Energy derived from the earth's volcanic interior, for instance, from hot springs, geysers, or heat energy in subsurface strata. In theory this is a virtually inexhaustible source of energy because the heat is derived from the pressure of overlying strata. In practice, it is difficult to extract and use. Iceland is a model of how it can be done: geothermal power supplies the nation's needs for heating domestic and public buildings, but similar methods are not always feasible. As a source of energy, geothermal power has a great advantage in being nonpolluting.
Subjects: Public Health and Epidemiology.