What is Geothermal?

Geothermal Energy Basics

Photo of a hot spring.

The Earth's heat—called geothermal energy—escapes as steam at a hot springs in Nevada.

Many technologies have been developed to take advantage of geothermal energy—the heat from the earth. This heat can be drawn from several sources: hot water or steam reservoirs deep in the earth that are accessed by drilling; geothermal reservoirs located near the earth's surface, mostly located in western states, Alaska, and Hawaii; and the shallow ground near the Earth's surface that maintains a relatively constant temperature of 50°-60° F.

This variety of geothermal resources allows them to be used on both large and small scales. A utility can use the hot water and steam from reservoirs to drive generators and produce electricity for its customers. Other applications apply the heat produced from geothermal directly to various uses in buildings, roads, agriculture, and industrial plants. Still others use the heat directly from the ground to provide heating and cooling in homes and other buildings.

Other geothermal resources exist miles beneath the earth's surface in the hot rock and magma there. In the future, these resources may also be useful as sources of heat and energy.

Other Resources

Geothermal Energy Technical Site
Idaho National Laboratory

Geothermal Technologies Program
U.S. Department of Energy

Geothermal Heat Pumps
EERE Consumer's Guide to Energy Efficiency and Renewable Energy



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