The transition to hydrogen-fuelled flights, initially on regional air routes, has received a double boost, with major milestones announced by two leading powertrain developers, ZeroAvia and Universal Hydrogen. Both companies are developing hydrogen propulsion systems to replace fossil-fuelled engines in existing commuter planes and are progressing flight test programmes. ZeroAvia has just secured additional funding  from 10 investors, jointly-led by Airbus, Barclays Sustainable Impact Capital and Saudi Arabia’s NEOM, to progress certification of its entry-level ZA600 powertrain, designed to retrofit 9-20 seat commuter planes. Airbus and ZeroAvia will also collaborate on key technical issues to help achieve certification of hydrogen propulsion. In the US, the Federal Aviation Administration (FAA) has accepted an application by Universal Hydrogen for a Supplemental Type Certificate (STC) to convert ATR72 regional turboprops to hydrogen propulsion, and has provided essential documentation for the certification process.

ZeroAvia is developing a family of hydrogen-electric engines that use hydrogen in fuel cells to produce electricity, which then powers electric motors to spin the aircraft’s propellors. Airbus, Barclays and Saudi Arabia’s NEOM were joined in the latest investment round by Breakthrough Energy Ventures, Horizons Ventures, Alaska Airlines, Ecosystem Integrity Fund, Summa Equity, AP Ventures and Amazon Climate Pledge Fund.

First-stage flight testing of the ZA600 protype was completed recently and ZeroAvia is now undertaking final design work required to achieve certification, targeting entry into service in 2025. As well as supporting this programme, supported by two converted Dornier 228 testbed planes, the additional funding will help progress development of the company’s next engine, the ZA2000, a 2-5.4MW powerplant designed for use on larger aircraft. ZeroAvia is converting a 76-seat Dash 8-400 turboprop, formerly operated by Alaska Airlines, for use as a demonstrator aircraft, and aiming to flight test this engine concept next year. 

Airbus, a leading proponent of hydrogen-powered aircraft, has additionally agreed to collaborate with ZeroAvia on certification approaches for the propulsion systems, focusing on key technical areas including liquid hydrogen fuel storage, ground and flight testing of fuel propulsion systems, and development of refuelling infrastructure and operations for hydrogen-powered planes. Both companies are already working with partners including major and regional airports on operational challenges including transportation, storage and delivery of hydrogen fuel.

Through its ZEROe aircraft programme, in which fuel cell systems are a key element, Airbus recently conducted ground tests with a hydrogen engine concept at 1.2MW power. By the late 2020s, it will use A380 research aircraft to commence flight testing of hydrogen propulsion concepts as part of its own ambition to introduce a new zero-emission airliner into commercial service by 2035. 

ZeroAvia’s founder and CEO, Val Miftakhov, welcomed the Airbus investment as a strong endorsement of his own company’s progress in hydrogen propulsion. “Anybody following the development of hydrogen aviation, and its potential to transform the industry, will see this investment as a positive step,” he said. “Airbus has led the way with its zero-emission vision and a commitment to extensive research and development programmes. For ZeroAvia to now have investors such as Airbus coming on board is the strongest possible validation of the prospects for hydrogen-electric propulsion technology.” 

Glen Llewellyn, Airbus VP, ZEROe Aircraft, said ZeroAvia’s success in flight-testing fuel cell propulsion, and hydrogen storage and distribution systems on its Dornier 228 research aircraft, had put the company in a strong position to advance its technologies. “In addition,” he said, “ZeroAvia is supporting the development of a wider hydrogen ecosystem for aviation – technologies, decarbonised hydrogen supply and certification of hydrogen propulsion systems – which all complement well with our own ambition to bring ZEROe hydrogen-powered aircraft to service by 2035.”   

Repeat investor Barclays said green hydrogen was a leading decarbonisation pathway for hard-to-abate sectors including aviation. “Our Sustainable Impact Capital portfolio is one of many ways in which Barclays is supporting green-tech companies to innovate and scale, recognising that doing so at speed is crucial for a timely transition to net zero,” explained Andy Challis, the company’s Co-Head of Principal Investments. “ZeroAvia has shown that with ambition, technological innovation and the right support from both the public and private sector, it is possible to scale and implement such hydrogen technologies at pace, as evidenced by the ZA600 moving ever-closer to commercial flight.”

Saudi Arabia’s NEOM, the other lead investor in ZeroAvia’s latest funding round, said it was committed to maximising the use of renewably-produced energy. “Developing a green hydrogen future is central to NEOM’s Mission,” said Majid Mufti, Managing Director of the NEOM Investment Fund. “Participating in this venture with ZeroAvia was a natural choice for us.” 

Over in California, Universal Hydrogen has developed a modular system in which capsules of hydrogen are transported to airports, then loaded onto the aircraft they will power, eliminating the need for dedicated airport fuelling infrastructure.

The start-up commenced flight tests earlier this year of its 40-seat Dash 8-300 testbed ‘Lightning McClean’, the largest fuel-cell powered aircraft to fly. It expects its test and certification programme to take two years, and is targeting 2025 for entry into service of larger ATR72 turboprop aircraft, powered by its containerised hydrogen fuel.

The company has now secured key documentation from the FAA to establish certification criteria, as part of its plan to convert conventionally-powered ATR72s to use portable liquid hydrogen modules to power a fuel cell-electric propulsion system.

The FAA has accepted Universal’s application for a Supplementary Type Certificate (STC) to convert ATR aircraft, and has granted a G-1 Issue Paper, a key step in developing certification criteria that includes development of airworthiness and environmental standards which the converted ATR would need to meet. As well as the new propulsion system, the Universal Hydrogen conversion also requires structural changes to aircraft to load and accommodate the hydrogen fuel canisters.

Like ZeroAvia, Universal Hydrogen is well backed by highly-credentialled investors including Airbus Ventures, GE Aviation, JetBlue Ventures, American Airlines, Toyota Ventures and a mix of green energy and sustainable finance partners. Among its customers is US start-up carrier Connect Airlines, which has announced orders for 75 ATR72 conversion kits and options for 25 more.

“I believe we have an industry first here,” said Mark Cousin, Universal’s President and CTO. “We appreciate our responsibility to ensure the airworthiness certification criteria that are established set a positive precedent for the rest of the nascent hydrogen aviation industry.”

Universal Hydrogen advisor Carl Burleson, a former Acting Deputy Administrator of the FAA, added: “For something as novel as hydrogen-powered airplanes, establishing the certification basis is a critically important milestone in the certification process. This is the culmination of nearly two years of effort between Universal Hydrogen and the FAA on this trailblazing project, which represents a key part of the solution set to help address the aviation industry’s commitment to a zero-carbon future.”

Image: In August, new Canary Islands operator Surcar Airlines selected ZeroAvia’s ZA600 hydrogen-electric engines to retrofit a Twin Otter seaplane variant

Editor’s note: Both Airbus and ZeroAvia will be talking about the latest developments in hydrogen-powered aircraft technology at the Aviation Carbon 2023 conference, co-organised by GreenAir and taking place in London on November 6/7.

Tony Harrington

Correspondent

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