Making Geothermal Projects Work. The core of the Earth is kept hot by radioactive decay while the surface is kept warm by solar radiation. Geothermal “energy” is extracted from the depths of the Earth while geothermal heating and cooling (now called geoexchange) is extracted from the surface of the Earth. This is why we refer to the Earth as our free solar energy storage system from which we can exchange low level energy at will.
