Seattle-based Alaska Airlines is partnering with US-UK hydrogen-electric aircraft developer Zeroavia to retrofit its fleet of 76-seat De Havilland Q400 short-haul aircraft with a hydrogen-electric powertrain.

Alaska Air’s Seattle hub will act as the starting point for the transition, as the joint venture will need to construct onsite hydrogen production and develop a hydrogen refuelling network to serve an initial round of flight destinations.

While Zeroavia has not attempted this size of retrofit before, the company has flown a six-seat prototype and is about to test fly two 20-seat Dornier 228s fitted with 600kW Zeroavia fuel cell hydrogen powertrains.

The schedule to have the Alaska Q400s ready to test is also coming along at a fast pace. “Our plan is to have the first test flights of the Q400 in 2023,” says Lev Miftakhov, CEO of Zeroavia, which will also establish a presence at Alaska’s Seattle hub.

“1kg of hydrogen carries three times as much energy as 1kg of jet fuel” Miftakhov, Zeroavia

The economic proposition of a hydrogen-electric powertrain in smaller aircraft is quite compelling, according to Miftakhov. Because fuel and maintenance costs are so high— costing about 50pc of an airline's operating expenses—margins in the air travel business are razor thin.

But the hydrogen powertrain offers much lower maintenance costs, higher energy density and higher efficiency than the jet-fuel system. “So when you come in and say, ‘on fuel and maintenance, I can offer you some savings’, it is pretty straightforward, right?” says Miftakhov.

Part of the easy differential, he points out, is that the Q400 prop engines are so inefficient to begin with. In his view, hydrogen-electric aircraft will eventually be able to undercut the jet-fuel system because their efficiency is already meaningfully higher, at roughly 60pc versus 25-30pc. And the theoretical efficiency of hydrogen-electric is even higher, as high as 90pc, he adds. This same efficiency potential has also caught the eye of short-haul trucking firms.

Shell backing

Of course, the hydrogen-electric powertrain must be supplied with fuel, and here is where the cost challenges start to mount if total emissions reduction is the goal, because green hydrogen is still tied to rather costly electrolysis. But Zeroavia is committed to producing hydrogen onsite using renewable power, so transportation costs are entirely cut out.

“We are partnering with several energy companies, and Shell is one of the major investors in the company,” says Miftakhov. “Shell is the largest aviation fuel supplier, the largest hydrogen producer, they own about a third of the hydrogen fuelling stations in California, and they are building green electrolyser capacity.” He also points out that Zeroavia has just partnered with Schiphol Airport to serve the company’s aim to offer hydrogen-powered international flights between London and Amsterdam.

Miftakhov says that, when you compare the cost of non-locally produced hydrogen, given its transportation and supply chain costs, with onsite green hydrogen, which he estimates at $3-4/kg, the differential offers a reasonable cost proposition for an airline.

$3-4/kg – Estimated onsite green hydrogen production cost

He also acknowledges that, using today’s price points, the hydrogen powertrain for flight is less competitive for larger commercial aircraft because of scaling, and that far more efficient engines in that class present a more formidable barrier to crack. But hydrogen’s fundamental energy density will clearly place pressure on oil-based systems and their economics.

“Hydrogen is the most chemically energetic fuel that exists. Just 1kg of hydrogen carries three times as much energy as a 1kg of jet fuel. But we are using it twice as efficiently,” says Miftakhov. 

As part of the joint venture, Alaska Airlines will also become an investor in Zeroavia, following previous investments in the company by Amazon’s climate fund, Bill Gates’ Breakthrough Energy Ventures and Shell Ventures.

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Author: Gregor Macdonald