ZeroAvia, the Dornier Two Twenty-Eight Testbed, and the Hydrogen-Electric Powertrain Targeting Regional Routes That Batteries Cannot Reach

ZeroAvia is developing a hydrogen-electric powertrain called the ZA600 designed to replace turboprop engines on commuter aircraft flying routes of up to 300 miles. The company flew a modified Dornier 228 on hydrogen-electric power for the first time in January 2023 at Cotswold Airport in England. The physics behind the approach is sound - the challenge now is certification, infrastructure, and green hydrogen supply.

Why Batteries Cannot Power Regional Commuter Routes

The electric aviation conversation has been dominated by lithium-ion for nearly a decade, and the results in light aircraft are real. The Pipistrel Velis Electro, the first type-certificated electric aircraft in Europe under EASA, can fly training circuits for about an hour. That works for pattern work at a flight school.

It does not work for a nine-seat commuter aircraft flying a 200-mile route with meaningful payload. The best lithium-ion packs available today store roughly 200 to 250 watt-hours per kilogram of total pack weight. Size a battery for that mission and you give up passengers, cargo, reserves, or all three.

Jet-A carries about 12,000 Wh/kg. Even accounting for the efficiency advantage of electric motors over combustion, fossil fuel still carries vastly more usable energy per pound than any battery buildable today. The fundamental chemistry of lithium-ion is close enough to its theoretical maximum that a step-change improvement is not on a near-term horizon.

How Hydrogen-Electric Propulsion Works

Compressed hydrogen gas contains about 33,000 Wh/kg of hydrogen. Run it through a fuel cell at typical efficiency - 50 to 60 percent - and you get roughly 16,000 to 20,000 Wh of usable electrical energy per kilogram of fuel. Even after accounting for the weight of the fuel cell stack, high-pressure tanks, thermal management system, and power electronics, hydrogen-electric propulsion comes out substantially ahead of batteries on any route where range and payload both matter.

The system itself works like this: hydrogen stored in high-pressure tanks (or as cryogenic liquid) feeds into a fuel cell stack. At the anode, hydrogen reacts electrochemically with oxygen drawn from outside air at the cathode, producing electricity, heat, and water vapor. No combustion. No turbine. No hot section. The direct current output drives an electric motor, which turns a conventional propeller.

That drivetrain simplicity carries a maintenance argument. A turboprop like the Pratt & Whitney Canada PT6 - which powers more aircraft worldwide than probably any other turbine - has thousands of parts spinning at extreme temperatures, with inspection cycles running from several hundred to several thousand hours per component. ZeroAvia positions the fuel cell powertrain as potentially far cheaper to maintain over time, though they correctly frame this as a potential advantage rather than a proven one. The flight hours to prove maintenance economics in service do not yet exist.

The ZA600 Powertrain and Dornier 228 Test Program

ZeroAvia was founded by physicist and entrepreneur Val Miftakhov in 2018. The company went hydrogen-electric from day one rather than following the battery path, and its first commercial powertrain program reflects that focus.

The ZA600 delivers 600 kilowatts of continuous power - equivalent to roughly 800 shaft horsepower, compared to about 1,270 shaft horsepower for a Pratt & Whitney Canada PT6A-67P. That output is sufficient for a single-engine installation on a commuter-class aircraft in the 9 to 19 seat range, or one engine in a twin-engine configuration.

The test airframe is the Dornier 228, a 19-seat twin turboprop that has been in production and service since the early 1980s. It flies scheduled service across the Scottish Highlands and Islands, in Norway, East Africa, and across parts of Asia - exactly the route types ZeroAvia is targeting. On January 2023, ZeroAvia flew a Dornier 228 with one turboprop replaced by the ZA600 at Cotswold Airport in England. The first flight lasted approximately eight minutes.

Eight minutes sounds like a student pilot’s first lesson. For a novel propulsion system, it is the right place to start. A maiden flight answers integration questions, not range questions: Does the fuel cell hold stable voltage under sudden power demand changes? Does the motor respond to throttle inputs with the latency the flight control laws expect? Does the hydrogen feed system behave predictably across the power cycle? Is thermal management keeping the stack in its operating window? Is the high-pressure plumbing holding up to vibration?

That data fed into subsequent testing at ZeroAvia’s facility in Hollister, California. The ZA600 program also builds on earlier UK development work under the HyFlyer One and HyFlyer Two programs, which used a Piper Malibu to develop and validate the fuel cell stack at lower power levels before scaling to the Dornier. That methodical progression - small airframe to commuter scale - is the approach that builds genuine engineering confidence.

What Flying a Hydrogen-Electric Aircraft Is Actually Like

Pilots who have flown electric propulsion testbeds describe the experience as unusually smooth and quiet. The turbine whine is gone. The vibration character is different. The motor does not have the same mechanical feel as a reciprocating or turbine engine. Some pilots find the silence disorienting initially.

Throttle response from an electric motor is near-instantaneous compared to a turbine, which has spool time. That changes power management on approach and during go-arounds. The power-lever dynamics are different, and pilot training curricula for hydrogen-electric aircraft will need to account for it. This is not a harder aircraft to fly - it is a different aircraft to fly.

Why Hydrogen Refueling Beats Battery Charging for Scheduled Operations

Commuter operations run tight turnarounds. Aircraft sit at the gate for 20 to 30 minutes between flights. Even aggressive fast-charging configurations can take 30 minutes to an hour to bring a large battery pack to usable charge levels, and repeated fast-charging degrades battery life over time.

Compressed gaseous hydrogen can be dispensed at speeds comparable to conventional jet fuel. Liquid hydrogen is faster still. The turnaround time penalty for hydrogen refueling is far smaller than for battery charging, which makes hydrogen-electric operationally compatible with scheduled commuter service in a way that battery-electric is not.

Where the Real Challenges Are: Infrastructure and Green Hydrogen

The honest challenge for hydrogen aviation is not the physics - it is the supply chain. Hydrogen production, compression or liquefaction, transport to airports, ground storage, and dispensing equipment does not exist at most airports. Even a certified ZA600 cannot enter commercial service until someone builds hydrogen fueling capability at every airport on the route network.

The chicken-and-egg problem is real: operators will not commit aircraft without fuel, and airport authorities will not invest in infrastructure without committed aircraft operations to justify it.

Some airports on ZeroAvia’s target route map are approaching this differently. The Orkney Islands in Scotland have surplus capacity from wind energy generation. The concept being explored there is on-site green hydrogen production using electrolysis powered by that renewable surplus - make hydrogen locally, compress it, dispense it to aircraft. That removes the transport problem and, if the electricity source is genuinely renewable, produces hydrogen with near-zero carbon footprint.

The distinction between green and gray hydrogen matters enormously. Gray hydrogen - the majority of current hydrogen production - comes from natural gas through steam methane reforming and carries a substantial carbon footprint, comparable in some analyses to fossil fuel combustion. The environmental case for hydrogen aviation depends entirely on green hydrogen, and green hydrogen at scale is not cheap or widely available today.

The cost of green hydrogen is falling as electrolyzer capacity grows and renewable electricity costs decline. But at current prices, green hydrogen for aviation is significantly more expensive per energy unit than jet fuel. That economics gap requires either falling costs, carbon pricing, or regulatory mandate - or some combination of all three - to make the business case work for operators without subsidy.

The Certification Timeline and Commercial Commitments

The FAA and EASA are both developing frameworks for hydrogen aviation certification, and ZeroAvia has been engaged with both authorities throughout the program. Detailed regulatory guidance for certifying a hydrogen-electric propulsion system in a type-certificated airframe does not yet exist in a form that would allow a straightforward certification campaign to proceed. Writing novel propulsion certification guidance takes years.

ZeroAvia originally targeted entry into service for the ZA600 in the 2025 to 2026 timeframe. That target has proven difficult to hold. Certification work and infrastructure development have paced more slowly than the engineering program.

The airline commitments the company holds are credible. Alaska Airlines is an investor. United Airlines signed a conditional purchase agreement for 100 aircraft. International Airlines Group - parent company of British Airways and Iberia - signed a purchase agreement for 10 aircraft. These are carriers that conduct commercial due diligence before attaching their names to anything. A conditional purchase agreement, however, is an option, not a delivery order. The aviation industry has signed conditional agreements for technology that later ran into development problems, funding shortfalls, or certification delays. The gap between a signed agreement and an aircraft in revenue service deserves honest acknowledgment.

ZeroAvia’s longer-range ambition is the ZA2000 - 2 megawatts of continuous power, targeting aircraft like the ATR 72 and the Bombardier Dash 8 Q400, which carry 50 to 70 passengers on routes forming the core of regional air service in Europe, Canada, Scandinavia, and parts of the United States. Ground and flight testing at that power level is still ahead, and the timeline there is further out than the ZA600.

Who Else Is Working on Hydrogen Aviation

ZeroAvia is the most advanced Western hydrogen-electric program targeting near-term commercial certification in the commuter aircraft class, but it is not operating in isolation.

H2Fly, a German company, has been testing hydrogen fuel cell-powered aircraft and has accumulated meaningful flight hours on their testbed program. Airbus has its ZEROe program exploring hydrogen propulsion architectures, though at a much larger aircraft scale with a longer development horizon. Universal Hydrogen was developing modular hydrogen capsule retrofits for regional turboprops before running into capital difficulties in 2024.

The broader hydrogen aviation ecosystem has multiple serious participants and has attracted genuine government interest in Europe, the United Kingdom, and the United States.

Key Takeaways

• Batteries cannot close the energy density gap for 9-to-19-seat commuter routes - hydrogen-electric is the only near-term zero-emission candidate for that mission
• ZeroAvia completed the first hydrogen-electric flight of a Dornier 228 in January 2023; the ZA600 powertrain targets entry into service after a certification timeline that has slipped from the original 2025–2026 window
• Hydrogen refueling is operationally compatible with tight commuter turnarounds in a way that battery charging is not
• The environmental benefit depends entirely on green hydrogen - gray hydrogen, made from natural gas, undercuts the carbon case
• The infrastructure chicken-and-egg problem is the most immediate operational barrier; some target airports, including Orkney, are exploring on-site renewable hydrogen production as a solution
• Watch certification milestones, hydrogen infrastructure investment at target airports, and the green hydrogen cost curve - these are the indicators that will determine whether commercial service follows the engineering progress