“Guilt-free flying is within our reach.”

So said the government’s Grant Shapps, formerly business, formerly-formerly transport, now energy security and net zero secretary.

“Guilt-free flying”. It’s the one phrase that, more than any other, is guaranteed to make my blood boil. And people in positions of power – people who really should know better, and do – seem to love nothing more than to throw it about with reckless abandon.

In this particular instance, Mr Shapps was referring to the Conservative government’s decision to pump £113m into funding hydrogen and all-electric aviation technologies. Projects getting a cash injection include Bristol-based electric aircraft manufacturer Vertical Aerospace’s lightweight batteries, and Rolls-Royce’s plans to create a liquid hydrogen combusting jet engine.

“Guilt-free flying is within our reach, and we are backing the world-leading UK firms whose skills and ingenuity are going to make that dream a reality,” said Mr Shapps of the funding. “As the whole world moves to greener forms of aviation, there is a massive opportunity for the UK’s aerospace industry to secure clean, green jobs and growth for decades to come. Together with the companies that share our ambitions, we are determined to seize this moment.”

Transport secretary Mark Harper added: “The Jet Zero Council is helping to define the future of flying – one that’s more optimistic about the sector’s environmental impact while putting UK innovation at the forefront of international aviation.”

And fair play: it is, in some respects, an exciting time for the development of carbon neutral air travel technologies in the UK. Just last month, a British aerospace company completed a groundbreaking test flight of the world’s largest aircraft powered by a hydrogen-electric engine. ZeroAvia successfully flew a 19-seater hydrogen electric-powered Dornier 228 testbed aircraft in the UK town of Kemble on 19 January; it was the largest plane powered by a hydrogen-electric engine to ever complete a test flight. Taking off from the company’s R&D facility at Cotswold Airport in Gloucestershire, the plane was airborne for 10 minutes.

It’s part of a process which the company hopes will see it deliver commercial hydro-electric flights by 2025. “This is only the beginning,” said Val Miftakhov, founder and CEO of ZeroAvia. “We are building the future of sustainable, zero climate impact aviation. Our approach is the best solution to accelerate clean aviation at scale.”

The landmark test flight was part of the HyFlyer II project, a major R&D programme backed by the UK government as part of its ambitions to develop zero-emission flights. And guess what our old friend Mr Shapps said of it at the time? Fingers on buzzers...

“The flight is a hugely exciting vision of the future – guilt-free flying and a big step forward for zero-emission air travel.”

Guilt-free flying.

So, why is it that I take such umbrage at this phrase? Doesn’t he have a point – after all, won’t hydrogen-powered flights allow us to achieve zero-carbon air travel?

The problem is the numbers involved – and the utter lack of scalability. ZeroAvia’s ground-breaking flight, while impressive, was 10 minutes long, with a plane that can carry 19 people (though there weren’t actually 19 passengers onboard). In 2022, passengers passing through the UK’s biggest airports – Heathrow, Gatwick, Manchester and Stansted – hit 61.6, 32.8, 23.4 and 23.3 million respectively, totalling 141.1 million. And this was about a fifth down from 2019 as airports struggled to ramp up flight schedules following the pandemic. The 2023 numbers are likely to far outstrip last year’s figures.

Looking at those numbers, it is very apparent that a successful 19-seater test flight, along with all the other exciting but small-scale innovations we’re seeing, isn’t going to come close to solving the UK’s aviation problem. The issue with all the new aviation tech – from hydrogen to electric planes and SAFs (sustainable aviation fuel) – is that, aside from cost (all of these are far pricier than cheap, tax-free kerosene); infrastructure hurdles (such as equipping airports to be able to store hydrogen and refuel planes with it); physics limitation (for example, the size and weight of battery needed to power a plane means it will only be useable for small aircraft doing very short hops)... well, aside from all that, there is no feasible plan to be able to scale any or all of it up to meet current aviation demand.

Even with SAFs, which are already problematic (they don’t, for example, reduce the amount of emissions produced in-flight), there is not the capacity to increase the amount being produced to anywhere near what’s needed. According to a report from the European Union Aviation Safety Agency (EASA), “with the introduction of a SAF blending mandate at EU level, demand for aviation fuel at EU airports would amount to around 46 million tonnes in 2030. In order to reach 5 per cent of SAF by 2030 for all flights departing from EU airports, approximately 2.3 million tonnes of SAF would be required. Currently, the maximum potential SAF production capacity in the EU is estimated at around 0.24 million tonnes, i.e. only 10 per cent of the amount of SAF required to meet the proposed mandate by 2030.”

So, it’s already going to be ambitious to reach an EU mandate of 5 per cent of all air transport fuel being SAF by 2030. And that still leaves a whopping 95 per cent of the fuel used as just regular, emissions-heavy kerosene.

It’s why the concept of “guilt-free flying” – and the government’s tenuous aviation plan entitled “Jet Zero” – is more than just wishful thinking. It’s dangerously misleading. There is no current pathway to carbon neutral flying that doesn’t include a significant reduction in the number of planes in the sky. In ignoring this inconvenient truth, the government has proven that, once again, its head is firmly in the clouds.

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