The push to develop hydrogen-powered planes was once a key part of the aviation industry’s bid to eliminate carbon emissions. But in the last few weeks, it has fallen suddenly and dramatically out of favour.
First, European airlines and manufacturers drastically downgraded their target for the contribution of hydrogen to their goal of reaching net zero by 2050.
Then Airbus, the world’s biggest plane maker, put the industry’s most advanced programme for developing a hydrogen-powered passenger aircraft on hold.
Boeing, always a comparative sceptic, has meanwhile confirmed that it sees little or no role for hydrogen in decarbonising its own jets for decades at least.
The decline in hydrogen’s fortunes represents a potential setback for the UK, where British companies and the Government have invested hundreds of millions of pounds in the technology.
It also leaves the European aviation industry facing a bill of more than €1 trillion (£830bn) to decarbonise by the middle of the century, a total it will struggle to fund alone.
Hydrogen planes “have almost vanished from the road map”, says Carlos López de la Osa, of Transport & Environment (T&E), which promotes sustainable flying.
Electric airliners are regarded as a little more than a pipe dream by many experts because of the excessive weight and low energy density of batteries, while the credibility of sustainable aviation fuel (SAF) is in doubt.
Climate campaigners question its carbon-reduction credentials and the gap between production volumes and industry requirements widens every year.
“Aviation needs to get its act together,” says López de la Osa. “It’s a hard industry to decarbonise and it will be expensive and difficult, but with the progress made in the automotive and power sectors it is going to be really in the spotlight.
“The worrying thing is that hydrogen has failed to take off, SAF is also struggling and there has been no great progress in other technical solutions.”
Hydrogen has been seen as a great source of hope for decarbonising aviation because of its abundance, clean burn and compatibility with current engines. Capable of being harvested from water, it can be put into ordinary jet turbines and releases only water vapour as a by-product when burned.
Europe’s aviation industry predicted hydrogen would power a fifth of all plane journeys by 2050 under plans drawn up in 2021 to reach net zero by the middle of the century.
However, despite its significant promise, hydrogen has proved far harder to harness commercially than first hoped.
For use in a plane it must be cooled to -250C to turn it into a liquid and then stored at that temperature on board. Making this work for commercial aviation has proved fiendishly difficult.
Then there is the problem of production. Producing hydrogen at the scale needed by the aviation industry requires huge investment in electrolysis, liquefaction plants, gas pipeline networks and liquid hydrogen distribution, storage and refuelling infrastructure.
To create truly green hydrogen, it must also be synthesised using clean electricity generated through renewables – another challenge.
Indications that something was amiss with Airbus’s hydrogen strategy first emerged in mid-January, when Guillaume Faury, the chief executive, played down prospects for the technology.
Asked whether the industry would be dependent on SAF beyond 2050, Faury replied: “Yes, of course, way beyond.”
He added: “Hydrogen is an energy that will become sizeable and meaningful in the second half of the century, not in the first half.
“We spent really a lot of money, time and effort and good engineers on hydrogen because we believe in it. But it is not going to be the solution for the next 20 years.”
This month, the French FO union revealed that Airbus had scrapped plans to develop a smaller hydrogen-powered aircraft with fewer than 100 seats by 2035.
The union said the target date for the plane had been pushed back by five or 10 years, with the budget for the project, known as Zeroe, slashed by 25pc. (The initiative was set up to explore three concept planes powered by hydrogen combustion and another reliant on hydrogen fuel cells.)
Airbus responded by confirming that the aircraft’s planned date to enter service had been delayed beyond 2035, amid slow progress in developing the technology and mounting concerns about the supply of the green hydrogen required to actually eliminate CO2 emissions.
It added that developing a hydrogen ecosystem spanning production, distribution, infrastructure and the required regulatory frameworks, represented a “huge challenge.”
Much of the work on the Airbus project has taken place at its Zeroe development centre in Filton, Gloucestershire, where research has focused on storage and fuel systems for cryogenically cooled hydrogen.
Airbus didn’t say what specific technological issues contributed to the Zeroe delay. But in his January update Faury said that the need to cool and store hydrogen in a liquid state at -250C, and modify an aircraft to accommodate that, continued to present a challenge.
Slow progress in developing the technology and concerns over the supply of the green hydrogen prompted the delay to the Zeroe project - Airbus/AFP via Getty Images
He said: “The architecture of a hydrogen plane is very different from the architecture of a SAF aircraft. If you want to carry enough hydrogen to have a decent range it has to be liquid.
“Even then it takes up more volume than kerosene and to keep it liquid you need to have it in a cryogenic tank and it cannot be distributed in the wings. So you have to build the architecture of the plane around the fact that it is going to be hydrogen.”
Airbus had been focused on bringing a smaller hydrogen plane to market for regional travel. However, Zeroe also included a “blended wing” design seen as a possible solution for fuel-storage issues and capable of carrying a notional 200 people.
A source close to Boeing said Airbus’s bid to have a hydrogen plane ready for the 2030s “ran contrary to the laws of physics”.
The source said: “Boeing has 15 years of experience with hydrogen and the challenges of cryogenic storage and the very large volumes needed. Even from the get go it was apparent that the timeline was always going to be much longer than they suggested.”
As Airbus’s hopes have faded, the European aviation industry has downgraded its hopes for the fuel. It has issued a new roadmap for achieving net zero that effectively reduced hydrogen to a footnote.
The update, commissioned by trade bodies representing European airlines, airports, aerospace manufacturers and air traffic controllers, said hydrogen planes would now be responsible for just 6pc of the required CO2 reduction, down from the 20pc forecast in 2021.
Describing the findings as a “reality check”, it said they were based on “the lower anticipated market share of hydrogen-powered aircraft” and “the later entry into service of the hydrogen-powered single-aisle”.
The study still anticipates that hydrogen planes will debut by 2040, but cautions that should their introduction recede further, “only a marginal contribution by 2050 remains”.
As well as downgrading the role of hydrogen, the European aviation industry has radically scaled up its estimated cost of reaching net zero. It has jumped by 50pc to €1.3 trillion as a result of the scarcity and inflated price of SAF, something the industry couldn’t hope to fund from its own resources, the report says.
When the new net zero roadmap was published, Airbus initially reiterated the 2035 target date for Zeroe, “only to admit that it was dropping it three days later”, López de la Osa says. “They must have known for some time and you now wonder even more if we can trust the industry to decarbonise.”
It is understood that Airbus sought to reassure members of the Hydrogen in Aviation (HIA) alliance of its commitment to the technology at a meeting last week.
HIA brings together UK players including Rolls-Royce and easyJet, which have been collaborating to develop a hydrogen-burning engine that is set to commence testing at Nasa facilities in Mississippi this summer.
A spokesman for easyJet said the airline had already pushed back its own expectations for a hydrogen plane to 2040 but remained committed to advancing the technology.
Another HIA member, ZeroAvia, has been working on fuel cells that turn hydrogen into electricity through a chemical reaction. The energy produced is limited, however, with the company’s initial ZA600 engine designed to power a plane with no more than 20 seats.
GKN Aerospace, which has been working on fuel cells, hydrogen propulsion and liquid-hydrogen storage, said “bumps in the road” are inevitable with any new technology. Russ Dunn, the chief technology officer, said the company is working closely with Airbus to ensure that their development plans remain aligned.
The British government under Boris Johnson earmarked hundreds of millions towards the development of a hydrogen fuel industry.
The former prime minister said in 2021 he wanted Britain to become “the Qatar of hydrogen”.
More recently, Ed Miliband, the Energy Secretary, has also talked up the potential for the fuel and Rachel Reeves, the Chancellor, allocated billions for carbon capture and green hydrogen production in her October Budget.
However, the attention across the aviation industry is now focusing almost wholly on SAF (SAF was already the chief focus so can’t really say that attention is now suddenly turning to SAF).
A spokesman for Boeing said it continues to view SAF as “offering the largest potential to reduce carbon emissions over the next 30 years in all aviation segments”.
Airbus is also now focused on a new generation of conventionally powered jets that could be fuelled by SAF and are to be launched by the end of the decade before entering service in the late 2030s.
Notably, Reeves talked up the potential of SAF – not hydrogen – to deliver a net zero future for aviation when she threw her support behind expansion at Heathrow and other airports in her recent speech on growth.
Hydrogen may yet ride to the rescue of air travel in another form, with the element potentially playing a central role in developing feedstocks for synthetic SAFs.
Regular SAF is made mostly from recycled cooking oil, which delivers a lifetime CO2 reduction of about 70pc. However, a synthetic version of SAF can be completely carbon neutral.
It is produced by extracting hydrogen from water using electrolysis, after which it is combined with CO2 from the air to create carbon monoxide. More hydrogen is then added to create a wax that can be turned into the fuel.
However, this process requires clean energy – and lots of it. Rolls-Royce says mini-nuclear reactors will be needed to source sufficient electricity from renewable sources to power the electrolysis.
On Tuesday, a coalition of aviation companies including Air France-KLM, SAS, easyJet and Airbus sent an open letter to EU officials calling for “urgent” support for SAF production using hydrogen. The group noted that while many projects had been announced, final investment decisions were not being taken.
López de la Osa says: “I think one way or another hydrogen is still likely to play a central role in the decarbonisation of aviation.”
For now, though, the dream of a hydrogen-powered plane taking you on your next vacation looks a long way from take-off.
