Evaluation of the energy potential of an adiabatic compressed air energy storage system based on a novel thermal energy storage system in a post mining shaft

Abstract

The paper describes an energy storage system that uses compressed air and thermal energy storage, enabling installation in a post-exploitation mine shaft. The paper presents the concept and construction of thermal energy and compressed air hybrid storage system. Storage potential and effectiveness of the compressed air energy storage (CAES) system are demonstrated. The main motivation for undertaking the research was to manage post-mining infrastructure, especially in highly urbanized areas, and to propose a system to compensate for power fluctuations in the power system. The analyzed system includes a two-section air compressor, one compressed air reservoir with built-in two-section thermal energy system and a two-section air expander. The proposed energy storage system uses a post-mine shaft with a volume of about 60,000 m3 and the proposed thermal energy and compressed air storage system can be characterized by energy capacities of 140 MWh at a moderate pressure of 5 MPa. Important features of the system that determine high values of electric energy storage efficiency, in excess of 70 %, are identified. A numerical investigation of the Thermal Energy Storage (TES) tank supported by experimental studies is also presented, and the energy efficiency of the TES was calculated to be 95 %. This paper provides a detailed description of the concept, discusses its advantages and limitations, and highlights areas for future research.