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You are betting on a 20x improvement in mass energy density of batteries for that to become realistic. That would probably require entirely new chemistries and

You are betting on a 20x improvement in mass energy density of batteries for that to become realistic. That would probably require entirely new chemistries and while I am not going to rule it out, there is really no good reason to believe that it will happen either. Hydrogen powered flight is on the other hand only a matter of incremental improvements. It is already feasible today.

_aavaa_ 3y ago
Damn straight I am: https://www.energy.gov/eere/vehicles/articles/fotw-1234-april-18-2022-volumetric-energy-density-lithium-ion-batteries https://www.energy.gov/eere/vehicles/articles/fotw-1234-apri... Ain’t no incremental improvement going to improve the density of a gas or a liquid. On top of that you talk of energy per mass, but what kills you for flights is also volume. Hydrogen power flights are not feasible today. Even hydrogen busses are struggling to operate, to say. I thing of trains. For starters you’ll need hydrogen at any and all possible destinations (plus any nearby airports if you’re diverted) since nobody is going to buy a plane that will likely get stranded. Then: 1. Hydrogen’s energy/volume is far too low. 2. You can’t store it in the empty space in the fuselage due to pressure vessel geometry requirements. 3. You need heaters and coolers and all sorts of extra parts to operate something hydrogen power (hint: a hydrogen car is just an electric car with a small battery and a while separate hydrogen system frankesteined ontop). 4. Going back to that volume, you’ll need to store the hydeogren tanks inside the main fuselage, where the volume required is going to either eat into your available volume for cabin or cargo. OR, you’re gonna need a bigger cross-section, which will increase your drag. To top all that off. Nobody is using green hydrogen. They’re using hydrogen made directly from methane (or god help us coal). This hydrogen has more GhG emissions associate with it than the methane it’s made from. Hydrogen itself also has a GHG impact since it will interfere with the processes occurring that remove other GHGs.
- goethes_kind 3y ago
  The bottom line is, the batteries that you would need do not exist yet. You just have faith that your extrapolation holds true. I cannot comment on that either way, because there is no way to tell when battery energy densities will stop improving. Synthetic kerosene is a technology that we have today and imho the most likely option because it is plug and play. Otherwise one would have to work out many modifications to fly directly on hydrogen, but that is also technically possible today, if one wanted to do it that way.
  - _aavaa_ 3y ago
    There is no way to know when it stops, but looking at the historical trend it isn’t slowly down yet. The technology for synthetic karosene is something we have today, expect it cost more 10x regular karosene and: A) what’s the path to scale to bring that number down? Who isn’t going to pay that 10x price while it’s that high. Batteries had cell phones, then laptop, then cars and storage. Now it’s trucks, ships and planes are next up. B) by continuing with combustions engines you keep the same operating costs that you have now. Whereas electrification gets rid of many of them (same way it did for cars).
- _hypx 3y ago
  > Damn straight I am: https://www.energy.gov/eere/vehicles/articles/fotw-1234-april-18-2022-volumetric-energy-density-lithium-ion-batteries https://www.energy.gov/eere/vehicles/articles/fotw-1234-apri... Seriously, that claim is just bullshit. 55 Wh/L is worse than a lead-acid battery. That graph is straight-up lying.
  - _aavaa_ 3y ago
    That number is for the battery pack as a whole, not just the lithium ion cell.
    - _hypx 3y ago
      And how did they fail so badly as to get a li-ion battery pack with worse energy density than lead-acid batteries? I'm sorry, but that is simply far too ridiculous to be taken seriously. It's blatantly some made-up number that no one can believe.
theshrike79 3y ago
The biggest advantage of electric flight is the maintenance interval. Electric engines need next to no maintenance. Jet engines need to be maintained pretty much after every flight and that costs $$.

_aavaa_ 3y ago

Damn straight I am: https://www.energy.gov/eere/vehicles/articles/fotw-1234-april-18-2022-volumetric-energy-density-lithium-ion-batteries https://www.energy.gov/eere/vehicles/articles/fotw-1234-apri... Ain’t no incremental improvement going to improve the density of a gas or a liquid. On top of that you talk of energy per mass, but what kills you for flights is also volume. Hydrogen power flights are not feasible today. Even hydrogen busses are struggling to operate, to say. I thing of trains. For starters you’ll need hydrogen at any and all possible destinations (plus any nearby airports if you’re diverted) since nobody is going to buy a plane that will likely get stranded. Then: 1. Hydrogen’s energy/volume is far too low. 2. You can’t store it in the empty space in the fuselage due to pressure vessel geometry requirements. 3. You need heaters and coolers and all sorts of extra parts to operate something hydrogen power (hint: a hydrogen car is just an electric car with a small battery and a while separate hydrogen system frankesteined ontop). 4. Going back to that volume, you’ll need to store the hydeogren tanks inside the main fuselage, where the volume required is going to either eat into your available volume for cabin or cargo. OR, you’re gonna need a bigger cross-section, which will increase your drag. To top all that off. Nobody is using green hydrogen. They’re using hydrogen made directly from methane (or god help us coal). This hydrogen has more GhG emissions associate with it than the methane it’s made from. Hydrogen itself also has a GHG impact since it will interfere with the processes occurring that remove other GHGs.

goethes_kind 3y ago
The bottom line is, the batteries that you would need do not exist yet. You just have faith that your extrapolation holds true. I cannot comment on that either way, because there is no way to tell when battery energy densities will stop improving. Synthetic kerosene is a technology that we have today and imho the most likely option because it is plug and play. Otherwise one would have to work out many modifications to fly directly on hydrogen, but that is also technically possible today, if one wanted to do it that way.
- _aavaa_ 3y ago
  There is no way to know when it stops, but looking at the historical trend it isn’t slowly down yet. The technology for synthetic karosene is something we have today, expect it cost more 10x regular karosene and: A) what’s the path to scale to bring that number down? Who isn’t going to pay that 10x price while it’s that high. Batteries had cell phones, then laptop, then cars and storage. Now it’s trucks, ships and planes are next up. B) by continuing with combustions engines you keep the same operating costs that you have now. Whereas electrification gets rid of many of them (same way it did for cars).
_hypx 3y ago
> Damn straight I am: https://www.energy.gov/eere/vehicles/articles/fotw-1234-april-18-2022-volumetric-energy-density-lithium-ion-batteries https://www.energy.gov/eere/vehicles/articles/fotw-1234-apri... Seriously, that claim is just bullshit. 55 Wh/L is worse than a lead-acid battery. That graph is straight-up lying.
- _aavaa_ 3y ago
  That number is for the battery pack as a whole, not just the lithium ion cell.
  - _hypx 3y ago
    And how did they fail so badly as to get a li-ion battery pack with worse energy density than lead-acid batteries? I'm sorry, but that is simply far too ridiculous to be taken seriously. It's blatantly some made-up number that no one can believe.

theshrike79 3y ago

The biggest advantage of electric flight is the maintenance interval. Electric engines need next to no maintenance. Jet engines need to be maintained pretty much after every flight and that costs $$.