CFD-based risk assessment of underground hydrogen storage in salt caverns

The transition to a hydrogen economy requires efficient large-scale hydrogen storage solutions. Despite the appeal of hydrogen due to its low density, efforts to improve storage density are necessary to minimize capital and operating costs. Underground hydrogen storage (UHS), particularly in salt caverns, offers promising advantages, including high energy densities and low construction costs. Large scale H2 storage coupled to significant H2 safety issues requires risk evaluation. This work focuses on comprehensive risk assessment for UHS that addresses both the limitations of empirical models and specific hydrogen storage safety issues. We specifically focus on addressing criticisms related to the applicability of empirical models to gases with high diffusivity such as hydrogen. Advanced models, computational fluid dynamics simulations (CFD), are used to capture dispersion and mixing of hydrogen with the aim to reduce the underestimation of risks associated with hydrogen systems. Through a case study focused on a worst-case scenario due to rupture at the ground of riser pipe connecting the salt cavern to the ground, the risk assessment associated to the UHS is carried out. The main findings highlight the importance of comprehensive risk assessment methods based on CFD simulations, to ensure the safety and reliability of underground hydrogen storage systems to facilitate the transition to a sustainable hydrogen economy. Particularly, the effect of confinement was investigated in terms of risks as well as regarding the particular 3D dispersion of hydrogen. Results were compared with those obtained in a previous work with empirical models and the risk resulted acceptable (IR < 10−6 years−1) once adequate safety functions were added.