ChatGPT & DALL-E generated panoramic image of an ATR 72 with hydrogen written on the side abandoned in a weedy field beside an airport, covered in dirt and pigeon droppings

Another Day, Another Hydrogen Transportation Firm Plummets To Earth

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After a brief period when hydrogen for energy and transportation plays managed to mostly limp along without failing entirely, apparently it’s time for another spate of bankruptcies and closures.

A few days ago, it was Hyzon’s time to admit failure. Having gone public via a reverse takeover SPAC, the firm suffered the usual SEC investigations, gave over $25 million to the SEC to settle, and expanded to multiple countries. Then it contracted back to solely the USA and most recently admitted it was considering putting itself up for sale, although it is unclear what assets they have worth buying.

Now it’s Universal Hydrogen, the aerospace startup that wanted to create Nespresso pods full of hydrogen for aircraft. It was a terrible idea from the very beginning, which shows using very little math. The firm was founded in 2020 by Paul Eremenko, the former CTO of Airbus and United Technologies, and Jon Gordon, with the mission to decarbonize the aviation industry through hydrogen-powered flight. The company garnered significant interest and investment, raising over $85 million from prominent investors like Playground Global and American Airlines.

More specifically, they were trying to jam hydrogen into the form factor of aircraft baggage containers, often referred to as Unit Load Devices (ULD). That’s a nice concept, as it would allow the ULDs to be shipped just like any other pod of cargo to be put into luggage compartments of airplanes. Unfortunately, the physics doesn’t lend itself to anything remotely resembling range, and the operational challenges and costs approach the status of a brick wall.

I hadn’t bothered to do the math on this when I saw it, as it made zero sense. The only way to get enough hydrogen into an airplane for range is as liquid hydrogen and even then it isn’t very dense. Liquid hydrogen has a volumetric energy density of approximately 8.5 MJ/L, which is about a quarter of Jet A kerosene’s volumetric energy density of about 35 MJ/L. I’d assumed that they’d be doing that and dismissed it on the grounds that delivering highly insulated, small, non-spherical pods of supercooled hydrogen that was boiling off at every step of the way would just fail. I didn’t bother to do an analysis because it was so obviously a broken idea.

However, it turns out they were actually going with compressed hydrogen, a complete non-starter. Their initial target aircraft, the ATR 72 regional turboprop, typically carries 5,700 liters (1,500 US gallons) of Jet A fuel.

Assuming an AKH container, often used with ATR 72s per what I can see, with high-tech composites capable of containing 700 atmosphere pressures, that provides an interior volume of just over 3 cubic meters. That could hold about 130 kilograms of hydrogen. A couple of their pods would both displace about two-thirds of the rear luggage space and only contain about 260 kilograms of fuel.

A kilogram of hydrogen has about the same energy a US gallon of gasoline, and slightly more than a US gallon of Jet A. A modern turboprop is about 30% to 35% efficient at turning Jet A into rotations of the propellor, which has its own efficiency concerns. A fuel cell is more efficient, 50% to 60%. That means a fuel cell hydrogen aircraft, all else being equal, would get about 70% more range from the same energy in the fuel. Those 260 kilograms of hydrogen are like 440 or so US gallons of Jet A, or about 29% of the gallons.

That’s good for perhaps 2.5 hours of flight time. Take 30 minutes off of that for reserve, so two hours of flight time. Take 45 minutes off for divert, so one and a quarter hours. That’s about 625 kilometers.

Of course, that’s not the end of the story. The AKH-sized hydrogen tanks likely weigh in the range of 3,000 kilograms each when empty, scaling up from the Toyota Mirai and taking weight off for a better volume to tank ratio. Containing 700-atmosphere pressure doesn’t occur with a bubble. That’s 6,260 kilograms in the rear of the plane.

The maximum payload of an ATR 72 is 7,400 kilograms. So that leaves 1,140 kilograms for passengers and luggage. That means about 14 passengers without any luggage.

What about if they get really special with ultra-light composites and shave half of the weight off of the tanks, so 3,260 kilograms for the fuel and tanks and 4,140 kilograms for passengers and their carry on luggage. That’s only 50 passengers without luggage in a plane designed for 72 people. Assuming they brought carry-on luggage, that’s down to 46 passengers. That means a full third of the passengers the plane is designed for couldn’t be carried.

Oh, and the plane would be seriously heavy in the rear, so massively out of trim. It probably wouldn’t fly like that. You could use a smaller AKE container designed to fit in the front cargo facility and avoid the trim problem, but you’d lose 25 kilograms of hydrogen in the process, which is to say 10% of the range. That’s down to about an hour of flight time. You would be able to add a few passengers.

Of course, that comes at a price. Now you have to have all of the hydrogen fuel lines and safety measures going to the front and back cargo holds. And the front cargo hold is going to suffer the brunt of accidents including gear collapse. Ratchet up the weight and safety provisions again.

We’re down to an hour-long flight with two-thirds of the passengers. Are there any other concerns? Yes, expense.

Absurdly high-tech, ultra-lightweight, ultra-strong, 700-atmosphere tanks won’t be cheap, and Universal Hydrogen was going to have to build enormous numbers of them, with most of them not in planes at any given moment, but in one of the many steps of the fuel cycle. They would be being charged in Universal Hydrogen facilities near airports, or on trucks to the airport, stockpiled in the airport awaiting loading onto planes, stockpiled empty in airports awaiting return to Universal Hydrogen facilities and on trucks empty being returned to Universal Hydrogen. Then there are the spares and replacements. It’s likely that for every hydrogen tank on a moving aircraft, two to three would be sitting around.

The estimated cost of a 700-bar hydrogen tank the size of an AKE container is approximately $30,000 to $60,000, considering the materials, manufacturing, and additional costs for design and certification. This is a rough estimate, and actual costs would vary based on specific design requirements, economies of scale, and advancements in manufacturing technology. That’s going to be amortized over the lifecycle of a tank, so might work out okay, but it’s going to be a huge capital cost just for tanks.

Then there’s the hydrogen itself. One of the many silly things about hydrogen for transportation is the assumption that it will be dirt cheap. Assertions that it cost $1 per delivered kilogram have been rife in the space, when the current cheapest delivered hydrogen is made from natural gas, put in pipelines at the facility, and delivered to industrial scale facilities that require it. That costs $7 to $9 per kilogram. It’s never going to be cheaper than that.

The cost of manufacturing green hydrogen will be reasonable in some places where there is lots of wind, water, and solar power, under $5 per kilogram, perhaps under $3. But they are going to be a long way from airports, those costs are quite a bit higher than hydrogen made from natural gas without carbon capture, and shipping hydrogen will make up for the low costs of manufacturing the stuff. With tank cost, labor, etc., it would cost a minimum of $10 per kilogram — absolute best case scenario — delivered in one of Universal Hydrogen’s tanks. 260 kilograms would cost $3,900. Jet A hovers between $2 and $3 per gallon, 20% to 30% of the likely best case cost of hydrogen.

That’s an extra $65 of costs for each paying passenger, which will add up quickly given the much lower revenue per flight due to the weight of the tanks.

Anything else? Yes, this idea depends on baggage handler systems loading fuel into aircraft, which means the baggage handlers who operate them. Fueling truck drivers at airports are typically more highly trained and certified than baggage handlers. The handling of aviation fuel requires specialized knowledge and skills, including a thorough understanding of fuel systems, fuel types, and the specific procedures for safely refueling various aircraft. Due to the high risk associated with flammable substances, fueling truck drivers must comply with stringent safety regulations, often requiring certifications and regular refresher training. They usually need to obtain specific certifications from aviation regulatory bodies and may need hazardous materials (HAZMAT) endorsements on their commercial driver’s licenses (CDLs). The refueling process involves complex procedures to ensure fuel quality, avoid contamination, and prevent spills or accidents, necessitating a higher level of training compared to the duties performed by baggage handlers.

While baggage handlers also undergo training, particularly in safety and equipment operation, the complexity and risk associated with fueling operations require more specialized training and certification for fueling truck drivers. Loading containers full of highly pressurized hydrogen would not be trivial or without significant safety precautions. If my numbers are right, 130 kilograms of 700-atmosphere hydrogen has a potential kinetic energy equal to 174 kilograms of TNT, so if the tank fractured, it wouldn’t be pretty. Baggage handlers would have to be trained and certified, adding significant personnel cost.

Of course, this pales in comparison to the chemical energy in 130 kilograms of hydrogen, which is equivalent to about 4,400 kilograms of TNT. This is less of a problem in the open air, but it’s really a concern inside aircraft, especially sealed and pressurized ones like the ATR 72. There is no odorant that works with hydrogen and doesn’t destroy fuel cells, so it’s odorless and colorless. The flash point is low and the range of explosive percentages of air is high, so it would be fairly easy to fill a plane with enough hydrogen to be ignited by a coffeemaker.

That’s why there is no reasonable path to certification for hydrogen in civil aircraft. While FAA and EASA staff love the challenge of thinking of all the ways that hydrogen in an aircraft could go wrong after decades of same old, same old, the end result is extraordinary safety measures from manufacturing to maintenance to operations that will be very expensive.

Fewer paying customers. Much higher fuel prices. Much higher personnel costs. Very high certification costs. These have been very obvious problems with hydrogen for aviation for decades, at least for anyone willing to pay attention. There is a reason why every manufacturer is certifying their aircraft on biologically sourced sustainable aviation fuel, flying flights with it, and generally getting on with business. All it takes is a bit of math and a bit of thought. There’s nothing about hydrogen that’s going to change, because this stuff is all basic physics. Aerospace firms aren’t going to innovate past these issues because they are hard limits.

That Universal Hydrogen has failed after spending $85 million is par for the course and inevitable.


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Michael Barnard

is a climate futurist, strategist and author. He spends his time projecting scenarios for decarbonization 40-80 years into the future. He assists multi-billion dollar investment funds and firms, executives, Boards and startups to pick wisely today. He is founder and Chief Strategist of TFIE Strategy Inc and a member of the Advisory Board of electric aviation startup FLIMAX. He hosts the Redefining Energy - Tech podcast (https://shorturl.at/tuEF5) , a part of the award-winning Redefining Energy team. Most recently he contributed to "Proven Climate Solutions: Leading Voices on How to Accelerate Change" (https://www.amazon.com/Proven-Climate-Solutions-Leading-Accelerate-ebook/dp/B0D2T8Z3MW) along with Mark Z. Jacobson, Mary D. Nichols, Dr. Robert W. Howarth and Dr. Audrey Lee among others.

Michael Barnard has 764 posts and counting. See all posts by Michael Barnard