Compressed Air Energy Storage in Underground Formations

Unlike fossil energy carriers, renewables are characterized by short-term and long-term fluctuations and therefore cannot supply energy upon demand. The increased use of fluctuating renewable energy sources strengthens the significance of the storage of electrical energy at the grid scale. In addition to pumped hydro technology which has been used successfully for many decades, and future hydrogen systems, there is increasing interest in a storage technology that was developed well over 50 years ago: compressed air energy storage. This process uses electrical energy to compress air and store it under high pressure in underground geological storage facilities. This compressed air can be released on demand to produce electrical energy via a turbine and generator. This chapter describes various plant concepts for the large-scale storage of compressed air and presents the options for underground storage and their suitability in accordance with current engineering practice. Compressed air energy storage projects which are currently in operation, construction, or planning are also presented.