In this episode of Sustainability in the Air, Conor Madigan, founder and CEO of Aether Fuels, joins SimpliFlying CEO Shashank Nigam to talk about how his company plans to make sustainable aviation fuel both cheaper and more scalable by converting abundant waste carbon into drop-in fuels.
Aether Fuels is a young company with a unique origin. Madigan did not arrive at sustainable fuels through a long career in energy; he started with a blank sheet of paper, chose the problem first, and built the technology around it. That problem is now one of the most pressing in aviation decarbonisation. The dominant SAF pathway today is approaching a feedstock ceiling, because of which Aether is betting instead on the waste carbon the world already produces — biogas, agricultural and wood waste, industrial off-gases, and eventually CO2 itself, should hydrogen economics improve — to address this gap.
Here are the key highlights of the conversation:
How an electrical engineer ended up founding a SAF company (2:49)
Four years from blank sheet to commercial plant (12:14)
The road to commercial production by 2028 (16:29)
What Singapore offers as an ecosystem for tough tech (24:40)
Turning waste carbon into jet fuel: the Aurora process (31:01)
Progress on airline offtake agreements (45:40)
The single biggest constraint on scaling (58:20)
Rapid Fire! (1:04:08)
Keep reading for a detailed overview of the episode.
Why moving beyond the HEFA ceiling matters
Almost all of the sustainable aviation fuel (SAF) that airlines can actually buy today is made through a single process. The HEFA route takes waste fats, oils and greases, most commonly used cooking oil, and hydrotreats them into a drop-in fuel. Even though it works well, its limitation is mathematical: there is only so much waste fat in the world, and those feedstocks are already in demand for other fuels.
That is the constraint Aether Fuels was built to address. Madigan puts the timeline plainly: “People generally say that by the time we get to 2030 and the next tranche of mandates kick in, that the current HEFA technology will not be able to keep up with the global demand.”
As blending mandates tighten across Europe, Singapore and Japan, the gap between what airlines are required to buy and what HEFA can supply becomes a hard commercial reality. The honest response to that gap is uncomfortable, because the alternatives are harder.
Waste carbon feedstocks such as CO2, biogas and biomass are abundant, but they look nothing like a jet fuel molecule; making fuel from them means synthesising it almost from scratch, which demands far more complex and expensive plants.
Aether’s argument is that this capital cost problem is solvable, and that solving it is precisely what unlocks SAF at the volumes aviation needs. It is also a contrarian bet: Aether chose to back feedstocks it judged abundant and affordable rather than wait, as many e-fuels companies have, on cheap hydrogen.
Five ways Aether Fuels is rethinking how SAF gets made
1. Starting with the problem, not the technology
Madigan’s career began far from energy. He holds a PhD in electrical engineering, and his first company, Kateeva, was an OLED display manufacturing company. When he decided in 2020 to move into climate technology, he resisted the temptation to begin with a favourite idea.
Instead, he spent close to eighteen months with incubators and investors, generating and discarding problems to solve, before settling on drop-in sustainable fuels for industries that cannot electrify. Aviation and ocean shipping fitted those constraints precisely: both are large emitters, both depend on liquid fuels, and neither can simply plug into a battery.
Only then did Madigan go looking for a technology to match it, spending close to a year studying research institutes and rival approaches before licensing the foundational process from GTI Energy near Chicago.
He describes the sequencing as deliberate. Because, as he puts it, “since we started problem first, technology second,” the company could measure every technical option against a clear test of what would actually scale.
For a founder entering an unfamiliar field, that discipline doubled as a credibility test he had to pass with deep domain experts before they would entertain him.
2. Making a contrarian bet against cheap hydrogen
The most consequential decision Aether made early on was about what not to chase. In 2022, the highest-profile companies in synthetic fuels were building their plans around CO2 combined with hydrogen, and many were investing heavily in electrolysers. Aether looked at the same roadmaps and reached a different conclusion.
The reasoning came down to cost. E-fuels made from CO2 and hydrogen only work economically if hydrogen becomes very cheap, and Madigan was not persuaded that the optimistic price forecasts would hold.
As he explains: “We actually loved the idea of e-fuel and CO2 plus hydrogen, but we just couldn’t get comfortable that the cheap hydrogen would be available.”
So Aether built its strategy around biogas, biomass and industrial off-gases, while keeping its technology capable of handling CO2 and hydrogen should the economics improve. Madigan calls this being feedstock flexible. At the time it was an unpopular stance; he argues that more companies are beginning to appreciate the value of feedstock flexibility, as the abundance and affordability of waste carbon becomes harder to ignore.
3. Its Aurora technology attacks capital cost head-on
Converting waste carbon into jet fuel is chemically demanding. Unlike used cooking oil, which already resembles a fuel molecule, a feedstock such as CO2 must be stripped of its oxygen and rebuilt into fuel. That synthesis requires complex plants, and complexity is expensive; the result, Madigan says, is an industry-wide problem of low-value feedstock paired with very high capital cost.
Aether’s answer is a package it calls Aether Aurora. On the front end, a process named tri-conversion merges two reaction steps that are normally run in separate reactors. “We essentially cut in half the cost of that section of the plant, which is already the majority cost of the plant,” Madigan explains.
An electrified reactor, which uses electricity rather than burning feedstock to generate heat, improves yield relative to feedstock input by roughly 20%. At the back end, novel catalysts remove costly separation and hydrogen-recycle steps, cutting the upgrading section’s cost by roughly half again.
Taken together, these innovations are designed to reduce capital cost and raise yield at the same time. That combination is what makes smaller, waste-fed plants commercially viable, and, in Madigan’s view, potentially undercut HEFA over time.
4. Choosing Singapore as the place to scale tough tech
Aether’s first commercial plant, Project Beacon, will not be built in the United States, where its pilot and demonstration lines are situated. It will be in Singapore, and the choice reveals a great deal about how Madigan thinks about scaling hardware.
Building a commercial facility means securing infrastructure, utilities, partners and policy support all at once. In Singapore, Aether found a partner in Aster, which had recently bought a world-scale refinery previously run by Shell and had spare space within it. The deal moved quickly; Madigan says it took only about ten weeks from the first serious meeting to a yes. Helping it along were Aether’s existing ties to Temasek, the Singapore sovereign wealth fund behind its anchor investor, Xora.
What Madigan values most is predictability. Multi-year projects need stable policy, and he contrasts Singapore’s orderly, systematic civil service with the volatility he sees elsewhere.
“If you build the relationship and partnership there and demonstrate your commitment to Singapore, they support you,” he says. The result is Project Beacon, a 2,000-tonne-per-year plant due to begin operating in 2028, and a model Madigan believes other countries trying to seed tough tech industries could study.
5. Refusing to sign offtakes for plants that do not exist
For a pre-revenue company, signing offtake agreements with airlines is tempting, since it signals demand and reassures investors. Aether has largely declined to do so, and Madigan is candid that investors have pushed back.
His objection is principled. Speculative offtake deals for plants that don’t yet exist, he argues, serve nobody: “it doesn’t do anybody good to go do offtake agreements on plants that have not been built yet and that don’t have firm economics.”
Aether has two public memoranda of understanding, with JetBlue and Singapore Airlines, and has opened conversations with around ten airlines; it intends to hold serious offtake discussions only once it can bring concrete, costed projects to the table.
Madigan says the airlines themselves appear to appreciate the restraint. It also points to what he sees as the real long-term bottleneck. That caution reflects the realities of scaling physical infrastructure. Madigan notes that Aether spent roughly four years moving from concept to a one-barrel-per-day demonstration plant in North Carolina, a pace he argues is actually fast for industrial hardware. “Hardware takes a long time,” he says, contrasting the timelines of fuels infrastructure with software startups.
The constraint on scaling, in his view, is not the chemistry; it is moving projects through engineering and financing to a final investment decision, a process where, by his estimate, many projects ultimately fail simply because they cannot attract enough interest to get funded.
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