Heat recovery from sewage water using heat pumps in cologne: A case study

Heating and cooling are responsible for half of the EU's energy consumption. A lot of heat is being wasted in the industries. In fact, it is calculated that if waste heat was recovered, the entire EU's building stock heat demand could be covered [1]. Celsius is a co-funded EU research project which is focused on the recovery and the integration of waste energy from local sources in urban heating and cooling systems. The objective of this paper is to show the performance of two of the Celsius demonstrator sites in Cologne. The Celsius demonstrator sites in Cologne supply the heating and domestic hot water (DHW) of public schools. Compression heat pumps recover low grade heat from the sewage network and deliver the annual base heat load of the schools. Gas fired boilers supply the thermal peak loads and act as backup systems. Key performance indicators (KPI) were designed and calculated based on the monitored parameters of each plant. The results of the monitoring assessment show that fuel consumptions and GHG emissions of both demonstrator sites have decreased compared with the baseline situation corresponding to the plant configuration before installing the Celsius demonstrator. However, the costs of reducing both energy consumption and emissions are strongly linked to the performance of the plant.