Reverse electrodialysis (RED) is a nonpolluting sustainable technology that converts the free energy of mixing of two solutions with different salinity directly into electrical energy. Although the theoretical potential is high, the practical power output obtained is limited yet due to concentration polarization phenomena and spacer shadow effects. In this work we combinetheoreticalcalculationswithdirectcurrentandalternating current experimental stack characterization methods to quantify the contribution of concentration polarizationphenomena, spacer shadow effects and stack resistance in RED under different hydrodynamic conditions in a temperature range from 10 to 40°C to show the practical potential of RED. Concentration polarization phen...