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Geothermal

Geothermal energy involves the exploitation of different grades of thermal energy stored within the earth.

In certain geological areas, heat from deep within the earth’s interior can rise up to the surface. Whenever water enters fissures in this hot rock, it can become heated and can emerge on the surface as hot springs, or even as steam, creating features such as steam vents, geysers and hot mud springs. Alternatively, heated water can be trapped below the earth’s surface as a geothermal reservoir. This heat can reach temperatures of 400°C. It can be accessed by drilling to depths of over two miles.

Ground-source heat is a different form of geothermal energy. It is extracted from the low-temperature heat (10–20°C) that is found at relatively shallow depths within the earth’s crust. This source of heat remains at a relatively constant temperature all year and can be taken from the ground itself or from groundwater. Heat pumps can increase the temperature to provide a more useful output temperature of around 40–50°C, ideal for low-temperature heating systems like under floor systems and radiant panels.