Preliminary hazard identification for qualitative risk assessment on onboard hydrogen storage and supply systems of hydrogen fuel cell vehicles

Due to the ever-increasing stringency of environmental policy requirements, hydrogen fuel cell vehicles (HFCVs), which are intended to serve as a substitute for conventional automobiles, are continuously evolving as a new promising technology. It is essential to conduct hazard identification as an early phase in the development of HFCVs in order to describe possible hazards and identify potential safety concerns. The onboard hydrogen storage and supply system is an essential component of HFCVs, serving to store hydrogen and provide it to the fuel cell system to guarantee its proper functioning. In this context, the research is conducted by establishing models of onboard hydrogen storage and supply system that reflected their specifications and elements. In this study, the methods of hazard and operability study (HAZOP) and failure mode and effect analysis (FMEA) are employed to identify and analyze the potential accident scenarios. The risk of each potential accident scenario, including whether to implement safety measures, is analyzed and classified as risk matrix. Medium- and high-risk scenarios in the absence of safety measures include accidental burst of the hydrogen cylinder, debonding of plastic liners and metal bosses, release of hydrogen from a thermally activated pressure relief device or pressure relief device, tiny release of hydrogen from improperly attached tube fittings, and small release of hydrogen from valves with seal failures. Comparing the findings of risk matrices with and without safety measures confirms that the safety measures lower the risk levels of the onboard hydrogen storage and supply systems to a tolerable level.