Ultra-light liquid hydrogen tanks promise to make jet fuel obsolete
newatlas.com
newatlas.com
Even a magically zero-weight airliner hydrogen tank will be physically huge. Just compare cross-section diagrams for rockets running kerosene/oxygen engines with rockets running hydrogen/oxygen engines. (Use the oxygen tank sizes as your reference standard.) Now recall that jet fuel is basically kerosene, most of which is stored in tanks in the wings - where cylindrical liquid hydrogen tanks would be a poor fit. Huge cylinders added to an aircraft will also add huge drag, or eat up much of your passenger/cargo space.
EDIT - OOPS, I didn't spot the article's emphasis on cryogenic (liquid, at 20 K, −253 °C or −423 °F) hydrogen. Ask a rocket scientist how safe, easy, and cheap that stuff is to handle. Current rockets mostly use kerosene instead, in spite of kerosene's far-worse efficiency in $millions-per-launch rocket engines, to avoid dealing with liquid hydrogen.
There's some concepts that may work around that, like a blended-wing design. Airbus seems to think it's viable.
https://www.airbus.com/en/innovation/zero-emission/hydrogen/...
Also, a hydrogen fuel cell based plane could be designed to fly much more efficiently than a regular turbofan plane. For instance, something like the Maxwell X-57 where you have very thin, low-drag wings, and use small electric propellers to provide the extra lift needed during take-off and landing.
Electric propulsion enables new designs that wasn't possible with turbofans, and I'm sure electric planes will end up looking quite different from todays planes. But it'll take a couple of decades to figure it out.
My point: Your "much more efficient" looks correct, as language to use among informed engineers. But risky to use around managers, customers, etc. - who'll quickly develop fantasies of around-the-world jumbo jet flights, powered by the hydrogen tank in their carry-on duffel bag.
But one of the biggest advantages GP was getting at is plumbing. Moving fuel around an aircraft is non-trivial and heavy. It's just not feasible to slap a dozen engines of various sizes on each wing. Running a power line to an electric motor is a lot more doable to put it mildly. That has massive implications for aircraft design and opens up a lot of further more efficient wing designs for example.
Long haul aircraft will definitely be last if ever (it's perfectly possible to make green synthetic hydrocarbon fuel directly from atmospheric CO2 which in turn is carbon neutral, for niche applications where it's worth it we can move from fossil fuels without moving from hydrocarbons). For short/medium haul though the volumetric energy density of hydrocarbons doesn't necessarily need to be remotely matched.
Although all that said, I don't think hydrogen is going to play a role there long term anymore than I think it will anywhere else. Batteries have the ceiling and have too many network effects at this point, and syngas is close to as green as hydrogen (more non-global warming pollutants in use) while being what we're already use to working with. Only place I really see hydrogen having a niche is space, but even there it's not clear the ISP advantages will ultimately be worth it vs the vastly easier to store/refuel methane.
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0: https://new.abb.com/news/detail/1789/ABB-motor-sets-world-re...
Why would you convert the hydrogen to electricity instead of burning it in the jet engine?
I'm not super familiar with cargo aviation, so I'm not sure how often are aircraft weight limited, as opposed to volume limited. In the former case, the low density of hydrogen would probably be less of an issue.
Kerosene is used because it's better, moreso than the difficulty of handling. Kerosene is basically ideal for the first stage, and is a great second stage choice if you aren't going to very high energy orbits. Hydrogen's economics are mostly terrible.
Or maybe ships and planes could use it to reduce speed, as when an aircraft comes into land, or a ship coming into port.
Though with that amount of power batteries wouldn’t be able to charge fast enough, and super capacitors would be added complexity.
There's no need for a capacitor when you have gravity and altitude.
OTOH, if we manage to make SSTO practical, we can think of single-stage suborbital passenger carriers, which are much more interesting than using Starship for that.
https://en.wikipedia.org/wiki/Reaction_Engines_LAPCAT_A2
Rawrrr
Unless they left out the word "thousand" after the word "several", this technology doesn't seem too close to market.
What will inevitably be what happens is that battery systems will be charged at airports and be in some standard format that can be swapped not unlike the lifts that do food or luggage.
Another one: https://www.bbc.com/future/article/20210401-the-worlds-first...
And this one was built in 1988: https://en.wikipedia.org/wiki/Tupolev_Tu-155
I also find it hilarious that 7,000ft is an achievement.
Meanwhile, electric planes have literally went around the world. https://en.wikipedia.org/wiki/Solar_Impulse
How soon do you think solar aircraft will be doing commercial passenger flights?
So you disproved your own argument and are only arguing over semantics?
https://www.electrive.com/2021/02/02/fraunhofer-develops-hyd...
Would the tanks need to go in the main fuselage, or would this be a chance for flying wing designs to be used?
Gas turbines themselves have no problem with hydrogen as a fuel, it's just the burners/fuel injectors/flame holders that need appropriate adjustments. Also, they can fly higher, because hydrogen is more flammable and will burn even in extremely lean mix that happens at very high altitude.
I initially saw their comment as meaning adapting the existing engines to use hydrogen. I see now that they might just mean using engines designed for hydrogen, not the jet engines we have today that use jet fuel.
Yeah, the gas turbines would be easy to convert compared to jet engines.
Fuel cells are potentially more efficient though.
Hypoint is developing the fuel cells, and they’ve partnered with someone else on the tanks. Electric motors for small planes don’t appear to be a challenge. Beta technologies out of Burlington Vermont is flying electric planes with lithium batteries today. So in that case, it is really about switching the energy source for the plane.
I think what’s missing is all the hydrogen infrastructure to get cryogenic hydrogen to the runway. But that’s a classic chicken and the egg problem.
Also, old intercontinental supersonic flights aren't done anymore, the Concorde is gone and nothing replaced it. It will likely never be an economically viable niche, particularly since the utility of video streaming has been so conclusively demonstrated, soaking up much of the demand for business travel.
We can see a flame from kerosene, but kerosene burns slowly. We can't see a flame for hydrogen, but it is gaseous and burns so fast that it essentially detonates. Given that small timescale, that means we wouldn't be able to act on that information (seeing a flame) anyways.
My reply was focused why we wouldn't use this for cars and trucks. While fuel containers tend to be well protected on newer vehicles, the number of accidents on the roads still sees some ruptures/fires. The hydride tanks tend to be a better option since they will just smolder as the gas escapes slowly, compared to liquid hydrogen tanks which practically detonate either from the rapid release of the pressure or from the rapid deflagrenation (which occurs at a much lower flashpoint than gasoline).
The main thing is batteries are too heavy (cars and trucks shouldn't fly) and this is the best solution of a lot of less dense energy choices.
But a low-speed piston seal that only has notable pressure across it during active roll maneuvers (centripetal force from the roll-rotation) and uncoordinated turns, between LH2 and gaseous H2 with the latter slightly warmer than the former... it's not like you'd want the empty part of the cryogenic tank to be at non-cryogenic temperatures or filled with something that'd contaminate your LH2.