A 200-liter batch of green methanol-derived e-SAF made at an EU pilot plant in September 2025 could enter three regulatory programs, yet receive three materially different CI values. This is not a hypothetical flaw. It reflects an unresolved methodological split between CORSIA, ReFuelEU, and the US SAF blender tax credit, known to producers and regulators for years.
We examine each framework's system boundaries, electricity grid attribution, and results for green methanol pathways.
Three Frameworks, One Fuel
CORSIA, ReFuelEU, and the US SAF credit under Section 40B of the Inflation Reduction Act pursue the same basic aim: calculate lifecycle CO2-equivalent emissions per unit of fuel energy, compare them with a fossil baseline, and use the reduction for credit or compliance. They differ in system boundaries, counted emissions, and treatment of renewable electricity's carbon content.
None is incorrect. Each embodies policy choices for a particular regulatory setting, market actor, and stage of SAF development. Those choices explain why one fuel can receive different CI scores.
CORSIA's LCAF Methodology
ICAO's CORSIA program requires lifecycle analysis under the CORSIA Eligible Fuels framework and its Default Carbon Intensity values, or through an approved LCA tool. Its fossil fuel comparator is 89.1 gCO2e/MJ. CORSIA eligibility requires at least a 10 percent lifecycle reduction from that baseline.
For electrofuels, CORSIA applies the CORSIA LCAF methodology. Producers must record the electrolysis electricity source. Additionality requires renewable electricity from new capacity not already included in the regional grid average, consistent with the EU's Renewable Fuels of Non-Biological Origin rules.
e-SAF made with regional grid-average electricity may therefore fail CORSIA's additionality test despite a low grid CI. Documented PPAs for new renewable capacity are generally needed for CORSIA credit eligibility.
CORSIA Phase 2 applies to international aviation operators, not fuel producers directly. Airlines receive the credit for offsetting their CORSIA obligation, so e-SAF producers must know their airline counterparties and whether those airlines have a CORSIA documentation structure.
ReFuelEU and the RED III Calculation Method
ReFuelEU Aviation starts SAF blending mandates at 2 percent in 2025 and raises them to 6 percent by 2030, with sub-mandates for electrofuels. CI calculations refer to the EU Renewable Energy Directive (RED III) and delegated acts for Renewable Fuels of Non-Biological Origin.
RED III assigns electricity input a default CI based on the production country's annual average grid emissions factor, unless the producer documents real-time or contracted renewable power meeting specified additionality and temporal correlation criteria. For green hydrogen and e-methanol feedstock, methanol CI carries through from the upstream electricity source.
ReFuelEU differs from CORSIA by using a 94 gCO2e/MJ fossil fuel comparator for aviation fuel. Eligible SAF must reduce CI by 65 percent below it. Renewable-electricity e-SAF can meet this threshold; e-SAF using EU grid-average electricity likely cannot.
As strict RED III implementation progresses, renewable electricity temporal correlation requirements are tightening. Monthly matching of renewable generation to hydrogen production is the current minimum in some scenarios, while hourly matching is the expected direction by 2030. This makes documentation harder for producers whose plants are separate from their renewable power source.
The US SAF Credit and the GREET Model
Under Section 40B of the IRA, SAF receives a blender tax credit of $1.25 per gallon at a 50 percent lifecycle greenhouse gas reduction below the fossil jet fuel baseline, increasing to $1.75 per gallon at a 100 percent or greater reduction. CI is calculated with Argonne National Laboratory's GREET model, specifically its SAF GREET pathway modules.
GREET differs from CORSIA's LCAF and RED III by using US-specific electricity grid emission factors rather than European factors. For a European e-SAF producer selling into the US, this creates a translation problem: one fuel needs documentation under multiple frameworks, with different allocation and electricity accounting rules.
For methanol-to-jet e-SAF, GREET includes a Power-to-Liquid pathway module covering methanol synthesis and MtJ conversion. Its defaults come from published engineering estimates and may miss optimized conditions. Producers with better-than-default efficiency should submit actual process data, since the default CI may understate the achieved reduction.
Where the Frameworks Diverge
All three frameworks recognize that e-SAF made with green electricity can cut CI substantially against fossil Jet-A, potentially by 75 to 90 percent depending on electricity source and production route.
Their differences concern electricity carbon attribution, co-product treatment, and the comparison baseline. Electricity is especially consequential: CORSIA requires additionality records, RED III requires temporal and geographic correlation in certain cases, and GREET uses national or regional grid averages unless actual power-source documentation is chosen.
Thus, one facility making one fuel with identical energy inputs could receive CI scores 15 to 25 gCO2e/MJ apart, depending on the framework and electricity accounting method. For a pathway valued for CI reduction, that difference is material.
Implications for e-SAF Producers
We are not saying any framework is wrong. We are saying their design choices serve different purposes: CORSIA's additionality rule limits double-counting of existing renewables, RED III's temporal correlation checks that renewable power was available during hydrogen production, and GREET's grid averages reflect US electricity procurement.
A single LCA study is rarely enough. Producers seeking CORSIA credits, EU SAF mandates, and US tax credits need framework-specific documentation using actual process data instead of pathway defaults.
For green methanol-derived e-SAF, the PPA structure is often the key variable. A long-term PPA with a new wind or solar facility meets all three frameworks' additionality interpretations. Strict RED III implementation increasingly requires hourly matching through regional certificates; CORSIA does not yet require it but may move toward it by Phase 3.
The Documentation Gap
The main gap is between regulatory requirements and what most small e-SAF producers currently document. CI reduction is achievable under the right conditions. Proving it to three regulatory systems through auditable data trails remains a bottleneck.
Multi-framework LCA documentation requires data infrastructure. That work affects access to available policy incentives: a producer may optimize its process yet leave revenue unclaimed if it cannot document performance to each framework's standard.
Our practical advice to e-SAF partners is to make compliance documentation a parallel engineering project. Design plant data capture, renewable electricity contracts, and third-party verification relationships in from the start rather than adding them after first production.