Performance and cost analyses of hybrid diesel-photovoltaic powered small brackish water reverse osmosis system in Saudi Arabia

The need for water is certainly very alarming in the Middle East and North Africa (MENA) region where water demand for domestic, agriculture, and industrial applications continue to increase, and on the other hand, water resources are increasingly becoming scarce (low precipitation and depletion of renewable groundwater). Inland desalination process in off-grid or remote areas con-tributes a significant portion to the water supply in Saudi Arabia. However, inland desalination systems have many challenges to be well implemented such as limited water distribution, water transmission cost from seawater desalination plants to the inland area. Many wells in Saudi Arabia have relatively high salinity water, which is not directly usable. This study aims to find the best hybrid diesel-photovoltaic powered reverse osmosis (RO) system to desalinate brackish water that has 6,000 ppm salinity for a remote area near Ummluj City in the Kingdom. Each RO system produces 202 m3/d for two purposes: drinking and household purposes. A batch mode that oper-ates 5 h/d is studied. The hybrid system composed of conventional and renewable energy sys-tems driven brackish RO system are modelled using ROSA and HOMER software. Besides, the advantages of adding a pressure exchanger (PX) and a second-stage are investigated. Further, the effect of the fuel price on the cost of water production is analysed. It was found that add-ing a second storage tank for household applications with 1,000 ppm reduces the levelized cost of water by 11%. Furthermore, using a pressure exchanger leads to 26% reduction in the spe-cific energy consumption (SEC) while adding a second-stage reduces the SEC by 22%. However, adding PX is economically feasible for fuel price higher than 40 USD/L.