Design Criteria for Compressed Air Storage in Hard Rock

Compressed Air Energy Storage (CAES) in underground caverns can be used to generate electrical power during peak demand periods. The excess power generation capacity, which is available when demand is low, is used to store energy in the form of compressed air. This energy is then retrieved during peak demand periods. The structural features and leakage stabilities of the air storage site determines the efficiencies of energy conversions and corresponding economics. The objectives of this paper is to formulate advanced criteria for design of CAES systems in hard rock in Israel, and to examine specific designs performance through predictions available from numerical models. Underground space provides opportunities for safe storage and conservation of energy. This concerns enhanced protection and security as well as lower response to external thermal and mechanical influences (impact and vibrations) that characterize highly controlled environments. Design examples of CAES system are presented and their geomechanical and thermal responses to compression and air release cycles are considered. Comparison is made between different configurations of CAES systems with respect to their expected technical and economical performance. Finally, a new CAES system, that incorporates a vortex tube for enhanced thermal efficiency, is described.