Geothermal energy is the natural heat of the Earth. It is derived from the decay of the radioactive elements in the Earth’s crust and transferred to the subsurface by conduction and convection. The word geothermal comes from the Greek words geo (earth) and therme (heat).

For centuries, geothermal springs have been used for bathing, heating and cooking. But only in the early 20th century people have started to consider geothermal as a practical source of energy. Today Geothermal energy can heat, cool, and generate electricity: Geothermal energy can be used in different ways depending on the resource and technology chosen—heating and cooling buildings through geothermal heat pumps and generating electricity through geothermal power plants.

The exploitable geothermal resources are found throughout the world and are utilized nowadays in more than 80 countries.