Local utility company Stadtwerke Schwerin is now planning to put into operation the geothermal heating plant in the Lankow district of Schwerin, Germany by June of this year. This will be almost a year after the original date of commissioning of the plant, with delays caused by the high sediment content of the thermal fluids.

Plans for the Schwerin geothermal were first announced back in 2018. By the end of April 2023, an inauguration ceremony was held Chancellor Olaf Scholz and Minister-President Manuela Schwesig were in attendance to signal the start of operations of the heating plant.

The heating plant will utilize geothermal water pumped from 1300 meters depth, which initially at a temperature of 56 degrees Celsius. The heat is then transferred to an intermediate circuit before the temperature is increased using heat pumps. This is supplied to the district heating system by which it provides the heating needs of 2000 households, or about 15% of the district heating customers in Schwerin.

However, problems were encountered due to the presence of suspended particles in the fluids, likely from the sandstone formation. To prevent damage to the heat exchangers, a filter system had to be designed and integrated into the system. The exact type and size of the suspended particles had to be analyzed and considered into the filter system design.

With the filters now installed, the thermal fluid entering the heat exchangers meets the requirement for the equipment. The next step is to put the four heat pumps into operation. This has to be done gradually and under the guidance of the technicians of the manufacturing company, thus the June 2024 target.

A model for geothermal in Northern Germany

In November 2023, the “DeCarbSN” research project under the leadership of Georg-August University of Göttingen was announced which aims to comprehensively characterize the subsurface in the Schwerin urban area to aid in developing more geothermal district heating projects in northern Germany.

The project is being carried out in partnership with Stadtwerke Schwerin, Geothermie Neubrandenburg, and the Leibniz Institute for Applied Geophysics (LIAG) with funding by the Federal Ministry for Economic Affairs and Climate Protection (BMWK).

As part of the project, a digital reservoir model of the sandstone aquifer will be generated. The information gathered from the Schwerin geothermal heating project will provide excellent insight into this model. There are also 3D seismic surveys being planned for the spring of 2024.

The challenges encountered related to suspended particles in the Schwerin geothermal heating project provides valuable learnings for future geothermal projects in northern Germany. Once a viable solution has been found, similar filter systems can be integrated directly into future projects.