Geothermal energy refers to the utilisation of thermal energy stored in the earth's crust, which is used for heating and cooling as well as for generating electricity. While geothermal energy is primarily known in Scandinavian countries such as Iceland, it is also used in a wide range of applications in Germany. With an average temperature rise of around 3 Kelvin per 100 metres depth, geothermal energy opens up different temperature levels and therefore offers a wide range of possible applications.

There are two main types of geothermal energy: near-surface geothermal energy and deep geothermal energy. Another form of geothermal energy is geothermal collectors. Geothermal collectors are a specific technology of near-surface geothermal energy and consist of plastic pipes laid horizontally in the ground. Just like geothermal probes, they are used as a heat source for heat pump heating systems.

The two main types differ fundamentally in their depth of utilisation, the temperatures that can be reached and the resulting application possibilities. Near-surface geothermal energy is mainly used for individual buildings, while deep geothermal energy enables larger projects such as district heating networks or electricity generation

Near-surface geothermal energy

• uses the subsoil to a depth of approx. 400 metres (depending on the country and federal state)
• Reaches temperatures of up to 25 °C
• is primarily used for heating and cooling buildings, for hot water preparation in residential and commercial buildings, for technical systems or infrastructure facilities.

Deep geothermal energy

• uses heat from depths of 400 metres up to 5,000 metres
• Temperatures are typically between 60 °C and 100 °C
• Can be used to generate electricity, for industrial processes and to supply district heating networks

Geothermal collectors

• installed at a shallow depth in the ground (typically 0.8-1.6 m)
• the flow temperature is typically around 0°C
• are suitable for use in heat pump systems for heating and hot water preparation in residential and commercial buildings (a frost-proof brine is required)

Advantages of geothermal energy

Geothermal energy has several advantages over other energy sources:

• Environmentally friendly: Compared to fossil fuels, geothermal energy is significantly more environmentally friendly
• Inexhaustibility and availability: The energy source is practically inexhaustible and available almost everywhere and at all times, regardless of the seasons and climate
• Low carbon footprint: the carbon footprint of geothermal energy utilisation is low
• Versatile: Geothermal energy can be used for power generation, heating, cooling and supplying district heating networks