Reliability-based design tool for gas storage in lined rock caverns

The transition to a fossil-free energy matrix may require large quantities of hydrogen gas, which could be stored efficiently in underground lined rock caverns (LRCs). Since the consequences of failure can be catastrophic, the LRC design needs to have a small failure probability. However, the current deterministic design practice for LRCs limits the possibility to stringently address geotechnical uncertainties. In this paper, a reliability-based design tool is presented for LRCs. The adaptive directional importance sampling (ADIS) method, which requires a relatively small number of samples, is used with a 3D finite element (FE) model to evaluate small probabilities of failure. An illustrative example based on the LRC in Skallen, southwestern Sweden, demonstrates the implementation and applicability of the developed design tool. The considered uncertainties are related to the geological conditions and the steel lining. The results show that the reliability of this LRC design meets the expected safety requirements. Considering different geological conditions with correlations, at least good quality rock mass is needed for the LRC design. An additional sensitivity analysis is performed to study the potential influence of corrosion and hydrogen embrittlement, showing that the LRC design could meet safety requirements for a lower category of the weld quality.

Automated summary

This paper presents a reliability-based design tool for underground lined rock caverns (LRCs) for storing hydrogen gas. The adaptive directional importance sampling (ADIS) method is used with a 3D finite element (FE) model to evaluate small probabilities of failure. An illustrative example based on an LRC in Skallen, southwestern Sweden, demonstrates the implementation and applicability of the design tool. The results show that this LRC design meets the expected safety requirements, with at least good quality rock mass needed for different geological conditions.