Major airlines are getting serious about hydrogen-powered planes

Delta, Airbus and others are launching tests to find the best way to replace dirty jet fuel.

A white airplane takes off from a runway spewing clouds of fumes
A Delta passenger jet spews fumes at takeoff. (Delta)
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Whether they’re crammed into knee-crushing economy seats or lounging in first-class pods, all airline passengers have one travel experience in common: Their aircraft is burning lots of fossil fuels as it hurtles through the clouds. Petroleum-based jet fuel has powered passenger planes since the start of commercial air travel, and today’s global fleet guzzles billions of gallons over millions of flights every year.

In recent weeks, aviation companies have made significant early moves to begin replacing polluting jet fuel with hydrogen. The carbon-free gas could — if produced using renewable electricity — offer a possible long-term solution for curbing the greenhouse gas emissions that come from hauling people and cargo in the sky, experts say.

Delta Air Lines is partnering with Airbus to develop a hydrogen-powered passenger plane and explore the complicated question of how to store and supply the fuel at airports, the two companies said last week. Airbus, the world’s largest aircraft manufacturer, is also building a demonstration engine to test hydrogen propulsion in one of its A380 superjumbo jets. Meanwhile, planemaker Boeing has built a cryogenic fuel tank for space launches that it said could eventually store liquid hydrogen on commercial aircraft.

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Aviation giants aren’t alone in the effort to use hydrogen for jet fuel. The startups Universal Hydrogen and ZeroAvia are developing propulsion systems with hydrogen fuel cells, and both companies are preparing to flight-test their technology in turboprop planes from airports in Washington state. 

The slate of hydrogen initiatives comes as regulators, climate scientists and airline customers are paying closer attention to the hefty climate impacts of flying. Commercial air travel accounts for about 2.5 percent of global greenhouse gas emissions every year, and those emissions are expected to soar in the coming decades — unless companies change how they fuel and operate aircraft. 

As a hard-to-decarbonize sector…we shouldn’t be counting out any potential solution,” Amelia DeLuca, Delta’s vice president of sustainability, told Canary Media. Everything is on the table right now.”

Delta’s hydrogen plane push is a very meaningful” early step for U.S. aviation

Delta’s partnership with Airbus makes it the first U.S. airline to work with the European planemaker on hydrogen aviation. Last fall, Airbus unveiled three ZEROe” concept planes that burn liquid hydrogen in combustion engines, including a small passenger jet that Airbus claims could enter service in 2035.

An illustration of Airbus' A380 demonstrator that will test hydrogen propulsion in a combustion engine (Airbus)

The collaboration doesn’t entail any financial investment or agreement to purchase planes on Delta’s part, DeLuca said. Instead, the Atlanta-based airline will provide information and offer feedback on operational requirements such as flight range and refueling time, plus infrastructure needs at airports. The idea is to help Airbus design a hydrogen-powered aircraft that airlines can and want to fly, while also assessing broader challenges around scaling hydrogen production from renewables and bringing supplies to airports nationwide.

Delta’s participation, while still early, is a very meaningful” development for the future of hydrogen-powered flying, said Jayant Mukhopadhaya, an aerospace engineer and researcher at the International Council on Clean Transportation (ICCT). He said the fact that Delta is a U.S. company is particularly significant, in part because the United States accounts for more passenger air travel than any other country except China. 

It’s also noteworthy because of America’s potential to build enough solar, wind and renewable energy projects to produce huge quantities of hydrogen. For that reason, in 2035, liquid green” hydrogen is projected to be about one-quarter cheaper to produce in the United States than in the European Union, another likely early market for hydrogen aircraft, ICCT researchers projected in a recent paper.

That makes a huge difference in operational costs and generally [in] the economic case for green hydrogen,” Mukhopadhaya said.

A chart comparing current and projected future prices of fossil jet fuel, synthetic kerosene, and standard and green hydrogen
A price comparison of fossil jet fuel (Jet A); synthetic kerosene made from hydrogen and CO2 (e-kerosene); liquid hydrogen derived from natural gas (Blue LH2); and liquid hydrogen made using renewable electricity (Green LH2) in the EU and U.S. (ICCT)

Yet in both Europe and the U.S., hydrogen is projected to cost at least twice as much as fossil jet fuel without any policy interventions, such as a price being imposed on carbon dioxide emissions. Still, the more immediate challenge for aviation and other industries that could use hydrogen — such as maritime shipping, steelmaking and fertilizer production — is the wide gap between current supply and potential demand.

Today, the world produces around 70 million metric tons of hydrogen, the majority of which is made using natural gas via a process that emits carbon dioxide. So-called green” hydrogen is produced by using renewable electricity to power electrolyzers, which split water molecules into hydrogen and oxygen. 

About 0.3 gigawatts of electrolyzers are currently powered by renewables worldwide. For hydrogen to play a role in decarbonizing global industries, countries will need to build about 850 gigawatts of electrolyzers within the next eight years, according to the International Energy Agency.

One way to solve another hydrogen aviation challenge? Fuel capsules

Beyond boosting supplies, another major hurdle for hydrogen aviation is getting the fuel to airports and inside of planes, whether by using traditional pipeline networks and refueling hoses or — as Universal Hydrogen proposes — via lightweight, portable capsules.

Along with hydrogen planes, the Los Angeles–based startup is developing hydrogen storage capsules that would allow companies to collect the fuel from electrolyzer plants, move the capsules by freight truck or train, and then deposit the hydrogen pods directly into an aircraft’s body using a forklift. Co-founder Jon Gordon likened the capsules to refillable propane tanks for outdoor grills or the CO2 canisters that SodaStream devices use to make sparkling water.

We tried to remove all the excuses [around] hydrogen aviation, [including] that there’s no infrastructure,” he said. Gordon is one of several former Airbus employees now with Universal Hydrogen, including the startup’s CEO Paul Eremenko, who was previously Airbus’ chief technology officer.

Universal Hydrogen announced this month that it will build a $254 million manufacturing hub in Albuquerque, New Mexico. Starting in 2024, the company plans to produce both composite capsules for gaseous hydrogen, which can be used in fuel-cell powertrains, and cryogenic pods for liquid hydrogen, which can be burned in combustion engines.

A large experimental plane engine with a spinning propellor is demonstrated while sitting on a cargo truck
Universal Hydrogen's 1 MW fuel-cell powertrain is shown at the startup's facility at the Hawthorne Municipal Airport near Los Angeles. (Universal Hydrogen)

The startup also recently built a 1-megawatt fuel-cell powertrain that engineers are installing in a 40-passenger turboprop plane. Test flights are expected to start in September from an airport in Moses Lake, Washington. Some 200 miles to the west, just outside Seattle, the company ZeroAvia is preparing to retrofit its own turboprop plane in partnership with Alaska Airlines.

Universal Hydrogen aims to have small, hydrogen-powered passenger jets flying regional routes in the U.S. as early as 2025. That’s 10 years sooner than when Airbus plans to launch its first commercial hydrogen jet. Boeing, which remains more skeptical about the advent of hydrogen aviation, has said it doesn’t expect such aircraft to enter service before 2050.

What we view ourselves as doing in the industry is proving to Airbus and Boeing that hydrogen aviation is possible,” Gordon said. 

Airlines can act now to curb the climate toll of flying 

Still, airlines like Delta have more immediate options to begin curbing emissions than waiting for hydrogen aircraft to take flight.

In 2020, Delta retired more than 200 older aircraft and replaced them with planes that are 25 percent more fuel-efficient per seat-mile than their predecessors. The company also adjusts how planes fly and how cargo is distributed to minimize an aircraft’s fuel use. Just like if you’re driving a car, there are ways to fly an airplane more efficiently,” Delta’s DeLuca said.

Across U.S. commercial airlines, fuel efficiency improved by 1.5 percent per year between 2005 and 2019, which helped dampen growth in fuel consumption, a separate ICCT analysis found.

Airlines are also starting to blend their fossil jet fuel with small amounts of what are called sustainable aviation fuels,” or SAFs, which today are mainly made from used cooking oils and discarded animal fats. Although such fuels aren’t entirely emissions-free, when made from waste materials, SAFs have the potential to start curbing carbon dioxide emissions from existing aircraft and fuel infrastructure.

Delta aims to boost its SAF consumption from just 1 million gallons in 2022 to 400 million gallons by 2030. Meeting that lofty goal will depend on aviation fuel producers and state and federal agencies working together to dramatically increase SAF supplies across the country.

Sustainable aviation fuel is definitely what needs to happen now — and needs to happen fast,” DeLuca said. At the same time, the industry should work to develop technologies that can fuel airplanes in years to come. 

Green hydrogen will be part of our long-term solution,” she added.

Maria Gallucci is a clean energy reporter at Canary Media, where she covers hard-to-decarbonize sectors and efforts to make the energy transition more affordable and equitable.