Geothermal energy

Geothermal energy is energy that comes from within the earth. It can be used both for the production of electricity and for the production of heat, including for heating purposes. To obtain it, it is necessary to drill holes. The technology that uses thermal energy from the ground are ground heat pumps, which can be used to heat the building and heat domestic hot water.

This energy is stored in soil, rocks and fluids that fill pores and rock crevices. It is constantly supplemented by the flow of heat transferred from the hot interior of the Earth to the surface, which is why it is inexhaustible. The heat in the interior of the Earth is partly primary heat from the formation of our planet and partly is heat from the decay of radioactive elements such as uranium, thorium and potassium. The temperature increases with depth, reaching even 6,000 degrees Celsius in the Earth's core.

Not everywhere can geothermal energy be used to the same extent. Its effectiveness depends on the geographical conditions, and more specifically geological conditions, related to, inter alia, with volcanic activity or infiltration of rainwater. The dimension of the so-called geothermal gradient, which is an indicator that describes the changes in the Earth's temperature with depth. For Poland, this parameter is approx. 32-33 ° C / km, and in the case of Iceland it is even 100 ° C / km.

Acquisition of geothermal energy is based on its extraction by means of boreholes several kilometers deep. For this reason, it is the most difficult renewable energy source to use, as it requires advanced technology and large outlays. However, the principle of operation itself is quite simple. Usually, two holes are made in the ground - one for taking hot water or steam, the other for "giving" the water back below the surface.

And now, most importantly, how can you generate electricity from hot water? In this case, the water extracted from the Earth's interior must have a much higher temperature and pressure than that which we can use to produce thermal energy. Water for electricity production can have as much as 460 ° C and a pressure of 30 bar, which is 30 times greater than that with which we are in contact every day! Water with such parameters is pumped out from under the surface and goes to the turbine, where some of its thermal energy is converted into mechanical energy. This energy is then transferred to a generator which converts it into electricity. After the energy is transferred, the deep water is returned to the ground. This completes the cycle.