Effect of MgCl2 on energy generation by Reverse Electrodialysis

One of the membrane-based technique for harvesting salinity gradient energy is Reverse Electrodialysis (RED). Most of the studies in literature are based on utilizing river and seawater by mimicking them with NaCl solutions. However, real solutions contain many different ions; this study deals with the impact of Mg2+ ion on power density (Pd). Investigations have been carried out using six solutions of NaCl and MgCl2 prepared in varying compositions from 0 % to 100 %. Increasing Mg2+ concentration resulted in a remarkable decrease of Pd and open circuit voltage (OCV), and in a significant increase in stack resistance Rstack. Electrochemical impedance test (EIS) and ion chromatography analysis helped to clarify reasons for loss of power. In particular, it was found out that dominant negative contribution is due to increasing Cation Exchange Membrane (CEM) resistance in the presence of Mg2+.