Here is a question for all you busy executives, deal makers and time-starved travellers. If you could save three hours flying from London to New York on a supersonic jet, but knew your journey would generate two to eight times the carbon of a flight on a conventional aircraft, would you do it?
Two weeks ago, American Airlines put down an undisclosed deposit for 20 supersonic aircraft being developed by Colorado start-up Boom. Blake Scholl, Boom’s founder, believes there are enough of you out there to fill “hundreds if not thousands of these aeroplanes”. I am not so sure.
Twenty years ago, when Concorde was guzzling twice the fuel of a 747 jumbo to carry a quarter of the passengers, companies did not have to measure their carbon footprints. Today, they are under pressure from investors, regulators and customers to reduce the climate impact of doing business.
Even assuming that Boom overcomes the noise problem, supersonic travel will be one of the least green and most expensive options for air passengers.
Dan Rutherford, aviation programme director of the International Council on Clean Transportation, calculated that flying on a Boom-like supersonic jet powered by conventional jet fuel would emit eight times the carbon of an economy-class passenger on a subsonic plane, or twice the carbon attributed to someone in business class.
Boom says its Overture will fly on 100 per cent sustainable aviation fuels (SAF) — although it does not yet have an engine. A very clean SAF would enable it to generate up to 24 per cent fewer carbon emissions per seat km than an aircraft flying on conventional fuel, according to a study by the ICCT and Massachusetts Institute of Technology. But that research also concludes that supersonic’s non-carbon climate impact, from agents such as nitrogen oxide and water vapour, could be significantly worse because of the higher altitude at which these aircraft fly.
Moreover, if Overture can fly on SAF, so can other aircraft. All conventional jet engines are capable of flying on 100 per cent sustainable fuel, with a few minor tweaks. It is regulators that have restricted use to 50 per cent.
Boom’s claim to sustainability also presumes that there will be enough reasonably priced green fuel around to power the aircraft, which is due to fly in 2029. But that is far from certain. Iata, the airline industry trade body, estimates that aviation uses roughly 450bn litres of fuel a year. Current investment plans suggest production of only 5bn SAF by 2025, Iata says. It notes that effective government incentives could take this to 30bn a year by 2030 — still far short of the industry’s needs. That shortfall means that SAF is likely to be more expensive than jet fuel for some time.
Conventional fuel accounts for roughly 30 per cent of an airline’s operating costs. So why would carriers use a more costly option for a supersonic aircraft that will consume significantly more fuel than a modern subsonic aircraft? My guess is that they won’t. Even if a carrier did go down that path, tickets would have to be so prohibitively priced, that only a select few could afford them.
High fuel costs and the small size of a very niche market contributed to the grounding of Concorde in 2003, according to John Strickland, an aviation consultant who was involved in network planning for the British Airways Concorde. “We could only make it work on the London to New York route by getting premium traffic,” he said. “It was a very small number of people doing repeat business,” such as business executives, dealmakers and “a few celebrities”.
Since then, the economics of supersonic travel have not obviously changed — but much else has. For a start, the business travel outlook is not what it was when Boom was launched in 2014, thanks to the rise of video conferencing post-Covid. And those passengers who once prized time savings over cost now have to factor in the environmental impact of their journeys.
“Clients will say ‘we don’t want you using it . . . It’s bad for our carbon footprint’,” said one leading mergers and acquisitions lawyer who often used Concorde. “I can see major investment banks simply saying their bankers will not use the aircraft.”
Flying faster than the speed of sound is a thrilling concept. But business travellers will have to weigh up whether saving a few hours’ journey time is really worth the damage that could be done to their reputations, and to the environment.
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