Benchmark Analysis of Accident Modelling Software Applied to Hydrogen Storage.

Global greenhouse gas emissions have surged to unprecedented levels, prompting a strong focus on decarbonization. Hydrogen, especially when produced renewably, emerges as a promising CO2-free energy vector for industry, transport, and power sectors. However, the transition to hydrogen involves significant technical challenges, particularly in continuous production and safe storage. Classified as a hazardous substance under the SEVESO III Directive, hydrogen poses risks of major accidents, necessitating rigorous Quantitative Risk Assessment (QRA). Accurate consequence estimation is critical for reliable risk assessment. This study conducted a benchmark analysis of Phast, HyRAM, and ALOHA software tools to evaluate their capabilities in modelling the dispersion and ignition of gaseous hydrogen from pressurized tank leaks, focusing on the accuracy of their results. Real-world experimental data from three studies were used to validate simulation outcomes, covering pressures from 60 to 400 bar and hole diameters from 0.5 mm to 52.5 mm. Assumptions were made for missing parameters, including weather conditions, with ambient temperatures set at 10°C for night-time and 20°C for daytime experiments, and atmospheric stability classified using the Pasquill method. ALOHA demonstrated significant limitations in this study. It was unable to produce results for most experimental studies involving small and medium-scale hydrogen jets because it does not display distances shorter than 10 meters and is restricted to simulating vertical jet fires only. The comparison of Phast and HyRAM revealed that both tools generally underestimated hydrogen concentrations, with Phast performing slightly better than HyRAM, especially at higher concentrations. Atmospheric stability influenced dispersion but not jet fire characteristics. Both tools tended to overpredict flame length, except in the smallest release hole simulations. For large-scale jet fires, Phast overpredicted radiation, while HyRAM underpredicted it. In a QRA framework of hydrogen jets from pressurized tanks, this study suggests that using Phast is preferable due to its more accurate results. However, further validation of the software for large-scale jets is necessary.