Power Generation Optimization of Reverse Electrodialysis: Effects of Key Operating and Design Parameters

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Salinity gradient power (SGP) via reverse electrodialysis (RED) is a promising renewable energy source; however, maximizing efficiency requires balancing complex electrochemical and hydraulic variables. This study systematically investigates the effects of key operating and design parameters on RED power generation to improve energy efficiency. Laboratory-scale RED experiments are conducted by varying the concentrations of high-concentration (HC) and low-concentration (LC) NaCl solutions, space velocity, the number of ion-exchange membrane (IEM) pairs, and flow channel thickness. The results show that power density increases with concentration ratio and absolute solution concentration, with optimal performance achieved at HC concentrations of 1-2.5 M, LC concentrations of 0.02-0.05 M, and a concentration ratio above 50:1. An optimal space velocity of 0.25 1/min is identified. Increasing the number of IEM pairs enhances power density, while flow channel thicknesses of 1-2 mm minimize resistance. Under optimized conditions, a maximum power density of 0.446 W per square meter is achieved.