Hydrogen-electric: a compelling case

Most likely, the tech that enables us to fly cleanly in the future has not been invented yet, so why do so many in the industry think the hydrogen-electric engine is the best pathway to future zero emissions?

Well, the typical hydrogen-electric engine can already harness 60 times more energy than lithium-ion batteries – and for a significantly lower cost too.

Universal Hydrogen, a Californian-based company founded in 2020, is one of several making serious headway in the sector – and it already has an order to convert 75 planes for US carrier Connect Airlines.

Europe also staged hydrogen-electric trials last year: H2FLY, a German company based in Stuttgart with funding from several ministries, oversaw four flights taking off in Maribor, Slovenia, of which the longest lasted for three hours.

The H2FLY aircraft uses liquid hydrogen to power a hydrogen-electric fuel cell propulsion system. Using hydrogen gas, the planes have a range of 750 km, but this doubles using cryogenically-stored liquid hydrogen, which enables lower tank weights and volume, thus increasing the range and useful payload.

The timeline is not groundbreaking though. For example, British-American developer ZeroAvia – which welcomed Satair onboard as an investor in September 2023 along with Alaska Airlines and some big hitting investment funds – has plans to start retrofitting existing planes with its hydrogen-electric powertrains in 2025.

The powertrains will exert 15 times as much power than a battery-powered engine and be two to three times more fuel-efficient.

Its first engine in 2025 will fly planes with 9-19 seats and a range of 300 nautical miles, followed by larger models in 2027 (40-80 seats), 2029 (100-200 seats) and 2032 (200 seats). But it is only by 2040 that it expects to retrofit a plane capable of intercontinental travel (200+ seats).

One airline to sign up is British green pioneer Ecojet, which in November 2023 confirmed its intention to buy 70 of ZeroAvia’s hydrogen-electric engines to power its planes. In 2027, it will become one of the first to take the ZA2000 engine, which will offer power in the range of 2.0-5.4 MW and fly 80-seaters.

Other airlines taking major strides in the sector include: Avolon, Delta Airlines, EasyJet, GOL, Icelandair, Japan Airlines, JetBlue, SAS, United Airlines, Vertical Aerospace, Virgin Atlantic, Viva Aerobus and Wideroe.

Growing MRO interest in the sector

ZeroAvia has been busy signing deals with MRO operators with a particular interest in hydrogen-electric engines.

For example, the Aerospace Engineering Center department at the MHI RJ Aviation Group has confirmed it will be providing MRO expertise to ZeroAvia – particularly in regard to engineering services, aircraft integration and certification support – and a number of OEMs have expressed interest in getting involved.

MRO operators cannot ignore this development. They will need to move with the times and start stocking spare parts for hydrogen-electric engines – as part of an overall strategy to get ready for a future in which clean fuel will power the world’s planes.

If they don’t, they run the risk that operators will shop elsewhere because as part of a lengthy transitional period they will have a mixed fleet of new gen hybrid aircraft and conventional aircraft solely powered by non-sustainable fuel, and they will favour USM suppliers that can cater to all their needs, instead of having to visit multiple suppliers.

US engineering services provider AeroTEC is one such operator. It takes pride in its ability to provide aftermarket support to one-off aircraft that other MRO providers might lack the capability or willingness to service. Its support includes aircraft integration, modifications, design, parts manufacturing, and safety and detail analysis.

It not only provides hydrogen-electric support (to the likes of MagniX/NASA, Surf Air Mobility and Universal Hydrogen) but also parts to electric operators (such as MagniX and Eviation) – so it’s clearly hedging its bets about what the future might bring.

Another MRO making moves is Lufthansa Technik, which in 2021 launched a project to design and test hydrogen tech processes.

It transformed a decommissioned A320 into what it describes as a “stationary laboratory”, where it is testing out internal cryo-tanks for liquid hydrogen, a fuel-cell system and a conditioning system. It is also considering the practicality of refuelling, repairs and potential incidents.

New future, new skills

AeroTEC harbours plans to also provide training – a necessity in this new age of MRO for not only the next generation of planes, but also vertiports and electric vertical-takeoff-and-landing (eVTOL) aircraft, such as air taxis and drones.

MRO workers will need to seriously upgrade their skill sets across a wide range of new tech: from AI-powered IT to high-voltage electronics.

Safety is also an incentive as liquid hydrogen cyro-tanks require cooling to -250C while the high-voltage electronics require 800-1,000 volts of electricity – more than enough to kill a worker who doesn’t follow procedure.

However, experts believe the switch to hydrogen solutions could simplify engine maintenance, not complicate it. They predict reduced wear and tear – primarily due to a significant lowering of engine part temperatures. Reduced combustion and fewer rotating components play a part in this.

But the technology isn’t in place at the moment for larger plans, the experts concur – particularly in regards to cooling hydrogen for use in a combustion engine. A breakthrough is needed.

A Russian experiment in the 1980s, the Tupolev Tu-155, encountered the same problem. The result was a plane filled with tubes and refrigeration units with no room for seats, let alone passengers.

This missing link in the future development of hydrogen-electric tech could still leave the door open for green fuels that power conventional engines.

Rise of the vertiports: a look at recent developments concerning the futuristic air hubs

Digital services

Quick Links

Quick Links

Legal Links

How hydrogen-focused MROs are preparing aviation for the future