ABSTRACT
The concern about climate change and global warming has triggered global paradigm shift and different energy industrial environment. Energy storage system (ESS) comes into the spotlight as an emerging industry. Especially, compressed air energy storage (CAES), which has a long history of commercialization, gets reappraisal as a competitive ESS technology at a utility scale. However, it has been mentioned that CAES has a weakness of site limitation. Rock engineering is expected to make its key roles for CAES to overcome the limitation and penetration into ESS market successfully. We here consider the CAES types with underground storage cavern in a rock salt and hard rock, and key issues of rock engineering in implementing these types of CAES are presented. In a rock salt, the shape and pillar width of multiple storage caverns are important for bulk storage implementation. In a hard rock, a field experiment of air tightness, structural stability, energy balance and efficiency analysis during operation in the storage system should be interesting topics. We introduce a sophisticated apparatus and evaluation procedure for the characterization of air tightness in the components of storage system. We also demonstrate the results of reliability-based analysis and sensitivity analysis of the parameters for the stability of the structure at a shallow depth. And the results of energy balance and efficiency analysis through the coupling analysis are presented under the various operation modes of the system.
