Hydrogen Flooding of a Coal Core: Effect on Coal Swelling

Abstract

Hydrogen is a clean fuel which has the potential to drastically decarbonize the energy supply chain. However, hydrogen storage is currently a key challenge; one solution to this problem is hydrogen geo-storage, with which very large quantities of H2 can be stored economically. Possible target formations are deep coal seams, and coal permeability is a key parameter which determines how fast H2 can be injected and withdrawn again. However, it is well known that gas injection into coal can lead to coal swelling, which drastically reduces permeability. We thus injected H2 gas into a coal core and measured dynamic permeability, while imaging the core via x-ray micro-tomography at reservoir conditions. Importantly, no changes in coal cleat morphology or permeability were observed. We conclude that H2 geo-storage in deep coal seams is feasible from a fundamental petro-physical perspective; this work thus aids in the large-scale implementation of a hydrogen economy.