After being initially extracted in the well house and losing temperature in the heat exchangers, the brine is on its way to the injection well at the Lankow Sports Park. Meanwhile, the now 56 degrees Celsius warm heating water from the thermal technology room is directed to the heat pump room.

Here, four high-performance heat pumps are installed, serving as the centerpiece of the first geothermal plant operated by the Schwerin utility company. This aspect gives the project its pioneering character because it marks the first nationwide implementation of high-performance heat pumps for utilizing medium-temperature brine for district heating production.

The four water-to-water heat pumps are connected in series, meaning the heating water passes through them one after the other. This process gradually increases the temperature of the district heating water in each pump until it reaches up to 82 degrees Celsius. This temperature is sufficient for the summer operation of the Schwerin district heating network. Simultaneously, the heating water is cooled down to about 18 degrees Celsius and then reheated in the heat exchangers.

A heat pump operates similarly to a refrigerator but in reverse. While a refrigerator extracts heat from its interior and releases it outside, a heat pump extracts heat from the heating water and transfers it to the district heating water. Inside a heat pump, a closed process consisting of four steps occurs, facilitated by a circulating fluid known as the refrigerant. Hence, the term "pump" in a heat pump. Evaporation, compression, condensation, and expansion – these four steps are undergone by the refrigerant, thereby increasing the temperature of the district heating water. In the Lankow facility, R1234ze is used as the refrigerant because it has a lower greenhouse gas potential, making it more environmentally friendly than other commonly used substances.

Externally, it's noticeable that one of the four heat pumps is smaller than the others. This difference is not merely visual but reflects a lower power output. The specific capacity of each heat pump, as well as the total capacity of their cascaded arrangement, has been tailored to the Schwerin utility company's facility and the temperature of the brine. Each of the three larger heat pumps has a heating capacity of about two megawatts, while the smaller one has slightly over one megawatt.

Electricity is required to operate the heat pumps and other equipment. This electricity is generated by two cogeneration units (CHP) located directly next to the geothermal heating plant. Each of these CHP units has an electrical capacity of 999 kilowatts, and their waste heat is also utilized. In the future, these two CHP units are planned to be operated with bio-methane, sourced from the Schwerin utility company's biogas plant at the Energy Site South after conversion. This integration will allow renewable geothermal energy to be transformed into green district heating for the state capital, Schwerin, using eco-friendly electricity.