Acetylene gas is stored in
Acetylene gas is stored in containers that use a carbon compound to absorb the gas. The tanks hold roughly the same amount of gas they would if the acetylene were just stuffed in there under low pressure (pressurized acetylene creates enough friction on its own to ignite itself). Acetone is used to activate the compound so it absorbs the acetylene at low pressures (2-3 lbs).
It's not unlikely that the same can't be done for hydrogen. In the mean time, tanks have been made that are extremely safe for use on a vehicle. Fuel cells are becoming cheaper and have halved their cost in only a few years with new ways of removing the most expensive materials (catalysts) in favor of cheaper, more accessible ones being found, which will further drop the cost.