Heating costs: Instead of gas: A heat source has remarkable potential

Berlin.
Scientists see huge potential for geothermal energy. How does heating with geothermal energy work – and what are the obstacles?

Even in times of political crisis, the residents of the Icelandic capital Reykjavík need not be afraid of a cold apartment in winter. Your heating is nourished by the earth itself. Hot springs feed the system.

This has also worked in some places in Germany for a long time. In Aachen, for example, buildings were heated with thermal water as early as 69 AD. Health tourists also appreciate thermal baths in south-west Germany. However, played as a replacement for gas heaters geothermal so far only a supporting role in most regions.

Geothermal heating: Researchers see huge potential in Germany

This could change soon. A research group from various Fraunhofer institutes and the Helmholtz Association, for example, is pushing for this. They recently launched a roadmap to increase the use of geothermal released. “The potential in Germany is of remarkable size,” says the report. According to the information, 300 terawatt hours of energy per year could be generated. This corresponds to a quarter of Germany’s heat requirements.

It would also be a boon for climate protection. Because more than half of the energy consumption is for the heat generation used. Only 15 percent of this has so far come from renewable sources.


Steep gas prices and fears of bottlenecks are increasing demand

So far, only a small proportion of households have covered their heat requirements with the almost inexhaustible energy from the depths. “The market is characterized by single-family homes,” says André Deinhardt, head of the German Geothermal Association. Around 400,000 systems are currently in operation in Germany.


The steep prices for gas and the threat of supply bottlenecks due to the war in Ukraine are causing demand to rise rapidly. “Customers are beating the companies up,” reports Deinhardt. A few years ago, companies still had to fight for every small order.

Geothermal energy: This is how heating with geothermal heat works

How geothermal energy works is easy to understand. The energy is in interior of the earth. The deeper you go in there, the higher the temperature. On average, it rises by three degrees Celsius every 100 meters. This heat is brought to the surface.

To do this, holes are drilled into the ground, depending on the method, between one and 5,000 meters deep. For example, warm water can be transported to the surface, the heat released there and pumped back again.

A heat pump converts the geothermal energy into thermal heat in the building or for district heating for many apartments. Conversely, it can also cool buildings on warm days. In the case of individual systems, the heat is usually recovered near the surface, usually at a depth of 100 meters.

Large systems, such as those used in Munich for district heating, sometimes go several kilometers deep into the ground. Munich is located on a large supply of thermal water. six geothermal power plants should supply the city completely with renewable district heating by 2040. Hamburg is also working on a climate-neutral supply heating energy. The system for the quarters in the Wilhelmsburg district is scheduled to go into operation as early as next year.

Costs: For whom is geothermal heating worthwhile?

Next to the Costs for the drilling and the material, electricity costs for the operation of the heat pump also have an impact. For homeowners, geothermal energy is now a worthwhile alternative to natural gas, explains Deinhardt. For a detached house with an annual consumption of 20,000 kilowatt hours, heating costs around 30,000 euros over a period of ten years, for a house close to the surface geothermal plant around 24,000 euros, with geothermal district heating even only 16,500 euros.

However, it is questionable whether this calculation by the association is still realistic today. Material bottlenecks or a lack of skilled workers as well as rising electricity prices are likely to make this investment more expensive. The development costs also vary from region to region. Some of the costs are subsidized by the state. the financial support could be increased significantly by the federal government this year – as part of the strategy against dependence on Russian gas.

What are the obstacles to geothermal energy in Germany?

Although known for a long time, the Expansion of geothermal energy still in its infancy. The approval authorities are not prepared for the onslaught of customers. “The authorities are overwhelmed,” observes Deinhardt. The geodata that provide information about the thermal potential or the formations in the subsoil are not even digitized.

Not every location is suitable for this. The potential is particularly large along the Upper Rhine Graben in south-west Germany, in the Ruhr area and also in north Germany. On the Upper Rhine beckons at the deep drilling another yield. Lithium is also brought to the surface with the water. The raw material is required to an increasing extent for battery production.

What are the dangers of deep earth drilling?

In Germany, according to the Federal Geothermal Association, in addition to the surface systems for single-family houses 42 large-scale systems for deep geothermal energy with a drilling depth of more than 400 meters are also in use: 30 of them supply heat, three provide electricity, nine systems both. The installed heat output was around 350 megawatts, the electricity output 47 megawatts.

However, “deep geothermal energy” also has its critics. Residents are afraid the technology could trigger earthquakes. In Switzerland, near the city of Basel, a geothermal project has already been stopped for this reason.


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