechanical behavior of these materials along with x-ray line broadening studies and permeability studies are being used to determine hydrogen embrittlement mechanisms and the factors which control the embrittlement process. Title: Fundamental Corrosion Studies: Hydrogen Embrittlement Contact: L. Nanis Institution: University of Pennsylvania, Laboratory for Research on Structural Matter, 203 Logan Hall, Philadelphia, Pennsylvania 19104 Summary: To link stress and hydrogen distribution in the study of hydrogen embrittlement of steels by controlling of hydrogen distribution by electrochemical methods during actual mechanical testing. Tensile specimens of 4340 steel with controlled hydrogen distributions will be stressed to determine the interaction of hydrogen and microstructural features in embrittled material. Title: Environmental Sensitivity of Structural Metals - Liquid Metal Embrittlement Contact: P. Gordon Institution: Illinois Institute of Technology, School of Engineering, 3300 5. Federal Street, Chicago, Illinois 60616 Summary: This research is an extension of on-going research on liquid metal embrittlement to include the methodology of fracture mechanics. The areas to be investigated include: (1) The effect of prior deformation on the fracture behavior of metals. (2) The role of grain boundaries as the path for fracture propagation. (3) Experimental and theoretical studies of materials hysteresis. Title: Stress Corrosion and Hydrogen Embrittlement in Desalination Equipment Contact: Prof. A. R. Troiano Institution: Case Western Reserve University, School of Engineering, University Circle, Cleveland, Ohio 44106 Summary: This program examined the resistance to SCC and hydrogen embrittlement in saline * solutions of high strength aluminum base alloys, austenitic and martensitic stainless steels and mood. PAGENO="1292" 1286 Title: Investigation of the Effects of Hydrogen on the Structural-Mechanical Properties of a Titanium-2 Nickel Alloy Contact: R. E. Westerman Institution: Battelle Memorial Institute, P.O. Box 999, Richland, Washington 99352 Summary: Determine the effects of hydrogen on the tensile, fatigue crack growth, fracture, and acoustic emission behavior of 0.040 in. thick Ti-50A and Ti-2Ni strip. Title: Stress Corrosion and Hydrogen Embrittlement in Desalination Equipment - Environ- mentally Induced Brittle Delayed Failure Contact: Prof. A. R. Troiano Institution: Case Western Reserve University, School of Engineering, University Circle, Cleveland, Ohio 44106 Summary: This program explores the SCC of a variety of alloys exposed to saline solutions as related to a hydrogen embrittlement mechanism. Title: The Effect of Electrochemical Factors on the Stress-Corrosion Cracking of Titanium Contact: .1. F. Gloz Institution: Ohio State University, School of Engineering, 190 N. Oval Dr., 102 Administra- tion Bldg., Columbus, Ohio 43212 Summary: Current research is aimed at determining the amount and effect of hydrogen intro- duced into titanium under various electrochemical conditions. Also the effect of alloying additions on the hydrogen concentration is being examined. A new and relatively simple technique for determining low hydrogen concentrations in metals is being developed. Title: Hydrogen Embrittlement - Steel Contact: C. G. Interrante Institution: U.S. Department of Commerce, National Bureau of Standards, Washington, District of Columbia 20234 Summary: This new project is undertaken to establish limiting conditions in respect to strength levels, hydrogen content or effective hydrogen pressure, and temperature for the changeover from microcrack propagation fracture behavior to fracture by ductile rupture. Title: Hydrogen Embrittlement in Prestressing Steels Contact: D. Bailey Institution: University of Newcastle Upon Tyne, Newcastle Upon Tyne, England, United Kingdom Summary: The effects of composition, heat treatment, polarization potential, electroplating, and environmental conditions on the development of hydrogen embrittlement in prestressing steels is being studied. Title: Research on Corrosion and Inorganic Protective Coatings for Naval Aircraft Use Contact: S. J. Ketcham Institution: U.S. Navy, Air Vehicle Technology Department, Warminster, Pennsylvania 18974 Summary: Research into instrumental methods to detect hydrogen embrittlement with emphasis on design of a portable version of the permeation apparatus for in-situ measurements (so- called barnacle electrode); hydrogen permeation studies on steels and titanium alloys; characterization of corrosion behavior of composites, both metal fiber/metal matrices and metal fiber/organic matrices; research on coating systems to minimize corrosion and embrittle- mont; and study of mechanism of cadmium enbrittlement of high strength steels. Title: Analysis of the Ductile-Brittle Transaction Tem~erature in Fe-Binary Alloys Contact: W. H. Gerberich Institution: University of Minnesota, School of Engineering, Institute of Technology, Minneapolis, Minnesota 55414 Summary: A systematic study of both the flow and fracture characteristics of binary alloys of iron is proposed so that the following salient factors involved in the ductile-brittle transition temperature may be evaluated. (1) Atom size effect. (2) Metallic bonding effect. (3) Concentration dependence. (4) Dislocation dynamics as applied to both flow and fracture. In addition, several preliminary studies of dislocation and cracking mechan- isms as associated with slow crack growth processes are being carried out. One of these, associated with hydrogen embrittlement, promises to provide considerable insight into the stress gradient effects on hydrogen diffusion. PAGENO="1293" 1287 Title: Effect of Environment on Fracture Behavior Contact: H. H. Johnson institution: Cornell University, School of Engineering, 242 Carpenter Hall, Ithaca, New York 14850 Summary: A detailed characterization of hydrogen "trapping" in iron and steels is essential to an improved understanding of hydrogen brittleness and some stress corrosion phenomena. Particular experimental attention is directed to the temperature dependence of the trapping parameters. Identical strength levels will be obtained by two different pro- cessing routes, cold working and quenching and tempering. The first produces a micro- structure resistant to stress corrosion; the quenched and tempered microstructure is more susceptible. 4.9.4 Hydride Embrittlement Projects Title: Precipitation and Dispersion Hardening in Hexagonal Alloys Contact: Dr. H. S. Stoloff Institution: Rensselaer Polytechnic Institute, School of Engineering, 110 - 8th, Troy, New York 12181 Summary: This research has as its primary objective the study of the role of second phases in the plastic deformation and fracture of metals of hcp structure, Tests to determine whether hydride cracking during plastic deformation limits strength at high hydrogen levels will involve prestrain at 77 degrees K, followed by tests at 298 degrees K. The role of oxygen in supressing cross-slip in hafnium-hydrogen alloys also will be investigated. Title: Fatigue Behavior of 8CC Metals Contact: Prof. N. S. Stoloff Institution: Rensselaer Polytechnic Institute, School of Engineering, 110 - 8th, Troy, New York 12181 Summary: The objective of the proposed work is to determine the resistance of polycrystal- line high purity vanadium to cyclic deformation. The test program will eventually be extended to vanadium-hydrogen alloys. Other Active Facilities (all types of embrittlement) 1. Alcoa Laboratories Alcoa Center, Pennsylvania Contact: P. D. Hess 2. Atomic Energy of Canada Chalk River Nuclear Laboratory Chalk River, Ontario, Canada Contact: C. E. Ells 3. Atomic Energy of Canada Whiteshell Nuclear Research Establishment Pinava, Manitoba, Canada Contact: A. Sawatzky 4. Battelle Memorial Institute Columbus, Ohio Contact: T. P. Groeneveld 5. Bethlehem Steel Corporation Bethlehem, Pennsylvania Contact: H. E. Townsend 6. Boeing Company Seattle, Washington Contact: R. G. Bassett PAGENO="1294" 1288 7. Bro~-Boveri Baden, Switzerland Contact: M. 0. Peidel 8. cambridge University cambridge, England Contact: C. C. Smith 9. case-western Reserve University cleveland, Ohio contact: A. R. Troiano 10. Caterpillar Tractor Co. Peoria, Illinois Contact: R. L. Straus 11. Carnegie-Mellon University Pittsburgh, Pennsylvania Contact: I. M. Bernstein 12. Cornell University Ithaca, New York Contact: H. H. Johnson 13. Drexel University Philadelphia, Pennsylvania Contact: H. C. Rogers 14. Frankford Arsenal Philadelphia, Pennsylvania Contact: F. E. Sczerzenie 15. French Atomic Energy Corrmiission Pruyeres-Le-Chatel, France Contact: J. P. Fiddle 16. Imperial College of Science and Technology London, England Contact: P. R. Swann 17. Institute of Gas Technology Chicago, Illinois Contact: D. P. Gregory 18. Lehigh University Bethlehem, Pennsylvania Contact: S. J. Hudak 19. Martin Marietta Coporation Baltimore, Maryland Contact: R. M. Latanision 20. Massachusetts Institute of Technology Cambridge, Massachusetts Contact: R. M. N. Pelloux 21. McDonnell Douglas Corporation St. Louis, Missouri Contact: T. C. Grimm 22. NASA - Ames Research Center Moffett Field, California Contact: H. G. Nelson PAGENO="1295" 1289 23. NASA - Lewis Research Center Cleveland, Ohio Contact: J. R. Stephens 24. National Bureau of Standards Boulder, Colorado Contact: R. P. Reed 25. National Bureau of Standards Washington, D.C. Contact: C. Interrante 26, Naval Facilities Engineering Command Washington, D.C. Contact: R. A. McCoy 27. North Carolina State University Raleigh, North Carolina Contact: R. B. Benson, Jr. 28. Naval Research Laboratory Washington, D. C. Contact: C, D. Beachem 29. Pennsylvania State University University Park, Pennsylvania Contact: H. Pickering 30. Rockwell International Rocketdyne Division Canoga Park, California Contact: W. T. Chandler 31. Rockwell International, Science Center Thousand Oaks, California Contact: N. E. Paton 32. Sandia Laboratories Livermore, California Contact: J. H. Swisher 33. Savanah River Laboratories (DuPont) Aiken, South Carolina Contact: H. R. Louthan 34. T. R. W,, Inc. Cleveland, Ohio Contact: C. S. Kortovich 35. University of Wisconsin Madison, Wisconsin Contact: D. Westphal 36. University of Illinois Urbana, Illinois Contact: H. W. Birnbaum 37. University of Maryland College Park, Maryland Contact: C. C. Chen 38. University of Paris Orsay, France Contact: J. P. Laurent PAGENO="1296" 1290 39. University of Minnesota Minneapolis, Minnesota Contact: W. W. Gerberich 40. University of California Los Angeles, California Contact: A. S. Tetelman 41. University of Technology Loughborough, Leics, England Contact: R. Haynes 42. U.S. Steel Corporation Monroe, Pennsylvania Contact: R. A. Oriani 43. Westinghouse Research Laboratory Pittsburgh, Pennsylvania Contact: W. G. Clark 4.9.5 Embrittlement Inhibitor Projects Title: Inhibition of Hydrogen Enbrittlement in Alloys Contact: K. E. Parr Institution: U.S. Army, Structures and Mechanics Laboratory, Redstone Arsenal, Huntsville, Alabama 35809 Summary: This research effort is directed to the gathering of experimental data to evaluate the effectiveness of a thin nitrided surface layer in subduing or stopping hydrogen embrittle- cent in the Ti-6Al-4V alloy. Title: Navy Environment: Hydrogen Embrittlement of High Strength Steels Contact: H. W. Pickering Institution: Pennsylvania State University, School of Earth Sciences, 201 Shields Bldg., University Park, Pennsylvania 16802 Summary: The objective of this research is to assess methods of reducing hydrogen embrittle- cent damage in high strength steels used in naval structures by control of surface properties. Techniques will be investigated for codifying the surface of steels in order to reduce (A) the rate of hydrogen adsorption, (B) the ease of hydrogen absorption, and (C) the diffusivity of hydrogen. Methods of approach will include specific solute additions to surfaces, hydrogen getter surface layers, and inhibitor layers. The ability of these methods to control hydrogen entry and transport will be assessed by electrochemical methods, permeation measurements, and fractography of ruptured specimens. * 4.9.6 Hydrogen Diffusion Projects Title: Controlled Thernonuclear Research - General Research and Development Studies of Deuterium and Tritium Management for Thermonuclear Reactors Contact: K. C. Vogel Institution: U.S. Atomic Energy Commission, Argonne National Laboratory, Lemont, Illinois 60439 Summary: This program involves an in depth study of the mechanisms and rates of diffusion of hydrogen isotopes through a wide variety of materials of potential utility in the con- struction of fusion reactors. In the early stages, hydrogen permeabilities will be mea- sured for niobium and vanadium as a function of both temperature and hydrogen partial pres- sure. The interactions of hydrogen with these materials will also be investigated by x-ray and micrographic techniques. Title: Lattice Dynamical Theory of the Diffusion Phenomena Contact: B. N. Achar Institution: U.S. Atomic Energy Commission, Argonne National Laboratory, Lemont, Illinois 60439 Summary: The theory of diffusion of interstitials will be studied in greater detail. Numerical applications will be made to diffusion of hydrogen and deuterium in palladium. PAGENO="1297" 1291 Title: Diffusion of Interstitial Components in Titanium and Zirconium Alloys Contact: S. J. Hruska Institution: Purdue University, Materials Science Center, Executive Bldg., Lafayette, Indiana 47907 Summary: The objective of this research was to determine the Ti-Zr phase diagram with greater precision and to measure the diffusivity of hydrogen in Ti-Zr alloys. Other Active Facilities 1. Institute fur Eisenhlttenkunde der Rheinsch-Westfilschen Technischen-Hochschule Aachen, Germany Contact: K. W. Lange 2. NASA - Ames Research Center Moffett Field, California Contact: H. G. Nelson 3. University of Nebraska Lincoln, Nebraska Contact: D. L. Johnson 4.9.7 Hydrogen and NDT Failure Detection Projects Title: Development of an Electrochemical Device for In-Situ Determination of Embrittling Hydrogen Content in Naval Aircraft Steel Components Contact: D. Berman Institution: U.S. Navy, Air Vehicle Technology Department, Warminster, Pennsylvania 18974 Summary: To develop an electrolytic contact cell for the determination of hydrogen in high strength steel aircraft structures and to correlate this with the degree of embrittlement. Title: Study of Acoustic Stress Wave Emission Phenomena and Its Application to the Early Detection of Corrosion and Fatigue Contact: K. Klinman Institution: U.S. Navy, Air Vehicle Technology Department, Warminster, Pennsylvania 18974 Summary: To study the fundamental mechanisms of acoustic stress wave generation and pro- pagation in order to improve applicability of the method for detection and investigation of stress and intercrystalline corrosion cracking, hydrogen embrittlement, and fatigue phenomena. Title: Nuclear Microprobe Hydrogen Detection Technique Contact: G. M. Padawer Institution: Grumman Corporation, S. Oyster Bay Rd., Bethpage, New York 11714 Summary: To acquire capability for detection and analysis of hydrogen at surface of high strength metallic critical aerospace weapons systems parts. Title: Applicability of Backscatter Mossbauer Effect to NOT for Hydrogen Embrittlement of Navy Materials Contact: K. C. Foiweiler Institution: Sanders Associates, Inc., 701 Concord Ave., Cambridge, Massachusetts 02138 Summary: Provide a convenient, practical technique for the appraisal of the deterioration modes of high strength steel. Hydrogen embrittlement, stress-corrosion hydrogen and re- sidual stress are the principal controllable factors of Navy materials. Title: Stress-Corrosion Behavior of Prestressed Wires Contact: S. Elices Institution: Center for Public Works Studies, Madrid, Spain Summary: The behavior of high-quality steel wires is being determined under different con- ditions; stress, corrosion brittleness through hydrogen, and cathodic polarization. An easy and rapid test procedure, which is representative of the above phenomena, is to be developed for use as a standard specification in Spain. 62-332 0 - 76 - 82 PAGENO="1298" 1292 Other Active Facilities 1. Naval Air Development Center Warminster, Pennsylvania Contact: D. A. Berman 2. Oak Ridge National Laboratory Oak Ridge, Tennessee Contact: G. L. Powell 4.9.8 Hydrogen Production and Transmission Projects Title: Energy Conversion, Energy Storage and Reconversion Contact: W. L. Hughes Institution: Oklahoma State University, School of Electrical Engineering, Whitehurst Hall, Stillwater, Oklahoma 74074 Summary: To develop a family of systems for storing electrical energy and thereafter re-utilize the stored energy in various ways. In storage, major emphasis has been in the development of high-pressure (1000 to 3000 PSI) moderate temperature (300 to 400 degrees Fahrenheit) electrolysis cells, fuel cells and rechargeable fuel cells for the storage of electrical energy in the form of high-pressure hydrogen gas (other alternatives include hydrides and liquid hydrogen). Title: Thermochemical Hydrogen Production Institution: Institute of Gas Technology, Chicago, Illinois Summary: Hydrogen can be produced by the decomposition of water using the heat generated in a nuclear reactor. Multi-step chemical processes are being theoretically and experi- mentally examined. All intermediate chemicals are recycled so that the overall reaction scheme produces only hydrogen and oxygen with water as the only raw material. A number of different reaction schemes have been considered. Two of them have potential promise and are being analyzed in more detail. Title: Energy Conversion and Storage Contact: W. L. Hughes Institution: Oklahoma State University, School of Engineering, 101 Gunderson Hall, Stillwater, Oklahoma 74074 Summary: The original prime objective of the project was to develop an economical com- mercial electrolysis-fuel cell, the purpose of which would be to utilize off-peak electric energy and water in the electrolysis mode to produce oxygen and hydrogen which would be stored. Title: Production of Hydrogen from Water Contact: 1. L. Russell Institution: Gulf General Atomic, Inc., San Diego, California Summary: To discover and develop closed thermochemical cycles for producing hydrogen from Title: Ocean Sited Power Plants Contact: N. E. Heronemus Institution: University of Massachusetts, School of Engineering, Amherst, Massachusetts 01002 Summary: The augmented effort will be applied to marine system conceptualizations and feasibility studies of power generation from ocean temperature differences where the boiler and condenser temperatures are about 75-85 degrees F (tropical surface waters) and 35-45 degrees F (bottom waters below 2000 feet), respectively. All components of a system will be conceptualized and evaluated including hulls, heat exchangers, pumps, pipes, electrolysis of water to hydrogen fuel, etc., for a 100-400 MW central power stations moored in the Gulf Stream. PAGENO="1299" 1293 Title: A Hydrogen Energy Distribution System Institution: Institute of Gas Technology, Chicago, Illinois Summary: This study was undertaken to assess the feasibility of producing hydrogen from nuclear energy and to determine whether any technical roadblocks exist which would prevent its long-distance transmission and its in-city distribution and utilization. Other Active Facilities 1. General Electric Company Schenectady, New York Contact: A. R. H. Wentorf 2. Euratom C.C.R. Establishment of Ispra, Italy Contact: C. Marchetti 3. Los Alamos Scientific Laboratory Los Alamos, New Mexico Contact: Mel Bowman 4.9.9 Hydrogen Storage Projects Title: Chemical Energy Storage Contact: J. N. Burger Institution: Public Service Electric and Gas Company, 80 Park Place, Newark, New Jersey 07101 Summary: Develop a reliable, low cost chemical energy storage device to store electrical energy during off-peak times and to deliver electrical energy for a duration of 10 to 12 hours during heavy-load times. Also included is the development of a gas electric two-way trans- former system utilizing hydrogen storage to produce electrical energy or pipeline gas. Title: Vacuum Shell Cryogenic Tankage Fabrication for Possible Orbit to Orbit Shuttle Use Contact: J. Kennedy, T. Nicastro Institution: Signal Companies Incorporated, 1010 Wilshire Blvd., Los Angeles, California 90017 Summary: Technical objective: The purpose of this effort is to fabricate a vacuum jacketed tank with application to long term storage of liquid hydrogen. After fabrication and delivery of the tank to the AFRPL a test program will be Initiated to determine thermodynamic performance of the tank using liquid hydrogen. Title: Cryogenic Storage Technology Contact: C. A. Aukerman Institution: U.S. National Aeronautics and Space Administration, Lewis Research Center, Cleveland, Ohio ) Summary: The general objectives of the programs under this RTOP are to provide technology for various aspects of cryogenic thermal protection systems. The specific areas covered by these programs are: (1) shadow shields for liquid hydrogen tanks, (2) a liquid hydrogen mixing unit, (3) cryogenic tank supports, and (4) integrated thermal protection systems. In each area, the objective is to demonstrate the feasibility of a new concept for improv- ing the capability to store liquid hydrogen in space vehicles. PAGENO="1300" 1294 Title: Tankage Development and Evaluation Contact: C. T. Smith Institution: U.S. National Aeronautics and Space Administration, Lewis Research Center, Cleveland, Ohio Summary: Design and fabrication of low cost, high performance reliable pressure vessels for upper stage vehicles. Characterization of the growth of flaws which are deep with respect to the material thickness. Both critical and subcritical flaw growth data will be obtained in both aggressive and inert environments. Title: Metal Hydrides Contact: J. J. Egan, D. R. MacKenzie Institution: Brookhaven National Laboratory; Upton, New York 11973 Summary: We plan to obtain PTC or exchange data or both on the hydrides of such metals as the alkaline earths, thorium, zirconium alloys, vanadium alloys, ABS-type and other rare earth alloys, and perhaps some ternary alloys. As regards hydrogen storage, experi- ments are planned which will increase our knowledge of the effects of minor components of alloys on hydride reservoirs in conjunction with energy sources which will be investigated both by engineering analysis and if possible with actual bench-scale integrated systems. 4.9.10 Propulsion Systems Projects Title: Non-Polluting Engine Program Contact: 3. Agost, also with H. C. Wieseneck, Rockwell International Corporation Institution: Commonwealth Edison Company, 3500 N. California Ave., Chicago, Illinois 60632 Summary: Commonwealth Edison Co., and Rocketdyne Division of North American Rockwell Corp. are working on this joint plan to install an experimental "rocket" powered or non- polluting engine (NPE) to produce peaking power electricity at Edison's Joliet Station. Title: Advanced H-U Power System Technology Contact: U. C. Beremand Institution: U.S. National Aeronautics and Space Administration, Lewis Research Center, Cleveland, Ohio Summary: This activity is directed toward the continued investigation and advancement of Hydrogen-Oxygen Turbine engine technology. This work is in support of advanced H-U Space Power Systems (such as advanced Shuttle APU's) as well as the widening interest in non- pollutiUg H-U ground power systems. Potential areas of investigation include Stoicho- metric H-U engines with water-injection-cooled combustors, utilization of water-cooled turbines, and materials development for hydrogen turbines. Title: Space Shuttle Auxiliary Propulsion Contact: U. L. Nored Institution: U. S. National Aeronautics and Space Administration, Lewis Research Center, Cleveland, Ohio Summary: The objective of this program is to provide improvements in the technology of engine components for the auxiliary propulsion system of the space shuttle. The major portion of this work will be devoted to advancements in the thruster assembly, including the injector, thrust chamber, igniter, and valves. The operating conditions for experi- mental work are selected to fit the particular requirements of the space shuttle. This includes operation with gaseous hydrogen/gaseous oxygen propellants at thrust levels in the range from 1500-2000 pounds, chamber pressures from 100-150 psia, and appropriate ranges of propellant inlet pressure and temperature. Title: Space Storable Propulsion Technology Contact: E. W. Conrad Institution: U.S. National Aeronautics and Space Administration, Lewis Research Center, Cleveland, Ohio Summary: The objective of this program is to provide component, subsystem and system design criteria for propulsion systems using moderate cryogenic (space storable) and deep cryogenic (hydrogen) propellants to demonstrate the performance and technology readiness of propulsion modules using both propellant types for simulated mission of up to 1200 days. PAGENO="1301" 1295 Title: Advanced Liquid Rocket Propulsion Component Technology Contact: J. W. Gregory Institution: U.S. National Aeronautics and Space Administration, Lewis Research Center, Cleveland, Ohio Summary: The objective of this program is to provide improvements in the technology of liquid rocket propulsion, including (1) turbomachinery, (2) feed systems, (3) injectors and thrust chambers, and (4) associated instrumentation. In turbomachinery, the major efforts will be devoted to investigation of axial flow pumps, inducer design, cavitation in cryogenic propellants. Title: Advanced Combustors and Fuels Contact: J. H. Childs Institution: U.S. National Aeronautics and Space Administration, Lewis Research Center, Cleveland, Ohio Summary: Research will be conducted on film cooling of combustor liners, multiple jet penetration and mixing, new types of fuel injectors, and short-length, bleed-type combustor inlet diffusers. Concluding research will be done on fuel system components and handling techniques for liquid methane and liquid hydrogen fuels. Title: Space Systems Propulsion Contact: M. J. Saari Institution: U.S. National Aeronautics and Space Administration, Lewis Research Center, Cleveland, Ohio Summary: The objective of this study is to provide a point design of an LH2/LO2 engine of about 10,000 pounds thrust. Title: Development of a Pollution Free Hydrogen-Fueled Automobile Contact: R. R. Adt, Jr. Institution: University of Miami Summary: The object of this work is to optimize the design of the hydrogen-fueled engine, fuel storage and delivery system. 4.9.11 Bearings, Seals and Lubricants Projects Title: Bearings, Seals, and Lubricants Contact: R. L. Johnson Institution: U.S. National Aeronautics and Space Administration, Lewis Research Center, Cleveland, Ohio Summary: Basic materials and lubricants studies as well as experiments and analyses with actual components in vacuum, cryogenic, inert gas, and low viscosity fluid environments will be conducted. The potentials of self-lubricating materials and film deposition methods are being explored. Experisien ts and analyses of promising types of fluid film bearings and seals for gas and low viscosity liquid applications are underway. Title: Shuttle Lubrication, Bearings and Seals Contact: R. L. Johnson Institution: U.S. National Aeronautics and Space Administration, Lewis Research Center, Cleveland, Ohio Summary: Materials and lubricants selection, development, design, theory, analysis and experimentation of bearings and seals will be performed under extreme conditions associated with (A) engine and (B) vehicle components subject to lubrication, friction, wear, and hydraulics problems. Rolling element bearings and face type seals for hydrogen pumps of shuttle engines will be operated under conditions simulating problem areas. PAGENO="1302" 1296 4.9.12 Fuel Cells Projects Title: Direct Energy Conversion Research Contact: N. Altman, G. L. Schrenk, H. Wroblowa Institution: University of Pennsylvania, School of Engineering, 107 Towne Bldg., Philadelphia, Pennsylvania 19104 Summary: Electrocatalytic Materials for Oxygen Electrodes. Involves an investigation of the electrochenical behavior and of structural changes occuring in doped Cu, Au alloys during oxygen reduction in low temperature alkaline cells, aiming at development of a stable oxygen electrode containing no noble metals of Group VIII and outperforming platinum based electrodes. The second goal is an examination of the theory of Bocciarelli which led to construction of new electrocatalysts for oxygen and hydrogen electrodes. Flow-Through Systems. The research covers the theory of flow-through electrodes by including the diffusional effects hitherto neglected: development of a method of deter- mination of the electro-active surface area of porous electrodes and production of low catalyst load flow-through and gas diffusion electrodes. Applied Surface Physics. Transport phenomena of electrons through surfaces will be investigated with emphasis on applications in field ion microscopy and electrocatalysis. This will involve research in the kinetics and quantum mechanics of surface reaction, adsorption/desOrPtiOn processes, and tunneling through multi-layer adsorbates, both in vacuo and in the presence of solvents. Title: Reactive Sensitivity of Fuel Cell Gas Mixtures Contact: J. S. Greer Institution M S A Research Corporation, Evans City, Pennsylvania 16033 Summary: Mixtures of gases arising during the routine operation of candidate naval fuel cells such as hydrazine-peroxide and hydrogen-oxygen types will be examined with respect to the effect of pressure on their flammability limits. Where flammability is observed, the ignitibility characteristics of the system will be studied as a function of pressure. Ignition will be effected by spark, compression and thermal gradient. In addition, the effect of selected catalysts and hypergolic (e.g., peroxide vapor) impurities on the flammable mixtures will be observed. Negotiations are underway for an experimental study of the effects of high pressure (in the range of 10,000 psi). Title: Low Cost Matrix for Hydrocarbon Fuel Cell Contact: B. S. Baker Institution: Energy Research Corporation, Bethel, Connecticut 06801 Summary: The purpose of this contract is to develop an H3P04 matrix technology. Suitable matrices must be structurally and chemically invariant in hot H3P04, be composed of low cost raw materials, and be capable of inexpensive mass production. A second part of this contract will examine low cost CO tolerant anodes for indirect hydrocarbon/air fuel cells. Those naterials exhibiting desirable characteristics will then be tested in single H /air cells. Small amounts of platinum and platinum alloys will be supported on carbon an3 the resulting electrodes tested with H2-CO nixtures. Title: Fuel Cell Safety Contact: H. B. Urbach Institution: U.S. Navy, Ship Research and Development Laboratory, Annapolis, Maryland 21402 Summary: Provide improved safety characteristics of candidate naval fuel cell powerplants by development of data on material and component design selection and safety criteria guidelines applicable to power supplies for deep submergence vehicles, and underwater habitats. PAGENO="1303" 1297 Title: Thermocatalytic Hydrogen Generation from Logistic Fuels Contact: 0. F. Kezer Institution: U.S. Army, Mobility Equipment Research and Development Center, Fort Belvoir, Virginia 22060 Sunonary: The objective of this investigation is to produce a lightweight, efficient gas generation system operating on logistic hydrocarbon based fuels capable of producing hydrogen for a fuel cell reactant, The first phase of this investigation is the derivation of fundamental design and operational parameters for thermocatalytic hydrogen generators. This effort will be centered around the investigation of basic parameters, techniques and materials, applicable to the design and operation of thermocatalytic hydrogen generation systems. This includes an investigation of the effect of fuel, catalyst, and temperature on the products formed and will also involve a study of the mechanism of hydrocarbon cracking. Title: Regenerative Fuel Cells Follow-On for Satellite Secondary Power Contact: J. K. Stedman Institution: United Aircraft Corporation, Hartford, Connecticut 06118 Summary: Build an exploratory development base to support advanced development of a 20 watt-hr/lb hydrogen-oxygen regenerative fuel cell for energy storage for synchronous orbit applications. Title: Twenty watt-hr/lb Regenerative Fuel Cell (EOS) Contact: R. Costa Institution: Xerox Corporation, 3452 E. Foothill. Blvd., Pasadena, California 91107 Summary: To develop an energy storage system capable of long life (5-7 years) cyclic storage and release of 20 watt-hours or more of electrical energy per pound of storage system on board synchronous orbit satellites. To design, develop, test and evaluate a single cell (nominal 1 volt unit) regenerative hydrogen-oxygen fuel cell (about 350 ampere-hour capacity) utilizing a RON electrolyte matrix and concentric electrodes in a cylindrical configuration, Title: Twenty watt-hr/lb Regenerative Fuel Cell (P+w) Contact: J. Stedman, Pratt & Whitney Aircraft Div. Institution: United Aircraft Corporation, Hartford, Connecticut 06118 Summary: To develop an energy storage system capable of long life (5-7 years) cyclical storage and release of 20 watt-hours or more of electrical energy per pound of storage system on board synchronous orbit satellites. To design, develop, test and evaluate an integrated regenerative hydrogen-oxygen fuel cell stack utilizing separate electrodes for charge and discharge and KOH critical components and a functionally complete regenerative fuel cell system. Title: Electrode-Electrolyte System for H2-Air Fuel Cell Contact: 0. J. Adlhart Institution: Englehard Industries, Inc., Newark, New Jersey Summary: The technical objective is to attain 180 ma/square centimeters from fuel cells using a simulated cracker fuel (90 percent hydrogen, 10 percent methane plus trace of carbon monoxide) and air as the oxidant at voltages of .60 or higher after 2000 hours. Total noble metal catalyst loading are not to exceed 8 mg/square centimeters. Title: Electrochemical Power Devices Contact: H. J. Schwartz Institution: U.S. National Aeronautics and Space Administration, Lewis Research Center, Cleveland, Ohio Summary: Emphasis will be placed on technology leading to an advanced H2-02 fuel cell system for space shuttle applications. PAGENO="1304" 1298 Title: Low Cost Cathode Catalysts Contact: B. S. Baker Institution: Energy Research Corporation, Bethel, Connecticut 06801 Summary: The objective of this contract is to demonstrate high performance with low cost fuel cell air electrodes. The specific goals are to develop cathodes with a catalyst cost equivalent not more than $150/kW based on performance after 500 hours of constant current drain in H3P04 electrolyte. Title: Hydrogen-Oxygen Fuel Cells for Underwater Applications Contact: D. R. Gormley Institution U.S. Department of Defense, Naval Ship Research and Development Center Summary: The objective of this work is the exploratory development of naval hydrogen- oxygen fuel cell powerplant modules over the range of 2 to 20 kW with capabilities reaching 20 lb. and 0.2 Cu. ft. per kW rated output, 0.8 lb. consumables per kW, and a maintenance free life of 3000 hours. Title: Fuel Cell Materials for Underwater Power Sources Contact: J. R. Bowen Institution: U.S. Department of Defense, Naval Ship Research & Development Center, Naval Ship R&D Laboratory, Department of Machinery Technology, Annapolis, Maryland 21402 Summary: Study the electrochemical and compatibIlity behavior of candidate fuel cell materials for application in fuel cell power plants operation in deep-sea pressures as high as 10,000 psi. Present efforts involve materials for hydrogen-oxygen and hydrazine- hydrogen peroxide fuel cells. Title: Energy Storage and Generation Contact: W. L. Hughes, H. J. Allison. R. G. Ramakunar Institution: Oklahoma State University, School of Electrical Engineering, Stillwater, Oklahoma 74075 Summary: Research and development on high pressure electrolysis, high temperature and high pressure hydrogen-oxygen fuel cells, and development of a family of electric alternators for which output frequency is independent of prime mover shaft speed, physical size is about 1/4 that of conventional system (for same output frequency, power and efficiency). Title: Corrosion-Resistant Materials for Electrochemical Cells Contact: H. P. Silverman Institution: TRW, Inc., TRW Systems, One Space Park, Redondo Beach, California 90278 Summary: Methods for determining conpatability of materials with fuel cell electrolytes and the environment of electrochemical cells will be investigated. Title: Evaluation of Phosphoric Acid Matrix Fuel Cells Contact: 0. J. Adlhart Institution: Engelhard industries, 113 Astor Street, Newark, New Jersey 07114 Summary: To reduce the catalysts cost/kW of H -air fuel cells were expanded to include the examination of other reactants such as met1~anol and propane. Elevated temperatures, as high as 250 degrees C, shall be used in order to increase the oxidation rate of hydro- carbons. Title: Regenerative Hydrogen-Oxygen Fuel Cell Systems Contact: H. J. Allison, R. G. Ramakumar Institution: Oklahoma State University, School of Electrical Engineering, Whitehurst Hall, Stillwater, Oklahoma 74074 Summary: Testing and development of rechargeable hydrogen-oxygen fuel cells. Title: Family of Open Cycle Fuel Cell Power Plant Development Contact: T. Shillet Institution United Aircraft Corporation, Pratt & Whitney Aircraft, 400 Main Street, East Hartford, Connecticut 06108 Summary: To design, develop and fabricate 1.5 kW fuel cell power plants and to design 0.5 kW, and 5 kW power plants. PAGENO="1305" 1299 Title: Electrode-Electrolyte System for H2-Air Fuel Cell Contact: 0. J. Adlhart Institution: Engelhard Minerals & Chemicals Corporation, Engeihard Industries Division, 113 Astor Street, Newark, New Jersey 07114 Title: Fuel Cell Electrodes Contact: D. Laverty Institution: Brunswick Corporation, Materials Research Laboratory, Needham, Massachusetts 02102 Title: Thin Electrode Fuel Cells Contact: J. Batzold Institution: Esso Research & Engineering Company, P.O. Box 8, Linden, New Jersey 07036 Summary: The objective is to develop high performance alkaline, hydrogen-oxygen fuel cell electrodes based on the technology developed under National Aeronautics and Space Adminis- tration grant NSG-325. Principally, efforts will be directed towards reduction of electrode thickness, amount of catalyst and production problems for a given performance level. Title: Hydrogen-Oxygen Power Systems Contact: D. G. Beremand Institution: U.S. National Aeronautics and Space Administration, Lewis Research Center, Cleveland, Ohio Summary: The objectives are to develop technology readiness for a hydrogen-oxygen APU to provide hydraulic and electric.power for the space shuttle vehicle, and to evaluate the performance potential and applicability of hydrogen-oxygen dynamic power systems for other space and ground applications. 62-332 0 - 76 - 83 PAGENO="1306" 1300 CHAPTER 5 INSTRUMENTATION FOR CRYOGENIC HYDROGEN FUEL T. N. Flynn 5.0 SUMMARY This chapter surveys state-of-the-art technology for cryogenic hydrogen instruments. Recommendations for future work are outlined: adaptation of existing technology to commercial applications, development of new technology and integrating liquid hydrogen measurements into the National Measurement System (NNS) are future priority tasks. Since measurements are the basis of technology, and dictate the fineness of our physical observations and control, it is apparent that this part of hydrogen technology is lagging. Our three conclusions are: 1) little is being done to bring the hydrogen instrumentation technology of the space program to the market place, 2) if it were, ade- quate primary instruments and facilities do not exist to bring this part of the NMS under control, and 3) no concerted effort exists to explore the consequences or exploit the opportunities of new technological opportunities. These conclusions appear to apply generally to each area of cryogenic instrumentation, although, of course with varying degrees of severity. Specific analyses and conclusions appear in each major instrumentation area in the following sections of this chapter. The broad conclusions are: Pressure transducers are normally placed in a temperature controlled environment near room temperature. Some available pressure transducers are capable of performing satisfac- torily at low temperatures, but new types such as piezoelectric, diode, electrokinetic, etc. may perform equally well or better. It is, therefore, necessary for the purpose of comparison that all pressure transducers be tested at low temperatures and at various frequencies to determine their potential for hydrogen use. Because pressure sensing devices are widely used (differential pressure flow meters, level gauges, and vapor pressure thermometers) and because their cryogenic behavior is quite different from that of normal use, a systema- tic, well documented testing program is presently needed. Temperature measurements are unquestionably in better shape than any other hydrogen measurements. Adequate calibration facilities exist as well as a large body of knowledge that together help keep this part of the NMS in control. Industrial type platinum resis- tance thermometers ~re routinely used, for instance. Improvements in their interchange- ability would be desirable, as well as some simple thermometry for crude temperature indica- tions and the monitoring of process trends. Level detectors for liquid hydrogen were extensively developed during the space program, but it is remarkable how little space hardware is actually used in the commer- cial sector. A deliberate effort to adapt space instrumentation to commercial and indus- trial applications seems worthwhile. Primary instruments and facilities to calibrate liquid level devices do not exist, and accordingly it is questionable whether this part of the NMS is in control. Furthermore, a large body of knowledge and experience needs to be developed to move with assurance from PAGENO="1307" 1301 this relatively clean measurement to the practical measurement question of how much does the tank really contain? De~4~y~ is an Inferential measurement, and as such, it should be traceable to a national standard, such as a national density reference system. Primary instruments to calibrate densitometers do not exist. Several physical principles of hydrogen density measurement have been brought well forward by the space program. Notable are the capacitance, vibration, and nuclear radia- tion attenuation schemes. Microwave methods are recently moving to the forefront. It is felt that the pressing need now is to: a) commercialize these instruments for routine engineering applications and b) provide an adequate national reference system. Flow - There is no shortage of physical principles upon which to base a hydrogen flowmeter. Depending on the need, they range from simple pressure drop meters to sophisti- cated mass reaction types. Flow, however, is a derived quantity and as such flowmeters require traceability to a reference system to establish credibility. Thus flowmetering needs fall into four categories: 1) flow reference systems, 2) possible use of substitute fluids f or calibrations, 3) extension to large flow rates, 4) standard codes and practices. The latter requirement is basic to each area of instrumentation as hydrogen technology moves into the marketplace and becomes an influential member of the NMS. 5.1 INTRODUCTION The national space program developed not only a complete technological base for cryogenic instrumentation, but also many specific instruments themselves for particular tasks in hydrogen propellant loading and utilization. Nothing remarkable has been done, however, to bring these instruments to the market place for commercial and industrial use. A recent survey of the Smithsonian Science Information Exchange, Inc., revealed two hydrogen instrumentation projects. One was the development of a nuclear magnetic resonance (NMR) flowmeter for the USAF, and the other was a modest NBS effort. Thus one component of the problem of hydrogen instrumentation is that it is largely static. Not much has been accomplished technically since the peak of the space program, perhaps since 1969, or earlier, and surely there is little evidence of the commercializa- tion of these instruments. A second part of the problēm arises from the way hydrogen measurements fit into the NMS. As long as only a single agency or one sector of our economy (NASA, the aerospace industry) were using essentially all of the results of their own measurements, then that part of the NNS was internally consistent and in harmony with itself. ~ow however, the prospects are that hydrogen is becoming commercialized and moving to the market place and thus external consistency as well as internal consistency is now required to make this part of the NMS work. Primary instruments and facilities to calibrate the derived quanti- ties -- liquid level, density, and flow -- do not exist. Unlike pressure and temperature, this part of the NMS is chaotic and needs to be brought under control. The third part of the problem is perhaps a derivative of the first. Because the field is static, a crucial question is not being asked: are there predictable technological PAGENO="1308" 1302 developments that will either create a need for new hydrogen instruments or possibly provide an altogether new measurement means? 5.2 PRESSURE Pressure measurements in cryogenic systems have, for years, been made by simply running gage lines from the point where the pressure measurement is desired to some con- venient location at ambient temperatures and attaching a suitable pressure-measuring device such as the familiar Bourdon gage. This system works quite well for most applications; however, there are disadvantages to this straightforward approach that may introduce problems in many systems. The two most important are (1) reduced frequency response and (2) thermal oscillations. In addi- tion, heat leak, uncertainties in hydrostatic head within gage lines, and fatigue failure of gage lines could become significant in some applications. Such problems associated with pressure measurement at cryogenic temperatures could be eliminated by installing pressure transducers at the point of measurement, thereby doing away with gage lines. For these reasons, we shall consider in the following discussion primarily those pressure transducers which have an electrical output, and which can be "flush mounted" directly on the cryogenic component under consideration. 5.2.1 Pressure Transducers All pressure transducers, regardless of their particular type, share three major subassemblieS (1) a force summing device which converts the force or pressure to a displacement, (2) a mechanical link to transmit this displacement and perhaps amplify it, and (3) an electrical conversion device. The force summing device may take any of several forms. It may be, for example, a diaphragm, whether flat, corrugated, or encapsulated. It may also be a bellows, or a Bourdon tube, whether circular or twisted, or simply a straight tube which is stressed under pressure. The link may simply be a straight bar which transmits this displacement directly, or it may be an involved series of linkages which magnifies the original displacement. The electrical conversion device can also take many forms. It may be a variable capacitor whose plate spacing depends upon the displacement and, hence, pressure. It may be a variable potentiometer in which the position of the wiper arm is determined by the displacement and, hence, pressure. It may be any of several variable reluctance or variable inductance devices. It may also comprise a piezoelectric element, a strain gage, or a linear variable differential transformer (LVDT). Like all instruments, the output of a pressure transducer depends not only on the primary input, in this case pressure, but also upon extraneous effects, such as the effect of temperature on its various components. Erroneous pressure readings can be caused by both steady state temperature effects and temperature gradient, or thermal shock effects. PAGENO="1309" 1303 5.2.2 Steady State Temperature Effecta Steady state temperature effects can be measured by simply calibrating a pressure transducer at two or more different fixed temperatures, after a sufficient amount of time has elapsed such that every component of the transducer is at the same temperature. There will generally be noted both changes in sensitivity and also zero shifts. Dean [1] modeled pressure transducers in an analytical form and demonstrated that the sensitivity shift is primarily due to the differences in the thermal expansivities of the several components which make up the transducer, and especially due to change in the elastic modulus as a function of temperature. Likewise, the zero shift can also be attributed to the difference in the thermal expansivities of the several components of the pressure transducers, but the more significant effect in this case is the change in the dimensions of the components due to changes in temperature. If the electrical conversion device is used in some form of a bridge network, additional zero shifts can occur from the inability of the bridge to perform adequate common mode rejection. 5.2.3 Thermal Shock Effects So far we have been assuming that the pressure transducer is experiencing a uniform temperature throughout its many components. The effect of temperature gradients across a pressure transducer can be measured by applying no pressure to the pressure transducer, but subjecting it to a thermal shock by plunging it into a liquid cryogen. What is observed is purely the thermal shock, or thermal gradient, effect, Some pressure transducers are known to suffer a permanent deformation, or offset, after being returned to their normal operating temperature. It has been noted that many pressure transducers would, in fact, be quite good thermometers. Such erroneous readings can be explained if one considers a typical pressure transducer that is made up of a bellows, a link, and a linear resistor. Under conditions of thermal shock, the bellows will reach the new temperature environment at a different rate than the linear resistor. The difference in the expansivity of these materials are drastically different over a wide temperature range. Therefore, the contributions of the expansivities of these components to the sensitivity coefficient Is changed from the design condition, causing a sensitivity shift. A compensating resistor is often placed in the bridge in order to perform a common mode rejection to compensate for the temperature dependency of the elastic modulus of the bellows. Unfortunately, this compensating resistor Is often several inches away from the bellows, so that its temperature gradients are quite different from that member. In fact, if temperature gradients are expected for a pressure trans- ducer installation, it may be beneficial to remove the electrical compensation, as the error thus induced may far exceed the error due only to the temperature dependency of the elastic modulus. The temperature gradient effect also causes zero shift. These zero shift effects are usually dissipated with time as all of the members of the pressure transducer reach the same temperature. PAGENO="1310" 1304 5.2.4 Methods of Avoiding Temperature Effects on Pressure Transducers The most common solution to temperature effects is to avoid extreme-temperature en- vironments. When the pressure instrumentation point is subjected to such temperatures, the standard procedure is to run tubing from the pressure source to a remote, stable tem- perature location. This is good procedure if the instrument engineer is interested in a frequency response of the order of 10 Hz. Another approach is to flush-mount one pressure transducer in the extreme environment and another at the end of a tube as discussed above. The object is to measure static pressure levels with the tube-mounted pressure transducer and dynamic pressures with the flush-mounted transducer. The hope is that the temperature-shock contribution to dynamic response will be small or of low enough frequency to separate easily. A perhaps better but more complicated solution for cryogenic application is shown in Figure 5.1. A short thin-walled tube connects a cryogenic transfer line or tank to a pressure transducer. A heater and a thermostat are attached to the transducer, regulating the temperature to perhaps 27CC. Insulation surrounds the transducer. Tube length is long enough to reduce the power requirement to the heater to a few watts, hopefully without excessively reducing the frequency response. It is important that the heater and tube connection be arranged so that temperature gradients do not exist in the transducer. The transducer must be oriented so that the liquid cryogen does not flow into the diaphragm. 5.2.5 Pressure Summary Temperature, as an extraneous variable, can have a profound effect upon pressure transducers, altering both the sensitivity of the instrument and its zero setting. Sensi- tivity shifts are primarily proportional to the spring constant and thus the Young's modulus temperature dependency of the force summing member-be it a diaphragm, a bellows, a Bourdon tube, or a capsule. Zero shifts are primarily due to dimensional instability caused by temperature changes of the pressure transducer components, including the case or frame. Temperature gradient effects are the combination of the above effects while the transducer component temperatures are varying. Proper design can reduce zero shift by locating the electrical sensing element so that dimensional changes are not detected as an input. Sensitivity shifts can be electri- cally compensated assuming a resistor can be found that has the desired resistance-tempera- ture properties. Unfortunately there is not much that can be done about temperature gradient effects except to avoid them. Component material and compensating resistors that are carefully chosen for steady state temperature conditions lose their relationships under transient conditions. However, it may be helpful to place the compensating resistor as close to the force summing element as possible. Avoiding temperature gradients is a matter of heat transfer. Under cryogenic conditions enough insulation must be used to greatly extend the thermal time constant of the system. Of all the measurements made on cryogenic systems, surely one of the most common must be that of pressure measurement. Pressure measurements are made not only to determine the force per unit area in a system, but also to determine flow rate (head type meters), quantity PAGENO="1311" 1305 FIGURE 5.1 - Temperature- Regulated Pressure Transducer for Cryogenic Installation. WATER TUBE OR THERNOSTATED ELECTRIC HYDROGEN PIPELINE PAGENO="1312" 1306 (differential pressure liquid level gages), and temperature (vapor pressure or gas thermo- meters). Pressure measurements are thus fundamental to the smooth running of much of this part of the National Measurement System (NMS). While it is agreed that some available pressure transducers are capable of performing satisfactorily at low temperature, other types, e.g., piezoelectric, diode, inductance, reluctance, and electrokinetic devices may perform equally well or better. It is, there- fore, necessary for the purpose of comparison, that all pressure transducers types be tested at low temperature and at various frequencies to determine their potential for cryo- genic use. Because pressure sensing devices often behave quite differently (from ambient conditions) in a cryogenic medium, a systematic, well documented testing program is pre- sently needed before all types can be evaluated and compared. A cryogenic calibration system with varied capabilities is essential for the success- ful completion of such a program described above. The details of such a system have been described by Arvidson [21. 5.3 TEMPERATURE Most engineering measurements are made with metallic resistance thermometers, non- metallic resistance thermometers, or thermocouples. Gas thermometers and vapor pressure thermometers find little practical engineering application, and hence are mentioned only briefly in the following paragraphs. A recent compilation of the commercial availability of thermometers is given in "Measurements and Data" [3]. 5.3.1 "FLUID" THERNOMETRY Gas Thermomery~. Constant-volume gas thermometry is familiar as a technique for accurate realization of the thermodynamic temperature scale. In such work the P-T behavior is made as linear as possible by minimizing the extraneous volumes in the mano- meter and the connecting tubing. Troublesome corrections for these extraneous volumes decrease with decreasing bulb temperature inasmuch as the proportion of gas in the bulb increases. On the other hand, gas imperfection increases with decreasing temperature. If, however, the sensing bulb is made small as compared to the external volume of the system at ambient temperature, the characteristic is far from linear, the sensitivity increasing greatly as the bulb temperature decreases. By using a Bourdon gage to show the pressure in this device, a simple gas thermometer is achieve' which is useful for such purposes as monitoring the cool-down of cryogenic apparatus. In order to obtain accurate results in gas thermometry it is necessary to correct for (1) the imperfection of the gas, (2) the effect of the "nuisance volume" or the volume of gas which is not at the temperature being measured, (3) the change of volume of the bulb with changing temperature, (4) variations in the amount of gas adsorbed on the walls of the gas thermometer bulb, and (5) the thermomolecular pressure gradient encountered at extremely low pressures. Accordingly, for engineering applications, gas thermometry is recommended for indicating the approximate temperature, or temperature trend. For precision temperature measurements, the corrections required are usually too bothersome. PAGENO="1313" 1307 Precision Gas Thermometry falls in the category of fundamental thermometers rather than empirical thermometers. It is much too demanding for common use. Vapor-Pressure Thermometry. As is well known, vapor pressure is a sensitive but non- linear function of temperature providing convenient means for thermometry in limited ranges of temperature which, unfortunately, do not join to provide continuous coverage of cryogenic temperatures. For example, the range from 40 K to 50 K is above the range of neon and below that of oxygen and nitrogen. Within its limits, however, this type of thermometer is very accurate. In fact, one of the greatest advantages of vapor-pressure thermometers at low temperatures is their extreme sensitivity in the range over which they can be used. A temperature change of 1 Kelvin will result in a sizeable pressure change. These thermometers are most accurate in the area of the normal boiling point of the liquid used, and hence could be very useful, albeit over a very limited temperature range. Hydrogen is especially troublesome because of the dependence of vapor pressure upon ortho-para composition; however, hydrogen vapor pressure thermometers have been successfully used under carefully controlled conditions where high accuracy over a very narrow span was sought. Advantages of this type of thermometry are that it is sensitive, can have good time response, is not affected by magnetic fields, and needs no calibration. The primary dis- advantage is that it can be used only between the triple point and critical point of the fill liquid. 5.3.2 Metallic Resistance Thermometry Since the resistivity of an element or compound varies with change in temperature, it has in many instances been used as a simple and reliable temperature-measuring device. Many elements or compounds, however, are not suitable for use in low-temperature resis- tance thermometry since they lack one or more of the desirable properties of an ideal resistance thermometer. These properties include: 1. A resistivity that varies linearly with temperature to simplify interpolation. 2. High sensitivity. 3. High stability of resistance so that its calibration is retained over long periods of time and is not affected by thermal cycling. 4. Capability of being mechanically worked. While there exist a number of metals that are more or less suitable for resistance thermometry, platinum has come to occupy a predominant position, partly because of excel- lent characteristics, such as chemical inertness and ease of fabrication, and partly be- cause of custom: that is, certain desirable features such as ready availability in high purity and the existence of a large body of knowledge about its behavior have come into being as its use grew and have tended to perpetuate that use. Its sensitivity down to 20 K and its stability are excellent. Its principal disadvantages are (1) low resistivity, (2) insensitivity below about 10 K, and (3) a variation of the form of the resistance- temperature relation from specimen to specimen below about 30 K. PAGENO="1314" 1308 The significance of the first item is that the excellent sensitivity in the liquid- hydrogen region cannot be realized unless the resistor has a high ratio of length to cross- sectional area. If it is a wire, it must be long and thin, which results in a bulky and delicate resistor coil and complications in supporting and insulating it. If it is a film, nonreproducible behavior due to differential contraction stresses between the film and substrate is difficult to prevent. The second disadvantage can be avoided only by using a different metal in which the lattice vibrations persist to lower temperatures, inasmuch as these are responsible for the temperature-dependent part of the resistivity: that is, a low value of the Debye parameter 0~ is required. Indium has been proposed and ought to have useful sensitivity almost down to its superconducting transition at 3.4 K. However, attention has been diverted from it by the advent of successful germanium thermometers, and it has undergone little or no commercial development. The third disadvantage is at present the most troublesome one since it can demand that each thermometer be separately calibrated. A variety of platinum resistance thermometers (PRT) designed for engineering applica- tions is now available. As with other transducers, these devices are subject to extraneous effects (noise). In this case, we wish to measure only the temperature dependence of the resistivity. However, we may also unwittingly measure the strain dependency as well. To avoid this, the engineering thermometers are built to imitate the strain free construction of the precision laboratory type thermometers. There are two basic designs for engineering use: immersion probes and surface tem- perature sensors. The immersion probes feature a high purity platinum wire encapsulated in ceramic, or securely attached to a support frame. Features such as repeatability after thermal shocks, time response in different environments, interchangeability, and mechani- cal shock tolerance differ between companies and specific designs. For the most part, the specifications below represent typical values which might be used in preliminary designs, but exact specifications must necessarily come from the manufacturer. The repeatability of the typical immersion sensor is usually certified to be about ± 0.1 K at the ice point after several thermal cyclings to cryogenic temperatures. For most thermometers this repeatability figure is conservative. The time response Is particularly difficult to assess in a general way because it depends critically upon the design and on the method of testing. Flowing water, oil, or cryogenic liquids are often used as the test medium. The time response of the capsule type PRT was previously given as 2 to 7 seconds, which meant that in this time the sensor had reached the equilibrium temperature of the system (ignoring 12R heating). In the case of the industrial PRT, dynamic systems are frequently encountered. Convention has been to define the time response of a thermometer to be the time it takes the sensor to reach 63.2% of the temperature of a step function temperature change. With this definition of the time constant, a typical range of values for this type of resistor is 0.1 to 3 seconds. Interchangeability is measured in terms of errors involved when more than one thermometer is used with a single K versus T relationship. This becomes a major concern in operations where control resistors must be replacable PAGENO="1315" 1309 without system interruption, and where data reduction and calibration expense must be minimized. Interchangeability is ordinarily specified at a given temperature, i.e., the resistance of the thermometers will not vary more than a specified amount at a certain temperature. Immersion type sensors may generally be specified to have the same ice point resistance to within an equivalent of about ± 1.5 K; surface sensors show slightly worse interchangeability, ± 4 to 5 Kelvins at 0*C. Some manufacturers provide different grades of interchangeability for particular models. Even after specifying a particular resistance value at a given temperature, the slope of R versus T, which depends on purity and strain, may vary from one thermometer to another. The second type of industrial sensor is broadly known as a surface temperature sensor, whose geometry is such that they make good thermal contact with surfaces of various shapes. Sensors are available for clamping around small tubing, fitting into milled slots, and clamping under bolt heads. The principle advantages of these thermometers are that they are small, typically 0.25 cm x 1.25 cm x 1.25 cm with perhaps a factor of two variation in any dimension. Both the immersion and the surface sensors are available in versions which have built- in bridge circuits. These bridge circuits allow adjustments to be made on individual sensors to increase the interchangeability. Two, three, and four lead configurations are available in both the surface and immersion sensors. Joule heating must be guarded against in all types of resistance thermometers by limitation of the measuring current. 5.3.3 Non-Metallic Resistance Thermometry A number of semiconductors also have useful thermometric properties at low tempera- tures. A semiconductor has been defined as a material the electric conductivity of which is much less than that of a metallic conductor but much greater than that of a typical insulator. There are, however, at least three distinct differences between semiconductors and pure metals as resistance thermometers. First, the sensitivity, (l/R)(dR/dT), of a semiconducting thermometer in its useful range is usually much greater than that of a pure metal thermometer. Second, the temperature coefficient of resistivity of semiconductors is negative whereas for pure metals it is positive; for example, the dR/dT for a typical semiconductor is -50 x lO3/K at 273 K, whereas for platinum at the same temperature it is 4 x 1o3/K. Thus the resistance of a semiconductor decreases with increasing temperature while the opposite is true for a pure metal. Third, as mentioned in the definition for a semiconductor, the resistivity of a semiconductor is usually several orders of magnitude greater than that of a pure metal. Consequently, a semiconducting thermometer element is usually short and of relatively large cross section, so that its resistance will be readily measurable. The most promising semiconductors seem to be germanium, silicon, and carbon. The latter, though not strictly a semiconductor, is included in this group because of its similarity in behavior to semiconductors. Of the three, germanium has received by far the most attention, and germanium resistance thermometers are now available from several commercial sources. The resistance element is usually a small single crystal. Inasmuch as the resistivity is high, the element can be PAGENO="1316" 1310 short and thick. It is mounted strain-free in a protective capsule. Because of this combination of features, the germanium thermometer is both rugged and reproducible. The major disadvantage associated with the use of germanium thermometers is the lack of a simple analytical representation. Each thermometer must be calibrated by comparison at many points in the range of interest if the inherent reproducibility of the thermo- meters is to be utilized. Thermistors (thermally sensitive resistors) are essentially resistors made up of sintered metal oxides. Frequently used materials are nickel, manganese, and cobalt oxides. The tem- perature-resistance relationship for this type of resistor has a negative slope much like the carbon or germanium resistors. The fact that these resistors are becoming increasingly popu- lar in measurement and control circuits is attested to by the number of companies selling them [3]. The reasons for the increasing use are in part: 1) they are small which tends to make the time response significantly less than one second, 2) they are typically high resist- ance units which reduces the overall effect of lead resistances, and 3) their temperature- resistance characteristics are dependent on materials and procedures which allows thermometers to be developed which are particularly sensitive in limited ranges of temperature. There are, of course, disadvantages also. Items 2) and 3) above may be considered as disadvantages as well as an advantage: any one thermistor is not usable over a wide range of temperatures due to its resistance becoming exceedingly high. The temperature dependent behavior of thermistors is similar to that of the semiconductors discussed above. Manu- facturing processes allow the tailoring of thermistors to be useful over a wide range of temperatures. 5.3.4 Thermocouples Thermocouples have the familiar advantage that the temperature-sensing junction can be reduced in size to almost any desired extent, so that the disturbance to the object being sensed can be made very slight, and the response time can be very fast. They also have a familiar disadvantage, namely, that rather small voltages must be measured. This disadvantage is accentuated at low temperatures where the thermoelectric power, dE/dT, is usually smaller than elsewhere. In addition, they have a less familiar but very serious disadvantage, namely, that the net emf depends not merely on the materials nominally used f or the two wires but also on material inhomogeneities which, if located in a temperature gradient, will introduce parasitic voltages. These inhomogeneities may arise from variations in chemical composition or may consist of crystal lattice imperfections introduced, for example, by kinking the wires. Their presence can be detected by various tests but cannot readily be corrected for, so that testing merely serves to indicate whether a given wire should be discarded or not. The emf-temperature relationships of thermocouples are seldom simple over wide ranges and, hence, functional representation is not usually attempted. Instead, a tabular relation- ship obtained by careful calibration of a thermocouple representative of a particular type is adopted as a standard, and the fabrication of thermocouples of this type is controlled to duplicate within close limits the characteristics of the standard. Where the emf-tempera- ture relation must be known more closely, the user may calibrate the thermocouple at a few PAGENO="1317" 1311 well-spaced temperatures and, by reference to the standard table, construct a graph of emf differences. Then, by interpolating in this graph, a correction to any measured emf can be found, and by entering the standard table at the corrected emf, the temperature is found. Some thermocouples commonly used in the hydrogen region include: 1. Gold (2.1 atomic % cobalt) vs. copper: Large thermoelectric power; the gold-cobalt alloy tends to be less homogeneous than other commonly used materials and is unstable if heated above 70'C. 2. Constantan vs. copper: Good homogeneity is possible. 3. Constantan vs. iron, or Chromel vs. Alumel: Advantageous only where the thermo- couple is required to be used at both low and high temperatures. Copper also has serious disadvantages: (1) Its thermal conductivity is very high. This property reaches a maximum around 20 K and at this point may be from two to five times greater than at room temperature. Now, the temperature of a thermocouple junction is deter- mined partly by the heat conductance of the contact between the junction and the object or fluid to be measured. If the contact is noncrystalline and nonmetallic, its conductance will be low and will decrease with decreasing temperature. This would be true if, for example, the thermocouple were used to measure the temperature of a fluid or vapor, or if it were used to determine the temperature of a solid surface to which it was glued or clamped without metallic contact. Conversely, the conductance of the copper wire is high and increases with decreasing temperature (down to 20 K). Thus, the temperature of liquid hydrogen provides a bad set of conditions under which it is difficult to eliminate the heat flow and hence the temperature difference across the contact. (2) The thermoelectric power of copper is very sensitive to transition-metal impurities and especially to iron at low temperatures. Both of the above disadvantages of copper can be avoided by substituting a suitable alloy for it. The alloy, silver (0.37 at.% gold) called silver-normal is currently being used. 5.3.5 Temperature Summary Figure 5.2 summarizes some representative characteristics of the best known types of cryogenic thermometers. The terms "reproducibility" and "accuracy" require some explanation. By reproducibility is meant the variability observed in repeating a given measurement using the best present- day laboratory techniques. Changes produced on thermal cycling of the thermometer to and from ambient are included in this parameter. By accuracy is meant the significance with which the thermometer can indicate the absolute thermodynamic temperature. This includes errors of calibration as well as errors due to nonreproducibility, the former usually being much more significant. The approximate numbers given for these quantities represent good current practice. It may be possible to do better by extreme care. On the other hand, in most engineering measurements a lower order of accuracy is permissible, and this may allow relaxation of certain requirements such as strain-free mounting of resistors, homogeneity of thermocouple materials, purity of vapor-pressure fluid, sensitivity and accuracy of associated instruments, etc. PAGENO="1318" Some Approximate Characteristics of the Most Widely Used Classes of Thermometers BEST BEST RESPONSE RELATIVE TYPE RANGE REPRODUCIBILITY ACCURACYa TIME SIZE K ~K ~K Sec RESISTANCE THERMOMETERS Platinum 10-900 l0~-l0~ io2-io4 0.1-10 3 Carbom 1-30 io2_io3 io2-io3 0.1-10 2 Germanium 1-100 lO~-lO~ io2_io_3 0.1-10 2 THERMOCOUPLES Gold-Cobalt vs Copper 4-300 2 101_b 1 1O~ o1~1c 1 Down to a mills dia Constantam vs Copper 20-600 bo_l_lo_2 lO~ 013c 1 VAPOR PRESSURE Helium 1-5 l0~-b0~ l0~ 0.1-100 4 Hydreges Nitrogen 14-33 63-126 io~ bO_2_103 io_2 b0_2 0.1-100 0.1-100 4 4 1 cm3 and up Oxygen 54-155 1o_2_lo_3 io2 0.1-100 a-Including nonreproducibility, calibration errors and temperature scale uncertainty b-From 1 (smallest) to 4 (largest) c-Bare junctions Figure 5.2 Summary of Cryogenic Thermometry PAGENO="1319" 1313 For temperatures above about 20 K, the metallic resistance thermometers are more sensi- tive than the nonmetallic resistance thermometers. Temperatures above 20 K can be measured routinely with an industrial type platinum resistance thermometer with an accuracy of better than 100 mK and time responses somewhat better than 1 second. Accuracy at the millidegree level requires a precision capsule type PET and careful calibration. Carbon thermometers are generally used for low temperature measurements (T < 80 K) when accuracies of ± 0.1 K or ± 1% of the absolute temperature are needed. Millidegree accuracy is attainable using germanium resistance thermometers at temperatures below 20 K. The primary drawback to germanium thermometers is that no simple analytical representation is available which represents the resistance versus temperature characteristics even for a given class of doped germanium crystals. A many point comparison calibration is required if all the inherent stability of the resistor is to be utilized. Vapor pressure and gas thermometry offer sensitive methods of temperature measurement with the advantage that no calibration is necessary. Further advantages are that these transducers are not sensitive to magnetic fields or electric fields. In the case of vapor pressure thermometers, the time response may be made comparable to the resistance thermo- meters. A sensible recommendation about which type to use cannot be made without knowing the specific measurement requirements. The generalization most likely to hold true, however, is the following: For crude temperature indications and monitoring trends, a gas thermometer will probably be suitable. For more accurate work, vapor pressure or resistance thermometry is recommended. For engineering application in this latter area, the need is for inexpen- sive devices that do not call for unique calibration. 5.4 LIQUID LEVEL Liquid level is but one link in a chain of measurements necessary to establish the contents of a container. Other links may include volume as a function of depth, density as a function of physical storage conditions, and, sometimes discerning useful contents from total contents (e.g., pumpable liquid vs. liquid and dense gas contained). Fortunately, the actual discernment of the liquid-vapor interface (liquid level) is often the strongest link in this measurement process due to the significant progress made here in the course of the space program. Liquid level determinations are essential to propellant loading, management, and utilization, and to other diagnostic or control functions, such as engine cut off. As a result of this intense interest, hydrogen liquid level measurements can be made with an accuracy and precision comparable to that of thermometry, for instance, and often with greater simplicity. This period of development led to many different physical embodiments of liquid level sensors, and there are as many ways of classifying these devices as there are authors who write about them. One classification is by the principle of operation. This groups sensors according to the physics of the device, usually an impedance measurement (or mismatch) in some region of the electromagnetic spectrum. By this scheme, liquid level sensors are grouped as acoustic, optical, thermal, magnetostrictive, etc. This classification is helpful if one is developing new instruments and needs to search the electromagnetic spectrum for a new type. PAGENO="1320" 1314 Another classification which includes the above is useful if one is interested in the outcome rather than the input. Here, sensors are grouped by whether the output is discrete, or digital (point sensors) or whether the output is a continuous analog of the measurand (continuous sensors). We shall use this latter classification understanding from the outset that the principle of some point sensors can be stretched to make continuous sensors (e.g., capacitance mea- surements), and that no one type is intrinsically better than another for all cases. Special requirements of the particular application and engineering trade-of fs will govern the choice. This chapter will conclude with some comments on the need for further research and develop- ment in this area. 5.4.1 Point Liquid Level Sensors All liquid level sensors depend for their operation on the fact that there be a large property change at the liquid vapor interface, a significant change in density, for example. This may not always be the case if the fluid is stored near its critical point, for instance, or if stratification has built up after prolonged storage. Be that as it may, point level sensors are tuned to detect a ~ property difference and give an on-off signal. Several of the more commonly used types are described below. The thermal or hot wire type senses the large difference in heat transfer coefficient between liquid and vapor. Since the heat transfer coefficient is much larger in the liquid than it is in the vapor, one can expect, for a given power input, that the transducer will have a different temperature and hence resistance in the liquid than in the vapor. It is this change in electrical resistance which is actually sensed in a wheatstone bridge, and hence these devices can be made both simple and fast. Protection in the form of a stiliwell is usually provided to prevent splashing or drops falling on the hot wire (sensing element) from causing a false indication. Small platinum wires, solid carbon resistors and thin- film carbon resistors are examples of sensing elements that are used. The capacitive type depends upon the difference in dielectric constant between the liquid and vapor which is essentially a function of the fact that the liquid is more dense than the vapor. This sensor is usually made in the form of a bulls-eye, with alternate rings forming the plates of the capacitor, and are installed so that the plane of the rings is parallel to the liquid vapor interface. Detection is accomplished much like the hot-wire sensor, above, but in a capacitance bridge rather than a wheatstone bridge. The ~p~~ql type senses the change in refractive index between the liquid and vapor, which of course is closely related to the dielectric constant and density. This type of transducer contains a light source and a light sensitive cell which are isolated from one another but which do conmriunicate down a prism. The prism is cut in such a way as to have total internal reflection when in gas, and yet let the light escape when in liquid. This is possible since there is a difference in the index of refraction of the PAGENO="1321" 1315 liquid and the vapor, and since the critical angle for total internal reflection depends upon the index of refraction. This type of transducer has a very high in-out signal ratio, for the light detector is almost totally illuminated or not. There are also several acoustic or ultrasonic devices which depend upon the fact that the damping of the vibrating member is greater in the liquid than in the vapor. Often, a magnetostrictive element is driven at a constant power and is more or less dampened de- pending whether it is in liquid or in vapor. The end of these sensors is about the size of a quarter dollar, but this does not in any way indicate the limit of its resolution. These devices can be tuned to detect only a fraction of the total damping that would occur upon total immersion so that their sensitivity can be much smaller than the total end of the device. Piezoelectric versions of this acoustic type liquid level sensor are also available. 5.4.2 Continuous Liquid Level Sensors Figure 5.3 illustrates several types of continuous liquid level sensors. Shown schematically are: (a) a direct weighing scheme, (b) differential pressure, Cc) capacitance, (d) acoustic and (e) nuclear radiation attenuation. Direct weighing schemes have indeed been used for hydrogen, but have been handicapped by the fact that the weight of the container is often large compared to the weight of the contents. In modern weigh-facilities the weight of the tank rarely exceeds the weight of the contents (when the tank is full). Calibrated balance weights and strain-gage load cells are most commonly used in this application. Differential pressure measurements are simple to visualize, but difficult to realize for liquid hydrogen. The `signal" is low due to the very low density of hydrogen and the "noise" is high due to boiling and potential thermal oscillations at the lower pressure tap. Also, the unknown level of the liquid in the gage lines can introduce hydrostatic head errors. ē~pacitance sensors are widely used for the continuous measurement of the level of liquid hydrogen. They do not truly follow the interface but sense the total contents of the container. That is, the dielectric constant of the gas phase contributes to the output signal, as well as that of the liquid phase. This can be a serious source of error in hydrogen as the density of the cold gas (and hence its dielectric constant) is significant compared to that of the liquid. This problem is especially troublesome in nearly empty tanks, but is often compensated for by either: (a) segmenting the capacitor and ignoring the output from those sensor sections located in the vapor phase as the liquid level drops or (b) installing a few point sensors at critical levels and routinely calibrating the continuous sensor against them. Rod-to-blade and concentric tube configurations are most common in this type of sensor. In the acoustic device shown, the liquid itself is used as the transmitting medium. In this case, a transmitter feeds an electric pulse to a transducer where it is converted to an acoustic pulse traveling at sonic velocity to the liquid-vapor interface, reflected back at the same speed to the transducer, where it is reconverted to an electric pulse, 62-332 0 - 76 - 84 PAGENO="1322" [ GAS Output Signal Load Cell Capacitance Output Bridge Signal Plates ~~Capacitor LIQUID (c) GAS Measuring Sound Impulse Path LIQUID Output Calibration Sound Path Signal Sound Timing Transducers Circuit (d) Radiation /Output Detection Signal Radiation Source (e) 1316 Tare Weight (a) FIGURE 5.3 - Continuous Liquid Level Sensors. PAGENO="1323" 1317 and finally sent to a receiver. Knowing the velocity of sound in a given liquid, the pulse transit time from transmitter-to-interface-to-receiver becomes an indication of liquid level. In order to eliminate extraneous interfaces that may be caused by vapor bubbles in the liquid, a tubular still-well often is used to isolate the measured fluid column from such physical distrubances. Bubbles also may be suppressed by slight pressurization of the vessel immediately prior to any measurement. Sometimes an acoustic racetrack of known path length and variable time of flight is included to provide a measure of the density of the fluid. The product of the two measurements tends to give an indication of the mass of the fluid contained in the tank. Nuclear Radiation Attenuation (NRA) has found some success in oxygen and nitrogen systems, but comparatively little use for hydrogen. This is so because hydrogen is nearly transparent to th~ commonly available sources of nuclear radiation, while the tank walls are relatively "thick to the same radiation. Hence the fundamental signal to noise ratio is inherently low. Hydrogen does absorb beta radiation rather well, but then "windows" of beryllium or equivalent light metals must be placed in the tank walls. On the whole, this technique seems too sophisticated for simple engineering measurements. Not shown, because the system consists of inserting a simple dipole antenna into the tank, is RF cavity detection. In this system microwave energy is introduced into a tank so as to energize it by setting up electromagnetic fields throughout the entire volume of the tank. The tank interior is a dielectric region completely surrounded by conducting walls. Such a system is called a cavity, and the resonant frequencies established are the normal theoretical modes of the cavity. Considerable development work has been done very recently on both uniform density fluids, and non-uniform density fluids and this technique continues to show considerable promise for both mass-gaging and level-gaging in a variety of cryogenic fluids, including hydrogen. JtF transmission characteristics through coaxial cables can also be used to detect liquid levels by measuring the time of flight of a RF pulse through the cable [4,5]. This latter technique is called time domain reflectometry (TDR). Heated platinum wires or ribbons have been used as continuous liquid level sensors in cryogenic fluids but have found little application in hydrogen service. With continuing improvements in superconducting materials it may soon be possible to use a superconducting wire to detect liquid level in hydrogen containers -- in the absence of magnetic fields, materials already exist that are suitable for operation up to 23 K. 5.4.3 Liquid Level Summary Extensive development of liquid hydrogen level detectors took place during the space program, but it is remarkable how little space hardware is actually used in the commer- cial sector. A deliberate effort to adapt space instrumentation to commercial and industrial application seems worthwhile. Primary instruments and facilities to calibrate liquid level devices do not exist. Unlike pressure or temperature measurements, this part of the national measurement system is chaotic and needs to be brought under control. PAGENO="1324" 1318 5.5 DENSITY Density measurements are closely akin to liquid level measurements because: 1) both are often required simultaneously to establish the mass contents of a tank, and 2) the sane physical principle may often be used for either measurement, since, as noted, liquid level detectors sense the steep density gradient at the liquid-vapor interface. Thus, the methods of density determination include the following techniques: direct weighing, buoyancy, differential pressure, capacitance, optical, acoustic, ultrasonic, momentum, rotating paddle, transverse momentum and nuclear radiation attenuation. Each of the principles involved will be discussed along with its relative merits and shortcomings. 5.5.1 Direct Weighing Method The direct weighing method of density determination measures the volume and weight of the mixture to obtain density. Although direct weighing is not considered a field-type instrument, it could serve as a primary calibration standard. Some of the advantages of this method are the simplicity of the equipment, repeatability, good frequency response, and the lack of dependence of pressure, temperature, and fluid inhomogeneities on the ~easurement. A disadvantage of direct weighing is the poor sensitivity, due to the fact that the entire system must be weighed or nulled out. 5.5.2 Buoyant Force Method Density of a fluid may be measured by the buoyant force of the fluid upon a sub- merged plummet. This method is ideally suited for static laboratory use and involves relatively simple equipment. The drawbacks of the buoyancy method are slow response, poor sensitivity, and the need to make a remote reading of a mechanical displacement. 5.5.3 Differential Pressure Method The differential pressure method measures the pressure of a vertical column of the fluid which, along with the height of the column, gives the density. Advantages of this method are: relatively simple equipment, small component size, and the possibility of application as a field type instrument. This method has several disadvantages. The method is dependent upon two separate measurements, pressure differential and fluid liquid level. Errors in the accuracy of either of these two separate measurements will affect the over-all method accuracy. Be- cause of the extreme low density of liquid hydrogen, the accuracy, the sensitivity, and the hysteresis of the differential pressure measurement will be adversely affected. This method also requires a sophisticated electronic system to compute the average fluid density. 5.5.4 Capacitance Method The determination of density through capacitance measurements depends upon the fact that the dielectric constant and density are related for simple fluids, such as hydrogen, by the well-known Clausius-Nossotti function: P = 1(0 - 1)/Cc + 2)](l/p). Where P is the macroscopic polarizability in units of induced dipole moment per unit mass per unft applied field, and c and p are the dielectric constant and density in cgs units. PAGENO="1325" 1319 Thus, a measure of the dielectric constant (capacitance measurement) is a direct measurement of the density. Disadvantages include the well known problems of making good capacitance measurements in the field without stray signals and erroneous temperature effects. 5.5.5 Optical Method The optical method utilizes the relationship of spectral absorption to fluid density. The density of hydrogen can be measured by measuring the amount of spectral absorption, caused by the fluid, of an incident light source. 1 ln where: p = density of fluid u = absorption coefficient S = light path length I = measured intensity after passing through length I = incident intensity. Using the infra-red spectrum, this method can determine the density of liquid hydrogen because a number of spectral absorption lines exist in the range of 4100 to 5100 wave numbers for these fluids. Such a method should have good frequency response, adequate sensitivity, and not be restricted to homogeneous fluids. However, the problem of pro- viding optical windows may be overwhelming. 5.5.6 Acoustic Method The acoustic method utilizes the fact that the velocity of propagation of a sound wave in a fluid is directly related to the fluid density: c-~'W where: c = velocity of propagation of a sound wave K - bulk modulus, a constant for a particular fluid p = density of the fluid Solving the above equation for the fluid density yields: p - K/c2, or p - Kt2/62, where = distance between the sound wave transmitter and the sound wave receiver, and = time required for the sound wave to travel distance S. Thus, fluid density is measured by measuring the time required for the sound wave to travel from the sound wave transmitter, through the fluid, to the sound wave receiver. PAGENO="1326" 1320 This method has been used for both static and dynamic fluid density measurements with some success. Advantages of this method include a good frequency response and the fact that there are no moving parts located in the fluid. This method has several disadvantages such as a low signal to noise ratio, the fact that fluid turbulence and fluid non-homogeneity will cause spurious echoes, and a bulky Instrument is required. Also, temperature effects that influence the fluid vessel geometry may adversely affect performance. 5.5.7 Ultrasonic Method Ike ultrasonic method measures the impedance of a crystal vibrating in a fluid; this im;udance can be related to the fluids density. For instance, a piezoelectric crystal, in torcional vibration, immersed in a fluid, has its electrical impedance related to the fluid density by: n 2 (K1R - K2R0)2 p=i- (~) -ii p density of the fluid f0 = resonant frequency m/s = mass to surface ratio R = impedance of the crystal at its natural frequency R = impedance of the crystal at its natural frequency in a vacuum a = viscosity of fluid The terms K1 and K., may be considered constant over a small fluid viscosity range. For density measurements where the fluid viscosity range is appreciable, a more general equation is applicable: (tsf - M )2 m m2 total o P~f s i = bandwidth at the half power point .lf = bandwidth at the half power point in a vacuum For most density measuring applications the fluid viscosity range is not too great, therefore the first equation is applicable. to this case, sufficient accuracy is generally teltieved solely by measuring the impedance R and neglecting the term R. With this, fluid density is related to impedance by: p ~ R2. This ultrasonic method of density measurement has advantages that include excellent frequency response and sensitivity. Disadvantages of this method include the delicate nature of the apparatus, the requirement of a quiescent fluid medium, and the vis Osity dep°ndence. PAGENO="1327" 1321 5.5.8 Momentum Methods Density can be measured by several momentum methods. The density of the fluid is obtained by measuring fluid flow rate and fluid flow momentum. For instance, the rotating paddle method is based on the principle that an aerodynamic foil, if rotated through a fluid, will experience a measurable drag which can be related to density. The rotating paddle serves a two-fold purpose: density measurement and stirring of the mixture. The equipment required is relatively simple. Disadvantages include low frequency response and sensitivity, and the presence of moving parts in the fluid. Density of a fluid can also be measured by the angular momentum method, which measures the angular momentum of a rotating fluid and relates this momentum to density. As in the rotating paddle method, the angular momentum method measures the density and stirs the mixture. The equipment required is relatively simple. Disadvantages of this method include the presence, of bulky, moving parts in the fluid and the lack of any known investi- gation into the method's applicability to a static fluid density measurement. One particular hydrogen momentum densitometer depends upon the fact that the mass of any vibrating system is a primary factor in determining the dynamic characteristics of the system. If the system is designed so that the fluid flowing through it measurably affects the vibrating mass, a means of measuring fluid densities will have been provided. The dynamometer, sensing the force exerted by passage of the fluid, generates a signal, (E), in phase with the motion and proportional to the maximum force, or: E `~F sinOlt ac max f If Eac is rectified, the resulting signal; (Ed), is proportional to the maximum force, or: Ed'~~F. The final relation for the fluid density takes the form: .p=a+b' Edc where: a and b' are experimental constants. This method will, hence, determine fluid density with the fluid in either a static or dynamic condition. Advantages of this method are in its frequency response, repeatability, and linearity. This method also has advantages of being unaffected by fluid pressure effects, is not dependent upon fluid homogeneity, ~nd can be made fluid-material compatible. This type of densitometer has been evaluated in oxygen and nitrogen systems but application to liquid hydrogen will require higher sensitivities. PAGENO="1328" 1322 5.5.9 Nuclear Radiation Method The nuclear radiation method utilizes the adsorption of radiation energy by the fluid medium interposed between a radiation source and a radiation detector. Typically, this method for hydrogen employs a beta or low energy gamma radiation source so focused to impinge on the radiation detector placed on the opposite side of the fluid container. The fluid may be in eIther a static or a dynamic condition. The adsorption of a collimated radiation beam from the radiation source in the matter interposed between the radiation source and the radiation detector is given by: I = I exp (-VT) I = intensity at receiver I = intensity of source - V = linear adsorption coefficient T thickness of the adsorber. V, the linear adsorption coefficient, is related to the density of the matter inter- posed between the source and detector by the expression: V - where p is the apparent or combined density of the matter interposed between the source and detector. In this case p is the combined density of the fluid container, p, and the fluid, Pf. 0 is the mass adsorption coefficient which for a particular fluid and con- tainer is a constant. The fundamental adsorption equation may now be written in the form: I = I exp (-KPf) I = I exp (-p Tc Oc) K = 0~ For a fluid container having a fixed geometry, the intensity of radiation received by the detecter is related to the density of the fluid inside the container by: dl = - K Pf. Ihus, a linear change in fluid density causes a linear change in output signal. This method has a distinct advantage in the fact that no moving parts are inside the fluid container. This method can be highly repeatable, and have little hysteresis error. PAGENO="1329" 1323 Primary disadvantages, besides those inherent to any radiation measurement include the need for windows transparent to the radiation (or long counting times) and the need for a fairly long adsorption path. 5.5.10 Density Summary Density is an inferential measurement, and as such, It should be traceable to a national standard, such as a national density reference system. Primary instruments to calibrate iensitometers do not exist. Several physical principles of hydrogen density measurement have been brought well torward by the space program. Notable are the capacitance, vibration, and nuclear radiation attenuation schemes. Microwave methods (see Section 5.4.2) are recently moving to the Fore- front. It is felt that the pressing need now is to: a) commercialize these instruments routine engineering applications and b) provide an adequate national reference system. 5.6 FLOW There are three basic types of flowmeters which are useful for liquid hydrogen. Itiese crc the i) pressure drop or `head' type, 2) the turbine type, and (3) the mooest:im type. he sliail discuss each in turn. 5.6.1 Head Meters This type of meter embodies the oldest method of measuring flowing fluids. The dis- tinctive feature of head meters is that a restriction is employed to cause a reduction in the static pressure of the flowing fluid. This pressure change is measured as the difference between the static heads on the upstream and downstream sides of the restriction. Theoretical development of the flow equations for head type meters may be found in pablications of the ASME [6~. A simple expansion of Bernouilli's theorem leads to an equation of the form: v V is the velocity, p the density, g the gravitational constant and ~lP the pressure dcop The 1orm of the solution is independent of the particular embodice,:t of the flow restriction, whether it be an orifice plate, venturi, or flow nozzle. The appeal of these meters in cryogenics is more than simplicity and sterrc from the possibility of eliminating the necessity for calibration, if proper design, application theory and practices are followed. Design methods for orifices, flow nozzles, and senturt tubes are available in publications of the ASME [6]. Recommended practice for flange- :entod sharp-edge orifice plates can be found in publications of the ISA [7] and ISO 1~1. PAGENO="1330" 1324 These recotanendations which were developed for water can be corrected for thermal contrac- tion of the flow device and used to provide suitable flow measurements at cryogenic tempera- tures. Reynolds number increases caused by the low viscosity of cryogens are treated in the conventional way, i.e., by adjustment of the head meter discharge coefficient. The characteristics of this class of meter are as follows. The device is strictly a volumetric meter, that is, it can of itself give no information regarding mass flow rate. With appropriate pressure sensing, the range can be extended up to 10 to 1. It is the very nature of these devices that they generate a decrease in pressure by accelerating the fluid. If we are dealing with a saturated cryogen, then this sudden decrease in pressure could lead to vapor formation (cavitation) in the flowing stream and an erroneous flow measurement. Richards et al. [9] addressed themselves to the problem of potential cavitation in head meters designed for cryogenic flow. Richards made many attempts to obtain points off the calibration curve with the upstream static pressure lower than the equilibrium vapor pressure. In spite of the fact that the downstream static pressure was as much as 10 inches of mercury below the vapor pressure, all of the points fell on the calibration curve. within the accuracy of the experiments. Although these particular experiments showed no ill-effects attributable to cavitation, it is good design practice to maintain static liquid pressures within the meter well above the fluid saturation pressure. In spite of all shortcomings, head meters are widely used and quite reliable. 5.6.2 Turbine Type Meters The turbine-type volumetric flowmeter is probably the most popular of the various flow-measuring instruments. This is partially due to a lack of direct mass-measuring flowmeters, although the simple mechanical design and the demonstrated repeatability are sufficient merits of their own. The turbine-type volumetric flowmeter is a simple mechanism which consists of a freely spinning rotor having N blades, each inclined at an angle a to the axis of flow. The rotor is supported in guides or bearings mounted in a housing which forms a section of the pipeline. The angular velocity (rpm) of the rotor may be detected by one of a number of methods; e.g., a permanent magnet encased in a rotor body will induce an alternating voltage in an induc- tive pickup coil mounted on the housing, or the core of the pickup coil may consist of a permanent magnet and the rotor constructed of a magnetic material so that the change in magnetic circuit reluctance, as each rotor blade passes the coil core, causes an alternating current to be induced in the coil. Capacitive and photoelectric methods of observing rotor rpm have also been used. The primary requirement, however, is that the angular velocity of the rotor be directly proportional to volumetric flowrate, or more correctly, to some average velocity of the fluid in the pipe. A mathematical description of the turbine-type flowmeter is given by Vtano Q tana R - A7-A R PAGENO="1331" 1325 where w is the rotor angular velocity, V is the average flow velocity at the rotor blades, a is the rotor blade angle with the pipe axis, R is the average radius of rotor blade center of pressure, Q is the volumetric flow rate, A~ is the internal cross-sectional area of housing, and A is the maximum cross-sectional area of rotor. r Deviations from, this idealized mathematical expression can be expected because of (1) retarding forces on the rotor such as fluid drag, mechanical friction from rotary and thrust bearings, and transducer magnetic drag, (2) velocity profile variations, and (3) swirl of the incoming fluid stream. A variation of the turbine type meter is the "twin turbine" type. In this case, two turbines of different blade pitch are coupled together by means of an elastic restraint. Because of the difference in pitch, they would tend to revolve at different speeds. How- ever, this is prevented by the elastic coupling, so that they do revolve at the same speed, but with a "phase angle" between them. The magnitude of the phase angle is a measure of the flow rate, and is said to be, in fact, a measure of the mass flow rate. The turbine type flowmeter is widely used for several reasons. It is, first of all, a simple mechanism. It generally is of a minimum physical size, therefore it is light- weight. This means a minimum mass to cool. It has a flow range of 10 to 1. The electrical signal output is easily converted to digital, hence readily adaptable to telemetry systems. It is self-propelled (fluid flow supplies the driving force) and no electric driving motors are required. In case of bearing failure, which could jam the rotor, no further impedance to flow results. There are no shaft or electrical seals required between the fluid and the meter exterior. It has a record of good repeatability, and the meter has had extensive use. While the turbine-type flowmeter has the above advantages, there are certain consi- derations which must be made when using the flowmeter in hydrogen service. For instance, turbine meters can be damaged by excessive rotor speed from gasseous or two-phase flow. As with some other meters with moving elements, protection must be provided through proper piping design, venting, bleeding and cooldown procedures. Screens are sometimes installed in the pipeline downstream of these meters to collect turbine blades in the event of an overspin failure. Such screens are good insurance against damage to expensive pumping equipment, etc. that may be located downstream of the turbine meter. Other considerations governing turbine meters are: thermal effects which may cause dimensional changes of the rotor blade and hence rotor speed; and change in the average velocity profile due to changes in fluid viscosity [10]. Also, there is some pressure drop across these meters and they are subject to cavitation-induced errors as are the head meters. To achieve the full potential of the turbine meter as a flow measurement element in cryogenics, the meter must be calibrated at the cryogenic temperature and with the fluid intended for use. 5.6.3 Vortex Shedding Meter The vortex shedding meter is also a single-phase fluid rate-velocity meter, like the turbine meters, but in a distinct class by itself. PAGENO="1332" 1326 The phenomena upon which it is based is the Karman vortex trail and its application to the measurement of flow of liquids and gases is fairly recent [11), probably because only recently have sensors become available to detect the vortices. The Karman vortex trail is used to explain certain phenomena associated with the flow around cylinders, ellipsoids, and flat plates. For flow around a cylinder, for instance, at Reynold's numbers above about 20, eddy's break off alternately on either side in a periodic fashion. Behind the cylinder is a staggered, stable arrangement or trail of vortices. The alternate shedding produces a periodic force acting on the cylinder normal to the undisturbed flow. The force acts first in one direction and then in the opposite direction. Let f represent the frequency of this vibration in cycles per unit time, 0 the diameter of the cylinder and V the undisturbed velocity. Experiments have shown values of the dimensionless Strouhal Number, fD/V, to vary between 0.13 and 0.27. If the frequency of the vortex peeling approaches or equals the natural frequency of the elastic system consisting of the cylinder and its supports, the cylinder may have a small alternating displacement normal to the stream flow. (The vibration of some smoke stacks, the vibration of some transmission lines, and the fatigue failure or progressive fracture of some transmission lines have been attributed to this resonance phenomenon). - Such a meter was evaluated on liquid nitrogen at NBS [12]. It consisted of a bluff body located normal to the flow stream and basically measured the average velocity of the flow passing through the pipe. The frequency f of the vortex shedding was given approxi- mately by = 0.27 V Hz where V is the velocity in feet per second and 0 is the nominal meter diameter in feet. The bluff body was in the shape of a modified delta with its base facing upstream. The vortex sensors consist of electronically self heated resistance elements whose temperatures and therefore resistances vary as a result of the velocity variations adjacent to the body. These velocity variations reflect directly the action of the vortices as they peel off from the downstream edge of the bluff body. The precision of this meter was quite good (approximately 1/2 percent, 3a), but the range of linearity was found to be about 5 to 1 rather than the expected 10 to 1. Since these meters are quite new to cryogenic service, one can reasonably hope their performance to improve with further experience. They have the advantage of no moving parts at the low temperatures and therefore require minimum maintenance. The meter factor (pulses/gallon) depends only on the inside diameter of the pipe and the width across the bluff body face. Cryogenic evaluation is limited, but performance on liquid nitrogen and oxygen shows promise. 5.6.4 Momentum Mass Flowmeters Mass reaction or momentum flowmeters are of three types. There are those in which an impeller imparts a constant angular momentum to the fluid stream and then the variable torque on a turbine which removes this momentum is measured; there are those in which an PAGENO="1333" 1327 impeller is driven at a constant torque and then the variable angular velocity of the impeller is measured; and those in which a loop of fluid is driven at either a constant angular speed or a constant oscillatory motion and then the mass reaction measured. One type of mass reaction flowmeter is shown in Fig. 5.4. The cylindrical impeller and turbine are coaxially mounted in the fluid conduit, but each on a separate shaft. The axial vaned impeller imparts a constant angular momentum to the fluid while the axial vaned turbine removes the angular momentum. A measure of the torque on the turbine, which is elastically restrained, is a measure of the mass flow rate. This flowmeter employs rotating elements in the fluid stream. Some consider the use of such rotating elements in a cryogenic fluid stream a disadvantage since they are subject to mechanical failure. Ex- perience has shown however that the probability of such a failure is quite remote. Another type of these mass reaction flowmeters is shown in Fig. 5.5. A single axial vaned impeller is used in conjunction with a hysteresis drive and an exterior mounted drive motor. Torque is maintained constant and the impeller speed is varied inversely with the mass flow rate. A measure of the impeller speed is a measure of the mass flow rate. This scheme has the characteristics of high resolution at low flow rates and decreasing resolu- tion as the flow rate increases. This flowmeter also employs a rotating element in the fluid stream. The previous remarks concerning moving elements in a cryogenic fluid stream apply here also. Still another type of mass reaction flowmeter is shown in Fig. 5.6. This flowmeter consists of a closed loop through which the fluid flows, a means of driving the closed loop in a constant manner, and a means of measuring the mass reaction. Instead of rotating the loop, as shown in Fig. 5.6, the loop is driven in an oscillating fashion, thus the mea- sured mass reaction has an oscillating value. This oscillation of the loop eliminates the need for rotating seals. While this flowmeter does not employ moving parts that are located in the fluid stream, it does require a mechanical movement of the flow loop itself which some consider a disadvantage. The above described mass reaction flowmeters have in common the fact that momentum must be imparted to the fluid stream and require that the mass reaction due to this momentum be measured to determine the mass flow rate. The performance of these flowmeters were determined in a NASA sponsored flowmeter evaluation program [13]. From the results of this program it appears that several cryogenic mass flowmeters have been developed that are capable of liquid hydrogen mass flow measurement accuracies on the order of ± 0.5 percent. There appears to be degradation of mass flow measurement accuracy however when subjected to a two-phase flow. There are several other concepts of cryogenic fluid flowmeters that are available or are in development. Since they were not evaluated in the previously mentioned NASA-sponsored program, definitive performance results, on the scale of the previously discussed mass flow- meters, are not yet available. These flowmeters are inferential mass flow measurement devices having in common measurements of fluid density and fluid volume flow or fluid volume flow-induced momentum. PAGENO="1334" 1328 FIGURE 5.4 - Axial Flow Transverse Momentum Mass Flowmeter. FLOW PICKUP COIL ROTOR SHAFT ASSEMBLY /HYSTERESIS / DRIVE I~1~~II~MOTOR FLOW STRAIGHTE FIGURE 5.5 - Axial Flow Transverse Momentum Mass Flowmeter. Y DISC 11 STATIONARY FIGURE 5.6 - Gyroscopic Transverse Momentum Mass Flowmeter. PAGENO="1335" 1329 5.6.5 Flowmeter Summary There is no shortage of physical principles upon which to base a hydrogen flowmeter. Depending on the need, they range from simple pressure-drop meters to sophisticated mass reaction meters. The need is thus not for more types of meters, but rather stems from the problem common to every type. Namely, flow is a derived, not an intrinsic, quantity. As such, every flowmeter will require traceability to a reference system to establish its credibi- lity. The general needs were perhaps best articulated in four categories by Mann [14]: 1. Flow Reference Systems. A study should be initiated to identify those systems that are currently available to document the flow range, pressure and temperature capabili- ties, precision and accuracy relative to basic standards and multiple test fluid capability. After establishing location and capability, a system of interlaboratory comparisons should be initiated by exchange of test meters and performance data for these test meters as ob- tained on each reference system. This interlaboratory comparison using reference test meters would identify systematic errors existing with respect to individual facilities relative to the entire reference measurement system. 2. Substitute Fluids. A concerted program should be inititated and designed to determine the appropriateness of the use of substitute fluids for cryogenic flow metering calibrations. This would include a program designed to determine the reasons for water calibration errors experienced at cryogenic temperatures as well as experimental evidence that other fluids (such as liquid nitrogen) may be used as a test fluid in place of liquid hydrogen. 3. Large Flow. General purpose flow reference systems are at the present time restricted to less than 200-300 gallons per minute. The trend for flow measurement is to higher and higher flow rates in excess of these values. The severity of modern constraints placed on design and operation and the requirements both economical and technological for mass flow measurements to total uncertainties of less than one percent, suggest that a fresh look be taken at establishing a general purpose cryogenic flow research center. Such a center would include as process fluids: water, liquid oxygen, liquid methane, liquid nitrogen, liquid argon, and liquid hydrogen. Flow range should extend to 3.8 m3/s (60,000 gpm) with provision for pressure and temperature controls. A cryogenic flow research center of this size and scope would impact on present oxygen and hydrogen aerospace requirements, short term (10-20 year) energy importation programs (LNG), and long term requirements of a hydrogen-based energy system. The latter has tre- mendous potential in providing and distributing energy in an environmentally attractive form using many existing fossil fuel type systems, but will require high density liquid storage systems to make it a workable concept in certain cases. 4. Uniform Performance Method. Standard tests or codes should be developed and adopted where possible for cryogenic flow measurement. The number of experimental points, treatment of experimental data and reporting of error should be standardized to provide common and effective criteria for meter evaluation. In short, this branch of the National Measurement System needs to be brought under con- trol, and such a program of quality assurance would have far ranging benefits, extending greatly beyond only hydrogen technology itself. PAGENO="1336" 1330 5.7 REFERENCES [1] Dean, J. W., and Flynn, T. H., Temperature Effects on Pressure Transducers, ISA Transaction 5, 223-232 (1966). 12] Arvidson, 3. H., and Brennan, 3. A., Pressure Measurement, ASRDI Technology Survey, (to be published). [3] Measurements and Data 7, No. 2, 101-112 (Mar-Apr 1973). [4] Cruz, 3. E., Rogers, E. H., and Heister, A. E., Continuous Liquid Level Measurements with Time-Domain Reflectometry, Book, Advances in Cryogenic Engineering, 18, 323-327, (Ed.) K. D. Timmerhaus (Plenum Press, Inc., New York, N.Y., 1973). - [5] Willis, W. L., Disturbance of Capacitive Liquid Level Gauges by Nuclear Radiation, Book, Advances in Cryogenic Engineering, 12, 666-672, (Ed.) K. D. Timmerhaus (Plenum Press, Inc., New York, N.Y., 1967): See also, Willis, W. L., and Taylor, 3. F., Time Domain Reflectometry for Liquid Hydrogen Level Detection, lJnclass. Kept. LA-3474-MS, Los Alamos Scientific Laboratory, Los Alamos, New Mexico (Feb. 1966). [6] ASME, Fluid Meters, Their Theory and Applications, 6th Edition (ASME, New York, N.Y., 1971). [7] ISA, Standard Practices for Instrumentation, Instrument Society of America, Pittsburgh, PA. (l970)'~ [8] ISO Recommendation R-541, Measurement of Fluid Flow by Means of Orifice Plates and Nozzles (Jan. 1967). [9] Richards, R. 3., Jacobs, R. B., and Pestalozzi, W. J., Measurement of the Flow of Liquefied Gases with Sharp-edged Orifices, Book, Advances in Cryogenic Engineering, 4, 272-285 (Ed.) K. D. Ticmierhaus, (Plenum Press, Inc., New York, N.Y., 1960). [10] Grey, J., Journ. of ARS, 30, No. 2, 192 (Feb. 1960). [11] Rodeley, A. E., Vortex Shedding Flowmeter, Measurements and Data, No. 18, (Nov-Dec. 1969). [12] Brennan, J. A., Stokes, R. W., Kneebone, C. H., and Mann, D. B. * An Evaluation of Selected Angular Momentum, Vortex Shedding and Orifice Cryogenic Flowmeters, NBS Tech. Note No. 650 (Mar. 1974). 113) Wyle Laboratories, Final Report, Contract No. HAS 8-1526, Liquid Hydrogen Mass Flow- meter Evaluation, (Jan. 1965). [14] Mann, 13. B., ASRDI Oxygen Technology S~trvey, Flow Measurement Instrumentation, NASA SP-3084 (1974). [15] Corruccini, R. J., Tecperature Measurement in Cryogenic Engineering, Book, Advances in Cryogenic Engineering 8, 315-333, (Ed.) K. D. Tinmerhaus (Plenum Press, Inc., New York, N.Y., 1963). [16] Corruccini, K. J., Principles of Thermometry (Measurement of Temperature), Treatise on Analytical Chemistry, Part I, Volume 8, 4937-4990 (John Wiley and Sons, New York, N.Y., 1968). [17] Rubin, L. G., Cryogenic Thernometrv: A Reviev of Recent Progress, Cryogenics 10, No. 1, 14-22 (Feb., 1970). [18] Sinclair, 0. 11., Terbeek, H. G., and Malone, 3. H., Cryogenic Temperature Measurement, Cryogenic and Industrial Gases 5, No. 7, 15-22 (July-Aug. 1970). [19] Sparks, L. L., Low Temperature Measurement, ASRDI Oxygen Technology Survey, Volume IV, NASA SP-3073 (1974). (For Sale by the National Technical Information Service, Springfield, VA 22151, Price $3.75.) [20] Roder, H. M., ASRDI Oxygen Technology Survey, Volume V: Density and Liquid Level Mea- surement Instrumentation P or the Cryogenic Fluids Oxygen, Hydrogen and Nitrogen, NASA SP-3083 (1974). (For sale by the National Technical Information Service, Springfield, VA 22151, Price $3.75). PAGENO="1337" 1331 CHAPTER 6 TRANSMISSION OF HYDROGEN C. F. Sindt 6.0 SU9NARY Transmission and transport of hydrogen were studied to determine the most economical method of delivering liquid hydrogen. From economical considerations alone, hydrogen should not be liquefied for transmission or transport except when delivery is across more than 200 km of ocean or unless hydrogen is to be used as a liquid. In practice, hydrogen is frequently liquefied to facilitate transport, i.e., it is liquefied for convenience of transport and delivery. When the final use requires liquid hydrogen, it can be transmitted as gas or liquid, or the energy can be transmitted as electricity to produce hydrogen gas and to liquefy it at the final destination. Costs of transmission, production, and liquefaction must all be considered before the most economical method of delivering liquid hydrogen can be determined in any specific delivery system. For this study a 1200 MW electrical power plant was the assumed source of electrical power to produce hydrogen gas and to run the liquefier. Because the electrical power generation may occur some distance from the delivery terminal, liquid hydrogen transmission distances of 80 and 1600 km were used in this analysis. Costs of delivered liquid hydrogen were determined for the following energy transmission systems: gaseous hydrogen pipeline, liquid hydrogen pipeline, electrical power line, elec- trical power line combined with liquid or gas pipeline, truck and rail transport of liquid, and liquid transport by ocean tanker. The systems that combine electrical power lines and gas or liquid pipelines used the electricity to liquefy gas or to pump and refrigerate liquid in the pipeline. The costs of delivered liquid hydrogen varies with electrical power costs; hydrogen costs were calculated for electrical costs ranging from 5 to 45 mills/kW-h. For a transmission distance of 80 km and electricity costs of 12 mills/kW_he, the lowest delivered cost of liquid hydrogen was 19 mi1ls/kW_h~; the transmission system was the combined gas pipeline and electrical power line. For 1600 km distance and 12 mills/kW_he electricity costs, the lowest delivered cost of liquid hydrogen was 22 mills! kW_h~; the method of transport was ocean tanker. The lowest cost for hydrogen transmission over land was obtained with the combined gas pipeline-electrical power line system (23 mills/kW_h~). Truck and rail transport of liquid were more costly for both 80 and 1600 km distances, but they may be preferable because they accommodate widely separated delivery sites. 6.1 INTRODUCTION Transmission costs of hydrogen have been reported by others [1-31 and some comparisons have been made of costs to deliver hydrogen as liquid and gas. Gregory [1] has performed detailed cost analysis of hydrogen gas transmission. Johnson [2] compares costs of gas transmission and costs of transporting liquid in barges. He also gives some comparative costs of transporting liquid and costs of delivering liquid hydrogen produced from coal gasification and from nuclear power. From the data of Gregory and Johnson, it is apparent that hydrogen should not be liquefied for transport over land if the end use does not require liquid. We, therefore, did not analyze costs for delivering gaseous hydrogen but 62-332 0 - 76 - 85 PAGENO="1338" 1332 concentrated on cost analysis for delivering liquid hydrogen to those users who require hydrogen in liquid form. Transport or transmission costs alone do not reflect the total cost of delivery of liquid hydrogen. The complete system of production, liquefaction and transmission must be considered because of the significant differences in the energy consumed in the different systems. To obtain a comparison of the conventional methods of delivering liquid hydrogen, eight systems were analyzed using six methods of transmitting or trans- porting energy over two distances. To keep the comparison of the systems on an equal basis, it was assumed that a 1200 MW electrical power plant supplied energy to the systems, but no specific energy sources for the power plant were considered. Each system was then analyzed to determine the cost of delivering liquid to the user's storage dewar as a function of the cost of the electrical power. 6.2 SYSTEM DESCRIPTIONS The approach taken was that the hydrogen was to be produced by electrolysis using power generated by some large electrical power plant such as a nuclear or solar plant. Since solar power was considered, and sea-power plants are normally far at sea, the transmission distance of 1600 km (approximately 1000 miles) was used as well as 80 km (50 miles). The 80 km would be more typical for a nuclear plant. The systems were evaluated for both transmission distances to get relative costs for liquid at the destination. The systems considered were: (1) liquid hydrogen production at the power plant and liquid transmission in a vacuum-and-Perlite insulated pipe; (2) production of hydrogen gas at the power plant, gas pipeline transmission with parallel electric power transmission to run the liquefier at the destination; (3) production of gas at the power plant, gas pipeline transmisslon with gas used from the pipeline at the destination to produce the liquefier power requirements; (4) electric power transmission to the destination, gas produced by electrolysis and liquefied at the destination; (5) gas and liquid produced at the power plant with truck transport of liquid; (6) gas and liquid produced at the power plant with railroad transport of liquid; and (7) gas and liquid produced at the power plant with ocean tanker transport of liquid. The last two systems were not considered for the 80-km transmission because railcar turnaround is a problem for such short hauls and therefore does not compete with trucks, and for 80 km the large ocean tankers are not competitive with off-shore pipelines. The seven methods of trans- mission are depicted in figure 6.1. 6.3 SYSTEM ANALYSIS To evaluate the methods of transmission to deliver liquid hydrogen to the user, the integrated system, not just the transmission method, must be considered. The approach used was to assign a power plant size of 1200 MW and to then size the components to fit this power source. The first assumption was that the plant was devoted strictly to production of hydrogen liquid and that it operated at an average load factor of 90%. All equipment was sized to take 100% of the power plant output. The second consideration was that the cost of producing electricity varied depending on the power plant, fuel, location, etc. Since cost of power is a major item in all systems, the analysis was made for PAGENO="1339" 1333 System 1, Liquid Pipeline POWER PLANT LIQUEFIER 10" INSULATED PIPE STORAGE DEWAR ELECTROLYZER ~ POWER PLANT STORAGE DEWAR ~ POWER PLANT ELECTROLYZER 24' PIPE LIQUEFIER STORAGE DEWAR ~ POWER PLANT LIQUEFIER STORAGE DEWAR ELECTROLYZER Syste~~ 5, Truck Transport 12O~O gal TANK - 15 LOADS/DAY POWER PLANT LIQUEPER .v ELECTROLYZER gal TANK CUR ~. 5 CAR LOADS! DAY road Transport POWER PLANT LIQUEFER I I STORAGE DEWAR ELECTROLYZER ELECTROLYZER STORAGE DEWAR STORAGE DEWAR 0 Figure 6. 1 1-lydrogen supply systems. PAGENO="1340" 1334 electrical cost of 5 to 45 mills per kW-h. Cost of gas and power lines was taken from Gregory El] and the Federal Power Commission Report [4]. Other costs used for the study are given in Chapter 2. The cost of the liquid hydrogen transmission pipeline (system 1) was estimated as $490 per meter of length. The line size selected was 25 cm (10 inches) in diameter with 15-cm-thick insulation. Construction and installation costs were not available, as no such line of the length considered has been used; therefore, the cost of installation was con- sidered to be near those of a power line. These costs were used because the installation of the liquid line was aboveground to facilitate maintenance of vacuum and access for replacing sections. The aboveground installation costs include purchase and clearing of right-of-way, and construction of supports for the line. Although support structures would be much smaller than for power lines, they would be much more frequent. This was the rationale used to justify the relatively large installation cost for liquid hydrogen lines versus gas pipelines. The 80-km-long liquid hydrogen line was sized so that no pumping or refrigeration stations were required along the way. The liquid was pumped to 2.02 MPa pressure at the liquefier, then cooled enough so that normal boiling point liquid arrived at the end of the 80-km line. This required the 15-cm-thick insulation. The use of slush hydrogen was considered, but the constraint of delivering normal- boiling-point liquid was met without adding the slush-producing equipment. The selection of the line diameter was not optimized for minimum energy consumption, but was selected to keep the velocity reasonably low so that the pressure drop in 80 km could be met without excessive pumping pressures. A very detailed analysis would have included transfer line costs as a function of pipe diameter and pressure loss, and then balanced these costs with energy consumption for pumping and refrigeration. It was felt that this type of detailed analysis was not warranted unless this preliminary comparison of hydrogen transmission costs indicated that the liquid hydrogen pipeline was a good choice. For system 2 the gas transmission costs for a 24-inch (61 cm) pipe [1] were used with appropriate adjustments for total gas flow. For the 80-km line, the gas compressors were considered to be located at the power plant and to be driven electrically. The electrical power transmission costs ware taken from The Federal Power Coumission Report [4], adjusting for the relatively short distance. The electric power line must supply approxi- mately 244 MW, so the costs for a 230 kV line were used. Energy losses in the power line were negligibly small for this analysis. The gas pipeline for system 3 was nearly the same as for system 2, since the change in the required flow was not significant for cost evaluation. The big difference between systems 2 and 3 was the back conversion of hydrogen gas to produce electricity to run the liquefier. This conversion includes a significant loss of energy due to inefficiency. Because fuel cells are estimated to be about 50% efficient, a fuel cell was considered as the means of converting the hydrogen to electrical energy. PAGENO="1341" 1335 System 4 used a 500 kV power transmission line which is near peak efficiency at 1200 MW. Electrical losses were small but significant and so they were included. Data for trucking costs for system 5 were taken from Eifel 1 5] and from current charges for trucking of liquid hydrogen. The costs of trucking LNG given by Eifel [5] were thought to be valid for liquid hydrogen since equipment and regulations for hauling are very similar. Railroad costs from Eifel [5] were used for system 6 for the 1600 km transmission distance. The railroad and trucking costs were adjusted for inflation which has occurred since 1968. Ocean shipping costs for system 7 were taken from the current shipping contracts for LNG. These contracts include the cost of operation and of docking. For the 1600 km transmission of hydrogen, the systems are very similar to those for 80 km except refrigerators and pumps are required every 80 km for system 1, and in systems 2 and 3 compressor stations are required every 105 km. Of course, electrical losses were greater for the electrical transmission lines in systems 2 and 4. Another system similar to system 1, identified as system 1A, was also analyzed for *the 1600 km distance. This system, which is a liquid pipeline with a parallel electrical power line to supply power for the refrigerators and pumps, was considered when it became evident that system 2 outperformed system 3. In system 1A a large portion of the power is required to run the refrigerators and pumps so that the delivered energy is still low but It is greater than system 1: In system 1 the inefficiency of converting the hydrogen back to mechanical power to run the refrigerators and pumps is very significant and reduces the delivered energy by a considerable amount. For systems 5, 6, and 7, the gas produced during cooldown of the transport tanks was recycled through the liquefier. The liquid vaporized at delivery by transfer losses and cooldown of the receiving hardware ~ considered lost from the liquid system; in practice, an effort would be made to recover this gas. The costs computed were costs of p'-oduction (not selling costs) and consider the total cost of capital, including interest, insurance, etc. to be 15 percent. Also, the costs are only representative of actual costs for average installations. Actual costs vary considerably; for instance las line and power line costs may vary as much as 300% due to the area of installation. 6.4 RESULTS The condensed results of the analysis are presented in table 6.1. System 2 is the least expensive means of supplying the liquid on shore for both distances considered. It is evident from the table that the systems delivering the most energy per year are also those that deliver liquid hydrogen at the lowest cost. The largest single cost item for most of the systems is the cost of electrical power and all of the systems were limited to the same amount of electrical power. Thus, delivered energy is representative of overall system efficiency. For the 80 km transmission, liquid piping (system 1) and total electrical power transmission (system 4) are competitive. The total gas pipeline transmission of system 3 suffers from the inefficiency of back converting gas to mechanical power to drive the PAGENO="1342" Table 6.1 Costs of Delivering Liquid Hydrogen 80 km and 1600 km from Power Plant. Electric Power (All Systems Use 1200 MW 8 Cost of 12 mills/kW-h5) (Costs are mills per unit of delivered energy based on the high heat value) TH I~'I 7~T ~` ) li~ 2. P~,~1221 22$ 21850 11.04 1.14 21850 2.25 1.19 fl 9.10 2 70 .53, 3,01 23.2 5.7 10' 5. T~,6k 7~'~o~p3st 22100 6. 4473402d u~ T7o4p~'1 2218)) 35.14 15.14 1.37 3.33 24470 24470 4.21 .74 4.23 1,74 ~ -- - -~ 0020) 1.43 `2155 5.26 --~-~- 14.7 23.7 .~-- 0.0 30' 5.7 12' ~-.- 4373: 3h~ h)gh4l 6441 ,~)f4 (82)4) fl o~,d 53d7'foo' `. ?.37 2953(2 10.47 39.6,904) PAGENO="1343" 1337 liquefier. Even though trucking (system 5) appears costly, it may be highly favored because of the flexibility of delivery locations and because no new technology is required (such as development of fuel cells and large hydrogen compressors for gas pipelines). Also, the liquid transfer losses of the truck system at delivery may be reduced below present day losses by improved procedures and hardware. The transfer losses at delivery were con- sidered an entire loss from the system. In actual practice, this gas would very likely be sold or used locally. This same argument holds true for the truck, railroad and ocean tanker systems for the 1600 km distance. For the 1600 km distance, the railroad system (system 6) is third lowest in cost; however, with improved transfer systems and use of boiloff gas, it could be more competitive with the gas-electric system (system 2). The railroad system does not require new technology. Since the cost of electrical power generation varies significantly with location, method of generation, cost of fuel, etc., the costa of producing and delivering liquid hydrogen were determined for power costs ranging from 5 to 45 mills per kW-h. These costs are shown in figures 6.2 and 6.3. For the 80 km distance, the truck transmission seems to increase at a higher rate than systems 1, 2, and 4; therefore, trucking may not be a good compromise if power coats are relatively high. For 1600 km distance, railroad costs remain second to system 2 for the range of electrical power costs and may be a good compromise. System lA, using liquid transmission and a parallel electric power line, still is not competitive because of the high costs of the insulated pipeline and the high capital and operating costs of refrigerators stationed every 80 km. The most economical means of moving very large quantities of liquid is by ocean tanker if the source and use points are seaports. A separate analysis was made to compare the system of transmission of hydrogen gas via offshore high pressure pipeline to the system of liquefaction and ocean tanker ship- ment. The cost for long distance offshore pipelines was estimated from one such line that is to be constructed at a projected cost of 3.1 x 106 s/km. Using this cost, a distance of 1600 km, a cost of 12 mills/kW_he for electricity, and current shipping costs for LNG, the ocean tanker shipping of liquid hydrogen was found to be less expensive than piping gas for delivery of hydrogen in either liquid or gaseous state to a seaport. 6.5 CONCLUSIONS As long as electrical power costs are below 15 mills/kW-h , the most practical means of supplying liquid hydrogen to users within about 100 km of the power plant is probably by truck. This method offers more versatility in that trucks can deliver to many different users. If the use is at a single installation, such as an airport, the gas pipeline with a parallel power line to run the liquefier is probably the best choice. This system has the added advantage of placing the liquefier so that any boiloff gases from storage, from transfer, and from detanking operations can be recovered and reliquefied. If the transmission distance is long, 1000 to 2000 km, the railroad delivery is attrac- tive. As for the short haul trucking case, it is more versatile in delivery, since two or more large and widely separated users can be supplied with very little additional cost. If PAGENO="1344" 100 -- 80 C ~ 60 - LU ~ 40 - V) L) 20 - 0 5 10 15 20 25 COST OF EI.ECTRrCIO. PflWER ~1iYkW-h System 3, Gas PipelineS System 5, System 1, Liquid I I I stem 4, Electric Powerline -tem 2, Parallel Gas and Electric Lines 30 35 40 6.2 ~ ~ i~d;ocien :HV~ ~t ~3 rn From ~HV=r~iih Hm~ Value. PAGENO="1345" 200 180 3.) -c ~ 160 (1) 140 C, u 120 0 0 >- ~ 100 0 ~8O 0 `- 60 C,, 0 220 System i, Liquid Pipeli System 1A, Liquid Pipeline & Parallel Electric Li 5 10 item 6, Railroad Transport COST OF ELECTRICAL POWER ~ FIGURE 6.3 Cost of Liquid Hydrogen (HHV) at 1600 km From Power Plant. HHV=High Heat Value. PAGENO="1346" 1340 all use is confined to a single airport or all users are close to a large storage dewar, the gas pipeline with the parallel electric power line looks to be most efficient and practical; again, the liquefier is located so that boiloff gas from heat leak and liquid transfer can be reliquefied. For hydrogen transmission across the ocean, liquefying and shipping is the most attractive. PAGENO="1347" 1341 6.6 REFERENCES [1] Gregory, D. P., A Hydrogen-Energy System, American Gas Association, Catalogue No. L21173 (1972). [21 Johnson, J. E., The Economics of Liquid Hydrogen for Air Transportation, Book, Advances in Cryogenic Engineering 19, (Ed.) K. D. Timmerhaus, p. 12-22 (Plenum Press, Inc., New York, N.Y., 1974). [3] Johnson, J. E., The Storage and Transportation of Synthetic Fuels, Report for the Synthetic Fuels Panel, ORNL-TM-4307 (1973). [4] The Federal Power Commission, The 1970 National Power Survey, U.S. Government Printing Office (1971). [5] Eifel, P. J., Comparative Costs of LNG Surface Transport, Gas Age 10, 20-23, (October 1968). PAGENO="1348" 1342 CHAPTER 7 SOLAR ENERGY--LIQUID HYDROGEN C. F. Sindt 7.0 SUMMARY Using a solar collector area of about 110 m2, year-round single-household energy needs in Boulder, Colorado, can be provided if the excess energy collected in summer is converted to and stored as liquid hydrogen for use in the winter; all space heating, hot water, and electricity needs can be supplied. The system to collect the energy, produce the hydrogen, and store it as liquid is complex: therefore, to be economical, it must be large enough to serve a community of 100 or more households. Ten major components are needed for the system; however, all except the solar collector and hydrogen-air fuel cell are commercially available. The solar energy-liquid hydrogen system discussed herein has some advantages over more conventional solar energy systems. Several of these advantages are: (1) the system has redundancy for supplying energy for space heating, hot water, and electricity, so it will provide the required reliability for utilities; (2) the system is self-contained and does not depend on energy sources external to the system during normal operation; and (3) if the solar collector does fail, emergency energy can be supplied from an external source in the form of liquid hydrogen. Cost of energy delivered by the system will very likely be competitive with other energy sources in the future. At solar collector costs of $30 per square meter, the energy costs are about 1.5 times present electricity costs and at $20 per square meter, the energy costs are about twice present energy costs for a Boulder home using propane and electricity. 7.1 INTRODUCTION In the northern half of the United States, the greatest part of the insolation occurs nearly six months out of phase from the greatest need for energy. To make solar energy a practical year-round total energy source in these regions, long term storage of this energy must be accomplished i0 a method compatible with other energy sources and compatible with community development. A preliminary study indicates that sufficient solar energy can be collected in some areas of the United States (such as the Missouri Valley, the Rocky Mountains, and the Southwest region) to supply all of the residential energy needs of the average household using 110 to 150 m2 of solar collector per residence. A solar system will provide the energy f or space heating, hot water, and electricity. To provide all three, the system must store summer energy for winter use. The excess summer energy is stored as chemical energy in the form of liquid hydrogen. The liquid is burned in the winter to make up the energy deficiency which occurs because of the low winter insolation. The solar energy-liquid hydrogen system is complex and is not economically feasible as a single resident unit. It is more suited as a public utility supplying a minimum PAGENO="1349" 1343 of approximately 100 residences or an apartment complex of 100 households per energy plant. Because energy for space heating must be distributed as a hot fluid--to keep heating effi- ciency high--the more condensed the coimsunity the less energy lost to pumping, heat transfer, "t.c. Energy systems to supply 100 average households were analyzed. 7.2 SYSTEM DESCRIPTIONS Two solar energy systems were evaluated for comparison. One system stores energy as liquid hydrogen; the other systems stores energy as heat in aluminum oxide. The first cystem (the solar energy-liquid hydrogen system) consists of ten components. The largest and most costly component is the solar collector. The collector considered ic of the concentrating type as heat is required at temperatures to 755 K. A heat storage nit. is requl-ed that is capable of storing all of the heat accumulated during the longest day ci the summer and storing this heat at temperatures to 755 K. A heat engine such as a Rankine or Stirling engine converts the heat in excess of that required for space heat- ing to rn'-chanical energy. The heat engine drives a dc generator which supplies power no electrol.vzer In electrolyze water. The hydrogen from the electrolyzer is then liquefied and stored to a dewar. Dewar boil-off gas is used in a hydrogen-air fuel cell to produce electricity for the households when the generator is not running. Heat rejected from the heat engine is used to heat water for domestic use. The system is depicted in figure 7.1. The operation of the system during the four seasons is generally as follows. During the summer, heat is collected during the day and some is used immediately to run the engine to generate electricity and produce liquid hydrogen. The remainder of the daytime heat is stored to be used during the night to run the engine and hydrogen producing equipment. Be- cause insolation is not constant, the short term heat storage is used so that the liquefier will run nearly continuously. Boil-off hydrogen gas during this time of year is reliquefied. Electricity for household use is taken from the generator and hot water from the rejected engine hat. l)uting rise spring and fall, when space heating is required intermittently, hydrogen so produced less ireqne.ntly and only when excess heat is available. Thus, the heat storage -it a used to stars the energy in excess of the household requirements and when the otoc;sge is near maximum, hydrogen is produced until the storage is at the lower temperature loft. Itien the generator Is not running, electricity is produced using boil-off gas in tse fuel cell. In winter, ii the sun shines, the solar collector produces nearly enough energy to net Ihe averss~e space heating requirement. When it is cloudy, hydrogen is burned to :upp~v ,~sst ~rd st water. The fuel cell supplies ele~trtc1ty using boil-off gas or gasified arr,ntement p'ovides I o -arcyino the great excess of summertime energy into hr. fete ,~ :hemieat feel ~lse oceensi system studied (the solar energy-heat storage system) stores heat energy its atunimum oxide at. two temperatures. The system consists of a concentrating solar collector, a low Lenspecutue e heat storage unit, a high temperature nest storage unit, a heat engine, an eletrice generator, and a hot water tearer --- see figure 7.2. Most of the solar energy PAGENO="1350" CA~ Hot Water Heater H20 Figure 7. 1 Solar-liquid hydrogen energy system. PAGENO="1351" Figure 7. 2 Solar energy system. Generator PAGENO="1352" 1346 collected in this system is stored at low temperature (360 to 755 K) for space and hot water heating. The rest of the energy is stored at high temperature (645 to 755 K) and is used to run the heat engine to drive the electrical generator. The solar collector and the heat storage units must be large enough to supply the required heat, hot water, and electricity needs for a specified period of cold, cloudy winter days. 7.3 SIZING SYSTEM COMPONENTS To size the system components, the energy requirements of the average household were needed. These were taken from a paper by P. A. Achenbach [1]. The data presented are from a subpanel report on total energy systems [2] and are for Baltimore, Maryland. These seasonal data were adjusted to a Boulder, Colorado environment by using the ratio of the sums of the respective geographic degree-days1 during the heating seasons. The monthly heating loads for Boulder were obtained by using the appropriate fraction of this total heating load as determined by the number of degree-days in each month. No change was made to the cooling loads. The cooling loads were assumed to be evenly distributed over the months of June, July, and August. Not water and electricity loads were assumed to be the same as those given for Baltimore. Design trade-off a can be made in sizing units such as the solar collector, heat storage, electrolyzer, and liquefier. Two extremes in solar collector sizes were analyzed in the study. The system using the smallest solar collector assumed that all energy collected over and above the daily requirements was converted to liquid hydrogen and is one of the systems described in section 7.2. For this system, the heat storage unit was small and was pri- marily used to run the engine; therefore, the assumed operating temperature levels of the heat storage were 645 to 755 K. The heat storage media was assumed to be aluminum oxide. The storage unit was sized so that the liquid hydrogen producing equipment would operate 24 hours a day during the summer. The heat engine, generator, electrolyzer and liquefier were sized to use this energy at maximum output. The fuel cell was sized to carry 200% of the average monthly load with air conditioning. The liquid hydrogen storage dewar was sized to accommodate the maximum amount of liquid that would accumulate if all of the excess energy were converted to liquid, i.e., enough hydrogen to last through 21 cold, sunless winter days. This dewar contains enough liquid, as of January 1, to last 12 cold (sunless) winter days. A cold winter day was assumed to use 150% of the average December day heat load. The solar collector was assumed to be as small as possible so that just enough energy is collected to run the system during an average year. The solar collector configuration used was a parabola of revolution with an assumed collection efficiency of 70% of the incident radiation. A concentration ratio of about 120 is required to attain the desired temperature of 755 K. The total monthly insolance and the average percentage of possible sunshine were taken from Strock [3]. The resulting available energy per square meter is given in table 7.1. 1 The degree-days for a given day are equal to the difference between the daily mean temperature (in degrees F) and a reference temperature of 65~F. The degree days in any period are the sum of the daily degree-days. PAGENO="1353" 1347 The second system uses the largest solar collector, no hydrogen storage and requires two temperature levels of heat storage, one for space heating and one for electrical generation. The heat storage media was also aluminum oxide. Since space heating can use temperature as low as 360 K or lower, this energy was assumed to be stored at temperatures ranging from 360 to 755 K. The energy storage for the generation of electricity was taken at temperatures of 645 to 755 K. The high temperatures were used to keep the heat engine efficiency at a reasonable level. The heat engine was therefore assumed to operate with input temperature from 645 K to 755 K and rejection temperatures at 340 K. The assumed thermal efficiency was 30% which is high for the lower temperature but reasonable for the maximum temperature. This system was then sized to provide energy storage for a maximum of 8 cold winter days. Table 7.1 Solar heat at Boulder, Colorado, per month Month W-h/m2 Jan. 98,667 Feb. 111,288 Mar. 166,629 Apr. 185,480 May 208,775 June 205,353 July 208,775 Aug. 185,480 Sept. 166,629 Oct. 111,288 Nov. 98,667 Dec. 92,018 7.4 ESTIMATED PERFORMANCE OF SYSTEM COMPONENTS Each component of the system was assigned efficiencies comparable with existing equip- ment or in the case where equipment is not available, efficiencies were assigned similar to the values predicted by those developing the equipment. The efficiencies used were 90% for heat exchange, 80% for combustion, 30% for engine and generator combined, 78% for electrolyzer, 51% for the fuel cell, 30% for the liquefier and 70% for the solar collector. Of all efficiencies estimated, the solar collector is the least credible as no data were available for this type of collector. 7.5 COMPARISON OF THE OPERATION OF SYSTEMS Since the hydrogen system is complex, system operation will require full-time monitor- ing. The collector temperature must be higher than the temperature of the storage unit before heat can be added. The heat in storage must be compared to the projected space heating re- quirements before the decision is made to run the liquefier since liquefaction includes 62-332 0 - 76 - 86 PAGENO="1354" 1348 several low level efficiencies that result in greater energy losses. In the suumer the liquefaction rate would need to be adjusted so that the operation is as near continuous as possible since warmup and cooldown of the liquefier represent energy losses. Several features of the hydrogen system do provide for advantages over the simpler system of dual temperature storage. The most significant advantage is that the liquid hydrogen system can be fueled from an exterior source in the event of a component failure or an extended local cold, cloudy period of weather. The fuel cell and the hydrogen-fired boiler could assure continuous supply of electricity and heat as long as liquid hydrogen was provided to the liquid storage dewar. This dewar has a capacity to handle 21 cold winter days or 30 days of average winter-day energy consumption. The second operational advantage is that the system normally has a minimum of 12 cold winter days energy on hand as of January 1, where the nonhydrogen system can store only an 8-day supply. This 8-day supply of energy requires that the heat storage be at a maximum. To get maximum heat storage, more than 16 totally sunny and consecutive days are required preceding the 8 cloudy days. This is an unlikely series of events. A third advantage of the liquid hydrogen system is that there is redundancy in the heat and electrical supply in the event of a solar collector failure or an engine-generator failure. The hydrogen-fueled boiler can provide space heating and the fuel cell provides electricity. In the event of a fuel cell failure, the generator could be run from the hydrogen-fueled boiler and the heat engine. Stand-by heat and power sources could be supplied for the non-hydrogen system at additional costs. 7.6 COSTS Capital, operation, and maintenance costs of each unit were determined from informa- tion taken from the literature. These costs are given in chapter 2. The cost of capital, insurance, and profit was assumed to be 15% and was amortized over 20 years. This amortiza- tion time may be extensive for some components such as fuel cells and solar collectors. Data on fuel cells are not available because coimnercial units have not been in existence many years. Also, no data exists on solar collectors of the highly concentrating type re- quired. Because of this lack of substantiated data, the 20-year period was assumed as the most reasonable for all equipment. The unit cost that could not be estimated with any degree of confidence was that of the solar collector. Since the solar collector is the major cost item and actual costs were not known, a study of the effect of solar collector cost on final energy cost was made for $20 to $110 per square meter of collector. The capital costs of the other items used for the analysis are given in table 7.2. The re- sulting cost per kilowatt hour of energy versus cost per square meter of solar collector is shown in figure 7.3 for three systems. The liquid hydrogen system and the system desig- nated as an S-day dual temperature system are the two systems described earlier. The ~-dav single temperature system is a conventional non-hydrogen solar system considered ccrparison. In this system all heat is stored at 645 to 755 K and a maximum of 4 sunless, cold winter days of energy is stored. Also, for comparison purposes, the current operating costs for similar households using electricity with natural gas, heating oil and propane are shown and the separate cost of the electricity is shown. As is evident from the figure, the total energy costs are very sensitive to the cost of the solar collector, PAGENO="1355" * 080 .070 E .060 C) .050 C) ~-` .040 (0 cc LU .030 _-BOULDER/ELECTRICITY COST f .020 ~-B0ULDER WITH PROPANE @ 38Ugal & ELECTRICITY @2.52i~/kW-h 010 -BOULDER WITH OIL B 3O~/gal & ELECTRICITY B 2.52UkW-h -BOULDER WITH NATURAL GAS B 8.5~/lOO ft3 & ELECTRICITY B 2.52~/kW-h C 0 120 1349 *Calculated using 150% and avg hot water & el *4 day single temperature storage load on temperature 20 40 60 80 100 COST OF SOLAR COLLECTOR, DOLLARS/rn2 Figure 7. 3 Cost of energy versus solar collector costs. PAGENO="1356" 1350 and the energy costs for the solar systems considered are all higher than current energy costs where solar collector costs exceed $20 per square meter. The hydrogen system is competitive with the other solar systems in the range of 40 to 70 dollars per square meter solar collector costs and also provides the previously mentioned advantages. Table 7.2 Size and cost of solar energy system per residence (based on system components sized to service 100 residences) Unit Size Cost Heat storage tank 3.85 m3 $ 769. Al203 15,495 kg $ 900. LH2 Dewar 4500 liters $ 1340. Engine and generator 15.46 kW $ 471. Electrolyzer 24.3 kg/h $ 1035. Liquefier 2.27 kg/h $ 3000. Fuel cell 2.45 kU $678. Cost (less solar collector) $ 8193. Although many solar collector costs are proposed as low as $15 per square meter, only the very simplest flat pla~.e collector costs can approach this value, and these collectors provide energy at maximum temperature well below that required to run efficient heat engines. These collectors also collect less energy per unit area; therefore, they must be larger to collect the same amount of total energy. Since power generation is less efficient using lower temperatures, the low temperature system requires more energy than a high temperature system and, therefore, a larger solar collector. Thus, large area, low temperature collectors are required and land costs become important. It was not determined if the low temperature system produces electricity at lower costs than a high temperature s;stem because low temperature heat engines are not currently available. Consequently, the conventional high temperature heat engine was selected for analysis. Electrical energy can also be supplied using photovoltaic cells, but the current state- of-the-art results in very expensive units of low efficiency. Again, there is a trade-off if the photovoltaic cell can be produced cheaply. The trade-off occurs between large areas of low efficiency cells versus less area of a higher efficiency solar collector system. lie current cells convert solar energy to electricity at efficiencies of 5 to 7% while the efficiency of the electrical system proposed is about 20%. The proposed system includes storuce capability for cloudy dais and for might time. To provide full-time power in a ~rrovulL~i2c soster., batteries or some other electricity storage media would be needed. U'st corrp;rrisons of these systems were not justified at this time since their are no real cost data for photovoltaic cells for cormrrrercial use. PAGENO="1357" 1351 7.7 REFERENCES [1] Achenbach, P. R., Effective Energy Utilization in Buildings, Paper presented at 3rd Urban Tech. Conference, Boston, Massachusetts, (September 25-28, 1973). [2] Subpanel Reports on Total Energy Systems, Urban Energy Systems, Residential Energy Consumption, submitted by the Department of Housing and Urban Development, Federal Council on Science and Technology (July 1972). [3] Strock, C., Handbook of Air Conditioning, Heating and Ventilating (Industrial Press, New York, N.Y., 1959). PAGENO="1358" 1352 CHAPTER 8 INDUSTRIAL APPLICATIONS OF HYDROGEN W. R. Parrish 8.0 SUMMARY Large quantities of hydrogen are consumed in a variety of industries. Most of the hydrogen is used in ammonia and methanol syntheses, hydrocracking, and hydrotreating. Smaller quantities of hydrogen are needed in manufacturing drugs, processing metals, and hydrogenating fats and oils. Hydrogen consumption is expected to double by 1985; however, large scale coal liquefac- tion and shale oil processing will greatly increase the demand. 8.1 INTRODUCTION In 1972, U.S. industries consumed roughly 6.5 x lO~ kg of hydrogen 11]. More than 98 percent of this gas had a purity of less than 99.5 percent. The majority of the low purity hydrogen went into petroleum refining and the production of ammonia and other chemicals. High purity hydrogen C> 99.5 percent) was used in manufacturing drugs, processing metals, and hydrogenating fats and oils. Table 8.1 gives a rough breakdown of hydrogen usage during 1972. Based on a 20-year trend, hydrogen consumption will nearly double by 1985; however, two future technologies, coal liquefaction and shale oil production, could greatly increase the demand. Table 8.1 Estimated usage of hydrogen in l972~ Process Ammonia Synthesis 35 Hydrocracking 30 Hydrotreating 21 Methanol Synthesis 8 Other 6 1. These estimates are from Harper [1]. 8.2 PETROLEUM REFINING There are two processes in refineries which use large quantities of hydrogen: hydro- treating and hydrocracking. Hydrotreating uses hydrogen to reduce sulfur compounds in petroleum fractions to H2S, which is easily removed, and to upgrade lubricating oils and kerosene. The process con- sumes roughly 500 cubic meters of low purity hydrogen for each cubic meter of hydrocarbon liquid processed. The primary source of hydrogen for hydrotreating is catalytic reforming, a process which increases the octane rating of gasoline components. Hydrocracking is a catalytic process of increasing the hydrogen-to-carbon ratio of high-boiling petroleum fractions such as low quality heating oil and tars. Thus, it com- PAGENO="1359" 1353 verts low value materials into the more valuable lighter hydrocarbons by breaking down long-chained molecules. The process requires 4600 to 5000 cubic meters of hydrogen for each cubic meter of feedstock converted. Based on current trends and anticipated expan- sion plans, hydrocracking will constitute the largest single use of hydrogen in this country. 8.3 AMMONIA PRODUCTION Each year, ammonia production consumes more hydrogen than any other process. It takes around 20 cubic meters of low purity hydrogen to produce 1 kg of ammonia. Over 75 percent of the ammonia is converted into fertilizer, and most of the remainder is used to manu- facture explosives. Currently, natural gas is the major source of hydrogen for ammonia production. 8.4 OTHER USES OF HYDROGEN In addition to the above processes, hydrogen is used to produce various other chemicals, the major one being methanol. Methanol is used as a solvent and as an Intermediate for the production of many other chemicals. To a lesser extent hydrogen is used to produce oxoalco- hols, cyclohexane, hexane, and many others. Hydrogen plays a major role in the hardening of vegetable and fish oils e.g., the production of margarine. Hydrogenating fatty acid oils, primarily cottonseed and soybean oils, produces lard, oleo margarine, and shortening. Nonedible hardened oils are used in the soap industry and to a lesser extent in leather dressings, electrical insulations and pharmaceutical ointments. Hydrogen is important In metallurgical ore reduction and annealing, in glass manu- facturing, and in drug synthesis. However, these applications consume small quantities of hydrogen when compared to petroleum refining and the production of ammonia and methanol. 8.5 FUTURE USES OF HYDROGEN It is impossible to foresee all of the future applications of hydrogen in industry; however, shale oil upgrading and coal liquefaction represent major potential consumers of hydrogen. Whereas petroleum stocks usually contain sulfur compounds, shale oil can contain up to two percent nitrogen as well as one percent sulfur [2]. Therefore, shale oil has to be hydrotreated to remove the nitrogen and sulfur before it can be used as a fuel oil or processed to make more valuable liquids. The hydrotreating requires roughly 3700 cubic meters of hydrogen per cubic meter of shale oil [2]. In terms of hydrogen consumed per unit of stock processed, coal liquefaction will constitute the largest use. To produce one cubic meter of synthetic liquid requires roughly 13,000 cubic meters of hydrogen, nearly 25 times more than required in hydrotreating. So, when coal becomes a major source of hydrocarbon liquids, vast quantities of hydrogen will be needed. PAGENO="1360" 1354 8.6 REFERENCES [1] Pennington, J. W., and Harper, W. B., Bureau of Mines, Washington, D.C., personal cotitmunication to the author (1974): See also Meadows, D. P., and De Carlo, J. A., Mineral Facts and Problems, Edited by W. A. Vogely, p. 97, U.S. Bureau of Mines Bulletin 650, Washington, D.C. (1970). [2] Hellwig, K. C., Fergelman, S., and Alpert, S. B., Upgrading feeds by the H-Oil Process, CEP 62, No. 8, 71 (Aug. 1966). PAGENO="1361" 1355 CHAPTER 9 HYDROGEN FUEL LITERATURE Neil A. Olien 9.0 SUMMARY The Cryogenic Data Center has as its mission the identification, acquisition, storage, retrieval and critical evaluation of information and data on the properties of materials at cryogenic temperatures. In addition, an information service is provided for the entire field of cryogenics. In 1973 a survey was made of the world's technical publications in order to add to our present coverage so that we can adequately review those publications containing informs tion on hydrogen. Prior to this the coverage was adequate for cryogenic hydrogen, but it was necessary to add to the review in the energy field to locate hydrogen-fuel information. In addition, a retrospective search has been made to locate papers in the literature prior to 1973. This search is nearly complete and the results have been incorporated into a preliminary bibliography on hydrogen-fuel. A more complete version of this will be avail- able in December 1974. The Cryogenic Data Center has now published and distributed four copies of a quarterly literature survey entitled Hydrogen-Future Fuel. This is completed each August, November, February and May. Each issue lists some 300-500 references under 40 subject headings. An author index is included with each issue. The Cryogenic Data Center has been working with the Aerospace Safety Research and Data Institute (ASRDI) of NASA since 1970 in an effort to compile all available information on cryogenic fluid safety. The initial effort was on oxygen, but was expanded to include hydrogen in 1972. This effort has resulted in the location and careful indexing and ab- stracting of over 500 safety-related papers on hydrogen safety. This information is now available for searching using an on-line search system operated by ASRDI. A major data compilation is now underway which will produce a Hydrogen Properties Handbook. This effort is also sponsored by ASRDI and will provide a single source, internally consistent set of data for the thermophysical properties of hydrogen. 9.1 INTRODUCTION All surveys, reviews and state-of-the-art assessments begin with, and must ultimately rely on the literature covering the field. The purpose of this chapter is to summarize the efforts made to provide an adequate coverage of the published, report and patent litera- ture dealing with the possible widespread use of hydrogen as a fuel. There has, therefore, been a large amount of cooperation between various groups within the Cryogenics Division as regards the information covering the field of hydrogen fuel. 9.2 THE CRYOGENIC DATA CENTER The Cryogenic Data Center was established [1] in 1958 to assist the staff of the Cryogenics Division and other organizations within the National Bureau of Standards, other Government Agencies, industry, and universities in keeping up with the flood of information in this multi-disciplinary field. The field of cryogenics is, after all, defined by a temperature range rather than by subject or discipline. PAGENO="1362" 1356 From its inception the Center has been divided into two operational groups -- a Documentation Group to provide information services in the field of Cryogenics and a Data Evaluation Group to compile and critically evaluate thermophysical properties data of the technically important gases. The latter group has produced Standard Reference Data for the properties of helium [2], nitrogen [3], hydrogen [4] and argon [5], is completing work on hydrogen and is beginning work on fluid mixtures. In addition a long term project, supported by the NBS - Office of Standard Reference Data, has produced tables of transport properties data for monatomic and polyatomic fluids [6,7] in the dilute and dense phase regions. This effort also will soon become directed toward mixtures. The Documentation Group maintains a thorough and systematic review of the current published, report and patent literature by means of a regular review of over 350 primary publications, supplemented by a cover-to--cover scan of some 30 abstracting services. The first step in the operation of this information system is the preparation of a weekly Current Awareness Service for the Cryogenics Industry. All important references listed in this service are entered into an automated information storage and retrieval system. The most important step in this entry process is careful subject indexing by professional scientists and engineers. Once the information is in the information system it is avail- able for retrieval by means of a number of access points and thus provides the basis for a number of information products. During the winter and spring of 1973 the staff of the Data Center made a thorough survey of the world's technical literature to determine how best to cover the hydrogen fuel field. The result, which was instituted in July 1973, was a net change of nearly 100 pri- mary publications and 10 abstracting services reviewed. The new material being added to the information system to cover hydrogen amounted to an increase of over 20 percent (7500 - 8000 documents are entered in a normal year). This increase was not possible, of course, with a fixed budget and staff. The new additions were offset by reducing the coverage in certain areas of solid state physics, notably the semiconductor field. This redirection of effort during the past year has been a great success and quite healthy for the Cryogenic Data Center. This new expanded coverage for hydrogen fuel has also been incorporated into the Current Awareness Service and appears there under Section III - Energy. 9.3 SERVICES AND PRODUCTS OF THE CRYOGENIC DATA CENTER The Cryogenic Data Center provides a number of services and products, most of which are available on a cost reimbursable basis. a) Current Awareness Service -- a weekly bulletin averaging 8 - 10 pages listing new publications in the fields of low temperature physics and chemistry, cryogenic engineering and energy. Each issue contains a subject index. It has been published each week since 1964. Subscriptions are available from the National Technical Information Service, Springfield, Virginia 22151. Price: $20/year-domestic; $25/year-foreign (includes airmail delivery). PAGENO="1363" 1357 b) Superconducting Devices and Materials Qua~ rly~ -- published each January, April, July and October since 1968. This is a joint publication including participation from staff of the Office of Naval Research, the Naval Research Laboratory and Superconducting Technology, Inc. Each issue includes approximately 300 - 500 references divided into 41 subject areas and includes an author index. In addition a summary of the important papers in each issue is included. This is written by Dr. Robert A. Kamper of the NBS-Cryoelectronics Section and has proved to be a useful and popular column. Subscriptions are available from the National Technical Information Service, Springfield, Virginia 22151. Price: $20/year. c) Liquefied Natural Gas -- published each January, April, July and October since 1970. This publication is sponsored by the American Gas Association and covers this new and rapidly expanding industry which is closely related to the hydrogen-fuel industry. Each issue includes 100-300 references listed under 25 subject headings -- an author index is included as well. Subscrip- tions are available from the National Technical Information Service, Springfield, Virginia 22151.) Price: $20/year. d) Hydrogen - Future Fuel is a new periodical which has been distributed in August, November, February and May since August 1973. This publication is a direct result of the efforts described in section 9.2. It is obvious that a comprehensive publication could not be produced in August 1973 when the effort was started in July. The first issue tapped the information contained in the Cryogenic Data Center's information system and was, in essence, a selected bibliography of liquid hydrogen technology. Since then, issues have listed mainly new references in the field. Each issue contains 300 - 500 references listed under 40 subject headings and includes an author index. Subscriptions are available without cost by writing to: Mr. Neil A. Olien, Cryogenic Data Center, National Bureau of Standards, Boulder, Colorado 80302. e) ~p~ējalized Bibliog~p as -- The information bank maintained by the Cryogenic Data Center now contains over 80,000 carefully indexed references in the field of cryogenics. These include 20,000 references to the properties of fluids, 35,000 references to the properties of solids, 15,000 references on processes and equipment (including a very complete selection of U.S. Patents) and 10,000 references to instrumentation and metrology. This information bank can be tapped to provide specialized bibliographies on any subject. The searches are made by the same professional staff that index the documents. This results in bibliographies containing maximum information with minimum volume. Searches start with a minimum of $35 and average about $45. For further information contact Neil A. Olien, Cryogenic Data Center, National Bureau of Standards, Boulder, Colorado 80302, or telephone (303) 499-1000, ext 3257. PAGENO="1364" 1358 f) Fluid Properties Computer Programs -- The Data Evaluation Group has developed a number of general purpose computer programs for fluid properties which are made available on a cost reimbursable basis. For further informa- tion see Table 9.1. g) ~pg4~Lized Zibliogr$p~4~ -- In order to expand the usefulness of the Data Center's information bank we have begun a series of widely useful bibliographies. Two of interest here are: q~gfied Natural Gas Technology, October 5, 1973, Order No. COM-74-l0324 - $7.00, Foreign $9.50. Energy and Superconductivity, March 20, 1974, Order No. COM-74- 10713 - $7.00, Foreign $9.50. Send Orders to: National Technical Information Service 5285 Port Royal Road Springfield, VA 22151. In addition to these we have prepared a summary bibliography on hydrogen- fuel. This is still a preliminary publication because it does not yet contain all of the results of the efforts described in chapters 1 through 8. A more complete bibliography will he available in December of 1974. Requests should be directed to: Neil A. Olien, Cryogenic Data Center, National Bureau of Standards, Boulder, Colorado 80302. 9.4 HYDROGEN SAFETY INFORMATION The Cryogenic Data Center has cooperated with the Aerospace Safety Research and Data Institute (ASRDI) of the National Aeronautics and Space Administration (located at Lewis Research Center, Cleveland, Ohio) since 1970 in an effort to locate, catalog, carefully index and evaluate the literature relevant to cryogenic fluid safety. Initially this effort was directed toward oxygen safety, but has since been expanded to include hydrogen and beginning October 1, 1974 methane and LNG. ASRDI has developed a sophisticated infor- mation system of which the information we have supplied on cryogenic fluid safety, com- prises a major part. In the near future, the ASRDI information bank will be available, through a nationwide computer network, on a real-time basis. 9.5 HYDROGEN PROPERTIES HANDBOOK The Data Evaluation Group, with funding from NASA-ASRDI, is currently completing a major compilation of the thermophysical properties of hydrogen. This will be similar to a handbook [8] of oxygen properties prepared two years ago. The hydrogen effort will bring together under one cover, data which are scattered throughout the literature. Even more important the data will be made internally consistent and will be extended into regions for which data presently do not exist. The manuscript and associated tables will be completed by October 1974. The medium of publication is a NASA Special Publication which should be available in early 1975. The computer programs used to generate the tables will be made available by NBS at cost. PAGENO="1365" Table 9.1 PROPERTY DATA AVAILABLE FROM THE NATIONAL BUREAU OF STANDARDS Fluid Document Program Name Program Range Input Output Type Acy P T Ar NBS-NSRDS 27 AR PROPS BWR, 16 1 1000 atm TP-3SS K P-T, p-T P,p,T,S,H,U CO NBS TN 252 CO PROPS BWR, 16 1 400 atm 70-300 K P-T, p-T Pp T,S,H,U O~ D~ BWR, 24 1 455 attn TP-350K P-T, p-T P,pT,S,H,U F, NBS TN 392 No reference SAMPLE, PVT F, Never issued Poly Int 1 BWR, 24 2 24 MN/m° 240 atm TP-305 K TP-355 K P-T P-T, p-T PpTSHUCpCv. (~)p~ (~~)~w P,p,T,S,H,U He NBS TN 631 Do NBS TN 184 HE PROPS (71) HE PROPS (70) HE PROPS (62) BWR, 87 1 BWR, 35 2 BWR, 17 3 1000 atm 1000 atm 150 atm LP-1SSS K LP-ISSO K 3-300 K P-T, p-T P-T, p-T P-T, p-T P.p.T.S~H~U.Cp.Cv. 9, 9 and others PpTSHUCpCv. t~~'t, (~)j,w P,p,T,S,H,U H0 (Para)(Equi Para NBS Mono 94 NBS TN 130 In Preparation NBS TN 625 NBS TN 617 THERMO or PROP TRSasd PROP LIQ H2HIP TAB CODE H2 PROPS Poly tnt 1 BWR, 16 2 BWR, 16 2 BWR 2 Lie 1st 3 BWR, 17 1 THERM 1 340 atm 340 atm 340 atm 700 atm 5000 psi 10,000 psi bOSS psi TP-155 K 33-300 K TP-32 K TP-755K TP-650S B 180-6000 R TP-l8S N P-T P-T, p-T P-T, p-T P-T, p-T P-T, P-H P-T, p-T P-T PpTSHUCpCv ~ P,p,T,S,H,U P,p,T,S,H,U,C,C, W,T9K P,p,T,S,H,U,C,C,K,11,W (all of above plus, 8, 5,8,Pr,0,~ and others) P,p,T,S,H~U,Cp,Cv, CH5 NBS Report METHERM 4 Non-Ana 1 10,000 p5i TP-550 K P-T Ne ASME Advances 65 R- 346 NE PROPS BWR, 18 1 255 atm 253SS K P-T, p-T P,p,T,S,H,U N2 ~4nB~r~Ia;ation N0 PROPS BWR, 32 1 1S,OSOatm 64-1900K P-T, p-T Same as H2, 0~ and He O~ Stemart, J. Res, 70, R-559 NBS TN 384 0, PROPS PVT 02 PVT 02 & TEST BWB, 32 2 Poly 1st 1 poly lnt 1 340 atm 340 atm 5000 psi 65-300 K TP-300 K TP-650 N P-T, p-T P-T P-T PpTSHUC~,C ,(~-~) (~!~ `w pT P 9p T (all of above 8, 8, 8,B,Pr,o,y,K,11 and others) Acy - A relative indication of accuracy. 1 Bent accuracy, 3 = Poorest accuracy PAGENO="1366" 1360 We feel that this Handbook will serve as the "Standard" data for hydrogen. This will sake it particularly useful as it will serve as the same data base for everyone when cycles and processes involving hydrogen are compared. It is obvious that meaningful com- parisons cannot be made between competing systems unless a cot~ion data base is used. This summarizes the efforts, products and services of the NBS-Cryogenic Data Center for providing information services to the cryogenics industry and particularly that part associated with the energy field. The emphasis of the Data Center's efforts is on the low temperature portion of the hydrogen fuel field, although we do cover higher temperature areas when those areas are related to cryogenic hydrogen. PAGENO="1367" 1361 9.6 REFERENCES 1] Olien, N. A., The Cryogenic Data Center, An Information Service in the Field of Cryogenics, Cryogenics 11, 11-18 (Feb. 1971). [2] McCarty, R. D., Thermophysical Properties of Helium-4 from 2 to 1500 K with Pressures to 1000 Atmospheres, Nat. Bur. Stand. (U.S.), Tech. Note No. 631, 161 pages (Nov. 1972). [3] Jacobsen, R. T., Stewart, R. B., McCarty, R. D., and Manley, H. J. M., Thermo- physical Properties of Nitrogen from the Fusion Line to 3500 R (1944 K) for Pressures to 150,000 PSIA (10342 x 10~ N/m2), Nat. Bur. Stand. (U.S.), Tech. Note No. 648, 162 pages (Dec. 1973). [4] McCarty, R. D., and Weber, L. A., Thermophysical Properties of Parahydrogen from the Freezing Liquid Line to 5000 K for Pressures to 10,000 PSIA, Nat. But. Stand. (U.S.), Tech. Note No. 617, 169 pages (Apr. 1972). [5] Gosman, A. L., McCarty, R. D., and Hust, J. G., Thermodynamic Properties of Argon from the Triple Point to 300 K at Pressures to 1000 Atmospheres, Nat. Stand. Ref. Data Series-Nat. But. Stand. No. NSRDS-NBS 27, 150 pages (Mar. 1969). [6] Manley, H. J. M., and Prydz, R., The Viscosity and Thermal Conductivity Coeffi- cients of Gaseous and Liquid Fluorine, J. Phys. Chem. Ref. Data 1, No. 4, 1101-1114 (Oct.-Dec. 1972). [7] Hanley, H. J. M., The Viscosity and Thermal Conductivity Coefficients of Dilute Argon, Krypton, and Xenon, J. Phys. Chem. Ref. Data 2, No. 3, 619-642 (1973). [8] Roder, H. M., and Weber, L. A., ASRDI Oxygen Technology Survey Volume I: Thermophysical Properties, NASA Spec. Publ. No. NASA SP-307l, 430 pages (1972). PAGENO="1368" HBS.114A tOPS. 1362 U.S. DEPT OF COMM. 1. I'UIILICATION OR R1(I°ORT NO. 2. GOD' Ass. ~io BIBLIOGRAPHIC DATA N0. SHEET NBSIR 75-803 3. 5~. pitt's A5ssjo N~. 4 *FFFLF AN!) SUIIIlIlL SELECTED TOPICS ON HYDROGEN FUEL 5. PshIj,tj~ I)tt~, January 1975 6. PFtIOtOtD~ 0t5~0~0C5 (oh 7. AUFIIOR(S) J. Hord (Editor), W. R. Parrish, R. 0. Voth, B. PttIstsiog Otgoo. Spot N... 2. G. Host, T. N. Flynn, C. F. Sindt, N. A. Olien 9. PERFORM)N(; ORGANIZATION NAME AND ADDRESS NATIONAL BUREAU OF STANDARDS DEPARTMENT OF COMMERCE WASHINGTON, D.C. 20234 10. Poj~o'ToskW~ ((it N. 2750154 Il,C~o~stG~otNto 2. SP005UOtCG Otg. ttss Noto to) (ootplots Addtpss (Sttppt City. Stotp, ZIP) 13. Ivps of Rsp~tt & Pstiod Final l4.Spoo~iogA-oss(,.. IS. 0!'II'IIMENTAEY NOtES 16. Al)',! RA( I (A 200-ootd st loss f~oS~tl ODttt!OOOy of stool si~tifioattt ittfotot~tion. If doooototte io~lodps sigoifiso,t( biltliogtopht st )itFt.ttotoootFoy, meoliott iI ltppp.) The National Bureau of Standards played a vital role in developing hydrogen technology for the space age and is now engaged in efforts to adapt and improve this technology for the commercial use of hydrogen fuel. This document is a summary report on selected hydrogen-fuel topics and was prepared to identify cost and technical barrier to the con'.rnercial use of hydrogen fuel and to generate reference data for policy- planning, decision-making and design. Cryogenic hydrogen fuel technology is emphasized in the economic and systems analyses reported herein. Using the best available technical and economic data, hydrogen fuel is not currently cost competitive with alternate fuels; however, we must not reject hydrogen on the basis of current economic comparisons. Increased efficiencies of production, liquefaction, and energy conversion may drastically change these comparisons-of-today as will increased fossil fuel prices and more stringent environmental and pollution constraints. Hydrogen appears currently marketable in certain integrated utility systems, in transoceanic transport of energy produced far at sea, and is a necessary element in a wide variety of growing industrial processes and in the liquefaction of coal. This publication identifies research and development needs within selected areas of NBS competence and future research plans are outlined. 17. kit 0 (5))- (sis to tottop ~otttps; otph~bttit~) otdop; Fopitotiop ottty tht' fits! tottos of tho fisot ks's sotd sotsos U s..sspttsIby.sposotso) Conservation; conversion; cost; cryogenics, economics; embrittlement; energy; hydrogen; industrial, instrumentation, liquefaction; literature; materials; production; solar; storage; transmission; transportation; utilities. 18. SV\I) AsII.IT't (Jolitsitpd 19. SECURITY CLASS 21. No. OF PAGES THIS REPOIIT) st Goc,. I I)isttilstioo. 1)0 Not Ct) POOP to NTIS UNCLASSIFIEI) SUp. of lop., U.S. Gooptotopot Ptiotiog Oflipt 20. SECURITY CLASS 22. Ptiop Rtskis5tos, [IC. 20(02, SI) CUt. No. C13 (THIS PAGE) -. Otis, I too No, sot) TPChtOPUI Iofottoottoo So~ipe (NTIS) Syoo~Iit)), Vttgsttt 221st UN(:LASSIIIEI) 0