The Oil Drum

It seems to me that the simplest (i.e. ignoring infrastrcture cost, water use, soil damage, etc) relevant metric from a peak oil perspective is the ratio of fossil fuel inputs to useable energy outputs.

Thus:
gasoline: 1 BTU (petroleum) input -> 0.8 BTU output
ethanol: 1 BTU (mix hydrocarbon) input -> 1.3 BTU output

In this context, inputs are just inputs; they may be, but are not necessarily, consumed.  It seems inappropriate to ignore the "input" of oil that becomes gasoline, just because it isn't literally consumed (i.e. burned) in the process.  You still have to put it in the front end, in order to get product out the back end.

Calculated this way, ethanol does beat gasoline.  Fine, so be it.  But it's a very simplified metric, and the net benefit, while positive, is small.

I think that this entire arguement is really a distraction from the bigger question of appropriate energy policy.  The detractors of corn ethanol are wasting their time splitting hairs over the definition of efficiency or EROIE, at least in the context of public debate.  The points that need to be made, loudly and clearly to the public, are these:

1. If you're concerned about peak oil, ethanol is no solution.  It's positive, but it's not positive enough to offset rising demand coupled with declines in production.

2. If you're not concerned with peak oil, but just want to reduce oil use (e.g. for national security reasons), then ethanol is still a waste of time.  The externalities are very high, and the return on investment is low compared to energy efficiency measures.

The pro-ethanol lobby has completely bollixed those who are interested in actual sane, sustainable energy policy by focusing excessive attention on the energy return question.  And the ethanol detractors have, for the most part, fallen for it.  We need to stop dancing to their tune, and talking from their frame.  Instead, accept their arguements as being "close enough" to correct, and demonstrate why those arguements are not sufficient to support a national move towards ethanol.

Disclaimer: all the above statements are specifically about corn ethanol.  Sugarcane ethanol is a different story, and cellulotic ethanol is a largely unknown story (and is therefor not a proper basis for making energy policy, IMO).