Sustainable Aviation Fuels

HomeLearnFuel TypesSustainable Aviation Fuels

Most commercial aircraft use aviation turbine fuel, a kerosene-range fuel commonly known as Jet A or Jet A-1. Sustainable aviation fuel (SAF) is a low carbon liquid fuel (LCLF) alternative for conventional jet fuel. A synthetic blending component made from renewable feedstocks is blended with conventional jet fuel to make SAF, which can be used in existing aircraft and airport fuelling infrastructure.

Explore
Fischer-Tropsch (FT) Fats and oils (HEFA) Sugars (SIP) Alcohol-to-jet (ATJ) Hydrothermolysis (CHJ) Algae oils (HC-HEFA) Co-processing

Sustainable aviation fuel

Also known as

SAF
SATF
SSJF
FSJF

SAF is not a single fuel but a blend. A synthetic blending component made from renewable or waste feedstocks is mixed with conventional jet fuel up to an approved limit, commonly 50%. The component must come from a pathway approved under ASTM D7566, and the finished blend is certified against the standard jet fuel specification, so airlines and airports handle it as ordinary Jet A-1.

Key standards and certifications
Technical

Defence Standard 91-091

for Jet A-1

UK MoD specification widely adopted for international Jet A-1 supply. Def Stan 91-091 is the only specification that fuels in Australia are refined, imported and procured against.

ASTM D7566

Specification for Aviation Turbine Fuel Containing Synthesized Hydrocarbons

US standard for jet fuel containing synthesized hydrocarbons. Each approved production pathway is defined as a numbered annex (A1-A8). The reference SAF blending specification globally.

ASTM D4054

Standard Practice for Evaluation of New Aviation Turbine Fuels and Fuel Additives

US standard practice for qualifying new SAF production pathways for inclusion in D7566. New pathways pursue qualification through this multi-step evaluation framework before approval as a D7566 annex.

ASTM D1655

Specification for Aviation Turbine Fuels

US standard for conventional aviation turbine fuel (Jet A, Jet A-1). Once blended with conventional jet fuel under ASTM D7566, the finished fuel meets ASTM D1655.

Certifications and schemes

Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA)

International Civil Aviation Organization (ICAO)

International framework governing emissions from international aviation. SAF that meets CORSIA Eligible Fuels sustainability criteria can be credited against airline emissions obligations under the scheme.

International Sustainability and Carbon Certification (ISCC)

ISCC System GmbH

Voluntary, globally recognised certification covering biofuel sustainability, GHG emissions and chain of custody. ISCC CORSIA is approved for SAF; ISCC EU enables product sale into European aviation markets.

Roundtable on Sustainable Biomaterials (RSB)

Global certification standard for sustainable biomaterials, biofuels and biomass production.

ICAO-approved voluntary certification scheme for SAF claiming CORSIA Eligible Fuel status. Certifies sustainability of feedstocks, production processes and chain of custody.

Guarantee of Origin scheme

Australian Government (Clean Energy Regulator)

Voluntary Australian scheme that provides a transparent, publicly accessible record of the emissions associated with the production of key commodities. The scheme is being expanded to cover low carbon liquid fuels.

Production pathways

Each pathway produces a synthetic blending component that is approved, or being qualified, for use in jet fuel.

Standards and approvals
ASTM D7566 Annex A1 and Annex A4
Maximum blend
50% with conventional jet fuel
Main feedstocks
Lignocellulosic biomass (forestry and agricultural residues, energy crops), municipal solid waste

FT-SPK from biomass or waste gasification (biomass-to-liquid, BtL)

Biomass or waste
→
Gasification
→
SyngasCO + Hâ‚‚
→
Fischer-Tropsch synthesis
→
Distillation to jet

This pathway also produces FT diesel and FT naphtha co-products in the final fractionation step

Variant of this pathway

Fischer-Tropsch synthetic kerosene with aromatics (FT-SKA)

Standards and approvals
ASTM D7566 Annex A4
Maximum blend
50% with conventional jet fuel
Main feedstocks
Lignocellulosic biomass (forestry and agricultural residues, energy crops), municipal solid waste

How this variant differs Adds an alkylation step to incorporate aromatic compounds from non-petroleum sources. The aromatics help maintain elastomer seal swell in older aircraft.

What is added to the FT-SKA pathway

Paraffins
→
Light aromaticse.g. benzene
→
Alkylation
→
Paraffin + aromatic blend
→
Distillation to kerosene with aromatics

This pathway also produces FT diesel and FT naphtha co-products in the final fractionation step

Standards and approvals
ASTM D7566 Annex A2
Maximum blend
50% with conventional jet fuel
Main feedstocks
Used cooking oil, tallow, vegetable oils, other waste oils and fats

HEFA-SPK from oils and fat

Oils and fatsUCO, tallow, vegetable oils
→
Pretreatment
→
Hydroprocessingwith Hâ‚‚
→
Isomerisation and cracking
→
Distillation to jet-range hydrocarbons

This pathway also produces renewable diesel and naphtha co-products in the final fractionation step

Standards and approvals
ASTM D7566 Annex A3
Maximum blend
10% with conventional jet fuel
Main feedstocks
Sugar crops (sugarcane, sugar beet) and other fermentable sugars

SIP from fermented sugars

Sugar feedstockcane juice/molasses
→
Fermentationengineered yeast
→
Farnesene
→
Purification
→
Hydrogenation to farnesane
Standards and approvals
ASTM D7566 Annex A5
Maximum blend
50% with conventional jet fuel
Main feedstocks
Sugar and starch crops (sugarcane, wheat, sorghum, molasses); lignocellulosic biomass via cellulosic ethanol; methanol produced from biomass, biogas, or captured carbon dioxide and renewable hydrogen

ATJ-SPK from sugar and starch crops

Sugar/starch crop
→
Fermentation
→
Ethanol or isobutanol
→
Dehydration + oligomerisation to olefins
→
Hydrogenation + distillation

This pathway also produces a renewable diesel co-product in the final fractionation step

ATJ-SPK from lignocellulosic biomass (cellulosic ethanol route)

Lignocellulosic biomass
→
Pretreatment + enzymatic hydrolysis
→
Cellulosic ethanol
→
Dehydration + oligomerisation
→
Hydrogenation + distillation

This pathway also produces a renewable diesel co-product in the final fractionation step

ATJ-SPK from methanol (methanol-to-jet route)

Biomass, biogas or captured COâ‚‚ + renewable hydrogen
→
Methanol synthesis
→
Methanol
→
Dehydration + oligomerisation to olefins
→
Hydrogenation + distillation

This pathway also produces naphtha and diesel-range co-products in the final fractionation step

Variant of this pathway

Alcohol-to-jet synthetic kerosene with aromatics (ATJ-SKA)

Standards and approvals
ASTM D7566 Annex A8
Maximum blend
50% with conventional jet fuel
Main feedstocks
Same as ATJ-SPK: sugar and starch crops, lignocellulosic biomass via ethanol or isobutanol

How this variant differs Adds an aromatisation step that converts part of the olefin intermediates directly into aromatic compounds, in contrast to FT-SKA, which alkylates externally sourced benzene

What is added to the ATJ-SKA pathway

Ethanol or isobutanol
→
Dehydration to olefins
→
Olefins
→
Aromatisation of part of the olefin stream
→
Aromatics + remaining olefins
→
Hydrogenation + distillation

Like ATJ-SPK, this pathway produces a renewable diesel co-product

Standards and approvals
ASTM D7566 Annex A6
Maximum blend
50% with conventional jet fuel
Main feedstocks
Triglyceride-rich oils: soybean, jatropha, camelina, tung oil; waste fats and greases

CHJ-SPK from triglyceride feedstocks

Triglyceride oil/fat
→
Catalytic hydrothermolysis
→
Hydrothermolysis products
→
Hydrotreating
→
Distillation to jet

This pathway also produces renewable diesel and naphtha co-products in the final fractionation step

Standards and approvals
ASTM D7566 Annex A7
Maximum blend
10% with conventional jet fuel
Main feedstocks
Hydrocarbons and lipids from algae (notably the algal species Botryococcus braunii)

HC-HEFA-SPK from algal hydrocarbons and lipids

Algal biomass
→
Hydrocarbon/lipid extraction
→
Algal hydrocarbons + lipids
→
Hydroprocessing
→
Distillation to jet
Standards and approvals
Def Stan 91-091
Maximum blend
  • Fats, oils and greases (FOG) co-hydrotreating: up to 5% v/v input / up to 5% in the finished fuel
  • FOG co-hydrocracking: up to 30% input / up to 15% in the finished fuel
  • Fischer-Tropsch hydrocarbon co-processing: up to 5% v/v input / up to 5% in the finished fuel
  • Hydroprocessed lipid-derived hydrocarbon co-processing: up to 24% v/v input / up to 10% in the finished fuel
Main feedstocks
Used cooking oil, tallow, vegetable oils; certain Fischer-Tropsch hydrocarbon intermediates; hydroprocessed lipid-derived hydrocarbons

Co-processing of fats, oils and greases (FOG) in refinery hydrotreaters

Renewable feedstock + petroleum
→
Refinery hydrotreaterco-processing
→
Hydrotreated stream
→
Distillation
→
Jet + diesel + other cuts

Co-processing produces renewable diesel, petrol-range cuts and other refinery products alongside the SAF fraction. This is by design: the refinery makes its full slate of fuels in parallel.

Co-processing of Fischer-Tropsch hydrocarbons in refineries

FT hydrocarbons + petroleum
→
Refinery hydrotreaterco-processing
→
Hydrotreated stream
→
Distillation
→
Jet + diesel + other cuts

Same co-product profile as the FOG route – multiple refinery cuts produced in parallel

Co-processing of HEFA in refineries

HEFA-derived hydrocarbonspre-hydroprocessed from fats, oils and greases, + petroleum
→
Refinery hydrotreaterco-processing
→
Co-processed hydrocarbon stream
→
Distillation
→
Jet + diesel + other cuts

Some refineries co-process pre-hydroprocessed HEFA hydrocarbons in their fluid catalytic cracking (FCC) units instead of hydrotreaters, producing a different product distribution but with the same co-product slate.

Keep exploring
Aviation Conversion and upgrading Fuel certification

Resources

A selection from the library related to this page.

    • Report
    • 2025

    Opportunities and Priorities for a Low Carbon Liquid Fuel Industry in Australia
    Commonwealth Scientific and Industrial Research Organisation (CSIRO), prepared in partnership with the Australian Government
    CSIRO report, prepared in partnership with the Australian Government, outlining opportunities for a low carbon liquid fuel industry in Australia and identifying priorities to progress projects from development through to commercial scale.
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    • Policy & program
    • 2024

    Aviation White Paper – Towards 2050
    Australian Government, Department of Infrastructure, Transport, Regional Development, Communications, Sport and the Arts (DITRDCSA)
    Australian Government Aviation White Paper setting out policy directions for the aviation sector to 2050, including actions and settings relevant to sustainable aviation fuel market development.
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    • Policy & program
    • 2025

    Cleaner Fuels Program: Powering low carbon liquid fuel production in Australia
    Australian Government, Department of Infrastructure, Transport, Regional Development, Communications, Sport and the Arts (DITRDCSA)
    Australian Government consultation and program page outlining the Cleaner Fuels Program and its policy design process.
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    • Data & statistics
    • 2026

    Fuel Qualifications (CAAFI)
    Commercial Aviation Alternative Fuels Initiative (CAAFI)
    CAAFI reference page tracking the qualification status of sustainable aviation fuel pathways under ASTM D4054 and ASTM D7566, covering approved annexes with their year of certification, pathways under evaluation and emerging conversion processes.
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    • Technical & scientific report
    • 2024

    Progress in Commercialization of Biojet/Sustainable Aviation Fuels (SAF): Technologies and policies
    International Energy Agency Bioenergy Technology Collaboration Programme (IEA Bioenergy) Task 39
    IEA Bioenergy Task 39 report on SAF technologies, commercialisation progress and policy settings.
    Read more
    • Technical & scientific report
    • 2024

    Sustainable Aviation Fuel State of Play: One year on from the Australian SAF Roadmap
    Commonwealth Scientific and Industrial Research Organisation (CSIRO) and Boeing
    CSIRO-Boeing report summarising the 2024 state of play for sustainable aviation fuel in Australia, including feedstock potential, project activity and priority actions to progress projects and secure offtake.
    Read more
    • Report
    • 2024

    SAF Handbook
    International Air Transport Association (IATA)
    IATA handbook for airlines on sustainable aviation fuel, covering technical, operational, certification and supply chain considerations for SAF deployment.
    Read more
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