Analysis of Different Climate-Neutral Heat Supply Concepts for a District Heating System near Munich with Deep Geothermal Heat as the Primary Heat Source

Abstract

District heating systems are one key element of the transition towards a climate-neutral heat supply since they allow for the use of various renewable energy sources and the increase of renewable heat generation, in particular when combined with seasonal thermal energy storage. Deep geothermal heat is a renewable heat source that can be used to cover the thermal base load of such a district heating system. Also in combination with other renewable heat sources, such as solar thermal or heat pumps, a climate-neutral heat supply for districts or even complete cities can be realised. This paper deals with the analysis of different climate-neutral heat supply concepts that were elaborated for a district heating system currently in the planning phase using deep geothermal heat as the primary heat source, located in the town of Graefelfing near Munich, Germany. The authors present, discuss and assess various options regarding renewable heat sources and including (seasonal) thermal energy storage, to fully cover the thermal loads of a new district heating system in a technically, economically and environmentally favourable way. As a result of this study, a heat supply concept was selected, in which a heat pump using the return flow of the deep geothermal circuit as a heat source maximises the utilisation of the available deep geothermal heat source to cover more than 95 % of the annual heat demand by deep geothermal heat combined with a heat pump.