Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

ZEROe: Hydrogen-hybrid aircraft concept

airbus.com

Post reply on HN
Print view View original

91–100 of 111 posts

Re: ZEROe: Hydrogen-hybrid aircraft concept

#91

Post by jakozaur »

largolagrande wrote: post #82
jakozaur wrote: post #76

Would not be easier to produce synthetic kerosene fuel from captured CO2 and hydrogen. The process is straightforward: 1. A lot of cheap solar energy, from the best location. 2. Electrolyse to produce hydrogen. 3. Capture CO2. Either from air or from carbon intensive processes (e.g. producing cement). 4. Use Sabatier reaction to bond CO2 and hydrogen to produce carbohydrate fuel. 5. Since we use same amount of CO2 to…

> A lot of cheap solar energy, from the best location. I recommend that you watch the "Planet of the Humans" documentary to understand why there is no cheap solar energy, no so-called "green" energies: https://www.youtube.com/watch?v=Zk11vI-7czE So there will never be any "green" planes, no matter if they use hydrogen or kerosen. Since the minimum required amount of energy to fly from point A to point B with N passen…

Michele Moore movies optimize for publicity, not scientific accuracy.

There are some truths in the movie (e.g. biomass would not work), but many times he is plain wrong. E.g. 8% solar efficiency, when my neighbours installed 21% one and 15% is common on utility scale. No solar panel on the market has just 10 years+ lifespan, many come with 20+ year warranty and could still produce energy afterwards with tiny decrease in efficiency.

Re: ZEROe: Hydrogen-hybrid aircraft concept

#92

Post by ib84 »

filleokus wrote: post #73
ib84 wrote: post #70

A side-question on the perspective of battery-driven electric-flights: when electric cars can recuperate power instead of breaking, why can't airplanes do the same on descent? Couldn't they build a propeller at the rear, which does propulsion and recuperation? Energy-wise, that would certainly be attractive...

My gut feeling is that it's probably not substantial amounts of energy to find there. Compared to a car in city traffic which might break to a standstill every other minute, an aircraft generally only "brakes" once when going down for landing. Further, since air resistance scales with the square of the velocity, the drag forces on an aircraft is so high that you typically never reduce thrust to zero until to just bef…

I'm no expert, so this could be wrong but I have a gut feeling that during descent it could probably idle-glide by using the high-lift device sooner. If anybody was serious about flying with less emissions that could probably save lots of energy already today - it would just take longer to reach the target. It would be interesting to see numbers how the gravitational potential energy compares to the drag forces.

Re: ZEROe: Hydrogen-hybrid aircraft concept

#93

Post by Robotbeat »

ncmncm wrote: post #51
Robotbeat wrote: post #21

Earlier quoted context omitted.

Fuel cells are better because they don't emit directly. Turns out high altitude water vapor is itself a powerful greenhouse gas. At least with fuel cells, you could collect the water and dispense it periodically as a liquid at lower altitudes. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/200... But actually, batteries are better than people think. 1000km battery-electric range is feasible with current che…

Batteries are way, way, way worse than you imagine. Their energy density would need to get >10x better, when 2x is a miracle. Furthermore, without internal combustion, you are limited to ~350 knots.

i study this professonally. batteries are sufficient if we make other improvements as well. and not true about combustion being essential.

Re: ZEROe: Hydrogen-hybrid aircraft concept

#94

Post by Aperocky »

ncmncm wrote: post #46
Aperocky wrote: post #42

Earlier quoted context omitted.

> engineer huge carbon emitters like container shipping or aircraft to run on hydrogen + solar? Why hydrogen at all then? The source is solar so let's keep it at that, why the middle state?

Really? You think solar panels on the wings would provide enough power to fly? Aircraft need concentrated energy. Batteries are nowhere near enough for anything big. Liquid H2 is the best possible fuel for aircraft, once certain practicalities are worked out, and can be produced from solar and wind.

OK So this is just about conversion.

H2 doesn't need solar, it needs power, it doesn't care where that power came from. It's essentially a disconnected system, to sell it as if H2 somehow means solar (which I get from earlier threads) is a little bit disingenuous.

Re: ZEROe: Hydrogen-hybrid aircraft concept

#95

Post by liability »

jabl wrote: post #52
liability wrote: post #41

Earlier quoted context omitted.

I believe popular proposals involve the use of algae. Regardless, farming in general is something modern civilization already has a strong competency in. Synthesizing jet fuel from scratch might make sense for the USN since they have nuclear reactors and all the water they want, but I think it's fair to say our civilization in the general case struggles with generating huge amounts of clean electricity. Plants do it…

Society uses absolutely mind-gobbling amounts of energy, mostly from fossil fuels. There's just not enough land available to produce even a significant fraction of that from biofuels. Never mind the ecological devastation that would be caused by converting the little wilderness left to intensive biofuel cultivation. That is not to say biofuel don't have a role to play. Agriculture and forestry wastes, municipal biowa…

But this is my point; biofuel makes a ton of sense for aviation. Biofuels would be used in cases where there is no realistic alternative, particularly with airplanes. It's more practical and likely to succeed in this domain than hydrogen, and isn't a total pipe dream like battery powered planes. In other domains, like grid power or automobiles, solar/wind/etc are the way to go (I never suggested we run power plants off biofuel!), but there is still a fuckton of coal and natural gas plants that need to be replaced. Trying to also replace jet fuel with synth fuel at the same time will only set back efforts to close coal and natural gas plants. If we already had a surplus of clean electrical energy then things would be different, but we don't. Every solar farm dedicated to the production of synth fuel is a solar farm that isn't replacing a coal plant.

I just don't see any way that synthesis of jet fuel from atmospheric carbon makes any sense for anybody but a nuclear Navy.

Re: ZEROe: Hydrogen-hybrid aircraft concept

#96

Post by ncmncm »

usrusr wrote: post #79
ncmncm wrote: post #47

Earlier quoted context omitted.

Hydrogen at atmospheric pressure is hard to ignite in uncontrolled circumstances. It wants a specific gas/air ratio.

Thought experiment: how close would the Hindenburg have been to missing that specific ratio? The thing is, no matter how far you are overshooting or undershooting that ratio, as soon as you are doing both there'll be a boundary where it's matching.

The Hindenburg was blown up with a bomb. The flames in the film are kerosine. Trotting out the Hindenburg weakens your case, because no H2 lofted dirigible suffered an unassisted ignition event.

The boundary, if there is any, also has to coincide with an ignition source. Furthermore, the ignited bit needs enough fuel around it to build a chain reaction.

Systems will be designed to maintain positive airflow to keep concentration, in the event of a leak, below the threshold. That is engineering.

Re: ZEROe: Hydrogen-hybrid aircraft concept

#97

Post by liability »

JAlexoid wrote: post #60
liability wrote: post #39

Earlier quoted context omitted.

> for a very specific number of hours Unless you plan on throwing away the planes after one or two flights, those tanks will be filled with hydrogen for tens of thousands of hours over their lifespan. Perhaps they have light weight alloys that can cope with this though, I'm no metallurgist..

I never addressed the lifespan of containers, that's not same as hydrogen leakage.

Hydrogen embrittlement leads to hydrogen leaks. Unless there are advanced alloys that resist it, any aircraft part that comes into contact with the hydrogen will be subject to accelerated 'wear'.

Frankly hydrogen planes are nonsense. Even if it works on paper, it's not realistic to expect all the extant planes to be rapidly phased out with brand new planes with exotic designs that aircraft manufacturers, pilots, and airlines don't have any experience with. On the other hand, old planes can be retrofitted to burn biofuel and new production planes of old proven designs can be made to burn biofuel from the get-go.

'Concept planes' like the ZEROe are basically just science fiction meant to wow shareholders and give the public the impression that legislative reform isn't necessary because corporations are already taking the problem seriously. I don't think these are serious proposals, it's just corporate propaganda. Car companies pushed hydrogen cars for years for the same reason. Hydrogen fuel cell cars were never going to happen for a myriad of practical reasons and car manufacturers knew it but promoted the concept anyway for PR reasons. ZEROe is Airbus doing the same.

Re: ZEROe: Hydrogen-hybrid aircraft concept

#98

Post by ncmncm »

Aperocky wrote: post #94
ncmncm wrote: post #46

Earlier quoted context omitted.

Really? You think solar panels on the wings would provide enough power to fly? Aircraft need concentrated energy. Batteries are nowhere near enough for anything big. Liquid H2 is the best possible fuel for aircraft, once certain practicalities are worked out, and can be produced from solar and wind.

OK So this is just about conversion. H2 doesn't need solar, it needs power, it doesn't care where that power came from. It's essentially a disconnected system, to sell it as if H2 somehow means solar (which I get from earlier threads) is a little bit disingenuous.

Not even a little bit. Wind and solar are the cheapest source of power, with their usability reduced only by surge demands. Liquifying H2 would absorb peak production and be unaffected by temporary lulls.

Unless you think it would be natural to use the more expensive power instead?

Re: ZEROe: Hydrogen-hybrid aircraft concept

#100

Post by liability »

ncmncm wrote: post #44
avmich wrote: post #40

Earlier quoted context omitted.

> Let plants deal with the CO2, since they're good at it They aren't good with it at all. Convert CO2 slowly, take space to do that, take other resources like fertilizers, require some shielding from pests and herbs, can produce massive fires... They have advantages, but it's not a silver bullet, especially when you're in a hurry.

Maximum efficiency of 2%. Even the worst electrolysis driven by cheap solar does better.

You've forgotten that we have a limited capacity for solar cell production and those solar cells are put to better use replacing coal plants than synthesizing something plants can synthesize.
Post reply on HN