Geothermal energy—created from Earth’s natural heat—has been used for thousands of years to cook and bathe. But modern technology has unlocked two main ways to harness geothermal potential. One produces electricity using hot water and steam locked underground. The other heats and cools buildings with a special form of heat pump.
America leads the world in geothermal power production, with about 3,080 megawatts of capacity from about 70 power plants, most of which are in Western states, according to the Geothermal Energy Association.
Then there are geothermal heat pumps. Unlike standard heat pumps, which exchange heat with the outside air, geothermal heat pumps rely on energy in the ground—the top 10 feet of earth remains around 50-60° Fahrenheit year-round—to move heat into and out of a building, providing winter heating and summer cooling.
These appliances come in two types: a groundwater system uses well, pond, or lake water; an earth-coupled model moves a liquid through underground pipes to disperse heat, which requires digging in a homeowner’s yard.
To help offset the expense, a federal tax credit equal to 30 percent of the cost for materials and installation applies to geothermal heat pumps through Dec. 31, 2016.
—National Rural Electric Cooperative Association