Wastewater provides heat for Pfaffenhofen

09.05.2025

Source: E & M powernews

In future, the municipality, municipal utilities and Danpower will use heat from wastewater to provide a climate-neutral supply in Pfaffenhofen. The new northern combined heat and power plant is due to start in 2026.

The town of Pfaffenhofen an der Ilm (Bavaria) wants to tap into a new source of climate-friendly heat: in future, as the utility company near Munich announced in a press release, purified wastewater from the nearby sewage treatment plant will be used to supply district heating. To this end, it plans to commission two large heat pumps in the planned northern combined heat and power plant in the immediate vicinity of the sewage treatment plant from the second half of 2026. The project is part of the local climate protection strategy, with which Pfaffenhofen aims to become climate-neutral by 2035.

Danpower Biomasse GmbH, a subsidiary of energy supplier Danpower from Potsdam, is responsible for the planning, construction and operation and is fully financing the project. The heat pumps extract thermal energy from the treated wastewater, which is discharged into the Ilm after treatment. At a flow rate of around 100 liters per second, the water is cooled by up to 8 degrees Celsius on average. In future, this energy will provide up to 50 percent of the heat required by the new combined heat and power plant.

The thermal energy generated will not only be fed into the existing district heating network, but will also supply a large industrial company in Pfaffenhofen. In this way, the city, municipal utilities and Danpower are making a further contribution to the decarbonization of the municipal energy supply.

The city council approved the cooperation agreement with Danpower in April. According to the city administration, this contract contains clear climate protection requirements: For example, the large heat pumps must be operated exclusively with green electricity.

Heat recovery with double benefits

Technically, heat recovery takes place via a closed intermediate circuit, which extracts thermal energy from the treated wastewater - also known as clean wastewater. After cooling, the water is discharged into the Ilm. The lower temperature reduces the warming of the river in summer - a side effect that also improves the ecological quality of the water, according to the municipal utilities.

The project fits seamlessly into the overall concept for the energy transition in Pfaffenhofen: the city and its municipal utilities want to further expand the district heating network and gradually switch to a completely climate-neutral heat supply. Danpower Biomasse GmbH, which operates the district heating network, will also take over the long-term operation of the northern combined heat and power plant in addition to the investment.

Author: Davina Spohn