Search for potential Compressed Air Energy Storage sites in Switzerland

Abstract

The energy transition process in Switzerland foresees a move away from nuclear energy. This calls for an expansion of alternative energy sources such as solar or wind. Since these types of energy generation depend on the weather, the energy generated must be stored to be available on demand. In addition to pumped storage plants, compressed air energy storage (CAES) in underground cavities offers a potential solution for this problem. The economic viability of a CAES system depends on the investment costs as well as the overall efficiency of the system, i.e., storage and recovery of the energy. The paper describes the search for a suitable site in Switzerland for an envisioned adiabatic, high pressure (100 bar) CAES with the potential to store 500 MWh of energy. First, the minimum dimensions and possible arrangements of all the cavities required by the CAES facility are determined. Subsequently, relevant hazard scenarios are identified and analysed from the geotechnical viewpoint. A determination is then made of the requirements, such as rock strength, overburden or distance to the valley flanks of the high-pressure underground chamber. In addition, potential damage to the chamber’s sealing is analysed and the plug of the high-pressure chamber is dimensioned structurally. Finally, potential sites are selected with the help of a GIS system incorporating the geological and topographical map of Switzerland.