Geothermal energy comes from the heat stored in the Earth’s core, about 4,000 miles/ 1,609 kilometers below the surface, and heat from the sun warming the Earth. The word geothermal originates from the Greek words geo (earth) and therme (heat).
The ground is a good insulator and stores the heat as energy. Pipes are run through a large area several feet underground. Water is heated as it passes through these pipes. New drilling technologies are being researched and developed to capture the heat in deeper areas.
How Geothermal Energy is Formed
Magma (layers of melted rock from the Earth’s crust) deep in the Earth’s core heats nearby rock and rainwater that has seeped into the ground. Some of this hot water reaches the Earth’s surface in the form of geysers or hot springs. But most stays trapped in porous rocks and cracks underground in what are called geothermal reservoirs.
Geothermal specialists drill into these reservoirs to access the hot water and steam and use it to generate electricity at geothermal power plants. The heated water and steam produces enough power to spin turbine generators that make electricity.
Geothermal heat pumps use the Earth’s relatively stable underground temperature to heat and cool buildings with very little energy use or environmental impact. The pumps, which use pipes buried next to buildings, circulate water or other liquids to either heat the buildings using energy from the Earth’s crust or cool the buildings by pulling heat from them and transferring it to the Earth.
This form of heating and cooling is used in the US, Sweden, Romania, Japan and other countries around the globe.