[jyl]

I have read a study that conclude that for corn-derived ethanol to make a meaningful dent in US oil imports would create shortages in corn used for food (food, feed, high-fructose corn syrup, corn oil, etc).

Since ethanol produced from corn is not that cheap relative to conventional oil, the effect could be simply to increase food prices while sending large tax subsidies to US agribusiness.

I'm sorry but I don't recall any of the numbers.

The issue could be with what crops are used. I recall that switchgrass was a more efficient crop. Somehow Brazil makes ethanol work, but I don't know what their economics are. Ultimately a part of the issue probably can be traced to the political power of the farming states. Considering that agriculture is barely 2% of the economy, in employment and GDP, we seem to spend a disproprotionate amount of tax dollars to subsidize it.