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Geothermal energy is thermal energy extracted from the Earth's crust. It combines energy from the formation of the planet and from radioactive decay . Geothermal energy has been exploited as a source of heat and/or electric power for millennia.
Geothermal energy is a type of renewable energy that encourages conservation of natural resources. According to the US Environmental Protection Agency , geo-exchange systems save homeowners 30–70 percent in heating costs, and 20–50 percent in cooling costs, compared to conventional systems. [ 29 ]
Geothermal power is considered to be a sustainable, renewable source of energy because the heat extraction is small compared with the Earth's heat content. [7] The greenhouse gas emissions of geothermal electric stations average 45 grams of carbon dioxide per kilowatt-hour of electricity, or less than 5% of those of conventional coal-fired plants.
The evolution of Earth's radiogenic heat flow over time. The radioactive decay of elements in the Earth's mantle and crust results in production of daughter isotopes and release of geoneutrinos and heat energy, or radiogenic heat. About 50% of the Earth's internal heat originates from radioactive decay. [17]
Earth cutaway from core to exosphere Geothermal drill machine in Wisconsin, USA. Temperature within Earth increases with depth. Highly viscous or partially molten rock at temperatures between 650 and 1,200 °C (1,200 and 2,200 °F) are found at the margins of tectonic plates, increasing the geothermal gradient in the vicinity, but only the outer core is postulated to exist in a molten or fluid ...
A heat pump in combination with heat and cold storage. A ground source heat pump (also geothermal heat pump) is a heating/cooling system for buildings that use a type of heat pump to transfer heat to or from the ground, taking advantage of the relative constancy of temperatures of the earth through the seasons.
Geothermal power is a renewable energy source that uses the Earth's internal heat to produce electricity and heat water. One-hundred and fifty megawatts is roughly enough electricity to power ...
DX system being drilled in the 1980s. A direct exchange (DX) geothermal heat pump is a type of ground source heat pump in which refrigerant circulates through copper tubing placed in the ground unlike other ground source heat pumps where refrigerant is restricted to the heat pump itself with a secondary loop in the ground filled with a mixture of water and anti-freeze.