Thermal-economic performance analysis of AA-CAES system with multi-objective optimization

In the development and engineering application of advanced adiabatic compressed air energy storage (AA-CAES), system performance optimization is essential to get the best energy storage efficiency with the lowest cost. However, in general, thermal and economic performances cannot be simultaneously optimal. To solve this problem, a multi-objective optimization is adopted in this work. Energy and economic models of the AA-CAES system are established to obtain the system performances. On this basis, system performances under basic conditions and the effects of operation parameters are obtained. With the maximum round-trip efficiency (RTE) and the minimum total capital cost (TCC) as the optimization objectives, key system parameters, including pinch point temperature difference (PPTD), compressor outlet temperature and sliding pressure range, are optimized with the Non-Dominated Sorting Genetic Algorithm (NSGA-II). The results indicate that under basic conditions, RTE of the system is 67.64 % and TCC is $13.127 × 107. With the increase of PPTD, RTE decreases, while TCC first decreases and then increases. As the compressor outlet temperature increases, TCC gradually decreases, while RTE increases first and then decreases. Furthermore, every 1 MPa increase of sliding pressure range increases RTE by 0.16 %, and decreases TCC by $1.300 × 107. After multi-objective optimization, the optimal RTE is 67.96 %, and TCC is $11.672 × 107. Compared with the performances under basic conditions, RTE increases by 0.32 % and TCC decreases by $1.455 × 107.