Comparative environmental life cycle assessment and operating cost analysis of long-range hydrogen and biofuel fueled transport aircraft

Abstract

The aviation industry is currently experiencing a social shift in the attitude towards flying due to the increasing awareness of the impact on climate change. This has led governments and industries to set emissions targets, although their achievement for long-range flights is subject to an ongoing debate. Among promising candidates are hydrogen and sustainable aviation fuels such as biofuel. To provide a meaningful ecological and economic assessment, an environmental life cycle assessment method supplemented by a direct operating cost analysis has been developed and is described in this paper. A wide-body transport aircraft (A330 class) serves as a reference design for developing conceptual aircraft designs with a planned entry-into-service in 2040 powered by liquid hydrogen or drop-in biofuels (based on algae, produced with oil-rich biomass (BtL) or hydrogenated vegetable oil (HVO) processes). Due to the large demand for assumptions, the ecological and economic assessment results have to be interpreted as benchmarks. The results for long-range aircraft show that based on the current fuel and energy production methods both hydrogen and biofuel as aviation fuel are more harmful (have a higher environmental impact) than conventional aircraft. For hydrogen aircraft, an increase in energy consumption of 2.87% leads to an increased environmental impact of 14.8%. Due to the high energy demand for biofuel production, its environmental impact increases by 548% (BtL) and 238% (HVO). Nevertheless, for a future scenario based on electrolysis as a hydrogen production process and on renewable energy to generate electricity, both hydrogen and biofuel-powered aircraft are less harmful when compared to the reference aircraft. The environmental impact reduces by 59.5% (hydrogen), 35.8% (BtL), and 112% (HVO). However, the introduction of the new propellants involves a high direct operating cost penalty of 10.8% for hydrogen and 108% for both biofuels.