Today, about four percent of the energy used in the United States comes from geothermal sources, mostly in the western states.
Geothermal energy comes from the heat within the earth, and is used to make electricity.
People have used geothermal energy for thousands of years. Hot springs have often been used for bathing, and some believe these springs have healing powers. Geothermal heat pumps are used to heat and cool homes and public buildings because the power source can reduce conventional heating costs up to 70 percent and cooling costs up to 40 percent. Some scientists think that someday we will be able to capture the energy in volcanoes, the ultimate geothermal resource.