Aviation is hard to electrify because batteries are too heavy for long flights. Sustainable aviation fuel (SAF) is the leading near-term answer: a drop-in kerosene that works in existing engines and pipelines but is made from sustainable carbon, cutting lifecycle CO₂ by up to ~80% versus fossil jet fuel.
Working principle
Several certified pathways exist. HEFA hydrotreats waste fats and oils into paraffinic kerosene — the most mature route. Gas/biomass-to-liquid routes gasify feedstock to syngas (CO + H₂), then use Fischer–Tropsch synthesis over a catalyst to build hydrocarbon chains, which are refined to jet range. The frontier route, Power-to-Liquid (e-fuel), combines captured CO₂ with green hydrogen to synthesise fully synthetic kerosene.
| Pathway | Feedstock | Maturity |
|---|---|---|
| HEFA | Waste oils & fats | Commercial |
| Fischer–Tropsch (BtL/GtL) | Biomass / waste → syngas | Demonstration–early commercial |
| Alcohol-to-Jet | Ethanol / isobutanol | Emerging |
| Power-to-Liquid (e-SAF) | CO₂ + green H₂ | Pilot / scaling |
Key insightSAF's value is being drop-in: no new aircraft or infrastructure needed. The constraints are feedstock availability and cost — especially the energy needed for e-fuels.
Applications
- Blending into commercial jet fuel to meet aviation climate mandates
- E-fuels for routes where biomass feedstock is scarce
- Co-production of renewable diesel and chemicals
References & further reading
- ICAO, “Sustainable Aviation Fuels Guidance and CORSIA framework,” 2023.
- Schmidt et al., “Power-to-Liquids as Renewable Fuel Option for Aviation,” Chemie Ingenieur Technik, 2018.
- Wang et al., “Review of biojet fuel conversion technologies,” Renew. Sustain. Energy Rev., 2019.