HYDROGEN HAZARDSWhat Are the Risks of Hydrogen Vehicles in Tunnels?
In addition to electric vehicles, hydrogen-powered vehicles are also seen as an alternative to conventionally powered vehicles. Scientists have analyzed the risk and damage potential of hydrogen vehicles in tunnels and derived recommendations. Their conclusion? Any damage would be extensive, but its occurrence is unlikely.
In addition to electric vehicles, hydrogen-powered vehicles are also seen as an alternative to conventionally powered vehicles. However, an increase in the number of such cars with fuel cells (fuel cell electric vehicles – FCEVs) would also result in completely new hazard scenarios, especially in tunnels. In the HyTRA project, Graz University of Technology (TU Graz) has investigated what types of incidents involving hydrogen-powered vehicles in tunnels are realistic, what dangers arise for people and the tunnel structure, and what measures can be taken to minimize these risks. The project was funded by the Austrian Research Promotion Agency (FFG), the Federal Ministry for Climate Protection, Environment, Energy, Mobility, Innovation and Technology (BMK) and ASFINAG.
Low Probability of Occurrence, High Damage Potential
There is virtually no empirical data on real accidents involving hydrogen-powered vehicles in tunnels due to their low traffic share to date. Therefore, only a rough estimate of the probability of occurrence could be made based on experience with gas-powered vehicles, which indicated a low probability. In comparison, the potential extent of damage was analyzed in great detail on the basis of experiments from the EU HyTunnel-CS project, which ended in 2022. Due to the high energy density of hydrogen and the high pressure at which it is stored, FCEVs have a very high damage potential.
According to the current standard, hydrogen is stored in cars at a pressure of 700 bar and in lorries and buses at 350 bar. If damage occurs to a tank, a great deal of energy is quickly released; if hydrogen catches fire, it burns at temperatures of over 2000 degrees Celsius. Although the tanks are very robust and well protected against mechanical impact, they cannot withstand a rear-end collision with a lorry. This scenario should therefore be avoided as far as possible.
