The idea of using volcano energy raises an altogether different set of difficulties from those involved in present-day exploitation of other forms ofgeothermal energy in several parts of the world. To be utilizable by contemporary technology, the latter forms of energy must exist in an unusually favorable geological configuration, with an aquifer capped by an impermeable layer and heated from below. Such geological configurations are not common, as is attested by the relatively small number of productive thermal fields in the world. On the other hand, there are numerous active volcanoes, scores of them in Japan alone, that release tremendous amounts of heat. It has been a constant challenge to volcanologists to somehow harness that dissipated heat.