Geothermal Heat

**Geothermal energy** is thermal energy obtained from Earth's interior. Earth's internal heat comes partly from radioactive decay and partly from energy remaining from Earth's formation and internal differentiation.

Geothermal energy can provide: * direct heating; hot-water systems; electricity generation.

Earth's internal heat warms underground fluids. Hot fluid or steam can transfer energy to a turbine. The turbine drives a generator.

* can provide relatively steady energy; does not require fossil-fuel combustion during normal heat extraction; useful for heating and electricity.

* strongly location-dependent; * drilling can be expensive; underground fluids require management; geological and environmental effects must be considered.