SAF, sustainable aviation fuel: what is the biofuel produced from municipal waste

Researchers from Tsinghua University, in collaboration with theHarvard China Project on Energy, Economy and Environmenthave demonstrated the technical feasibility of converting the solid waste urban (MSW), traditionally destined for landfill or incineration, in Sustainable Aviation Fuel (SAF), a biofuel certified for commercial aviation. This approach would drastically reduce the climate impact of the aeronautical sector, accelerating the achievement of the Net Zero Emissions objective, and at the same time support cities in managing the growing volumes of MSW.

Commercial aviation contributes approximately 2.5% to global anthropogenic emissions of carbon dioxide (CO₂), with demand for passenger flights expected in doubling by 2040. Unlike other sectors in progressive transition towards electrification, aeronautics presents persistent challenges to achieve carbon neutrality: long routes, complex infrastructures and high energy density heat engines prevent significant reductions in greenhouse gases (GHG), responsible for global warming. In such a scenario, the SAF is configured as a primary lever of decarbonisation on an industrial scale.

What is SAF and how is it produced

In the initial phase of the process, mixed municipal solid waste, consisting mainly of organic waste, paper, cardboard and plastics, is subjected to differentiated qualitative sorting. Subsequently, the selected flow undergoes a thermo-chemical gasification at high temperature, producing syngasa gaseous mixture rich in hydrogen (H₂) and carbon monoxide (CO). The syngas is first purified from contaminants, tar and impurities through integrated cleaning and fine filtering processes, and then introduced into a reactor Fischer-Tropschwhere the catalytic synthesis of long-chain linear hydrocarbons (paraffins) occurs. Finally, the raw liquids obtained undergo an “upgrading”, through hydroisomerization and selective cracking, to produce a fraction of kerosene complies with industry specifications for certified aviation fuels. The SAF – Sustainable Aviation Fuel – resulting is a biofuel fully compatible with commercial aviation turbofan and turbodrop engines, reduces greenhouse gas emissions80-90% on the complete life cycle compared to conventional jet fuel and does not require adaptations to existing airport refueling infrastructures.

The potential of Sustainable Aviation Fuel

Although the Sustainable Aviation Fuel currently represents less than1% of global jet fuel consumption, limited by high production costs (3-5 times higher than fossil fuels) and limited available industrial capacity, its scale potential is significant, supported by decarbonisation policies and technological advances. In future perspective, municipal solid waste could generate globally approximately 50 million tons of SAF, equivalent to 62 billion litres nod. This volume would reduce CO emissions₂ global commercial aviation life cycle equivalents of approximately 16%. By integrating green hydrogen, produced via electrolysis powered by renewable sources, into the Fischer-Tropsch phase and optimizing the energy efficiency of the plants, SAF’s production capacity could reach 80 million tons annually, covering the 28% of the world’s jet fuel needs and avoiding up to 270 million tons of carbon dioxide equivalent over the life cycle.

This return would guarantee compliance with the obligations of ReFuelEU AviationEU regulation 2023/2405 which requires aviation fuel suppliers to supply European Union airports with mixtures containing at least the 3% of SAF from 2026with a gradual scale up to 70% by 2050. Furthermore, to comply with the LANE (Carbon Offsetting and Reduction Scheme for International Aviation), the program approved byICAO (International Civil Aviation Organization) to stabilize CO emissions₂ of international flights at 2020 levels by requesting airlines compensation beyond this threshold, the growing use of SAF would drastically reduce compulsory purchases of certified carbon credits, generating significant economic-financial benefits for scheduled operators.