While I agree that ethanol subsidies are crazy, I disagree that it’s as ‘simple as thermodynamics’ (I’m paraphrasing so that I don’t have to hit the ‘back’ button). The idea is not simply converting one substance into another to use the result as fuel. The idea is that corn (and other biomass) already contain a lot of energy because of photosynthesis. It’s really just a version of solar power. The energy put in is of course more than what comes out, but most of what went in was the sunlight, not the oil used to refine the ethanol.
We had a previous thread (Ethanol as Fuel) which started with a discussion of this very topic. Concensus was, of course, that no flouting of the second law is necessary, for exactly the reasons you outlined, and shame on Cecil for saying so, even in jest.
From there, the thread evolved (or devolved, depending on your perspective) into a more general discussion of the column and ethanol prodution, with some participants saying silly things, and some saying not-so-silly things, and cites and calculations being thrown around, and I think some jello-wrestling there at the end. An enjoyable experience all around.
One point not raised in the other thread, which I recently heard in the context of a political debate here: Supposedly, the major by-product of the corn kernal after ethanol production is still suitable for use as a high protein cattle feed. If this is true, then it would either raise the value of the output, or decrease the cost, depending on how you look at it, of growing corn for purposes of biomass ethanol. Is this enough to make biomass ethanol practical?
That point was raised in the other thread, albeit tangentially. renefast, who seems to know what he’s talking about, mentioned a “circular” ethanol facility (post 31) where the spent mash from the distilling process is fed to cows. He didn’t, however, say how much the reuse of the mass increased the overall cycle energy output.
A similar point was made in a report originally linked to by maverik, which I also reference (post 56, which includes a link). In that report, the authors assume that the waste products from the distillation pracess are used as fertilizer (not exactly cattle feed, but still an agricultural usage), but still don’t put a number to the energy savings associated with that usage.