Relics of the past still stand on the site of the Schöneweide thermal power plant on the southeastern edge Berlin. Dark blue steel structures and cranes rise up, a conveyor belt stretches from the banks of the Spree to the boiler house. For decades, tons of coal ran along the belts here to heat water and feed it into the approximately 180 kilometer long district heating network of Berlin’s second largest heat supplier BTB. For warm living rooms and hot showers in the capital.

This has been over since spring 2025. Coal is history, cranes and boilers are being dismantled. Instead, new boilers in the halls are now running on natural gas, which can be converted to hydrogen in the future. Above all, the heat will come from another source in the future: the Spree. Since 2023, BTB has been the only heat generator in Berlin to use two river heat pumps. Steel monsters, the size of garages, surrounded by what appears to be a maze of black pipes. On average, they can each provide heat to 2,000 households. Completely without fossil fuels.