The temperature of the runway hit 50C at the Farnborough airshow this week. Officials checked for melting asphalt between the aerospace industry showing off its wares, with flights by passenger jets including the Boeing 777X and Airbus A350, assorted military aircraft and flypasts by the Red Arrows display team.
The heat on Monday was yet another reminder, if one were needed, of the urgency of decarbonising aviation, responsible for about 3% of global emissions. The threat of climate crisis has taken the shine off an industry that was once the height of glamour, and zero-emissions flight presents a technical challenge far greater than decarbonising most other parts of the economy.
Air passenger numbers are roaring back after pandemic lockdowns, even on slower-recovering long-haul routes, but aerospace executives are increasingly keen to emphasise their investments in technologies that will deliver zero-carbon flight, while governments are belatedly turning their attention to aviation emissions.
Boris Johnson confused executives with a rambling opening speech – “an audition for his future career on the after-dinner circuit”, one senior industry insider noted wryly – but the UK government also used the show to pledge that 2019 would be the peak year for aviation emissions.
The key measure – beyond an aspiration to have zero-emissions flights by 2030 in some parts of the UK – was a mandate that 10% of all jet fuel used in the UK is so-called “sustainable” aviation fuel (SAF) by 2030, double the EU’s target. This will come about thanks to an ambition to have at least five commercial-scale SAF plants under construction in the UK by 2025.
Environmental groups said the strategy lacked a focus on reducing air traffic – a dirty word at an industry event known for its barrage of orders of new jets that produce more than 800,000 tonnes of carbon dioxide equivalent over their lifetimes.
Alethea Warrington, a campaigner at the climate charity Possible, said: “Heavily relying on undeveloped, extremely expensive or unworkable technologies, the strategy crucially fails by leaving out a policy to fairly reduce the demand for flights such as a frequent flyer levy.”
Asked about the change in policy that could accompany a change in prime minister, Warren East, the Rolls-Royce chief executive, said he hoped the UK government remained committed to reducing aviation emissions.
“The energy transition and the need for zero-carbon power transcends any change in government,” he said.
Some suppliers to Airbus and Boeing face less of an existential risk than engine makers. Collins announced it is developing high-voltage, high-power wiring that could be used in hybrid engines that combine electricity and fossil fuels. The US company’s facility in Solihull in the West Midlands has also produced a working prototype electric motor for the Airlander airship, which will be fully electric by 2030.
Henry Brooks, president of power and controls at Collins, said hybrid propulsion could eventually save up to 30% of a passenger jet’s emissions. “The hybrid electric part is very real,” he said.
For net zero flight, however, the message from Farnborough was that the industry is pinning its hopes firstly on SAF and then on unproven hydrogen technologies.
SAF can be made from plants or clever chemistry. Yet many analysts doubt it will be able to live up to its name without using vast quantities of arable land for the feedstock or vast amounts of energy in chemical reactions.
East said he sees “multiple decades” of demand for SAF, after a first net zero flight in 2023.
The second big hope of the industry is hydrogen. Hydrogen is an attractive fuel because water, rather than carbon dioxide, is the only output when it oxidises.
EasyJet and Rolls-Royce announced at the show they would jointly invest in hydrogen gas turbine engines, while Airbus this week said it would study the effects of steam contrails in the atmosphere produced from using hydrogen. Airbus has already announced work on hydrogen propulsion with CFM, an engine joint venture owned by General Electric and Safran, in marked contrast to Boeing whose hydrogen efforts have been limited to testing a storage tank.
“Hydrogen is being built up as a bit of a panacea,” said East, but he expects it will take between 15 and 25 years before a twin-aisle, widebody jet can run purely on the gas.
Even then, it could still be relying on combustion rather than generating electric power onboard with fuel cells. A combustion scenario could give engine manufacturers cover to keep making profitable but polluting gas turbines (theoretically capable of burning either kerosene or hydrogen) for longer.
Val Miftakhov, chief executive of hydrogen fuel cell plane startup ZeroAvia, said his aim is “true zero” flight using hydrogen produced from renewable power – not net zero, which relies on re-emitting carbon previously captured from the atmosphere.
The company is aiming to certify a 19-seater aircraft by 2024, and a 90-seater by 2028. He is optimistic that “20 to 30 years from now we will have technology that covers all aircraft”, but adds the caveat that “I can’t tell you how exactly”.
Battery electric flight on passenger jets capable of carrying well over 100 people is further off. East said it would be “probably in my lifetime in quite a small plane – but I will be very old”. A battery-powered transatlantic flight is more likely to be seen only by his grandchildren, he added.
In the meantime, the industry is hedging its bets on how to fly with zero emissions. But the order bonanza for fossil fuel jets suggests that, for all the talk at Farnborough of emissions-cutting technologies, the aviation industry is counting on the jet fuel age to continue for decades.
