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Solar-Hydrogen Energy Systems
Int. J. Hydrogen Energy, Vol. 8, No. 1, pp. 63-64, 1983. Pergamon Press Ltd. Printed in Great Britain. International Association for Hydrogen Energy.
BOOK REVIEWS Solar-HydrogenEnergySystems:edited by Tokio Ohta.
In the context of the book's title, one would presume that the direct current electrical input for electrolysis would be derived from solar radiation by either photovoltaic or thermal electric conversion processes. For the sake of completeness, It would have been salutary to include state-of-the-art reviews of these techniques, at least as appendices. This would have provided a useful 'benchmark' for comparing the cost and practical efficiency of transforming solar radiant energy into hydrogen energy via the electric----electrolytic route with those claimed or anticipated from the photoelectrochemical and the photo-thermo-electrochemical hybrid processes described in Chapters 6 and 7. The decomposition of water by heat, i.e. through direct thermolysis and multistep thermochemical closed cycles, is reviewed in Chapters 4 and 5 with appropriate and adequate thermodynamic treatments. High temperature thermolysis of water can be of little more than academic value for hydrogen production in view of the virtual impossibility of finding a practical means of separating the H and O species as rapidly as they are formed. The description of thermochemical cycles (Chapter 5) is a bit too general on the experimental side. Reviews of computational procedures for process optimization (exemplified with sample computer programs) and of typical demonstrative experiments resulting in the net continuous conversion of H20 to H2 + ½02 (e.g. those of the Ispra-Euratom group) could have been included to illustrate recent advances. Turning to the important aspect of heat source, it is surprising that whilst the nuclear H T G R is emphasized as uniquely suited, there is hardly any reference to the adaptability of solar heat for TC water-splitting despite the impressive advances in this direction reported by the General Atomic Company of the United States. In logical sequence, the next three chapters relate to water-splitting processes employing light quanta, namely photochemical and photoelectrochemical conversions in inorganic and biological systems. Besides projecting the authors' own research, these chapters serve as good reference sources. In Chapter 8, Professor Akira Mitsui has outlined an excellent scheme for the utilization of marine algal and bacterial micro-organisms in the production of hydrogen and other valuable byproducts. In the introductory section of Chapter 6, the statement 'In a thermochemical water-decomposition cycle, the maximum attainable efficiency of energy conversion is limited by the thermal engine system that includes some endothermic reactions and at least one exothermic reaction' is misleading and opposed to the generally accepted theory of thermochemical cycles. It is well known that the Carnot engine limitation can apply only to the work involved in electrolytic steps, if any, product separation and inter-step transport of materials, and not to the chemical reactions per se.
Pergamon Press, Oxford, First edition 1979. xiii + 264 pp. Hardcover: (U.S.) $35.00.
Themes linking the most abundant energy-resource of the sun with the earth's most abundant material resource, namely water, to produce hydrogen have generated enormous interest among energy specialists because of the well-known and proven ideal fuel qualities of hydrogen, besides the environmental virtue of deploying solar energy to produce it from water. In recent years, there have been two notable documentations of the thoughts and technical implications of this concept. The first is the famous book of Professor J. O'M. Bockris, Energy: The Solar-Hydrogen Alternative, first published in 1975 and wherein a convincing case was made, firstly, for solar energy as the ultimate energy endowment for the survival of human civilization and, secondly, for hydrogen as the ideal 'carrier' of this energy. The second documentation is the recent publication under review. This work, which has been compiled by a very dedicated author and researcher in the field, Professor Tokio Ohta, focuses specifically on the experimental techniques for the dissociation of water by direct and indirect application of the sun's radiant energy. It is a logical and timely sequel to Professor Bockris's awakener book. A noteworthy feature of the new b o o k - - a feature which vindicates its claim as an 'authoritative review' of solar actuated watersplitting systems--is that each of its ten chapters has been written by specialists who have made significant contributions of their own to its title-topic. The first chapter, by Professor Ohta, is a synoptic outline of the book's scope. It contains a brief summary of the general characteristics of solar radiation and of the experimental methods of water decomposition elaborated in Chapters 3-8. Chapter 2 (also by Professor Ohta) provides the logical thermodynamic background to these processes. The third chapter (by Professor T. Takahashi) presents a balanced review of the theory and technology of water electrolysis, including the factors governing the efficiency of energy conversion and all the advanced types of water electrolysers that have been developed so far. However, the descriptions of the latter could have been enlightened with photographs of representative commercial versions. The schematic line drawings are poor substitutes as they fail to convey a proper impression of the plant's appearance. Further, considering the enormous amount of development research on water electrolysis technology carried out in Japan (the birthplace of this book), it is very surprising that there is hardly any reference to Japanese work in this chapter. 63
64
BOOK REVIEW
Chapter 9 differs from the preceding chapters in the sense that it relates, not to the production of hydrogen, but rather to the interaction of hydrogen with metals to form decomposable metal hydrides and the utility of the thermochemistry of this interaction for the storage of thermal energy and for some innovative thermomechanical applications employing hydrogen as the working fluid. The inclusion of this chapter is quite appropriate because of its practical implications for solar energy storage and heat-pump applications. Predominance of coverage is given to the current on-going research of the author on these topics to the virtual exclusion of more significant and more extensive work carried out in the U.S.A. and Europe, except for the one prime reference to the work of Gruen et al. of the Argonne National Laboratory. The last chapter (Chapter 10) is totally different from the preceding ones in that it does not concern in any manner the techniques of production and utilization of hydrogen as an energy vector, but stresses a labored plea for choosing marine locales for all kinds of solar energy games, including hydrogen production. Clusters of huge rotating floats are proposed for this purpose. On the authors' own showing (Table 10.1), the specific areal conversion of solar radiation works out to barely
Hydrogen Power: An Introduction to Hydrogen Energy and its Applications: by LAURENCE O. WILLIAMS.Pergamon Press Ltd., Oxford, 1980. ix + 158 pp. $29.00. The title of this book is quite fitting. Larry Williams, its author, has packed into 150 plus pages all that the layman would desire to know about hydrogen. The style is straightforward and interesting. Tables, charts, graphs and photos supplement the text nicely. Trivia buffs may find it lacking. There are few anecdotes. The author makes his statement in lean, concise terms. Only in the chapter on the physical and chemical properties of hydrogen does he slip off the deep end. Even then, however, his thorough knowledge of the subject and his ability to convey difficult concepts will help pull the reader through the more esoteric passages. The more complex material is necessary to show how much hydrogen is already a part of our daily lives. At the time the book was written, Mr. Williams was the Manager of Hydrogen Programs at the Aerospace Corporation in Germantown, Maryland, U.S.A. Although the book is comprehensive--he covers the history, properties, uses, production, transportation and storage, safety and energy carrier potential--it is not entirely objective. Sometimes the author's enthusiasm for hydrogen's prospects are not always muted.
10 W per m 2, which is roughly one-third to one-quarter of that achievable with land-based solar thermal-electric or photovoltaic conversion. Surprisingly, the technique of OTEC receives only brief mention, because according to the authors, OTEC is indirect solar energy conversion. The five appendices at the end of the book contain useful data regarding solar radiation, hydrogen, energy units and conversion factors, and general physical constants. Only a subject index is provided. The customary addition of an Author Index would have been very useful for quick spotting references. On the whole, this book is a highly useful source of information to those working in any area of solar energy conversion. To one who firmly believes that conversion to hydrogen is perhaps the most practical solution for massive (multi-megawatt scale) utilization of solar radiant energy on earth and the ultimate and lasting solution to the energy resource problem, this work is timely and welcome.
Energy Cell, University of Madras, Madras 600005, India
M. V. C. SASTRI
But I find this refreshing! It gives life to what some may consider just another textbook. The writer has conveniently placed pertinent bibliographic references at the end of each chapter, rather than at the end of the book, which is useful. He has also included a list of organizations involved in current research so that the reader, if he or she so desires, could follow up directly. Hydrogen Power gives an excellent overview of the many faceted element. The author provides, when necessary, the depth to make understanding of some applications and/or properties easier. The book has only seven chapters and their titles do not always convey their complete contents. Mr. Williams has covered every aspect of the subject and the inclusion of some material in a particular chapter is not in the least bit strained. For example, in the chapter, Hydrogen As an Energy Carrier, information about hydrogen's use in automobiles and aircraft is included. Technically these would be end uses rather than carrier applications but because of the book's brevity, a simple format is essential.
P.O. Box 362, South Lake Tahoe, CA 95705, U.S.A.
H. R. HINDS
BOOK REVIEWS Solar-HydrogenEnergySystems:edited by Tokio Ohta.
In the context of the book's title, one would presume that the direct current electrical input for electrolysis would be derived from solar radiation by either photovoltaic or thermal electric conversion processes. For the sake of completeness, It would have been salutary to include state-of-the-art reviews of these techniques, at least as appendices. This would have provided a useful 'benchmark' for comparing the cost and practical efficiency of transforming solar radiant energy into hydrogen energy via the electric----electrolytic route with those claimed or anticipated from the photoelectrochemical and the photo-thermo-electrochemical hybrid processes described in Chapters 6 and 7. The decomposition of water by heat, i.e. through direct thermolysis and multistep thermochemical closed cycles, is reviewed in Chapters 4 and 5 with appropriate and adequate thermodynamic treatments. High temperature thermolysis of water can be of little more than academic value for hydrogen production in view of the virtual impossibility of finding a practical means of separating the H and O species as rapidly as they are formed. The description of thermochemical cycles (Chapter 5) is a bit too general on the experimental side. Reviews of computational procedures for process optimization (exemplified with sample computer programs) and of typical demonstrative experiments resulting in the net continuous conversion of H20 to H2 + ½02 (e.g. those of the Ispra-Euratom group) could have been included to illustrate recent advances. Turning to the important aspect of heat source, it is surprising that whilst the nuclear H T G R is emphasized as uniquely suited, there is hardly any reference to the adaptability of solar heat for TC water-splitting despite the impressive advances in this direction reported by the General Atomic Company of the United States. In logical sequence, the next three chapters relate to water-splitting processes employing light quanta, namely photochemical and photoelectrochemical conversions in inorganic and biological systems. Besides projecting the authors' own research, these chapters serve as good reference sources. In Chapter 8, Professor Akira Mitsui has outlined an excellent scheme for the utilization of marine algal and bacterial micro-organisms in the production of hydrogen and other valuable byproducts. In the introductory section of Chapter 6, the statement 'In a thermochemical water-decomposition cycle, the maximum attainable efficiency of energy conversion is limited by the thermal engine system that includes some endothermic reactions and at least one exothermic reaction' is misleading and opposed to the generally accepted theory of thermochemical cycles. It is well known that the Carnot engine limitation can apply only to the work involved in electrolytic steps, if any, product separation and inter-step transport of materials, and not to the chemical reactions per se.
Pergamon Press, Oxford, First edition 1979. xiii + 264 pp. Hardcover: (U.S.) $35.00.
Themes linking the most abundant energy-resource of the sun with the earth's most abundant material resource, namely water, to produce hydrogen have generated enormous interest among energy specialists because of the well-known and proven ideal fuel qualities of hydrogen, besides the environmental virtue of deploying solar energy to produce it from water. In recent years, there have been two notable documentations of the thoughts and technical implications of this concept. The first is the famous book of Professor J. O'M. Bockris, Energy: The Solar-Hydrogen Alternative, first published in 1975 and wherein a convincing case was made, firstly, for solar energy as the ultimate energy endowment for the survival of human civilization and, secondly, for hydrogen as the ideal 'carrier' of this energy. The second documentation is the recent publication under review. This work, which has been compiled by a very dedicated author and researcher in the field, Professor Tokio Ohta, focuses specifically on the experimental techniques for the dissociation of water by direct and indirect application of the sun's radiant energy. It is a logical and timely sequel to Professor Bockris's awakener book. A noteworthy feature of the new b o o k - - a feature which vindicates its claim as an 'authoritative review' of solar actuated watersplitting systems--is that each of its ten chapters has been written by specialists who have made significant contributions of their own to its title-topic. The first chapter, by Professor Ohta, is a synoptic outline of the book's scope. It contains a brief summary of the general characteristics of solar radiation and of the experimental methods of water decomposition elaborated in Chapters 3-8. Chapter 2 (also by Professor Ohta) provides the logical thermodynamic background to these processes. The third chapter (by Professor T. Takahashi) presents a balanced review of the theory and technology of water electrolysis, including the factors governing the efficiency of energy conversion and all the advanced types of water electrolysers that have been developed so far. However, the descriptions of the latter could have been enlightened with photographs of representative commercial versions. The schematic line drawings are poor substitutes as they fail to convey a proper impression of the plant's appearance. Further, considering the enormous amount of development research on water electrolysis technology carried out in Japan (the birthplace of this book), it is very surprising that there is hardly any reference to Japanese work in this chapter. 63
64
BOOK REVIEW
Chapter 9 differs from the preceding chapters in the sense that it relates, not to the production of hydrogen, but rather to the interaction of hydrogen with metals to form decomposable metal hydrides and the utility of the thermochemistry of this interaction for the storage of thermal energy and for some innovative thermomechanical applications employing hydrogen as the working fluid. The inclusion of this chapter is quite appropriate because of its practical implications for solar energy storage and heat-pump applications. Predominance of coverage is given to the current on-going research of the author on these topics to the virtual exclusion of more significant and more extensive work carried out in the U.S.A. and Europe, except for the one prime reference to the work of Gruen et al. of the Argonne National Laboratory. The last chapter (Chapter 10) is totally different from the preceding ones in that it does not concern in any manner the techniques of production and utilization of hydrogen as an energy vector, but stresses a labored plea for choosing marine locales for all kinds of solar energy games, including hydrogen production. Clusters of huge rotating floats are proposed for this purpose. On the authors' own showing (Table 10.1), the specific areal conversion of solar radiation works out to barely
Hydrogen Power: An Introduction to Hydrogen Energy and its Applications: by LAURENCE O. WILLIAMS.Pergamon Press Ltd., Oxford, 1980. ix + 158 pp. $29.00. The title of this book is quite fitting. Larry Williams, its author, has packed into 150 plus pages all that the layman would desire to know about hydrogen. The style is straightforward and interesting. Tables, charts, graphs and photos supplement the text nicely. Trivia buffs may find it lacking. There are few anecdotes. The author makes his statement in lean, concise terms. Only in the chapter on the physical and chemical properties of hydrogen does he slip off the deep end. Even then, however, his thorough knowledge of the subject and his ability to convey difficult concepts will help pull the reader through the more esoteric passages. The more complex material is necessary to show how much hydrogen is already a part of our daily lives. At the time the book was written, Mr. Williams was the Manager of Hydrogen Programs at the Aerospace Corporation in Germantown, Maryland, U.S.A. Although the book is comprehensive--he covers the history, properties, uses, production, transportation and storage, safety and energy carrier potential--it is not entirely objective. Sometimes the author's enthusiasm for hydrogen's prospects are not always muted.
10 W per m 2, which is roughly one-third to one-quarter of that achievable with land-based solar thermal-electric or photovoltaic conversion. Surprisingly, the technique of OTEC receives only brief mention, because according to the authors, OTEC is indirect solar energy conversion. The five appendices at the end of the book contain useful data regarding solar radiation, hydrogen, energy units and conversion factors, and general physical constants. Only a subject index is provided. The customary addition of an Author Index would have been very useful for quick spotting references. On the whole, this book is a highly useful source of information to those working in any area of solar energy conversion. To one who firmly believes that conversion to hydrogen is perhaps the most practical solution for massive (multi-megawatt scale) utilization of solar radiant energy on earth and the ultimate and lasting solution to the energy resource problem, this work is timely and welcome.
Energy Cell, University of Madras, Madras 600005, India
M. V. C. SASTRI
But I find this refreshing! It gives life to what some may consider just another textbook. The writer has conveniently placed pertinent bibliographic references at the end of each chapter, rather than at the end of the book, which is useful. He has also included a list of organizations involved in current research so that the reader, if he or she so desires, could follow up directly. Hydrogen Power gives an excellent overview of the many faceted element. The author provides, when necessary, the depth to make understanding of some applications and/or properties easier. The book has only seven chapters and their titles do not always convey their complete contents. Mr. Williams has covered every aspect of the subject and the inclusion of some material in a particular chapter is not in the least bit strained. For example, in the chapter, Hydrogen As an Energy Carrier, information about hydrogen's use in automobiles and aircraft is included. Technically these would be end uses rather than carrier applications but because of the book's brevity, a simple format is essential.
P.O. Box 362, South Lake Tahoe, CA 95705, U.S.A.
H. R. HINDS