What if we could produce fuel using the CO₂ already present in the air?
The idea almost sounds too simple to be believable. It conjures up the image of gasoline “made from air”—clean, circular, almost magical. The reality, however, is far less romantic. Synthetic fuels, or e-fuels, do not defy the laws of physics; they work within them, at a significant energy cost.
And yet, at a small scale, it works.
Aircela’s Machine: 4 Litres of Gasoline per Day, Directly from Ambient Air
In New York, startup Aircela has demonstrated that it is technically possible to produce gasoline without using crude oil—directly from the air. Their refrigerator-sized machine captures CO₂ from the atmosphere and converts it into fuel that is chemically identical to the gasoline found at service stations.
The process is simple in principle:
- The machine draws in ambient air through a potassium hydroxide–based filter, which captures the CO₂ (around 10 kg to produce 4 litres of gasoline).
- Hydrogen is produced by water electrolysis powered by solar energy.
- The captured CO₂ and hydrogen are combined inside a reactor with a catalyst, converting them first into methanol and then into gasoline.
The result: 4 litres of gasoline per day, with no crude oil and no direct emissions during production. The fuel produced is chemically compatible with existing vehicles and fuel infrastructure.
The first takeaway is that this is no longer science fiction—it is already operational in a pilot phase in Los Angeles. However, the machine is estimated to cost between €14,000 and €18,500, with a production cost of around €0.36 per litre of fuel, excluding equipment depreciation.
To understand e-fuels, we first need to let go of a common misconception: we are not producing fuel “from air” in any magical sense. Instead, we are synthesizing carbon-based molecules from three very real ingredients: CO₂, water, and—above all—a large amount of electricity.
The CO₂ can either be captured directly from the atmosphere through Direct Air Capture (DAC), as Aircela does, or recovered from concentrated industrial sources. Companies such as Axens, IFP Energies nouvelles, and SMS group are actively developing these technologies.
Water is then split into hydrogen through electrolysis, an energy-intensive process.
Finally, the hydrogen and captured CO₂ are recombined to produce liquid fuels such as synthetic gasoline, diesel, or kerosene.
On paper, the result is compelling: fuels that are fully compatible with today’s engines and infrastructure. In practice, however, it is a system that converts electricity into liquid fuel—with significant energy losses along the way.
The Real Challenge Isn’t Carbon, it’s Energy
E-fuels are often presented as a way to “recycle carbon.”
Today, burning petroleum releases fossil carbon into the atmosphere, increasing the concentration of CO₂.
E-fuels work differently: the carbon they contain comes from CO₂ that is already present in the air. When the fuel is burned, that CO₂ is released again and can, in principle, be captured once more. The goal is not to eliminate emissions altogether, but to avoid introducing additional fossil carbon into the atmosphere.
This creates a closed carbon loop.
But this perspective overlooks the real challenge: the main limitation of e-fuels is not carbon—it is the availability of abundant low-carbon electricity.
Aircela powers its electrolyzer with solar energy. Scaling this approach to an industrial level, however, would require vast amounts of renewable electricity.
Aircela alimente son électrolyseur avec de l’énergie solaire. Mais multiplier cette approche à l’échelle industrielle nécessiterait des quantités colossales d’électricité renouvelable.
What the Numbers Really Tell Us
Aircela perfectly illustrates this paradox: the technology is technically viable, but highly energy-intensive. Producing just 4 litres of gasoline per day already requires a system estimated to cost between €14,000 and €18,000. Scaling this model to millions of vehicles would be both economically and energetically unsustainable.
The debate goes beyond the technology itself. E-fuels are not only competing with fossil fuels—they are also competing with every other use of low-carbon electricity.
That same electricity could be used to electrify transport, heat buildings, decarbonize industry, produce hydrogen for steelmaking, or help stabilize power grids.
Yet low-carbon electricity is a scarce resource and is already heavily relied upon in virtually every energy transition scenario.
Producing e-fuels therefore means making choices about how to allocate that electricity—often away from applications that are significantly more energy-efficient.
That said, e-fuels are not a dead end. They become particularly relevant where direct electrification reaches its limits.
Aviation is the most obvious example, along with long-distance maritime transport and certain industrial applications.
In these sectors, the energy density of liquid fuels remains extremely difficult to replace.
Aircela is initially targeting private users who want to produce their own fuel. However, this remains a niche model and is not well suited to large-scale mobility, where direct electrification is far more efficient.
A Practical Constraint, Not a Revolution
E-fuels need to be viewed in the right perspective. They do not produce energy—they transform it, with significant losses along the way.
They do not allow us to preserve our current energy system in a simply “greener” form. Instead, they help sustain specific applications where no straightforward alternative currently exists.
Aircela demonstrates that the technology works, but it does not change the laws of physics: efficiency remains low, costs remain high, and low-carbon electricity remains the critical resource.
In Summary
E-fuels are:
- A way to convert electricity into liquid fuel
- An energy-intensive option (10–20% overall efficiency)
- A niche solution for sectors that are difficult to electrify
- A reminder that low-carbon electricity is the key resource of the energy transition
Aircela adds an important nuance: the technology genuinely works, even at a domestic scale. But that does not change the overall energy balance.
Put simply, the main limitation of e-fuels is not their technical potential—it is their energy efficiency.
They are a relevant form of energy storage only when operational constraints outweigh the efficiency losses, such as in aviation, maritime transport, and a handful of highly specific applications.
For everyday mobility, battery-electric vehicles remain the objectively superior solution.
