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Monday, April 04, 2005

Unwise Use of numbers

A fascinating talking points memo from the National Corn Growers Association web site suggests amazing energy returns from ethanol in comparison to gasoline. I find it fascinating because the memo states this in the upper right margin:

Office of Energy Efficiency and Renewable Energy
U.S. Department of Energy - Page 1

Argonne National Laboratory Ethanol Study: Key points

The title and masthead indicates that presumably someone (nameless) in some official capacity from this branch of the DOE authored the summary. Unfortunately, the memo contains some astounding claims, that if true, turns conventional understanding of our petroleum infrastructure on its head.

One of the key points from the summarized report make this rather alarming and quite unambiguous statement:
As you can see, the fossil energy input per unit of ethanol is lower -- 0.74 million Btu fossil energy consumed for each 1 million Btu of ethanol delivered, compared to 1.23 million Btu of fossil energy consumed for each million Btu of gasoline delivered.
This relationship perfectly illustrates a mathematical conundrum. At one limit, if the 1.23 million BTU's comes from the petroleum itself, then you would never get any gasoline to the consumer. Everything you pull out of the ground would get completely used up (and then some) to get to the filling station. But we know that we can't use that limit as the study says that the 1.23 million comes from all sources of fossil fuel (coal, natural gas, etc).

So next we have to ask how the relationship pans out for coal. Why doesn't the author from Argonne point out how many millions of BTU of fossil fuel energy it takes to deliver 1 million coal BTUs? Well, he won't because he will find himself trapped inside a trick-box. If the number turns out higher than 1 million BTUs, then his argument collapses into an impossibility. We would use up more energy than we get out (and we know this can't be true). On the other hand, if it is lower than 1 million BTUs, then coal suddenly looks like a better energy delivery vehicle than petroleum. (If we can endure the dirty air, maybe it is?) Instead of ethanol, perhaps we should resort back to steam locomotion as a means of transportation.

I believe we need to look at the original study. Argonne scientists usually publish their findings in peer-reviewed scientific journals. If they don't, they should not work at a U.S. government basic research lab.

For all we know some bureaucrat might have cherry-picked the key points without the negatives to make it look good. Worse yet, somebody at the corn growers association may have spun the original report to favor ethanol. I could not locate it on the http://www.eere.energy.gov web site.

Pops from the PeakOil message board interpreted the data as reading 0.23 million instead of 1.23 million, implying that they meant some sort of net overhead. But notice that they (i.e. the original "authors" from the Office of Energy Efficiency and Renewable Energy) use the word "consumed". Now if "consumed" in one case meant "handled", I could buy into his interpretation. Then we can chalk it up to bad grammar or syntax (imagine if George Bush had tried to articulate this).

Obligatory disclaimer: Great news if the numbers do indeed pan out!

The key points memo cites a scientist from Argonne named Michael Wang as the author of the original study. Apparently, Wang sits on the Board of Directors of the Energy Foundation, a non-profit dedicated to finding energy alternatives. I feel a tad more confident that we will eventually get to the bottom of the strange numbers as a particularly outspoken opponent of the Energy Foundation is Mr. Wise Use himself, Ron Arnold. Arnold authored a book called Undue Influence in which he accuses Energy Foundation of accepting money from every oil company except for Exxon/Mobil, implying that the foundation only exists to undermine Exxon.

To paraphrase an old saying, I hope the enemy of our enemy is our friend.


Professor Anonymous Randell Jesup said...

The author certainly wants to make a point, but you're misreading what he says.

1.23 MBTU of fossil energy to produce 1 MBTU gasoline means that including the energy of the raw oil 1.23 MBTU were pulled from the ground to generate the 1 MBTU of gas. This means that in addition the energy in the final result, there was an additional 0.23 MBTU used in retrieving it, refining it, transporting it (I assume), waste, etc.

0.74 MBTU of fossil energy to produce 1 MBTU of ethanol means that if this is correct, you can draw less oil from the ground, use it to grow whatever and turn it into ethanol and transport it, and be around 0.5 MBTU ahead of petrogas (so far as the draw on the oil/coal reserviors goes) to get 1 MBTU to the pumps. If, instead of fossil fuels, you use ethanol to generate ethanol, you need to produce around 2.5 MBTU total. (That 0.74 MBTU to get 1MBTU of ethanol requires 0.74*0.74 MBTU to produce. That requires likewise, etc.)

This begs the question: is this calculation correct? Other ones I've read (second-hand!) state that ethanol is a net energy loss, at least from corn (i.e. >1 MBTU fossil fuels to generate 1 MBTU, and probably >1.23 MBTU fossil fuels.) Biodiesel from algae in the desert, on the other hand might be just fine.

3:11 PM  
Professor Blogger WHT said...

"As you can see, the fossil energy input per unit of ethanol is lower -- 0.74 million Btu fossil energy consumed for each 1 million Btu of ethanol delivered, compared to 1.23 million Btu of fossil energy consumed for each million Btu of gasoline delivered."

Apparently I didn't misread what the author wrote, the author totally screwed up in writing what he intended to convey. Both the ethanol and gasoline comparisons have an energy "consumed" comparison. If you are right and the more I think about it you probably are then this author's whole piece was poorly written.

1:52 AM  
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