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Universal Hydrogen successfully completes first flight of hydrogen fuel cell powered regional airliner

Universal Hydrogen has flown a 40-passenger regional airliner using hydrogen fuel cell propulsion. The airplane, nicknamed Lightning McClean, took off at 8:41am PST from Grant County International Airport (KMWH) and flew for 15 minutes, reaching an altitude of 3,500 MSL. The flight, conducted under an FAA Special Airworthiness Certificate, was the first in a two-year flight test campaign expected to culminate in 2025 with entry into passenger service of ATR 72 regional aircraft converted to run on hydrogen.


In this first test flight, one of the airplane’s turbine engines was replaced with Universal Hydrogen’s fuel cell-electric, megawatt-class powertrain. The other remained a conventional engine for safety of flight. The flight was piloted by Alex Kroll, an experienced former US Air Force test pilot and the company’s chief test pilot.

During the second circuit over the airport, we were comfortable with the performance of the hydrogen powertrain, so we were able to throttle back the fossil fuel turbine engine to demonstrate cruise principally on hydrogen power. The airplane handled beautifully, and the noise and vibrations from the fuel cell powertrain are significantly lower than from the conventional turbine engine.

—Alex Kroll

Representatives from Connect Airlines and Amelia, the US and European launch customers for the hydrogen airplanes, respectively, were on hand to witness the historic flight. The company has a rapidly growing order book, today totaling 247 aircraft conversions from 16 customers worldwide, totaling more than $1 billion in conversions backlog and more ethan $2 billion in fuel services over the first ten years of operation.

Connect, which will begin regional turboprop service this spring, has placed a first-position US order with Universal Hydrogen to convert 75 ATR 72-600 regional airplanes to hydrogen powertrains with purchase rights for 25 additional aircraft conversions. Deliveries will start in 2025.

The company’s powertrain is built around Plug Power’s ProGen family of fuel cells specially modified for aviation use. The powertrain does not use a battery—the fuel cells drive the electric motor directly—reducing weight and cost significantly.

The motor, a modified magni650 electric propulsion unit, and power electronics were supplied by Everett-based magniX. Seattle-based AeroTEC assisted with engineering efforts, including design of the modified nacelle structure, aircraft systems design and integration, as well as aircraft modifications and installation of the Universal Hydrogen powertrain onto the flight test aircraft, accomplished in less than 12 months.

The test flight comes on the back of successful demonstrations in December 2022 of Universal Hydrogen’s modular hydrogen logistics system conducted at the company’s engineering center in Toulouse, France.

Our business model resolves the chicken-and-egg problem between hydrogen airplanes and hydrogen infrastructure by developing both in parallel and with a uniquely low-cost approach. The airplanes are converted to hydrogen using an aftermarket retrofit conversion kit, tackling the existing fleet rather than developing a brand new airplane. And hydrogen fueling uses modular capsules compatible with existing freight networks and airport cargo handling equipment, making every airport in the world hydrogen-ready.

—Paul Eremenko, co-founder and CEO of Universal Hydrogen

The company, backed by GE Aviation, Airbus Ventures, Toyota Ventures, JetBlue Ventures, and American Airlines, as well as several of the world’s largest green hydrogen producers and top-tier financial investors, plans to springboard from regional airplanes to larger ones and to hydrogen fuel deliveries for other mobility applications using its modular logistics network.



Here is an article on TechCrunch which does a pretty good job of outlining some of the issues which have to be overcome to get this tech flying routinely:

Some of the points made are a bit on the daft side in my view, with comments like until both engines are running on hydrogen, it is 'just a show'
Doh! Its an early test flight, with safety paramount.

But substantial points include:

' Part of the problem with today’s fuel cells is that they can be tricky to cool. Jet engines run much hotter, but expel most of that heat through their exhausts. Because fuel cells use an electrochemical reaction rather than simply burning hydrogen, the waste heat has to be removed through a system of heat exchangers and vents.'

It should be noted that Universal's system does not require power boosting with batteries.

And :

' Some experts are skeptical that hydrogen will ever make a meaningful dent in aviation’s emissions. Bernard van Dijk, an aviation scientist at the Hydrogen Science Coalition, appreciates the simplicity of Universal Hydrogen’s modules, but notes that even NASA has trouble controlling hydrogen leaks with its rockets. “You still have to connect the canisters to the aircraft. How is that all going to be safe? Because if it leaks and somebody lights a match, that is a recipe for disaster,” he says. “I think they’re also underestimating the whole certification process for a new hydrogen powertrain.”'

Along with Universal Hydrogen, I don't see the last point about where the green hydrogen is to come from as very substantial.

There are too many options out there.

Of course, the big attraction is that Universal Hydrogen's proposal to retrofit existing planes not only reduces costs but enables speedy GHG reduction.

Reduction of seating through installing hydrogen tanks is at least partly offset by the likely reduction in fuel costs against jet fuel, without counting the benefits of avoiding fried planet.

Safely handling the hydrogen sounds like the biggie to me.

I am looking forward to reading more expert opinion on this, which is almost anyone who isn't me! ;-)

Gunder Karlsson

Did the airplane use compressed hydrogen or liquified hydrogen? Liquid hydrogen is much more costly than the compressed.


From my link above:

' Today’s 15-minute flight used about 16kg of gaseous hydrogen — half the amount stored in two motorbike-sized tanks within the passenger compartment. Universal Hydrogen plans to convert its test aircraft to run on liquid hydrogen later this year.'

Aircraft are to use liquid, not gasesous hydrogen.
The biggest problems are keeping it cool oboard, not the cost.


I'm starting to realise why Gryf is somewhat less than enamoured with the idea of pumping liquid hydrogen at -253C around an aircraft, but am comforted by a couple of thoughts:

That it only has to happen up to wherever the liquid is turned into a gas, which presumably would be as close to the tank as possible, so perhaps the bigger issue is the modules containing the liquid hydrogen, which Universal Hydrogen proposed to install like a Nespresso capsule, perhaps with the aid of George Clooney.

That this is the sort of thing which can safely be left to mere technologists, whilst great spirits concentrate on first principles! ;-)

And if they do get stuck, there is always SAF to fall back on......


I absolutely believe that, in a technological sense, this will work. The bigger question is whether it will be an economical success. What I really doubt is that they will be carrying passengers by the end of 2025. I can not imagine meeting all of the regulations for carrying passengers in next 33 months when they just made a first flight with one engine running on small tanks of compressed hydrogen.

Personally, I believe that future regional aircraft will be battery powered but not by 2025. It will require higher energy density batteries and a redesigned airframe. Lyten has supposedly made lithium sulfur batteries with about 900 Whr/kg and 10 to 20 minute recharge time and has a time-line of 2025 for commercial production. These would work for regional aircraft but probably not before the 2030 time frame. The reason that I believe batteries will be used is because of the economics. Battery electric aircraft are projected to have a seat mile cost of around 1/4 that of existing turboprop aircraft. Maybe hydrogen can come close to meeting the seat mile cost of existing turboprop aircraft but the cost of green hydrogen will have to come down considerably. Even then, I find it hard to believe that hydrogen will ever be lower cost than battery electric. Maybe if we get high temperature fast nuclear reactors and high temperature hydrogen generation. But that would not happen before 2035 at the earliest.

Meanwhile, we will have to see if the battery electric Eviation Alice aircraft is successful. They also have a number of pre-sale orders and have been flying for 5 or 6 months but the plane has only about 9 or 10 passengers and a range with a 30 minute reserve of 250 nm or about 460 km with existing lithium ion batteries.



My ignorance of the certification process is profound.

Apparently there are 8 different authorities who can confer certification in different regions, although I don't know if certification in one means certification in all, or whether they have different views.

So that it is by no means clear, to me at least, that certification by, for instance, the FAA which is the body in charge in North America is needed for flights in New Zealand, one of Universal Hydrogen's intended early markets, or how the certification in the two regions compares, as these are short haul aircraft not long haul which would cross from one authority to the other.

In addition, as these are modifications of authorised aircraft, I have no idea how th differing (?) certifications for drive train modifications work .

Obviously they are all going to be trying to ensure safety, but there are all sorts of possible standards for safety, and it is by no means clear, at least to me, that these will be identical and universal.

If anyone can give any insight into how the whole things works, and whether it is likely, for instance, that Universal Hydrogen may be able to convert substanstantial numbers of aircraft at least in some regions of the world for internal use without going through the full rigors and presumable very high standards of universal certification, if there is such a thing, by for instance, the FAA, that would help enormously.

IOW I have no idea how realistic their timetable is, as I also have no idea what level they have to meet , or where.



Where the range and payload of battery electric works, that is the way to go, and 'that will do'

Better batteries will of course increase that, when and if they arrive.

Still short of SAF but clearly able to offer a lot more range and payload are fuel cells.

Radically new tech is difficult to predict, so I am still somewhat less than fully confident of the practicality of the specs needed in the fuel cells, although things are looking pretty good, from Universal Hydrogen and Hypoint.

The bit I am way more confident about is the cost reduction curve for somewhat more established technology.

Why I did not fancy and was wary about battery cost projections was that radically different tech was needed , lithium air, sodium sulphur, whatever, and you can't read that from rates of decrease for lithium ion.

I am a lot happier, although not totally confident, now that some cheaper and more energy dense technologies have got going a bit more.

For hydrogen OTOH, without breakthroughs assumed IMO we are already, and have been for some time, at a point where we can make predictions for cost with a high degree of confidence based on cost reduction and increased volume curves.

I would argue that we are pretty much at the same point in the curve as happened for lithium ion batteries some years ago, and we can count on massive increases in volume and substantial falls in cost for many years to come.

That is assuming no breakthroughs, as for instance naturally occuring hydrogen, pyrolysis, or hydrogen from seawater might result in extraordinarily low costs for hydrogen,, as against simply far cheaper than at present in a business as usual scenario.

But then of course I might be wrong! ;-)



I tried to answer this before but it disappeared into the ether.

Anyway, I know some about the FAA but I am not an expert on certifications. I am building STOL (short takeoff and landing) kitplane and own a share in another kitplane that is flying and try to fly each week . These are considered experimental and are not certified aircraft. You can modify these planes or and build your own design. You do need to pass an airworthiness inspection and fly off 40 hours of testing in an designated limited area before carrying passengers or flying in other airspace. You also can not use experimental aircraft for commercial operations.

Certified aircraft are another matter. They are subject to considerable bureaucracy. A good example is the use of leaded fuel. It was supposed to be phased out years ago and while there are working substitutes, it now not supposed to be phased out until 2030. And if you have a certified aircraft, you need to have paperwork called an STC to use a substitute fuel and you have to purchase the STC. BTW, both the plane that I am building and I fly use unleaded fuel. Anyway, I hate to think of the hoops that you would need to jump thru to use hydrogen. It is true that they do not need to go thru a zero start certification for the airframe but they will need to certify all modifications. I really doubt that they will accomplish this in the 2025 time frame. 2027 or 2028 or maybe never. You need deep pockets for this game.

Have to see how Eviation Alice does with the battery electric certification, I really doubt that they will be certified to carry paying passengers by 2025. They are flying but are well over a year past earlier projections.


Hi sd.

Great insights as usual, and fascinating that you are involved in two builds!

Things on leaded fuel may be moving rather faster in Europe, although for personal aviation the somewhat endearing trait of so many of my American friends of assuming that what goes for the US, goes for the rest of the world is in fact fairly substantially true.

Here is a link to what the powers that be are up to here on it though:

Getting hydrogen certified is no doubt a fraught process, and I am equally sceptical that the timelines laid out by Universal Hydrogen are practical.

But both they and Zero Avia have serious aerospace backing behind them, who are hardly naive about the process.

The bottom line is, I dunno - and you can quote me on that! ;-)

For very light aircraft of the order of trainers the fuel costs of batteries sound unbeatable, providing you have not got ambitions to go very far....

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