77 comments on EROEI Short #1: Boundaries & Calculations
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Roger,
It seems to me that you are trying to side-step the nitty-gritty issues. Clearly, energy went into the construction of the farmer's tractor and implements. It is also likely that fertilizers and peticides were used. The crops may have also been irrigated requiring an energy source, pumps and pipes. If biodiesel is being made, there are the tanks, heaters and chemicals. Then there is the issue of transporting the finished product to market.
All of these added inputs need energy for their construction and delivery to the farmer so where do you draw the line? Do you go back as far as the energy to make the equipment for the iron ore mine or what? This is the question.
I would argue that the list of energy inputs should go to the limit in order to have a complete picture. I realize that this sort of data gathering is almost impossible. But, most of it would only have to be done once. Further, I would discount those inputs of, say, less that 0.1% of the overall energy required in claculating the EROEI.
I used to run a synthetic rubber plant that, itself, has a bazillion energy inputs and that's just part of the overall energy picture. But it is possible to determine how much energy it took to make the synthetic rubber polymer and process it so I'd leave it go at that.
The other problem I see is the sort of conflating economics and energy. But I don't want to get into that.
Todd
Todd,
I was not trying to present a realistic calculation of energy balance. I was trying to conceptually illustrate the proper method of accounting for energy balance in determining the economic quality of energy. In a real world energy calculation of course embedded energy must be accounted for. Indirectly it counts as a fuel purchase such as I discussed above.
Your claim that I conflating energy and economics puzzles me. The underlying ideas expressed in my post are quite simple, though possibly I did not express them as clearly as I could. Energy provides services. Suppose you buy a tankful of gas and use it to travel 300 miles. The economic quality of that tankful depends on the amount of economic effort that was required to extract the oil, refine it, and transport it to the gas station. If for example it took 10 labor hours to produce a tankful of gas from conventional oil compared to 30 labor hours to produce a tankful of gas from oil shale, then clearly the gas produced from conventional oil is superior. This is common sense, not left field philosophical theorizing. The ideas expressed in my post are not any more complicated than this. Energy balance calculations just account for the excess resource costs due to the consumption energy during the production of fuel.
Roger,
Thx for responding. Ok, quoting you, "The economic quality of that tankful depends on the amount of economic effort that was required to extract the oil,...". Emphasis added. Economics has nothing to do with EROEI.
And, "If for example it took 10 labor hours to produce a tankful of gas from conventional oil compared to 30 labor hours to produce a tankful of gas from oil shale, then clearly the gas produced from conventional oil is superior." It may be superior (and, no, differential labor hours is not common sense) but that isn't what EROEI is about. It is how much energy is required to produce so many joules compared to how many joules you had to expend to get them. And, BTW, I've done energy balances for chemical plants so I am not unaware of how to do them.
Let's look at on-shore and ultra-deep water drilling. It may take more "labor hours" drilling on-shore but the infrastructure for deep water drilling is massive, e.g., it requires horrendous amounts of energy before drilling even begins! Yet, on a bpd basis, the off-shore field could look excellent on the basis of "labor hours" alone.
I am totally lost by your last statement, "Energy balance calculations just account for the excess resource costs due to the consumption energy during the production of fuel." Excuse me? So, drilling, et.al., don't count when it comes to EROEI, just the energy used by a refinery? Now, I may have misinterpreted this so maybe you want to clearify it.
Todd
As an aside, the Yahoo Energy Resources forum has beaten EROEI into the ground for several years but has yet to find common ground.
First of all, how do you calculate total energy use in complex manufacturing processes? If it's possible to do so, why can't that sort of energy accounting be used as a model for larger systems of production? Unless of course someone wants to include the total background energy radiating throughout the entire universe in the calculations. I don't mean to be facetious but if the usefulness of the ratio EROEI is inversely proportional to the number of inputs one defines into the ratio then it would make sense to keep the number of inputs as limited as possible which raises another question. For what is the ratio useful? Shouldn't the questions be defined more precisely first, for example, what is EROEI in converting shale to oil versus extracting oil from tar sands in terms of natural gas consumed for a given quantity of oil produced? I'm not trying to trivialize an issue being debated by far more capable minds than my own, but it seems analogous to debating the question,"How useful is a spoon?"
Define "useful."
Arlo,
I'm getting frustrated at this point so I'm going to shut up for a while after this post.
The question is, How to define Energy Returned on Energy Invested? That is, how many joules do you get after the conversion or process compared to how many joules it took to run the process including other inputs. It has nothing to do with whether the joules are useful. It has nothing to do with economics.
It is simply joules out versus joules in. Let it go at that without trying to add other considerations or dimensions that aren't germane.
Todd
BTW, a spoon isn't useful because you can "slurp." Nor is a fork since you can use your fingers or a stick. The only thing a knife might be "useful" for is to cut up game. Otherwise, you can knaw.
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.