This is a comprehensive, fairly technical book about renewable forms of energy--solar, water, wind, and biofuels. The biofuels section covers biomass energy, agriculture, aquaculture, alcohol, methane, and wood. The focus is on small-scale systems which can be applied to the needs of the individual, small group, or community. More than one-fourth of the book is devoted to reviews of books and hardware sources. Hundreds of illustrations and a dozen original articles are used to describe the workings of solar water heaters, space heaters and dryers, waterwheels, windmills, wind generators, wood burning heaters, alcohol stills, and methane digesters. The final section of the book focuses on the need for energy conservation and some of the problems and potentials of integrated energy systems. (Author/BT)