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Wind and solar power have embraced a strong development in recent years due to the energy crisis in China. However, owing to their nature of fluctuation and intermittency, some power grid management problems can be caused. Therefore a novel hybrid wind-solar-compressed air energy storage (WS-CAES) system was proposed to solve the problems. The WS-CAES system can store unstable wind and solar power for a stable output of electric energy and hot water. Also, combined with organic Rankin cycle (ORC), the cascade utilization of energy with different qualities was achieved in the WS-CAES system. Aiming to obtain the optimum performance, the analysis of energy, exergy and parametric sensitivity were all conducted for this system. Furthermore, exergy destruction ratio of each component in the WS-CAES system was presented. The results show that the electric energy storage efficiency, round trip efficiency and exergy efficiency can reach 87.7%, 61.2% and 65.4%, respectively. Meanwhile, the parameters analysis demonstrates that the increase of ambient temperature has a negative effect on the system performance, while the increase of turbine inlet temperature has a positive effect. However, when the air turbine inlet pressure varies, there is a tradeoff between the system performance and the energy storage density. [ABSTRACT FROM AUTHOR]

• A variable trigeneration system based on liquid air energy storage is proposed. • Systematic thermo-economic analysis for different seasons and regions is made. • Better performance comes from higher ambient temperature and energy price. Liquid air energy storage is a promising long-time energy storage technology with the advantages of large capacity and no geographical restrictions. However, the cycle efficiency still has potential to improve and the operation modes need to be investigated. Thus a novel trigeneration system based on the liquid air energy storage is proposed. The system can store the off-peak electricity and supply the cooling, heating and power at the peak time. With different needs for the multiple energy, the optimal configuration of the trigeneration system for different seasons is studied, and the thermodynamics and economics are both analyzed. The results show that the round-trip efficiencies of the system in winter, the transition season and summer for Jinan City are 55.41%, 55.35% and 54.68%, respectively. The dynamic payback period and the levelized cost of energy for the trigeneration system are 5.46 years and 0.13 $/kWh, respectively. Furthermore, the thermo-economic analysis of five typical regions in China is carried out. Guangzhou City owns the best economic performance with the largest annual total profit of 709.81 k$ and the smallest dynamic payback period of 4.49 years. It can be concluded that the system has inspiring adaptability and feasibility under variable operation modes. [ABSTRACT FROM AUTHOR]