Today, with air transport accounting for 2-3% of global CO2 emissions, the IATA expects sustainable aviation fuel (SAF) to be the N°1 contributor to decarbonisation of the industry by 2050. Authorized globally since 2011, renewable fuels reduce emissions by 80% compared to traditional kerosene, and aim, ideally, to power aircraft up to 100%. In 2024, SAF represented only 0.53% of all aviation fuel. Blended with conventional fuel using fossil resources, SAF components are made from feedstocks, ie. waste or residue from renewable sources: used cooking oils, fats, vegetable oils, alcohols such as ethanol and iso-butanol, green hydrogen, algae, municipal, agricultural, and forestry waste. In 2023, SAF volume exceeded 600 million litres, twice as much as in 2022, but 2 to 5 times more expensive than conventional fuel. Higher production demands collaboration between governments, industry, and regulators worldwide, though limited availability of land and biowaste is the N°1 challenge. Fluctuating demand for air transport is another factor. The IATA predicted in June that passenger traffic growth, which had been on the rise, will decelerate to 5.8% in 2025 from 10.6% in 2024. SAF technology faces a huge challenge to accelerate.

Among current developments, Neste, a prominent biofuel producer, scaled up its SAF production in 2022, partnering with airlines and fuel suppliers to expand accessibility and reduce costs while exploring emerging raw materials such as acid oil and wastewater-derived grease. Airbus targets at least 30% SAF in its global fuel mix for its own flights by 2030, invites its clients to fuel their new aircraft with SAF, and runs 100% SAF flight tests to explore the impact of SAF emissions on the atmosphere. Shell sees synthetic kerosene as a long-term solution for high-volume SAF production. It combines captured carbon from industry and agriculture (and directly from the air, in future decades) with green hydrogen from water and renewable power. Elsewhere, researchers have converted agricultural and forestry waste into SAF using a new catalytic process which could create a circular economy using waste products rather than crops. Power-to-liquid fuels uses renewable electricity to synthesise hydrocarbons from water and carbon dioxide. Another process to produce SAF from carbon dioxide is Direct Air Capture using hydrogen and a metal catalyst to create a closed-loop carbon cycle. If scaled efficiently, these last two systems could provide aviation with a near-limitless supply of sustainable fuel. Finally, and crucially, wider research is now being joined by expanding SAF facilities worldwide, and governments stepping up their support with tax credits and subsidies. Will 25 years suffice to reach the target?