Application of Quantitative Risk Assessment to Hydrogen Transport Plants

The scientific community agrees in the need to limit the anthropic emissions of greenhouse gases into the atmosphere in order to mitigate the causes of climate change that has occurred in recent years. In order to fulfill this objective an extended decarbonization of industrial processes and an energy transition towards zero carbon emission sources are needed. Hydrogen currently represents one of the most promising solutions to achieve these goals, since it can be produced with low-emission technical solutions and may be used to produce mechanical or electric energy without the production of CO2. In the perspective of using hydrogen as an energy carrier, future plans to ensure its large-scale distribution concern the possibility to convert the currently existing natural gas grid infrastructures to the transport of hydrogen. However, there is currently a lack of technical regulations, codes and standards to ensure a safe design and operation of these infrastructures in case of their hydrogen conversion. For this reason, quantitative risk assessment (QRA) may represent an important tool to evaluate safety of hydrogen plant and to investigate if conversion to hydrogen of existing energy infrastructures could be considered sufficiently safe. Therefore, in this paper, critical issues and peculiarities related to hydrogen in the application of the QRA are examined. Furthermore, a case study was developed to assess the risk profile obtained considering an accidental release from a typical transport plant facility. Sensitivity analysis of results to different modeling parameters and benchmarking with those obtained for natural gas have been carried out, in order to highlight the potential safety concerns in case of hydrogen conversion of existing natural gas grid infrastructures.