A lignite mine is located in the proximity of the town, where the sump water is extracted from the mine to prevent the ground water to seep into the pit.
This water was used by the cooling towers of a nearby power plant, and the rest was dumped into a nearby river. As this water has a temperature of 26°C, it is now collected by two heat pumps to cool it down to 10°C, and the heat is used to supply a local district heating system. The two heat pumps use the R134a refrigerant, which is a hydrofluorocarbon with low GWP, and provide supply temperatures of approximately 55 – 60°C, whilst achieving a COP of 4,4. The first unit was commissioned in March 2014, and given it’s success, the second unit was installed at the beginning of 2015. Now, the system is providing heat to the offices of Erftverband, which house approximately 500 employees. Based on an energy demand of 1200 MWh, the local non-pro t water supply and distribution association saves 58 000 Euro/year.