Why are hydrogen-powered cars not available?
The Hindenburg. The technology to operate IC engines on hydrogen has been investigated in depth since before the turn of the century. One attraction was to use the hydrogen in airships to fuel the engines instead of venting it. Hydrogen has a very high flame speed ( 3.24 – 4.40 m/s ), wide flammability limits ( 4.0 – 75 vol% ), low ignition energy ( 0.017 mJ ), high autoignition temperature ( 520C ), and flame temperature of 2050 C. Hydrogen has a very high specific energy ( 120.0 MJ/kg ), making it very desirable as a transportation fuel. The problem has been to develop a storage system that will pass all safety concerns, and yet still be light enough for automotive use. Although hydrogen can be mixed with oxygen and combusted more efficiently, most proposals use air [73,77]. Unfortunately the flame temperature is sufficiently high to dissociate atmospheric nitrogen and form undesirable NOx emissions. The high flame speeds mean that ignition timing is at TDC, except when running lean,
