The National Renewable Energy Laboratory projects that geothermal energy could provide the U.S. with an inexhaustible supply of energy for billions of years to come. This term, geothermal, comes from the Greek words geo (earth) and therme (heat). Hence, we're talking about literally drawing steam and hot water from inside the Earth as an energy source. Because heat is continuously produced inside the Earth, this resource is considered a renewable energy source. In the U.S., dozens of power plants are now harnessing this energy, and tens of thousands of homes are adding geothermal technology each year.
The slow decay of radioactive particles in the Earth's core, a process that happens in all rocks, produces geothermal energy, according to the U.S. Energy Information Administration (EIA). People can capture this energy to heat buildings and generate electricity. While geothermal energy is used in over 20 countries, the U.S. is the largest producer of geothermal energy in the world.
