Hydrogen-powered aviation continues to advance behind the scenes despite a visible slowdown in public momentum, according to Professor Phil Longhurst of the UK’s Cranfield University.
Speaking at the British Compressed Gases Association (BCGA) conference, Longhurst said sustainable aviation fuel (SAF) would likely dominate the sector’s immediate decarbonisation pathway, while hydrogen remains a longer-term solution for aviation’s net zero ambitions.
“Things have publicly stalled and are privately progressing,” he said, referring to hydrogen aviation development.
“I think SAF is going to be the immediate short term change in the next five to 15 years, whereas hydrogen is likely to be in the 25 to 40 [year range],” he added.
It could also make up for around 60% of the aviation industry’s decarbonisation efforts.According to the EU’s ReFuelEU Aviation regulation, SAF must reach a minimum of 70% of aviation fuel at EU airports by 2050.
This is partly due to SAF’s ability to work with existing aircraft infrastructure, saving costs. However, feedstock availability is the major challenge.
“There are many companies looking at SAF … [but] it’s really a feedstock challenge,” said Longhurst.
These feedstocks include waste oils, straw, plastics, and biomass, though scaling supply sustainably remains one of the sector’s biggest hurdles.
However, the sector cannot progress on efficiency alone and technologies must advance.According to Longhurst, by improving aircraft technology, the aviation sector could make up for around 22% of the decarbonisation pathway. Operational or infrastructure improvements could make up for around 10%.
“If we looked at what we’ve got to do in terms of what the options are to get to net zero … the contribution we can make with technology changes in aircraft without changing the fuels, we think we can to about 22%,” said Longhurst.
This includes building better engines and lighter aircraft, in addition to direct routing and lower drag aircraft.
“If we continue to burn fossil fuels, there’s no gain, we will just continue to fail.”
Hydrogen is still firmly in the sights of the industry when it comes to long-term decarbonisation due to its energy density.
“It has a fantastically high energy density compared to other fuels,” said Longhurst.
However, storage, containment and safety remain major barriers to deployment.
“The difficulty is containing it,” he said. “What we know is that any material we present hydrogen to, hydrogen will find its way through.”
Longhurst also highlighted leakage, embrittlement, refuelling and cryogenic storage challenges as key obstacles for hydrogen-powered aircraft.
The risks surrounding leakage became reality in 1930, when a hydrogen-filled British airship crashed in northern France during its maiden voyage to India.
Following the crash, the five million cubic feet of hydrogen used for lift ignited, causing a catastrophic fire resulting in the deaths of 48 of the 54 people on board.
However, hydrogen-powered aircraft are becoming safer through advanced cryogenic storage and improved material science to prevent embrittlement.
Companies like Airbus through its ZEROe project and Boeing with its tests are creating new safety protocols for hydrogen handling in both flight and ground operations.
Developments in cryogenic storage for liquid hydrogen and advances in fuel cell technology also enable much safer conditions for aviation.
Longhurst said smaller hydrogen fuel-cell aircraft were likely to emerge before larger liquid hydrogen-powered commercial aircraft.
“You’re likely to see that as the first steps – small, either conventional or vertical takeoff aircraft being fuel cells powered by hydrogen,” he said.
Longer-range aviation, meanwhile, would likely rely on liquid hydrogen systems due to fuel density requirements.
Longhurst also discussed future “zero corridor” concepts between airports equipped with hydrogen refuelling infrastructure, including routes such as Heathrow-Singapore.
“Can we have a zero corridor where you have refuel on either end and a few safety stops in between and just rely on a return flight process?” he said.
He also outlined several hydrogen-related projects underway at Cranfield, including hydrogen integration laboratories, engine test centres for gaseous and liquid hydrogen, and runway upgrades designed to support future hydrogen aircraft testing.
The comments come as King’s College London and Cranfield University announced they had signed an agreement as the first step towards a merger, with the aim of bringing the two institutions together from August 2027.
