I have estimated that an Airbus A320 generates something on the order of 80 MW during takeoff. A hydrogen-powered aircraft, for the same freight load, will have benefit of efficiencies not available to an A320, so the needed power will be less, but I don't know how much less.

The 0.5 MW system described looks like a good first step, but should be scaled up quickly. Results will be immediately useful for co-generation and energy storage on terrestrial power systems. For at least the next decade, that will be its only benefit, which may come to overshadow its aviation application, particularly if the latter encounters snags.

If I understand correctly, this makes use of a hydrogen fuel cell for electric power, and then has that turn electric fans.

In general, a modern fuel cell is ~60% efficient at turning chemical energy into electricity, and an electric fan is ~4x as efficient at turning electricity into thrust when compared to a turbofan engine turning chemical energy into thrust.

So ignoring transmissions losses (which would probably be really low anyway if ran on superconductors...) you'd need about 40% of the power of a modern jet to do the same work. There is clearly a lot of scaling work needed, and I don't see a fuel cell/electric aircraft beating existing ones anytime soon if you ignore the emissions, but at least this clearly shows that there is a future for mass commercial aviation once burning carbohydrates is no longer acceptable.

The failure modes are going to be interesting, to say the least...

Yeah, It would be great if any fires were to burn clean and had a strong tendency to rise away from the aircraft, particularly for ground fires. H2 is also nice in that it doesn't create a lot of infrared energy while it burns.

You might be able to save the weight of any fire suppression systems.

I think OP meant that electric motor losing superconductivity in-flight will cause irreversible run-away heating of the motor. Which must be mitigated by having more motors than nominally needed, all with independent power supply and cryogenic contours.

The way I see it, losing superconductivity instantly shuts down the motor by tripping the circuit breaker, and causes it to transfer it's momentum energy into the surrounding liquid hydrogen. Some hydrogen might boil off, but it's nothing a safety valve can't handle.

The plane can then glide to the closest airport or switch to a non-superconducting mode.

If anything, losing superconductivity will cause less current to flow, since the resistance will increase greatly, and a massive amount of heat will be created.

This makes no sense to me. Don't you also need cryogenic systems to keep the H2 cold? Wouldn't those use waaaaay more energy than what you save with superconducting motors? Maybe they are talking about short haul flights where the H2 is ground cooled and then used as a cold sink but then in order to keep your electronics cold you're carrying lots more fuel than you need. TFA was too thin to pass the sniff test.

> Don't you also need cryogenic systems to keep the H2 cold? Wouldn't those use waaaaay more energy than what you save with superconducting motors?

Probably not. Cryogenic liquids like liquid H2 are typically stored in dewers, which use a vacuum as the primary insulation, along with silvered surfaces and layers of mylar film to reduce radiation losses. We've been able to make dewers with boil off rates of 1% per day or better for decades. That's more than low enough that you don't need any refrigeration at all for an aircraft application where the flight just lasts a few hours anyway.

Most likely they'll actually use less effective insulation to save weight. Fortunately for them, cryogenic liquids are commonly used in rockets, so there's already lots of know-how and technology out there for making lightweight cryogenic insulation.

Motors are solid 3D structures. The more power you put in not superconducting, the more heat you have to extract. Superconductors mean you only need to keep your refrigerant cool, and that's a product of insulation effectiveness, not power output.

This is the difference between electric and combustion powertrains, no?

In electric, heat is the enemy and inefficient.

In combustion, heat is a key component of the thermodynamic efficiency, unavoidable, and effectively only limited by material tolerances.

(I didn't major in physics, so someone keep me honest on the ceiling / floor efficiency equations for combustion engines?)

You still have to cool a combustion engine - hence why car's have radiators.

Combustion engine's are also limited by Carnot cycle engine efficiency - about 64% theoretically, no more then 50% in the real world. So you're still going to wind up having to dump progressively more heat from a fixed surface area.

(Post coffee) Cars have radiators to cool the operating structure (e.g. engine block), but that cooling's ancillary to power produced, no?

Carnot cycle was what I was grasping for.

Original point being that in a thermal engine, increasing your temperature gradient by increasing your high-temperature side (while holding exhaust constant) leads to more potential power.

Or IOW, a thermal engine that doesn't burn hot somewhere isn't going to produce much power.

(Electric being a completely different ball of wax)

This is effectively regenerative cooling, like what rockets are commonly using. There are no cryogenic systems onboard, but all the fuel is loaded as very cold, and you can use the fuel as a coolant just before you burn it.

They will, however, be using kerosene, not liquid Hydrogen. It cannot provide cryogenic temperatures.

Did you read the article? It was specifically about future liquid hydrogen-powered aircraft.

The H2 keeps itself cold by boiling away. You just need some insulation to slow down the rate to something manageable. Insulation normally uses a gas such as air to block the heat flow and as a result tends to be very light.

The idea is that a large-scale LH2 flow into the system is being consumed, and perforce heated, and may be used as refrigerant on the way there. It makes perfect sense.

Rockets do this today, as indeed they have done from the earliest days, sending liquified gases through channels in the engine bell and combustion chamber before burning, keeping them both from vaporizing.

Here, the very high efficiency of electric-driven turbines is offset by the lower efficiency of fuel-cell generation, for what is expected to be a substantial net gain over burning H2 in internal combustion turbines.

The latter are the obvious first stage of deployment, taking advantage of LH2's extreme energy-to-weight ratio for reducing the takeoff fuel load by as much as 5:1. This form will probably be fielded in existing airframes, displacing some cargo space with in-hull LH2 tanks.

Aka regenerative cooling: https://en.m.wikipedia.org/wiki/Regenerative_cooling_(rocket...

You use the boiloff hydrogen in the power source, I assume a fuel cell in this case.

This is regularly done by LNG tanker ships. Evaporating LNG is simply routed to the engines.

I think the idea is to use the H2 both as fuel and refrigerant.

So you recover the boiloff and use it to power a generator which powers a drivetrain cooled by the liquid hydrogen. This seems like a good idea.

Liquid hydrogen can do cool things, but how do you reliably stop leaks of the smallest atoms in the universe, even if they are supercooled?

making it stick to itself

Cool idea. I would be more enthused if it came from another company though. It seems like all the "green" projects Airbus does are aborted.

Remember their last electric plane? Canceled before the first flight. Meanwhile a couple startups are successfully retrofitting electric propulsion on light aircraft.

>"Liquid H2's key drawcard to aircraft designers is its impressive energy density by weight, but Airbus believes there are serious opportunities to be explored in another of its properties: temperature. To keep it liquid, it needs to be stored cryogenically at -253.15 °C (-423.7 °F), and Airbus figures that if you've got a monster cold source like that on board your aircraft, you might as well make use of it.

The theory is that the

liquid hydrogen can supercool the entire electric powertrain down to superconducting temperatures, at which point resistance virtually disappears from the system, and efficiency skyrockets.

A powertrain designed to take full advantage of this effect, reasons Airbus, could get the same job done at less than half the weight, half the electrical losses and reduced voltages.

So it's building one. The Ascend system will be a ground-based proof of concept developed over the next three years.

It'll be a 500-kW (670-hp) powertrain

, with cables, controllers, electronics and motors that are cryogenically cooled by liquid hydrogen pumped around in a circuit from the fuel tanks."

PDS: Seems like this could have electric antigravity ("electrogravitic") applications -- but as of this point in time, the theory of exactly how to do that seems lacking...

Still, the immense power (500-kW) and superconductivity aspect of things, seems to be there -- perhaps what's needed is for someone or some group to do some electric anti-gravity experimentation with this infrastructure...

Can they get weight loss electrically -- even as little as an ounce -- using all of that electricity and superconducting apparatus -- in some new, novel fashion?

?

Electrogravitics is pure pseudo-science, anti-gravity bullshit, not supported in any way by our current understanding of physics or any experiment.

However, superconductivity (and using liquid hydrogen both as energy source and coolant) may be useful for ion thrusters; see:

-https://www.researchgate.net/publication/245438424_Supercond...

-https://www.nasa.gov/directorates/spacetech/strg/vitucci.htm....

>Electrogravitics is pure pseudo-science, anti-gravity bullshit, not supported in any way by our current understanding of physics or any experiment.

YouTube begs to differ:

https://www.youtube.com/results?search_query=antigravity+ele...

Not sure if this is a joke, but I'll bite.

Those are called ionocrafts. They work by ionizing air particles. They're basically low-tech ion drives. They don't work in vacuum.

>Not sure if this is a joke, but I'll bite.

Everything in the Universe (paradoxically I might add!) -- is both deadly serious -- and a highly humorous joke!

It is also neither!

What anything is (terrible, funny, neither) -- depends on the perceiver's understandings in the matter...

Simple example: A long time ago, The Common Cold was not well understood -- and people often died from it (the term is called "The Chills" in Victorian Literature).

The Common Cold -- back then -- was a highly serious matter!

You didn't joke about it, you didn't make fun about it -- it was not socially apropos to do so!

But these days, well, you can make all of The Common Cold jokes you want -- nobody will bat an eye... but they probably won't be all that funny (that is, they'll fall into the 'neither' category!).

The time that Common Cold jokes would have been the funniest -- would have been at the time where cures for The Common Cold were being discovered -- and half of the population knew about them, but half didn't!

You see, then a bunch of renegate doctors (who were in the know! ("Take more Vitamin C" -- or whatever!) -- could have made fun of it with a bunch of other renegade doctors (who were also in the know!) -- and the joke would have been actually funny! To them, with their understandings, at that time!)

But, it's more neutral these days... since everyone knows, and no one cares...

But all humor or seriousness (or neither!) -- is relative to the proverbial "eye of the beholder"...

>Those are called ionocrafts. They work by ionizing air particles. They're basically low-tech ion drives. They don't work in vacuum.

This is an excellent response -- because this response raises several questions that prior to it, I didn't think of asking! They are:

1) Are we really sure that electric-only (no gas, Krypton, Xenon, or otherwise) propulsion doesn't work in the vaccuum? Sure, we could take an arbitrary scientist's word for this -- but I'd much rather somehow get to space -- to test it for myself.

OK, so now, let's suppose that that doesn't work...

If it doesn't -- then we now need to analyze the difference between a gas-based (Krypton, Xenon, etc.) ion thruster that does work -- and a purely electric one that we speculate does not.

Now, I'll do a quick version of that in my mind...

See, the difference is that we're accelerating actual particles of matter, gas to be precise, (Xenon, Krypton, etc.) -- at very high speeds out of a nozzle; the electricity is used for generating radio-frequency waves in a cavity (similar to a microwave oven) -- which in turn excites and accelerates the gas (which in turn is directed by the cavity and/or magnets and/or electromagnetic fields in that cavity...)

That's one of the directions of the movement -- but we're interested in the opposite direction -- the direction of the thrust.

So what does that get down to?

Well, the Xenon, Krypton -- are not at pressure; that is, unlike a conventional rocket engine -- there is no pressure from the expansion of the gas in a chamber!

So what else might be going on?

OK, here's the thing:

As far as I can tell, at this point in time -- everything in a gas-based ion drive that DOES work in outer space -- is based on INERTIA.

Basically, somehow (and science needs to study this more!) -- there's an INERTIAL LOCK between the Krypton or Xenon particles -- and some/all other parts of a functioning gas-based ion drive!

Think of it this way, you're climbing up a rope, the rope goes down (relative to your position), you go up, (relative to the rope).

Your hands have an INERTIAL LOCK -- on the Rope!

Well, same thing in the working ion thruster -- but all or part of that machinery -- somehow has an INERTIAL LOCK (magnetic, RF, or otherwise!) -- on the Krypton or Xenon particles!

That's important -- because see, if you understand that, the next step is the following question:

2) What else can we gain an INERTIAL LOCK on? Can we gain an INERTIAL LOCK on smaller gas particles? What about water (I believe this is already proven in submaries that use electricity to move water).

But but... the real grand-master Physics question (after answering all of those becomes something like):

3) Can we gain an INERTIAL LOCK -- ON SPACE ITSELF?

?

Now, at this point in time -- I don't know the answer to that!

But, a great response -- as I wouldn't have considered thinking of these questions, or writing this, without it!

While there might be something to the underlying tech the current two most promising paths to carbon neutral airlines are synthetic fuel generated with green energy and better batteries. It's highly unlikely that exotic, barely developed hydrogen tech that's not even made it to the "tech demonstrator prototype" phase is going to work exactly the way they're hoping in the end. A few % here and there from unexpected circumstances tends to make a big difference in viability, especially in situations where engineering margins or economic margins are thin (both apply to commercial flight).

[superseded]

Yeah, people don't like being told they fell for exactly what the editor who chose the title wanted them to fall for.

No, ignorant editorial bloviating is specifically forbidden in the ToS.

The article is clearly greenwashed with respect to the potential impact of the tech (it's at such an early stage lord knows where if any applications in which it will be used). This is corporate press release SOP. Calling it out as wasted words to be ignored or disregarded isn't "editorial bloviating".

And they're guidelines, not a ToS.