Geothermal energy is actually renewable. In fact it comes from the hot core of the Earth, which has a temperature of over 4000 ° C. Because of the inexhaustible supply, however, these resources must follow. On the surface it gets through volcanic fissures in the rocks. It is the oldest energy on the planet, and is generally considered a clean source of zero environmental consequences (in terms of greenhouse gas emissions). This statement is not entirely true. Steam-water mixture from the geothermal It contains dissolved gases, particularly carbon dioxide CO2, H2 S, CH4 methane and ammonia NH 3. In comparison to other sources, however, emissions per unit of energy produced statistically significantly lower. Geothermal energy is therefore environmentally better alternative.
Inside the Earth accumulates a large amount of energy said. The slow penetration of the surface of the thermal flows are formed, which amount to an average of 0.063 W / m2. The thermal gradient measured temperature increase per unit length: near the surface of the earth is a thermal gradient that drives the geothermal heat flux, approximately equal to 30 ° C / km. Thus, the about 3 km length to average 100 ° C. These data suggest that the resulting performance is very high, but it is spread over such a large area that its density is very low. It is much lower than the density of heat flow that comes from the sun in clear weather. This makes the use of this energy is difficult, but in regions with unusually large geothermal sources is geothermal gradient greater than average. Such place can be found at a depth of 2500 m and 1500 up to a temperature of 200 ° C.
In Slovakia there are 25 prospective areas of geothermal resources with temperatures up to 150 ° C at depths up to 5000 m. Currently used for heating hospitals, housing estates and operation of swimming pools. As the most promising site in view of its potential appears Košice basin, in which the underground geothermal water at 120 to 160 ° C, at a depth of less than 3000 m. Unfortunately, it is now being used in the Slovak Republic is, however, limited due to high costs. The advantages of geothermal energy are high power, no production of pollutants and the ability to position anywhere on the mainland. The disadvantage is that the use of that energy increases the number of earthquakes, fall through the Earth’s crust and the risk of leakage of toxic compounds from the well.
The first geothermal power generator tried Piero Ginori Conti prince in 1904 in the village of Larderello in Italy. The most important user of geothermal energy in the world is Iceland, where more than 85% of apartments are heated geothermal energy and 44% of total energy consumption covers just from geothermal sources. The greatest amount of power using this type of energy is located in California, USA, a leading manufacturer of electricity from geothermal sources as well as the Philippines, Mexico, Italy, Japan, Indonesia and New Zealand.
Although Sweden has no volcanoes, geysers, or deep hot aquifers, surface geothermal energy use has spread through heat pumps that can be installed almost anywhere. This is also true for Germany, Austria and Switzerland, the market is currently being developed as well as in France and the Benelux countries.
Geothermal energy is used in various fields such as electricity, the network of central heating or individual systems – geothermal heat pumps, further heating of greenhouses, fish farming and seaweed production (spirulina), drying processes in agriculture, agropotravinársvo, timber industry and form. It also finds application in projects of desalination of sea water on Greek islands. French caviar from Mios (Aquitaine) or Greek asparagus from Xanthi owe their existence to just geothermal energy. In basins with deep aquifers, such as in Hungary or France, and in areas with hot springs, geothermal technology can benefit at different temperatures.