How Geothermal Energy Works
Geothermal energy is a type of renewable energy that encourages conservation of natural resources. According to the U.S. Environmental Protection Agency, geothermal systems save homeowners 30–70 percent in heating costs and 20–50 percent in cooling costs compared to conventional systems. Geothermal systems also save money because they require much less maintenance, are highly reliable and are built to last for decades.
Heat from within the earth can be used as an energy source in many ways, from large and complex power stations to small and relatively simple pumping systems. This heat energy, known as geothermal energy, can be found almost anywhere and many regions of the world are already tapping geothermal energy as an affordable and sustainable solution. Even cold ground contains heat and below 10 feet the ground is typically about 55 °F. In moderate climates it may be extracted and used for home heating with a heat pump.
The largest group of geothermal power plants in the world is located at The Geysers, a geothermal field in California.The technology used to generate electricity from geothermal sources became popular in Sweden as a result of the 1973 oil crisis, and has been growing slowly in worldwide acceptance ever since. There has been a 20% increase in online capacity since 2005 and geothermal energy production is steadily growing.
For home applications geothermal energy is more practical for use from small wells or heat exchangers buried in shallow ground. Where natural hot springs are available heated water can be piped directly into radiators and used for home heating. If the ground is hot but dry, tubes drilled into the earth for heat exchange can collect the heat. But even in areas where the ground is colder than room temperature heat can still be extracted with a geothermal heat pump more cost-effectively and cleanly than by conventional furnaces. These devices draw on much shallower and colder resources than traditional geothermal techniques and they frequently combine a variety of functions such as solar energy and electric heating. Geothermal heat pumps use the steady temperatures just underground to heat and cool buildings cleanly and inexpensively.