How dangerous is it to store compressed hydrogen gas in a passenger vehicle?
Short answer: hydrogen is dangerous…almost as dangerous as gasoline, propane and natural gas! Long answer: compressed hydrogen tanks are extraordinarily strong. They have to be strong to hold pressures between 37 MPa and 70 MPa (350 to 700 bar or 5,000 to 10,000 psi) These high pressure tanks have been shown to survive simulated rear end collisions at speeds up to 52 mph without leaking. Obviously no gasoline tank could survive such an impact. Gasoline and propane pose serious risk since their vapors are heavier than air. Gasoline fumes released in any collision linger beneath the vehicle and are sometimes ignited while people are still alive but trapped inside the wreckage (see section on hydrogen safety). Automobile fires kill an average of 490 people per year in the US, with gasoline responsible for more than half of fatal fires after collisions. Hydrogen is less dangerous in a collision, since hydrogen is much lighter than air. Any hydrogen released will rise and disperse quickly
