Geothermal energy is heat energy that comes from the earth's molten interior deep in the earth's crust. The heat is brought near to the surface due to movements in the earth's crustal plates by intrusion of molten magma and by deep circulation of groundwater. Reservoirs of hot water under pressure are formed.
In some places geothermal energy rises to the surface in natural streams of hot steam or water, which have been used since ancient times for bathing and cooking.
Utilization of this geothermal energy is achieved by drilling wells into these reservoirs to bring such steam from the high pressure hot water, and direct the steam and separated hot water to drive turbines in power plants. The heat energy is thereby converted to electrical energy.