On the role of storage for electricity in smart energy systems

In recent years the electricity system has started to undergo significant changes. Three major developments are underpinning these changes: (i) the rapid digitalization of the energy system leading to smart grids and increasing flexibility in the system; (ii) the increasing electricity generation from variable renewable energy sources, such as wind and solar; and (iii) the continuing decentralization of electricity generation leading to more and more prosumagers (consumers, which also produce energy and store it) instead of former consumers. Among other necessary changes these developments have led to calls for additional storage capacities. The core objective of this paper is to investigate the possible role of electricity storage in such smart energy systems. We consider all relevant types of storage: short-term ones such as pumped hydro storage, small and large stationary battery and the battery of electric vehicles as well as long-term storage such as hydrogen and methane from power-to-gas conversion technologies and compressed air energy storage. The major conclusions of this analysis are: In recent years the options for placing storage in smart energy systems as well as types of storage have been increasing significantly. However, low number of full-load hours is still the major problem of all electricity storage options.