Will hydrogen succeed?

Though small amounts of nitrogen oxides are produced when hydrogen is burnt in air, it does not emit carbon dioxide. Through methods such as lean burns, exhaust gas recirculation, or staged combustion, hydrogen engines can be engineered to produce only a tiny fraction of the nitrogen oxides produced by burning fossil fuels.

In the environmentally sensitive aviation industry, it is no surprise that hydrogen has long been touted as an idyllic replacement for traditional aircraft fuel. Its environmental footprint is significantly lower than that of traditional aircraft fuels, such as kerosene-based Jet A or Jet A-1.

But global aviation infrastructure is set up to accommodate traditional aviation fuel sources, meaning widespread change is slow, expensive and disruptive.

And hydrogen itself has challenges. It is very light, and when in a gaseous form, hydrogen escapes Earth’s atmosphere and is lost to space. Most of today’s usable industrial hydrogen is created as a byproduct of the fossil fuel industry, which offsets the environmental benefits.

Using renewable electricity to split water via electrolysis produces hydrogen, offering a greener solution to the production problem.

It is this seesaw of benefits and drawbacks that makes hydrogen in aviation such a challenge. The question is, will the potential it offers ever offset the challenges it faces?

The UK government is betting on the potential, committing £7.3 million to hydrogen-powered aircraft in July 2026. This forms part of a British-led “Jet Zero” R&D programme that was initiated by the UK government in January this year.

The motivation here appears to be rooted in economic drivers, with the development of a potentially sustainable fuel source linked to the creation of new skilled jobs to benefit those living in the UK.

This sentiment was outlined by the UK’s Heidi Alexander, Secretary of State for Transport, who said of the recent funding: “By powering up electric and hydrogen-powered planes, we’re bringing passengers closer to the flights of the future – while creating skilled jobs, backing UK businesses and spreading economic growth to all 4 corners of the country.”

“We’re working hand in hand with industry to cut emissions, drive innovation, and ensure the UK remains one of the best places in the world to build, test and fly the aircraft of tomorrow,” she said.

Core to this British initiative was a Zero Emission flight demonstration competition, with eight projects securing a slice of £7.3 million in funding. This is part of a broader £43 million next-generation aviation push, supported by the UK government.

Fuel cells

There are two pathways for powering an aircraft with hydrogen. The first is to burn it in a gas turbine engine, much like a contemporary jet engine burns jet fuel. The second is through a fuel cell, which generates electricity through an electrochemical reaction.

Fuel cell technology is not new. In fact, the now-retired NASA Space Shuttle famously utilised hydrogen fuel-cells for a variety of tasks, including electricity generation, onboard heating and the production of fresh water.

Fuel cells offer great promise for light aircraft, with potential benefits for air taxis and drones. However, there is also potential for general aviation and even smaller regional aircraft.

One such example is Joby Aviation, a New York Stock Exchange-listed company. Joby traces its heritage back to 2009. Back then, it was not a hydrogen-focused company, but it did have a goal of exploring alternative ways to cleanly take flight. By 2017, its first full-scale demonstrator took flight, utilising electric propulsion and a vertical take-off and landing (VTOL) configuration.

Fast forward to 2021 and Joby quietly acquired German hydrogen fuel‑cell aviation company H2Fly, which it maintains as a subsidiary to this day. As the US company continued to develop air taxi designs, the acquisition broadened Joby’s reach and brought Hydrogen front and centre, setting the stage for a technology-driven partnership.

In 2024, Joby’s demonstrator was fitted with a hydrogen-electric system that utilises both fuel cells and a liquid hydrogen fuel tank. This configuration allowed it to complete a record flight of over 830km. This was a significant improvement over its battery-powered demonstration flights, achieving more than three times the range.

Importantly, the same demonstrator had already accumulated thousands of battery-powered test flights before being converted to hydrogen-electric propulsion, which offered a robust baseline for comparing the two propulsion systems.

At the time of the record flight, JoeBen Bevirt, founder and CEO of Joby, said: “The vast majority of the design, testing and certification work we’ve completed on our battery-electric aircraft carries over to commercializing hydrogen-electric flight.”

Bevirt noted that when in service, Joby expect to be able to use the same landing pads, operations team, and software that will support the commercial operation of the firm’s battery-electric aircraft.

Hydrogen burn

Another approach is to burn hydrogen directly in a gas-turbine engine. On most demonstrators to date, hydrogen is stored as a cryogenic liquid before being vaporised and combusted in the engine.

NASA has investigated the potential of hydrogen-driven jet engines several times. Its predecessor, NACA, commenced work when the Lewis Research Centre developed and flight-tested a Martin B-57 Canberra with one of its engines powered by hydrogen.

In the 1970s, NASA worked with Lockheed Corporation to explore the feasibility of hydrogen airliners capable of transporting 130 passengers over a range of 2,780km, 200 passengers over 5,560km, and 400 passengers on a 9,265km flight.

During the study, liquid hydrogen was compared with conventional fuels across a range of ranges and payloads to simulate different aircraft uses, from short-haul narrow-bodies to long-range wide-bodies.

The Soviet Union also investigated hydrogen-powered airliners, with a Tupolev Tu-154 modified to run one of its three engines on liquid hydrogen from 1988. Designated the Tu-155, this testbed was fitted with a Kuznetsov NK-88 turbofan and used to test hydrogen fuel. This was supplemented by liquefied natural gas testing before the programme was irreversibly disrupted by the chaos surrounding the Soviet Union’s collapse.

In more recent times, Boeing investigated liquid hydrogen-powered, high-altitude aircraft with its Phantom Eye demonstrator. Developed by the US-manufacturer’s Phantom Works, the aircraft was part of the rapid prototyping initiative.

Designed to remain active for long durations and fly as high as 65,000ft, the Hydrogen-powered Phantom Eye made its maiden autonomous flight in June 2012, with its ninth and final flight taking place in 2014. That last flight lasted over 8 hours and achieved a height of 54,000ft.

Zero to hero?

European manufacturer Airbus made headlines in 2025 when it identified hydrogen fuel-cell electric propulsion as its preferred technology for its ZEROe programme. It came after a successful 1.2MW hydrogen propulsion system demonstration in 2023, as well as end-to-end ground testing of integrated fuel cell stacks, electric motors, gearboxes, inverters, and heat exchangers in 2024.

Last year, spirits were high as Airbus plugged the benefits of its ZEROe approach at its annual summit, noting the successful selection of fuel cells while acknowledging valuable lessons learnt from investigating burning hydrogen.

At the summit, the manufacturer recommitted to bringing a commercially viable hydrogen-powered aircraft to market, with a revised entry date of ‘the second half of the 2030s’ touted.

At the time, Airbus Head of the ZEROe Project, Glenn Llewellyn, said: “Over the last five years, we have explored multiple Hydrogen-propulsion concepts, before down-selecting this fully electric concept. We are confident it could provide the necessary power density for a hydrogen-powered commercial aircraft and could evolve as we mature the technology.”

“In the coming years, we will concentrate on advancing the storage, distribution and propulsion systems, while also advocating for the regulatory framework needed to ensure these aircraft can take flight,” he added.

However, the enthusiasm must be viewed alongside significant challenges, with Airbus itself delaying the ZEROe timeline. Further, it was widely reported that the Toulouse-based manufacturer scaled back funding for the programme in early 2025.

Analysts pointed to the slower-than-expected development of the hydrogen fuel ecosystem, as well as a readjustment of expectations to align with a more realistic timeline now that fuel cells have been selected as the preferred approach.

And Airbus is not alone in facing challenges. Several start-ups globally have faced significant challenges in the last 12 months, with global investment uncertainties and lengthening timelines having knock-on impacts on investment.

There is no doubt that hydrogen offers great promise for aviation, and a pathway appears to be slowly clearing towards a possible Hydrogen future.

But the same could have been said in the 1970s in the NASA hallways, or the 1980s at the Tupolev design bureau, or at Boeing’s Phantom Works more recently. Each time, the technical potential of Hydrogen was shown. Yet the Hydrogen in aviation remains in its infancy.

Thus, the real question is not whether hydrogen could power the future of aviation; it is whether there’s enough money, belief, determination and drive to shift an industry from the tried-and-true jet fuel to a new, more sustainable future.