Geothermal Energy Basics

Geothermal energy is the heat from the Earth. This heat can be used for bathing, to heat (and cool) buildings, and to generate electricity.

The word geothermal comes from the Greek words geo (earth) and therme (heat). Heat is continuously produced inside the Earth. Geothermal resources can be found at different depths:

• Hot water or steam reservoirs deep in the Earth that are accessed or expanded by drilling
• Geothermal reservoirs near the Earth's surface, mostly located in the western United States, Alaska, and Hawaii
• The shallow ground near the Earth's surface that maintains a relatively constant temperature of 50-60°F.

This variety of geothermal resources can 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. Learn more about NREL's geothermal research.

Geothermal Applications

Heat Pumps

Geothermal heat pumps use the Earth's shallow ground temperature for heating and cooling.

Electricity Production

Geothermal electricity production generates electricity from the Earth's heat.

Direct Use

Direct use harnesses heat directly from hot water within the Earth.

Additional Resources

Geothermal News and Feature Stories

Geothermal Basics (U.S. Department of Energy)

Geothermal Technologies Office (U.S. Department of Energy)

Energy Kids: Geothermal Basics (U.S. Energy Information Administration)