Multi-objective optimization of a gas turbine-based CCHP combined with solar and compressed air energy storage system

Abstract

The small-scale compressed air energy storage system (CAES) combined with renewable energy sources (RES) is becoming increasing popular in distributed energy system (DES), which allows RES uninterrupted and improves the supply capacity of power system. In order to balance the electricity load and improve the energy efficiency of CCHP system in combined cooling, heating and power (CCHP) system, the paper described a CCHP system combined with solar and compressed air energy storage (CCHP-S-CAES). Solar energy was coupled with the CAES in this paper to heat the high-pressure air from air storage cavern. The proposed system consists of a conventional CCHP, a CAES and a solar energy collector/storage system, which stores the surplus electric power of gas turbine during off-peak time and releases it during on-peak time. Sensitivity analysis on the CCHP-S-CAES system was conducted to investigate the effects of the key parameters on its performances. It is clear that the performances of the CCHP-S-CAES system are mainly determined by the pressure ratio of compressor, the inlet pressure and temperature of turbine and the effectiveness of heat exchangers. In addition, a multi-objective optimization based on the Non-dominated sorting Genetic Algorithm-II (NSGA-II) is performed for obtaining the optimum performance of the CCHP-S-CAES system from the view of investment cost and exergy efficiency. The results show that the optimal exergy efficiency of the proposed system is about 53.10% and 45.36% in maximum heating condition and maximum cooling condition respectively.