Geothermal energy is the heat produced deep within the Earth's core. Geothermal energy is a clean, renewable resource that can be used for use as heat and electricity. Geo means “earth” and thermal means “heat” in Greek. The word geothermal comes from the Greek words geo (earth) and therme (heat).
Geothermal energy is a renewable energy source because heat is continuously produced within the Earth. People use geothermal heat to bathe, heat buildings and generate electricity. According to the Geothermal Research Council, geothermal energy is (thermal) heat derived from the earth (geo). Geothermal energy comes from the Earth's heat.
The word geothermal comes from the Greek words geo, which means earth, and therme, which means heat. People all over the world use geothermal energy to produce electricity, heat buildings and greenhouses, and for other purposes. Geothermal energy is considered a renewable resource. Land-based heat pumps and direct-use geothermal technologies are used for heating and cooling applications, while deep and improved geothermal technologies generally take advantage of a much deeper and higher temperature geothermal resource to generate electricity.
Depending on its characteristics, geothermal energy can be used for heating and cooling or used to generate clean electricity. The majority of people in Iceland and more than 500,000 people in France use geothermal heat for their public buildings, schools and homes. Technologies for direct uses, such as district heating, geothermal heat pumps, greenhouses and other applications, are widely used and can be considered mature. In addition to internal heat flows, the top layer of the surface, at a depth of 10 m (33 ft), is heated by solar energy during the summer and releases that energy and cools during the winter.
According to most official descriptions of the use of geothermal energy, it is currently called renewable and sustainable because it returns an equal volume of water to the area where heat is extracted, but at a slightly lower temperature. The first recorded case of using geothermal heat to produce electricity was in Larderello (Italy) in 1904. Geothermal water was used to help grow plants in greenhouses and for district heating in homes and businesses. Water from direct geothermal systems is hot enough for many applications, such as large-scale pool heating; space heating, cooling and hot water on demand for buildings of most sizes; district heating (i.e. Prince Piero Ginori Conti tested the first geothermal energy generator on July 4, 1904, in the same Larderello dry steam field, where it began the extraction of geothermal acid).
In 1892, the first district heating system in the United States in Boise, Idaho, ran directly on geothermal energy and was copied in Klamath Falls, Oregon, in 1900. The world's oldest geothermal district heating system in Chaudes-Aigues, France, has been operating since the 15th century. As noted above, the cost of drilling is an important component of a geothermal power plant budget and is one of the main barriers to the further development of geothermal resources. The initial construction costs of geothermal power plants are high because wells and geothermal power plants must be built at the same time.
The heat pump circulates a heat-carrying fluid, sometimes water, through pipes to move heat from one point to another.