Performance evaluation of a combined heat and compressed air energy storage system integrated with ORC for scaling up storage capacity purpose

Integrating compressed air energy storage (CAES) between renewable energy (RE) plants and power grid contributes to mitigate the mismatch between energy supply and consumption. However, conventional CAES is greatly restricted by the size of cavern and the system power/energy ratings for a specific geological condition are difficult to boost up. In this paper, a combined heat and compressed air energy storage (CH-CAES) system integrated with organic Rankine cycle (ORC) is proposed. The system introduces an independent electrical heating unit paralleling to the adiabatic CAES (A-CAES) so as to enlarge system capacity. The thermodynamic analysis under basic load shows that the charge capacity increases by about 21.3% than conventional A-CAES, and the energy generated per unit volume of storage (EVR) is 3.23 kWh/m(3), 10.2% larger than that of conventional A-CAES. Additionally, the proposed system has been proved to have great flexibility to meet different user demands. Off-design performance analysis for compressors, turbines, ORC turbine and pump are carried out and link between these components are revealed. Effect of partial charging/discharging on system overall performance has been also discussed. In brief, the proposed system is flexible and energy dense. It could give a potential to improve system capacity in a limited geographical location. (C) 2019 Elsevier Ltd. All rights reserved.