I got into a conversation about alternative energies over the holidays with a friend of mine who has her PhD in something Agricultural Science related from Purdue, and when the conversation went to ethanol she informed me that apparently there's a much better alternative in butanol. According to the first link I've provided, Butanol is both a "cleaner" fuel source than ethanol and has a higher energy content (110,000 Btu per gallon for butanol vs. 84,000 Btu per gallon for ethanol, for reference gasoline is 115,000 Btu per gallon). It requires little to no modification of existing engines and can be shipped through existing fuel pipelines. Historically it's been considered less viable than ethanol because of relatively higher production cost.
About Butanol Energy
However a researcher from the midwest (Ohio I think) has patented a process by which it can be produced more cheaply than ethanol *without having to change existing gasoline infrastructure.*
Here's the researcher's company.
More Butanol Information [butanol.com]
From what my friend told me, the only thing preventing this right now is a lack of funding and public awareness. So please read it for yourself and spread the word.