Wastewaster Recycling : Vienna: heat recycling system at local spa

Wien Energie has built a heat pump system at Therme Wien and uses the waste heat from the thermal wastewater to generate district heating. The waste water, which has a temperature of around 30 degrees, is used to generate district heating for around 1,900 households in the immediate vicinity.

"Heat from the neighbourhood for the neighbourhood: It is precisely because of solutions like this that Vienna is a climate model city! Wien Energie uses valuable waste heat from the thermal water of the Vienna Thermal Baths to generate district heating. The project is another building block for climate protection and an important step towards greater independence from gas imports," says Peter Hanke, City Councillor for Economic Affairs.

Wien Energie has invested around 3 million euros in the project, which will further increase the share of climate-friendly heat production. By 2027, the company will have invested one billion euros in phasing out gas. The thermal spring, which has been used by Therme Wien since the mid-1950s, takes on yet another function with this project.

Wien Energie has installed two heat pumps in an extended technical room in the underground car park of the Therme Wien. These heat pumps have a direct connection to the collected thermal wastewater. The principle of heat generation works like a refrigerator - only in reverse. The heat pumps absorb the residual heat from the thermal wastewater at a temperature of around 30 degrees Celsius and use it to produce district heating at up to 85 degrees Celsius. The heat generated is fed directly into the local district heating network in Oberlaa.