4 ms·

> 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 is

> 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?

JAlexoid 6y ago
Hydrogen leaking is an issue for longer term storage, not particularly an issue for liquid hydrogen that is going to run an airplane for a very specific number of hours.
- liability 6y ago
  > 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..
  - JAlexoid 6y ago
    I never addressed the lifespan of containers, that's not same as hydrogen leakage.
    - rbanffy 6y ago
      Still embrittlement is an issue. How long until the hydrogen tank needs replacement? Liquid per liquid, why not liquid methane that's far easier to work with and can be manufactured at zero carbon emissions.
    - liability 6y ago
      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.
m4rtink 6y ago
Not to mention hydrogen fires being invisible to unaided eye in daylight.
- ncmncm 6y ago
  Hydrogen at atmospheric pressure is hard to ignite in uncontrolled circumstances. It wants a specific gas/air ratio.
  - usrusr 6y ago
    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.
    - ncmncm 6y ago
      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.
  - m4rtink 6y ago
    Might be space flight specific (ideal ratios/big flows of hydrogen maybe ?) but NASA seems to take hydfrogen fires very seriously: https://spinoff.nasa.gov/spinoff1997/ps1.html https://spinoff.nasa.gov/spinoff1997/ps1.html

JAlexoid 6y ago

Hydrogen leaking is an issue for longer term storage, not particularly an issue for liquid hydrogen that is going to run an airplane for a very specific number of hours.

liability 6y ago
> 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..
- JAlexoid 6y ago
  I never addressed the lifespan of containers, that's not same as hydrogen leakage.
  - rbanffy 6y ago
    Still embrittlement is an issue. How long until the hydrogen tank needs replacement? Liquid per liquid, why not liquid methane that's far easier to work with and can be manufactured at zero carbon emissions.
  - liability 6y ago
    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.

m4rtink 6y ago

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

ncmncm 6y ago
Hydrogen at atmospheric pressure is hard to ignite in uncontrolled circumstances. It wants a specific gas/air ratio.
- usrusr 6y ago
  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.
  - ncmncm 6y ago
    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.
- m4rtink 6y ago
  Might be space flight specific (ideal ratios/big flows of hydrogen maybe ?) but NASA seems to take hydfrogen fires very seriously: https://spinoff.nasa.gov/spinoff1997/ps1.html https://spinoff.nasa.gov/spinoff1997/ps1.html