Natech Risks in Hydrogen Repurposed Pipelines: Triggering Events, Vulnerabilities, and Mitigation Strategies

The use of clean hydrogen to decarbonize hard to abate sectors has been under consideration in the context of the global energy transition, and repurposing natural gas pipelines has emerged as a cost-effective option for hydrogen transport. While this approach leverages existing infrastructure, it also introduces safety challenges, one of them being new weaknesses in natural hazard triggered technological (Natech) accidents. This paper provides a theoretical framework to understand Natech risks in hydrogen repurposed pipelines by identifying the main triggering events, highlighting the specific vulnerabilities of hydrogen compared to natural gas, and outlining mitigation strategies. The study reviews academic literature to select and analyze relevant natural hazards affecting Europe that can initiate pipeline failures. Hydrogen's characteristics, such as its wider flammability range, lower ignition energy and propensity for material embrittlement, amplify both the probability of release and the severity of consequences. The paper draws on strategies from structural and organizational risk reduction to examine targeted accident prevention and mitigation measures. By mapping hazard-vulnerability-mitigation linkages, this paper aims to support operators, regulators, and researchers in developing more resilient hydrogen transport networks. The findings emphasize that hydrogen's distinct physical and material interactions require dedicated risk reduction strategies.

Keywords: Natech risk, Hydrogen pipelines, Natural hazards, Risk reduction, Accident scenarios, Floods, Landslides, Lightning, Cold wave.