Exergy and exergoeconomic analysis of a Compressed Air Energy Storage combined with a district energy system

•CAES and CAES with thermal storage systems were investigated.•The potential for using heat generated during the compression stage was analysed.•CAES-TS has the potential to be used both as energy storage and heat source.•CAES-TS could be a useful tool for balancing overall energy demand and supply. The potential for using heat generated during the compression stage of a Compressed Air Energy Storage system was investigated using exergy and exergoeconomic analysis. Two Compressed Air Energy Storage systems were analysed: Compressed Air Energy Storage (CAES) and Compressed Air Energy Storage combined with Thermal Storage (CAES-TS) connected to a district heating network. The maximum output of the CAES was 100MWe and the output of the CAES-TS was 100MWe and 105MWth. The study shows that 308GWh/year of electricity and 466GWh/year of fuel are used to generate 375GWh/year of electricity. During the compression of air 289GWh/year of heat is generated, which is wasted in the CAES and used for district heating in the CAES-TS system. Energy efficiency of the CAES system was around 48% and the efficiency of CAES-TS was 86%. Exergoeconomic analysis shows that the exergy cost of electricity generated in the CAES was 13.89¢/kWh, and the exergy cost of electricity generated in the CAES-TS was 11.20¢/kWh. The exergy cost of heat was 22.24¢/kWh in the CAES-TS system. The study shows that CAES-TS has the potential to be used both as energy storage and heat source and could be a useful tool for balancing overall energy demand and supply.