ZeroAvia's Hydrogen-Electric Powertrain, the Fuel Cell That Makes Its Own Electricity, and the Dornier Two Twenty-Eight Flying on Water Vapor

A hydrogen-electric powertrain doesn’t burn anything. It uses a fuel cell to combine hydrogen with oxygen from the air, producing electricity to spin a propeller and emitting only water vapor and warm air. The company furthest along is ZeroAvia, which flew a hydrogen-electric Dornier 228 testbed from Cotswold Airport in England in January 2023 - a real flight test, not a slide deck.

What Is a Hydrogen Fuel Cell, and How Does It Work?

The easiest way to understand a fuel cell is to compare it to the battery you already carry. In a battery, the chemistry is sealed inside. You charge it up, drain it down, and recharge it when it’s dead. The energy lives in the box.

A fuel cell is a battery you refuel instead of recharge. You feed hydrogen in one side and air in the other, and as long as you keep feeding it, it keeps making electricity. Run out, and you pump in more - in minutes, not hours.

The mechanism is genuinely elegant. Hydrogen gas flows in and, at a special membrane, each hydrogen atom is split into a proton and an electron. The proton slips through the membrane; the electron can’t, so it’s forced the long way around through a wire. Electrons flowing through a wire is electric current - that’s the whole trick.

On the far side, the protons and electrons meet oxygen from the air and combine into water. Hydrogen plus oxygen yields water and electricity. No combustion, no carbon - the exhaust is water vapor.

That electricity drives an electric motor, which spins the propeller. From the prop’s point of view this is an electric airplane: quiet, instant torque, far fewer moving parts than a turbine. It simply carries a power plant that makes electricity on demand from a hydrogen tank, instead of hauling a heavy battery pack.

Hydrogen Combustion vs. Hydrogen Fuel Cells: What’s the Difference?

People hear “hydrogen airplane” and blend two very different machines in their heads.

The first is a hydrogen combustion engine, where you burn hydrogen in something that looks a lot like a jet engine. Airbus has studied this path. Different fuel, but it’s still fire.

The second - the fuel cell - doesn’t burn anything. That’s the technology ZeroAvia is pushing hardest for real aircraft, and it’s the one worth understanding.

Why Fuel Cells Are More Efficient Than Turbines

Efficiency is where the fuel cell quietly wins. A gas turbine, on a good day, turns only about 30 to 40 percent of the fuel’s energy into useful shaft power. The rest leaves as heat and noise.

A fuel cell can convert roughly 50 to 60 percent of the hydrogen’s energy into electricity. It’s fundamentally better at extracting energy from the fuel because it skips the whole messy business of heat, expansion, and spinning turbine blades.

Why Hydrogen Instead of Batteries? The Energy Density Problem

The problem with battery airplanes was never the motor - electric motors are fantastic. The problem is energy density: how much usable energy you can pack into each pound you carry.

Jet fuel is spectacular at this. The best aviation battery packs hold something like 40 to 60 times less energy per pound than jet fuel. That’s why a pure-battery airplane can be wonderful for a trainer doing 45-minute hops and hopeless for a regional airliner that needs 300 miles plus reserves.

Hydrogen changes the math. By weight, it carries roughly three times the energy of jet fuel per pound. If you could carry hydrogen the way you carry avgas, the range problem would nearly evaporate.

The Catch: Storing Hydrogen Is a Volume Problem

Pilots know there’s always a catch, usually hiding in the word “weight” or “volume.” Here, it’s volume.

Hydrogen is the lightest element in the universe, which makes it incredibly fluffy. As a gas at room pressure, a useful amount would need a tank the size of a barn. So you have to do one of two hard things:

Compress it to enormous pressure - 5,000 to 10,000 psi - in heavy carbon-fiber tanks.
Liquefy it by chilling it to minus 423 degrees Fahrenheit and keeping it that cold in a flying thermos.

Neither is easy.

Gaseous vs. Liquid Hydrogen: The Biggest Fork in the Road

This split is the single biggest fork in the road for the whole technology.

Gaseous hydrogen is simpler and available now, but the tanks are heavy and bulky and limit range. Liquid hydrogen is where the real range lives, but keeping a cryogenic liquid stable on a bouncing airplane - through cold soaks at altitude and hot ramps in Phoenix - is a genuinely unsolved operational problem.

The physics works. What’s hard is the engineering: plumbing, boiloff, and safety. Those are the things that take years.

Who Is Building Hydrogen-Electric Aircraft? ZeroAvia and the Dornier 228

ZeroAvia, with operations in the United Kingdom and the United States and founded by Val Miftakhov, has done the thing that separates a real program from a slide deck: it flew.

Its testbed is a Dornier 228, a rugged 19-seat twin turboprop commuter. ZeroAvia pulled one of the two engines and replaced it with a hydrogen-electric powertrain - left engine conventional, right engine hydrogen-electric. In January 2023, out of Cotswold Airport in England, it flew.

Be honest about what that flight was. It wasn’t a full airliner crossing a mountain range. It was a testbed running on one hydrogen-electric engine and one conventional engine, on a compressed gaseous hydrogen system, on relatively short flights. That’s exactly how a responsible flight-test program looks: keep a known-good engine on the other wing and expand the envelope one careful flight at a time.

The ZA600 and ZA2000: ZeroAvia’s Roadmap

ZeroAvia’s first product is a powertrain called the ZA600, aimed at the 9-to-19-seat commuter class - the little airplanes flying routes the big jets ignore.

On the drawing board is the larger ZA2000, aimed at 40-to-80-seat regional turboprops, the ATR and Dash 8 world. The strategy is to start small, where energy demands are survivable, and scale up as tanks and fuel cells mature.

ZeroAvia isn’t alone. Universal Hydrogen flew a larger Dash 8 hydrogen-electric testbed before running into financial trouble - a lesson in itself. Airbus has its ZEROe program studying hydrogen, though it has publicly stretched its timelines. Underneath all of it sits a real ecosystem of fuel cell, motor, and tank suppliers.

The Honest Ledger: Pros and Cons of Hydrogen-Electric Flight

The promise:

Zero carbon at the airplane - the exhaust is water. If the hydrogen itself is made cleanly with renewable electricity (green hydrogen), you get genuinely low-carbon flight.
Quiet operation, because an electric motor and propeller make a fraction of a turbine’s noise.
Fewer moving parts, which could mean lower maintenance over time.
Fast refueling - minutes, not hours - which pure-battery airplanes will never match.

The problems, given real weight:

Clean hydrogen is hard and expensive today. Most hydrogen now comes from natural gas, which produces carbon dioxide. Fly on that and you’ve just moved the carbon to a factory. Green hydrogen exists but is costly and scarce.
Airport infrastructure doesn’t exist. There’s no hydrogen pipeline network at your local field. You’d need production or delivery, storage, and refueling gear at every airport - a chicken-and-egg problem measured in billions of dollars and years.
Cryogenic liquid hydrogen is unproven at scale. Anything bigger than a commuter almost certainly needs liquid hydrogen for useful range, and keeping it stable in daily airline service hasn’t been demonstrated.
Certification is written for kerosene. The FAA and its European counterpart have decades of rules built around burning jet fuel. High-pressure tanks, cryogenic systems, fuel cells, and high-voltage architecture all need new standards written nearly from scratch - a paperwork-and-precedent problem that can move slower than the engineering.

When Will Hydrogen Aircraft Actually Fly Passengers?

Small 9-to-19-seat commuter aircraft flying revenue routes on hydrogen-electric power, in limited markets, in the late 2020s, is plausible. ZeroAvia is targeting the back half of this decade for the ZA600 to enter service. Aerospace timelines slip, but the class of airplane fits: short routes, modest energy needs, gaseous hydrogen you can handle today.

The bigger 40-to-80-seat regional airliners are a 2030s story, dependent on liquid hydrogen maturing and infrastructure arriving.

The single-aisle long-haul jet you take to visit family? Hydrogen is a very long shot for that mission for a very long time. Storing enough hydrogen for long-haul is brutal - don’t believe anyone who promises it soon.

The most useful way to file all of this: battery-electric owns the short end (trainers, short hops, local flying), hydrogen-electric is the most credible bet for the middle (regional and commuter routes), and kerosene - likely blended with sustainable aviation fuel - will own long-haul for a long time. It’s not one technology winning; it’s the right tool for each mission.

What makes the hydrogen story worth watching isn’t a promise of a clean sky next year. It’s that someone put a fuel cell on the wing of a real Dornier 228, kept a known-good engine on the other side, actually flew it, and described honestly what it was. This isn’t science fiction - it’s a plumbing problem, and plumbing problems get solved.

Key Takeaways

A hydrogen fuel cell generates electricity by combining hydrogen with oxygen from the air, emitting only water vapor - no combustion and no carbon at the aircraft.
Fuel cells convert about 50–60% of fuel energy to electricity versus a turbine’s 30–40%, and hydrogen holds roughly 3× the energy per pound of jet fuel.
The core obstacle is volume: hydrogen must be compressed to 5,000–10,000 psi or liquefied at −423°F, with liquid storage still operationally unproven.
ZeroAvia flew a hydrogen-electric Dornier 228 from Cotswold Airport in January 2023, targeting the ZA600 (9–19 seats) for service in the late 2020s and the ZA2000 (40–80 seats) in the 2030s.
The biggest hurdles now are clean hydrogen supply, airport infrastructure, and certification - engineering and logistics problems, not physics.