Experimental, modeling, and simulation approaches for underground hydrogen storage

Hydrogen can make a significant contribution to global climate goals by offering a clean and versatile energy carrier. Large-scale hydrogen storage is crucial for developing a sustainable hydrogen economy. However, due to its low density and high flammability, hydrogen storage limits its widespread adoption. Being able to understand and predict hydrogen flow in porous media during hydrogen injection-withdrawal cycles is critical to the successful implementation of underground hydrogen storage (UHS) projects. This chapter outlines different experimental methods, numerical models, and simulation techniques used in studying UHS. More specifically, experimental measurements of hydrogen-brine interfacial tension, rock wettability, hydrogen solubility and diffusion, microfluids, and hydrogen flooding at the core scale were illustrated. Various processes that govern the performance of UHS, including fluid hydrodynamics, geomechanics, geochemical reactions, and microbial activity, were comprehensively discussed. Additionally, factors affecting the hydrogen storage process, such as rock-fluid properties and operating conditions, were highlighted. Phenomena associated with UHS, such as viscous fingering, gravity override, hydrogen residual trapping, and gas diffusion and solubility, were portrayed in this chapter. Studying key factors of UHS such as hydrogen adsorption, diffusion, and solubility in reservoir fluids at the molecular level using molecular dynamics simulation was also summarized. An overview of UHS projects concludes this proposition.