Effekter av sänkta framledningstemperaturer på systemeffektivitet, kostnader och kundvärde : En fallstudie av Mälarenergis fjärrvärmenät

Sammanfattning

The purpose of this thesis is to investigate the consequences of reducing the supply temperature in an existing district heating network. The study is carried out as a case study of Mälarenergi's district heating system and focuses on how a stepwise reduction in the supply temperature affects the network's technical operation, economic performance and CO2emissions. The method is based on a comprehensive literature study, data collection, simulations, climate analysis and a techno-economic analysis. The goal is to create a decisionmaking basis where technical conditions, economic aspects and climate benefits can be weighed against each other in a reasonable way. The results show that a reduction of up to 6.50 °C produces predominantly positive effects from all perspectives for the load levels of 300 and 400 MW, with the exception of CO2 emissions which, when reduced by 2.5 °C in the 400 MW case, increase slightly. For a load level of 300 MW, a reduction of up to 4.50 °C is considered feasible and for the 150 MW case, a reduction of 2.50 °C. However, the positive effects at the lower load levels are not as prominent as for the higher load levels. The conclusion is that there are major advantages to reducing the supply temperature in Mälarenergi's district heating network. In the case of 400 MW and 300 MW the recommended temperature decrease is 6,50 °C. In the 225 MW operating level, a reduction of the supply temperature has a small negative economic consequence, but it shows positive effects in terms of CO2 emissions. In this case, it is a question of priority what Mälarenergi thinks is most beneficial between a marginal increase in costs or a reduction in CO2 emissions. In the 150 MW case, the result shows that a reduction of 2.50 ºC has the greatest positive effects.