The certification timeline problem starts with 18-24 months of documentation. CORSIA Phase 2 began in January 2024, and the ICAO CORSIA Eligible Fuels list now includes electrofuels under the synthetic-fuels pathway for lifecycle carbon intensity at or below 10 gCO2e per MJ. For a methanol-to-jet producer using green hydrogen and CO2 from direct air capture or biomass, listing is theoretically possible. In practice, the documentation barrier is beyond the current preparation of most early-stage producers.
We set out what CORSIA Phase 2 eligibility requires from an e-SAF producer, where documentation bottlenecks occur, and what must be prepared before a certification application has a reasonable chance of success. This is for producer technical and sustainability teams, not airline compliance officers, whose concerns differ.
What Phase 2 Changed for Electrofuel Producers
CORSIA Phase 1 ran from 2021 to 2023 and mainly served as an industry learning period. Its eligible fuels list consisted largely of HEFA and a small number of other established pathways. Electrofuels were not ruled out in principle, but no e-SAF pathway had been listed.
Phase 2 brought revised CORSIA Sustainability Criteria and a revised CORSIA Default Life Cycle Emissions Values document. For the first time, the default values give a quantitative lifecycle carbon intensity range for methanol-to-jet e-fuel made with renewable electricity and CO2 from direct air capture or biogenic sources. The e-fuel pathway's indicative default is below 20 gCO2e per MJ on a lifecycle well-to-wake basis. The certified value for a facility depends on its electricity source, CO2 source, and process energy inputs.
The most important change for producers is access to non-default values. CORSIA permits a facility-specific lifecycle analysis instead of the default, which may be conservative compared with the result from a well-optimized facility using high-quality renewable electricity. A facility-specific LCA can produce a lower certified carbon intensity, useful when discussing airline offtake with counterparties managing CORSIA compliance by carbon intensity per unit.
Core Documentation Requirements
An e-SAF pathway becomes CORSIA eligible through approval under a CORSIA-approved sustainability certification scheme. As of early 2026, ISCC CORSIA and RSB CORSIA include e-fuel pathways in scope. Either scheme requires a third-party audit against sustainability criteria, including carbon intensity and social and environmental safeguards. CORSIA sets these requirements; national authorities retain responsibility for how they interpret and apply them.
The audit requires four main parts of carbon intensity documentation. First, a facility mass and energy balance covering inputs, including electricity, CO2 feedstock, water, and process chemicals, plus outputs such as product streams, waste streams, and exported energy. Second, a lifecycle inventory for each upstream input, including emissions from electricity production, CO2 capture or sourcing, and other significant upstream activities. Third, a documented method for combining these data into a total well-to-wake carbon intensity aligned with the CORSIA LCA methodology framework. Fourth, quality assurance showing that the balance uses actual metered production data rather than modeled estimates.
The fourth requirement is hardest for producers that did not collect data for this purpose. CORSIA-aligned auditors will not accept a mass and energy balance based mainly on process simulation. They require actual metered data for a defined production period, with documented measurement uncertainty.
Electricity Additionality Requirement
For most producers, proving electricity additionality is the most demanding technical part of CORSIA e-SAF certification. CORSIA, like ReFuelEU and the EU Delegated Act on renewable fuels of non-biological origin, requires renewable electricity used for electrolysis to produce green hydrogen to be additional, rather than assigned to the general grid mix. It must be directly attributed to new renewable generation capacity.
CORSIA accepts three ways to demonstrate additionality: on-site renewable energy production; a power purchase agreement with a new renewable generator that meets temporal and geographic correlation criteria; or grid certificates together with evidence of new capacity installation. The third is easiest administratively but receives the closest auditor scrutiny.
For a small producer in Europe, a dedicated PPA with a wind or solar facility is typically the practical route to additionality compliance. It must meet temporal correlation requirements, matching renewable generation to electrolyzer consumption hourly rather than annually. Hourly matching needs more advanced metering and energy management and typically raises the effective renewable electricity cost.
We are not saying hourly matching makes e-SAF uneconomic; we are saying producers whose electricity sourcing was not designed for CORSIA temporal correlation will face substantial renegotiation or restructuring before certification. Doing that afterward is considerably more expensive and time-consuming than designing the sourcing structure correctly at the outset.
The LCA Documentation Gap Most Producers Face
Pilot-mode producers often log process data at the DCS level, but the data is not structured for LCA use. A CORSIA-compatible LCA must be organized by time period, converted to a per-unit-product denominator, and linked to the corresponding production output with documented uncertainty bounds. The analysis is not complex, but reconstructing it from scattered DCS logs requires either a purpose-built data management system or substantial manual effort.
The gap is greatest when the operational history used for the LCA includes multiple catalyst charges or significant process modifications. Every modification affecting the mass and energy balance must record what changed and when, so the auditor can assess which production periods represent the current operating state.
Since early pilot operations, our sustainability team has designed our data collection architecture around CORSIA documentation requirements to avoid reconstruction. Retrospective work is costly. Starting correctly requires an added discipline of data labeling and aggregation, manageable when built into the operating workflow rather than added as a separate reporting task.
A Practical CORSIA Certification Sequence
For planned CORSIA Phase 2 eligibility, we would sequence the work this way. First, structure electricity sourcing for additionality before scaled production starts. Second, meter every mass and energy balance input from the first day of production, with the LCA reporting structure defined in advance. Third, choose a CORSIA-approved sustainability certification scheme and enter its pre-certification advisory process early, before a formal application. This engagement finds documentation gaps before the audit, when fixing them costs substantially less.
Well-prepared producers can achieve certification. The timeline is long but reasonable: under ISCC CORSIA, a well-prepared application typically takes 6 to 12 months from initial engagement to certificate issuance when there are no major documentation gaps. A planned commercial offtake date should therefore be preceded by starting documentation preparation 12 months earlier.