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ZeroAvia secures £12.3M UK Government grant to bring 19-seat hydrogen-electric aviation powertrain to market; HyFlyer II

ZeroAvia, an innovator in decarbonizing commercial aviation, secured £12.3 million (US$16.6 million) in UK Government funding through the ATI Program to deliver a breakthrough 19-seat hydrogen-electric powered aircraft that is market-ready by 2023: the HyFlyer II project.

To accomplish this, ZeroAvia will collaborate with two partners, the European Marine Energy Centre and Aeristech. The HyFlyer II project will conclude with another world’s first hydrogen-electric flight by ZeroAvia in a 19-seat aircraft, with a 350-mile flight, in early 2023.

The Government support for ZeroAvia’s 19-seat program comes as the company also announces £16 million ($21.6 million) in Series A venture funding.

The grant award follows ZeroAvia’s world first flight of a commercial-grade hydrogen-electric aircraft at Cranfield in September (earlier post), utilizing a smaller version of ZeroAvia’s hydrogen fuel cell powertrain in a 6-seat Piper Malibu M350. This earlier flight was a milestone for the first HyFlyer project, which was also supported with a grant from the ATI Program.

HyFlyer II will build on this success by bringing to market the first hydrogen-electric powertrain suitable for aircraft of up to 19-seats by 2023. Typically, up to 19-seat aircraft such as the Cessna 208 Caravan and the Viking Air DHC-6 Twin Otter are used in regional aviation and cargo transport worldwide. ZeroAvia’s 600kW hydrogen-electric powertrain is platform-agnostic and will begin to make zero carbon flight over meaningful distances a reality for passengers.

The announcements of the HyFlyer II program and Series A investment come just days after British Airways announced a partnership with ZeroAvia to speed up the switch to hydrogen-powered aircraft as part of IAG’s Hangar 51 tech accelerator program. (Earlier post.)

Hydrogen fuel-cell technology has been acknowledged by aerospace leaders and majors such as the European Regions Airlines Association and Airbus as the most practical way of rapidly removing carbon emissions from aviation.

For the HyFlyer II project, ZeroAvia is working again with the European Marine Energy Centre (EMEC) to deliver the green hydrogen fueling systems required to power the aircraft for flight tests, including through mobile fueling platforms suited to airport environments.

HyFlyer II is an important next step for ZeroAvia’s sequential R&D pathway to realising the transformational possibilities of moving from fossil fuels to zero-emission hydrogen as the primary energy source for commercial aviation. Eventually, and without any new fundamental science required, hydrogen-powered aircraft will match the flight distances and payload of the current fossil fuel aircraft.

Recently, ZeroAvia was also invited by Prime Minister Boris Johnson to join the UK’s Jet Zero Council and help lead the UK towards the ambitious goal of achieving the first ever zero emission long haul passenger flight.

ZeroAvia predicts its hydrogen-electric powertrain will have lower operating costs than its jet-fueled competition due to lower fuel and maintenance costs, in addition to reducing the air pollution today’s aircraft emit. ​

As the company commercializes its technology starting in 2023, ZeroAvia plans to offer hydrogen fuel production and supply for its powertrains, and other commercial customers, substantially improving fuel availability and reducing pricing risks for the entire market.



Claiming 300 to 500 mile range. Could do that with batteries a lot cheaper and simpler. Boris might have been sold a pup here.



Learn something about batteries if you wish to advocate them.
The weight for that range and payload would be prohibative.

The engineers who specified fuel cells and hydrogen for this application to achieve ZEV flight are not morons who missed the obvious.


I agree the engineers are not morons.
They are doing what they are being paid to do.

I am sure they can probably build a hydrogen fueled plane. The question is why.
To provide 700bar hydrogen at the small airports this plane is aimed for is problematic.
Hydrogen will always be expensive(unless made from fossil fuels).
With the incremental increase in energy density and the drop in price of batteries hydrogen may have a niche position but cannot compete in the market place without financial help or the use of fossil fuels.
As sd relates in a lower comment there is a 9 seater with a range of 420 miles running on batteries and they planning to fly the hydrogen Malibu 300 miles.


I'm not absolutely sure but I think it was around 2004 that Mike Millikin founded Green Car Congress. His main interest centered on green personal transportation and transportation in general. The title of this Blog "Green CAR Congress" reflects - in my opinion - his primary intention.
I, personally, am somewhat frustrated at times to see what Brain Stupefying contents (BS) are posted now and then that have absolutely nothing to do with the intended purposes.
The current practices of producing H2 have nothing in common with "green methods". Splitting NG into H2 and emitting remaining pollutants into the environment is well known as green-washing. What is being preached of what could be done in 20 years time or in another 20 years beyond that is not what is currently taking place. I know that I repeat myself needlessly when I state that renewable energy is to precious to be wasted in a H2-Infrastructure but there are alternatives.
e. g.
Wasting precious renewable energies for H2 production is not recommendable. Either put bacteria to work or forget it.

Roger Pham

Aircraft can use Liquid H2 (LH2) as fuel, which weighs 1/3 that of petroleum fuel for a given amount of BTU. Then, for 19-seat passenger aircraft, the FC is 3 x more efficient than an equivalent 400-600-kW gas turbine. So, already, we may end up with fuel weight about 1/9 that of the jetfuel weight just on the basis of 3x gains in thermal efficiency and 3x gain in gravimetric energy density.

Ah, but there's more: Fuel weight is generally 1/2-2/3 of useful load of the aircraft, with the remaining for payload, and fuel weight can be as much as 1/3 to 1/2 of the gross takeoff weight.. Thus, the entire aircraft can be downsized to have smaller wings, smaller tails, smaller propulsion system, smaller landing gears which will save even more weight and would end up consuming 75% of the energy per mile per kg of payload. So, multiplying 3 folds thermal efficiency gain of the FC with 1.33 folds gain in energy efficiency per unit of payload due to weight and drag reduction = 4 folds gain in fuel efficiency when converted to LH2-FC propulsion system. So, the LH2 fuel weighs practically nothing when so little of it is being used, AND with 3 folds higher in energy content per unit of mass: 4 x 3 = 12 folds lower fuel mass per kg of payload. Let's say that the Cessna Caravan carries 2,200 lbs of jetfuel, then an equivalent-payload LH2-FC plane would carry only 183 lbs of fuel, or just the weight of ONE passenger.

This extremely low fuel mass has major implication in the crash safety of the aircraft, with high percentages of deaths of current small plane crashes from post-crash fire from otherwise survivable crash. Jetfuel is placed in the wings, which is very likely to break up after even a low-impact crash, causing fuel rupture which will cause lethal fires. The LH2 fuel tank could be placed in well-protected insulation structures (thick polyurethane foam) in the rear of the fuselage whereupon the fuel tank holding very light fuel will very likely stay intact after a survivable crash. Rear section of aircraft always stay intact after impact-survivable crashes.

So, LH2 is very advantageous for aviation, and we are bound to achieve as much as 12 folds gain in fuel efficiency in comparison to petroleum fuel in small aircraft, and much gain in safety at the same time from post-crash fires and from increase reliability of the propulsion system, with dual e-motors and dual FC system powering a single propeller.

Roger Pham

Correction to my posting above: "...and we are bound to achieve as much as 4 folds gain in fuel efficiency in comparison to petroleum fuel in small aircraft, ..."
instead of "12 folds gain in fuel efficiency" as stated.

Roger Pham

Another way to look at LH2 fuel consumption per lb of payload is to realize that for the Cessna Caravan with 8,000 lbs gross weight, 4,700 lbs empty weight, and 3,300 lbs usefull load, with maximum fuel weight of 2,200 lbs, it has only 1,100 lbs of payload.
Even if the aircraft is not downsized, then when subtracting the 244-lb of LH2 (2,200 lbs divided by 9 folds less fuel mass) from the 3,300 lbs of useful load, we would have 3,056 lbs of PAYLOAD available for the full range as with 2,200 lbs of jetfuel earlier, but now, with the huge PAYLOAD of 3,056 lbs, we almost TRIPLE the payload capacity for the LH2 in the non-downsized version of the Cessna Caravan as the result of using LH2-FC propulsion system.

So, we have almost tripled the payload capacity, while using only 1/3 of the fuel caloric value due to 3 folds gain in thermal efficiency of the FC would means 9 folds gain in fuel efficiency of LH2 per lb of payload.


I wish more posters here had the wisdom of bman.


Roger Pharm
First luv your work Roger.
But this time youve strayed into fanciful territory.
Claiming that FCs are 3X as efficient as turboprops is a bit of a stretch. We know that PEMs are ~50% efficient at best and that energy must then be translated to motive power via an emotor , a loss of another 10% so 45%.
The present F1 engines are claiming >50%. Toyotas 4 cylinder engine claims to have efficiency >40%. Big diesels are also getting ~45%.
But I do agree that PEMFCs would be more efficient than turboprops.
The real problem is liquid hydrogen. I get flashbacks of the Challenger disaster.
Handling the stuff at -250 to-260 degrees C, in a commercial setting, nup.
If you really must have FCs ,then go for SOFCs with a liquid fuel.
Not really green but you could call it biofuel.


Good to see your comments, you are right about the extra payload.
FCs are more efficient than turbo props and the hydrogen cost can be reduced by selling the oxygen using low cost wind and solar.

Roger Pham

Thanks for your comment and feedback.
1.. Regarding the efficiency of FC, new generation of higher-temp FC is now able to reach 70% efficiency with temperature of 150 dgr C, thus allowing significant reduction in the size of the radiator and making higher power possible in aviation. Also, power density of as much as 6 kW per liter and 4 kW per kg is now possible, while motors having 5-6 kW per kg is now available, making the weight of the entire propulsion competitive with turboprop. Of course, peak power is only needed for a few minutes during takeoff at full gross weight, and can be throttled back to 75% during climb, and way back during cruise at altitude.

2.. Regarding the Challenger disaster, from Wikipedia: "The disintegration of the vehicle began after a joint in its right solid rocket booster (SRB) failed at liftoff. The failure was caused by the failure of O-ring seals used in the joint that were not designed to handle the unusually cold conditions that existed at this launch. The seals' failure caused a breach in the SRB joint, allowing pressurized burning gas from within the solid rocket motor to reach the outside and impinge upon the adjacent SRB aft field joint attachment hardware and external fuel tank. This led to the separation of the right-hand SRB's aft field joint attachment and the structural failure of the external tank. Aerodynamic forces broke up the orbiter." There is no mention of LH2 at all as having anything to do with this disaster. Just the solid boosters and aerodynamic forces the broke up the vehicle.

3.. With LH2, the very light nature of it and the thick polyurethane foam insulation required means that the fuel tank is very strong and big for the inertial force of the fuel and should hold up very well, far better than heavy petroleum fuel in flimsy aluminum skin fuel tanks inside the wings. Would a fuel tank leak cause fire? Since the fuel is so cold, no fire can happen adjacent to the aircraft, but much further behind and above the aircraft, as the LH2 has the chance to vaporize and gain heat and floats upward and mixed with air. A lot of steps must happen before the cryogenic LH2 can catch fire, well above and behind the aircraft.

Roger Pham

The thermal efficiency of a small turboprop engine in the 600 hp range in the Cessna Caravan is around 20-22%. The bigger turboprop engine in the 1,200 hp range as in the PC12 has efficiency around 25%. The efficiency of the Kuznetsov NK-12 turboprop engine, 12,000 hp, in the Russian Bear bomber is around 33%. Large jetliner turbofans have the core turbine engine with efficiency around 45-50%, somewhat comparable to earlier generation of FC.


Roger Pharm
Thank you for your well crafted comment.
The 70% efficiency for 150degreeC FC is stated as a target.
Ive seen cell startups "targeting " 400wh/kg for years now.
I truly hope both come true but I reckon the batteries might get there first.

Account Deleted

Please forget about Liquid H2 for General Aviation.
This technology has been explored for years and the infrastructure and cost issues are very large. Soviet Russia developed a Liquid H2 commercial aircraft in the 1960's (the Tupolev TU-155) even this was too expensive. NASA solved the technical issues of liquid H2 decades ago (read: https://www.nasa.gov/topics/technology/hydrogen/hydrogen_fuel_of_choice.html. However, even for Space travel, SpaceX and BlueOrigin are using LNG,i.e. LH2 is still too expensive.
This is my take on all of this.
There is still hope for FC powered aircraft (particularly VTOL). The best bet is solid state H2 storage which has better volumetric and gravimetric energy density than even LH2. Some are looking at Kubas Maganese Hydride, but this is still in the early stages of development. My bet and that includes Sandy Munro is the "nano solid state tech" from Australia being developed by University of NSW professor Kondo-Francois Aguey-Zinsou. You can read about it here: https://www.smh.com.au/environment/climate-change/alchemy-of-energy-breakthrough-offers-mass-hydrogen-storage-options-20200702-p558dj.html.

Professor Aguey-Zinsou said the H2 alloy contained titanium and "other common materials", maybe it is based on this research: "Stabilization of Nanosized Borohydrides for Hydrogen Storage: Suppressing the Melting with TiCl3Doping"
(reference: https://pubs.acs.org/doi/abs/10.1021/acsaem.7b00082).
Maybe this will develop soon.

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