The Oil Drum

77 comments on EROEI Short #1: Boundaries & Calculations

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jeffvail on August 23, 2007 - 12:25pm

For simplicity I will assume that all forms of energy are economically equivalent. Without this assumption simple energy balance calculations do not work, and one must inject energy quality factors into the analysis.

I agree that your proposed metric is valuable in some analysis... my concern is with the nature of the assumptions that tend to be made when considering energy issues. The boundary drawing issue discussed above is the crux of many assumption-problems.

A little parable:

An engineer, a physicist, and an economist are stuck on a desert island with only a can of beans to sustain them. The engineer considers finding a rock to break open the can. The physicist suggests placing it in the sun so that it heats up and bursts. The economist says "first, assume we have a can opener..."

That said, economists often get a bad reputation in this regard, as they tend to be less careful to hide their most fundamental assumptions...

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Roger K on August 23, 2007 - 2:15pm

Jeff,

I agree that the assumption that all forms of energy are economically equivalent is clearly false, although this issue is different that the boundary problem you discuss above. Real world calculations of energy quality would have to account for variations in the economic usefulness of differnt forms of energy as well as for energy embedded in production resources.

To tell you the truth, I am not overly enamored of net energy analysis. Consider the tremendous amount of acrimonious debate that has taken place over the energy balance of corn ethanol. All one has to do is look at the gross output per hectare and it is clear that this fuel source is an economic loser. In addition row cropping of corn leads to a topsoil loss rate greater than the replacement rate, so that this form of farming is inherently unsustainable. Independent of how much net energy is provided this form of agriculture should be brought to an end.

I developed these metrics not so much for practical calculations, but rather to provide my self with a conceptual tool for thinking about energy quality. I am doubtful that net energy calculation will play much role in determining the amount of fuel that will be extracted from the Canadian tar sands after they run out of stranded natural gas or of determining how much fuel will be extracted from American oil shale deposits. Practical engineering and cost calculations (and possible political consideration related to CO2 emissions) will rule the day.