Power obtained by using heat from the Earth's interior.
Most geothermal resources are in regions of active volcanism . Hot springs, geysers, pools of boiling mud, and fumaroles are the most easily exploited sources. The ancient Romans used hot springs to heat baths and homes, and similar uses are still found in Iceland, Turkey, and Japan. Geothermal energy's greatest potential lies in the generation of electricity. It was first used to produce electric power in Italy in 1904. Today geothermal power plants are in operation in New Zealand, Japan, Iceland, Mexico, the U.S., and elsewhere.