Earth is endowed by nature. A few meters below the surface developed high temperatures ranging from 28 ° C and can reach, depending on the depth at 350oC. In some areas, either because of the volcanic soil or because of rising hot water from cracks, the heat of the earth is significantly larger than the surface, resulting in a relatively small depth to water or steam at high temperature. These areas are called geothermal fields, and there the exploitation of geothermal energy is appropriate. In Greece there are 56 hot springs. Somehow this explains the steam that came close to the Oracle of Delphi and gave inspiration to the Pythia. Even Thermopylae took its name from heat sources located in the subsoil. Since the temperature of the water or steam coming out of the earth depends on its usefulness. Milos and Nisyros in the heat of the water exceeds 90oC if drawn with a specific technology can generate electricity. In the effort made by the PPC to use the geothermal islands in 1985, creating a factory 2KW capacity for electricity generation, he found the reaction of residents complained about the stench caused by the release of gases. Missed opportunity to produce energy 120 KW, which arrives on the energy efficiency of all the Cyclades. The geothermal energy found at a depth of 100 meters can be used to heating and cooling buildings. The positive is that geothermal energy is not affected by climatic conditions and maintain constant temperature and constant flow. This method of heat pumps that carry water from the energy source is air-conditioned City Hall Rhodes and three homes. The cost of heating is cheaper by 50% from where anyone would use oil for heating. Geothermal energy is used to Macedonia and Thrace in greenhouses, fish farming etc. Although Greece has many reserves target for 2010 is to occupy 0.4% of energy from renewable having producing 12 KW.