Salinity gradient power generation remains largely untapped renewable energy resource. One of the most promising membrane-based methods to capture salinity gradient energy is reverse electrodialysis (RED), which generates power via the transport of the positive and negative ions in the water through series of alternating cation exchange membranes (CEMs) and anion exchange membranes (AEMs). In an effort to advance the development of RED system for efficient and optimal energy conversion, firstly a new RED model was developed to simulate realistic salinity conditions in the natural water environment (i.e., coexisting monovalent and multivalent salt ions) and further tested under different flow rate ratios (saline water flow over freshwater flow) and intermembrane distance ratios to maximize the power generation. Our results indicated that the power density was greatly improved with higher flow rate ratio (11%) and intermembrane distance ratio (74%). Secondly, a new type of nanocomposite CEMs was synthesized and successfully performed in RED. The results showed that the combination of functionalized iron (III) oxide with the sulfonated poly (2,6-dimethyl-1,4-phenylene oxide) polymer proved to have great potential for power generation by RED. An optimal amount of Fe2O3-SO42- (0.5-0.7 wt%) enhanced the key electrochemical properties including a permselectivity of 87.65% and an area resistance of 0.87 O cm2. Remarkably, the nanocomposite membrane containing 0.7 wt% Fe2O3-SO42- achieved a maximum power density of 1.3 W m-2, which is relatively higher (9%) than that of the commercially available CSO (SelemionTM, Japan) membranes. The goal of the present work is to optimize the key operational and structural elements of the RED system to better harness the natural power source for sustainable energy generation.

Optimization of reverse electrodialysis for salinity gradient power generation: Development of process-based model and synthesis of novel nanocomposite ion-exchange membranes

247th National Meeting (2014)

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