370-mile hydrogen-electric seaplane set to clean up island hopping

> Do fuel cells deliver enough instantaneous power that batteries do, for the weight of all the associated equipment?

I don't know about planes, but fuel cell cars have batteries, although smaller ones that EVs, which are actually used for the motors. HFC cars are basically EVs plus the hydrogen system.

Without having specific numbers in front of me, yes fuel cells are delivering comparable power as batteries. Plus the hydrogen is lighter than batteries.

Combusting may save on some of the complexity fuel cells but you are losing efficiency in heat losses, both from the act of combusting and with gears that deliver the power to your wheels or propeller.

Almost all flying boats (seaplanes which have a fuselage for a hull instead of floating landing gear) in the past 50 years have been built with fiberglass hulls for this exact reason. Aluminum has a durability problem more than a corrosion problem, and steel has a weight problem and a major corrosion problem. At the speeds that they hit the water, anti-corrosion coatings don't last long, and with a non-amphibious flying boat, repainting requires a haulout, which is very expensive.

To guess, I'd suggest it might be mostly due to the types of electric motor already produced and available in an appropriate weight and configuraton. Further it might be that redundancy in electric motors might be more of an issue (?) and here, I wonder if they've cracked some added efficiency with having a more consistent flow over the breadth of the wings?

> Aerodynamically, having fewer but much larger props would make more sense for efficiency,

Source?

I can think of a lot of flight reasons many small props could be better. You can spin faster while still keeping the tip subsonic. Typically fans have inefficiencies because outter blade moves so much faster than the inner blade & this effect is reduced with smaller blades. If you're looking for a blown wing effect you get much more surface area. Airflow is smoother because prop wash is more dispersed and even.

For a while it seemed like many props was the sure way forward. It's definitely less seen now, but for example the Aurora XV-24A LightningStrike, NASA X-57 Maxwell, and GL-10 Greased Lightning seemed like they were setting the way forward. It seemed like technical difficulties that beset the Maxwell team that made them reduce Maxwell to a less ambitious more conventional electric offering. https://www.nasa.gov/stem-content/x-57-electric-airplane/ https://www.defensenews.com/digital-show-dailies/sas/2017/04...

I can think of some possible reasons. Can't kill any ground crew if the prop ends are 8 feet up. Fuel engines get more efficient the bigger you make them, so big propeller aircraft being more efficient isn't necessarily because of the prop size, but rather a side effect of engine size. Electric motors don't gain much efficiency with increased size AFAIK, so they can get away with small motors. Lots of props close to the wing would guide the air well - you don't get that giant vortex of wasted energy. Redundancy - they could lose multiple propellers. That's especially needed since some of these electric aircraft are VTOL and can't glide or autorotate in an emergency. I'm thinking of https://wisk.aero . Market constraints - this is a new application so they're relying on other industries for the motors they can pick from.

interestingly almost all of the original aircraft conceptualizations had a lot of props -- they got simplified due to the realities of drivetrain complexity pre-electrification.

redundancy is one reason, weight is another, cost is another. Lower amperage smaller motors require less copper and battery capacity, they're cheaper to produce, they can be placed opportunistically to maximize wing efficiency, and they're quite nearly COTS.

bigger props necessitate more power in a singular spot, bigger heavier motor and cooling solutions, so on and so fourth. lots of motors at lower duty cycle can reduce these burdens, and if done right may even be able to get rid of the cooling systems and associated weight entirely.

Having multiple small propellers along the wing is done for lift augmentation. See the X-57 concept plane for an example. If this is anything like the X-57, most of those propellers will feather upon takeoff.

Basically, most planes use wings that are much larger and less efficient than they need for cruising, because they need the extra lift for takeoff and landing. By introducing lift augmentation propellers which can augment lift for takeoff/landing, they can use a much smaller wing which has less parasitic drag and results in more efficient flight.

https://en.wikipedia.org/wiki/NASA_X-57_Maxwell

There are lots of different types of hydrogen production, but many of them are "clean" (or at least as clean as solar, anyway).

The main issue with hydrogen is storage and transport. It's not an unsolvable problem, by any means, but it's significantly more difficult to safely store and transport than liquid hydrocarbons, at any rate. Hydrogen requires significant investments in infrastructure around it which mostly haven't been made yet.

What's the less weird way to say vegan leather? I tried, but it was got weirder.

Pretty sure we could call an AR-15 vegan too. I think that's why it's weird.

"hydrogen fuel cells ... Not exactly sure why they don't get much more love."

Hydrogen is just pretty bad as an energy carrier, since it's so difficult to handle.

The main attraction currently is that hydrogen fuel cells are fairly efficient and hydrogen oxidation releases a lot of energy (most of it from the O2 bond, as in most 'combustion')

But if fuel cells that can directly handle more complex and more convenient hydrocarbons efficiently can be developed there will be little reason for hydrogen - maybe only cryogenic uses in rockets etc.

> I've always found this branding a bit weird, but I'm weird, as well, so there's that.

Perhaps it's because it's using a culinary term for a non culinary use. The problem is that they can't use the term "plant-based" because most vegan leather is made from petroleum. "Non-animal leather" also doesn't have the same ring.

It just means “vinyl” but it sounds more upscale than it is

Hydrogen is a terrible battery. Best case conversion to H2 is ~80%, while best case fuel cell efficiency is ~50%. That's 40% round trip while most batteries can do 90%.

That ignores losses due to leakage, but those are only a couple of percent. Also, ignore the hazards, but the cost of building safe low leakage infrastructure might exceed the cost of batteries and solar/wind to produce power. You're probably better off making H2 dynamically where you need it and just sending electrons or storing them locally in safe batteries.

There's no point building the infrastructure if there are no planes to use it, though. When cars were first invented, you bought the fuel from the local chemist, and petrol stations only came years afterwards.

Green hydrogen infrastructure is not the barrier, at least not in the sense that most people think it. Hydrogen is very difficult/expensive to transport and store. So much so that local production is likely to be solution. IOW, the airport will require electricity and water infrastructure, and will create hydrogen at the airport. So the infrastructure that is required is having small-scale electrolysis equipment on the market.

Water electrolysis will produce hydrogen. Of course then you also need to compress it. And the fuel cell itself is yet another even more woeful knefficiency. But maybe solar continues to get cheaper to the point where we don't care about the inefficiency. Not likely, not what I believe, but maybe it could work out. For a sea plane especially, it feels like you have what you need in abundance for this infrastructure: water, and open space for solar.

MIT also talked up a solar thermochemical hydrogen production system ~9 months ago, which claims a 40% efficiency. One still needs to compress that down but still a huge leap if that promise can be delivered on. https://news.mit.edu/2023/mit-design-harness-suns-heat-produ...

There is something really compelling about hydrogen, as the most energy dense fuel we can use, that is in mass abundance, that doesn't pollute. Conceptually it's very very cool. I'd love like heck to see X-33 or Venture Star designs dusted off with modern compositeaterial sciences, see something like Skylon make it to the sky. But it does seem incredibly cumbersome & hard & weighty to make infrastructure & fuel storage for. It doesn't seem likely. It seems like an illogical investment given the downsides difficulties & inefficiencies. But I still allow: maybe.

> And there’s certainly no robust H supply that doesn’t include fossil fuel to create the H gas

The government of Chile published a pretty clear national strategy to address this very issue [1]. And with Chile being on the Pacific Ocean, and these seaplanes most likely being used in islands in the Pacific, it's not hard to imagine a relatively simple solution to the infrastructure issue.

1: https://energia.gob.cl/sites/default/files/national_green_hy...

If you have electricity and water you can make H2 gas. Storing it is quite costly, so you probably want to make it on demand (like the Hybrit project will do).

If the article is anything to go by, the clue isn't as much the fuel cell itself, but the idea of having an engine that can be powered by any source of electricity. So instead of swapping out the engine for a different type, you only swap out the power storage method. If they have lithium and fuel cells now, but something else comes along later, it means a very localised change is all it takes to try it out and if feasible, put it in production.

For ICE propulsion you'd have to change a ton of things if you were to switch fuel types as the engine, the pumps, the tank, the hoses, sensors are all over the place and all have to change when you need to support a different fuel. (i.e. when switching from say, a liquid fuel to a gas or something like that) If I'm not mistaken, that's also why all the changes (not even innovation) have such small impact so far, because all they really can do is make sure that 'new' fuels behave the same way as old fuels, and new engines behave the same on the fame fuel as old engines. It's a deadlock.

There is hydrogen airport infrastructure under development, with this project aiming for commercial flights by 2035: https://aviationsourcenews.com/airport/airbus-leads-uk-hydro...

But it takes a decade to design and test a new airliner, so of course we should expect to hear mostly about the startups developing planes at this point.