Is the floor temperature warmer than air

Energy from the ground

Electricity and heat directly from memory. The geothermal energy can be used in many ways.

What is geothermal and geothermal energy?

The inside of the earth has a temperature of several thousand degrees. Volcanoes and geysers are spectacular evidence of the hot interior of the earth. This geothermal energy comes partly from the time the earth was created, partly from radioactive decay processes in the earth's interior. Geothermal or geothermal energy is therefore one of the regenerative energies. However, mostly it is not the energy flowing in from the earth's interior that is used, but the energy stored in the earth's crust. This means that part of the earth's body (or soil) cools down over several decades.

The heat stored in memory can be used both directly, for example for heating and cooling in the heating market (heat pump heating), as well as for generating electricity or in a combined heat and power system. Regardless of the season, wind or sun, geothermal energy is a permanent, uniform and abundant source of energy.

Classic use of geothermal energy and deep geothermal energy

In the top 10-15 meters, the soil temperature is determined by atmospheric factors such as solar radiation, air contact and seeping rainwater. Below that, down to a depth of around 50 meters, the temperature is constant at around 10 ° C throughout the year. Below 50 meters, the temperature rises by an average of 3 ° C per 100 meters due to the influence of the heat flow from the earth's interior. The average temperature at a depth of 5,000 m is 160 ° C.

Depending on the depth of use, a distinction is made between near-surface geothermal energy and deep geothermal energy. The limit here is 400 m and a temperature of more than 20 ° C. Often, however, geothermal energy is used in conjunction with heat pumps for heating and cooling buildings as well as for hot water preparation from a significantly lower depth.

Near-surface geothermal energy - energy supply despite low temperatures

Even the top 100 meters in the ground are suitable for generating energy. Temperatures of a maximum of 12 ° C prevail here, but these are constant regardless of the time of day and time of year.
These relatively low temperatures can be increased to the 35 to 55 ° C required for heating purposes with heat pumps. The near-surface geothermal energy is used in individual systems for heating and hot water supply or also for cooling one- and two-family houses.

A distinction is made:
Geothermal collectors are laid at a shallow depth. This requires an excavation of around 1 meter. However, these collectors are being laid across the board. For a heating power of about 6kW an area of ​​about 300m / 2 is required. However, soil moisture, for example, is relevant for the actual amount. If the floor is damp, the heating output will increase over the same area.

Geothermal probes are set by drilling up to 200 meters in the ground. These holes have a diameter of 50 cm to 60 cm. Depending on the geological conditions, the depths and the boreholes can be different.

Deep geothermal energy - the earth as a water heater

Geothermal energy from boreholes from approx. 400 m is called deep geothermal energy. Geothermal energy can be developed through deep boreholes, which can be used directly, i.e. without heat pumps. With new processes such as the "hot-dry-rock process", rock layers at a depth of 4,000 to 5,000 meters are used as a kind of instantaneous water heater. Water is pressed into crevices in hot rock layers at high pressure. There it heats up, is conveyed to the surface and then used for large-scale heat supply / power generation. The cooled water is then returned to the subsoil.

Areas of particular interest for geothermal energy are those where several hundred degrees can be reached even at a shallow depth. Such conditions are often linked to volcanic activity. In geothermal energy they are considered high enthalpy deposits. They are used worldwide to generate electricity. This is ideal in several places in Iceland, so the country gets a large part of the heat it needs from geothermal energy. In Germany, these are primarily the North German Basin, the South German Molasse Basin or the Upper Rhine Rift.