Local concentrations and fluxes in the BPM from the simulations elucidated that alkali cations and (bi)carbonates are the dominant ion and primary charge carrier in the BPM at low current densities, with water-dissociation generated H + and OH -becoming the dominant ions at high current densities once buffering (bi)carbonate anions are consumed by homogeneous reaction. Furthermore, the energy intensity for CO2 desorption as a function of applied current density is also determined, for which the model reveals that the low concentration of (bi)carbonates in simulated seawater leads to mass-transport limitations and consequently high energy intensities for CO2 recovery at high current densities for BPMs immersed in seawater.