By 2050, commercial aviation could carry 10 billion passengers covering 20 trillion km, resulting in approximately 2350 million t of carbon dioxide emissions, according to Deloitte.
This could represent up to 22 per cent of global emissions, a jump of 450 per cent from the 4 per cent of emissions the industry contributes today – highlighting the urgent need to develop and deploy scalable, low-emissions technologies in one of the most challenging sectors to decarbonise. Jet fuel’s unmatched energy density, the long lifespan of aircraft fleets and the complexity of safety-critical systems all contribute to the challenges the industry faces.
Work is underway to address it. According to the International Air Transport Association’s net-zero roadmap, sustainable aviation fuels (SAFs) will be responsible for two-thirds of the emissions reductions by 2050. A further 19 per cent is anticipated to come from carbon offsets and capture technologies, while emerging electric and hydrogen propulsion systems are expected to deliver around 13 per cent of the total cuts.
These projections also highlight a critical point: no single solution will decarbonise aviation alone. The sector will need a portfolio of technologies and policies working together. SAFs remain limited in supply and are expensive, while batteries can’t yet deliver the range needed for regional or commercial-scale aviation.
Read: Unpacking the numbers that make sustainable aviation fuel so challenging
Viable propulsion
In December last year, Stralis successfully completed a hydrogen-electric powered propeller spin test on Clyde, a registered six-seat Beechcraft Bonanza aircraft at Brisbane Airport.
The process used high-temperature proton exchange membrane (HT-PEM) fuel cells fuelled by green hydrogen and according to Steffen Geries, Chief Operating Officer at Stralis, it is completely emissions-free.
“Hydrogen electric propulsion uses green hydrogen, produced from renewable sources, which combines with oxygen in a fuel cell to create electricity for an electric motor, with water vapour and heat as the only by-products,” Geries said.
On the back of the successful ground testing, the company is now scaling the technology across multiple aircraft platforms.
“The first larger application will be a 15-seat retrofitted Beechcraft aircraft called B1900D-HE, designed to achieve an 800 km range, but our flagship product will be a 50-seat aircraft for regional aviation, capable of a 3000 km range,” Geries said.
“At this scale, hydrogen-electric propulsion offers its strongest performance and economic advantage – significantly undercutting the operating costs of conventional fossil-fuel aircraft in the same category.”
In the longer term, Stralis sees the potential to scale to even larger aircraft, as electric motors become more powerful and fuel cell systems continue to improve. With ongoing advancements, hydrogen-electric propulsion could extend well beyond the regional market, Geries said.
Importantly, the underlying technology isn’t limited to aviation. HT-PEM fuel cells are well-suited for any application that requires high specific power and is sensitive to weight and volume constraints.
“That includes marine vessels, heavy-duty trucking, portable power systems, and other mobility sectors where clean, lightweight and high-output energy is essential.”
Onboard storage
To get to this point, the engineering team has had to overcome one of the toughest challenges in hydrogen aviation: storage.
“Hydrogen in its gaseous form requires substantial volume, which is an issue for aircraft where space and weight are tightly constrained,” Geries said. “We’ve overcome this by storing the hydrogen on board as a cryogenic liquid at -254°C. This significantly improves energy density by volume and enables longer range capability.”
Liquid hydrogen also offers several advantages over battery-electric flight, he added.
“Where batteries add substantial weight and suffer from limited energy density and long charging times, liquid hydrogen is lighter and supports faster turnaround times. Refuelling is performed by pumping liquid hydrogen into onboard cryogenic tanks.”
Which leads to the next challenge and huge opportunity: the need for airports to transition their infrastructure to support liquid hydrogen refuelling.
“One of the major infrastructure and supply chain hurdles facing the transition to hydrogen aviation is that airports must have liquid hydrogen available onsite. It’s not just about the aircraft; the entire airport ecosystem needs to shift from fossil fuels to hydrogen as a viable fuel source.”
Fuelling challenges
However, this challenge also presents a significant opportunity. Hydrogen can be produced locally and sustainably, using electrolysis powered by renewable energy sources, such as solar.
“With the right infrastructure, including onsite liquefaction equipment, airports could generate, liquefy and store hydrogen themselves,” Geries said. “This would reduce reliance on centralised fuel distribution and create a clean, closed-loop energy system directly at the airport, ready to supply airlines with emissions-free fuel.”
Great news good to see such progress