ZeroAvia and the hydrogen-electric powertrain that wants to replace jet fuel without waiting for better batteries

ZeroAvia is developing a hydrogen-electric powertrain designed to replace conventional turboprop engines on regional aircraft, eliminating in-flight carbon emissions without requiring new airframes, new runways, or new pilot type ratings. The California-based startup, founded in 2018 by physicist and entrepreneur Val Miftakhov, has already flight-tested the technology on a 19-seat Dornier 228 and is targeting commercial entry by the late 2020s. The core proposition: swap what burns inside the engine, keep everything else.

How Does a Hydrogen Fuel Cell Powertrain Work?

A hydrogen fuel cell is neither a battery nor a combustion engine. Compressed hydrogen gas enters one side of a fuel cell stack, ambient air enters the other, and an electrochemical reaction produces electricity and water. That electricity drives an electric motor, which turns the propeller. There is no combustion, no carbon dioxide, and no nitrogen oxides. The only exhaust product is water vapor.

The thermodynamic efficiency of this process is roughly 50 to 60 percent, compared to the 30 to 35 percent thermal efficiency of a typical turboprop gas turbine. That efficiency gap is one of the core reasons aerospace engineers are taking hydrogen fuel cells seriously.

Why Hydrogen Instead of Batteries?

Energy density is the deciding factor. The best lithium-ion cells available today store approximately 250 watt-hours per kilogram. Jet-A stores about 12,000 watt-hours per kilogram. Batteries are nearly 50 times worse by weight, which is why the Pipistrel Velis Electro — an impressive achievement in its own right — flies for roughly 50 minutes.

Compressed hydrogen gas at 700 bar stores approximately 33,000 watt-hours per kilogram of the hydrogen itself. After accounting for tank weight and the fuel cell stack, the full system delivers roughly 1,500 to 2,000 watt-hours per kilogram. That is six to eight times better than batteries — not as energy-dense as kerosene, but sufficient to serve short-haul turboprop routes.

What Has ZeroAvia Actually Flown?

ZeroAvia’s flagship program is the ZA-600, a 600-kilowatt hydrogen-electric powertrain designed to replace one turboprop engine on a 19-seat regional aircraft. The development milestones so far:

2020: Completed what ZeroAvia called the world’s first hydrogen fuel cell powered flight of a commercial-grade aircraft, using a modified Piper Malibu as a testbed.
January 2023: Flew a 19-seat Dornier 228 twin with the left engine replaced by the hydrogen-electric system. The right engine remained conventional as a safety backup. The flight took place at Cotswold Airport in the United Kingdom.

What Routes Could Hydrogen-Electric Aircraft Serve?

ZeroAvia’s publicly stated target for the ZA-600 is flights of roughly 300 nautical miles with 19 passengers. That range covers a significant portion of regional aviation: island hopping in the Pacific Northwest, milk runs in Alaska, Scottish Highlands routes, and Norwegian coastal flights. These are missions where turboprops already dominate and where hydrogen economics could become competitive as fuel costs decline.

How Do the Operating Economics Compare?

A typical turboprop engine on a 19-seat aircraft burns roughly 40 to 50 gallons of Jet-A per hour. At $6 per gallon, that is approximately $300 per flight hour in fuel alone. ZeroAvia claims their hydrogen system could cut fuel costs by roughly 50 percent at scale.

Maintenance savings may be even more significant. A fuel cell stack has no combustion, no turbine blades, and no hot section inspections. Electric motors have one moving part. For regional turboprop operators running thin routes that airlines routinely threaten to cut, those combined savings could fundamentally change the economics.

What Are the Major Obstacles?

Hydrogen Storage

700-bar compressed hydrogen tanks are heavy, bulky, and expensive. They consume more volume than a kerosene tank carrying equivalent energy. On a 19-seat aircraft, the tanks eat into cargo space and potentially reduce passenger capacity. Carbon fiber composite tanks are improving annually, but this remains a hard engineering constraint.

Airport Infrastructure

Virtually zero hydrogen fueling infrastructure exists at airports today. Deployment requires delivery trucks, storage facilities, high-pressure dispensing equipment, and entirely new safety protocols for ground crews. Compare this to sustainable aviation fuel, which uses existing trucks, tanks, and fuel nozzles already on the ramp. Infrastructure inertia is a powerful force, and building out hydrogen fueling at scale is a multi-billion-dollar undertaking.

Certification

Neither the FAA nor EASA has ever certified a hydrogen fuel cell powertrain for commercial passenger service. ZeroAvia is pursuing a supplemental type certificate pathway, proving their powertrain can safely replace an existing engine on an already-certified airframe. EASA and the UK Civil Aviation Authority have been publicly engaged, but novel propulsion certification is not fast. ZeroAvia has discussed commercial entry around 2027 or 2028, but certification timelines in aviation almost always slip, especially for technologies this novel.

Fuel Cell Durability

ZeroAvia uses proton exchange membrane (PEM) fuel cells, which degrade over time as membranes wear and catalyst layers lose surface area. In automotive applications, Toyota has achieved fuel cell lifetimes of roughly 30,000 hours in its Mirai vehicles. Aviation demands similar or better durability in a far harsher operating environment — temperature swings, altitude changes, vibration, and highly variable power demands. ZeroAvia has published limited durability data, making this an area worth watching closely.

The Green Hydrogen Problem

Most hydrogen produced today comes from steam reforming natural gas — so-called gray hydrogen — which is not carbon-neutral. The aviation hydrogen vision depends on green hydrogen, produced by electrolysis of water using renewable electricity. Green hydrogen currently costs roughly $4 to $8 per kilogram. The U.S. Department of Energy’s Hydrogen Shot initiative targets $1 per kilogram by 2030. If that target is approached, the fuel economics shift dramatically in hydrogen’s favor.

Who Is Investing in ZeroAvia?

ZeroAvia has raised over $150 million from strategic investors including Amazon’s Climate Pledge Fund, Bill Gates’s Breakthrough Energy Ventures, British Airways parent company IAG, and Airbus. These are organizations with deep understanding of aviation economics, not speculative venture funds.

What Happened to the Competition?

Universal Hydrogen, a competitor pursuing a modular hydrogen capsule approach, shut down in 2024 after failing to secure additional funding — a stark reminder that this technology space is genuinely difficult.

Airbus continues its own ZEROe program, exploring hydrogen combustion and hydrogen fuel cell architectures for larger aircraft with a target entry into service around 2035. The key difference: Airbus is designing clean-sheet aircraft for 100-plus seats, while ZeroAvia is retrofitting existing regional planes on a shorter timeline.

Where Hydrogen Fits in Aviation’s Energy Future

The future of aircraft propulsion is likely a spectrum of technologies matched to mission profiles:

Batteries for flight training and very short hops
Hydrogen fuel cells for regional routes under 300 nautical miles
Sustainable aviation fuel for medium- and long-haul flights
Hydrogen combustion potentially for large jets, eventually

Regulatory tailwinds are building. The European Union’s Fit for 55 package and ICAO’s long-term goal of net-zero carbon emissions by 2050 are creating policy pressure that favors zero-emission technologies. ZeroAvia is positioned to catch that wave in the regional segment, where the engineering logic is sound even as execution risk remains real.

Key Takeaways

ZeroAvia’s hydrogen fuel cell powertrain offers six to eight times the energy density of batteries at the system level, making 300-nautical-mile regional flights feasible with zero in-flight emissions.
The January 2023 Dornier 228 flight demonstrated the technology on a commercial-size airframe, but FAA and EASA certification for passenger service has never been done for this propulsion type.
Green hydrogen cost must fall dramatically — from today’s $4–$8/kg toward the DOE’s $1/kg target — for the economics to fully compete with Jet-A.
Airport hydrogen infrastructure is essentially nonexistent and represents a multi-billion-dollar buildout challenge that sustainable aviation fuel does not face.
Strategic backing from Amazon, Breakthrough Energy, IAG, and Airbus signals serious institutional confidence, but Universal Hydrogen’s 2024 closure shows the path is not guaranteed.