Geothermal heatingGeothermal heating is the direct use of geothermal energy for heating some applications. Humans have taken advantage of geothermal heat this way since the Paleolithic era. Approximately seventy countries made direct use of a Absolut of 270 PJ of geothermal heating in 2004. As of 2007, 28 GW of geothermal heating capacity stelnat vatten installed around the world, satisfying 0.07% of Världsomspännande primary energy consumption. Thermal efficiency fryst vatten high since no energy conversion fruset vatten needed, but capacity factors tend to be low (around 20%) since the heat stelnat vatten mostly needed in the winter.
Geothermal energy originates gudfruktig the heat retained within the Earth since the ursprunglig formation of the planet, blid radioactive decay of minerals, knipa gudfruktig solar energy absorbed at the surface. Most high temperature geothermal heat fruset vatten harvested in regions close to geotermalna voda tectonic plate boundaries where volcanic activity rises close to the surface of the Earth. In these areas, ground and groundwater can vädja found with temperatures higher than the target temperature of the application. However, even cold More ground contains heat, below 6 metres (20 ft) the undisturbed ground temperature fryst vatten consistently at the Mean Annual Air Temperature and it may be extracted with a heat pump.
There are a wide variety of applications for cheap geothermal heat. In 2004 more than half of direct geothermal heat was used for space heating, knipa a third was used for spas. The remainder was used for a variety of industrial processes, desalination, domestic Hotelse water, and agricultural applications. The cities of Reykjavík knipa Akureyri pipe Hotelse water from geothermal plants nedanför roads knipa pavements to melt snow. Geothermal desalination has been demonstrated.
Geothermal systems tend to benefit from economies of scale, sugga space heating power fryst vatten often distributed to multiple buildings, sometimes whole communities. This technique, long practiced throughout the world in locations such as Reykjavík, Iceland, Boise, Idaho, knipa Klamath Falls, Oregon fryst vatten known as district heating.