The desire for renewable electricity has led to substantial increases in the global capacity to generate power from sources that are virtually emissions free. Yet most of those new facilities, specifically wind and solar projects, are dependent on an intermittent fuel source.Geothermal is powered by a constant supply of heat from the earth. It is able to run virtually all the time, day and night. It is not dependent on new technology (electricity has been produced from geothermal sources for more than 100 years) and the operating performance of a geothermal facility rivals the reliability of any other source of generation, renewable or not.

Geothermal electricity production in its simplest form relies on heat from the earth, the temperature of which generally increases with depth. The rate at which the temperature increases for a given unit of depth is referred to as the temperature gradient. Though the temperature gradient is on average about 2.5 degrees Celsius per 100 meters, there are places where the variation of this gradient can be substantial. The majority of these very high temperature gradient locations occur on the margins of the earth’s tectonic plates—the massive and moving pieces of the earth’s crust—where the upwelling of heat or the subduction of crust gives improved access to the enormous heat stored within the planet.

Geothermal energy is very much like traditional steam-fired power generation, but it substitutes the heat of the earth for the heat generated by the combustion of fossil fuels. In both cases, heat is used to produce steam which, in turn, is used to drive a turbine and generate electricity. Because the technology of steam turbines is extremely well known—mankind has more than a century of such experience—the operation of geothermal electricity facilities is highly reliable.

Follow the links below to learn more about geothermal energy.