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ZEROe: Hydrogen-hybrid aircraft concept

airbus.com

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Re: ZEROe: Hydrogen-hybrid aircraft concept

#61

Post by hannob »

xoa wrote: post #4

I'll admit I really don't get the fascination with hydrogen as an energy storage medium. It has to be manufactured, so how green it is depends on whatever the power input is coming from. It's not any inherently greener then synthetic hydrocarbon production, which can be produced from atmospheric carbon for zero net carbon impact, and of course has no sulfur or aromatics. It also works fine with existing engineering.…

> So why not just do full manufacture of regular fuel?

Always fascinating when people use "just" in sentences where they propose something that hasn't been done before (at least not at any scale that would matter) and that is a huge challenge.

As for the reason, my understading is that producing fuels from electricity is just very inefficient. You still use hydrogen as the first step and then add other steps to produce hydrocarbons. Using hydrogen spares a few conversion steps and you'll need less electricity (but likely still a lot).

Re: ZEROe: Hydrogen-hybrid aircraft concept

#62

Post by leoedin »

xoa wrote: post #4

I'll admit I really don't get the fascination with hydrogen as an energy storage medium. It has to be manufactured, so how green it is depends on whatever the power input is coming from. It's not any inherently greener then synthetic hydrocarbon production, which can be produced from atmospheric carbon for zero net carbon impact, and of course has no sulfur or aromatics. It also works fine with existing engineering.…

Getting the carbon is a huge problem. Atmospheric CO2 is at something like 400ppm - that's 0.04% of air. Given that most hydrocarbons contain a fairly large amount of carbon, that means you have to process a huge amount of air to get the CO2 needed for your fuel. That's before all the other process inefficiencies.

I agree hydrogen isn't the best fuel, but the round trip efficiency of any other synthesised hydrocarbon must be an order of magnitude lower - and even if solar energy is abundant, it's not so abundant we can waste 90%+ of it on process inefficiencies.

Re: ZEROe: Hydrogen-hybrid aircraft concept

#64

Post by bildung »

codecamper wrote: post #63

Greenwashing should be illegal. These concept renderings omit the basic physical facts: that hydrogen is less energy dense and therefore you need more of it. Tanks will be bigger and distances will be shorter.

Isn't the energy content per kg more important for planes than energy density (J/m³)?

Energy per kg is much higher for liquid hydrogen (122.8 MJ/kg) than for kerosine (42.8 MJ/kg): https://www.fzt.haw-hamburg.de/pers/Scholz/GF/GF_Paper_DLRK_...

So planes would look bulkier, but could actually be lighter than before.

Re: ZEROe: Hydrogen-hybrid aircraft concept

#66

Post by p_l »

ncmncm wrote: post #45
JAlexoid wrote: post #35

Earlier quoted context omitted.

The idea here is to do basically a cryoplane. Hydrogen can be generated on demand for the planes to refuel and can be stored highly compressed for that particular use case. We're not talking about using it for GA or cars. As for volume - there's a reason why they call them cryoplanes ;) From Airbus - Liquid hydrogen is used as fuel for combustion with oxygen.

Liquified. So, low pressure. Aerogel insulation makes the tanks practical. Volume on an aircraft is not expensive. Weight is expensive. Aerogel is very, very light. As is LH2. Airports can make the LH2 directly on the spot from solar and wind power, so no need to transport or refine fuels.

Cryogenic fuels also give possible efficiency boost by precooling inlet air, but that's bigger gain for Sabre-style engines (HOTOL, Skylon, etc. SSTOs) or for efficient supersonic airliners (proposed derivation of Tu-144 used liquid H2 to gain low operating costs for it's typical Ma 2 cruise speed.)

Re: ZEROe: Hydrogen-hybrid aircraft concept

#67

Post by aero-glide »

codecamper wrote: post #63

Greenwashing should be illegal. These concept renderings omit the basic physical facts: that hydrogen is less energy dense and therefore you need more of it. Tanks will be bigger and distances will be shorter.

Yes, they clearly mentioned that in the 30mins video. That's why fuel will be stored in the aft of the fuselage instead of the wings.

Re: ZEROe: Hydrogen-hybrid aircraft concept

#68

Post by neuronic »

ncmncm wrote: post #49
Robotbeat wrote: post #20

Not as helpful for reducing effective emissions as you might think. High altitude water vapor is just as big of a problem as CO2 as the lifetime of water vapor in the stratosphere is measured in years, not days or hours like it is in the lower troposphere. Water vapor is, after all, a much stronger greenhouse gas than CO2, it's just that normally its lifetime in the atmosphere is so short so as not to matter. So unle…

CO2 delivered to the stratosphere certainly stays there a long time; nothing there uses it.

The obvious solution is to plant rainforests in the stratosphere.

Re: ZEROe: Hydrogen-hybrid aircraft concept

#70

Post by ib84 »

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...
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