How can you ? Arent we talking about 10000 psi tanks of H2 ?? Hydrogen gas has a huge explosive range. I wouldnt want to be caught in a rear end in one of those!
yes, if it's confined- if the tank ruptures, and the gas escapes but is not confined, it would be displaced by the heavier atmospheric gasses, and rise, unlike gasoline, which can pool on the ground. 'course if the accident occurs in an underground parking garage, you might have a problem...
One concern might be, however, a relatively small leak that ignites, creating a jet of flame that couldn't be seen in daylight..
No, usually a full lab/industrial cylinder of H2 only runs about 2500 psi. Portable bottles would run much lower pressures, especially if they were well-insulated cryogenic (liquid hydrogen) storage.
The danger inherent in hydrogen is much less than that of gasoline. Hydrogen, being a gas and lighter than air, will rise away from a leak, and dissipate into the atmosphere. Gasoline, on the other hand, pools and collects and concentrates, from leaks. Hydrogen's flame has a low emissivity compared to gasoline flames, meaning that one can get much closer to a hydrogen flame and not suffer any heat injury than one could get to a gasoline fire.
Hydrogen is already in wide use, daily, around the world in industrial settings. It's a material to be respected, surely, but procedures for safe handling of hydrogen have long been established and are well-tested.
And the Hindenburg? Two-thirds of the people aboard walked away.
Dude, he works for a fuel cell company. Fuel cells typical store hydrogen in a solid matrix. No high pressure, no large volumes of hydrogen and oxygen being mixed.
The downsides to fuel cells right now is longevity, reusability and operation efficiency, not combustability.