Investigation of Influencing Factors on Power Generation Performance in Reverse Electrodialysis

The importance of meeting energy demands from renewable sources is growing daily. Reverse electrodialysis (RED) is a membrane-based technology that produces energy using electrolyte solutions with different salinities. This study has generated energy from the RED system using the commercial Fujifilm Type II ion exchange membranes (IEMs). Many parameters affect the power generation performance of the RED system. This study systematically investigated the parameters, the presence of divalent ions and organic molecules, the electrolyte solution concentration, and the flow velocity. The flow velocity results indicated that energy efficiency increased with increasing flow velocity of the electrolyte solutions. The presence of divalent ions created uphill transport. The results showed that increasing the mole ratio of divalent ions in the feed electrolyte solutions dramatically decreased the RED system performance due to increasing resistances. The organic fouling test of the anion exchange membranes (AEMs) was carried out using a real humic and fulvic acid mixture under static conditions. The results indicated that fouling layers formed in the AEMs structure, and these layers decreased by 30% of RED performance. Lastly, the RED system's long-term performance was tested for 4 hours at a constant current density of 8 A/m2 before and after AEM fouling experiments. The results revealed the fouling layers severely reduced the power generation performance of the RED system.