Electric field-enhanced CO2 dissolution and adsorption for geological carbon sequestration in saline aquifers

Abstract

Electric fields can enhance CO₂ sequestration in saline aquifers by influencing both dissolution and adsorption, with effects dependent on the field’s orientation, strength, and the rock surface’s wettability. Molecular dynamics simulations reveal that perpendicular electric fields increase CO₂ dissolution in water by up to 41.74% on hydrophobic rock surfaces through promoting CO₂ desorption, while on hydrophilic rock surfaces, they boost CO₂ adsorption by up to 8.27%. These effects intensify with increasing field strength. In contrast, parallel electric fields slightly enhance CO₂ adsorption on hydrophobic surfaces but decrease it on hydrophilic ones. The underlying mechanism involves the electric field-induced reorientation of water dipoles, aligning or disrupting hydrogen bonds. In hydrophobic systems, perpendicular fields promote CO₂ diffusion into the water phase by inducing perpendicular hydrogen bonds. On hydrophilic surfaces, these fields disrupt hydrogen bonds and non-boned interactions between water and the surface, leading to water detachment and promoting CO₂ adsorption. Parallel fields induce parallel hydrogen bonds, impeding CO₂ diffusion and reducing its dissolution into the H₂O phase (or adsorption onto the rock surface). These findings highlight the potential of electric fields to enhance geologic CO₂ sequestration in saline aquifers.