Thermodynamic assessment of a novel compressed air energy storage system coupled with thermochemical conversion and organic Rankine cycle

The increasing penetration rate of renewable energy sources in energy systems is facing great challenges due to the inherent nature of randomness and the intermittent of renewable energy sources. Compressed air energy storage could smoothen the fluctuations of renewable electricity. Using compression heat as the driving source of the endothermic thermochemical reaction is an advanced way to achieve high efficiency because of the high energy level of fuels and the cancelation of the heat loss and dissipation resulting from the heat transfer process. In this study, a novel energy system that integrates compressed air energy storage, thermochemical conversion, and organic Rankine cycle was proposed and investigated. The sensitivity analysis is employed to assess the impact of three key operating parameters on the performance characteristics of the proposed system. In order to further improve the thermodynamic performance, the comparison of working fluids for organic Rankine cycle is carried out. The results show that higher values of pressure ratio of air compressor and gas turbine and lower values of air–methanol ratio are helpful for the system to operate efficiently. Through the comparison analysis, the organic Rankine cycle with R32 as the working fluid is the best alternative, the system incorporating an R32-based organic Rankine cycle demonstrates superior performance, achieving the highest electricity generation of 1295.91 kWh and an exergy efficiency of 64.16% under the design conditions.