Hydrogen Aviation, HYSKY, and FEV Aerospace: Adapting Automotive Fuel Cell Technologies for Flight
- HYSKY Society
- 1 day ago
- 8 min read
HYSKY Monthly welcomed experts from FEV Aerospace who explored how decades of automotive fuel cell development are providing the foundation for a new generation of hydrogen-powered aircraft. In the presentation, From Automotive to Airborne: Adapting Hydrogen Fuel Cell Technologies for Vertical Flight, Ben Chiswick and Dr. Satyam Joshi detailed the engineering challenges, optimization strategies, and systems-level thinking required to transform automotive hydrogen fuel cells into practical propulsion systems for eVTOLs and future regional aircraft.
The webinar revealed that the question is no longer whether hydrogen fuel cells can power aircraft. Instead, the challenge has become determining how existing fuel cell technologies can be redesigned, light weighted, and optimized to meet the demanding requirements of aviation.
FEV Aerospace: Bringing Nearly 50 Years of Engineering Experience to Hydrogen Aviation
FEV Group has been driving innovation since 1978 and today operates as a global engineering and consulting organization with more than 5,600 employees, over 45 subsidiaries, and more than 250 test facilities worldwide.
While many aviation professionals may be newly familiar with FEV Aerospace, the company's hydrogen experience extends back more than 25 years. Throughout that time, FEV has worked on fuel cell systems for passenger vehicles, commercial trucks, rail systems, stationary power applications, motorsports, and aerospace programs.
Their hydrogen portfolio includes:
Toyota Mirai and Hyundai Nexo fuel cell benchmarking
Fuel cell electric rail systems
Fuel cell range extenders
Commercial vehicle fuel cell development
Fuel cell stack design and validation
Hydrogen-powered Dakar Rally race vehicles
Aviation fuel cell research projects
Hydrogen ecosystem development and infrastructure planning
This extensive background allows FEV to transfer lessons learned from automotive development into emerging aviation applications.
Why Hydrogen Continues to Stand Out for Aviation
One of the most important themes throughout the webinar was energy density.
Hydrogen presents a unique tradeoff compared to conventional aviation fuels and batteries.
While liquid hydrogen requires significantly more storage volume than jet fuel, it offers dramatically higher specific energy by weight. This means aircraft can potentially carry far less fuel mass while achieving long range.
Batteries face the opposite challenge. They can be packaged efficiently, but their energy density remains far below what is required for long-range flight.
As aircraft designers seek pathways toward zero-carbon aviation, hydrogen continues to stand out as one of the few technologies capable of supporting meaningful range without the weight penalties associated with batteries.
The challenge is not the hydrogen itself. The challenge is creating fuel cell systems that are light enough and powerful enough to compete with traditional aircraft propulsion systems.
The Power Density Problem
The central technical challenge discussed during the webinar was power density.
Aircraft propulsion systems demand extraordinary performance. Every kilogram matters.
FEV compared four propulsion categories:
Helicopter turboshaft engines
Aircraft piston engines
Automotive fuel cells
Future aviation fuel cells
Turboshaft engines remain the benchmark for power density, while piston engines offer a balance of power and efficiency. Automotive fuel cells, however, were never designed with aviation requirements in mind.
Although they are highly efficient, current automotive fuel cell systems are substantially heavier than aircraft propulsion systems when measured on a power-per-kilogram basis.
According to FEV's analysis, future aviation fuel cell systems will likely need to achieve approximately 0.8 to 1.0 kW/kg at the system level in order to compete with piston-engine aircraft.
Achieving this goal will require redesigning nearly every major component within the fuel cell system.
Understanding Where the Weight Comes From
To determine where improvements could be made, FEV conducted detailed teardown studies of existing automotive fuel cell systems.
One benchmark system produced approximately 100 kW of net power and weighed 357 kilograms when paired with its hydrogen storage system.
The results were revealing.
Hydrogen storage represented roughly 40 percent of the system weight, while the fuel cell system itself accounted for approximately 60 percent.
Within the fuel cell assembly, major contributors included:
Bipolar plates
Housing structures
End plates
Cooling systems
Air management components
These findings helped identify four primary areas for future optimization:
Hydrogen storage systems
Bipolar plate technology
Housing and structural design
Thermal management systems
Liquid Hydrogen Is Essential for Aviation
One of the clearest conclusions from the presentation was the importance of liquid hydrogen.
Most automotive fuel cell systems use compressed hydrogen storage. While effective for ground transportation, compressed hydrogen is less attractive for aviation due to its lower energy density.
Switching to liquid hydrogen can approximately double storage density while significantly reducing overall system mass.
The transition introduces new challenges, including cryogenic storage, insulation requirements, and boil-off management. However, the weight savings and performance improvements make liquid hydrogen one of the most important enabling technologies for hydrogen-powered flight.
Reimagining the Fuel Cell Stack
The fuel cell stack itself represents another major opportunity.
Current automotive stacks commonly utilize stainless steel or graphite-based bipolar plates.
FEV highlighted several emerging technologies that could dramatically improve aviation suitability:
Titanium bipolar plates
Thin titanium sheet designs
Ultra-thin stainless steel structures
Hydroformed metal plate manufacturing
Advanced graphite compound technologies
The company's research indicates that future aviation-optimized stacks may achieve gravimetric power densities between 7 and 9 kW/kg at the stack level.
Reaching these targets will require both advanced materials and innovative manufacturing processes.
Why Cooling Is One of Aviation's Hardest Problems
Perhaps the most eye-opening section of the webinar focused on thermal management.
Fuel cells reject heat very differently than conventional aircraft engines.
In a turboshaft engine, most waste heat exits through the exhaust stream.
In an internal combustion aircraft engine, a substantial portion of heat also leaves through exhaust gases.
Fuel cells are different.
Approximately half of the fuel's energy ultimately becomes heat that must be removed through liquid cooling systems.
This creates a difficult challenge for aircraft designers.
Larger cooling systems increase:
Weight
Aerodynamic drag
Complexity
Power consumption
For eVTOL aircraft, cooling fans alone can consume 10 to 20 percent of available output power.
As a result, thermal management often becomes one of the dominant design constraints in fuel cell aircraft.
High Altitude Creates New Challenges
Fuel cells must also contend with a problem that automobiles rarely face: altitude.
As aircraft climb, air pressure decreases significantly.
Most automotive fuel cells are designed to operate near sea level and begin experiencing limitations around 10,000 feet.
Future aviation systems may need to operate at significantly higher altitudes.
To achieve this, FEV identified several required technologies:
Multi-stage compressors
Higher boost pressures
Improved air management systems
Turbine energy recovery
Specialized flow field designs
These systems increase complexity but are essential for maintaining fuel cell performance at altitude.
Real Aerospace Programs Already Underway
The presentation highlighted several aerospace projects demonstrating FEV's growing aviation footprint.
Safran Power Units
FEV supported a fuel cell feasibility study examining:
Air management loops
Hydrogen management systems
Thermal management architectures
Electrical distribution systems
Aircraft operating modes
Altitude effects
The project evaluated fuel cell propulsion architectures across all major flight phases, including taxi, takeoff, climb, cruise, approach, and landing.
Aerospace Fuel Cell Stack Development
FEV is also supporting the development of dedicated aerospace fuel cell stacks designed specifically for aviation requirements.
The effort focuses on:
High power density
Lightweight structures
Aerospace mission profiles
Shock and vibration resistance
Safety requirements
Long operational lifetimes
These projects demonstrate that aviation-specific fuel cell development is already well underway.
Building a Hydrogen-Powered eVTOL
The technical centerpiece of the webinar was a comprehensive eVTOL optimization study.
FEV created a conceptual aircraft featuring:
3,000 kg maximum takeoff weight
Eight lift rotors
Two cruise propellers
400 kg payload target
204 nautical mile range target
Cruise speed of 168 knots
To evaluate propulsion architectures, the team combined Stanford University's SUAVE aircraft dynamics software with GT-SUITE propulsion system modeling.
This allowed them to simulate aircraft performance while simultaneously modeling:
Fuel cell operation
Battery behavior
Thermal systems
Electric motors
Power electronics
Hydrogen storage
The result was a highly detailed digital engineering environment capable of optimizing the entire aircraft.
Fuel Cell Dominant vs Battery Dominant Architectures
The study examined two competing propulsion concepts.
Battery-Dominant Configuration
This approach uses a large battery pack as the primary energy source while relying on the fuel cell as a range extender.
Fuel Cell-Dominant Configuration
This architecture uses the fuel cell as the primary energy source while batteries support transient loads such as takeoff, climb transitions, and landing.
The results were decisive.
The fuel-cell-dominant aircraft required approximately 1,062 kg of propulsion system mass.
The battery-dominant aircraft required approximately 1,409 kg.
That difference of nearly 350 kilograms represented a major advantage for the hydrogen-focused architecture.
For long-range advanced air mobility missions, the fuel-cell-dominant configuration consistently outperformed the battery-dominant approach.
Finding the Optimal Hydrogen Aircraft
Using GT-SUITE's genetic algorithm optimization tools, FEV identified a promising propulsion configuration.
The optimized aircraft included:
366 kW fuel cell system
22.5 kWh battery
31 kg usable liquid hydrogen capacity
453-volt fuel cell stack
The resulting aircraft achieved approximately:
410 kg payload
Greater than 200 nautical miles range
Acceptable mission performance across all flight phases
While preliminary, the results provide valuable insight into what future hydrogen-powered eVTOL designs may look like.
The Future of Hydrogen Aviation
The webinar demonstrated that many of the technologies required for hydrogen-powered flight already exist today.
The challenge is not inventing fuel cells from scratch. The challenge is adapting decades of automotive development to aviation's unique requirements.
Through lightweight structures, advanced cooling systems, liquid hydrogen storage, improved air management, and system-level optimization, fuel cells are steadily moving closer to becoming a practical aviation propulsion solution.
As the industry continues to pursue zero-carbon flight, presentations like this highlight how much progress is already occurring behind the scenes.
For hydrogen aviation, the future may arrive sooner than many people realize.
FAQ
1. Why are automotive fuel cells being used as a starting point for aviation?
Automotive fuel cells have benefited from decades of development, testing, manufacturing experience, and cost reductions. Aviation companies can build on that foundation instead of starting from scratch.
2. What is power density?
Power density measures how much power a system produces relative to its weight. Higher power density is critical for aircraft because every kilogram affects performance.
3. Why is liquid hydrogen preferred over compressed hydrogen for aircraft?
Liquid hydrogen stores much more energy in a smaller and lighter package, making it more practical for long-range aviation.
4. Why are fuel cells difficult to cool?
Unlike jet engines, fuel cells reject most of their waste heat through liquid cooling systems rather than exhaust gases.
5. What are bipolar plates?
Bipolar plates distribute hydrogen and air inside a fuel cell while also conducting electricity between individual cells.
6. What is an eVTOL?
An eVTOL is an electric Vertical Takeoff and Landing aircraft designed for advanced air mobility and urban transportation.
7. Why do batteries struggle with long-range aviation?
Batteries have much lower energy density than hydrogen, which means aircraft must carry significantly more weight to achieve the same range.
8. Why do fuel cells need compressors?
Fuel cells require oxygen from the atmosphere. Compressors help maintain airflow and pressure, especially at higher altitudes.
9. What is a fuel-cell-dominant aircraft?
It is an aircraft where the fuel cell provides most of the energy while batteries handle short bursts of high-power demand.
10. What was the biggest takeaway from the webinar?
Hydrogen aviation is no longer just a concept. Engineers are now solving specific design challenges that will allow existing fuel cell technology to become practical for flight.
HYSKY Society Mission
HYSKY Society is a 501(c)(3) nonprofit committed to decarbonizing aviation and aerospace with hydrogen. We welcome innovators from eVTOLs/advanced air mobility, fixed-wing aircraft, and spacecraft. Our mission is simple: if it defies gravity and uses hydrogen as fuel, it’s part of our vision for sustainable flight.
