Techno-economic analysis of heat recovery from supermarket’s CO2 refrigeration systems to district heating networks

This paper investigates the opportunity of utilizing the spare heating capacity of CO2 refrigeration systems in supermarkets to produce heat to be sold to district heating network operators. A comprehensive description and assessment of two control strategies that could be implemented to enable the heat export function are presented. To maximise the heating capacity during the coldest moments of the year, the integration of geothermal storage with the CO2 system was investigated as an additional scenario. The BIN method was used to perform annual energy calculations. Furthermore, a sensitivity analysis was carried out on the most critical parameters, namely the heating demand, price ratio and temperature levels of the district heating network. For the assumed prices and energy demands, the supermarket could make profits corresponding to up to 16% (10,000 €/year) of the annual energy cost by selling part of the heat recovered to the district heating network operator. Furthermore, the heat exported could save up to 18% of the annual CO2 emissions of the supermarket compared to the baseline. Finally, the sensitivity analysis showed that the economics of this solution is the more profitable, the lower return temperature of the heating network where the installation is connected.