CASCADE: A comprehensive toolbox for integrating low-temperature sub-networks in existing district heating networks
Low temperature district heating networks (LTDHN) operating at supply temperatures of 50-70°C can very effectively utilize renewable heat sources such as solar or geothermal energy, ambient heat or low temperature waste heat, as described in Lund et al. .
However, the vast majority of urban district heating networks (DHN) operate on relatively high temperatures, typically 90-110°C supply and 50-70°C return. The high-temperature mode of operation has a certain robustness and hightemperature DHNs cannot be easily transformed into a LTDHN, for example due to the characteristics of the building stock, the requirement of transporting sufficient amounts of energy with the given capacities and high temperature heat e.g. from waste incineration.
CASCADE investigates an alternative approach: the integration of LTDHNs into the return line of an existing large urban DHN, thus creating a sub-LTDHN. This will reduce the return temperature of the overall DHN (see figure 1) and thus improve its efficiency and sustainability as well as enable increasing its capacity for connecting new customers. Consequently, sub-LTDHN can be a key enabler for the decarbonization of urban DHN by enabling an efficient utilization of local energy sources and have the potential to reduce substantially the overall network temperatures.
Download the report here:IEA-DHC_XIII-7_CASCADE_Summary_final.pdf