Determination of ultimate operating pressure for hydrogen storage in high impurity salt caverns based on gas-structure-interaction model

Salt cavern hydrogen storage (SCHS) represents one of the most promising options for the large-scale underground storage of hydrogen. A complex gas-structure interaction (GSI) occurs between hydrogen as a gas and salt caverns. In this paper, a hydrogen permeation GSI model considering creep of surrounding rock is proposed, and the effects of the variation of the lower and upper limits of internal hydrogen pressure (IHP) on the tightness and stability of hydrogen storage in the S6 salt cavern are discussed. The findings indicate that as the lower limit of IHP diminishes, both the hydrogen permeability and the maximum displacement exhibit an upward trend. Conversely, as the upper limit of IHP rises, the hydrogen permeability increases while the maximum displacement declines. For S6 salt caverns, it is imperative that the upper limit IHP does not fall below 7 MPa, and the lower limit IHP should not be less than 16 MPa and not be more than 18 MPa. Furthermore, the permeation percentage of SCHS increases with the interlayer permeability, exhibiting a clear nonlinear relationship. When the permeability of the interlayer is 1e −18  m 2, the permeation percentage after 10 years of operation is 21.3%, which is more than twice the critical value. This indicates that S6 cavern hydrogen storage is not feasible when the interlayer permeability is greater than 1e −18  m 2.