How much energy does it take to make (collect) the hydrogen? I am guessing unless you are moses splitting water isn't that easy?!
Unless you can supply enough power by solar or wind etc to do the hydrogen collection/bottling, then all you are doing is moving the source of the pollution ... I suppose if we can be 100% nuclear then its not as bad pollution wise ... but I betya that truly renewable sources are not practical with the amount of energy required?!?!
Its a bit like electric cars/bikes ... its just moving the source of the pollution .. and every time you convert energy you use a bit up ... i.e. essentially converting the energy twice is probably pretty inefficient way of doing things overall?!?! Saying that I guess boiling a tub of oil to get petrol must take a few calories too
... how comparable is it to that in making (extracting) the hydrogen?