Geothermal energy is thermal energy generated by and stored in the Earth. The Earth transfers about 40,000 GW of this heat to the atmosphere. Geothermal resources consist of thermal energy stored within the earth in rock, steam or liquid water. This energy source can be used indirectly for electricity generation, for directly heating buildings, baths, greenhouses and food processing. Geothermal power plants are typically 20-60 MW in size. Plant designs vary and are determined by local resource characteristics such as whether a well is dry or has geofluids present. Plant efficiency typically varies between 10-23% and depends on the reservoir temperature as well as the cooling system. Geothermal energy is an inexhaustible source of thermal and electrical energy on a human time scale. Its utilization is friendly to the environment and supplies base-load energy. Utilization of geothermal energy increases the regional and local net product. Electrical energy from geothermal resources can provide an important contribution to the base-load electrical energy supply.