DETERMINATION OF SAFE WITHDRAWAL RATES OF COMPRESSED-AIR ENERGY STORAGE IN SALT CAVERNS

Abstract

The objective of this study is to determine effects of loading rate on compressive strength and deformability of the Maha Sarakham salt under elevated temperatures. The effort is aimed at determining the safe maximum withdrawal rates for the compressed-air energy storage (CAES) in salt caverns. The constant axial stress rates range from 0.0001 to 0.1 MPa/s. The testing temperatures are maintained constant between 273 and 373 Kelvin. To incorporate the thermal and rate (time-dependent) effects into a strength criterion the distortional strain energy at dilation of the salt is calculated as a function of the mean strain energy density. Finite difference analyses (FLAC 4.0) are performed to determine the stresses and strains at the boundaries of CAES caverns for various reduction rates of the internal pressures. The maximum stresses and strains obtained during retrieval period are used to calculate the strain energy density induced at the cavern boundaries. The results are compared against the criterion developed above, and hence the safe maximum withdrawal rate of the compressed-air can be determined.