Hydrogen-based mobility solutions could offer viable technology for sustainable transportation. Current research often examines single pathways, leaving broader comparisons unexplored. This comparative life cycle assessment (LCA) evaluates which vehicle type achieves the best environmental performance when using hydrogen from grey, blue, and green production pathways, the three dominant carbon-intensity variants currently deployed. This study examines seven distinct vehicle configurations that rely on hydrogen-derived energy sources across various propulsion systems: a hydrogen fuel cell electric vehicle (H2FCEV), hydrogen internal combustion engine vehicle (H2ICEV), methanol flexible fuel vehicle (MeOH FFV), ethanol flexible vehicle (EtOH FFV), Fischer-Tropsch (FT) diesel internal combustion vehicle (FTD ICEV) and renewable compressed natural gas vehicle (RNGV). Via both grey and blue hydrogen production, H2 FCEVs are the best options from the viewpoint of GWP, but surprisingly, in the green category, FT-fueled vehicles take over both first and second place, as they produce nearly half the lifetime carbon emissions of purely hydrogen-fueled vehicles. RNGV also emerges as a promising alternative, offering optimal engine properties in a system similar to H2ICEVs, enabling parallel development and technological upgrades. These findings not only highlight viable low-carbon pathways but also provide clear guidance for future targeted, detailed, applied research.

Decarbonising the transport sector is crucial, yet selecting the most suitable alternative fuels remains challenging. This study applies life cycle assessment to evaluate six alternative fuels, such as hydrogen, compressed natural gas, methanol, ethanol, Fischer-Tropsch gasoline, and diesel, against conventional gasoline, diesel, and grid electricity, focusing on global warming potential and acidification potential. Emissions were analysed using the Greenhouse gases, Regulated Emissions, and Energy use in Technologies model under two scenarios: current technologies (2025) and projected advancements (2050). The results indicate that, compared to gasoline, compressed natural gas reduces global warming potential and acidification potential by 27% and 23% in the short term, while gaseous hydrogen achieves reductions of 63% and 46% in the long term, respectively. These findings reinforce the theoretical foundation for transport sector decarbonisation and contribute to its sustainable development. Future research will broaden the assessment framework by incorporating complete vehicle life cycle analysis, evaluating additional alternative fuels, and integrating a wider set of indicators.