SAF Pathways Reference

ASTM D7566-approved sustainable aviation fuel pathways — HEFA, ATJ, FT-SPK, CHJ, SIP — with feedstocks, blend limits, and CI scores.

SAF Pathways

Sustainable Aviation Fuel (SAF) Pathway Comparison · ASTM D7566-approved Annex pathways, feedstocks, CI, TRL, yield — 2024 IEA + ICAO CORSIA data

Pathway	ASTM Annex	Max Blend %	Feedstock	Typical CI (gCO2e/MJ)	Fossil Jet-A CI	TRL	Commercial?	Yield (gal SAF / ton feed)	Notes
HEFA (Fischer-Tropsch if FT-SPK)	A1 (FT-SPK), A2 (HEFA-SPK)	50%	Oils, fats, greases (UCO, tallow, soybean)	20-40	89	9	Yes (Neste, World Energy, Montana Ren.)	260 (UCO)	Commercial since 2011; Infinium-friendly
ATJ (Alcohol-to-Jet)	A5	50%	Ethanol, isobutanol (corn, cellulosic)	30-55	89	7-8	Yes (LanzaJet, Gevo)	170	Gevo Net-Zero 1 project; cellulosic ethanol drops CI
FT-SPK/FT-SPK/A (syngas route)	A1, A4	50%	Biomass/MSW/CO2+H2	-5 to +15	89	7-8	Pilot/commercial (Fulcrum, Velocys)	85 gal/ton biomass	Requires gasifier + FT loop + hydrocracker
HFS-SIP (synthesized iso-paraffins)	A3	10%	Sugars to farnesene	40-60	89	8	Yes (Amyris/Total)	60	Limited blend pct; niche
CHJ (Catalytic Hydrothermolysis Jet)	A6	50%	Triglycerides	35-50	89	7	Pilot (ARA)	230	Single-step vs HEFA multi-step
HC-HEFA (Algal)	A7	10%	Microalgal oil	30-50	89	5	R&D (IHI)	150	Algae still high cost; 10% blend cap
Power-to-Liquid (eFuel/RWGS+FT)	Pending (A8 candidate)	50%	CO2 + green H2 + electricity	-10 to +5	89	6-7	Infinium Lake Charles, NORSK	~0.25 gal/kWh	Infinium Reactive CO2 Capture + FT; regulated as Annex A1 eq.
e-SAF (Methanol-to-Jet)	Under ASTM review	-	MeOH from CO2/H2	0 to +10	89	5-6	Pilot	-	Still early; Honeywell/Topsoe process packages

CI Benchmarks

CI (Carbon Intensity) Benchmarks — gCO2e/MJ · CORSIA Default Values (2023) / CARB-approved LCA

Pathway / Feedstock	Default CI	Reduction vs Fossil Jet-A (89)	Notes
HEFA — UCO	13.9	84%	Best-in-class; Neste MY SAF
HEFA — Tallow	22.5	75%	Animal fat; by-product credit
HEFA — Soybean oil	54.0	39%	LUC penalty; US soy has iLUC in CORSIA
HEFA — Palm fatty acid distillate	20.0	78%	Sustainability criteria apply
ATJ — Corn grain ethanol	65.7	26%	Marginal reduction; no cellulosic path
ATJ — Sugarcane ethanol	23.8	73%	Brazil advantage
ATJ — Miscanthus cellulosic	11.0	88%	Feedstock availability limited
FT — MSW	5.2	94%	Avoided-emissions credit from landfill diversion
FT — Biomass (wood)	8.3	91%	Forestry residue based
PtL — Wind + DAC	1.2	99%	With 100% renewable power
PtL — Grid + CO2 point source	44.0	51%	Only valid if grid decarbonized

References

Source: SAF_Pathways_Reference_v1.xlsx

© 2026 Inflection Point Engineering, LLC. All rights reserved. The content of this page — including calculation methods, reference data, written analysis, interactive tools, and source code — is the intellectual property of Inflection Point Engineering, LLC and is protected under applicable copyright, trademark, and trade secret laws. Unauthorized reproduction, redistribution, modification, or derivative use in whole or in part is prohibited without prior written consent.

Disclaimer. This material is provided for informational and educational purposes only and does not constitute professional engineering advice. Calculations, reference data, and methodologies are based on published standards and accepted engineering practice but are not a substitute for engineering judgment, site-specific analysis, or review by a licensed Professional Engineer. Inflection Point Engineering, LLC makes no warranties, express or implied, regarding the accuracy, completeness, or fitness for a particular purpose of any content presented here, and shall not be liable for any direct, indirect, incidental, or consequential damages arising from its use. Users assume all risk associated with applying this content to real-world design, operations, or decisions.