Ithaca, New York
August 6, 2001
Neither increases in government
subsidies to corn-based ethanol fuel nor hikes in the price of
petroleum can overcome what one Cornell University agricultural
scientist calls a fundamental input-yield problem: It takes more
energy to make ethanol from grain than the combustion of ethanol
produces.
At a time when ethanol-gasoline mixtures (gasohol) are touted as
the American answer to fossil fuel shortages by corn producers,
food processors and some lawmakers, Cornell's David Pimentel
takes a longer range view.
"Abusing our precious croplands to grow corn for an
energy-inefficient process that yields low-grade automobile fuel
amounts to unsustainable, subsidized food burning," says the
Cornell professor in the College of Agriculture and Life
Sciences. Pimentel, who chaired a U.S. Department of Energy
panel that investigated the energetics, economics and
environmental aspects of ethanol production several years ago,
subsequently conducted a detailed analysis of the corn-to-car
fuel process. His findings will be published in September, 2001
in the forthcoming Encyclopedia of Physical Sciences and
Technology.
Among his findings are:
- An acre of U.S. corn yields
about 7,110 pounds of corn for processing into 328 gallons of
ethanol. But planting, growing and harvesting that much corn
requires about 1,000 gallons of fossil fuels and costs $347
per acre, according to Pimentel's analysis. Thus, even before
corn is converted to ethanol, the feedstock costs $1.05 per
gallon of ethanol.
- The energy economics get worse
at the processing plants, where the grain is crushed and
fermented. As many as three distillation steps are needed to
separate the 8 percent ethanol from the 92 percent water.
Additional treatment and energy are required to produce the
99.8 percent pure ethanol for mixing with gasoline. o Adding
up the energy costs of corn production and its conversion to
ethanol, 131,000 BTUs are needed to make 1 gallon of ethanol.
One gallon of ethanol has an energy value of only 77,000 BTU.
"Put another way,"
Pimentel says, "about 70 percent more energy is required to
produce ethanol than the energy that actually is in ethanol.
Every time you make 1 gallon of ethanol, there is a net energy
loss of 54,000 BTU."
- Ethanol from corn costs about
$1.74 per gallon to produce, compared with about 95 cents to
produce a gallon of gasoline. "That helps explain why fossil
fuels -- not ethanol -- are used to produce ethanol," Pimentel
says. "The growers and processors can't afford to burn ethanol
to make ethanol. U.S. drivers couldn't afford it, either, if
it weren't for government subsidies to artificially lower the
price."
- Most economic analyses of
corn-to-ethanol production overlook the costs of environmental
damages, which Pimentel says should add another 23 cents per
gallon. "Corn production in the U.S. erodes soil about 12
times faster than the soil can be reformed, and irrigating
corn mines groundwater 25 percent faster than the natural
recharge rate of ground water. The environmental system in
which corn is being produced is being rapidly degraded. Corn
should not be considered a renewable resource for ethanol
energy production, especially when human food is being
converted into ethanol."
- The approximately $1 billion a
year in current federal and state subsidies (mainly to large
corporations) for ethanol production are not the only costs to
consumers, the Cornell scientist observes. Subsidized corn
results in higher prices for meat, milk and eggs because about
70 percent of corn grain is fed to livestock and poultry in
the United States Increasing ethanol production would further
inflate corn prices, Pimentel says, noting: "In addition to
paying tax dollars for ethanol subsidies, consumers would be
paying
significantly higher food prices in the marketplace."
Nickels and dimes aside, some
drivers still would rather see their cars fueled by farms in the
Midwest than by oil wells in the Middle East, Pimentel
acknowledges, so he calculated the amount of corn needed to
power an automobile:
- The average U.S. automobile,
traveling 10,000 miles a year on pure ethanol (not a
gasoline-ethanol mix) would need about 852 gallons of the
corn-based fuel. This would take 11 acres to grow, based on
net ethanol production. This is the same amount of cropland
required to
feed seven Americans.
- If all the automobiles in the
United States were fueled with 100 percent ethanol, a total of
about 97 percent of U.S. land area would be needed to grow the
corn feedstock. Corn would cover nearly the total land area of
the United States.
The web version of this release
may be found at
http://www.news.cornell.edu/releases/Aug01/corn-basedethanol.hrs.html
Cornell University News Service
Surge 3
Cornell University
Ithaca, NY 14853
607-255-4206
cunews@cornell.edu
http://www.news.cornell.edu
Cornell University news release
N3715
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