Economical and technical evaluation of energy storage systems

In the context of the increasing integration of non-dispatchable renewable energies, electricity storage is discussed as a possible solution to better match supply and demand. This paper evaluates innovative storage technologies for the stationary storage of electricity from intermittent renewable energy sources. The technologies analyzed using a multi-criteria methodology include Redox-Flow-Batteries (RFBs), thermal and compressed air storage (TACAS) and hydrogen storage via electrolysis (H2). An expert survey was conducted to assess the relative importance of criteria and derive weightings for the multi-criteria assessment based on the Analytic Hierarchy Process (AHP). The results of the multi-criteria analysis are presented. In the longer term, only those technologies will be applied that are economically feasible. Therefore, in addition, a detailed profitability analysis was carried out. As innovative electricity storage technologies need to compete with conventional electricity storage technologies and other flexibility options for energy supply, their economic profitability was also compared with conventional batteries, in particular with lead-acid and sodium-sulfur batteries. The results show that costs need to be substantially reduced for electricity storage technologies to be economically feasible in stationary storage applications. Thus, further research and development is needed to exploit the technical potentials for stationary electricity storage in the future.