Kids Research Express

Geothermal Energy, energy contained in intense heat that continually flows outward from deep within Earth . This heat originates primarily in the core . Some heat is generated in the crust , the planet’s outer layer, by the decay of radioactive elements that are in all rocks. The crust, which is about 5 to 75 km (about 3 to 47 mi) thick, insulates the surface from the hot interior, which at the core may reach temperatures from 4000° to 7000° C (7200° to 12,600° F). Where the heat is concentrated near the surface, it can be used as a source of energy. Topics: Geothermal Geology Geothermal Reservoirs Geothermal Power Plants Direct Use of Geothermal Water Geothermal Energy and the Environment Outlook for Geothermal Energy

. Geothermal energy is a renewable resource: Earth’s heat is continuously radiated from within, and each year rainfall supplies new water to geothermal reservoirs. Production from individual geothermal reservoirs can be sustained for decades and perhaps even centuries. Compared to other types of power plants, geothermal plants have relatively little effect on the environment. Geothermal power plants have been successfully operated in farm fields, in sensitive desert environments, and in forested recreation areas. Hydrogen sulfide gas , which can be toxic at very high concentrations, is sometimes present in geothermal reservoirs. However, this gas is removed from geothermal water with antipollution “scrubbing” equipment. Geothermal reservoirs contain higher concentrations of minerals and chemicals than do aquifers used for drinking water. Therefore, wells drilled into geothermal reservoirs have several layers of pipes, or casing, cemented into the ground nearly the entire length of a we...