Our earth's interior - like the sun - provides heat energy from nature. This heat, geothermal energy - yields warmth that we can use without polluting the environment. Geothermal is easy on the land and reliable because of the earth's constant temperature. Today, with geothermal heat pumps, we take advantage of this stable earth temperature - about 45 - 58 degrees F just a few feet below the surface - to help keep our indoor temperatures comfortable.