The Ethanol Debate
Is the drive towards agricultural ethanol production a
By Walter H. Schneider
The September 19, 2006 issue of the Edmonton Journal carried a small article
titled "Researchers unveil ethanol-only tractor" (p. A5). The article
The Saskatchewan Research Council
has unveiled a prototype of what it
says is the first tractor to run entirely
Ethanol is a a high octane, water-
free alcohol made primarily from
and other renewable agricultural stock.
The year-long project involved
converting a regular 20-year-old
tractor to the more energy-efficient
The article triggers two concerns.
- If a tractor running on ethanol can be made to be more energy efficient,
should it then not be possible to do the same also with one running on diesel?
The reality of that is that, unless someone comes up with an remarkable
technological break-through, Diesel engines cannot be made to be more energy
efficient than they are. Moreover, it is not likely that a Diesel
engine running on ethanol can be substantially more efficient than one
running on Diesel fuel. However, a
far more important concern is that,
- Agricultural ethanol production for motor fuel is far from being a clear
and obvious solution to alleviate shortages of energy supplies.
- About 71% more energy is required to produce a gallon of ethanol
than the energy that is contained in a gallon of ethanol. (Pimentel,
1998) The ratio of production of energy vs. input of energy for
energy produced from fossil fuel is perhaps worse, but it does not
require the vast area of crop land to satisfy the requirements if
ethanol were used to replace all conventional motor fuel for cars.
- To fuel one car with ethanol for one year means that nearly 7-times
more cropland would be required to fuel one car than is needed to feed
one American (USDA, 1996).
Assuming a net production of 50 gallons of fuel per acre of corn,
and assuming that all cars in the United States were fueled with
ethanol, a total of approximately 2 billion acres of cropland would be
required to provide the corn feedstock. This amount of acreage is more
than 5-times all the cropland that is actually and potentially available
for all crops in the future in the United States. (Pimentel, 1998)
Running on empty? 'Great ethanol debate' waged at NCGA
([US] National Corn Growers Association) forum
Does making ethanol consume more energy than it produces? Will ethanol be
a key component in helping the nation reduce its voracious appetite for
foreign oil, or just be a bit player on the energy front?
That's been the subject of an intense debate for years, and two panels of
experts squared off recently to try to settle the question. The experts
presented starkly differing views during "Ethanol Energy Balance," an open
forum held Aug. 23 at the National Press Club in Washington, D.C., sponsored
by the National Corn Growers Association (NCGA)....
In a paper he published in 1998, Energy and Dollar Costs of Ethanol
Production with Corn, [David Pimentel, Ph.D.] says:
“Assuming a net production of 50 gallons of fuel per acre of corn, and
assuming that all cars in the United States were fueled with ethanol, a
total of approximately 2 billion acres of cropland would be required to
provide the corn feedstock. This amount of acreage is more than five times
all the cropland that is actually and potentially available for all crops in
the future in the United States.”
Pimentel spoke to a largely pro-ethanol crowd of corn producers and their
representatives. Ethanol, he said, is not a true renewable energy source,
because it requires more energy in its production than is extracted from the
finished product. According to his calculations, ethanol takes about 1.15
BTUs (British Thermal Units) of input for every 1 BTU of output. [Full
The ethanol advocates' responses in that debate focused on Pimental’s
cost/benefit formula. The criticism's were such as that,
- Pimentel’s methodology assumes inputs that are too high;
- The concept of net energy is a false standard;
- Biofuels are not a silver bullet for the energy industry, but could
replace 70 percent of the petroleum used for fuel and other purposes;
- Many studies contradicted the claims of Pimentel and Patzek;
- Pimentel [and Patzek used] extraneous data in their calculations, such
as the food eaten by farmers and workers engaged in ethanol production and
the energy cost of building farm machinery, and that
- The studies by Pimentel and Patzek were not peer-reviewed before
Those criticisms appear to be quibbles. If any of the figures used by
Pimentel and Patzek are not sufficiently accurate, let's work on getting better
and more accurate figures into the models for all energy source comparisons, but
lets make sure that we agree on what common standard measures to use for
comparisons of alternatives.
At any rate, reading Stephen Thompson's account of the debate, it struck me
that no one disputed the apparently most important concern expressed by Drs.
Pimentel and Patzek, namely that in order to produce sufficient bio fuel so as
to make a reasonable dent into petroleum consumption merely for fuels for cars,
an inordinate and unaffordable amount of agricultural acreage would have to be
taken out of food production and devoted to motor fuel production. After
all, even if we were to replace only 20 percent of motor fuel produced from
fossil fuels with ethanol from agricultural production, that would require more
than the acreage currently used for food production.
Stephen Thompson's account of the debate did not identify any arguments that
disagreed with the claim that it takes more energy to produce a gallon of
ethanol than that gallon of ethanol can provide. That should make it clear
that to even replace 20 percent of current fossil fuel consumption for road
transportation with ethanol would require more acreage of crop land than is or
will be available for the production of ethanol.
Certainly, if enough cropland currently used for food production is devoted
to fuel production, the price of corn will soon reach levels that make it
unaffordable to use ethanol for motor fuel.
As to the criticism that the studies by Drs. Pimentel and Patzek (2)
were not peer-reviewed, that appears to be a somewhat spurious argument.
Scientific truth is not a matter of consensus. One right answer, no matter
how much it contradicts previously held beliefs relating to a given subject,
makes all those previously held beliefs invalid. After all, there was at
one time a consensus that the Earth was flat and the centre of the Universe.
The truth in that matter was promoted against very great odds and against
massive opposition, but it prevailed.
On a more practical level, being as addicted as we are to fossil fuel
consumption, it won't do much good to depend on diminishing sources of fossil
fuels. Yes, there are alternative sources of fossil fuels that will keep
us supplied with conventional motor fuels for perhaps a thousand years or more.
The only thing that kept us from developing those sources is supply and demand.
As long as it is cheaper to import petroleum from overseas than it is to develop
fuels from alternative fossil fuel sources, we will keep importing petroleum.
A big advantage of fossil fuel production from alternative sources is that it
will not take any or at worst only very little crop land used for food out of
Pimentel and Patzek suggest that we need to reduce energy consumption.
Agricultural crop production once was far less energy intensive. That was
when machinery was still horse powered. A rule of thumb at that time was
that about one quarter of crop land production was required to feed the horses
that were used to sow and harvest crops. Perhaps that's what they
have in mind, but it seems hardly feasible to return to that sort of production
method. Still, their energy comparisons did not cover that alternative.
Yet, that would be the only method of production that consistently provides
positive energy returns when growing crops and converting them to biofuels.
- ENERGY AND DOLLAR COSTS OF ETHANOL PRODUCTION WITH
David Pimentel; HUBBERT CENTER NEWSLETTER # 98/2 [Link
PDF file, 37kB]
- Ethanol Production Using Corn, Switchgrass, and Wood;
Biodiesel Production Using Soybean and Sunflower
By David Pimentel and Tad W. Patzek, Natural Resources Research, Vol. 14,
No. 1, March 2005 (© 2005), DOI: 10.1007/s11053-005-4679-8 [Link
PDF file, 114kB]
Posted 2003 01 21
2003 05 06 (added reference to comparison of results
of modelling used to assess the accuracy of actual global temperature measurements)