Will Airplanes Ever Stop Burning Kerosene? The Real Story Behind Sustainable Aviation Fuel

What if the sky — that vast, blue canvas we love to gaze at — could stay clean while we still soar through it?

Welcome to FreeAstroScience, where we break down complex scientific principles into simple terms. We’re glad you’re here. Whether you’re a frequent flyer curious about what powers your next trip, a science enthusiast hungry for hard numbers, or someone who simply cares about the planet beneath those flight paths — this one’s for you.

Today, we’re tackling a question that’s been circling the aviation world like a plane in a holding pattern: Can we really replace kerosene? The answer, as we’ll discover, is equal parts hopeful and sobering. We’ve got real dates, real costs, real chemistry, and a few surprises along the way.

Stay with us to the end. The details matter. And so does your understanding.

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The Race to Replace Kerosene: Can Aviation Really Go Green?

What Exactly Powers Today’s Commercial Aircraft?

Let’s start at the beginning. Every time a commercial jet takes off, it burns a fuel called **Jet A-1 — a mixture based almost entirely on kerosene, which comes from distilling crude oil .

That’s right. Oil. The same finite resource that shakes global markets every time there’s a conflict, an embargo, or a pipeline disruption.

Here’s a number that puts things in perspective: **more than one-third** of the kerosene used across the European Union is imported . And of that imported share, nearly half comes from the **Persian Gulf** — a region vulnerable to geopolitical chokepoints like the Strait of Hormuz . The rest arrives from India and other countries that have been cutting back their exports, worried about their own energy security .

When one domino falls, the rest follow. In a connected world, an energy problem never stays local.

So the question isn’t just environmental. It’s strategic. It’s economic. And it’s urgent.

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What Are SAF — And Why Is Everyone Talking About Them?

When we say “sustainable aviation fuels,” we’re actually referring to a whole family of alternatives to kerosene. This family includes SAF (Sustainable Aviation Fuel), LCAF (Low Carbon Aviation Fuel), e-fuels, hydrogen propulsion, and electric flight.

That sounds like plenty of options, right? In theory, yes. In practice, things get complicated quickly.

SAF are the front-runners. They’re produced from renewable or sustainable raw materials — think used. The most common production process today is called HEFA (Hydroprocessed Esters and Fatty Acids), and it’s currently the cheapest method available.

The big advantage? SAF are liquid and drop-in — they can be poured directly into existing aircraft fuel tanks and transported through existing infrastructure . In central Europe, for instance, jet fuel travels through the CEPS (Central Europe Pipeline System), a massive 5,300-kilometer NATO-managed fuel supply network stretching across the Czech Republic, the Netherlands, Belgium, Luxembourg, Germany, and France.

No new planes needed. No new pipelines. That’s a huge deal.

But here’s the catch. SAF can’t fully replace kerosene yet. They must be blended with traditional jet fuel, and the blend can’t exceed 50% globally. The EU imposes an even stricter limit — roughly 24% . And we’re nowhere near even that ceiling. In 2024, European SAF production barely reached *ì0.53%** of total civil aviation fuel consumption.

Let that sink in. Half a percent.

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🛫 EU ReFuelEU Mandate — SAF Blending Targets

Year	Minimum SAF Share	Status
2024 (actual)	0.53%	Current production level
2025	2%	Mandatory target — data pending
2030	6%	Mandatory target
2050	70%	Ambitious long-term goal

The **ReFuelEU regulation**, which entered into force in October 2023, lays out these milestones . It’s Europe’s legislative roadmap for weaning aviation off fossil fuels. The 2050 target of 70% sounds bold. It is bold. But looking at that 0.53% figure from 2024, the mountain ahead is enormous.

Have Planes Already Flown on 100% Sustainable Fuel?

Yes. And these flights deserve to be remembered.

In July 2022, a Braathens Regional Airlines flight completed its journey powered *entirely by SAF — the first commercial flight to do so.

Then came the headline-maker. The following year, a Virgin Atlantic Boeing 787 crossed the Atlantic from **London to New York** running on 100% sustainable fuel. The fuel mix was **88% HEFA** (from fats and oils) and 12% SAK — a synthetic kerosene derived from sugars.

A transatlantic flight. Zero fossil-derived kerosene. That’s not a lab experiment. That’s a real plane, real passengers, real ocean beneath them.

These flights proved something critical: the technology works. The bottleneck isn’t physics. It’s production scale, cost, and political will.

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Can We Turn Electricity Into Liquid Jet Fuel?

This is where the science gets genuinely exciting. There’s a process called Power-to-Liquid (PtL), and it might hold the greatest potential for scaling up SAF production in the years ahead.

Here’s how it works, step by step:

1. Water is split into hydrogen using an **electrolyzer.
2. CO₂ is captured** from the air or from industrial sources.
3. The hydrogen and CO₂ are combined and converted into liquid fuels.

The result? E-fuels — including e-kerosene, e-diesel, and e-methane.

The beauty of PtL is that, when powered entirely by renewable energy (solar, wind, hydro), the whole cycle can approach **carbon neutrality**. The CO₂ you capture is roughly what the fuel will release when burned.

The challenge? **It demands enormous amounts of energy.** And no PtL plant has gone beyond the pilot phase yet . Still, **40 large-scale European projects** are already in the pipeline . That’s not a dream — that’s an industry gearing up.

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Why Don’t We Just Build Electric or Hydrogen Planes?

We get this question a lot. If electric cars are taking over roads, why can’t electric planes take over skies?

The answer is beautifully simple: **planes fly.**

They need to lift themselves, the passengers, the luggage, *and* whatever powers them — all off the ground and keep it all airborne for hours. The energy density problem is massive. Batteries and hydrogen tanks, at the same weight as kerosene or SAF, can’t deliver the same range.

Liquid hydrogen adds another layer of difficulty. It must be stored in **cryogenic tanks** that maintain temperatures below −252°C . Those tanks are expensive, bulky, and can’t fit in aircraft wings the way current fuel tanks do . Every airport would need a completely redesigned storage and refueling system .

✈️ Aviation Fuel Technologies — At a Glance

Technology	Drop-in?	Max Capacity (today)	Commercial Timeline
SAF (HEFA)	✅ Yes	Full-size jets	Available now
E-fuels (PtL)	✅ Yes	Pilot phase	2030s (estimated)
Hydrogen	❌ No	~10 seats	Not within 10 years
Electric	❌ No	~10 seats	Not within 10 years

Today, hydrogen-powered and hybrid aircraft exist — but they carry no more than 10 passengers . Both Airbus and Boeing, the world’s two largest aircraft manufacturers, have pushed their timelines for electric and hydrogen commercial jets to **an indefinite date — certainly not within the next decade** .

NASA and several American companies continue researching both paths . We shouldn’t give up on them. But for the next 10 to 20 years, SAF and e-fuels are the only realistic game in town.

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How Much Does Sustainable Aviation Fuel Actually Cost?

Here’s where enthusiasm meets reality. Let’s talk money.

💰 Fuel Cost Comparison (per metric ton, in EUR)

Fuel Type	Price (€/ton)
Kerosene (pre-crisis)	~€816
Kerosene (post-Hormuz closure)	€1,500 – €1,600
SAF (current market average)	€2,768

SAF currently costs an average of €2,768 per metric ton . Before the recent geopolitical crisis, petroleum-based kerosene sat at around 816 per ton** . Even after the Strait of Hormuz closure drove prices up to **€1,500–1,600 per ton, SAF remains nearly double the inflated price .

And building a new SAF production plant from scratch? That requires roughly €1.8 billion in initial investment.

These numbers cool the enthusiasm of airlines, for whom fuel represents a full one-third of operating costs. Making things worse, SAF suppliers are scarce. Most airports have **no more than three fuel providers, giving those suppliers significant pricing power with little competitive pressure .

Scale can help. If production grows, economies of scale should bring prices down. But someone has to make that first massive investment — and that money has to come from somewhere.

If all the SAF plants currently under construction are completed, Europe could produce 3.2 million metric tons of SAF by 2030, which would cover the 6% mandate. Beyond that date, projections get murky.

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Are SAF Truly Green — Or Just Greenwashed?

This is the question nobody loves asking, but everyone should.

SAF don’t come from fossil fuels. That’s a win. They break the direct link to crude oil extraction, which remains the largest source of greenhouse gas emissions.

But many SAF rely on agricultural feedstocks — crops, oils, biomass. And that opens a troubling door: land consumption and deforestation.

The European Union Aviation Safety Agency (EASA)** didn’t mince words. They warned that crop-based biofuel production *”can potentially cancel any greenhouse gas savings derived from biofuels”.

Read that again. The cure could be as bad as the disease — if we’re not careful about sourcing.

To its credit, the EU has taken a strict approach. It excluded all feedstocks from food crops (human or animal) as well as palm and soy derivatives from the list of approved SAF raw materials . That’s a meaningful guardrail.

Still, there’s no full clarity yet on whether SAF deliver a net reduction in emissions during flight . The lifecycle analysis — from field to fuel tank to exhaust — is still an evolving science.

This is exactly why e-fuels matter so much. If we can produce them using renewable electricity and captured CO₂, we sidestep the agricultural trap entirely. We need both pathways — SAF and e-fuels — working in parallel.

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Could We Simply… Fly Less?

Here’s a thought that doesn’t require new technology, new factories, or billions in investment.

The most-traveled route in the European Union is Barcelona to Palma de Mallorca: an average of 20 flights per day, in just one direction . That’s roughly one flight every hour.

From Milan’s airports (including Orio al Serio), between 26 and 34 planes** depart for London every single day . More than one an hour.

Would it really ruin anyone’s plans to wait an extra hour and cut a few of those flights? Probably not.

There’s a striking image in the source article: looking at a real-time flight tracking platform, the author saw a cloud of aircraft over Europe **so dense that you couldn’t see the countries beneath** . That image stays with you.

Maybe — just maybe — we could save some kerosene simply by being a bit more patient. And by channeling electric power (from renewables, of course) into ground transportation wherever possible, we free up petroleum-based fuel for the sectors that truly can’t function without it .

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Where Do We Go from Here?

Let’s step back and look at the full picture.

The aviation industry is **not stuck**. It’s in motion — but it’s moving slowly through turbulence. SAF technology works. Historic transatlantic flights have proven it. The EU has set binding targets. Forty PtL projects are under development across Europe. Airlines, manufacturers, and governments all acknowledge that kerosene dependency is a vulnerability they need to overcome.

But the numbers are honest: **0.53% in 2024**. Costs that are **3.4 times higher** than traditional fuel. Production plants that cost **€1.8 billion** each. A sustainability story that still has gaps.

So here’s what we’re left with — a transition that demands patience, investment, honesty about trade-offs, and a willingness to rethink habits as simple as how often we fly short routes.

The good news? We already have the ingredients. We need the will to mix them in the right proportions.

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At FreeAstroScience.com, we exist to explain the world — from the farthest galaxy to the chemistry inside a jet engine — in terms anyone can grasp. We want you to stay curious. To question. To think. Because, as Goya reminded us centuries ago, **the sleep of reason breeds monsters**.

Never turn off your mind. Keep it active, keep it hungry. And come back often — we’ll always have something new waiting for you.

*— Gerd Dani, President of Free AstroScience – Science and Cultural Group*

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