Another alternative energy book, this one appropriately compact, efficient, and relatively cheap. Halacy, a veteran science writer, presents a clear picture of the costs, risks, and benefits of exploiting the major non-fossil fuel or non-nuclear sources of power. These include the geothermal (hot springs, geysers, hot rocks), water (watermills or wheels, tidal power, sea thermal power), wind (windmills and more exotic wind machines), biofuels (methane or other combustibles derived from waste or active cultivation), and solar (solar thermal collectors, photoelectric cells, photochemical reactions). For each category Halacy summarizes historical developments and credits early inventors or men-ahead-of-their-times. On the whole he emphasizes currently planned or operational projects although he does not ignore some of the dream stuff (e.g., forests of windmills across the Great Plains, or a Mediterranean dam across the Strait of Gibraltar.) Halacy is ever the cautious optimist; he believes that currently existing alternative energy technology could solve our energy problems but only if government and industry move quickly and in the direction of multiple choices and flexible projects. One should think in terms of building a central solar power station for a small city, for example, and making use of the waste heat to supply homes with heat and hot water. An excellent job of reporting where we stand as well as where we should go.