First, it is important to note that due to mass-transport limitations in the seawater case as discussed above, bubbling only occurs for the BPMs exchanged with KHCO3. Analysis of the bubble coverage in these simulations (Figure ) shows that the bubble coverage of the BPM exceeds 30% at high current densities due to super saturation of the electrolyte. This high bubble coverage is consistent with visual observation of the CEL during operation (Supporting Video S1). Additionally, the analysis of the energy requirements with and without losses due to bubble coverage reveals that bubble effects account for nearly 10 kJ mol -1 of energy loss (Figure ) for both KHCO3 cases at 100 mA cm -2 . Therefore, managing bubbles is indeed crucial to improving energy efficiencies for BPM-ED EMCC. Previous knowledge from water electrolysis shows that bubble coverage losses can be ameliorated by controlling flow rate, increasing gas headspace pressure, or by employing a surfactant to reduce surface tension and bubble size. The BPM morphology and surface chemistry can also be modulated to alter the wettability and coverage of bubbles on the surface. To highlight the importance of bubble management, further experiments were performed.