Evaluation of electricity storage versus thermal storage as part of two different energy planning approaches for the islands Samsø and Orkney

Highlights: • Local resources and energy production should be better integrated locally. • Storages can help increase self-sufficiency and independence of islands with RES. • BESS reduce import and export of electricity and can reduce fuel consumption. • TES integrate excess electricity via heat pumps in a fuel-reducing and economic way. • Heat pumps are important for integrating the electricity in the heating sector. -- Abstract: Island energy systems should aim for a better integration of local resources and exploit their potential for local energy supply to increase their independence and security of supply besides other benefits. Two trends addressing this problem can be observed: On the one hand, increasing the local use of renewable electricity in the electricity sector by investing in Battery Energy Storage Systems (BESS). On the other hand, the integration of all energy sectors into a Smart Energy System (SES) with the conversion of renewable electricity to heat – thus enabling the usage of Thermal Energy Storage (TES). In this paper, these two potential approaches are investigated through energy systems analyses using EnergyPLAN for the Danish island Samsø and the Orkney islands in Scotland. This investigation shows that BESS tend to address only the electricity sector, while TES furthermore improves issues in the heating sector and enables possibilities in the transport sector. The TES approach results in overall reduced energy system costs, while the BESS has a stronger effect on the exchange of electricity. Depending on the various energy systems, both approaches present potential solutions, while the SES approach with the use of TES demonstrates more advantages for the whole energy system.