United Airlines’ announcement Monday that it could be flying hydrogen-electric-powered regional jets by 2028 runs counter to expert consensus that development timelines will take at least twice as long given the complexity of the technology and the amount of funding required for development and commercialization.
“Sometimes showmanship trumps science and technology,” Richard Aboulafia, vice president of analysis for Teal Group, a Fairfax, Virginia, firm that provides market analysis and forecasting in the aerospace and defense sectors, said in an email. “Hydrogen is a long-term speculative bet, but with many big hurdles. There’s nothing that will be ready for use in 2028, unless it’s completely uneconomical to operate.”
Val Miftakhov, founder and CEO of ZeroAvia, the hydrogen-engine company that United has invested in, insists hydrogen flight will become a reality much sooner than many predict.
ZeroAvia is also working on a hydrogen power plant to replace engines on turboprop freighters operated by U.K.-based ASL Aviation.
Aside from the technical challenges, getting aviation authorities to sign off on an advanced aircraft design will take more than seven years, Richard Anderson, director of the Eagle Flight Research Center at Embry-Riddle Aeronautical University in Daytona Beach, Florida, told FreightWaves.
“If you tried to certify a [Boeing] 737 today from scratch with nothing new or novel, that timeline would be challenging. That’s a very optimistic timeline” for hydrogen deployment in commercial aircraft, he said.
The aviation sector accounts for about 2.5% of global carbon dioxide emissions, but its contribution to overall climate change is higher because planes also affect the concentration of other gases and pollutants in the atmosphere, scientists say. And since aviation is more difficult to decarbonize than other industries, illustrated by the switch to electric vehicles, aviation’s share of carbon emissions is expected to rise in the future. The aviation industry is crossing its fingers for a technological breakthrough over the horizon that will decarbonize air transport by 2050 but is emphasizing sustainable aviation fuels as a bridge until it can get there.
Hydrogen-electric engines use electricity created by a chemical reaction in a fuel cell to power an electric motor instead of burning fossil fuel. Because no fuel is burned, no climate-harming carbon is released into the atmosphere when the engines are operated.
European aircraft manufacturer Airbus has said it is confident it can develop a hydrogen fuel cell propulsion system by 2035. Boeing officials say it will take longer for them to develop because of the technical challenges.
Even if hydrogen fuel engines eventually work, experts say they likely will be limited to short-haul commuter-type aircraft, at least initially. Notably 85% of emissions are on trips over 930 miles, according to IBA. The London-based aviation consulting firm said during a recent webinar that the entry into service of hydrogen planes by 2035 is unlikely.
There are many challenges that scientists and engineers have to solve before hydrogen becomes viable as a power source for commercial aircraft.
Liquid hydrogen, for example, takes up four times as much volume as jet fuel and has to be kept at a very low temperature. Storage of hydrogen as a gas requires high-pressure tanks.
“We have some physics problems for hydrogen in terms of volume. Eighteen percent more volume has to be carried, and we have to compress this gas at minus 250 degrees Celsius to liquify it to create that efficiency,” Stanley Deal, Boeing’s CEO of commercial airplanes, said during a panel discussion at the International Air Transport Association’s October annual general meeting in Boston.
A 2020 study by management consultancy Roland Berger identified five barriers to overcome before hydrogen technology becomes a viable energy system for aviation, including aircraft and engine redesign; and storage using advanced light-weight tanks and cryogenic cooling systems.
Also requiring development, experts say, are a hydrogen fuel supply chain, with fuel produced using renewable sources rather than natural gas, and a distribution system to get it to the airport.
It will take four to five years to mature the technology for hydrogen propulsion systems, an additional two years to establish a production program, and then seven or eight years to roll it out, Airbus CEO Guillaume Faury predicted at the IATA event.
“If you tried to certify a [Boeing] 737 today from scratch with nothing new or novel, that timeline would be challenging. That’s a very optimistic timeline.” – Richard Anderson, director of the Eagle Flight Research Center at Embry-Riddle Aeronautical University.
United Airlines (NASDAQ: UAL) said Monday that it has taken an equity stake in ZeroAvia and expects to buy up to 100 of the startup company’s hydrogen-electric engines. But there is no firm commitment to purchase yet.
Chicago-based United said it will pursue a purchase agreement for 50 ZeroAvia engines, with an option for 50 more, on condition that they meet its operational, safety and sustainability requirements. It said the engines could replace kerosene-powered jet engines on its United Express fleet as early as 2028 — pending full development and certification by regulators. A potential candidate for the engine retrofit is the 50-seat CRJ-550, it said.
At two engines per aircraft, an initial order would equip 25 to 50 aircraft.
The hydrogen announcement is not the first time United has raised eyebrows with splashy news about quick adoption of a breakthrough technology.
Last summer, United signed a letter of intent to buy 15 supersonic jets from a startup company called Boom and said they will enter passenger service in 2029 even though the plane is still under design, doesn’t have an engine yet and must be certified by aviation authorities. Skeptics question whether an aerospace startup has the billions of dollars in capital necessary to start manufacturing from scratch and say the supersonic model doesn’t work for commercial air travel because the aircraft are fuel-intensive, requiring five to seven times as much jet fuel as conventional aircraft. They also can’t be flown over land because of noise concerns. And if sustainable aviation fuels are used, as Boom Supersonic and United claim, the cost of fuel will be three or four times higher because there is such limited supply.
ZeroAvia, with dual headquarters in Hollister, California, and the U.K., said United is part of a $35 million fundraising round that includes Alaska Airlines (NASDAQ: ALK). Existing investors include Amazon’s Climate Pledge Fund and venture funds for energy company Shell (NYSE: RDS), Bill Gates’ Breakthrough Energy and three portfolio investment groups. Total investment in ZeroAvia to date is $115 million.
“Hydrogen-electric engines are one of the most promising paths to zero-emission air travel for smaller aircraft, and this investment will keep United out in front of this important emerging technology,” said Scott Kirby, CEO of United, in a news release. “United continues to look for opportunities to not only advance our own sustainability initiatives but also identify and help technologies and solutions that the entire industry can adopt.”
ZeroAvia’s road map calls for it to develop hydrogen-electric propulsion for progressively larger aircraft. The company says it is on track to commercialize its hydrogen propulsion technology in 2024, starting with a 10-to-20-seat aircraft, as well as package delivery aircraft.
On Tuesday, Canadian manufacturer De Havilland announced a development partnership with ZeroAvia for the Dash-8 turboprop and an option to purchase 50 hydrogen-electric engines for existing aircraft.
Alaska Airlines is contributing resources to the development program. Alaska and ZeroAvia engineers will work together to scale the company’s existing powertrain platform to produce the ZA2000, an engine family capable of producing between 2,000 and 5,000 kilowatts of power with a 500-mile range. Alaska Air Group will donate a De Havilland Q400 turboprop aircraft previously operated by subsidiary Horizon Air, capable of transporting 76 passengers. ZeroAvia will set up a location in the Seattle area to support the initiative. Alaska has options for 50 engine retrofit kits.
ZeroAvia says it has 460 options to purchase its engines, including those from United and Alaska.
The new funding round targets the next segment of 40-to-80-seat turboprops by 2026 and regional jets by 2028. The company has so far flight-tested a six-seater aircraft, has secured experimental certificates from U.S. and U.K. aviation authorities, and will soon begin ground tests of its ZA600 engine in a 19-seat aircraft, with the aim of entering commercial service with the smaller engine by 2024.
Hydrogen freighters
Under the ASL deal, ASL Airlines Ireland will provide a retired ATR72 freighter to ZeroAvia for program development and subsequent use as a demonstrator. ASL will then convert several owned aircraft to the zero-emission engines beginning in 2026. Dublin-based ASL Aviation owns six cargo subsidiaries, including four that operate in Europe carrying freight for customers such as DHL, FedEx (NYSE: FDX), Amazon (NASDAQ: AMZN), and two joint ventures in South Africa and Thailand.
“ZeroAvia’s hydrogen-electric powertrain will allow us to operate cost-effective regional freight services using existing aircraft that are now powered by traditional turbines. ZeroAvia’s early flight test successes are promising, and we are also excited by the extensive R&D they have put into the green hydrogen production and the refueling ecosystem needed to support air operations,” said ASL Aviation CEO David Andrews in an announcement early last month.
ZeroAvia will also collaborate with ASL on the development of its ZA2000 engine.
To support the refueling of these aircraft, ZeroAvia is working toward scaling its already developed Hydrogen Airport Refuelling Ecosystem, which was developed with U.K. government assistance. In addition, ZeroAvia was recently awarded a new transport research and innovation grant from the U.K. Department for Transport to explore concepts for liquid hydrogen refueling in an airport setting.
Zero-CO2 without offsets
Chicago-based United is pushing hard to achieve its goal of eliminating 100% of greenhouse gas emissions from its fleet by 2050, without relying on traditional carbon offsets. There are three legs to its approach: becoming more efficient in using conventional jet fuel through better engines, more direct routes and other operational improvements; sustainable aviation fuels; and new technologies, such as hydrogen. And it is investing in startup companies to help build up these new industries.
On Dec. 1, United operated the first passenger flight using 100% sustainable aviation fuel, from Chicago to Washington, demonstrating the safety of SAF. Currently, airlines are only permitted to use a maximum of 50% SAF on board, but United met the standard by using 100% SAF in one engine and conventional fuel in the other, instead of blending the fuels.
Earlier this year, United announced a record-setting agreement to purchase 1.5 billion gallons of alternative fuel from non-petroleum feedstocks from Alder Fuels and has now committed to purchase nearly twice as much of this fuel as the rest of the world’s airlines combined.
Alder Fuels is a clean-tech company developing new technologies for producing SAF at scale by converting biomass, such as forest and crop waste, into low-carbon replacement for traditional aviation fuel. United said that the Alder technologies, coupled with a special refining process developed by Honeywell, could produce a carbon-negative fuel that pulls CO2 from the atmosphere.
According to the U.S. Department of Energy, U.S. forestry residues and agricultural residues alone could provide enough biomass energy to generate more than 17 billion gallons of jet fuel and displace 75% of U.S. aviation fuel consumption. If the U.S. were to broadly adopt regenerative agricultural practices, which capture more carbon in healthier soil compared to traditional methods, the country could generate an additional 7 billion gallons of SAF, which would completely replace the U.S.’s current fossil jet fuel consumption, United said.
The company is also an investor in Fulcrum BioEnergy, where United has an option to purchase up to 900 million gallons of additional SAF.
Many airlines are trying to help accelerate production of SAF at the scale needed for regular use in daily operations. Currently there is only enough SAF to support 2% of the world’s flying, according to the International Air Transport Association. SAF is about four times more expensive than conventional fuel.
In July, United’s venture capital arm announced that along with Breakthrough Energy Ventures and Mesa Airlines (NASDAQ: MESA), it has invested in electric aircraft startup Heart Aerospace. Heart Aerospace is developing the ES-19, a 19-seat electric aircraft that has the potential to fly customers with zero emissions when powered by renewable electricity. United is also working with Archer Aviation to help it accelerate development of an electric “air taxi.”
Electric power won’t work on large, widebody planes that are the primary form of air transport for cross-border shipments, United CEO Kirby recently said.
“Technology is only going to take us so far because the reality is flying big airplanes long distances isn’t going to be done with batteries. They simply don’t have enough energy density. No matter how efficient you make the engines, it requires a lot of energy to get a several-ton airplane off the ground and fly it,” he said on the Nov. 18 edition of the “Leadership NEXT” podcast from Fortune.
United is also investing to support direct air capture, a carbon capture and sequestration technology that involves pumping CO2 underground where it can be stored for millions of years.
“Traditional carbon offsets are not going to solve this problem. … There is simply not enough space on the planet to plant enough trees to soak up all the emissions that mankind is producing. And in fact if we planted every square acre of land on the planet that could grow trees it would account for less than five months of mankind’s emissions,” Kirby said on the Forbes podcast. “There’s nothing wrong with planting trees, but when 99% of corporate America is relying solely on planting trees as their way to market to consumers that they are net zero, it won’t work.”
On another podcast, produced by Salesforce, Kirby said, “It drives me crazy that essentially every corporation [is using carbon offsets] — because it’s easy. That’s a marketing message.”
Click here for more FreightWaves/American Shipper stories by Eric Kulisch.
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