Risk-based approach for safe terminal operation and route planning of on-road hydrogen distribution network

Abstract

Hydrogen is a critical energy carrier in the transition to sustainable energy, but its properties such as high diffusivity, wide flammability range, and low ignition energy, present unique safety challenges during transportation. This study aims to improve on-road hydrogen transport safety by developing a dynamic, traffic-dependent risk assessment framework for both Compressed Gaseous Hydrogen (CGH₂) tube trailers and Liquid Hydrogen (LH₂). A key advancement in this study is the use of dynamic occupancy data, capturing variations in traffic density throughout the day, instead of relying on average traffic density to estimate ignition source distribution. Additionally, a qualitative Hazard and Operability (HAZOP) study was conducted for a potential central distribution terminal in Fort Saskatchewan, Alberta, Canada, to systematically identify process hazards during the loading of hydrogen on-road carriers. Results reveal that the ignition probability for minor CGH2 leaks significantly increases with road occupancy, rising from 0.003 at 0.1 % to 0.149 at 5 %, emphasizing the importance of scheduling transport during off-peak hours Vapor Cloud Explosions (VCE) from LH2 extend up to 257 m, compared to 122.42 m for CGH₂, underscoring the need for stricter land-use planning in densely populated areas. The analysis suggests prioritizing lower-traffic rural routes, which exhibit lower release frequencies (e.g., 1.80E-05 per year), over high-traffic urban routes with higher release frequencies (e.g., 6.47E-05 per year).