In large cities such as Cologne, heat generation accounts for more than two-thirds of stationary energy consumption. This is why it is necessary to consider ways to make more efficient use of non-fossil energy sources and create more sustainable heating systems in metropolitan areas. One idea is to recover heat from wastewater systems that is currently simply flushed away.
Waste heat recovery is the transfer and use of residual heat from a thermodynamic cycle, industrial process or a different heat source such as the operation of computers in a data center, which would otherwise be discarded into the environment. This residual heat with high operating temperatures can be used as useful heat at lower temperatures in the same system (preheating) or transferred to an adjacent system for further energy generation such as Rankine cycle for electricity generation and district heating network for space heating.