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Heat from waste water for the district heating network

The city of Heidelberg has tightened its climate targets and wants to become climate-neutral by 2030. To achieve this, the city administration is implementing many measures, such as the expansion of green district heating. At the same time, the municipal utilities commissioned feasibility studies for many energy areas such as biomass and geothermal probes or grid hydraulics. The results of these studies are being incorporated into a transformation plan. goodmen energy prepared a feasibility study on the district heating potential of wastewater from the sewage treatment plant in conjunction with a high-capacity heat pump. This is a prerequisite for funding the subsequent measures in accordance with BEW (federal subsidy for efficient heating networks).

Our services:

Feasability study

Potential analysis

River and waste water

Economic efficiency calculation


The task for goodmen energy was to analyse the technical feasibility of a wastewater heat pump and calculate its efficiency. This also involved taking into account the electricity required to operate the heat pump and determining the performance of the system. The investment costs and - for a model case - possible operating costs were also determined. 
Due to the location on the Neckar, goodmen energy suggested the additional investigation of the possibility of a river water heat pump. Comparisons of heat generation from wastewater and/or river water were drawn up for different scenarios, which ultimately led us to recommend the combined utilisation of the two sources.
Only slightly higher investment costs speak in favour of this - an additional river water heat pump at the location of the sewage treatment plant could also use the electrical and thermal connection of the wastewater heat pump. At the same time, there would be a backup solution with the river as a larger source and the wastewater as a more thermally effective source, especially in winter, which would also compensate for downtimes of the river water (if it is too cold for extraction on a few days of the year). The result is a greater extraction capacity. 
In the feasibility study, the engineers also focussed on the search for a location for the heat pump system and examined its technical suitability as well as its investment and operating costs (especially additional pump power requirements).