The complete text of my e-mail response to Cecil:
Hi Cecil. I’m a longtime reader and fan.
I realize that you can’t debate something as complex as energy
policy, let alone farm subsidies and the environment, in a thousand
words. Still, I thought I should mention some deeper facts on the
subject of ethanol.
Pimintel’s assumptions about ethanol production were correct in 1980,
and certainly 1973. However, he was found to be reusing that data
well into the '90s. Many changes have occured in industrial
processes in the past twenty years.
Please see “Fuel Ethanol Production from Midwest US Corn:
Help or Hindrance to the Vision of Kyoto?” by Wang, Saricks, and Wu.
It’s in the Journal of the Air & Waste Management Association,
vol. 49, p. 756 (July 1999). Wang, Saricks, and Wu are researchers
at Argonne National Labs, ouside of Chicago. I know that that makes
them immediately suspect as corn sympathysers, but I think Argonne
National Labs is about as politically-neutral an institution as
you’ll find in Chicago. Both Wang et al, and the studies they cite,
were peer-reviewed. At the very least, the three were not paid to
do the study by any industry group or lobby (agribusiness or
What’s most important is that the paper is a metastudy, reviewing a
decade’s worth of the ethanol question. The three point out the
pro’s and con’s of a diversity of studies, including Pimintel’s
latest, and a joint Department of Agriculture/Department of Energy
study. They conclude that the answer is somewhere in the middle-
between the optimistic and pessimistic energy balances, the most
accurate assumptions point to a slightly positive energy balance in
the conversion of corn to ethanol.
I’ll highlight the key points:
-Pimintel makes some broad assumptions. He assumes that 100% of corn
acreage is under irrigation. This is important because irrigation
pumps currently use diesel fuel. Wang, Saricks, and Wu point out
that of the four major corn-producing states studied- Illinois, Iowa,
Minnesota, and Nebraska- Illinois and Iowa have negligible acreage
under irrigation, and the worst state in this regard (Nebraska)
varies by region.
-Fuel usage in the form of fertilizer has dropped drastically
through the '90s. This is due to efficiencies within the fertilizer
industry, and reduced application by farmers (“precision farming”).
Pesticide production and application have shown no noticeable trend.
-The energy usage by ethanol facilities has also dropped by a
significant fraction. Since Pimintel’s 1980 study, molecular sieves
(“zeolites”) and polysaccharides (the Ladisch-Tsao process) have
almost eliminated the azeotropic process, reducing the energy
requirements of distillation. Wang, Saricks, and Wu note that
molecular sieves are the dominant dehydration method, with a few
holdouts not upgrading from azeotropes.
-The largest and least-disputed benefit is in reduced petroleum
importation. The ethanol processes are heat-driven, which is most
effectively done with natural gas. Natural gas is almost entirely
domestic in origin, and quite clean. Some older plants use coal,
which is dirtier, but also domestic. The remaining petroleum usage
is in tractors, corn and ethanol transport, and irrigation pumps,
but these too have become more efficient in the past twenty years.
-Net reduction of greenhouse gases depends on the facility, but is
overall positive. Natural-gas fired facilities are of course
cleaner, but overall the industry is a net greenhouse benefit.
I agree with Pimintel on one point: we must reduce fuel usage,
period. Usage of petroleum, ethanol, natural gas, etc. In other
writings, Pimintel advocates more-efficient vehicles and industries,
Also note that ethanol is also produced from potato-
processing scraps and excess paper pulp, which would
otherwise be waste products. The energy balances
of these are debateable, since what amount of energy
would you assign to the parent product? Still, the
net energy is positive given any reasonable energy
(Not funded by any interest- I’m a NASA engineer)