Accounting for over 12% of total transportation emissions, aviation is one of the fastest-growing sources of greenhouse gas emissions. Pre-pandemic data estimated that global aviation – which includes passenger and freight – emitted roughly 1 billion tonnes of carbon dioxide. And that number is expected to grow at a rapid pace, on the way to doubling by 2050.
Hydrogen and electric propulsion systems are being developed towards the goal of net-zero flight. However, the question of when will hydrogen-powered flight be more than just a pie in the sky has remained somewhat vague – until now.
In about three years, passengers will be able to fly between the UK and the Netherlands on board a hydrogen-electric aircraft developed by ZeroAvia, powered by the first practical true zero-emission aviation powertrain.
Scaling up.
Engineers at ZeroAvia retrofitted the 19-seat Dornier 228 aircraft with twin 600-kilowatt hydrogen powertrains. (The standard Dornier 228 engine, Honeywell TPE331 turboprop, produces 579 kilowatts). The planes will have an 805-kilometre (500-mile) range, with 100 kilograms (220 pounds) of compressed hydrogen onboard. Check out this video of the 600-kilowatt powertrain being tested. It successfully dragged a 15-ton test truck across the tarmac at the company’s headquarters in California as its engine roared to life.
Moving forward, ZeroAvia is scaling its existing technology to create an engine family capable of producing between 2,000 and 5,000 kilowatts of power. The next zero-emissions aircraft, anticipated to take to the skies in 2026, will serve up to 80 passengers.
Timeline for the development of powertrains at ZeroAvia. Photo credits: ZeroAvia
Shades of hydrogen.
Of course, for hydrogen aircraft to accelerate the world’s transition to sustainable aviation, the hydrogen fuel used must be green.
Not all types of hydrogen generation are compatible with net-zero emissions or sustainable, climate-positive use. Here are the three main categories of hydrogen that you need to know.
Grey hydrogen is produced from fossil fuels via the steam methane reforming (SMR) process. It’s currently how most of the world’s hydrogen is produced and its carbon footprint is nothing to write home about.
Similarly, blue hydrogen is also produced from fossil fuels via the SMR process. However, carbon released during the process is captured, stored and used for other purposes. This lowers, or delays, its carbon footprint.
Contrariwise, green hydrogen is produced with electricity from low- or zero-carbon energy sources. Green hydrogen forms a cornerstone of the shift away from fossil fuels and can provide a link between growing renewable electricity generation and sectors where emissions are hardest to abate.
While currently the weight of electro-chemical batteries is what’s preventing battery-electric planes from taking off, it may be time for green hydrogen to pull its weight in tackling the hard-to-abate sectors such as aviation.
Working toward a decarbonised economy by mid-century requires innovation on all fronts. From water-burping cars to aeroplanes powered by the lightest molecule on Earth, hydrogen will be one of the crucial factors to get humanity on track to reach net-zero emissions.
