Hydrogen Flooding of a Coal Core: Effect on Coal Swelling

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are deep coal seams, and coal permeability is a key parameter which determines how fast H2 can be injected and withdrawn again.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. Plain Language Summary 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. Earlier it has been shown that coal can adsorb and thus storage large quantities of hydrogen. Here we now demonstrate experimentally that coal permeability (and thus hydrogen injectivity and withdrawal capacity) is not affected by hydrogen flooding. 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. Key Points Hydrogen geo‐storage in deep coal seams is feasible from a flooding and adsorption perspective Hydrogen flooding does not cause any measurable coal swelling under deep coal seam conditions Coal permeability is not affected by hydrogen flooding under deep coal seam conditions