Looks like things are closing in on having a hydrogen burning motor in the near future: hyrogen as fuel article.

 

I see several of problems right off the bat:
a) it will require 100% ethanol (water would react with calcium)
b) some/all carbon may end up as CO2
c) ethanol production by fermentation/distillation requires quite a bit of energy
d) it might just be more efficient to use the ethanol directly
I could probably think up more, but these four are more than enough for me to consider this method DOA.

Barring some major biological breakthrough, my opinion is that once natural gas gets more expensive, electrolysis will be the preferred method of generating hydrogen on demand.

 

its better to to release all co2, compared to co2 methane sulferdioxide and all that other crap....