German utilities harvest wastewater to heat and cool Berlin building


German utility companies E.ON and Berliner Wasserbetriebe have partnered with real estate company SIGNA to ensure low-carbon heating and cooling of buildings.

With the heating of buildings and cities accounting for an increasing chunk of the carbon emitted into the air, meeting the growing energy demand of the sector using renewable or low-carbon resources is vital.

This is the main aim of a partnership established by the three parties in which they are using heat and cold harvested from within the wastewater network to either cool or heat buildings.

The three have transformed Berlin railway station Berlin Ostbahnhof into an office building and are harvesting cold and heat from a 100-year old gravity sewer.

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A stainless-steel heat exchanger has been installed next to the building to extract existing heat from wastewater, after which a large heat pump increases the temperature of the heat generated and heats the building. In the summer, the principle is reversed, and the channel is used as an efficient source of cooling. In addition, a combined heat and power plant is used for a highly efficient and affordable supply of electricity, coupled with a cooling system and a gas condensing boiler.

The project withdraws power of more than 600KW. Nikolaus Meyer, Head of Solution Development at E.ON, said: “This way, we cover around 50 percent of the heating and cooling needs of the building in a sustainable way and save around 400 tons of CO2.”

In addition to ensuring the decarbonisation of the heating and cooling sectors, leveraging wastewater provides a cost-effective and space-saving way to mitigate climate change.

The launch of the project comes at a time when a large part of the energy in Germany, almost 1,220TWh, is used in the heating sector yet only 15% of the energy is sourced from clean alternatives. In Germany alone, energy generated from wastewater could cover 14% of the heat demand in the building sector and be used equally for cooling.

Reiner Müller, Head of Project Development at SIGNA Real Estate, adds: “By retaining the existing structure and using state-of-the-art heating and cooling technology, we achieve an excellent CO2 balance at the UP!”