Economic feasibility of booster heat pumps in heat pump-based district heating systems

District heating systems are appropriate infrastructures to supply space heating and domestic hot water from a number of potential sources in future energy systems based on renewable energy. On the other hand, district heating is also facing competition from heating technologies in individual buildings. Lowering the district heating temperatures will improve efficiency and competitiveness of district heating; however, the production of domestic hot water is an impediment to this. This article uses energyPRO to analyse three low-temperature district heating schemes. District heating is supplied from a heat pump using air, seawater or groundwater as heat sources. Domestic hot water is supplied by booster heat pumps using district heating as heat source or through a heat exchanger. The economic benefit of adding booster heat pumps to cover the domestic hot water demands is assessed by modelling the time-varying operation against the electricity market as well as the time-varying coefficient of performance of heat pumps and grid losses. Based on this operation cost reduction assessment, the energy system value of booster heat pumps ranges from 2500 to 6800€ per house depending on the choice of low-temperature heat source for the district heating heat pump as well as economic time-horizon and discount rate.