Deep geothermal energy
The Earth is a considerable source of energy. The use of geothermal ground heat dates back thousands of years. Today, it is mainly used to heat and cool buildings, either directly through district heating systems or indirectly through heat pumps, in the case of very low temperature resources (under 30°C). It can also be used for certain industrial processes. There are various types of geothermal energy (very low, low, medium and high temperature) which are categorised in accordance with the purpose for which the energy is used (heat, electricity, cogeneration).