The Curious Case of Alcohol-to-Jet (ATJ) SAF
Elvis Ebikade, PhD · June 9, 2026
The technology works; the real test is the feedstock. A step-by-step look at why the cheapest ethanol can't fly, why the sustainable ethanol still costs too much, and what it takes to unlock ATJ SAF.
In November 2025, LanzaJet did something the aviation-fuel world had been waiting fifteen years to see. At its Freedom Pines Fuels plant in Soperton, Georgia, the company produced on-spec jet fuel from ethanol at commercial scale, the first time anywhere that a renewable feedstock that is neither an oil nor a fat has been turned into sustainable aviation fuel in a commercial facility. That is a real milestone, and it earned the celebration it received. And it should reframe the most important question in the alcohol-to-jet (ATJ) story, because if the hard part was supposed to be the conversion technology, Soperton is evidence that the hard part is largely behind us. This is a question that touches everyone along the SAF value chain at once, and rarely in the same room: the producer deciding where to build, the financier deciding what to underwrite, the airline deciding what to buy, and the standards body deciding what qualifies.
What follows is meant to be read from any of those seats, as a shared map of where the real bottlenecks sit and reframes the usual rallying cry. Much of the SAF conversation calls for more fuel and more pathways, and we do need both. But the sharper question is whether a given pathway can stand on its own economics, because a pathway that pencils out is the one that actually gets financed, built, and scaled. To see where ATJ really stands, start with the converter, because its maturity is what moves the spotlight onto everything around it.
The technology is no longer the hard part
The good news is how far the conversion technology has come. ATJ chemistry is easy to state: dehydrate the alcohol, link the pieces together through oligomerization, hydrogenate, and fractionate into jet-range hydrocarbons. None of that is experimental anymore. The pathway has been certified under ASTM D7566 (Annex A5) for ethanol and isobutanol at blends up to 50%, and the roster of technology providers is deep and competitive. Alongside LanzaJet's own process, Axens markets its Jetanol technology as the route selected by most of the world's major ethanol-to-jet projects and licenses it to engineering partners such as Praj Industries, which recently demonstrated an integrated ethanol-to-jet process in India. This achievement makes Praj the first company globally to offer a fully integrated, end-to-end technology and engineering solution for the ATJ pathway. Honeywell UOP calls its ethanol-to-jet process "ready now," and it has been picked up by Summit Next Gen on the US Gulf Coast, by Taiyo Oil Company, Limited in Japan, and, as of April 2026, by Petrobras for what would be the first large-scale ethanol-to-jet project in Latin America. Gevo, Inc., meanwhile, centers its ATJ model on climate-smart agriculture and its Verity platform through which growers can maximize ag value by tracking attributes achieved by their crops throughout the value chain carbon platform, linking fuel production to quantified carbon reductions. Even the old knock on ATJ, that it yields a paraffinic kerosene needing aromatics blended back in, is being answered: Swedish Biofuels and KBR, Inc. have developed an aromatics-inclusive route (ATJ-SKA, the eighth annex to D7566), certified at a 50% blend today like every other approved pathway, but built to point toward a fully formulated fuel over time because it produces aromatics alongside the paraffins.
So why hasn't it scaled?
If the technology is this mature, why has ATJ not scaled the way many of us expected? The answer likely sits upstream, in the ethanol feedstock itself. While there is no shortage of ethanol in the world; the difficulty is that almost all of it is first-generation, made from corn, sugarcane, or wheat. Furthermore, first-generation ethanol faces a set of overlapping challenges when it tries to become jet fuel. The first is carbon intensity: in the techno-economic work published by the National Laboratory of the Rockies (NLR), corn-grain ethanol-to-jet reduces lifecycle emissions by roughly 22% against fossil jet before any renewable-energy or carbon-capture credits, a real reduction but a modest one against the deeper cuts buyers and compliance frameworks increasingly expect, and depending on the lifecycle methodology and assumptions, especially land-use-change penalties, it can look worse still. The second is less about chemistry and more about people: many airline sustainability teams are cautious about food-based feedstocks, on both indirect-land-use-change grounds and the plainer reputational calculus around food versus fuel. And the third, which we will return to, is competition: ethanol is wanted across road transport and chemicals too, so aviation is not the only bidder for it. None of these makes first-generation ethanol unusable for SAF, technically, but together they make it a challenged starting point, commercially, and the SAF industry's response of the past several years follows naturally: a search for ethanol that is lower in carbon, less contested for, and not tied to your bowl of corn flakes.
That search leads to second-generation, or cellulosic, ethanol, made from agricultural, forestry residues, and energy crops instead of food crops. On paper it is the elegant answer; NRL puts corn-stover ethanol-to-jet at around a 77% lifecycle reduction, and with carbon capture the same route can reach net-negative CI territory. However, cellulosic ethanol has taken far longer to mature than its early champions hoped, having been described as roughly five years away for two decades. The first commercial wave of the 2010s was a genuine act of pioneering, built with substantial public support, and much of it ran into difficulties that taught the field a great deal: Abengoa's roughly $500 million Hugoton plant in Kansas idled within about a year of opening and was later sold for a fraction of its build cost; POET-DSM's Project Liberty in Iowa worked through persistent pretreatment challenges; DuPont's plant in Nevada, Iowa was sold and repurposed; and BP redirected a flagship Florida project before construction. The distance between promise and delivery was wide enough that the EPA has repeatedly adjusted the cellulosic targets in the Renewable Fuel Standard, a reminder of how demanding this chemistry has proven at scale.
A new cohort is building now. Clariant, Praj Industries, and Brazil's Raizen, among others, are putting commercial cellulosic capacity in the ground, and Raizen in particular deserves real credit as an early pioneer and, for a time, the only player operating at commercial scale, with fifteen years and more than one hundred million euros invested and the world's largest cellulosic plant at Bonfim. Its experience is also the industry's most candid window into how demanding the economics still are: through 2025 the company has navigated real financial headwinds, with consecutive quarterly losses, second-generation output that dipped even as new capacity came online, heavy project-linked debt, and an open review of its portfolio that may include bringing partners into its cellulosic plants. The takeaway is not that second-generation ethanol cannot work, but that cost, rather than chemistry, is the gate.
The first driver: cost
What is worth watching, then, is where the cost of second-generation ethanol can actually be moved, and it pays to be specific, because the levers are distinct and interact. There are three: the feedstock, the process that converts it to ethanol, and the full slate of products that process yields from the lignocellulosic feedstock. The process is where most of the cost hides, and it is really three steps in series, pretreatment, hydrolysis, and fermentation, each with its own cost-versus-yield tradeoff that propagates downstream.
Pretreatment breaks down the recalcitrant lignocellulosic matrix to make the cellulose accessible, and it has historically been the most capital- and energy-intensive step. SAFFiRE Renewables, originally backed by Southwest Airlines and acquired by Conestoga Energy in 2025, is built on NRL's deacetylation and mechanical refining (DMR) process, which runs at low temperature and pressure and is reported to cut enzyme loading; since enzymes can account for a large share of conversion cost, a credible reduction there moves the cost stack meaningfully.
Hydrolysis, which depolymerizes the pulp into fermentable sugars, is a sharper fork than it looks. Acid hydrolysis is cheaper but generates furfural and HMF, degradation products that inhibit the fermenting yeast and lower ethanol yield; enzymatic hydrolysis delivers a cleaner, more selective sugar stream but carries the enzyme cost just mentioned. So the cheaper unit operation can quietly tax the next one, and the true cost only shows up at the fermenter. That coupling, not any single step, is what makes 2G economics so unforgiving, and why a plant must be optimized as a system rather than step by step.
The third lever, the total product slate, is where the first wave most often broke, and it is a chemistry problem with a balance-sheet consequence. Cellulosic processes leave behind lignin, and how you treat the biomass determines what that lignin is worth. Harsh, high-acid pretreatments drive condensation reactions that collapse lignin's native beta-O-4 ether linkages into a recalcitrant, carbon-carbon-bonded structure, good for little beyond boiler fuel, which strands a third of the biomass at near-zero value and forces the ethanol to carry the entire project economics. Bioleum's organosolv route works on this axis: by fractionating under milder, low-acid conditions, it aims to preserve a more native-like, beta-O-4-rich lignin amenable to upgrading into aromatic fuels and chemicals. If the lignin becomes a revenue stream rather than a disposal problem, the whole product slate carries the economics, not the ethanol alone. Chemistry is well established, but whether it clears at commercial scale is the open question.
Feedstock sits underneath all of it, shaping both logistics and reactor behavior. The bamboo biorefinery Numaligarh Refinery Limited brought online in Assam in 2025, with Fortum and Chempolis Ltd., is instructive on this lever: bamboo's higher bulk density and uniform morphology make it cheaper to store and transport and easier to chip and feed than loose, low-density cane straw or bagasse, which tend to bridge and channel in the reactor, creating mass-transfer and plugging headaches that erode uptime. Better feed handling is not a footnote; in a continuous biorefinery, uptime and consistent solids loading are gating variables for unit economics. A complementary move is to engineer the feedstock itself. Bioleum Corporation's Hexas Biomass platform centers on a purpose-grown perennial grass whose biomass yield per acre runs well above agricultural residues like corn stover or bagasse and other energy crops like miscanthus and switchgrass, and that grows on marginal, saline, or contaminated land rather than competing for cropland, sidestepping the food-versus-fuel concern entirely while its deep root system sequesters carbon and lowers the feedstock's carbon intensity. A dense, high-yield, low-CI crop tightens the two variables that dominate 2G economics at once, delivered cost per ton and carbon intensity, and pairing it with the milder organosolv fractionation discussed above is an attempt to push the feedstock and product-slate levers together rather than one at a time. None of this proves any single project has cracked the economics, no one can claim that yet. Feedstock, the three process steps, and the product slate are the levers, and the prize is not a saving in any one of them but a plant that pencils as a whole, with every product finding a market that values it.
Solving that 2G cost equation will take time, and while it matures, there are nearer-term ways to lower the carbon intensity of the ethanol we already make, which matter because ATJ economics are extraordinarily sensitive to both the price and the carbon intensity of the ethanol going in. The most immediate of these is "Generation 1.5" corn-kernel-fiber ethanol, which pulls the cellulosic sugars out of the fibrous shell of the corn kernel inside dry mills that already exist. It is an elegant piece of value engineering: the fiber is a captive feedstock that arrives with the corn at no extra harvest, collection, or transport cost. In the United States, the EPA recognizes it as a crop residue, so the resulting ethanol qualifies as cellulosic and earns the corresponding D3 RIN credits. One nuance: corn kernel fiber tends to carry a higher CI than residue- or energy-crop cellulosic ethanol, since the fiber would otherwise have gone into livestock feed; it is a real and fast-growing low-carbon on-ramp rather than the lowest-carbon option in the family. Carbon capture offers a complementary lever, cutting the carbon intensity of conventional corn ethanol sharply for a relatively modest increase in cost, per LCA modeling. Both share a decisive advantage over greenfield cellulosic: they ride on the more than 180 ethanol plants already operating across the US rather than demanding first-of-a-kind capital.
The second driver: sustainability
These bridges carry a caveat that reveals how the market actually clears. A producer can do everything right to secure low carbon intensity, carbon capture in place, a technically clean, well-documented and traceable feedstock, and still meet apprehension at the airline procurement table, simply because the feedstock is corn. The biology is on the producer's side, since the overwhelming majority of US corn is grown for feed and industrial use rather than the dinner plate, yet the food-versus-fuel association attaches to the crop itself, and for many sustainability teams it does not dissolve just because the carbon math improves. The lesson for anyone building in this space is that clearing the carbon-intensity bar is necessary but not always sufficient; the feedstock has to clear the buyer's sustainability narrative test as well.
That sustainability narrative test is far stricter in aviation than in road transport, and the reason is likely structural rather than emotional. When a contested feedstock goes into road fuel, it disappears into a vast pool consumed by millions of individual drivers, with no single party an outside critic can readily hold to account. In aviation, the same feedstock lands on the books of a named airline, and that concentration of accountability changes the risk calculus entirely. The precedent is now set: in March 2024 the District Court of Amsterdam ruled that a series of KLM sustainability advertisements, including claims built around SAF and offsetting, were misleading under EU consumer law, the first binding greenwashing judgment against an airline anywhere, and environmental groups have since put dozens of other carriers on formal notice. The ruling turned on advertising language rather than any specific feedstock, but the signal to procurement teams is unmistakable: every sustainability claim an airline makes, including the provenance of the fuel it buys, may be tested in public and in court. A feedstock that invites the food-versus-fuel critique is therefore not merely a reputational question but a litigation-exposure one, which is a different order of caution.
This instinct is now written directly into how the industry defines eligible feedstock. Many carriers and leading producers publish sustainability policies that explicitly rule out palm-derived materials; SkyNRG, for instance, states plainly that it does not use food crops such as soy and palm because of their deforestation risk. The European framework goes further, with ReFuelEU Aviation excluding food and feed crops, palm- and soy-derived materials, and palm fatty acid distillate outright. Palm tends to be named most explicitly, while soy sits in the same category but is treated a little more quietly, and the telling contrast is that soybean or canola oil is used freely to make renewable diesel for the road, where the same feedstock and chemistry raise far less objection. What differs is not the science but the exposure that attaches once the fuel is tied to a specific product-market dynamic rather than dispersed across a fuel pool.
The caution then travels one step further downstream, to the customer who pays. Much SAF is bought by corporates retiring Scope 3 travel emissions under science-based targets, so even an airline comfortable with a low-carbon corn pathway has a second test to pass: carrying that feedstock story onward to a buyer working within its own commitments. Two narrative tests in series, not one.
Here the third challenge returns: even setting sentiment aside, ethanol is wanted nearly everywhere else. Road-fuel blend mandates have been climbing across markets, pulling ethanol into gasoline, and ethanol is also a renewable building block for chemicals, with Braskem already making ethylene from it at scale in Brazil. A feedstock with that many homes does not sit quietly waiting to become jet fuel at a discount. Aviation, in other words, is not only working to lower ethanol's CI and clear its narrative tests; it is competing for the feedstock itself against sectors that often value it just as much. Which is why an interesting development in the ATJ family right now is not about ethanol at all.
A different feedstock: methanol
Methanol-to-jet is moving from concept toward commercial reality: ASTM qualification is anticipated in the 2026 to 2027 window, the global project pipeline already represents on the order of 1.8 million tonnes per year of capacity, and the technology bench is serious, spanning ExxonMobil, Honeywell UOP (through its eFining process), Topsoe, and venture-backed entrants such as Switzerland's Metafuels. Two things make methanol compelling. The first is processing, where several analyses, including recent work convened through the Methanol Institute, point to methanol-to-jet as one of the more cost-favorable of the emerging routes on its own merits. The second is more fundamental: methanol is one of the largest commodity chemicals on the planet and can be made many ways, which leaves it far less exposed to the single-feedstock bottleneck that constrains ethanol-ATJ. That feedstock flexibility is also what connects this story to the next one. Methanol need not come from natural gas; you can gasify waste and residual biomass into synthesis gas and convert that syngas into methanol, or make e-methanol from captured CO2 and green hydrogen, the route Honeywell's eFining is built around. The biomass-gasification path is especially worth watching, because it turns the feedstock question inside out: instead of competing for a liquid feedstock everyone already wants, you begin with low-value residues and build value upward. That same gasification step is the front end of Fischer-Tropsch, the third pathway in this feedstock arc and the subject of the next piece in this series.
What it will take for ATJ to take off
Underneath all of this is a single discipline worth saying plainly: the aim is not for ATJ to be one more option on the SAF menu, but for ATJ to stand on its own as a solid, reasonable pathway with a credible economic case for demonstrating project viability and bankability. And the feedstock arc traced here is exactly what makes that demanding, because cost and sustainability often pull in opposite directions. The cheapest ethanol, first-generation and Generation 1.5, is the kind aviation is most cautious about on sustainability grounds, while the feedstocks that clear the sustainability bar most convincingly, advanced cellulosic and waste-gas ethanol, are for now the costliest and least abundant. The feedstock that qualifies is the expensive one, and that tension, more than the converter or the chemistry, is what determines whether ATJ SAF is genuinely viable or merely available.
The constructive news is that this is a solvable problem, and the work points in two clear directions. One is to drive the delivered cost of the sustainability-qualifying feedstock down: intensifying 2G and 3G processes, capturing co-product value, siting plants where residues or waste gases arrive cheaply, and scaling deliberately so that the advanced ethanol which qualifies today also delivers economically viable and bankable projects. The other is to widen the set of feedstocks that can clear the sustainability bar in the first place, improving the carbon and land-use profile of cheaper ethanol so more of it earns a place in aviation. Brazil's second-crop, or safrinha, corn is an instructive case: grown in the dry-season window after soybeans on land already in production, it carries a materially better land-use story than conventional corn, though it still has to answer the food-versus-fuel question that follows any grain into a jet tank. Neither path is simple, but both are real, and progress on either improves ATJ's standalone economics directly. Better still, the gains compound: when one producer drives a pathway's delivered cost down, the whole pathway benefits, so the case for ATJ and the whole SAF industry strengthens with every step.
There is a structural reason all of this matters so much. For ATJ to scale, leaning on first-generation ethanol is harder than it first appears: that feedstock is already in demand from road fuel and chemicals, and it faces real headwinds at the airline procurement table on sustainability grounds, so it is challenged rather than disqualified. The more durable runway for ATJ increasingly looks like it runs through second- and third-generation ethanol. Tellingly, this is where the field's own pioneer is now pointing. LanzaJet, whose Soperton plant opened this story, is increasingly leaning on the gas-fermentation lineage of its sister company LanzaTech for non-food ethanol: its UK Project DRAGON will feed the same alcohol-to-jet process with ethanol made from waste gases and, in a later phase, from captured CO2 and green hydrogen, rather than from corn. The signal is even clearer in how Soperton itself is being used; rather than running on cheap, abundant corn ethanol, the plant offers a tolling model, a practical reflection of the fact that the ethanol airlines want for SAF is the non-1G kind, and that it is not yet available cheaply or at scale. LanzaTech's own framing, that the future of aviation fuel is ethanol-to-SAF, only holds if that ethanol is the kind aviation can actually use.
It is a fitting place to close, because it completes the arc that Soperton began. The intuitive playbook for a project developer has been simple: license a proven converter from LanzaJet or Honeywell, secure abundant and cheap first-generation ethanol, and sell the resulting SAF to airlines to meet their decarbonization commitments. What last year has shown is that this playbook runs into a wall that has nothing to do with whether the technology works, because it plainly does. The wall is that producing the fuel is now a commercial constraint; delivering fuel that is cost-competitive, CI-competitive, and sustainable enough to be uplifted on a plane is. LanzaJet's pivot toward non-1G ethanol is the industry working the sustainability side of that, carbon intensity included. The cost side is still ahead of everyone. Today a mandate-and-penalty regime can make expensive SAF pencil on paper, but leaning on penalties is not the same as being genuinely competitive, and the real prize is a non-1G ethanol pathway that is genuinely cost-competitive in its own right.
None of these argue against developing new pathways; we need that pioneering work. The point is that proving technical feasibility cannot be where the effort stops, with the high costs simply passed to airlines. Both things have to be true at once: a pathway has to be technically sound, and it has to reach genuine economic viability while delivering real sustainability value. So if the gate is no longer the converter but the feedstock, are we structuring projects and supply chains around securing cost-competitive, CI-competitive, and sustainable ethanol, rather than assuming the cheapest available will do? Are we scaling 2G and novel ethanol pathways with the urgency we gave the conversion step? And in policy, are we just stamping new pathways while the bottlenecks that carry an existing one from technically feasible to commercially viable go unaddressed, or are we funding those bottlenecks directly, the way targeted support for 2G ethanol would for ATJ SAF? A pathway is only as viable as its bottleneck. So I will leave it there: from your seat in this chain, where do you see the bottleneck, and what would it take to unlock it?
Elvis Ebikade, PhD · Founder & Principal, Vansam Advisory, an independent SAF commercial-strategy firm that translates technology and technical work into the commercial case for cost, carbon intensity, offtake, and capital.
