(545ae) Design of an Electrochemical Cell for Desalination of Seawater

With rapidly increasing water-stressed regions and global fresh water demand rising at an alarming rate, there is a need to develop an efficient technology to supply fresh water. About 70% of earth being seawater, one of the obvious solutions to meet the freshwater crisis is desalination of seawater. One of the biggest challenges here is that seawater is heavily saline and must be desalinated to about 99% in order derive any application from it such as irrigation or drinking. Present technologies used commercially for seawater desalination are Reverse Osmosis (RO) are Multi-Stage Flash Distillation (MSF). However, there is a trade-off between energy efficiency and salt rejection efficiency in these methods. In the present work, we propose a stack-type electrochemical cell employing bipolar membranes to desalinate seawater. The cell stack of a bipolar membrane, anion-exchange membrane, cation-exchange membrane, and bipolar membrane divide seawater into a brine stream and a clean water stream by electrodialysis. The feasibility of this design was analyzed using COMSOL Multiphysics. The simulation results show that a stacked arrangement of such cell can successfully reach a desalination efficiency of 99% at near neutral pH. To operate such a system renewably, the power of operation may be extracted from a solar cell device. A detailed balance (Shockley-Queisser limit) analysis was performed to determine the current-voltage characteristics of multijunction light absorbers. An operating point (current density and voltage) was obtained for ideal single, double, and triple junction light absorbers for the electrochemical desalination of seawater. Making an integration with solar cell will make this design portable and would be easily accessible in the water-stressed regions.