"And even if we figured out how to process cellulose into ethanol efficiently, only one-third of our greenhouse gas emissions come from transportation."
2/3rds of CO2 comes from power plants of various types, 50% in electrical utilities, most of that from coal.
5899 million metric tons in 2005 total from all uses.
1900 million metric tons from transportation.
Electrical generation was 2245 million metric tons in 1999. 1787 million metric tons from coal.
By shifting electricity generation from coal / fossil fuel plants to nuclear power plants, we can reduce the US emissions by 50% and end the 'threat' of our CO2 emissions creating a serious concern.
By further leveraging nuclear-base electricity as an energy source for transportation (think plug-in hybrid), we can further reduce CO2 emissions by another 50%.
For CO2 generation numbers, see :
http://www.eia.doe.gov/oiaf/1605/gg98rpt/carbon.html
http://www.eia.doe.gov/emeu/aer/pdf/pages/sec12_5.pdf
Thanks for the links.