Energy produced by the Earth's core can include both the heat beneath the surface of the earth (geothermal energy), available in the form of hot water or steam, and heat accumulated in surface waters (hydrothermal energy). The energy of the above waters is used for the production of district heat for municipal and agricultural production needs, and also production of electric power locally. Thermal waters and accompanying brine and healing waters can also be used for therapeutic and relaxation purposes (water pump rooms, swimming pools, thermal baths).
The use of heat from primary geothermal energy carriers through a heat exchanger, thus by using heat pumps, is not generally considered as renewable energy, regardless of the type of heat source: ground, air, surface water or geothermal basin.
The attractiveness of these sources is in features such as availability. This is because geothermal sources are not not effected by fluctuations due to weather and climate conditions. They are also a sources which are not subject of exhaustion. Moreover, they are neutral to the environment - geothermal energy does not release any harmful substances. What's more, geothermal technology devices do not take up much space and hardly change the appearance of the landscape.
Geothermal water, brine and healing waters can be found under the surface of almost 80% of the Polish territory. Despite such vast presence of such waters, their exploitation is not easy. The main obstacles are conditions of extraction and the financial side of this type of project.