This book represents a sincere attempt to present the concept of the solar hydrogen economy by Luther W. Skelton, Associate Professor in charge of the Environmental Studies Program at Sangamon State University in Springfield, Illinois. The author understands this concept extremely well; as he states: "The solar-hydrogen option is as yet little understood, but it has advantages which are positive enough to demand consideration. It offers the possibility of a creative, coherent, and positive high technology compatible with human energy needs and planetary survival."The book is meant for engineers and planners. It is not meant for a general audience, but it is written at a scientific level that would make it understandable by most people with a high school education and some technical bent.The book begins with an introduction that reviews our general situation with respect to energy, leading to the concept that no energy planning is safe for the future without consideration of the medium of energy needed and its relation to the environment. The next considerations are elementary, general concepts of matter and energy.The third chapter, also quite elementary, is concerned with energy in general, stressing renewable sources of energy. The chapter is particularly good in explaining wave power and ocean thermal energy conversion. Solar concentrators are discussed.Chapter 4 concerns hydrogen -biochemical conversion, photosynthesis, thermal and electrochemical conversion, and finally photoelectrolysis.

GaAs solar cells with conversion efficiencies as high as 14% at AM1 have been grown by the GaCl/AsH3 hydride technique. Thin (∼200 Å) layers of InGaP were used to passivate the GaAs top surface. We observe a 70-fold increase in photoluminescence intensity of the GaAs after passivation, which is consistent with a lowering of the GaAs surface recombination velocity from ≳106 to <104 cm/sec. Short-circuit current densities (Jsc) as high as 22 mA/cm2 and open-circuit voltages as high as 0.96 V were observed. (If achieved together, those values would yield an efficiency of almost 18%.) Voc was observed to increase directly with p-layer thickness (t), whereas Jsc decreased directly with t. The efficiency also increased as the zinc doping was decreased.

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