Publication

The potential climate benefit of liquidhydrogen jet fuelversus conventional jet fuel strongly depends on the hydrogen fuelpathway and is sensitive to the estimated difference in contrail cirrusimpacts. The aviation industry faces a formidable challenge tocap its climateimpact in the face of continued growth in passengers and freight.Liquid hydrogen (LH2) is one of the alternative jet fuelsunder consideration as it does not produce carbon dioxide upon combustion.We conducted a well-to-wake life cycle assessment of CO2 emissions and non-CO2 climate change impacts per passenger-distancefor 17 different hydrogen production routes, as well as conventionaljet fuel and biofuels. Six other environmental and health impact categorieswere also considered. The Boeing 787-800 was used as the referenceaircraft, and a range of flight distances were explored. Contrailcirrus contributes around 81 & PLUSMN; 31% of the combustion climateimpacts for LH2, compared to 32 & PLUSMN; 7% for conventionaljet fuel, showing that research is needed to reduce uncertainty inthe case of LH2. The life cycle impacts of the two dominantcommercial LH2 pathways are on average 8 and 121% largerthan conventional jet fuel. Some novel LH2 pathways doshow considerable potential for life cycle climate impact reductionsversus conventional fuel (up to -205 & PLUSMN; 78%). LH2 from renewable energy is not climate neutral, though, at best -67 & PLUSMN; 10% compared to conventional over the life cycle.