Boarding Next: Net Zero Flights
Hydrogen-electric and SAF as pathways to decarbonize aviation
By Scott Rhode

lying is magical in a way that a century of air travel has not quite diminished. Pasha Saleh, head of corporate development for Alaska Airlines, appreciates the prestige.

“I started off as a regional pilot for almost a decade, so the idea of regional aviation is really exciting,” Saleh says. “The vast majority of traffic in America goes to something like 300 or 400 airports, but there are 5,000 airports in America. If you could bring those back to life again with sustainable flights, I personally get really excited about that.”

The magic of aviation comes at a price that makes it, at present, unsustainable. A jet flight, depending on distance, might emit as much greenhouse gas per traveler as the entire annual carbon footprint of a single person living in more than one-fourth of the world’s countries. Frequent flyers rack up double, triple, or ten times the emissions.

A “flight shaming” movement has arisen to counteract travel-related greenhouse gasses. “Public sentiment is strongly moving that way,” Saleh says, pointing to laws in Europe banning domestic air travel where trains are an option.

Decarbonizing aviation is not easy. Hydrocarbons made flight possible, thanks to the energy density of kerosene. “It’s just sort of a magic fuel for what we do,” says Saleh. “Jet fuel was the perfect fuel for what we used it for, notwithstanding all the detrimental environmental effects that we’re now realizing.”

Recognizing those effects, Alaska Airlines is pursuing a five-part path toward net zero emissions by 2040. The last resort, Saleh says, would be carbon offsets, or paying for credits to account for emissions that can’t be engineered out of the system. Before that, the company is modernizing its fleet to the Boeing 737 MAX and streamlining operations through speedier baggage loading or by training pilots to taxi on single engines.

Kicking the fossil fuel habit is another pathway, and the fifth is investing in novel propulsion, such as a hydrogen-electric powertrain.

Hero of Zero
Jet propulsion is where the president of Ravn Alaska’s parent company got his start. Tom Hsieh worked on the Galileo and Cassini missions to Jupiter and Saturn at the Jet Propulsion Laboratory. Later, he was an engineer at Earthlink, one of the first billion-dollar dot-com IPOs on the Nasdaq stock market.

In 2020, Hsieh co-founded FLOAT, a startup airline in Southern California focused on operating the new generation of electric aircraft. “Our intent was to start with conventional aircraft, build a ridership, build a business model, and then upgrade the technology as that grew,” Hsieh recalls. When COVID-19 disrupted the travel industry, FLOAT pivoted to operating an existing fleet by acquiring Ravn Alaska at a bankruptcy auction. Now Ravn Alaska is becoming a vehicle for electrifying aviation.

Ravn Alaska has pre-ordered thirty kits to retrofit its fleet of De Havilland Dash 8 turboprops: ten of the forty-seat 100 series and one of the fifty-six-seat 300s. London-based startup ZeroAvia is developing the kits that combine hydrogen fuel cells and electric motors.

In exchange for an ownership stake in ZeroAvia, Alaska Airlines supplied an airframe for testing: a Bombardier Q400 (a type of De Havilland Dash 8) retired from its regional fleet.
In exchange for an ownership stake in ZeroAvia, Alaska Airlines supplied an airframe for testing: a Bombardier Q400 (a type of De Havilland Dash 8) retired from its regional fleet.

Alaska Airlines

“We want to be at the forefront of adopting zero-emission aviation once FAA-certified technologies come to market,” says Ravn Alaska CEO Rob McKinney. “ZeroAvia is making great strides to bringing hydrogen-electric propulsion to Alaskan skies, and we’re looking forward to working together to realize green flight.”

ZeroAvia has a target date of 2026 to deliver its ZA2000 powertrain. The system is designed to propel a 100-seat airliner on flights up to 700 nautical miles. That would serve Ravn Alaska’s needs for the two-hour connection between Anchorage and the Yukon River village of St. Mary’s, for example.

“Alaska represents the challenge facing the aviation industry writ large,” says ZeroAvia founder and CEO Val Miftakhov. “With its ample renewable energy supply and network of airfields, the state is the perfect place for some of the world’s earliest hydrogen-electric, zero-emission routes.”

ZeroAvia is also getting startup support from Launch Alaska, a nonprofit accelerator for climate technology innovations. Hsieh happens to be a Launch Alaska trustee, “Matchmaking mostly new technologies and end users, matching them with subsidies and federal grants, et cetera,” he says. “We see a future in the aviation space using renewable energy, and we want to be a part of that.”

Flying on Hydrogen
In January, ZeroAvia successfully tested a hydrogen-electric Dornier 228. ZeroAvia uses grid power to make hydrogen by electrolysis of water. The resulting hydrogen is stored in the plane, and proton exchange membrane fuel cells convert the hydrogen into electricity to drive the Dornier 228’s propellers. The nineteen-passenger utility aircraft has a range of about 300 nautical miles with a 600-kW powertrain. A retrofitted Dash 8 will have three times the power at 1.8 MW.

This summer, the modified Dornier 228 is flying its first point-to-point route, a step up from test flights that land where they originated. Georgy Egorov, chief investment officer for ZeroAvia, says the company aims to fly a modified Dash 8 by the end of 2024.

The progress and promise convinced Alaska Airlines to take an equity share in ZeroAvia. “They were the only people in the world who had flown an airplane on hydrogen,” says Saleh. “Yes, it was a smaller airplane, but they proved it could be done.”

ZeroAvia is not the only pioneer in zero-emission aviation. Saleh points to California-based Universal Hydrogen, which envisions a central electrolysis plant that would dispatch tanker trucks to airports nationwide. Contrast that with ZeroAvia’s concept of producing hydrogen near airports. “Too soon to tell which is the right approach, or maybe it’ll be both,” says Saleh, “but we cast our lot with ZeroAvia mainly because of that pragmatic approach.”

Test flights so far have used gaseous hydrogen, but future aircraft will use super-chilled liquid hydrogen, the same propellant that filled the space shuttle’s enormous external tank. For ZeroAvia to succeed, ground crews at every regional airport in Alaska—from Ralph Wien Memorial in Kotzebue to Merle K (Mudhole) Smith in Cordova—would need to handle, essentially, rocket fuel.

ZeroAvia is realistic about the difficulties, and Saleh says Alaska Airlines bought into ZeroAvia thanks to the startup’s honesty. Leadership was impressed when ZeroAvia admitted that a certain technology wasn’t ready and then, a year later, came back with a real solution. “They’re not just trying to sell us something,” he says.

Something Out of Nothing
The Dash 8 retrofit kits that ZeroAvia aims to sell, Alaska Airlines couldn’t buy anyway. Sister carrier Horizon Air flew its last Dash 8 in January; since then, Horizon only flies Embraer E175 jets. For the sake of crew efficiency, Alaska Air Group sold its thirty-two Dash 8 turboprops.

One of those airframes is now ZeroAvia’s testbed. Alaska Airlines’ ownership stake in the startup was the purchase price for the plane. Technically, it’s a version of the Dash 8 known as the Bombardier Q400, a larger variant of the Q300 in Ravn’s fleet.

“This is sort of the perfect size, where it’s definitely a stretch goal,” says Saleh. “It’s not easy for them to go from nineteen-seater to seventy-six, but if that can be done… Yeah, maybe they can do that, and then we would be interested.”

ZeroAvia might get rich selling hydrogen-electric powertrains for Dash 8s, and Alaska Airlines would share in that profit—even if it never uses the technology itself. The company’s experience with Dash 8s has value for ZeroAvia’s development. “We have some insight, when you’re dramatically modifying it,” says Saleh. “How would you do that with an eye toward serviceability, being able to load it and unload it?”

Hands-on experience as a pilot is what Saleh brings to the airline’s sustainability initiatives. “Having walked in the shoes of the pilot, you sort of understand what we can achieve and what we can’t,” he says. “There’s a lot of mythical things out there that profess to have sustainability benefits, but even if they were to materialize, is this something you can practically use?”

Materializing something out of seemingly nothing must surely be mythical. That’s the reaction Ashwin Jadhav frequently hears about his company’s flagship project, E-Jet. As vice president of business development for Twelve, Jadhav must not only explain how the product works but that, yes, it really exists.

E-Jet is functionally the same as kerosene jet fuel except that, instead of being refined from petroleum, it’s synthesized from carbon dioxide and water. That is, with an input of electricity, exhaust gas is transmogrified back into combustible liquid. Presto!

“I mean, that would be the perfect solution,” says Saleh of recycling carbon from the air. So Alaska Airlines is backing Twelve, too, preordering E-Jet fuel.

“I’m very excited about that,” says Jadhav. “Alaska Airlines obviously is, you know, a leader in the sustainability space… They’ve given us the opportunity to go to market with their airplanes, and hopefully it’s a long-lasting partnership.”

Magic Words
The technologies that both Twelve and ZeroAvia are developing are in a category called Power-to-X, where electricity from whatever source (preferably renewable) drives a process that stores the energy in chemical form.

Twelve has other product lines that spin waste carbon dioxide—currently taken from flue gas at ethanol plants—into more valuable products, like feedstock for laundry detergent, plastic sunglass lenses, or auto parts. Jadhav says sustainable aviation fuel (SAF) is the most scalable market, so that is where the focus is. “From an economic perspective, there’s a lot of incentives out there that facilitate the fast scale-up,” he says.

The magic words that enable Twelve’s astonishing transmutation are “proprietary catalyst.” A reactor vessel splits carbon dioxide into carbon monoxide, which combines with hydrogen to form syngas, a common chemical feedstock. Via the century-old Fischer-Tropsch process, syngas becomes liquid hydrocarbon.

Test pilot Jon Killerby hugs ZeroAvia's vice president for Europe, Sergey Kiselev, to celebrate the successful test in January of a hydrogen-electric Dornier 228, a nineteen-seat utility plane.
Test pilot Jon Killerby hugs ZeroAvia’s vice president for Europe, Sergey Kiselev, to celebrate the successful test in January of a hydrogen-electric Dornier 228, a nineteen-seat utility plane.


ZeroAvia’s ground test rig, called HyperTruck, tests the HyperCore motor in May, as the company scales up to airliners with larger propellers.

Joe Nicholson | ZeroAvia

ZeroAvia's ground test rig, called HyperTruck, tests the HyperCore motor in May, as the company scales up to airliners with larger propellers.
E-Jet works in existing engines, no retrofits necessary. However, due to current regulations, Jadhav says test flights must blend it 50/50 with conventional fuel.

Construction is set to begin this year on a commercial-scale fuel plant at Moses Lake, Washington. Abundant hydropower enables Twelve to claim a 90 percent reduction in life-cycle carbon dioxide emissions compared to fossil fuel. “The reason we’re not at zero is because, within the process itself, there are still some emissions: we have to transport the fuel via truck to a blending facility, et cetera,” Jadhav explains.

Twelve takes its name from the atomic weight of carbon—six protons and six neutrons—and Jadhav says the company is trying to rehabilitate the element. “Whenever somebody thinks of carbon dioxide these days, it sounds like a slightly dirty word, right? Because of emissions and whatnot,” he says. “We want to be able to rewrite the story of carbon.”

The US Air Force helped write that story by backing a pilot project in 2021. The online retailer Shopify is also supporting Twelve by purchasing the green energy attributes of E-Jet, if not the fuel itself. Abu Dhabi-based Etihad Airways is another early customer, ready to use E-Jet when the Moses Lake gigafactory is operational sometime next year.

By that time, Alaska Airlines will also pump E-Jet into planes at Seattle-Tacoma International Airport. Flyers bound for Alaska will ride on fuel made from smokestack waste and Washington hydropower. “We hope that we can provide Alaska Airlines with millions and millions of gallons of fuel in the future,” says Jadhav, “not only to penetrate into the Alaska region but, you know, across their entire network.”

Capacity to Grow
Twelve is planning two more factory sites to open in 2025 and 2026. Might one be located at the other end of a Seattle-to-Alaska flight?

“Alaska is definitely being considered, specifically because there’s so much energy,” Jadhav says.

The “Air Crossroads of the World” in Anchorage is especially attractive because cargo flights can refuel midway between Asia and the Lower 48. “It’s easier to pass the incentives and costs down the supply chain to freight forwarders, so the [cargo] airlines are slightly more amenable; they have a bigger SAF appetite in general,” says Jadhav.

Jet fuel has long been refined in Nikiski, Valdez, and North Pole from local petroleum, but producing SAF would require an entirely different infrastructure. The electricity grid in the Anchorage area is largely powered by Cook Inlet natural gas, and it would be pointless to burn that resource simply to transfer its energy to airplanes.

Jadhav says Twelve would need a long-term supply of renewable energy, a surplus that could drive its chemical process. “The renewable energy grids that exist today are built for today; they’re not built for the kinds of power we need in 2040, in 2050. We’re very limited in what we’re seeing, from a capacity perspective, so that has to grow,” Jadhav says.

Furthermore, an E-Jet plant would be co-located with a carbon dioxide source, also not from burning fossil fuels. The exhaust is too impure for the chemistry, Jadhav explains, and it would wipe out E-Jet’s value as green energy.

Wisps of carbon dioxide are available in the surrounding air, but not enough for Twelve’s industrial process. Only a small portion comes from direct air capture, but Jadhav says that may increase as technology improves.

Meanwhile, hydrogen is readily available in water, so ZeroAvia has the advantage of raw material anywhere that Ravn Alaska flies.

“We’re hoping to start flying hydrogen aircraft in 2025,” Hsieh says. He then asks, “Where’s the hydrogen going to come from?” According to Hsieh, Ravn Alaska would like to see hydrogen made locally, but the resources to produce it haven’t been built yet.

Mutual Respect
The two approaches to decarbonizing aviation—ZeroAvia’s hydrogen-electric and Twelve’s SAF—might seem to be in competition. Neither company sees it that way, though.

“SAF, we like it because it can be implemented right now,” says ZeroAvia’s Egorov. “I have such respect for the SAF.” He notes that ZeroAvia is on a pathway to fly 100-seat airliners, but jumbo jets are beyond the technological horizon.

Meanwhile, SAF is a more mature technology with more obvious rewards. “When we sign our power purchase agreements with renewable electricity providers, we’re doing so for ten to twenty years,” Jadhav says. “I have the ability to give the airline a fixed price for the next ten years that is not linked to any index, it’s not linked to fossil fuel.”

Saleh agrees that longer flights will be chiefly decarbonized with SAF to reach the 2040 goal. “We have to use everything in our arsenal to be able to do that,” says Saleh. “Electric aviation is just one tool, but it only affects the regional subsidiary that we have.”

Further, there’s more to SAF than E-Jet; more progress has been made using biofuels made from forest residues or cooking oil. Twelve’s process is a step toward capturing carbon from the atmosphere. “That’s pure magic, super expensive,” Saleh says.

“We need all of these technologies to work together,” Jadhav says. “We [the industry] are throwing darts, in some ways, but a lot of these darts are interchangeable; the optimization of the darts is unknown yet.” He adds that certain technologies work better for different categories of aircraft. ZeroAvia, for instance, could retrofit small Cessnas that service Northern Alaska and Southeast, where SAF for jets is not the optimal solution.

“We’ll compete in 2050,” Jadhav says.