Near surface and deep geothermal energy
Definition: What is “geothermal energy”?
Geothermal energy is ground heat stored in the earth's crust. Ground heat tapped by means of geothermal drilling can be used as regenerative energy for heating, cooling, the generation of electricity and geothermal generating plants (cogeneration).
Near-surface and deep geothermal energy
With near-surface geothermal energy, ground heat from a depth down to approximately 400 m is extracted from the soil, rock or groundwater and used for heating and cooling homes and facilities, usually by means of a heat pump.
Deep geothermal energy
Deep geothermal energy involves deep drilling more than 400 m below the earth’s surface. One differentiates between petrothermal deposits and hydrothermal deposits.
In a petrothermal deposit, heat is stored in hot intrusive rock. Here heat extraction is usually performed by means of stimulation and a type of heat exchanger system – the EGS (enhanced geothermal system).
In a hydrothermal deposit, heat is mainly stored in water.
In case of deep geothermal energy, one also differentiates between low-enthalpy deposits and high-enthalpy deposits..
Low-enthalpy deposits are defined by a relatively low temperature.
The term high-enthalpy refers to deposits with high temperatures, allowing electricity to be generated with a high efficiency factor using steam turbines.
Geothermal energy is an energy source that can be used over the long term. In theory, it could cover the worldwide demand for energy over a period of 100,000 years. Ground heat is environmentally friendly, renewable, geothermal energy from the depths of the earth.
Geothermal systems in Germany
There are and were geothermal systems in Germany, e.g. in: Geretsried, Landau, Unterhaching, Laufzorn, Bruchsal, Brühl, Dürrnhaar, Groß Schönebeck, Neustadt-Glewe, Schaidt, Bad Urach, Offenbach an der Queich, Mauerstetten, Riedstadt, Speye, Simbach-Braunau, Sauerlach, Kirchstockach, Kirchweidach, Traunreut, Taufkirchen, Holzkirchen, Weilheim, Bernried.