Conversely, the 1 and 0.5 M KHCO3 cases possess lower energy intensities due to higher concentrations of HCO3 -anions in the catholyte boundary layer for reaction, maintaining energy intensities near 100 kJ mol CO2 -1 even at current densities of 100 mA cm -2 . 0.5 M KHCO3 possesses a lower energy intensity due to its higher coulombic efficiency at high current densities. These energy intensities compare well with thermal processes, and the current densities achieved far exceed those demonstrated for other EMCC processes. The coulombic efficiency of sorbent regeneration, in terms of the transference number for CO3 2-at the anolyte boundary, is nearly 100% for 1 and 0.5 M KHCO3 (Figure ). As stated previously, this is likely due to an increased space time for HCO3 -conversion into CO3 2-. The ability for the AEL to exchange with both HCO3 -and water-dissociation-generated OH -enables a high activity for these ions to react and form CO3 2-in the anolyte boundary layer and within the AEL and CL. The buffer reactions in the simulated seawater BPM are still limited by HCO3 - concentration, but the conversion efficiency remains > 30% at all current densities (Figure -