Thermo-economic analysis of a hybrid system based on combined heat - isobaric compressed air energy storage and humidification dehumidification desalination unit

Abstract

To solve the problem of electricity and fresh water supply in different low-efficiency independent systems in coastal areas or remote islands, a hybrid system based on energy cascade utilization principle is proposed for both small-scale electricity and fresh water supply purposes. Such hybrid system is made up by the combined heat - isobaric compressed air energy storage (CH-ICAES) and the water-heated humidification dehumidification (HDH) desalination unit. Meanwhile, the CH-ICAES is a synthesis of ICAES and power to heat (PtH) technologies. In operation, the low-grade heat from CH-ICAES charging and discharging is used to produce fresh water in HDH. The simulated results show that the gained-output-ratio (GOR) and total produced fresh water mass in a roundtrip cycle at design condition are 2.0678 and 851.77 kg, respectively. Meanwhile, the levelized cost of storage (LCOS) and levelized cost of water (LCOW) are 35.45 cents/kWh and 0.57$/ton, indicating a competitive economic performance. Moreover, the GORs in charge and discharge are different due to the non-uniform heat source conditions. In addition, the humidifier inlet seawater temperature, the effectiveness of humidifier and dehumidifier, the relative humidity of dehumidifier inlet air, the HDH operation pressure and some parameters of CH-ICAES have significant effect on hybrid system performance.