Geothermal energy has been used for domestic heating for centuries in countries around the world such as Italy and Iceland. Today this energy is paired with heat pumps for warming houses, used for district heating and for the generation of electricity. The largest geothermal electric facility in the world, at the Geysers in Northern California, started operation in 1960.

In a typical geothermal power plant a well is first drilled to tap the geothermal reservoir beneath the earth's surface. The hot liquid is then extracted by means of natural forces or pumping, then the heat in the liquid is used to produce steam in a flash chamber or heat exchanger. The steam drives a turbine generator that produces electricity, and the spent liquid is re-injected into the reservoir. Geothermal power plants supplied over 40 billion kilowatt hours of electricity in 1998.

Browse our glossary of renewable energy terms or our list of geothermal organizations for more information.

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