External electric field enhances CO2 geological Storage: A molecular dynamics simulation

Abstract

The microscopic understanding of adsorption and storage of CO2 in minerals is of great significance for large-scale geological storage of CO2. The behaviors of the H2O − CO2 system absorbed on the kaolinite surfaces with oscillating and static electric fields were investigated by the non-equilibrium molecular dynamics simulation. The results show that the H2O molecules will adsorb onto clay surfaces and reduce the adsorption of CO2, which results in lower amounts of geological storage of CO2. However, the applied external static electric fields can break hydrogen bonds which formed between H2O molecules and clay surface, and thus promote the desorption of H2O and geological storage of CO2. The static electric fields are more pronounced in enhancing CO2 geological storage with an extra 15.58 % when the surface is vertical to the electric field direction. Meanwhile, the initial dipole orientation of H2O in the adsorption phase, which is parallel to the surface, decides that electric fields are more efficient on the surface vertical to the electric field direction. This research will be helpful to understand how electric fields promote CO2 geological storage on the molecular level.