[stonemetal]

>According to the 2010 California Low Carbon Fuel Standard Final Regulation Order, fuel-cell cars have an average lifetime greenhouse gas emissions rate of 61.83 grams of carbon dioxide per megajoule. This is for hydrogen produced through the popular natural gas reforming process.

Electricity, on the other hand, was determined to have average lifetime greenhouse gas emissions of 41.37g/mj.

http://ecomento.com/guide/hydrogen-fuel-cell-vs-battery-elec...

Currently fuel cell backed EVs produce ~50% more greenhouse gas emissions than battery backed EVs. If you are going for green factor take the batteries.