Because the energetic requirements of BPM-ED EMCC are critical to the optimization and implementation of these systems, voltage contribution analysis of the BPM operating in 1 M KHCO3 and simulated seawater were conducted to determine the major sources of power loss in the BPM-ED system. As expected, the thermodynamic potential required to drive the pH gradient across the CL via electric-field enhanced water dissociation (Section S1.2) makes up the largest contribution to the applied potential. The next largest potential loss in the system is the kinetic overpotential for the water dissociation in the CL (Section S1.2). Unfortunately, while the thermodynamic requirements cannot be altered, the kinetic overpotential can be lowered by employing a better water-dissociation catalyst. For the 1 M KHCO3 case, bubble coverage losses also make up a significant portion of the applied potential, particularly at high current densities, and those could be managed by better controlling flow as discussed in section 3.5 or through other bubble-mitigation strategies. Lastly, ohmic losses through the CEL and AEL are quite low relative to other losses, but do increase with current density and will likely become critical if the BPM-ED system is to operate at currents approaching 1 A cm -2 . Although minor, these losses can be decreased by improving ionic conductivity of the AEL and CEL. This appliedvoltage breakdown highlights that the greatest areas for improvement in the BPM-ED performance are in improving the water dissociation catalyst and in implementing bubblemanagement strategies.