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UK-based Intelligence Energy’s 300-kW IE-Flight F300 fuel cell powertrain is intended for Part 23 aircraft.
Fuel cell specialist Intelligent Energy has been selected to join the UK Civil Aviation Authority’s Hydrogen Challenge, to help the regulator define standards for certifying fuel cell systems for aerospace.
Founded in 2001, the company has long experience with the technology, including partnering with Boeing to conduct the first manned flight of an aircraft powered by a fuel cell—in 2008 in Spain.
After spending its first 10-15 years in research and development, Loughborough, England-based Intelligent Energy (IE) moved into manufacturing and now has six product lines: low-power fuel cells for drones, stationary power needs and forklift trucks; and high-power for automotive, aerospace and large-scale stationary uses.
“The different product lines have different maturity levels,” says Jonathan Douglas-Smith, head of business development for IE Flight, which makes the company’s fuel-cell systems for aerospace. While the low-power fuel cells are in full-scale production, high-power systems are in small-scale production for automotive applications.
“Our high-powered fuel-cell systems for aerospace are in development and we’ll be at around Technology Readiness Level 5 for the complete system by 2027, conducting initial customer deliveries in that year,” he says.
IE is producing hundreds of systems for drones, with commercial customers for longer range linear inspections of pipelines and power lines, and military customers for intelligence, surveillance and reconnaissance. The latter includes Aurora Flight Sciences for the 7-hr.-endurance Skiron-XLE.
While IE’s low-power fuel cells, up to 20-30 kW, are air-cooled, the high-power systems use an evaporative cooling technology developed by the company. Water is injected onto the fuel-cell stacks, where it evaporates, changing its phase to effectively cool the stacks while ensuring the fuel cells stay humidified.
Most other manufacturers of high-power proton exchange membrane (PEM) fuel cells use liquid cooling loops, with glycol as the coolant. These require separate humidifiers and heat exchangers, resulting in large and heavy thermal management systems, Douglas-Smith says.
Both power classes of fuel cell use the same low-temperature PEM technology. “We manufacture the lightest fuel cells for drones on the market, and what we are doing is combining the lightweight material we use in our drone products—which has the highest kW/kg—with the cooling solution in our automotive high-power fuel-cell systems for the IE Flight product line,” he says.
“The evaporative cooling system has been proven out in the automotive product line, and the material has been proven out in the drone product line. IE Flight is really just combining the best of those two,” he explains.
Fuel cells are about 50% efficient, meaning a system producing a megawatt of electrical power produces a megawatt of waste heat. Low-temperature PEM fuel cells typically operate at up to 80 deg.-celsius, making it difficult to remove that heat.
Efforts are underway to push up the temperatures at which PEM fuel cells operate, making it easier to remove heat.
“Because we inject water into the stack and have this phase change take place, we can then increase the temperature and pressure of the water vapor produced by adding a second stage compressor to the outlet. So we can boost that temperature up to 130-140C and reject that heat at a much higher temperature and reduce the thermal management system size as a result” Douglas-Smith says.
IE has been developing a lightweight fuel-cell stack for aerospace since 2020 and now is developing a complete system, including balance of plant, that can be plugged into an aircraft as the powertrain. Unveiled in 2024, the 300-kW F300 system is planned for delivery beginning in 2027.
The F300 is designed for use in new-design or retrofit Part 23 aircraft across sub-regional, regional and eVTOL aircraft. “It’s going to be supplied to an initial strategic launch customer in the eVTOL industry,” Douglas-Smith says. The IE-Flight architecture is scalable to multi-megawatt fuel-cell installations, making it suitable for larger Part 25 transport-category aircraft.
Development of the F300 is being supported by the UK government-funded H2Gear project, led by GKN Aerospace, which is developing a 1-megawatt cryogenically cooled hydrogen-electric powertrain for ground demonstration in 2026.
With Airbus delaying plans to field a hydrogen-electric airliner by 5-10 years, when does IE expect fuel-cell technology to enter the market? “There are customers taking the approach where, to be first to market, they are seeking supplementary type certificates on existing certified platforms, which I think will be in operation by the end of this decade, maybe even a little bit sooner,” says Douglas-Smith.
“However, from the drone world we learned really quickly that trying to bolt on a hydrogen fuel-cell system powertrain onto an existing platform that’s been designed for a different technology is not the best way to do it. It will have limited performance and function doing it that way,” he warns.
“The flip side is that having a clean-sheet design—the way Airbus is approaching it—does take a lot longer to certify and get into operation. But I’m confident that certainly by the early 2030s there will be commercial operation of fixed-wing Part 23 [hydrogen-electric] aircraft, most likely sooner on smaller subregional aircraft toward the end of this decade,” Douglas-Smith predicts.
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