Increasing the utilization of local energy potentials through low temperature district heating networks

The development of district heating networks over the last two centuries, changing from steam to pressurized water as medium for heat transport, has been an evolutionary process with various aims: preventing boiler explosions, raising comfort and saving fuels. With the substitution of steam, the supply temperature levels also decreased to 100°C or less, which led to fewer heat and process losses (Lund et al., 2014). However, the advantages of further lowering the supply temperatures to a level of 5°C to 40°C, especially in combination with solar thermal collectors, are unknown. In this paper, we present a modelling approach and a comparison of the thermal losses of a low temperature district heating network and a state-of-the-art district heating network. The thermal losses of the low temperature district heating network amount to 1.89% of the district's total annual heat demand versus 12.97% of thermal losses in a traditional district heating network. The results demonstrate how a further reduction of supply temperatures in district heating networks can reduce the thermal losses significantly and help district heating systems to become more energy efficient.