Electric Power Generation with Reverse Electrodialysis

The computer simulation program of a practical scale reverse electrodialysis process has been developed based on the program for saline water electrodialysis. The program is applied to compute the performance of an industrial-scale reverse electrodialysis stack (effective membrane area S = 1 m × 1 m = 1 m2, cell pair number N = 300 pairs). The stack operatingconditions are optimized. Seawater and brackish water are supplied to compute the overall membrane pair characteristics, ion and solution flux across a membrane pair, ion transport efficiency, generation efficiency, electric current leakage, stack electric resistance, stack voltage, external current, electric power, power density, pressure drop, limiting current density, and etc. When seawater (35000 ppm) and brackish water (1000 ppm) are used, the maximum power density is 0.85 W/m2 (15 °C), 1.10 W/m2 (25 °C) and 1.35 W/m2 (35 °C). Membrane electric resistance is less than brackish water electric resistance. Electric current leakage increases the electric power generation of the RED unit. Limiting current density is very large, so the unit is operated stably. By arranging 12 stacks, a small-scale reverse electrdialysis plant (N= 12×300 = 3600 pairs) is assembled. The plant is operated to compute the performance changing external electric resistance.