3 ms·

Why not also in cars and trucks, then?

giantg2 5y ago
It sounds like this requires cryogenic cooling equipment. That might mean there are strict fueling and defueling procedures that are more applicable to the already highly procedure-ized flight industry. Also, if that tank ruptured during a crash, then it would be catastrophic. Crashes happen much less frequently in commercial aviation vs on the roadways. Hydride tanks would be a much safer option for roads. However they weigh more with less storage and would not be suitable for most aircraft. Plus, it seems that due to international nuclear weapons treaties, one of the components of the hydride tanks is difficult to source.
- Zigurd 5y ago
  The danger from fuel tanks rupturing is hard to intuit. Hydrogen will gasify and escape upward. But the hydrogen tanks themselves could fragment and be propelled by the pressure in the tanks. It is an open question whether this is worse than kerosine escaping fuel tanks and pooling around a crashed plane.
  - someguydave 5y ago
    at least kerosene burns with a visible flame…
    - rbanffy 5y ago
      Noise is just one of the many reasons you were not allowed less than a couple kilometres from a shuttle launch.
    - giantg2 5y ago
      Sort of a moot comparison, right? We can see a flame from kerosene, but kerosene burns slowly. We can't see a flame for hydrogen, but it is gaseous and burns so fast that it essentially detonates. Given that small timescale, that means we wouldn't be able to act on that information (seeing a flame) anyways.
      - jandrese 5y ago
        "You will be dead before you could see the flame anyway" isn't exactly a point in its favor.
        giantg2 5y ago
        It's showing that the other person's detracting point about not seeing a flame is moot.
      - someguydave 5y ago
        hydrogen fires burning over a long period have definitely happened https://h2tools.org/lessons/liquid-hydrogen-delivery-truck-offloading-valve-failure https://h2tools.org/lessons/liquid-hydrogen-delivery-truck-o...
  - giantg2 5y ago
    Considering the ignition temperature of kerosene is much higher, the deflagrenation of kerosene is much lower, and that the hydrogen will expand in the immediate area before/as it escapes up, I don't think there's too much of an open question. They are both bad scenarios, and the impact required to rupture suffienctly protected fuel containers on newer planes means its unlikely that the after effects playing of a role on the safety. My reply was focused why we wouldn't use this for cars and trucks. While fuel containers tend to be well protected on newer vehicles, the number of accidents on the roads still sees some ruptures/fires. The hydride tanks tend to be a better option since they will just smolder as the gas escapes slowly, compared to liquid hydrogen tanks which practically detonate either from the rapid release of the pressure or from the rapid deflagrenation (which occurs at a much lower flashpoint than gasoline).
- LargoLasskhyfv 5y ago
  New safety system idea: In case of impeding crash use the hydrogen to inflate a large balloon made of ultra-thin space age mylar and touch down ever so softly by dangling from that :-)
protomyth 5y ago
If I remember correctly, AirBus was going with a plan to replace the the whole tank on the aircraft and refuel the tanks offsite. Think of pulling up to a gas station and an attendant taking your gas tank and replacing with a full one while sending tanks down the road to refuel. Could work, but would be a major infrastructure change. The main thing is batteries are too heavy (cars and trucks shouldn't fly) and this is the best solution of a lot of less dense energy choices.
LadyCailin 5y ago
Weight isn’t the largest factor for terrestrial based transportation. Other factors, such as total energy cost per km, fuel production and distribution, and user serviceability are far more important. Commercial trucking and perhaps even fleets of cars such as taxis might be interested, but it’s already been shown that electric is winning out for regular passenger cars, since it tends to be superior in almost all the points outlined above. Hydrogen really only works if you have some single issue that it solves which is by far the most important factor in your niche.

It sounds like this requires cryogenic cooling equipment. That might mean there are strict fueling and defueling procedures that are more applicable to the already highly procedure-ized flight industry. Also, if that tank ruptured during a crash, then it would be catastrophic. Crashes happen much less frequently in commercial aviation vs on the roadways. Hydride tanks would be a much safer option for roads. However they weigh more with less storage and would not be suitable for most aircraft. Plus, it seems that due to international nuclear weapons treaties, one of the components of the hydride tanks is difficult to source.

Zigurd 5y ago
The danger from fuel tanks rupturing is hard to intuit. Hydrogen will gasify and escape upward. But the hydrogen tanks themselves could fragment and be propelled by the pressure in the tanks. It is an open question whether this is worse than kerosine escaping fuel tanks and pooling around a crashed plane.
- someguydave 5y ago
  at least kerosene burns with a visible flame…
  - rbanffy 5y ago
    Noise is just one of the many reasons you were not allowed less than a couple kilometres from a shuttle launch.
  - giantg2 5y ago
    Sort of a moot comparison, right? We can see a flame from kerosene, but kerosene burns slowly. We can't see a flame for hydrogen, but it is gaseous and burns so fast that it essentially detonates. Given that small timescale, that means we wouldn't be able to act on that information (seeing a flame) anyways.
    - jandrese 5y ago
      "You will be dead before you could see the flame anyway" isn't exactly a point in its favor.
      - giantg2 5y ago
        It's showing that the other person's detracting point about not seeing a flame is moot.
    - someguydave 5y ago
      hydrogen fires burning over a long period have definitely happened https://h2tools.org/lessons/liquid-hydrogen-delivery-truck-offloading-valve-failure https://h2tools.org/lessons/liquid-hydrogen-delivery-truck-o...
- giantg2 5y ago
  Considering the ignition temperature of kerosene is much higher, the deflagrenation of kerosene is much lower, and that the hydrogen will expand in the immediate area before/as it escapes up, I don't think there's too much of an open question. They are both bad scenarios, and the impact required to rupture suffienctly protected fuel containers on newer planes means its unlikely that the after effects playing of a role on the safety. My reply was focused why we wouldn't use this for cars and trucks. While fuel containers tend to be well protected on newer vehicles, the number of accidents on the roads still sees some ruptures/fires. The hydride tanks tend to be a better option since they will just smolder as the gas escapes slowly, compared to liquid hydrogen tanks which practically detonate either from the rapid release of the pressure or from the rapid deflagrenation (which occurs at a much lower flashpoint than gasoline).
LargoLasskhyfv 5y ago
New safety system idea: In case of impeding crash use the hydrogen to inflate a large balloon made of ultra-thin space age mylar and touch down ever so softly by dangling from that :-)

protomyth 5y ago

If I remember correctly, AirBus was going with a plan to replace the the whole tank on the aircraft and refuel the tanks offsite. Think of pulling up to a gas station and an attendant taking your gas tank and replacing with a full one while sending tanks down the road to refuel. Could work, but would be a major infrastructure change. The main thing is batteries are too heavy (cars and trucks shouldn't fly) and this is the best solution of a lot of less dense energy choices.

LadyCailin 5y ago

Weight isn’t the largest factor for terrestrial based transportation. Other factors, such as total energy cost per km, fuel production and distribution, and user serviceability are far more important. Commercial trucking and perhaps even fleets of cars such as taxis might be interested, but it’s already been shown that electric is winning out for regular passenger cars, since it tends to be superior in almost all the points outlined above. Hydrogen really only works if you have some single issue that it solves which is by far the most important factor in your niche.