Geothermal energy is produced from the internal heat of the Earth, especially when natural heat sources are near to the surface of the Earth. Energy is tapped from such natural heat sources by drilling into natural aquifers present and pumping out hot water or steam, forcing water through rock fractures at great depths of up to 8 kilometres. Resulting steam is then used to generate electricity. Geothermal energy is considered as a renewable energy source.
Over 20 nations use energy from natural steam. The Philippines produces one-seventh of its electricity from geothermal sources, and is an important energy source in other countries and areas, notably Iceland, northern California and parts of New Zealand. Parts of Southeast Asia, Central America and the western USA have a major geothermal potential. Southern Europe and East Africa have some notable sites.