Sustainability of aviation fuel technologies depends on geography, energy, and feedstock choice: 50-year development scenarios

This work presents a combined geographically-resolved prospective lifecycle modelling and multi-criteria decision analysis of five sustainable aviation fuel (SAF) production technologies using six waste-derived feedstocks across four leading producer nations (US, China, India, Brazil) from 2025 to 2075. 540 pathway-scenarios covering the 50-year evolution of each waste-to-fuel pathway are evaluated under three Shared Socioeconomic Pathways. Here we show that the sustainability of SAF production is highly sensitive to feedstock, conversion technology, geography, and background systems. Grid decarbonisation drives SAF global warming potential (GWP) reductions by 2075, yet electrification triggers significant non-carbon trade-offs. While gasification-Fischer-Tropsch achieves the lowest GWP, 2050 multi-criteria leaders are exclusively hydrothermal liquefaction pathways in the US, Brazil, and China, the latter overtaken in 2075 by sugarcane trash gasification-Fischer-Tropsch and US used cooking oil valorisation. The US mostly demonstrates the lowest environmental impacts and India the highest due to waste disposal practices and paradoxical ‘sustainability’ strategies that prioritise short-term coal use to secure future development targets.