Geothermal energy is energy obtained from heat originating from the Earth's interior. Due to their high temperatures, magmatic intrusions and other areas with volcanic activity are zones with high geothermal potential. This type of energy can be used in thermal power plants, through a turbine whose blades are moved by water vapor produced by the Earth's heat. This rotational movement is transmitted to the shaft of generators, producing electricity. In Portugal, in the Azores Autonomous Region, there are electricity production units using geothermal energy. Besides being used for electricity production, geothermal energy is also used as a heat source for greenhouses or heat pumps, for thermal baths or industry, and for heating or cooling buildings.