Shower water warms Hamburg's heating systems

08.07.2025

Source: E & M powernwes

Hamburg Wasser and Hamburger Energiewerke are building a 60 MW wastewater heat pump at the Hamburg sewage treatment plant, which will supply up to 39,000 households with district heating from 2026.

Hamburg Wasser and Hamburger Energiewerke are currently building what they claim to be Germany's largest wastewater heat pump at the Hamburg sewage treatment plant. The two municipal companies, which have agreed to cooperate in 2022 to tap into previously unused energy sources, want to use the project to harness heat from treated wastewater. In future, the new large heat pump will supply up to 39,000 households with heat for heating and hot water via the district heating network of Hamburger Energiewerke.

The project is part of the so-called Port Energy Park, with which Hamburg intends to bundle various climate-friendly heat sources. According to Energy Senator Katharina Fegebank, the project is an important step for the heat transition in Hamburg. "As a heat source, the project will turn wastewater into a resource," said Fegebank during a tour of the construction progress on July 7.

Additional heat storage

The Hamburg sewage treatment plant collects all of the city's wastewater flows and, according to Hamburg Wasser, is an ideal location for the heat pump. Large quantities of treated wastewater with temperatures of at least 12 degrees Celsius are available there all year round. This initial temperature is significantly higher than the outside air in winter, allowing heat pumps to work more efficiently.

The new plant will heat the wastewater to up to 95 degrees Celsius. The hot water is then fed into the neighboring gas and steam turbine plant (CCGT) in the Hafen energy park. There, a large heat storage tank can temporarily store the heat. If required, the CCGT plant raises the temperature of the heat obtained further before it is fed into the Hamburg district heating network.

According to the companies, the installed capacity of the heat pumps amounts to a total of 60 MW distributed across four units, each with an output of 15 MW. The units work with four-stage turbo compressors, which are driven by motors with a nominal output of 6 MW each. The heat pump will process around 2.67 cubic meters of wastewater per second, which is roughly equivalent to 16 bathtub fillings.

The system will run for up to 5,000 full operating hours per year and, according to the company, save up to 90,000 tons of CO2. "With the new wastewater heat pump at the Hamburg sewage treatment plant, we as a municipal company are also making a contribution to the heat transition in the city," explained Michael Beckereit, Technical Managing Director of Hamburg Wasser. He emphasized that the previously unused wastewater heat could make an important contribution to the city's climate-friendly energy supply in the future.

Other heat sources in the network too

Hamburger Energiewerke is financing the new heat pump system with a good 60 million euros. They also pay an annual maintenance fee. In economic terms, this makes them the owners of the plant. Hamburg Wasser is responsible for planning, construction and operation, while Hamburger Energiewerke is responsible for controlling the system and feeding the heat generated into its district heating network.

"Large heat pumps are a key technology for the heat transition in Hamburg," explained Kirsten Fust, CEO of Hamburger Energiewerke. She pointed out that Hamburger Energiewerke intends to bundle various climate-friendly heat sources in the Hafen Energiepark in future and feed the heat generated into the city's grid under the Elbe.

The background to the project is the planned phase-out of coal-fired power generation by the Free and Hanseatic City of Hamburg by 2030 at the latest, and the Hafen Energy Park is a central component of this. Various climate-friendly heat sources such as waste heat from waste incineration plants, energy-intensive industrial operations or sewage treatment plant processes are to be integrated into the heat supply. The center of the energy park is the gas and steam turbine plant GuD Dradenau. According to Hamburger Energiewerke, it is due to go into operation at the end of 2025.

Author: Susanne Harmsen