Key design issues of lined tunnels and shafts used for compressed air energy storage

Abstract: Energy storage is of growing importance due the increasing exploitation of renewable energy sources of an intermittent nature. Compressed air energy storage (CAES) plants represent an alternative to pumped-storage reservoirs for storing large quantities of energy. The peculiarity of CAES is that gas must be stored under a high pressure (up to 30 MPa) in order to achieve the necessary efficiencies. A lined rock cavern (LRC) in the form of a tunnel or shaft can be used within this pressure range. The internal gas pressure is borne by the rock, while the tightness and stability of the system is guaranteed by a mixed composite lining consisting of a thin steel inner shell and a reinforced concrete outer shell.