‘Sustainable’ aviation fuel and other myths about green airport expansion debunked
Environmentalists and locals have resisted a third runway at London’s Heathrow, Europe’s busiest airport, for more than two decades. Today, their efforts took a major setback.
The UK government has announced it will give the green light to airport expansion. This is not guaranteed to increase growth in the national economy as Chancellor Rachel Reeves hopes. More flights and more emissions are certain, however, at a time when experts are practically screaming at governments to rein them in.
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“No airport expansions should proceed” without a UK-wide plan to annually assess and control the sector’s climate impact said the government’s watchdog, the Climate Change Committee, in 2023. Aeroplanes are 8% of UK emissions and 2% of the world’s, but they also release gases that seed heat-trapping clouds in the upper atmosphere, which triples air travel’s greenhouse effect.
While the government’s own advisers have effectively ruled out new runways for the sake of net zero, airport and airline bosses play a different tune. So what does the sector propose to manage its own pollution?
Not enough cooking oil to save us
Aviation is a notoriously difficult sector to decarbonise says Richard Sulley, a senior research fellow in sustainability policy at the University of Sheffield: “If electric or hydrogen-powered planes are possible, it won’t be for many years yet.”
To justify air travel emissions ballooning in the meantime, the aviation sector has promised a mix of “supply-side” measures, like replacing kerosene with so-called “sustainable aviation fuel” (SAF), which Reeves described as “a game changer”, and making planes lighter and more fuel-efficient.
Efficiency, in this context, is a slippery path to decarbonisation. When a high-emitting activity is reformed so that it consumes less energy, the efficiency savings are generally eclipsed by the increasing demand it drives.
“Indeed, the sector’s own plans for growth will outstrip efforts to decarbonise through synthetic fuel, delivering a neutral effect at best,” Sulley says.
“Demand-side” measures like fewer flights, taxes on frequent flying and domestic flight bans (see France) could cut emissions, he notes, but are seldom mentioned.
The UK has set a target for airline fuel to be 10% SAF by 2030. So far we’re at 1.2% – and Sulley reports that the industry has not said how it will scale up in time.
Even if airlines start taking their commitment to SAF seriously very soon, it’s a dubious solution to aviation’s climate impact according to political economists Gareth Dale (Brunel University) and Josh Moos (Leeds Beckett University).
Earlier SAF test flights burned coconut oil – 3 million coconuts to power a journey from London to Amsterdam, as Dale and Moos calculate it. At that rate, they argue Heathrow would exhaust the world’s entire crop in a few weeks (there are 18,000 commercial airports worldwide).
Modern SAF is blended with waste products from farms and kitchens. But the pair argue that the market for used cooking oil is “notoriously unregulated”. SAF may in fact be relabelled palm oil from plantations that are erasing orangutan habitat in the tropics. Again, Dale and Moos argue there is not enough used cooking oil to meet existing, let alone future, demand.
Transport for the rich, by the rich
At least the hype around SAF addresses the main problem, albeit misleadingly. Policy experts David Howarth (University of Essex) and Steven Griggs (De Montfort University) marvel at how often “carbon-neutral airports” in aviation sustainability strategies simply mean terminals powered by renewable energy.
“A terminal’s heating or lighting is, of course, largely irrelevant when its core business is as emissions-intensive as flying,” says Sulley.
Unfortunately for Rachel Reeves, a 2023 report by the New Economics Foundation found that any economic benefits of airport expansion will be largely confined to the airports themselves. Meanwhile, a wealthy subset of UK society can be expected to capture the biggest share of any new flight capacity. Each year, around half of British residents do not fly at all, Sulley points out.
At the stratospheric heights of that subset are the private jet passengers who are served by “more or less dedicated airports” that are more obscure to the general public, says Raymond Woessner, a geographer at Sorbonne Université. A study published in November found that emissions from these flights rose by 46% between 2019 and 2023. The lead author described wealthy passengers using jets “like taxis”.
“Discretion and anonymity” is what one airport nestled in the Oxfordshire countryside promises for “routine celebrity, head of state and royal visits”. Without state direction or regulation, it is these people who are setting the agenda for air travel.
Woessner notes that the world’s richest man, Elon Musk, successfully lobbied to derail a high-speed rail project in California in 2013. Instead of an option that has shown its ability to cut flight demand, the US will be offered intercontinental rocket travel.
Musk’s company SpaceX says that rockets could ferry passengers between New York and Shanghai in under an hour. Rockets would burn “vastly more fuel per trip than conventional aircraft”, says aerospace engineer Angadh Nanjangud of Queen Mary University of London, but this might “drive critical research into carbon-neutral” methane-based rocket fuel.
It would not be the first time an industry seeking to grow has used an as yet fantastical fuel to justify more carbon in Earth’s atmosphere.
“There is the potential to create a good life for all within planetary boundaries,” say Dale and Moos.
“But getting there requires clipping the wings of the aviation industry.”
Jack Marley, Environment + Energy Editor, The Conversation
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