From: Glenn Morton (email@example.com)
Date: Mon Jan 20 2003 - 16:30:36 EST
You wrote on Sunday, January 19, 2003 11:24 PM
>Glenn: I found the following at the www.whybiotech.com website:
>Higher Corn Yields are Making Ethanol More Energy Efficient
>New USDA study says ethanol now yields 34 percent more energy than
>to produce it.
>A recent U.S. Department of Agriculture study found that ethanol
>is becoming more energy-efficient all the time because corn yields are
>rising, less energy is required to grow it, and ethanol conversion
>technologies are becoming more efficient.
>Is this consistent with the views of the oil industry? What might be the
>limitations of replacing gas derived from oil with gas derived from corn?
First, let me state that the opinions I express are mine not the oil
industry's. I don't know if it has an opinion, but if it does, it hasn't
given it to me. :-)
Seconly, I got the original US Ag dept article this morning and read it on
the plane to London today. The article has some interesting comments.
First, they are correct that improving efficiencies are closing the gap
between energy positive and energy negative positions. However, there are a
couple of things they omit or ignore which tell me that they haven't yet
shown that the manufacture of ethanol is energy positive yet.
Their table 6 summarizes the situation:
Process BTU/gallon ethanol
Corn production 21,598
Corn transport 2,263
Ethanol Conversion 51,779
Ethanol distribution 1,588
Total energy used 77,228
Given an 83,9600 btu/gallon energy content of Ethanol they come up with a
net energy value of
+6,732 BTU per gallon.
It is interesting what they leave out of the calculations. They state:
"Another major difference between the Pimentel studies and most other
studies is that his estimates include energy expended on capital equipment.
Pimentel's estimate for converting ethanol is about 7,000 Btu/gal higher
because it includes energy for steel, cement, and other materials used to
construct the ethanol plant, components not included in most other studies."
Hosein Shapouri and James A. Dulfield and Michael Wang," The Energy Balance
of Corn Ethanol: An Update", USDA AER-814, (2002), p. 3
And then they don't include this in their estimate of the economics of
ethanol either. Thus, they are implicitly assuming that one doesn't have to
spend energy on the plant itself in this equation! Leave it to government
bureaucrats to ignore capital investment! Correcting for this, one
immediately takes their 'uncredited calculation' into the red.
Secondly, they then credit the calculation by taking the waste products and
treating them as energy positives. They are energy positives, but they are
not fuel oil. The coproducts are distiller's dried grains, corn oil, corn
gluten meal and corn gluten feed. I find this a bit misleading to the public
because it is taking advantage of the conservation of energy to act as if we
are getting useful fuel from an energetically advantageous process. If we
accounted for all the energy in all the systems, we would have all the
energy after the processing of ethanol.
One other worry I have about this paper is that they claim 80% efficiency
for gasoline and diesel in transportation. That seems about 4x too high
from what I know of transporation efficiencies.
I also noted a pattern in all the studies they cited. All but one of the
private papers said the process was negative. All studies published by the
government or lobbying groups say it is positive. Not exactly a comforting
pattern given that this is a government report.
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