Paper in Proceeding Nat Accd. of Sciences, March 2007 "To overcome the environmental challenges associated with coal and the land limitations with the bioenergy crop, we suggest an alternative pathway where neither coal nor biomass is treated as a sole source of energy to produce liquid hydrocarbon fuel. In our proposal, the primary purpose of either coal or biomass is to provide carbon atoms needed for the production of liquid hydrocarbons. Thus, the goal is to accomplish the complete transformation of every carbon atom contained in either of the feed stocks to liquid fuel by supplementing the conversion process with a carbon-free energy source. We propose to generate H2 from a carbon-free primary energy source such as solar, nuclear, wind, etc. and then use it to supply the hydrogen atoms needed for the chemical transformation." "It should be emphasized that the proposed ‘‘sun to wheels’’ solution is successful in providing a viable sustainable route to meet the hydrocarbon fuel need for the total United States transportation sector." Full article at: http://www.purdue.edu/dp/energy/pdf/Agrawal-PNAS-Mar2007.pdf A hard read - lots of chemistry - but worth it.