geothermal energy

Energy extracted for heating and electricity generation from natural steam, hot water, or hot dry rocks in the Earth's crust. It is a form of renewable energy. Water is pumped down through an injection well where it passes through joints in the hot rocks. It rises to the surface through a recovery well and may be converted to steam or run through a heat exchanger. Steam may be directed through turbines to produce electrical energy. It is an important source of energy in volcanically-active areas such as Iceland and New Zealand. The Earth's internal heat is produced by the decay of radioactive substances in the rocks.