Temperature-enhanced pressure retarded osmosis powered by solar energy: Experimental validation, economic consideration, and potential implication

Temperature-enhanced PRO (T-PRO) has been demonstrated to enhance the PRO performance via one system/module-scale mathematical model, but its techno-economic availability is still uncertain. As such, T-PRO was experimentally investigated in the lab-scale setup and its economic benefit was evaluated via utilizing solar energy as the thermal source. The experimental investigation showed that both optimal operating pressure and corresponding water flux increased from 12 bar and 3.74 LMH to 16 bar and 7.94 LMH when the operating temperature increased from 20 to 30 °C, thereby rendering an increase in power density from 1.25 to 3.53 W/m2 by 1.82 times and validating that the contribution of high operating temperature on energy generation was derived from increased operating pressure and water flux. Furthermore, the economic feasibility of T-PRO was assessed via one developed economic evaluation model based on solar linear Fresnel collectors. Evaluation results showed that the economic benefit of T-PRO could not cover the expenditure of thermal power, thus a standalone T-PRO system powered by solar energy was not feasible under current conditions. But, if these high-temperature and low-salinity solutions discharging from T-PRO can enter some thermal desalination systems, additional thermal power in T-PRO would reduce the thermal input in a further thermal desalination system. Therefore, T-PRO powered by solar energy must be integrated with thermal desalination technologies under the high cost of solar energy.