Transportation and storage of hydrogen is a problem too. Most metals become brittle when they're exposed to hydrogen. This is one of the big hinderances to usin

Transportation and storage of hydrogen is a problem too. Most metals become brittle when they're exposed to hydrogen. This is one of the big hinderances to using hydrogen as a fuel. http://en.wikipedia.org/wiki/Hydrogen_embrittlement http://en.wikipedia.org/wiki/Hydrogen_embrittlement