There isn’t enough ‘sustainable’ aviation fuel to make a dent in our emissions – and there won’t be for years

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Most of this fuel is currently made from used cooking oil. Scharfsinn / shutterstock

Ben Purvis, University of Sheffield

The UK chancellor, Rachel Reeves, has described so-called sustainable aviation fuel (SAF) as a “game changer”. As she announced government support for a series of airport expansions, she said that the fuel “can reduce carbon emissions from flying by 70%”.

This number is misleading. Optimistic estimates do suggest that fully replacing fossil jet fuel with its sustainable alternative could lead to total savings of around 70%. But it will be hard to produce enough SAF to make a difference on that sort of scale. Even if the UK meets its ambitious targets, an annual saving of 7% by 2030 is more plausible.

SAF is synthetic liquid fuel derived from something other than fossil fuels. These inputs have to be processed into a liquid that can be burned safely while also storing a lot of energy for its weight, since minimising weight is crucial. This is why long-haul electric battery-powered planes are unlikely to take off any time soon.

The UK classifies three major pathways for creating sustainable aviation fuel. It can be derived from oils or fats, including used cooking oil or tallow. It can come from other sorts of material, such as municipal solid waste, agricultural residues, or sewage. Or it can be made from hydrogen and captured carbon using renewable electricity.

SAF can also be produced from bioenergy crops, and products such as palm oil. However the UK won’t certify it as sustainable, due to concerns about land use and impacts on wildlife.

Emissions that would have occurred anyway

Burning SAF actually emits a similar amount of CO₂ to fossil jet fuel. Instead, most savings come from how we account for the waste and renewable energy that is used to produce it.

landfill
Waste emits greenhouse gases anyway, sustainable fuel supporters argue. So why not have those emissions do something useful, like power a plane? Jenya Smyk/shutterstock

SAF fundamentally relies on assumptions that if waste or energy crops were not used to make this fuel, they would be incinerated, would degrade, or would in some way release their embodied carbon anyway. In the case of fuel derived from renewable energy and captured carbon, it assumes that carbon came from the atmosphere in the first place. This allows these emissions to be deducted from the total impact of SAF, leading to lower emissions than conventional aviation fuel.

Is sustainable aviation fuel even sustainable?

Estimates of how much greenhouse gas SAF could cut vary greatly due to the many different ways it can be produced, and the complexities of accounting for emissions across the entire life cycle from waste, to fuel production, to plane engine. A 2023 review by the Royal Society illustrates this nicely. It found SAF could at best produce effectively negative emissions (a 111% reduction), while at worst it could be more carbon intensive than fossil kerosene jet fuel (a 69% increase).

While policy incentives are likely to encourage increased production, there remain serious concerns that will need to be addressed before SAF can become a serious competitor for conventional jet fuel. There are hard limits to the amount of used cooking oil available for instance, and the use of other feedstocks is still in its infancy.

Meanwhile any renewable energy used to make the fuel will have to compete with growing demand from electric vehicles, AI data centres and more. And there are big worries the industry simply won’t be profitable enough to attract initial capital investment, let alone take on its well-established rival.

UK SAF production

Coming into effect in January, the UK’s SAF mandate sets legal obligations for aviation fuel suppliers in the UK to progressively increase proportions of sustainable fuel, from 2% of total jet fuel in 2025 to 10% in 2030, and 22% in 2040.

This is one of a growing number of commitments globally, including RefuelEU, and the US SAF grand challenge, which seek to increase demand and encourage more investment in production.

As of 2023, 97% of the UK’s supply is derived from used cooking oil, with the rest from food waste. Only 8% of this cooking oil is sourced from the UK, with most being imported from China and Malaysia. The UK also comprises 16% of the global SAF market, despite representing only 1% of total passengers.

Currently, the only commercial producer of SAF in the UK is the Phillips 66 Humber Refinery which processes used cooking oil. The previous government allocated £135 million of funding to nine projects, aiming to have five plants under construction by 2025. Despite several projects selecting sites, at the time of writing none appear to be under construction.

In an industry with razor-thin profit margins, SAF remains considerably more expensive than conventional aviation fuel. With potential producers filing for bankruptcy and companies including Shell pulling out due to profitability concerns, the market is looking rocky.

A 7% saving is more plausible

Let us assume that Rachel Reeves’ 70% saving is deliverable if fossil jet fuel was fully replaced with SAF. That’s optimistic in itself, but not beyond the realms of possibility.

Getting hold of that much sustainable fuel is less plausible, however – the total demand for jet fuel in the UK is more than ten times the current global production of SAF. But let’s assume that the rocky global market can deliver the UK’s ambitious demand of 10% SAF use by 2030.

Reeves’ figure then becomes an optimistic value of 7% savings across the UK industry. If we then correct for anticipated growth of passenger numbers, assuming plans for airport expansion, those savings are likely to vanish.

While SAF has a role to play in decarbonisation, growth sits in clear opposition to its impacts and potential. If the UK has any hope of meeting its climate targets, it should instead be seeking alternatives to flying where possible.


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Ben Purvis, Research Associate, Sustainability Assessment, University of Sheffield

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Continue ReadingThere isn’t enough ‘sustainable’ aviation fuel to make a dent in our emissions – and there won’t be for years

Reeves’s Heathrow third runway report was commissioned by London airport

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https://www.theguardian.com/environment/2025/feb/01/reevess-heathrow-third-runway-report-was-commissioned-by-london-airport

The chancellor is under fire after a study cited as evidence for expanding the terminal to boost the UK’s economic growth was ordered by Heathrow itself

Rachel Reeves was facing criticism on Saturday night as it was confirmed that a report she cited as evidence that a third ­runway at Heathrow would boost the UK economy was commissioned by the airport itself.

Experts and green groups also challenged Reeves’s view that advances in the production of ­sustainable aviation fuel (SAF) had been a “gamechanger” that would substantially limit the environmental damage of flying, ­saying the claims were overblown and did not stand up to scrutiny.

Alex Chapman, senior economist at the NEF, said: “It is very concerning that the chancellor appears to be basing her support for Heathrow expansion on a figure from a report commissioned by Heathrow airport.

“Even more worrying is the fact that the methodology they have applied is one that the Department for Transport has previously decided is not fit for purpose, and that the report uses forecast data supplied by the airport itself.

“Heathrow expansion represents a major threat to the UK’s climate goals and flies in the face of scientific advice. To ensure that the claimed economic benefits are concrete, assessments should be carried out by independent government economists following best-practice methodology.

“NEF’s analysis has identified a wide range of weaknesses in the economic case, which have emerged since it was last fully appraised in 2015. Not least, the decline of business air travel, the surge in outbound leisure travel and the negative impacts on wider regions of the UK – all of which erode the potential growth benefit.”

Analysis by climate crisis website Carbon Brief suggests that, using the government’s own figures, SAF will barely cut emissions by 2040, and any reduction will be wiped out by rising flight numbers.

https://www.theguardian.com/environment/2025/feb/01/reevess-heathrow-third-runway-report-was-commissioned-by-london-airport

Continue ReadingReeves’s Heathrow third runway report was commissioned by London airport

Why the world’s first flight powered entirely by sustainable aviation fuel is a green mirage

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A Boeing 787 Dreamliner landing at Heathrow international airport in London.
Fasttailwind/Shutterstock

Gareth Dale, Brunel University London and Josh Moos, Leeds Beckett University

A Boeing 787 Dreamliner is set to take off from Heathrow on November 28 and head for JFK airport in New York, powered by so-called sustainable aviation fuel (SAF). According to its operator, Virgin Atlantic, the world’s “first 100% SAF flight” will mark “a historic moment in aviation’s roadmap to decarbonisation”.

It is proof of concept, we are led to believe, of the dawn of “guilt-free” flying. Unfortunately, we have been here before, and the results last time were anything but green.

Based on our research into how wealth and power shape the environment, we argue that continued growth of the aviation sector, as with the economy in general, is incompatible with preventing runaway climate change. The technology currently being developed by the aviation industry has zero chance of changing that. And the fuels being used in Virgin’s latest experiment are not significantly more sustainable than those in its previous attempt.

Virgin’s sustainability initiative dates back to the 2000s, when British business magnate Richard Branson was at the helm. In 2008, to some fanfare, a Virgin aircraft flew from London to Amsterdam using a fuel derived in part from palm oil and coconuts. Technically, the mission was a success, but the sustainability claims were laughable.

To have fuelled that short hop with 100% coconut oil would have consumed 3 million coconuts. The entire global crop would supply Heathrow for only a few weeks — and it is one of 18,000 commercial airports worldwide. Following this stunt, Virgin gave up on coconut oil.

Virgin’s latest flight is simply a repeat of 2008. It’s a smoke-and-mirrors exercise to convince governments that SAF will enable aviation to continue its relentless growth on a sustainable basis – and in this, it is succeeding.

Even waste products aren’t sustainable

Virgin’s defence rests on the claim that its new SAF no longer comes exclusively from crops. It is blended with waste products. One of the main suppliers for Virgin’s transatlantic flight is Virent, an organisation based in Wisconsin. Virent makes SAF from conventional sugars such as corn, mixed with wood, agricultural waste and used cooking oil.

As with coconuts, any crop grown for fuel competes with foodstuffs and pushes the agricultural frontier further into forests and peatlands, with large releases of carbon.

But what of the waste products? Surely reusing cooking oils offers a sustainable solution? Unfortunately, in a notoriously unregulated market, it seems not.

Another of Virgin’s suppliers, Neste, collects cooking oils from sources worldwide, including McDonald’s restaurants in the Netherlands and food processing plants in California, Oregon and Washington. The US Department of Agriculture alleges that some trade in SAF feedstocks – including from Indonesia to Neste’s refinery in Singapore – may be “fraudulent”.

Neste has denied the claim. But, even if its used cooking oil is entirely legitimate, there is still an allegation that palm oil from plantations responsible for tropical deforestation is being marketed as used cooking oil.

Virgin Atlantic maintains that the SAF it uses is made entirely from used cooking oil. However, if the aviation industry bets big on used cooking oil, it is feared it will turbocharge tropical logging and the extermination of the orangutan and countless other endangered species.

Orangutan in the rainforest on Borneo island with trees and palms behind.
More tropical logging would threaten the orangutan and countless other endangered species.
Michail_Vorobyev/Shutterstock

The real kicker is that even if all used cooking oils were traceable and sustainably sourced, they are not scalable. The US collects around 600,000 tonnes of used cooking oil each year. If every last drop were diverted to SAFs, it would meet at most 1% of America’s current aviation demand.

Capturing the White House

The problems of scalability, the competition of agricultural inputs with foodstuffs, forests and wildlife, and the carbon emissions that result from land use change are just three of the shortcomings that ensure SAFs will not be the magic bullet that the aviation industry would have us believe. Despite this, SAF fever has won over the White House.

The Inflation Reduction Act set targets for SAF production at 3 billion gallons by 2030 and 35 billion by 2050. These targets are fantasies. But, to the extent that they are approached, they will only add to the pressure on food prices and wildlife.

That SAF is being touted so zealously attests to the shortage of alternative technologies. Battery-powered planes are viable but only as short-haul “flying taxis” that compete with ground transport. The other panacea, hydrogen, confronts colossal technological and infrastructural barriers, problems of scalability, competing uses, and environmental concerns.

Tinkering with aircraft technology, such as engine size or wing shape has also faced diminishing returns. Efficiency improvements lag far behind the sector’s growth, which is why aviation emissions are still soaring.

Where do we go from here?

Ahead of the 2008 coconut-fuelled flight, Virgin’s chief executive Steve Ridgway explained its logic. He said the aviation industry needs “to be seen to be doing something”. Fifteen years on and the playbook remains the same.

The Virgin Atlantic SAF flight promises to rescue the airline from the threat of climate change, allowing them and their passengers to “keep calm and carry on”. In buying into this fantasy, governments give themselves an excuse to avoid taking climate breakdown seriously – an emergency that requires radical action if the planet is to remain habitable for humans.

There is the potential to create a good life for all within planetary boundaries. But getting there requires clipping the wings of the aviation industry.

This would begin, for short-haul, with ground-based alternatives. Within the US, many flights could be swiftly replaced by coach travel, and over a quarter of flights between EU destinations could be replaced by high-speed rail. For long-haul, the first step is demand management, which will expedite the use of virtual conferencing, marine transportation and other alternatives.

Modern high-speed train driving past a station in a city.
Many flights could be replaced by high-speed rail.
aappp/Shutterstock

Developing alternatives would be practical, efficient and create jobs. And now is a good time to begin. Americans have been “falling out of love with flying” in recent years, in part due to large numbers of flight cancellations following bad weather, which is only likely to increase with climate breakdown.

As the weather chaos worsens, the aviation industry will find it harder to shrug off its responsibility through PR stunts and greenwashed gimmickry.

In response to this article, a Virgin Atlantic spokesperson said that the organisation is committed to achieving net zero by 2050, and has set interim targets, including 10% SAF by 2030. It sees SAF as a mid-term solution for decarbonising aviation, and that Flight100 aims to demonstrate the safe use of 100% SAF within existing infrastructure. Virgin Atlantic referred to a Sustainable Aviation report, which indicates that there is sufficient feedstock to meet the government’s 2030 target without environmental impact or competition with crop production.


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Gareth Dale, Reader in Political Economy, Brunel University London and Josh Moos, Lecturer in Economics and Politics, Leeds Beckett University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Continue ReadingWhy the world’s first flight powered entirely by sustainable aviation fuel is a green mirage

COP26: CLIMATE ACTIVISTS TO TARGET 10 UK AIRPORTS THIS WEEKEND TO PROTEST EXPANSION

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https://www.independent.co.uk/travel/news-and-advice/cop26-airport-expansion-protests-uk-b1950499.html

Climate activists will target 10 UK airports this weekend to protest proposed expansion.

Campaigners are planning to protest at Bristol, Doncaster-Sheffield, Gatwick, Glasgow, Leeds-Bradford, London-City, Luton, Liverpool, Manchester and Southampton airports from 11am on Saturday.

[Hypocritical P]oliticians have consistently refused to endorse any reduction in flights, or any restraint on further aviation growth.

Speaking ahead of a UN climate conference earlier this year, MP Rachel Maclean – the minister in charge of government policy on the future of transport and decarbonisation – said flying was one of the things that “make life worth living” and that the government would not place any restrictions on the aviation industry.

Airlines are increasingly committing to becoming “greener” by using technology such as Sustainable Aviation Fuels (SAF) – however, these will account for 10 per cent of aviation fuel, at most, by 2030, and SAFs emit at least as much CO2 inflight as conventional kerosene.

Continue ReadingCOP26: CLIMATE ACTIVISTS TO TARGET 10 UK AIRPORTS THIS WEEKEND TO PROTEST EXPANSION