Ethanol from corn (was Kuwait oil)

From: Kenneth Piers <>
Date: Wed Nov 16 2005 - 07:17:17 EST

Friends: The short answer to the question of how much land would be necessary
to replace our gasoline use with ethanol is "more land than is available".

Here are some numbers I used in my course on energy resources at Calvin this
Total gasoline used in US 2004 = 145 billion (B) gal (this does not include
diesel fuel or aviation fuel)
Average ethanol yield per acre of corn = 315 gal (average corn yield = 137
bu/acre; average yield of ethanol from corn = about 2.3 gal/moist (15% water)
Ratio of heat of combustion of gasoline to ethanol = (about) 1.5/1 - actually
1.57/1 - (ie, you need to burn about 1.5 gal of ethanol to liberate the same
amount of heat energy as burning 1 gal of gasoline)
So, to replace 145 B gal of gasoline we would need about 217.5 B gal of
ethanol per year
At 315 gal of ethanol/acre this would require that we grow 690 M acres of corn
for ethanol production.
The total cropland planted in the US in 2003 was about 450 M acres.
This calculation neglects the fact that if we were to greatly expand our corn
growing more gasoline would be required. Nor does this calculation take into
account net energy.
Obviously we do not have enough land to replace gasoline with ethanol using
corn as the feedstock. Replacing even 10% of the gasoline with ethanol would
require that 69 M acres of corn would need to be devoted to ethanol production.
In 2004 a total of 74 M acres of corn was harvested in the US.
In 2004, we produced about 3.25 B gallons of ethanol from corn requiring that
some 10.3 M acres of corn land was devoted to ethanol production. It seems very
unlikely to me that corn to ethanol (or, in fact, most any biomass to liquid
fuel) program could ever replace a substantial fraction of the gasoline we use.

ken piers

Ken Piers

"We are by nature creatures of faith, as perhaps all creatures are; we live by
counting on things that cannot be proved. As creatures of faith, we must choose
either to be religious or superstitious, to believe in things that cannot be
proved or to believe in things that can be disproved."
Wendell Berry

>>> Glenn Morton <> 11/15/2005 4:56 PM >>>
Email is so bad in this apartment. third try to send this.
  I have this in my database from a 2001 source. 1 acre produces 328 gallons
of ethanol. But one must take into account transportation costs before
figuring out how much of this will fuel the autos. Gas has energy content of
12000 kcal/liter while ethanol has 5100 kcal/liter. So, we will need more
ethanol than gasoline. Today the US uses 9 million barrels of ethanol
(something like 350 million gallons). I won't calculate the acreage required
cause I have spent way too much time on this one email but the acreage would be
  For those who question this topic, I would say this. Since the ASA invited
me to give a talk at their Aug conference on this issue, it seems to me that we
should be able to discuss things on this list which were found suitable for the

Tjalle T Vandergraaf <> wrote:
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 w\:* {behavior:url(#default#VML);} .shape {behavior:url(#default#VML);}
 st1\:*{behavior:url(#default#ieooui) } Biodiesel and ethanol
are viable alternatives as long as the energy balance is positive but I wonder
how many acres we need to plant with corn etc. to offset the decrease in fossil
fuel harvesting. Hopefully, somebody has an answer. But, what with the
vagaries of farming (Canadian prairie farmers have had a rough couple of
years), I wonder how secure a biofuel supply would be.

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Received on Wed Nov 16 07:18:45 2005

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