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The physics of hydrogen powered vehicles just don't make sense. Insane tank sizes at extremely high pressures are needed to get into practical range territory [

by jupp0r 5y ago

The physics of hydrogen powered vehicles just don't make sense. Insane tank sizes at extremely high pressures are needed to get into practical range territory [1]. This is fundamental physics and won't improve over time, as opposed to battery energy density and charging speeds. [1] https://www.youtube.com/watch?v=1Ajq46qHp0c https://www.youtube.com/watch?v=1Ajq46qHp0c

hnburnsy 5y ago
Did you see 9000 pound Hummer EV with 3000 pounds of battery? Wonder what would be the weight of a hydrogen powered equivalent would be.
- jupp0r 5y ago
  What's the problem with that weight? Road damage?
freeone3000 5y ago
Large size, yes, but low weight. Americans seem absolutely thrilled to drive around giant cars, so why not give them what they want?
- jupp0r 5y ago
  Aerodynamics, usable cargo space, road width, existing parking infrastructure, safety in case of an accident, terrorism, ...
- smileysteve 5y ago
  Compressed Hydrogen in even composite tanks is not particularly low weight.
semi-extrinsic 5y ago
What do you mean? You can just go and buy a Toyota Mirai today, and you could in 2016. The hydrogen tank is 27 gallons in volume and weighs 193 lbs, for a range of 312 miles. How big is a Model 3 battery pack again?
- CarVac 5y ago
  And yet the Model 3 weighs less than the Mirai.
- jupp0r 5y ago
  I mean that your back seat passengers are sitting[1] on a giant tank of highly explosive (when combined with oxygen) gas at 10000(!!!) psi when full. [1] https://en.wikipedia.org/wiki/Toyota_Mirai#/media/File:Toyota_Mirai_hydrogen_tank_and_electric_battery_SAO_2016_9030.jpg https://en.wikipedia.org/wiki/Toyota_Mirai#/media/File:Toyot...
  - semi-extrinsic 5y ago
    Your first comment was referring to "insane tank sizes". I still don't see what is insane? You can of course fearmonger on any topic: in any gasoline car on the market today, your back seat passengers are sitting on a huge quantity of highly flammable liquid! And it is stored in just a regular plastic container! In fact, the Mirai only has 600 MJ of energy stored in its fuel tank, while a gasoline car has around 2200 MJ! And a gasoline leak will pool around the car, while a hydrogen leak will go safely away up into the air due to buoyancy! Yet nobody bats an eye at the gasoline car. We engineer our cars such that fuel tank rupture is extremely unlikely in even severe accidents, with redundant safety systems all around.
    - jupp0r 5y ago
      I don’t think you appreciate the mechanical energy stored in these tanks. The chemical energy is not the problem as you pointed out. Do you know a tire rupture can kill somebody at short distance? Well these tanks are using 200 times more pressure and multiple times the volume (stored mechanical energy increases linearly with both pressure and volume).
ialyos 5y ago
Did you watch the video you linked?
- jupp0r 5y ago
  Sorry I actually wanted to link to this one from the same channel, thanks for noticing. https://www.youtube.com/watch?v=3IPR50-soNA https://www.youtube.com/watch?v=3IPR50-soNA
paulmd 5y ago
you can't keep increasing battery capacity indefinitely either, batteries become more reactive as the electrode potential increases, so there's physical limits to what batteries can (safely) deliver too. Unfortunately a lot of the battery capacity gains of the last 15 years have resulted from loosening these tolerances for fire/explosion, I'm thinking about lithium-ion and lithium-polymer chemistry here. Lithium-iron-phosphate is an example of a safer chemistry, but it also has significantly lower energy density, it's probably still better than NiMH but not anywhere near as much as lithium-ion or polymer types. That means that if you are looking at an iso-safety sense, the gains have been much slower than "maximum potential even if you are ok with batteries exploding when overcharged/overloaded/punctured". We have just been ramping up our tolerance for batteries of the latter type.
- jupp0r 5y ago
  There is lots of potential in terms of safety and density in solid state batteries [1]. [1] https://en.wikipedia.org/wiki/Solid-state_battery https://en.wikipedia.org/wiki/Solid-state_battery

by jupp0r 5y ago

hnburnsy 5y ago

Did you see 9000 pound Hummer EV with 3000 pounds of battery? Wonder what would be the weight of a hydrogen powered equivalent would be.

jupp0r 5y ago
What's the problem with that weight? Road damage?

freeone3000 5y ago

Large size, yes, but low weight. Americans seem absolutely thrilled to drive around giant cars, so why not give them what they want?

jupp0r 5y ago
Aerodynamics, usable cargo space, road width, existing parking infrastructure, safety in case of an accident, terrorism, ...
smileysteve 5y ago
Compressed Hydrogen in even composite tanks is not particularly low weight.

semi-extrinsic 5y ago

What do you mean? You can just go and buy a Toyota Mirai today, and you could in 2016. The hydrogen tank is 27 gallons in volume and weighs 193 lbs, for a range of 312 miles. How big is a Model 3 battery pack again?

CarVac 5y ago
And yet the Model 3 weighs less than the Mirai.
jupp0r 5y ago
I mean that your back seat passengers are sitting[1] on a giant tank of highly explosive (when combined with oxygen) gas at 10000(!!!) psi when full. [1] https://en.wikipedia.org/wiki/Toyota_Mirai#/media/File:Toyota_Mirai_hydrogen_tank_and_electric_battery_SAO_2016_9030.jpg https://en.wikipedia.org/wiki/Toyota_Mirai#/media/File:Toyot...
- semi-extrinsic 5y ago
  Your first comment was referring to "insane tank sizes". I still don't see what is insane? You can of course fearmonger on any topic: in any gasoline car on the market today, your back seat passengers are sitting on a huge quantity of highly flammable liquid! And it is stored in just a regular plastic container! In fact, the Mirai only has 600 MJ of energy stored in its fuel tank, while a gasoline car has around 2200 MJ! And a gasoline leak will pool around the car, while a hydrogen leak will go safely away up into the air due to buoyancy! Yet nobody bats an eye at the gasoline car. We engineer our cars such that fuel tank rupture is extremely unlikely in even severe accidents, with redundant safety systems all around.
  - jupp0r 5y ago
    I don’t think you appreciate the mechanical energy stored in these tanks. The chemical energy is not the problem as you pointed out. Do you know a tire rupture can kill somebody at short distance? Well these tanks are using 200 times more pressure and multiple times the volume (stored mechanical energy increases linearly with both pressure and volume).

ialyos 5y ago

Did you watch the video you linked?

jupp0r 5y ago
Sorry I actually wanted to link to this one from the same channel, thanks for noticing. https://www.youtube.com/watch?v=3IPR50-soNA https://www.youtube.com/watch?v=3IPR50-soNA

paulmd 5y ago

you can't keep increasing battery capacity indefinitely either, batteries become more reactive as the electrode potential increases, so there's physical limits to what batteries can (safely) deliver too. Unfortunately a lot of the battery capacity gains of the last 15 years have resulted from loosening these tolerances for fire/explosion, I'm thinking about lithium-ion and lithium-polymer chemistry here. Lithium-iron-phosphate is an example of a safer chemistry, but it also has significantly lower energy density, it's probably still better than NiMH but not anywhere near as much as lithium-ion or polymer types. That means that if you are looking at an iso-safety sense, the gains have been much slower than "maximum potential even if you are ok with batteries exploding when overcharged/overloaded/punctured". We have just been ramping up our tolerance for batteries of the latter type.

jupp0r 5y ago
There is lots of potential in terms of safety and density in solid state batteries [1]. [1] https://en.wikipedia.org/wiki/Solid-state_battery https://en.wikipedia.org/wiki/Solid-state_battery