Energy Consumption in Batch-Mode Capacitive Deionization

Capacitive deionization (CDI) is a water desalination technique in which salt ions are removed from brackish water by flowing through a spacer channel with porous electrodes on each side. Upon applying a small voltage difference between the two electrodes, cations move to and are accumulated in electrostatic double layers inside the negatively charged cathode and the anions are removed by the positively charged anode. Therefore, one of the advanced merits of CDI is the low driven energy by compared to other desalination technologies. Inspired this, we have performed the calculation on energy consumption of activated carbon based CDI in different operation conditions. The results show that the energy consumptions are significantly related to cell voltage as well as solution concentration. Furthermore, the round trip efficiency as a vital indication in terms of energy consumption have been introduced and discussed as well.