Quote:
Originally Posted by ConnClark
All the big car companies that are experimenting with hydrogen vehicles use metal hydride hydrogen tanks. The reason is it prevents the hydrogen from being released quickly in case of a storage tank breach. This provides time for it to disperse or burn off slowly.
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They actually use them because its easier. Its what the aircraft companies have been doing for years with oxygen. The reason is the hydride is MUCH lighter than any tank. Even if we ignore safety completely the pressurized cylinder that would be needed to hold that much H2 would weight a ton.
Scuba tanks rated up to a few thousand PSI only hold 60-100 ft^3 of air(not very much fuel) and they weigh in around from 25-50 lbs dry. Multiply that by 10 times or so to get a decent amount of fuel and you weigh four times more than my gas tank. OR as much as my gas tank and engine for just the fuel.
H2 does have a very high dispersive rate. Its collisions are much more elastic than as I mentioned methane or propane. a LEAK would be very dangerous yes because it would be a much more controlled pressure release than the tank being ruptured. I've been in the shop when H2 tanks and O2 tanks are dropped and its pretty nerve racking to see it coming.
Whenever high-pressured vessels rupture from a high energy impact(car collision, bullets, dropping a substantially heavy enough object on them) the pressure can force massive crack propogation. If and when they break they go in in a big way. Leaks usually occur at the valves or seems and are caused by fatigue.
Seriously try to light a stream of H2 coming out something the size of a welding torch from 3 inches away from the nozzle. Not happening. Oxyacetlyne Will do it just fine, propane and methane will do it to. Its why they use hydrogen in High Energy heat engines because it very quickly converts energy to movement(pressure).