Definition
What Sustainable Aviation Fuel is — and is not.
Sustainable Aviation Fuel is jet fuel made from non-fossil feedstock. Chemically it is the same class of hydrocarbon as conventional jet fuel, which is the entire point: it is a drop-in fuel. It goes into the same tanks, the same pipelines, the same wing, and burns in the same engine. No aircraft has to be modified and no airport has to be rebuilt.
SAF is not an alternative fuel in the sense that hydrogen or batteries are. It does not change the aircraft; it changes where the carbon came from. Because the feedstock absorbed carbon while it grew, the lifecycle emissions of a certified pathway can be dramatically lower than those of fossil jet fuel — commonly cited at up to around 80% depending on feedstock, process and supply chain.
Two things make a fuel SAF rather than simply bio-derived. First, the production pathway must be certified under ASTM D7566, the specification for aviation turbine fuel containing synthesised hydrocarbons. Second, the sustainability of the feedstock and the lifecycle emissions must be independently verified — under ICAO's CORSIA framework and schemes such as ISCC CORSIA or RSB.
Blending, not replacement — for now
Under current specification, certified synthetic blending components are blended with conventional jet fuel up to defined limits — 50% for most of the major pathways — and the blend is then re-certified to conventional jet fuel specification for use. Work on fully synthetic aviation fuel continues, but the near-term industry is a blending industry, which is exactly why supply volume is the constraint.
Process
Residue in, certified jet fuel out.
The same five stages apply whichever certified pathway is selected. What changes is the intermediate produced in stage three.
- 01
Collect
Residue is aggregated from farms across the Khandesh belt through long-term procurement arrangements and farmer producer organisations.
- 02
Prepare
Material is dried, sized and densified to a consistent specification so the conversion units run on a stable, storable feed.
- 03
Convert
Prepared biomass is converted into an energy-dense intermediate — syngas or alcohol — using an internationally certified licensed process.
- 04
Synthesise
The intermediate is catalytically built into liquid hydrocarbon chains and upgraded to jet-range specification.
- 05
Certify & lift
Fuel is tested to aviation specification, blended with conventional jet fuel and delivered into the airport supply chain.
Pathways
The certified routes, and where residue fits.
ASTM D7566 certifies pathways individually, each as an annex to the standard. Only some of them can use lignocellulosic agricultural residue as a feedstock — which narrows the field considerably for a project built on cane, cotton, soy and pulse waste.
| Pathway | Annex | Typical feedstock | Blend limit | Fit for this project |
|---|---|---|---|---|
| FT-SPK Gasification & Fischer-Tropsch synthesis | A1 | Lignocellulosic biomass, agricultural and forestry residue, municipal waste | 50% | Strong — designed for solid residue |
| ATJ-SPK Alcohol-to-jet | A5 | Ethanol or isobutanol, including cellulosic ethanol from residue | 50% | Strong — leverages India's ethanol base |
| FT-SPK/A Fischer-Tropsch with aromatics | A4 | As FT-SPK, with aromatic content | 50% | Possible variant of the FT route |
| HEFA-SPK Hydroprocessed esters & fatty acids | A2 | Used cooking oil, tallow, vegetable oils | 50% | Not applicable — different feedstock class |
| CHJ Catalytic hydrothermolysis | A6 | Fats, oils and greases | 50% | Not applicable |
| HFS-SIP Synthesised iso-paraffins from sugars | A3 | Fermentable sugars | 10% | Blend limit too restrictive |
Annexes and blend limits reflect ASTM D7566 as published at the time of writing; the standard is revised periodically and the current revision governs. Final pathway selection for the Chalisgaon project will be made with the technology licensor ahead of the final investment decision.
Feedstock
Residue, not crops.
The project uses material that is already a by-product of food production. No land is converted, no edible crop is diverted, and the indirect land use change debate that surrounds first-generation biofuels does not apply in the same way.
Sugarcane bagasse
The fibrous residue left after cane is crushed — abundant, already aggregated at mill gates.
Sugar mill catchmentCotton stalks
Woody stems left standing after picking, today largely uprooted and burned in the field.
Khandesh cotton beltSoybean husk
Processing residue from one of Maharashtra's largest oilseed crops, available year-round.
Oilseed processingPigeon pea residue
Stalk and pod waste from tur cultivation, collected after the rabi harvest window.
Pulse crop residueWhy aggregation is the real engineering problem
Converting biomass to fuel is well understood. Getting several hundred thousand tonnes of loose, seasonal, low-density material to a plant gate at a stable price and specification is the part that determines whether the asset works.
The project is therefore being built with its supply chain, not after it: defined collection catchments, satellite densification and storage yards, contracted transport, moisture and ash specifications agreed at the point of purchase, and long-term offtake agreements with farmers and farmer producer organisations so that supply is not re-negotiated every season.
Sustainability has to be provable
Under CORSIA, an airline can only claim emissions reductions for fuel whose sustainability has been verified by an approved certification scheme. That verification runs backwards along the entire chain of custody — to the field.
The project's procurement system is being designed to carry that evidence: origin records for every consignment, mass-balance accounting through storage and processing, and third-party audit. The commercial value of the fuel depends on it.
Questions
Frequently asked
Is SAF safe to use in existing aircraft?
How much does SAF reduce emissions?
Which technology will the Chalisgaon plant use?
Does using crop residue harm soil health?
Who buys the fuel?
What stage is the project at?
Further reading
- Reference
Sustainable Aviation Fuel solutions
A technology provider's overview of biomass-to-SAF production routes.
Haffner Energy ↗ - Framework
CORSIA — Carbon Offsetting and Reduction Scheme for International Aviation
The ICAO framework governing eligible fuels and airline emissions claims.
ICAO ↗ - Industry
Sustainable Aviation Fuels
Airline industry position, supply outlook and policy tracking.
IATA ↗
Technology partners
Licensors and EPC contractors, get in touch.
If you license a certified residue-to-jet pathway, build process plants at this scale, or supply critical equipment, we would like to include you in the evaluation.