Todd
I apologize if I came off as a smart-ass. I honestly didn't mean to. The question concerning calculation of energy consumed at the rubber plant you supervised was sincere. If it can be done there, why not on a broader scale? I was looking for insight, not challenging you.

As to the point you raised concerning "usefullness," I wasn't refering to usefullness in any economic sense. So I understand your irritation. I simply meant that if we're going to define EROEI, shouldn't parameters be set based on the nature of the question we're trying to answer. What do we mean when we ask the question,"Is the production of ethanol from sugar more energy efficient than from corn?" Are we asking about the energy used from the point that the sugar or corn begins to be processed or are we asking a broader question about the total energy efficiency of the systems providing trasportation, labor, distribution, etc. My point was that it would seem to make sense to start with the more restricted question and build outward. In other words, the EROEI for the process of converting ethanol from each feedstock is x from sugar and y from corn. Now, add into the ratio energy consumed for production of tractors used on ethanol farms in Brazil and corn farms in the U.S. and the EROEI becomes t from sugar and u from corn. In its narrow sense EROEI would be the most accurate and as the ratio is made more complex by adding layers of inputs it would lose precision but give us information about not just the processing of the fuel but possible comparative advantages in the sense of energy efficiency from one production center to another.

It just seems the debate, which from some of the comments I've read has tried the patience of alot of thinking people, revolves around trying to define the concept without having precisely defined the question.