Compressed Air Energy Storage in the German Energy System – Status Quo & Perspectives

The ongoing transformation of the German energy system calls for both new technologies and new methods to assess the role these technologies can play in future energy scenarios. This paper presents a new methodology that combines detailed thermodynamic process modelling and investor-centered economical evaluation to form an integrated technology assessment of compressed air energy storage plants. The respective model derives characteristics for charging and discharging operation of these plants from detailed component level process calculations. These characteristics are then processed in a unit commitment model that optimises plant operation in terms of market revenues using mixed integer linear programming. Arbitrary energy systems are represented by time series of spot and tertiary control reserve markets. In a case study, three different plant layouts are investigated using historical data and future price variations on the German energy market. It shows that simple conventional plant layouts would presently generate the highest profitability. Adiabatic storage systems tend to be an even better option if the price spread should increase in future markets. However, the profitability strongly relies on revenues from the control reserve market. The high volatility of this market explains why potential investors currently show restraint with respect to compressed air energy storage plants.