As you descend deeper into the subsoil and the Earth’s crust, underground rock and water become hotter. This heat is referred to as geothermal energy, and can be recovered at various depths and temperatures using a range of techniques. It represents a renewable energy source that can heat – or cool – houses, apartment blocks, factories and farm buildings. If used to drive a turbine, the heat can also be converted into electricity.

Very low-temperature geothermal energy can be recovered from heat sources under 30°C located at depths of up to 200 meters below the surface. As the temperatures are not high enough for direct use through a heat exchange system, additional processing via heat pumps is needed to increase them to a level sufficient for heating. This type of energy is used in single-family homes, apartment blocks and commercial buildings.

The Earth’s heat is a source of energy that has been used since ancient times.