United Airlines and Alaska Airlines have placed another bet in the airline industry’s push to go carbon-neutral by the middle of the century. This airlines are investing $35 million in hydrogen-powered aircraft through engine developer ZeroAvia with an eye on deploying its zero-emission hydrogen-electric engines in less than a decade.
Chicago-based United made the biggest commitment with a conditional order for 50 of ZeroAvia’s proposed ZA2000 family of engines, and specifically for one that could power a 50-seat regional jet. The company aims to certify the engine by 2028 after which United could retrofit them on regional jets in its feeder fleet, including the Bombardier CRJ550. United also has options for another 50 engines from ZeroAvia.
Seattle-based Alaska is also partnering with ZeroAvia on the ZA2000 family but to power the de Havilland Dash 8-400s in its feeder fleet. The partnership, which was first unveiled in October, includes the donation of a Dash 8 to support development of the engine that could fly up to 500 miles, and options for up to 50 powerplants.
The investments — and engine commitments — are just the latest sign of the growing importance emission reductions at airlines. The industry as a whole has committed to net-zero emissions by 2050 through IATA. But each airline individually is taking its own track to get there: From new sustainable aviation fuel (SAF) offtake agreements at American Airlines, British Airways, and — according to CEO Alan Joyce — soon Qantas, to the surge in interest in helicopter-like electric vertical takeoff and landing, or eVTOL, aircraft from Airbus to Azul.
Hydrogen-electric engines are just one path that the industry is looking at to wean itself off of fossil fuels. Along with ZeroAvia, Airbus is working on developing a hydrogen-powered aircraft that could enter service by 2035. Other firms, including Archer Aviation and Heart Aerospace, are focused on battery-powered propulsion that would be rechargeable like electric vehicles. The problem with the latter is that current battery technology is only able to power small aircraft a short distance — hence the surge in all-electric eVTOLs that could carry four people 50-100 miles — before the batteries’ weight becomes too much for economic flight.
Massachusetts Institute of Technology Professor Steven Barrett, who leads the electric aircraft initiative at the university, recently told MIT Climate that liquified hydrogen is “many times more energy-dense than even the most exotic battery.” However, there are still storage and infrastructure challenges to adapting the technology to aircraft, he added.
United Airlines Ventures President Mike Leskinen agreed with Barrett’s view that the associated infrastructure getting hydrogen to airports and onto planes are the technology’s biggest hurdles. United would likely address this by deploying any hydrogen-powered aircraft in only certain markets, for example basing them at Houston Intercontinental and flying on just specific routes.
Of course, limiting the technology to certain markets creates its own operational headaches that airlines do not face today when aircraft can be easily swapped for another and fly most places their range allows.
“You don’t need some technological innovation to make the engineering work,” Leskinen said of the hydrogen-powered fuel cell technology that ZeroAvia is using for its propulsion system. Of course the developer still must certify its powertrain, an engine, and then ultimately retrofitting that engine onto an existing airframe before any revenue passenger will fly on a hydrogen-powered aircraft.
Asked what United’s deliverables are from ZeroAvia in order to finalize its commitment, Leskinen said they include “economic” aspects of the engine, including its range and payload capabilities. The airline needs an engine that can power an at least 46-seat regional jet for up to 500 miles, he added.
At a recent event in Washington, D.C., pushing for federal SAF subsidies, United CEO Scott Kirby acknowledged that the industry was far from achieving its net-zero goal. He called a Chicago-Washington flight powered by half SAF and half fossil fuels “an important milestone” in the the shift to low- and zero-emission fuels but emphasized that more needed to be done, including financial investments by both the public and private sectors.
“We don’t expect 100 percent of them to be successful,” Kirby said of the airline’s sustainability investments. “We recognize that this is a brand new industry, and we’re willing to invest even when we don’t know every answer.”
The new investment in ZeroAvia, which Leskinen declined to provide specifics on, joins previous ones in Archer, SAF producer Fulcrum BioEnergy, and Heart. United Airlines Ventures has $200 million in funding and aims to make anywhere from six to 12 investments annually.
The question facing all of the battery- and hydrogen-electric aircraft announcements are entry-into-service targets. Many in the industry question whether these engines and aircraft will meet ambitious timelines that would see the first in revenue passenger service by as early as 2024 — just three years hence. In the U.S., the Federal Aviation Administration is not known for moving quickly, and has yet to certify any of the propulsion systems, let alone the engines or the airframes that they will power. That said, many do expect electric aircraft to carry revenue passengers at some point but most think that will occur closer to the end of the decade.
ZeroAvia began testing a hydrogen-electric engine on a six-seat Piper propeller plane in 2020. And the company plans to begin ground tests of its ZA600 engine on a 19-seat aircraft in the coming months.