Geothermal energy

Geothermal energy is one of the cleanest and most reliable renewable energy sources. It provides heat that originates in the melted core of the Earth, deep below the Earth’s crust. The heat is transferred to the surface as a result of the movement of tectonic plates by penetration of molten magma and deep circulation of ground waters and reservoirs of hot water under big pressure from the formation of Earth. Similar to solar and biomass energy, this energy may be used for the production of several types of energy: electric energy and thermal energy in the form of vapours which is converted to thermal energy. At higher temperatures, it is also possible to use it for the production of electric energy. The region of Central Europe, and the Slovak Republic in particular, belong to the regions with increased occurrence of this type of energy.

Geothermal power plants are divided into:

• Plants with overheated vapours – vapours coming out directly from the drill hole, powering the steam turbine with a generator after separation of water. Their output does not exceed 3 MW.
• Plants with hot water – in expander the geothermal water with high pressure and temperature is converted to wet vapours which power the steam turbine with a generator.
• Binary-cycle plants – in an exchanger, the geothermal water with temperatures above 130 °C heats liquid with low boiling point whose vapour powers the expansion turbine connected with electric energy generator.
• Geothermal energy has large potential, but implementation of these kinds of projects is very demanding in terms of funds, time and technologies. Compared to other RES (wind or solar energy), geothermal energy is much more reliable and stable in terms of transmission network stability.