28.08.23 | Updated on: 08.11.2023

Households in Hamburg’s Wilhelmsburg district will be supplied with climate-smart heat from a new geothermal plant from spring 2025. Researchers have now successfully completed the basic pumping tests for this. The Hamburg geothermal project is part of the living lab for the energy transition IW3 (Integrated Heat Turnaround Wilhelmsburg).

With their test results, those involved in the project have shown that it will be possible in future to pump thermal water with a temperature of 48 degrees Celsius from a depth of over 1,300 metres to the surface in Hamburg-Wilhelmsburg. Based on the pumping tests and the current planning of the geothermal plant, the research team is confident that a purely geothermal heat output of about 6 megawatts can be achieved. This would be sufficient to supply more than 4,700 households with heat. With the help of a planned multi-stage heat pump process, the number can be increased to more than 6,000 households.

Underground heat for the hot water circuit

Here, you can see how the pumping of the thermal water takes place in a closed, hydrothermal circuit.
©Hamburger Energiewerke
Here, you can see how the pumping of the thermal water takes place in a closed, hydrothermal circuit.

For this, the heat must come from underground into the residential buildings: after the thermal water is pumped through a borehole to the surface, heat energy is extracted from it with the help of a heat exchanger. This is then transferred to the hot water circuit and reaches the households via the Wilhelmsburg heating network. The water, which is finally cooled down,is fed back again and flows – through a second borehole – back underground, where it heats up again in the thermal water-bearing layer. From here, the cycle starts all over again.

Depending on the season, the hot water requires a different temperature level for district heating. To regulate the temperature level, the experts use a heat pump system. The researchers are planning a multi-stage process so that the thermal energy obtained can be further increased to supply the calculated more than 6,000 households.

Geothermal plant for a climate-smart heat supply for households

The project partners want to use the new geothermal plant to further expand the Wilhelmsburg heating network and thus support the heat transition. In the course of this, the two existing local heating networks are also to be connected, condensed, and expanded, creating a large district heating network.

The living lab for the energy transition IW3 is funded by the German Federal Ministry for Economic Affairs and Climate Action (BMWK) as part of the 7th Energy Research Programme. The project participants are pursuing the goal of supplying Wilhelmsburg's residential neighbourhoods with heat that is almost CO2-free.