Energy system analysis of CAES technologies in the Danish energy system with high penetration of fluctuating renewable energy sources

Wind power supplies 20% of the annual electricity demand in Denmark, while 50% is produced by combined heat and power (CHP). The installed wind turbine capacity in Western Denmark exceeds the local demand at certain points in time. So far, excess production has been exported to neighbouring countries. However, plans to expand wind power locally and in the neighbouring countries could restrain the export option and create transmission congestion challenges. This results in a need to increase the flexibility of the local electricity system. Compressed Air Energy Storage (CAES) has been proposed as a potential solution for levelling fluctuating wind power production and maintaining system balance. Compared to other electricity storage technologies, CAES provides a large storage capacity using readily available technologies. Results from this paper, however, show that in order to have a significant effect on reducing excess electricity production, the storage capacity of CAES has to be increased significantly compared to current technology. It is thus concluded that, seen from a local energy system balance perspective, CAES has little potential for reducing excess electricity production and facilitating high wind power penetration. The study did not, however, consider other possible benefits of a CAES plant such as e.g. providing regulating power