Using internal heat from the earth as a source of power is called geothermal energy ("geo" meaning earth and "therme" meaning heat). The first 10 kilometers below the earth’s surface contain 50,000 times more energy than all the oil and natural gas resources in the world (Shere, 2013). People use this type of renewable energy to heat buildings, generate electricity and heat water. On a large scale, the electric utility/power grid industry utilizes it to run power plants.
Besides using the perpetual energy source to run power plants with steam produced by heated water, the earth’s energy can also be captured on a smaller scale using geothermal heat pumps, also known as ground-source heat pumps. The pumps use the year-round temperature of 50 to 55 degrees F that exists just a few feet below the ground’s surface. In general, a heat pump extracts heat and then transfers it.
Check out the various pump systems for harvesting geothermal energy.