A pilot scale research was carried out to verify the feasibility of compressed air storage in lined rock cavern. Two caverns with a diameter of 6m were excavated at a depth of 100 m below the surface ground in a mine. This paper presents assessment technologies of geomechanical characteristics and performance of a compressed air energy storage system in lined rock cavern. The thermo-hydro-mechanical analysis using the coupled TOUGH-FLAC has been conducted to simulate the performance of the CAES pilot, to assess geomechanical stability, and to predict air leakage of lined rock cavern system under the long-term operation condition. Multi-channel borehole tests has been done to measure air and water permeability of the system, and also a borehole seismic exploration has been performed to characterize the excavation damaged zone surrounding the storage caverns.
Compressed air energy storage (CAES) in rock is considered as one of the effective technologies for large amount of electric energy storage. In the case of CAES in underground, lining of rock caverns is essential to prevent air leakage Construction of lined rock cavern (LRC) is more expensive than salt domes. However, CAES system in LRC has some advantages in the respect of the site selection and the liaison between production and demand. Moreover, they can reduce an additional expense due to construction of storage space at depth since lined system allows air tightness and mechanical stability (Song et al. 2012). Air tightness and mechanical stability are the key factors in underground storage of compressed air. These depend on the various design factors such as the shape and volume of storage caverns, the depth, operation pressure, water table, rock strength and permeability.
A pilot scale study on underground CAES has been carried out. The purpose of this project is to develop core technologies for CAES in lined rock cavern. A pilot plant is designed for 1 MW-scale LRC system and constructed at about 100m depth of an on-going mine. The R&D program of the project includes the key topics such as investigation of feasibility of the concept, specification of optimum lining components for a given pilot scale, development of field-scale test apparatuses of permeability and excavation damaged zone (EDZ) of lining and rock mass, assessment of air tightness of LRC system, analysis of long-term stability, assessment of geomechanical and thermodynamic performance of CAES in LRC.
