Humidification-dehumidification desalination systems driven by thermal-based renewable and low-grade energy sources: A critical review

Thermal-based renewable and low-grade energy sources to operate humidification-dehumidification (HDH) desalination systems are critically reviewed. The investigated renewable energy sources are solar energy and geothermal energy. The low-grade energy sources such as the waste heat of photovoltaic thermal (PV/T) panels, refrigeration and heat pump systems, and power plants are also investigated. For each hybrid HDH with another driving system, the details of HDH construction, performance, hybridization method, and general observations are summarized and compared in tabular forms. Most of the studies focused on using solar energy and refrigeration and heat pump systems to drive HDH systems. The best performance indices (i.e., gained output ratio (GOR), freshwater production, and freshwater cost) can be obtained by the integration of HDH systems with power plants and then by geothermal energy, especially when a large quantity of freshwater is needed (>200 kg/h). Refrigeration systems and solar collectors can lead to higher GOR, medium water production, and higher cost. The application of PV/T results in the lowest water production. Despite the high performance of HDH driven by power plants and vapor-compression refrigeration systems, geothermal energy, solar collectors, and PV/T panels could be the right choices for hybridization with HDH systems in off-grid regions.