Beyond Standards: Safety Assessment of Hydrogen and CNG High-Pressure Alternative Gaseous Fuel Filling Stations

Energy transition has established hydrogen and compressed natural gas (CNG) as key alternatives for reducing greenhouse gas emissions and promoting sustainable mobility in the transport sector. However, the safe deployment of this infrastructure is essential to ensure that decarbonisation strategies remain environmentally, socially and operationally sustainable. Filling stations handling flammable gases may release hydrogen or CNG into open environments where ventilation alone cannot always prevent unacceptable risk situations in populated and industrial areas. Although the current regulatory framework sets out essential design requirements, including safety distances, this article argues that risk management must go beyond minimum compliance, reconsidering the location of detectors, gas dispersion behaviour and the definition of hazard zones. The analysis takes into account the rapid dilution of these gases under open air ventilation conditions and supports a more risk-based approach to infrastructure planning. Since gas supply facilities operating at 25 MPa, the hazard zone from the vehicle receptacle is estimated at 3 m for hydrogen and 1.7 m for CNG. These findings contribute to a safer and more sustainable transport energy infrastructure.