Thermo-economic optimization of a combined cooling, heating and power system based on small-scale compressed air energy storage

Energy storage systems are important for dealing with the fluctuation of renewable energies in course of their increasing penetration into the energy market. Small-scale compressed air energy storage (CAES) with artificial air vessels can improve the supply capacity of power system and the utilization of renewable energy by storing excess power during off-peak time and releasing it for on-peak power supply and becomes more promising for distributed energy systems. For diabatic CAES, heat usually cannot be efficiently utilized and the low inlet temperature of turbine in an adiabatic-CAES (A-CAES) usually leads to low discharge efficiency. To address these problems, in this paper, we propose a novel combined cooling, heating and power system (CCHP) based on small-scale CAES. The sensitivity analysis performed shows the effectiveness of heat exchanger, and the air temperature and pressure at the turbine inlet have great influence on the system's thermodynamic performance. Then, the trade-off between the thermodynamic and economic performances is investigated by an evolutionary multi-objective algorithm. The total investment cost per output power of the Pareto solutions does not increase significantly when increasing exergy efficiency below 51%, indicating the solutions with an exergy efficiency of around 51% are promising for practical designs.