Numerical assessment of the environmental impact of hydrogen-powered vehicles under realistic driving conditions

This study evaluates the cradle-to-grave (CTG) greenhouse-gas (GHG) emissions of a light-duty hydrogen internal combustion engine (HICE) vehicle by combining vehicle simulations, which estimate fuel consumption and GHG emissions under real-world driving conditions, and a life-cycle assessment (LCA) covering the vehicle’s lifetime up to 2050 under four different hydrogen production scenarios. The environmental performance of this vehicle is compared with that of its gasoline-fueled counterpart, considering both conventional and hybrid powertrains, to assess the potential of hydrogen fuel and hybridization to decarbonize the road-transport sector. The results show that HICE vehicles can achieve substantially lower CTG GHG emissions than their gasoline counterparts, although their environmental performance is highly dependent on the hydrogen production pathway. Under the assumptions adopted for the 2050 scenarios, SMR-based hydrogen production pathways incorporating CCS and biogenic feedstocks exhibit the lowest life-cycle GHG emissions. However, when considering the worst-case scenarios under maximum uncertainty, the situation is reversed, with the scenarios dominated by renewable water electrolysis yielding the lowest emissions, suggesting that these findings should be interpreted with caution. Hybridization generally improves fuel efficiency, but its environmental benefits strongly depend on the carbon intensity of hydrogen production and driving conditions, with potential advantages for the selected hybrid architecture only under urban driving. These results highlight the importance of considering representative driving conditions when evaluating the environmental performance of alternative fuels and powertrain configurations, and demonstrate the value of linking vehicle-level driving-cycle analysis with LCA to assess their life-cycle GHG emissions.