http://www.suttonfruit.com/pics/urea_electrolysis.pdf is the document on splitting urine.
They are showing the cost of hydrogen made this way as costing a little more then half of that made from splitting water in a fuel cell, the tough part of course is that the energy required to produce the hydrogen is still there, I'll have to look for my figures from a while back but I remember if you produced hydrogen from $.12 kwh electricity that energy wise it would be like paying $37 per gallon for gasoline, lets say this cuts it in half in an ideal world, that is still expensive energy, splitting urine is not free.