Abstract
This paper describes the results of the measurements of energy budget during a pilot test of storing energy by compressing air into an unlined natural rock cavern and proposes a thermos-fluid model for evaluating the energy storage efficiency. It also shows that relatively simple measurements enable evaluation of the energy stored, leaked and transmitted into surrounding rock and that the energy loss to the rock can be significant. The entire storage process can be described by a relatively simple control-volume analysis based on the conservation laws. The method can be applied to evaluate efficiency of storing other fluids in underground cavern.
