Giant sea-water heat pump in Denmark to warm up 25,000 residences

In a significant stride towards a greener future, large-scale heat pumps are transforming Germany's district heating sector. These innovative systems, operating in tandem with conventional boilers, are making a substantial impact, providing carbon-free heat to thousands of households.

The combined heating capacity of these heat pumps amounts to 70 MW, a significant figure that supports the integration of weather-dependent power generation like solar and wind. One such example can be found in Stuttgart, where these heat pumps are already in operation. Plans are underway to install similar systems in Berlin-Neukoelln, Mannheim, and Rosenheim, with all set to be operational by spring 2026.

Mannheim will be home to the largest river-based heat pump in the country, using water from the Rhine River to heat 3,500 households. Berlin-Neukoelln, on the other hand, will have a system that reaches around 55,000 connected households, with the heat from the pumps flowing back to the Neukoelln plant through a circulation system.

The city of Esbjerg, Denmark, has already successfully implemented two industrial-size heat pumps, providing heat to a city of 100,000 residents. Another heat pump under construction in Cologne, Germany, will have twice the capacity of the Esbjerg pumps.

The Danish pilot project demonstrates that large-scale seawater heat pumps utilizing the non-toxic natural refrigerant CO are technically possible and economically feasible. This technology is also being employed in the new German system in Berlin-Neukoelln, which is connected to several large-scale boilers and seven combined heat and power (CHP) units.

The German think tank Agora Energiewende argues that the entire heat demand in Germany up to 200 degrees can technically be covered by heat pumps. By 2045, large-scale heat pumps could provide 70% of the district heating supply and replace a very large proportion of the fossil gas used.

Hamburg will operate the largest and most innovative large-scale heat pump system in Germany, delivering around 200 gigawatt-hours of heat annually. The fuels used in Berlin-Neukoelln include fossil gas, wood pellets, hard coal, biomethane, and heating oil, but the shift towards carbon-free heat sources is evident.

As the new German government agrees that Germany should have more district heating, the expansion of these heat pump systems could be a promising step towards a greener future. The new technology in Berlin-Neukoelln also includes a planned CHP-powered air-cooling system and further potential heat sources like river water heat and geothermal energy.

Electrically driven heat pumps are considered able to replace conventional heating systems based on fossil fuels. With plans to generate half of Denmark's heat by way of electricity by 2035, district heating concepts are seen as a key measure for decarbonizing Germany's heating sector.

As these large-scale heat pumps continue to be installed and optimized, they are poised to play a crucial role in Germany's transition towards a more sustainable energy future. Mega-scale heat pumps, capable of ramping up from minimum load to maximum load in less than 30 seconds, offer flexibility that traditional systems lack. Approximately two to four kilometres of pipe are laid every year, extending the district heating network across a significant portion of the Neukoelln and Kreuzberg neighbourhoods. The potential is immense, and the future of district heating in Germany looks increasingly green.