Techno-economic feasibility of prosumers in urban district heating systems utilising low-temperature industrial excess heat

Industrial sites have considerable potential to utilise low-temperature excess heat from cooling for heating via heat pumps, limited mainly by the overlap of heating and cooling demand profiles. Coupling industrial heating and cooling infrastructure with district heating (DH) systems is therefore an attractive solution, as DH requires new heat sources for decarbonisation. This article examines the techno-economic feasibility of converting a DH substation at a German production site into a prosumer using a TRNSYS simulation model incorporating a heat pump, cold and heat storage, and allowing for bi-directional heat transfer at the DH substation. Subsequent optimisation minimised the levelised cost of heating and cooling (LCOHC) at the industrial site by adjusting the heat pump capacity. The results indicate that the integration of the heat pump, without heat feed-in, reduces the LCOHC by about 10% compared to decoupled heating and cooling. However, to achieve similar LCOHC in a prosumer configuration, which includes feeding surplus heat into the DH network, a compensation payment of 80% of current DH costs is required. This arrangement allows a 10% increase in heat pump capacity and a 27% increase in heat pump output, providing 4 GWh/a of surplus heat to the DH system from May to September.