

Company Vienna Energy of Vienna is preparing to test the largest heat pump in Europe to obtain energy from domestic wastewater.
The plant it consists of 3 heat pumps nine meters long, seven meters high, weighing over 205 tons each, with an energy capacity of 55 megawatts. As soon as it is activated, by 2023, it will be sufficient to meet the energy needs of 56.000 Viennese families.
According to some studies conducted in Germany and Switzerland, 3% of all buildings could be air-conditioned (heated or cooled) by exploiting heat from wastewater. (1)
The exhausts households in the sewage systems, in fact, have a temperature between 10 °C and 25 °C which can be recovered by means of heat pumps.
In the plant di Vienna Energy already cleaned wastewater arrives, normally destined to flow into the Danube. Inside, heat exchangers extract around 6 degrees from the water Celsius (or centigrade).
Thanks for the job of modern technologies, this temperature is used to generate heat at over 90 degrees, which will flow in the form of hot water into the district heating network.
In this way, two-thirds of the energy will be generated from heat extracted from wastewater and one-third from the nearby power plant Verbund Danube in Freudenau, which also uses renewable energy sources.

Presse-Service Rathauskorrespondenz Stadt Wien
Vienna Energy plans to expand the plant by 2027 with another 3 heat pumps and reach 5.000 liters of water per second, which will flow through the 6 pumps.
According to the European Environment Agency (EEA) Wastewater treatment will play a key role in moving Europe towards a zero-pollution future by minimizing dependence on fossil fuels and improving plant efficiency while minimizing the price of heating for users. (2)
Furthermore, it will have a positive impact in terms of the circular economy.
According to the Report 'Beyond water quality – Sewage treatment in a circular economy', published on 5 July 2022 by the EEA, with the use of innovative technologies such plants could also act as 'resource centres' supplying water, energy, nutrients and recovered organic materials for re-use and recycling.
These plants will therefore be able to make substantial contributions to the European Green Deal not only for the Zero Pollution Action Plan, (3) but also for the Circular Economy Action Plan. (4)
Elena Bosani
Note
(2) https://www.eea.europa.eu/publications/beyond-water-quality-sewage-treatment;
(3) https://eur-lex.europa.eu/legal-content/IT/TXT/HTML/?uri=CELEX:52021DC0400&from=EN;
(4) https://eur-lex.europa.eu/legal-content/IT/TXT/?qid=1583933814386&uri=COM%3A2020%3A98%3AFIN

Attorney at law in Milan and Frankfurt am Main. An expert in family, juvenile and criminal law, she is now enrolled in a university master's degree in food law