The feasibility of hydrogen storage in aquifers: A molecular dynamics simulation

Abstract

Geological hydrogen storage could be an effective method for solving energy demand and climate change challenges. We focus on hydrogen diffusion in carbonate slits via molecular dynamics under subsurface conditions. We investigate the influence of pore size, moisture content, and salinity on hydrogen diffusion process. The results demonstrate that high moisture content reduces the diffusion coefficient of hydrogen due to the form of water bridge and hydrogen cluster. The impact of salinity is observed only under high moisture content conditions. Specially, CaCl2 and MgCl2 are more suitable than NaCl for hydrogen storage. Hydrogen storage is more suitable in lower NaCl concentration while it is more suitable in a higher Na2SO4 concentration. Because interfacial tension of hydrogen-salt solution could be affected by ion concentration. These results demonstrate that hydrogen diffusion could be regulated by changing salinity for high water cut reservoir. This job could provide valuable guidance for underground hydrogen storage.