The whole course, in one place.

Almost every conversation about aviation and climate arrives at the same place within a few minutes. Someone asks what sustainable aviation fuel actually is, and whether it is a real fuel or a piece of accounting.

It is a real fuel. It goes into a real aircraft and burns in a real engine. The part that takes explaining is where the saving happens.

What is SAF?

SAF stands for sustainable aviation fuel, and the two are used interchangeably once the acronym has been introduced. It is jet fuel made from sustainable feedstocks rather than fossil crude. Most of what reaches the market today starts as used cooking oil, waste fats and tallow, or technical corn oil recovered during ethanol production.

The chemistry is deliberately unremarkable. SAF is a drop-in fuel, which means it meets the same technical standard as conventional jet fuel, ASTM D1655, and works in existing aircraft, existing engines and existing airport infrastructure. Nothing needs modifying. In practice it is blended with fossil jet fuel rather than used neat, and the blend is what goes into the wing.

One distinction is worth making from the start. A fuel made from something other than crude oil is an alternative fuel, and alternative does not mean sustainable: coal can be converted to jet fuel, and the result is an alternative fuel with a worse carbon footprint than the fossil kerosene it replaces. Sustainability is a separate test, applied afterwards, by someone independent.

Why is it called sustainable if it still burns?

Because the saving is counted across the fuel’s whole life, not at the point of combustion.

Burning SAF still releases carbon. What changes is where that carbon came from. Fossil jet fuel releases carbon that has been locked in geological storage for millions of years, adding it to the atmosphere for the first time. SAF releases carbon that was in the atmosphere recently, taken up by a crop or embodied in a waste stream that already existed. Set the two against each other across production, transport and combustion, and the lifecycle total is lower.

That is why every honest SAF figure is a lifecycle figure with a stated baseline. In our May 2026 transaction with Delta Air Lines, the reduction was calculated against a fossil baseline and verified before anyone claimed it. A number without a baseline is not a claim, it is an adjective.

Does calling something SAF guarantee a large reduction?

No, and this is the most useful thing on this page.

ICAO’s rule for CORSIA eligible fuel is that it “will achieve net greenhouse gas emissions reductions of at least 10% compared to the baseline life cycle emissions values for aviation fuel on a life cycle basis”. Ten per cent is the floor, not the expectation.

Work through what that permits. Take a fuel with a 50% lower lifecycle footprint, blend it into fossil kerosene at a modest percentage, and the resulting blend can still clear the bar and still be described as SAF. Nobody has broken a rule. The word simply covers a wide range, and on its own it tells a buyer very little.

So “we bought SAF” is the beginning of a conversation rather than the end of one. The questions that follow are what the actual lifecycle reduction was, against which baseline, and which scheme verified it. A supplier who answers those in one breath is selling something different from a supplier who repeats the acronym.

Who decides whether a batch qualifies?

A certification scheme, and not the company selling the fuel.

Fuel enters the system only once a recognised scheme has assessed the feedstock, the production pathway and the chain of custody behind it. The schemes set the sustainability criteria, audit against them, and withdraw certification when they are not met. Future Energy Global is certified by both RSB and ISCC as a trader, and audited externally by SCS Global Services.

This matters more than any adjective a marketer can attach. “Sustainable” is a conclusion a scheme reaches after it has seen the evidence, not a word a supplier awards itself.

Why can’t I just buy it at my airport?

Because supply is concentrated near the small number of plants that produce it, and most airports have none.

That is the practical problem the industry is built around at the moment. Production is growing but it is not evenly distributed, and an airline flying from an airport with no SAF cannot buy what is not there. It is also why Book and Claim exists: it separates the certified environmental attributes from the physical fuel, so the fuel is used where it makes sense and the verified reduction is retired to whoever funded it.

What does this change about what you can claim?

Everything, and it comes down to evidence.

A certified batch comes with a record: where the feedstock came from, how the fuel was made, what the lifecycle reduction was, and who ended up owning it. That record is what survives an audit. When someone asks where your reduction came from, the answer should be a document rather than a reassurance.

The gap efficiency can’t close

Aviation produces roughly 2 to 2.5% of global CO₂, and that share has stayed broadly flat for decades. Two trends cancel each other out: aircraft keep getting more efficient, and the world keeps flying more. Between 2009 and 2019, aviation’s CO₂ grew 44% despite the efficiency gains. Efficiency is a percentage. Growth is a multiplier.

For medium and long-haul flying, no alternative to a liquid drop-in fuel is expected for at least 15 years, and an aircraft delivered today will still be flying in the 2050s. That is why every serious industry roadmap lands in the same place. Sustainable aviation fuel (SAF) accounts for around two-thirds of the reductions aviation needs by 2050.

How little there is, and where it is

SAF is under 1% of global jet fuel today. To meet 2050 demand, production needs to scale more than 400-fold.

The little that exists is concentrated. SAF is made where feedstock and refining capacity are, in a handful of regions, and supply at most airports is thin or absent. It is a drop-in fuel, meeting the same technical standards as conventional jet fuel and running in existing aircraft, so the barrier is availability rather than compatibility.

The buyer in the wrong place

An airline in Auckland wants to fly on SAF. The fuel exists, in Montana. A company in Dublin with a business travel target meets the same wall: the fuel is real, and it is on the wrong side of the world. Those places are illustrative, but the geography they describe is the market’s daily reality.

Why shipping it is the wrong answer

Physically moving SAF to the buyer is slow and expensive, and it burns fuel along the way, eating into the very benefit being bought. The producer loses too. A refinery can only sell to the airports its trucks and pipelines actually reach, so good production in the wrong place struggles to find its buyer.

ICAO’s own guidance names the answer: separating the claim from the fuel brings logistical efficiency, and it opens the global market to producers wherever they are.

The idea that unlocks it

Renewable electricity solved this problem years ago. Nobody can trace an electron from a wind turbine to their socket, so the market tracks verified certificates instead, with strict rules so each one is counted once. Book and Claim brings the same discipline to fuel. The fuel is used where it makes sense. What travels to you is the verified environmental attribute.

The next lesson walks through exactly how that settlement works, step by step. For the shorter version, start with what Book and Claim is.

It already works

On 19 May 2026, ITOCHU Corporation supplied physical SAF to an airline at Tokyo Narita Airport and provided the environmental attributes of that fuel to Future Energy Global, for use by our airline and corporate clients. The transaction was registered on the Assure SAF Registry.

The aircraft burned the fuel in Tokyo. The verified claim can be reported wherever a buyer has a target. That is the whole point.

Every buyer arrives at this question, usually about four minutes in. If the fuel is sustainable, what is it made of, and is something else going without so a plane can fly?

It is a fair question, and the honest answer has two halves.

What is sustainable aviation fuel made from?

Most of the fuel reaching the market today starts as something that already exists for another reason. Used cooking oil, collected from restaurants and food manufacturing. Tallow, a by-product of meat processing. Corn oil recovered during ethanol production, which the industry calls Technical Corn Oil or Distillers Corn Oil.

None of those were grown to make fuel. They are the residue of a process that was going to happen anyway. For most of them the alternative destination is a lower-value use, or landfill.

Then there is the second half. Some sustainable fuel does come from crops grown for the purpose, including camelina, canola and soy. That is a real part of the market and pretending otherwise would not survive a serious conversation.

Does it take food off the table?

Sometimes the question is really about land. A residue does not compete for a field, because the field was already in use. A purpose-grown crop can compete, and whether it does depends on where it was grown, what it displaced, and how the land was managed.

This is precisely why the eligibility rules exist, and why they are not written by the people selling the fuel. The trade-offs between feedstocks, and where the next ones come from, are the subject of Out of the Fryer, the report we published with PA Consulting.

Who decides what counts as eligible?

A certification scheme does. Fuel enters the system only when a recognised scheme has assessed the feedstock, the production pathway and the chain of custody behind it. Future Energy Global is certified by both RSB and ISCC, and audited externally by SCS Global Services.

That matters more than any adjective a marketer can attach. “Sustainable” is a conclusion a scheme reaches once it has seen the evidence. A supplier does not get to award it to itself.

What we supply

Most of what we supply is used cooking oil or tallow. We can source technical corn oil as well, and the transaction below is one of those. It is the example we show because every step of it is documented, from the field to the retirement statement.

What it looks like in a real transaction

In May 2026 we settled a transaction with Delta Air Lines. It was built on Technical Corn Oil, a by-product of corn grown by farming communities across Minnesota. Montana Renewables refined it into sustainable aviation fuel and the fuel was uplifted locally. Delta claimed the Scope 1 reduction against flights from its Minneapolis hub. We claimed the Scope 3 reduction against our own employees’ travel.

One batch of fuel. Two distinct reductions, each verified and counted only once.

Why this changes what you can claim

A certificate is only as good as the evidence behind the molecule. If nobody can say where the feedstock came from, the claim rests on trust rather than record. Trust is the thing that fails under audit.

We can follow the fuel back to its source, whether that source is a fryer, a rendering plant or a field. When someone asks where your reduction came from, the answer should be a document, not an assurance.

The two words get used as though they were the same thing, including by people who should know better. They are not, and the gap between them is where a claim either holds up or falls over.

Here is the short version. Most sustainable aviation fuel in the market today is a biofuel. Very little biofuel is sustainable aviation fuel. And some SAF is not a biofuel at all.

Is sustainable aviation fuel a biofuel?

Usually, yes. The dominant production route today is HEFA, which stands for Hydroprocessed Esters and Fatty Acids, and it converts used cooking oil, animal fats, tallow and technical corn oil into jet fuel. All of that is biomass, so the resulting fuel is a biofuel in the ordinary sense of the word.

So if someone calls SAF a biofuel, they are usually describing it accurately. The trouble starts when the sentence runs the other way.

Why isn’t all biofuel sustainable aviation fuel?

Two reasons, and they are worth separating.

The first is simply what the fuel is for. Biofuel is a huge category that includes road diesel, ethanol blended into petrol, marine fuel and heating fuel. Only a small part of it is refined to jet specification, and jet specification is unforgiving because the fuel has to behave identically to fossil kerosene at altitude.

The second reason is the one that matters commercially. “Biofuel” describes where a fuel came from, and says nothing at all about whether it was produced responsibly. A fuel can be entirely biomass-derived and still be tied to land use you would not want your name against. Certification is what closes that gap: a recognised scheme assesses the feedstock, the production pathway and the chain of custody, and only then does a batch earn a verified sustainability claim.

That is the whole distinction. Biofuel is a description of origin. Sustainable aviation fuel is a description of origin that somebody independent has checked.

Is there SAF that isn’t a biofuel?

Yes, and it is the clearest way to see why the words are not interchangeable.

e-SAF, also called power-to-liquid, is made from renewable electricity, water and captured carbon dioxide. There is no biomass anywhere in it. It is unambiguously sustainable aviation fuel and unambiguously not a biofuel. Electricity is the dominant cost, so it depends on cheap renewable power and it is early, but it exists and it breaks the equivalence.

The reverse case is worth knowing too. Lower Carbon Aviation Fuel, or LCAF, is a fossil aviation fuel that meets the sustainability criteria set out under CORSIA. It is neither a biofuel nor a sustainable aviation fuel, despite how close the names sit.

Does the distinction matter for what I can claim?

It decides it.

A reduction claim rests on the certificate behind the batch, and certificates are issued against a scheme’s criteria rather than against a feedstock category. “We bought biofuel” is a purchasing statement. “We retired the certified environmental attributes of a batch audited under RSB or ISCC, and no one else can claim them” is a position you can defend in front of an auditor.

Both descriptions appear in our own certification, which is a useful illustration. Our RSB certificate covers us as a trader of SAF and of maritime biofuels: two different words on one certificate, because they are two different things.

Which word should we use?

Use the one that is true of the fuel in front of you.

For aviation, say sustainable aviation fuel, or SAF once you have glossed it, because that is what the certificate says. For shipping and heavy road freight, biofuel is often the accurate term and there is no reason to avoid it. What does not work is treating them as synonyms, because the moment they become interchangeable in your copy, the certification that separates them stops doing any work.

One batch becomes two things

At the blending point, a batch of certified sustainable aviation fuel (SAF) splits into two things. The physical fuel stays local: it is uplifted at a nearby airport and sold without its sustainability characteristics. The environmental attribute is registered separately, transferred to one owner, and retired once.

That split is not a loophole. It is a recognised chain of custody model, one of three defined in international practice alongside physical segregation and mass balance, and it runs on rules strict enough to survive an audit. Here is the settlement, step by step.

Step 1: certified fuel is made and delivered

Only certified fuel can enter the system. Under the RSB’s rulebook, that means fuel certified by RSB itself, an EU-recognised voluntary scheme, or a scheme recognised under ICAO’s CORSIA. The physical blend is delivered and used near where it was made, and from the moment its attribute is booked, the fuel itself is sold as ordinary fuel, with no green claim attached.

Step 2: the attribute is booked

The supplier registers the batch on a registry as Book and Claim Units. One BCU equals one tonne of neat, certified SAF, and it records the batch’s full sustainability data: feedstock, pathway, lifecycle emissions value, and certification. Registration must happen within 90 days of physical delivery, and no operator can register more certified product than it actually acquired. Only certified chain-of-custody traders can do this; Future Energy Global holds that certification from both RSB and ISCC, audited externally.

Step 3: the attribute changes hands

BCUs are held, transferred, and sold between registry account holders: producers, traders, airlines, and corporate buyers. IATA’s accounting methodology is explicit that Scope 1 claims are not limited by where the fuel was uplifted. Distance is not a defect in this market. It is the design.

Step 4: the claim is retired

Retirement is the moment a claim becomes real. The registry permanently assigns the reduction to named parties, publishes a retirement statement, and takes the unit out of circulation. Retired BCUs cannot be resold. Every unit must be retired within 24 months of registration.

The ordering matters: the airline’s Scope 1 claim is retired or assigned before any corporate Scope 3 claim can be. That sequence proves the fuel was actually used before anyone claims against it. It is how a credible registry is built.

One claim, one owner, counted once.

Who pays, and why it works

The corporate buyer pays for the Scope 3 attribute, and that payment shares the SAF premium that would otherwise fall on the airline alone. The RSB names cost-sharing of the premium as one of Book and Claim’s design goals. Two buyers fund one physical intervention, each receives a verified claim in its own scope, and the producer gets demand it could never have reached locally.

Who claims what, and why that is not double counting, is the whose-emission-is-it lesson. What you actually receive at the end is a retirement statement, and the next lesson reads a real one, field by field.

What a registry is for

A registry is the ledger where Book and Claim happens: where the environmental attributes of sustainable aviation fuel (SAF) are booked, transferred, and retired, under audit. It exists to keep one promise, that each verified reduction is counted once and owned by one party in each scope. Everything else on this page is the machinery behind that promise.

The three ways counting goes wrong

Double counting has three distinct failure modes, and a credible registry designs against each one.

Failure	What it means	What kills it
Double issuance	More than one unit issued for the same reduction	Third-party audited registration, plus registry audit
Double use	The same unit sold or used more than once	Public retirement statements, plus registry audit
Double claiming	Two parties claiming the same reduction in the same scope	Public disclosure of incentives and transparent reporting rules

One thing is deliberately absent from that list. An airline’s Scope 1 claim and a corporate’s Scope 3 claim from the same batch are different accounting entries for different entities. That is the designed outcome, and the next lesson explains why.

What retirement is

A claim only becomes valid for reporting when the unit is retired and the registry issues a retirement statement. Retirement takes the unit permanently out of circulation: it cannot be transferred or resold afterwards. Statements are published, so anyone can check. The RSB’s public retirement table and the CADO SAF Registry’s public redemptions table are both open to read without a login.

You can find us on both. The RSB table lists the retirement group behind the statement below, naming Delta Air Lines Inc. as the Scope 1 party. The CADO table’s record SAFR-3105888104, dated 10 July 2026, names Future Energy Global Limited as the Scope 3 owner of a voluntary redemption. Parties can choose anonymity on these tables; we choose to be named.

The statement is the product. It is what a buyer’s auditor reads.

Reading a real one

Retirement statement RSB-BCU-RS-26-05-0002 was issued by the RSB Book and Claim Registry on 6 May 2026. It is one page. These are its fields, as printed.

Field	Value
BCU ID	RSB-BCU-SAF-26-04-001-0001
Amount	36.213 BCUs, where 1 BCU is 1 tonne of neat certified SAF
CO2eq reduction	114.178 tonnes, on a lifecycle basis
Scope 1, transport service provider	Delta Air Lines Inc.
Scope 3, corporate end-user	Future Energy Capital Limited
Sustainability certification	ISCC CORSIA
Fossil baseline	89.00 gCO2eq/MJ
GHG lifecycle value	17.20 gCO2eq/MJ
GHG emission reduction	80.674%, on a lifecycle basis
Feedstock and pathway	Technical Corn oil, HEFA, blended in the USA
Type of reporting	Voluntary
Eligible incentives used	US RFS (RIN)

Three things worth noticing. The arithmetic is checkable: 1,590,221 MJ of fuel, against an 89.00 baseline, at an 80.674% reduction, gives exactly 114.178 tonnes CO2eq. The incentive field is disclosure working as designed: any national incentive the fuel benefited from must be declared and printed, so nothing is hidden from a buyer’s auditor. And the corporate end-user named is Future Energy Capital Limited, our own legal entity. Before asking any buyer to stand behind a claim, we stood behind one ourselves.

The registries in our world

Our transactions settle on independent registries: the RSB Book and Claim Registry, the Assure SAF Registry, where the ITOCHU transaction at Tokyo Narita was registered, and IATA’s CADO SAF Registry, where we delivered the first transaction, supplying Microsoft. Certification sits underneath them. Future Energy Global is certified as a Book and Claim trader by both RSB and ISCC, issued by SCS Global Services and audited annually.

A retirement statement does not by itself guarantee acceptance under any particular reporting regime, and the RSB says so on the document. What it guarantees is narrower and more valuable: this reduction happened, it belongs to the parties named, and no one else can ever claim it.

Three scopes, in plain terms

The GHG Protocol sorts a company’s emissions into three scopes, and the whole market for sustainable aviation fuel (SAF) runs on the distinction.

Scope 1 is direct: emissions from assets you own or control, which for an airline means the fuel its aircraft burn. Scope 2 covers purchased electricity, heat, and steam. Scope 3 is everything indirect across your value chain, upstream and downstream. Business travel is Scope 3, Category 6; freight you pay others to move sits in Categories 4 and 9.

Scope 2 rarely features in aviation stories, but the frame is incomplete without it.

The same flight, two ledgers

When your team flies, the airline records the flight’s emissions in its Scope 1. Your company records its share of the same flight in its Scope 3. Both entries are real, both are required, and neither cancels the other. One company’s Scope 1 is routinely another company’s Scope 3. That is how the accounting system is built.

Whose reduction is it, then?

When SAF replaces fossil fuel, the reduction lands in both ledgers, so the registry splits the ownership formally. Under the RSB’s rulebook, the airline named on the retirement statement is the exclusive owner of the Scope 1 claim. The corporate end-user named on the statement owns the Scope 3 claim, assigned at retirement, and can use it to compensate for its business travel emissions, capped at its actual footprint in the sector for that year.

IATA’s accounting methodology says the same thing from the other direction: producer, airline, and customer can each make claims against one batch without double claiming, but only one airline can ever make the Scope 1 claim.

Why this is not double counting

Double counting is the same reduction claimed twice in the same scope. The airline’s Scope 1 entry and the corporate’s Scope 3 entry are different accounting entries for different entities, and the registry retires the Scope 1 claim before any Scope 3 claim, proving the fuel was used. One physical intervention, two legitimate claims, each owned once. The registry lesson shows the machinery in detail.

For target setters, the SBTi’s Corporate Net-Zero Standard version 2 states that targets “may be supported by market instruments, including energy attributes and commodity certificates based on different chain-of-custody models (e.g., mass balance, book-and-claim), subject to guardrails”. The standard permits this route, with integrity criteria attached, and it is worth reading those criteria in full. We set out what the SBTi Corporate Net-Zero Standard v2 actually says about Book and Claim in its own piece.

Why this is the commercial engine

The split is what funds the scale-up. Corporate demand for the Scope 3 attribute shares the SAF premium, which is what makes uplift viable for the airline in the first place. Two buyers, one tonne, both reporting genuine progress.

You can see the split in black and white on our own retirement statement from May 2026: Scope 1, Delta Air Lines Inc.; Scope 3, Future Energy Capital Limited. Two names, two scopes, one batch of fuel, counted once each.

If you are the corporate in that sentence, the corporates page is your next step. If you are the airline, yours is here.

CORSIA comes up early in any serious conversation about aviation emissions, usually as an acronym nobody stops to explain. It is worth explaining, because it is the reason certification for sustainable aviation fuel, or SAF, is structured the way it is.

What does CORSIA stand for?

The Carbon Offsetting and Reduction Scheme for International Aviation. It was developed by ICAO, the International Civil Aviation Organization, and approved by the ICAO Council.

The name is a fair description of its origins and a poor description of what most people encounter it for. For anyone buying sustainable fuel voluntarily, the part you meet in practice is the sustainability framework, because it sets the standard certification is audited against.

What does CORSIA actually do for SAF?

Two things, and the second is the one you meet in practice.

It defines the sustainability criteria a fuel has to meet before it counts. And it recognises the independent certification schemes that audit fuel against those criteria, rather than auditing anything itself. ICAO sets the bar; recognised schemes do the checking.

RSB and ISCC are both recognised under CORSIA, which is why their names appear on certificates and registry entries throughout this market. Future Energy Global is certified under ISCC CORSIA and under RSB’s ICAO CORSIA standard, and audited externally by SCS Global Services.

Does a fuel have to be CORSIA certified?

It depends what the fuel is for, and this is where the acronym causes confusion.

CORSIA is a compliance instrument, built for airlines with obligations under it. A voluntary buyer funding sustainable fuel to address their own travel emissions is doing something different, and the certification they need follows the claim they intend to make rather than the scheme’s name.

In practice the frameworks overlap heavily, because the underlying question is the same: can this batch be traced, was it audited, and has anyone else already claimed it. A fuel certified under a CORSIA-recognised scheme has answered those questions, which is why the certification is useful evidence in a voluntary claim. Using that fuel against a CORSIA requirement is a separate step, taken by the airline under ICAO’s rules.

Is CORSIA the same as offsetting?

No, and the distinction is the one most worth remembering.

An offset pays for a reduction somewhere else, in an unrelated sector, and counts it against your own emissions. Insetting funds a reduction inside your own value chain: for aviation, that means real sustainable fuel entering the aviation fuel supply, reducing the emissions of the sector that is actually causing them.

What we do is insetting. The environmental attributes we trade come from certified fuel that goes into aircraft, and they are retired once to the party that funded them. CORSIA’s name includes the word offsetting because offsetting is still its main mechanism. Eligible fuel is how an airline reduces the amount it has to offset. Neither is insetting, and neither is what we sell.

What should a buyer take from this?

That the acronym on a certificate tells you which rulebook was applied, not how good the fuel is.

CORSIA recognition means a scheme has been assessed as competent to audit against ICAO’s criteria. It is a floor and a common language, which is exactly what a market this young needs. When you are handed a certificate, the useful questions are which scheme issued it, what it covers, and whether the reduction it records has been retired to you alone.

Somewhere in most fuel offers there is a line that reads something like “HEFA, ISCC CORSIA certified, mass balance”. Four or five capitalised terms, no punctuation between them doing any real work, and a buyer left to work out which one is the important one.

It is the wrong question. They are not comparable, and that is the whole difficulty: each one answers something different, and they happen to share a line.

Why do these names get mixed up?

Because nothing on the page tells you what kind of thing each one is.

Sort them by the question they answer and the confusion mostly dissolves:

Term	What kind of thing it is	The question it answers
HEFA	A production pathway	How was this fuel made?
ISCC, RSB	A certification scheme	Who checked it?
ISCC EU, ISCC CORSIA, ISCC PLUS	A rulebook within that scheme	Checked against which rules?
CORSIA, RED III	A regulatory framework	Whose criteria was it checked against?
Mass balance	A chain of custody option	How was it tracked through the supply chain?

Read that way, “HEFA, ISCC CORSIA certified, mass balance” is not a list of competing credentials. It is one fuel described from four angles.

What is HEFA?

Hydroprocessed Esters and Fatty Acids, and it is the route by which most sustainable aviation fuel is made today. It converts used cooking oil, animal fats, tallow and technical corn oil into jet fuel.

HEFA is chemistry and plant engineering. It is not a certification, it offers no sustainability assurance of its own, and a fuel being HEFA tells you nothing about whether anyone independent has examined the feedstock behind it. Two HEFA batches can have entirely different sustainability profiles depending on what went into them and where it came from.

This is the single most common mix-up we meet in proposals. HEFA sits in the “how it was made” column, never in the “who checked it” one.

What is the difference between ISCC EU, ISCC CORSIA and ISCC PLUS?

One certification body, three rulebooks, and the right one depends on the claim being made.

ISCC EU certifies against the EU’s Renewable Energy Directive, and our current certificate is issued under RED III. ISCC CORSIA certifies against the criteria ICAO set for international aviation. ISCC PLUS is the scheme ISCC runs for the markets those two do not reach; unlike the other two, its certificate names no regulation, and ours records a mass balance chain of custody.

Future Energy Global holds all three, so whichever rulebook a batch was certified under, its attributes reach you with the certificate intact. What we sell is for voluntary claims. A CORSIA certification describes the fuel. It does not make a purchase from us count towards an airline’s CORSIA requirement.

Does RSB work the same way?

Yes, and seeing it twice is what makes the pattern click.

Our single RSB certificate names four rulebooks: RSB Global, RSB EU RED, RSB ICAO CORSIA, and RSB Book and Claim. Same structure as ISCC. One body, several standards, selected by the market and the mechanism rather than by preference.

So the useful question is never “are you RSB or ISCC”. It is “which standard was this batch certified under, and does that standard answer the claim I need to make”.

Which acronym belongs in my claim?

The rulebook, and the certificate number that proves it.

A claim that says “HEFA fuel” describes a manufacturing process and commits to nothing. A claim that says “certified under ISCC CORSIA, certificate number ISCC-CORSIA-Cert-US201-209512025, retired to us and to no one else” is a statement someone can go and verify. The first is a specification. The second survives an audit.

When an offer arrives with a row of acronyms, the questions worth asking are short. Which standard, which certificate number, which chain of custody, and has the reduction been retired to anyone already. A supplier who can answer all four quickly is a supplier with the documentation behind them.

Two words that sound alike

Both words describe paying for an emissions reduction you did not make with your own hands. The difference is where the reduction happens. In carbon accounting, where is nearly everything: it decides which ledger the reduction can enter, and what an auditor will ask to see behind it.

What an offset is

An offset is a reduction or removal bought outside your own value chain. Funding forest protection, or a renewable energy project on another continent, to counterbalance emissions you have produced: the project is real, but it has no connection to the activities in your own inventory. The instrument that records it is usually a carbon credit, a tradeable unit representing one tonne of CO₂ reduced or removed by that external project.

Offsets have their own market, their own standards and their own debates. This lesson is not that debate. The point here is narrower: an offset compensates for your emissions somewhere else. It does not reduce them.

What insetting is

An inset is a reduction made inside your own value chain, where the emissions happen. If your people fly, the flights sit in your Scope 3, and aviation fuel is inside your value chain. When sustainable aviation fuel (SAF) replaces fossil fuel in that system, the reduction happens in the same chain of activity your inventory already counts.

That is the whole distinction. Not a better class of project: a different location in the accounts.

Where a SAF certificate sits

A SAF certificate records the verified environmental attributes of a batch of SAF: the lifecycle reduction, the feedstock, the pathway and the certification behind it. A registry allocates it to one owner and retires it once, so the claim is counted once. Because the fuel replaces fossil fuel inside aviation, the reduction reports against your Scope 3 travel or freight line, not as a purchase from outside your inventory.

A SAF certificate is an inset, not an offset, and it is not a carbon credit. The distinction is visible in the paperwork. Our May 2026 retirement on the RSB Book and Claim Registry names the batch, 36.213 tonnes of certified SAF at 80.674% below the fossil baseline, and names both claimants: Delta Air Lines on the Scope 1, our own legal entity on the Scope 3. A carbon credit names a project. A retirement statement names the fuel, and the registry lesson shows that machinery in detail.

What a SAF certificate does not do

The limits are part of the instrument, and knowing them is what makes the claim defensible.

It does not make a flight’s emissions disappear, and we will not describe it that way. It discharges no blending mandate, levy, or trading-scheme obligation: our volume sits in the voluntary market, above what regulation already requires. And the Scope 3 claim is capped at your actual footprint in the sector for that year, so a certificate can never say more than your own travel did.

For target setters, the SBTi Corporate Net-Zero Standard version 2 permits commodity certificates on a book-and-claim chain of custody, subject to its integrity criteria. Permits is the exact verb: the standard sets guardrails and leaves certification to the schemes that do it.

The question to take away

When someone shows you an emissions instrument, ask where the reduction happened. Outside your value chain, it compensates. Inside it, it reduces, and it can enter the ledger your targets are measured against. What a SAF certificate is and whose emission is whose are the next two steps.

The fuel with no biomass in it

e-SAF, also called power-to-liquid or PtL, is sustainable aviation fuel made from renewable electricity, water and captured carbon dioxide. There is no biomass anywhere in it: no cooking oil or tallow, and nothing grown for it. The carbon comes from captured CO₂, the hydrogen comes from water, and renewable electricity does the work of combining them into a fuel that meets the same technical standards as conventional jet fuel.

That makes it the clearest possible answer to a common mix-up. Most SAF today is a biofuel, but the two words are not interchangeable, and e-SAF is the proof: unambiguously sustainable aviation fuel, unambiguously not a biofuel.

Why it matters: the feedstock ceiling

Today’s SAF is mostly HEFA fuel, made from used cooking oil and tallow. Those are wastes, and wastes are finite: there is only so much cooking oil a planet fries. IATA puts 2025 production at 1.9 million tonnes, against roughly 500 million tonnes a year needed by 2050 for its member airlines’ net zero commitment. No waste stream closes a gap that size on its own.

e-SAF’s inputs are different in kind. Electricity, water and captured carbon are not capped by what kitchens and rendering plants throw away, which is why the European eSAF Coalition and the signatories of the Bodø Declaration argue it can scale beyond many biogenic routes.

Where it stands, honestly

Early. Electricity is the dominant cost, so e-SAF depends on cheap renewable power, and the first commercial-scale plants are still being financed and built. A tonne of e-SAF costs more today than a tonne of HEFA fuel, and both cost more than fossil jet fuel. Nobody serious in this market pretends otherwise.

The constraint is the same one the rest of the SAF market knows well. Producers need firm, long-term demand before a plant reaches a final investment decision, and buyers prefer to commit short. Somebody has to move first.

What we have signed

We have put our name on that early demand, and the record is public.

In April 2025 we signed the Bodø e-SAF Declaration, alongside e-SAF producers, manufacturers, airports, policymakers and NGOs. In the months after it, we signed Letters of Intent with two producers. One is with Carbon Neutral Fuels, for a portion of the future output of its planned UK Power-to-Liquid facility. The other is with Sora Fuel, covering the environmental attributes of the first 10 million gallons of its future e-SAF production.

A letter of intent is intent, not fuel. Both agreements are commitments to negotiate offtake, and we describe them that way deliberately. Their value is the demand signal: a named buyer on the other side of the table is part of what moves a plant towards financing.

What this changes for a buyer

Nothing about the accounting. When e-SAF volume flows, its verified environmental attributes move through the same Book and Claim machinery as every other batch: recorded on a registry, allocated to one owner and retired once. How a certificate works and what the registries do already cover the rules, and e-SAF changes none of them.

One registry, two names

Most people say “the IATA SAF Registry”, and the shorthand is understandable: IATA built it, announced it, and hosts it at safregistry.iata.org. The precise name is the CADO SAF Registry. It is operated by the Civil Aviation Decarbonization Organization, an independent body, and underpinned by IATA’s SAF Accounting and Reporting Methodology.

The split matters more than it sounds. A registry is the referee of the SAF market: it decides whose claim is whose. A referee owned by one side would be a weaker referee, so the operator is independent of the airlines whose fuel it records. When we write “IATA’s CADO SAF Registry”, both halves of that arrangement are in the name.

What it records

The registry records the environmental attributes of SAF batches: the certified reduction, the pathway and the chain of evidence behind each one. Attributes are transferred between account holders and retired to a single named owner, once, at which point the claim becomes usable and nobody else can ever make it. The registry lesson covers that machinery in detail, and it works the same way here as on any credible registry.

What makes this registry different is reach. It was built for a global market: airlines, fuel suppliers and corporate buyers on one system. A batch uplifted in one country can then support a claim held in another, without the evidence chain breaking.

What settled there first

We delivered the first transaction on IATA’s CADO SAF Registry: SAF Scope 3 certificates supplied to Microsoft, derived from Cathay Pacific’s purchases of sustainable aviation fuel. We had joined in the registry’s first cohort of users, and the transaction followed in June 2025, in the registry’s first months of operation.

The reason to say so here is not the flag. A registry is infrastructure, and infrastructure is proven by what runs on it. The transaction showed a corporate claim settle on the new system end to end, from an airline’s fuel purchase to a named buyer’s retirement statement.

Not the only registry, deliberately

Our transactions settle across independent registries: the RSB Book and Claim Registry, the Assure SAF Registry operated by 4AIR, and IATA’s CADO SAF Registry. In 2026, 4AIR and CADO began work on making their registries interoperable, which points where the market is heading: one set of rules for counting once, whichever ledger the entry sits on.

For a buyer, the registry name matters less than what the entry gives you: a retirement statement naming the batch, the reduction and you. What a SAF certificate is shows what that document records.

Why there is no list price

A SAF certificate records the verified environmental attributes of one specific batch of fuel, so its cost follows that batch. What the fuel was made from, how it was made, who certified it and where it was delivered all move the number. Two certificates can be equally valid and priced differently, for the same reason two valid insurance policies are.

That is why this page explains the drivers rather than quoting a figure. A number without its batch behind it would tell you very little, and it would be out of date by the time you read it.

The four drivers

Feedstock

Most SAF today is made from used cooking oil and tallow, and waste feedstocks have their own supply constraints: there is only so much of them. Scarcer inputs cost more, and the report we published with PA Consulting maps how those constraints shape the market.

Pathway

HEFA fuel from waste oils is the established route. Newer pathways, e-SAF above all, come with the costs of first-of-a-kind plants and depend on cheap renewable electricity. Their fuel is dearer while the technology scales.

Certification and evidence

A certificate that survives an audit rests on a certified chain of custody, an independent registry entry and a retirement statement. That evidence chain is part of what you are paying for, and a cheaper claim without it is not the same product.

Commitment

Volume and duration move price in this market as in any other. Producers value firm, multi-year demand, and price it accordingly.

The premium, plainly

SAF costs more than fossil jet fuel, and we won’t pretend otherwise. On EASA’s reference prices, bio-based SAF stood at 2.84 times the price of conventional jet fuel in 2024 and 3.01 times in 2025. Absolute prices have fallen; the ratio has not closed.

The honest frame is what the premium buys. A retired certificate gives you a verified, registry-backed reduction inside your own value chain, with documentation an auditor can trace from the batch to your claim. The premium is also the demand signal this market runs on. Firm corporate demand can give producers the confidence to invest in future capacity, and that is how supply grows over time.

Getting to an actual number

A real quote needs three inputs: the footprint you are addressing, the scope you would claim against, and the volume and duration you can commit to. With those, the conversation is short, and the number comes with the batch evidence attached. That is the conversation to start with us, and the corporate buyer’s guide covers what to establish internally first.