ZeroAvia claims it has achieved record-breaking performance in testing its 20kW high temperature proton exchange membrane (HTPEM) stack power module, early testing of which demonstrated a record 2.5 kW/kg specific power at the cell level at the company’s UK R&D location, paving the way for more than 3 kW/kg system level densities in the next 24 months.

Developing fuel cell technology for aviation is critical to enable true zero-emission commercial flight, and for energy intensive applications like large fixed wing aircraft and rotorcraft, it is necessary to increase the temperature and pressure within fuel cell stacks in order to have a commercially viable product.

Increased temperature and pressure allows for air cooling, reduces cooling drag, simplifies the system, and ultimately enables much more demanding applications.

ZeroAvia’s team has made unprecedented deep tech breakthroughs by delivering a pressurized HTPEM system, innovative conductive coatings enabling the use of aluminum bipolar plates in highly aggressive HTPEM environments, and a novel approach to advanced membrane electrode assembly.

HTPEM will support ZeroAvia’s ZA2000 powertrain for 40-80 seat aircraft, as well as a range of rotorcraft and eVTOL applications. These fuel cells may also enable electric propulsion systems for 100+ seat single-aisle turbofan aircraft such as the Boeing 737 and Airbus A320.

The components used in the ZeroAvia system have already been validated through third-party independent testing at several independent labs, including a leading U.S. Department of Energy national lab.

ZeroAvia’s recent breakthrough first flight of a 19-seat aircraft employed low temperature PEM fuel cell systems for the sub-megawatt scale of smaller aircraft, but the lower stack core temperatures make it harder to remove heat from the larger systems.

HTPEM technology eliminates a number of components from the fuel cell system and reduces cooling drag, thereby enabling commercial payload and range with greater durability.

ZeroAvia CEO Val Miftakhov said: “The companies and geographies that seize the lead in high fuel cell temperatures and pressures will lead the industry, similar to the story of turbine engines, where increasing temperature and pressure drove higher performance.

“Hydrogen fuel cell propulsion is the most environmental and economical alternative to existing engines, and HTPEM is the most promising route to delivering these benefits into large aircraft categories.”

Hydrogen combustion engines remove carbon emissions from flight, but face a steep environmental penalty in maintaining or increasing non-CO2 emissions, which are thought to have twice the climate impact of carbon emissions alone, according to a report from EASA.

Additionally, a non-combustion, hydrogen-electric approach eliminates extreme material stresses inherent in modern combustion engines, which dramatically reduces maintenance costs.

ZeroAvia’s development of the HTPEM systems is in part supported by the HyFlyer II project, backed by the UK Government via the Aerospace Technology Institute (ATI).