Heat Pumps and Renewables in District Heating – Evaluation of Central and Decentral Approaches

Abstract

The decarbonization of the building stock and thus of district heating (DH) systems is one of the main future challenges in the building sector. It is controversial which role district heating will play in the future, i.e. to what extent an expansion of DH is beneficial and necessary, but it is undisputed that DH will take or hold a relevant share. With the increasing decarbonisation of the electricity mix, the use of heat pumps (HP) in buildings will be significantly more competitive than (existing fossil-based) DH systems, at least in terms of CO2 emissions. On the other hand, especially in urban areas and in existing buildings, the use of heat pumps is limited and also technically and economically challenging (source exploitation, space restrictions, architecture, sound emissions, etc.). Decarbonisation of DH might include waste heat, geothermal or solar thermal and heat pumps (in combination with electricity from renewables). Both, decarbonization of DH and electricity mix is challenging and full decarbonization requires electrical and thermal energy storage. Based on the energetic and ecological evaluation of exemplarily DH systems, different variants considering heat pumps integration, i.e. large central HPs central DH or block-wise or decentral i.e. building-wise, or apartment-wise are compared and evaluated. The assessment includes the own-consumption of the Photovoltaic (PV) yield and is then expanded to include various scenarios for the development of the electricity mix and the decarbonisation of DH.