The earth’s thermal energy is created by the decay of radioactive elements in the earth along with the heat from the sun and that remaining from the earth’s creation. Unlike solar power or wind power, geothermal energy is not interrupted by lull times. The technology also has a small carbon footprint in development.
The heat from geothermal energy can be (and is) used either directly to heat homes and businesses or used in conjunction with geothermal heat pumps. In the same way that they can be used to heat, geothermal systems can also be used to cool. In a hotter environment, or at a hotter time of year, water circulated through a geothermal loop carries heat below the earth’s surface, where it is absorbed into the ground; the cooled water is carried back up to regulate the higher ambient temperature. Geothermal heat pumps are one of the environmentally-friendly methods used to cool green data centers.
Geothermal energy can also be used to drive steam turbines. One example of this technology is Calpine Corporation’s geothermal plants in the Mayacamas Mountains in northwestern California. These 15 plants produce up to 725 megawatts daily, making them the largest geothermal energy source in America.
Enhanced Geothermal Systems (EGS) are one of the technologies being developed in this field. EGS uses deeper wells with methods or drilling, much like those used in hydraulic fracturing. Unfortunately, as with hydraulic fracturing (sometimes known as "fracking"), EGS also has the potential side effect of causing earthquakes.
See a video demonstration of a geothermal plant: