From accidents to safer hydrogen systems: Exploring failures and safety barriers at hydrogen refuelling stations in Japan

As part of the global transition to low-carbon energy systems, the accelerated construction of Hydrogen Refuelling Stations plays a vital role in supporting the uptake of hydrogen-powered transport. Ensuring the safety and reliability of these facilities is therefore increasingly critical. While various risk assessment models have been developed, the systematic analysis of real-world operational experience is still underrepresented in the literature. This study addresses that gap by expanding the analysis of the Japanese KHK accident database through a newly developed typology that captures not only the causes and types of hydrogen releases but also the role of safety barriers and emergency responses. The findings highlight that most hydrogen leakage accidents occurred during normal operation, with a significant number also arising during inspections and testing. Common causes included equipment failures, particularly in valves, joints, and seals, as well as human errors. Dispensers, compressors, and storage units were frequently involved. Although fixed and portable detectors were vital for leak identification, reliance on low-tech methods and operator vigilance remained essential due to occasional detection failures. Overall, the study underscores the need for both technical and organisational improvements, such as system redundancies, revised maintenance practices, and institutional learning, to enhance overall hydrogen station safety. • Valves, seals, and joints were the top sources of leakages in hydrogen stations. • Dispensers and compressors were most often involved in hydrogen leak accidents. • One-third of leaks originated from safety systems, prompting reliability concerns. • Fixed and portable sensors were key, but 1 in 7 leaks relied on human detection. • Most responses involved part replacements and updated maintenance protocols.