Underground salt cavern storage is recognised as one of the most suitable technologies to meet the challenges of the new European energy system. With the advantage of being mostly impermeable to gases, salt caverns are currently the only structures used to store hydrogen on a massive scale underground. This paper studies the consequences of a rapid withdrawal of hydrogen on the mechanical stability of a salt cavern. Gaseous hydrogen cooling could generate rock salt dilation, cavern closure and tensile stresses at the cavern wall. Numerical computations using the finite element method help to evaluate the geomechanical consequences of a rapid depressurisation in a selected cavern for an underground hydrogen storage demonstrator in France.
Europe has made the development of green hydrogen a priority in its strategy to address climate change. This ambition paves the way for a decarbonised hydrogen industrial sector. Hydrogen as an energy vector provides viable solutions to replace polluting and carbon-emitting fossil fuels. In recent decades, underground hydrogen storage in salt caverns has emerged and is already in operation in the United Kingdom and the United States. Underground storage of large quantities of gaseous hydrogen in salt caverns (based on the example developed for natural gas by providing seasonal capacity) is a solution to promote the decarbonisation of energy by making renewable hydrogen available anytime for mobility, industry and domestic heating.
The European HyPSTER project (2021-2023), coordinated by Storengy, aims to demonstrate the feasibility of operating underground hydrogen storage in salt caverns on an industrial scale, i.e. to ensure storage replication across the European Union. In this context, a pilot site is planned in France in 2023 at Bresse Vallons (Ain) for storage replication on France's most studied salt cavern (Djizanne et al. 2022). The control of industrial risks around this emerging technology and its environmental impact remains essential for public acceptance. The safety of hydrogen storage includes tightness issues but also structural stability. This paper focuses on the mechanical stability of a salt cavern submitted to a rapid gas depressurisation following a fast hydrogen withdrawal from the cavern.
