YYesterday, the world’s largest hydrogen-powered plane took off from an airport in the UK, circled 10 miles in the air, and landed again about 10 minutes later. The plane, a 19-seat Dornier 228 turboprop extensively modified by startup ZeroAvia, wasn’t exactly a jumbo jet, but it still represents a significant step in the nascent world of zero-emissions flight. The previous record for the largest hydrogen aircraft, also held by ZeroAvia, was for a 6-seat aircraft.
On board, a pair of fuel cells converted hydrogen into electricity to run an electric motor on the plane’s left wing, aided by a lithium-ion battery that added additional power during takeoff. In case something went wrong with the zero carbon setup, the plane’s other propeller was powered by a conventional kerosene engine. And to keep things simple, the test plane only had about 10 kilograms of hydrogen on board (22 pounds), enough to fly for about 30 minutes. “In the destination settings for commercials [flights], we are seeing 80 to 100 kilos of hydrogen on board. So significantly more range,” says Val Miftakhov, CEO of ZeroAvia.
This current aircraft is a stepping stone into the company’s larger ambitions. They are now working on a hydrogen power system for a 76-seat regional jet, which could be ready around 2026.
The aviation industry produces approximately 2% of all humanity’s carbon dioxide emissions, a share that is expected to grow as air travel expands, with many analysts expecting the sector to triple by 2050. Finding sustainable alternatives is critical. But the physical constraints that the planes operate under—they have to be light, refuel quickly, and have enough stored energy on board to travel a decent distance before having to refuel again—mean that making a green replacement is more difficult than, say, , building electric cars.
Some start-ups are working to develop all-electric, battery-powered aircraft, with some successalthough many designs are relatively small. Alice, a battery-electric plane developed by startup Eviation, which had its first short test flight last fall, it can carry nine passengers. The largest battery-powered plane, an electrified Cessna Grand Caravan that first flew in 2020, can carry 14 passengers. Other companies are betting on so-called “e-fuels”, which use chemical processes to convert renewable energy into liquid fuels like kerosene, which could then be used by planes of any size, and many airlines are investing in scale up this seemingly simple solution. But many processes to produce that fuel rely on organic raw materials, and ultimately there may not be enough to go around. That leaves batteries and hydrogen as two longer-term clean energy solutions.
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Miftakhov, a former EV charging entrepreneur, says battery-powered planes have the potential to decarbonize the market for small, short-range planes, but hydrogen is the only reasonable option to decarbonize longer routes that planes fly on. bigger. “If you do the math, there’s actually a limitation on how much power you can store in the battery,” Miftakhov says. “You won’t be able to run a 787 over the Atlantic on that power source.”
Those longer flights account for most of the airline industry’s emissions. In 2020, long flights of more than 4,000 km (2,485 miles) made up just 6% of all flights departing from European airports, but accounted for more than half of total flight emissions, according to to analysis by Eurocontrol. Shorter flights of 500 km (310 miles) or less, the approximate target range for battery-electric aircraft companies, accounted for around 30% of outbound flights and 4% of emissions.
For battery-powered flight to compete beyond extremely short flight paths, Miftakhov says, batteries would have to store much more energy, charge very quickly, and last for thousands of battery cycles before needing to be replaced. “These are in natural conflict with each other,” he says. “Moving these three by an order of magnitude each is a monumental challenge.”
Hydrogen, on the other hand, has enough energy density to power the largest planes, according to Miftakhov. (Although even compressed hydrogen occupies a larger volume on board an airplane than conventional kerosene.) The European aircraft giant Airbus, for example, is working on the development of large hydrogen engines, which it claims will be able to show in the next four years. And unlike e-fuels, hydrogen production doesn’t require complicated chemical processes; it can even be produced at an airport if required.
“Eventually, I think it’s all going to be… electric motors powered by hydrogen fuel cells,” says Miftakhov. “In 15 to 20 years, obviously uncertain, we will get the technology to a point where it can power some of the largest aircraft out there.”
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