Wien Energie has been building the most powerful and environmentally friendly large-scale heat pump system in Europe on the site next to the ebswien sewage treatment plant for one and a half years. This plant utilises waste heat from the sewage treatment plant. Construction of the first expansion stage, for which Wien Energie invested around 70 million euros, was completed last December. The large-scale climate protection project was then put into operation.
Vienna will be climate-neutral by 2040! The heat pump system at the sewage treatment plant is a major milestone on this path. As a city, we are turning the big screws and utilising every renewable heat source available to us. With this new Wien Energie plant alone, we can already supply up to 56,000 Viennese households with green district heating in the first expansion stage. With our heat pumps, we are pioneers throughout Europe”, said Mayor Michael Ludwig in December on the occasion of the plant's completion.
The plant uses treated wastewater from the neighbouring ebswien sewage treatment plant to generate heat. The heat in the wastewater, which previously flowed unused into the Danube Canal, can thus be put to good use.
100 percent regional and renewable energy
With electricity from the nearby Freudenau power plant on the Danube and waste heat from the sewage treatment plant's wastewater, Wien Energie can operate the large heat pump using 100% renewable energy. However, it is not only the waste heat from the wastewater that is used to generate sustainable energy at the sewage treatment plant, but also the wastewater, sewage sludge, hydropower and solar energy.
Normally, the wastewater from the sewage treatment plant flows into the Danube Canal after purification. From now on, the water will take a diversion into the large heat pump system before it reaches the canal: this is where the heat pumps are located, which use heat exchangers to extract around 6 °C from the purified water. Wien Energie can utilise this low temperature with the modern technology in the highly complex system to generate heat at more than 90 °C. This heat then flows out in the form of hot water. This heat then flows in the form of hot water via the district heating network into tens of thousands of Viennese homes that are supplied with district heating.
Wien Energie obtains the green electricity required to operate the plant directly from the nearby VERBUND Danube power plant in Freudenau. To ensure efficient and optimised operation of the heat pump, Wien Energie has built its own direct line between the power plant and the system. A separate junction was built at the power station for this purpose.
New pumping station for district heating network
Wien Energie has also built a new district heating pumping station in order to be able to distribute these large quantities of heat in the district heating network. There is now a second pumping station at the Simmering power plant site, which - like a heart - pumps up to 7,500 m3 of hot water per hour through the district heating network.
This new pumping station can not only distribute the heat from the heat pumps at the sewage treatment plant, but also other capacities. This is necessary as the district heating network in Vienna is constantly growing. Today, Vienna's district heating network is one of the largest in Europe with a length of over 1,300 kilometres. Wien Energie supplies 440,000 Viennese households and 7,800 large customers with district heating. Wien Energie aims to supply around 56% of Viennese households with climate-neutral district heating by 2040.
