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ZEROe: Hydrogen-hybrid aircraft concept

airbus.com

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Re: ZEROe: Hydrogen-hybrid aircraft concept

#41

Post by liability »

avmich wrote: post #40
liability wrote: post #38

Earlier quoted context omitted.

> start from CO2 Why would that route even be taken though? Biofuel for jet engines is proven technology in limited use for many years now. Let plants deal with the CO2, since they're good at it, then process the resultant vegetable oils to produce a suitable diesel or jet fuel. https://en.wikipedia.org/wiki/Aviation_biofuel

> 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.

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 with solar energy on a scale we should be jealous of. And so what of they take a few months to do it? They take that long to grow the food you eat too and it's not like you starve for months waiting for them.

Re: ZEROe: Hydrogen-hybrid aircraft concept

#42

Post by Aperocky »

schainks wrote: post #7
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.…

This is a simplification, think about this: You can manufacture hydrogen anywhere as long as you have water, an electrolyzer, and a power source. Oil can only be pumped out of the ground in certain places, water is technically _much_ more abundant everywhere. Hydrogen storage tech has improved in the last twenty years. It's becoming affordable and "as safe" to store hydrogen at fuel densities similar to that of petro…

> 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?

Re: ZEROe: Hydrogen-hybrid aircraft concept

#43

Post by m4rtink »

outworlder wrote: post #15
schainks wrote: post #7

Earlier quoted context omitted.

This is a simplification, think about this: You can manufacture hydrogen anywhere as long as you have water, an electrolyzer, and a power source. Oil can only be pumped out of the ground in certain places, water is technically _much_ more abundant everywhere. Hydrogen storage tech has improved in the last twenty years. It's becoming affordable and "as safe" to store hydrogen at fuel densities similar to that of petro…

> It's becoming affordable and "as safe" to store hydrogen at fuel densities similar to that of petroleum based fuels. Have we solved hydrogen embrittlement issues? What about hydrogen leaking out of containers?

Not to mention hydrogen fires being invisible to unaided eye in daylight.

Re: ZEROe: Hydrogen-hybrid aircraft concept

#44

Post by ncmncm »

avmich wrote: post #40
liability wrote: post #38

Earlier quoted context omitted.

> start from CO2 Why would that route even be taken though? Biofuel for jet engines is proven technology in limited use for many years now. Let plants deal with the CO2, since they're good at it, then process the resultant vegetable oils to produce a suitable diesel or jet fuel. https://en.wikipedia.org/wiki/Aviation_biofuel

> 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.

Re: ZEROe: Hydrogen-hybrid aircraft concept

#45

Post by ncmncm »

JAlexoid wrote: post #35
outworlder wrote: post #14

Earlier quoted context omitted.

> As I understand it, the production of complex hydrocarbons that can be used as a replacement for jet fuel is even more inefficient when compared to the production of hydrogen, as many of the known processes that start from CO2 actually use hydrogen in the process. Sure. Here's the thing though: we can efficiently store those complex hydrocarbons. We can't efficiently store hydrogen. It destroys containers, and can…

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.

Re: ZEROe: Hydrogen-hybrid aircraft concept

#46

Post by ncmncm »

Aperocky wrote: post #42
schainks wrote: post #7

Earlier quoted context omitted.

This is a simplification, think about this: You can manufacture hydrogen anywhere as long as you have water, an electrolyzer, and a power source. Oil can only be pumped out of the ground in certain places, water is technically _much_ more abundant everywhere. Hydrogen storage tech has improved in the last twenty years. It's becoming affordable and "as safe" to store hydrogen at fuel densities similar to that of petro…

> 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.

Re: ZEROe: Hydrogen-hybrid aircraft concept

#47

Post by ncmncm »

m4rtink wrote: post #43
outworlder wrote: post #15

Earlier quoted context omitted.

> It's becoming affordable and "as safe" to store hydrogen at fuel densities similar to that of petroleum based fuels. Have we solved hydrogen embrittlement issues? What about hydrogen leaking out of containers?

Not to mention hydrogen fires being invisible to unaided eye in daylight.

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

Re: ZEROe: Hydrogen-hybrid aircraft concept

#48

Post by ncmncm »

usrusr wrote: post #19
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.…

Manufactured fuels have two main economies: one is energy input per energy output (usually bigger than one and the goal is to get that number as close to one as possible) and the other is transformer system cost, particularly cost that even applies when idle. If this number is very high fuel manufacturing won't be opportunistic at all and will keep the conversion systems at high utilization, offering input energy pri…

With the advent of cheap aerogels, LH2 is much easier to store than it once was.

Re: ZEROe: Hydrogen-hybrid aircraft concept

#49

Post by ncmncm »

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.

Re: ZEROe: Hydrogen-hybrid aircraft concept

#50

Post by ncmncm »

Robotbeat wrote: post #30
skykooler wrote: post #23

Earlier quoted context omitted.

Keep in mind however that all hydrocarbon fuels, kerosene included, turn into both CO2 and water.

In some ways, direct CO2 capture combined with carbon monoxide fuel (if burned super cleanly) might actually be better than either kerosene or hydrogen for super high altitude flight. The years-long lifetime of air in the stratosphere is small compared to the normal lifetime of CO2 in the atmosphere, so on net would be much better than hydrogen fuel.

How do you imagine capturing the CO2 coming out of a turbojet?
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