Electricity Storage Systems and Their Allocation in the German Power System

The need for daily electricity storage systems increases with the growing share of volatile renewable energy in the generation mix. Since the location of decentralized electricity generation (based on reneweable energy resource potentials) and electricity demand (depending on industrial facilities and population density) in Germany are geographically apart from each other, at the same time more electricity has to be transported. At certain times, this might challenge the transmission grid. Storage systems can be used for storing the surplus production of renewable energy and also help to prevent congestions in the grid. However, besides the technical feasibility there are economic criteria decisive for the installation of storage systems. These depend firstly on potential alternative technologies as gas turbines or the load shift potential of electric vehicles and secondly on the price development of storage systems. In order to estimate the future demand and the strategic allocation of daily storage systems in this context, expansion options for storage systems are implemented in the optimizing energy system model PERSEUS-NET-TS. This is a myopic material and energy flow model with an integrated nodal pricing approach. A mixed-integer optimization calculates the expansion and use of power plants in Germany until 2040 considering the DC restrictions of the transmission grid. Hence, the commissioning and allocation of storage systems in the German transmission grid is determined when the government target of 60 % renewable feed-in by 2040 is met. For this paper about every forth car in Germany is considered to drive electrically by 2040. When they are charged uncontrolled, directly after arrival the results are that by 2040 about 19 GW of storage systems are commissioned. Most are built closely to generation centers, but some are allocated close to bottlenecks in the transmission grid instead. When load shifting of the demand for electric mobility is allowed in terms of a controlled charging the required daily storage capacity could be reduced by more than half, so that only 8 GW are needed in 2040.