I'm not the least bit sold on fuel cells. In operation they sure are gret, but the main source for hydrogen in the world today is water. It takes an INCREDIBLE amount of electricity (from burning coal) to break water down. On top of that you're left with free oxygen molecules which might sound great from those of us who need it to live, but does anyone have any idea what a massive, constant release of it would do to our atmosphere? I sure don't.
Interestingly enough, global warming is not a new issue, but has become a greater issue in the last 20 years not due to pollution, but from a LACK of pollution. Those same smokestacks that belched out acid rain causing sulfur rich smoke also had the benefit of putting particulate matter in the air that reflected a tremendous amount of solar radiation back into space. In fact, there is some debate in the scientific world about how effective it might be to release particles of reflective material into the upper atmosphere to gain the same affect. The problem with that idea is that....well....there will be particles in the air.
I am yet to meet an engineer working on fuel cell technology that feels that they are nearly as promising as the rest of the world seems to think they are. Nuclear power touted many of the same benefits 60 years ago that fuel cells are today. Cheap, clean, efficient power. Look at how far that has taken us.
I hate to sound like such a pessimist, but I really think there are better avenues we could go down in trying to find a solution to this global warming problem.