Geothermal energy is heat energy from the earth—geo (earth) + thermal (heat). Geothermal resources are reservoirs of hot water that exist or are human-made at varying temperatures and depths below the earth's surface. Wells ranging from a few feet to several miles deep can be drilled into underground reservoirs to tap steam and very hot water that can be brought to the surface for use in a variety of applications such as electricity generation, heating and cooling and direct use( U.S. Dept. of Energy).
