Performance evaluation of a renewable driven standalone combined power and water supply system with cascade electricity and heat storage

The reliable supply of electricity and freshwater is linked to the living quality of local residents in remote islands. A renewable driven standalone combined power and water supply system with cascade electricity and heat storage is proposed in this paper. The hybrid wind-solar power system acts as the energy source and the humidification dehumidification (HDH) desalination is employed for freshwater production. The underwater compressed air energy storage (UW-CAES) is introduced to smooth the renewable fluctuations, whereas the heat storage system for heat addition purpose of HDH desalination is utilized to reduce dumped power during UW-CAES charging. The simulated results show that the suggested system can satisfy electricity and freshwater demand well. The lower loss of power supply probability (LPSP) or loss of water supply probability (LWSP) requires larger renewable installed capacity. At same threshold situation, the renewable configuration of LWSP is larger than that of LPSP. The performance comparison among different system structures implies that this system has lower renewable configuration and total dumped energy. Moreover, the coefficient of performance of heat pump (COP), the heat storage system capacity, the basic freshwater demand, the flexible energy bag volume and the humidifier seawater inlet temperature have obvious effect on system performance.