During 2025, geothermal technologies provided 0.2% of all energy consumed in the U.S. and 0.3% of all electricity. Geothermal energy is harnessed by transferring heat from or to the earth. The current main technologies include: (1) district heating systems, which heat buildings by piping in water from hot springs and reservoirs; (2) power plants, which generate electricity through turbines that are powered by steam or superheated water typically piped in from a mile or two beneath the surface of the earth; and (3) heat pumps, which cool and heat buildings by transferring heat to and from the ground. Electricity-generating geothermal plants are typically built at sites where geothermal reservoirs are not buried too deeply. In the U.S., such resources are mostly in the western states and Hawaii.