Geothermal energy is derived from the natural heat of the earth.
The main source of this energy is the constant flow of heat from the earth s interior of the surface. The magma heats the surrounding rock structures and when underground water comes in contact with this heat, geothermal fluid is formed. A geothermal reservoir is a rock structure that contains geothermal fluid in the form of steam, hot water or a mixture of both. The generation of commercial electricity requires the extraction of large quantities of geothermal fluid. The quantity of the geothermal fluid required to continuously carry the energy to the surface.