Gallons vs Barrels - Is Ethanol worth it?

I found myself stumbling over the numbers in the State of the Union address, specifically the President's targets for upping ethanol production. Robert Samuelson, writing at the Washington Postputs it back into a context I can understand:

Suppose we reach the administration's ultimate target of 60 billion gallons in 2030. That would offset less than half of the projected increase in annual oil use. Here's why. First, it's necessary to convert the 60 billion gallons into barrels. Because there are 42 gallons in a barrel, that means dividing by 42. Further: Ethanol has only about two-thirds of the energy value of an equal volume of gasoline. When you do all the arithmetic, 60 billion gallons of ethanol displace just under 1 billion barrels of gasoline. If that merely offsets increases in oil use, it won't cut existing import dependence or greenhouse gases.

The 60 billion-gallon goal -- and the 35 billion-gallon interim target -- are also probably unrealistic. When we rhapsodize about biofuels, we're talking mainly about old-fashioned alcohol (aka ethanol). Until now, most ethanol has been made from corn. If small amounts of toxic gasoline were not added, it could become corn whiskey. Ethanol receives heavy federal subsidies. Oil refiners that blend it with gasoline get a 51-cents-a-gallon tax credit. The subsidy causes them to buy more ethanol, increasing corn demand.

What do all those gallons add up to?

60 B gallons of ethanol = 1.4 B barrels
35 B gallons of ethanol = 0.8 B barrels
8.5 B gallons = 202 Million barrels (proposed conservation)

On an annual basis we currently use ~ 7 B barrels of oil. Using the lower figure for ethanol, we are talking ~12% of the entire US oil requirement, or just shy 40 days worth of oil consumption. If US demand rises as expected, the ethanol won't make much of a difference in the future.

We currently use ~ 20 Million barrels of oil a day. The proposed level of conservation amounts to ~ 10 days of consumption.

So overall, we are not talking about more than 2 months (at the most) worth of reduced oil consumption. It's going to take a lot more.

Robert Rapier posted an analysis of alternatives, including ethanol, at The Oil Drum. It is his assessment of the viability of the alternatives available, including:

1. Is the energy source sustainable?
2. What are the potential negative externalities of producing/using this energy source?
3. What is the EROEI?
4. Is it affordable?
5. Are there better alternatives?
6. Are there other special considerations?
7. In summary, are the advantages of the source large enough to justify any negative consequences?

His bottom line appears to be that we need multiple alternate sources of fuel, and not all alternatives are worth pursuing. Including ethanol. I agree with him.