ZeroAvia, a company developing hydrogen-powered aircraft, shared its views on the present and future of hydrogen aviation
When ZeroAvia first formed, our enthusiasm for fuel cells in hydrogen was too often met with a close-minded cynicism. There was a common (although flawed) assumption among some industry watchers that battery energy density would improve five-fold in less than a decade and that Sustainable Aviation Fuel would rapidly scale up production and thus adoption by airlines.
A number of factors changed these preconceptions in the early part of this decade. First, Airbus launched its ZEROe program, then the Aerospace Technology Institute’s Fly Zero project published a definitive tome of reports which pinpointed liquid hydrogen as the ultimate fuel of the future for aviation (and with huge potential near-term application), then, most importantly, the aircraft started to fly! First, ZeroAvia’s 2020 six seat hydrogen-electric demonstrator, then our testbed 19-seat Dornier 228, and then also erstwhile competitor Universal Hydrogen’s Dash 8 Q300 flights. Rolls-Royce and easyJet then showed how comfortable an aircraft jet engine could be burning hydrogen with a ground test, Joby/H2Fly completed a landmark 523 nautical mile flight on fuel cell power using liquid hydrogen.
The market impact of these factors was big, and over the course of this time we saw major airlines go from pre-orders to definitive purchase orders, and we welcomed investment from Airbus, IAG, American, United, Alaska and other industry heavyweights.
A New Impetus
While timelines on some large commercial aircraft projects have slipped back, there is a bank of demand for engines, and certification projects are underway. It could be argued that it is a matter of time before the next great transition in commercial aircraft propulsion really takes hold.
Separately, hydrogen is picking up new impetus in other segments of aviation thanks to a unique set of drivers: new approaches to regulation, a thirst for greater endurance of novel electrical aircraft, such as electric Vertical Take-off and Landing (eVTOL) and Unmanned Aerial Vehicles (UAV), and corresponding space and weight efficiency advances in low-to-mid power modular hydrogen fuel cell systems.
While large commercial airframes await technology advancement of high- temperature, next generation hydrogen fuel cells, at the smaller end, there are huge potential applications for streamlined, aerospace grade low-temperature proton exchange membrane (LTPEM) fuel cell systems.
FAA Mosaic and Fuel Cell Adoption
In August of this year, the Federal Aviaton Administration launched the Modernization of Special Airworthiness Certification (MOSAIC) rule, with profound implications for the applicability of fuel cell propulsion in the general aviation category.
The changes include removing weight limit as a key qualification and allowing up to four seats, thus broadening the design envelope for aircraft that can obtain regulatory approval without a type certificate and a production certificate.
Qualifying aircraft are no longer limited to single piston engines, opening up the opportunity to certify these with new electric and hydrogen-electric powertrains. As with other aircraft segments, electric aircraft would deliver the best efficiency and maintenance costs, and hydrogen-electric would provide the best range of all electric options.
EIPP and Hydrogen-Electric VTOL
As the U.S. gets ready to kick demonstration of eVTOL platforms up a notch following the launch of the eVTOL and AAM Integration Pilot Program (EIPP), attention is turning to how these first demonstrated routes can be expanded to more use cases.
Replacing battery power systems with hydrogen fuel cells can significantly extend range,reduce maintenance costs caused by battery cycling, and improve operations thanks to quicker turnaround time (hydrogen refueling vs lengthy battery recharge times).
As regional aviation looks to the adoption of hydrogen for fixed-wing long-distance flight, many airports already have active programs examining hydrogen for both air and ground operations. EVTOL can be a further demand case for these growing hydrogen hubs at airport, with the sector benefiting from existing plans to establish infrastructure.
The key ingredient for the light-sport and eVTOL categories is modular, flexible fuel cell systems with power generation somewhere between a typical automotive application and a larger fixed-wing aircraft. As aerospace innovators push the boundaries of clean flight, one challenge persists: most current hydrogen fuel cell solutions aren’t designed with aviation’s unique constraints in mind. Flight duration, integration complexity, and weight limitations often hinder adoption.
The SuperStack Flex
ZeroAvia’s SuperStack Flex Fuel Cell System
ZeroAvia’s SuperStack Flex is a unique innovation in LTPEM hydrogen fuel cell platforms, engineered for flexibility, scalability, and ease of integration. Unlike traditional systems, the SuperStack Flex embraces a modular architecture, allowing it to adapt to a wide range of aircraft types, mission profiles, and testing environments.
SuperStack Flex offers scalable power output, is compact and lightweight to meet aviation’s strict weight and space constraints, and allows flexible integration, making it compatible with both conventional and unconventional aircraft structures.
ZeroAvia has made great strides on a system for 10-20 seat planes, but maintaining high specific power and aerospace-relevant design while reducing the power output to support smaller aircraft presented significant engineering challenges.
Additive Manufacturing at the core of our design
A key enabler in the system’s design and development is the use of Selective Laser Sintering (SLS) additive manufacturing. This allows for:
- Faster re-engineering and prototyping
- Integration of complex internal fluidic paths
- Reduction in part count and system complexity
By leveraging additive manufacturing, we can quickly respond to new integration challenges and fine tune system components for optimal performance in flight-specific environments.
SLS Additive Manufacturing
Enabling a Whole New Way to Fly
Advanced air mobility is coming. EVTOL designs are marching towards certification. General Aviation is empowered to innovate by a less restrictive regulatory environment. Together, these things mean a whole new way to fly is coming, and ZeroAvia LTPEM hydrogen fuel cells offer a practical pathway to deliver efficiency, endurance and low costs. Read more about our SuperStack Flex to see just how.
Image of ZeroAvia (ZeroAvia’s SuperStack Flex Fuel Cell System)
