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ETHANOL
& ENERGY
Ethanol
Production: A Net Energy Winner
There is clearly no doubt that fuel ethanol contains more energy than
it takes to produce.
In June 2004, the
U.S. Department of Agriculture updated its 2002 analysis of the issue
and determined that the net energy balance of ethanol production is
1.67 to 1. (For every 100 BTUs of energy used to make ethanol, 167 BTUs
of ethanol is produced.) In 2002, USDA had concluded that the ratio
was 1.35 to 1.
The USDA findings
have been confirmed by additional studies conducted by the University
of Nebraska and Argonne National Laboratory. In fact, since 1995, nine
independent studies found ethanol has a positive net energy balance,
while only one study – which used outdated data – found
the energy balance to be negative.
A Michigan State
University study (2002) found that ethanol produced from corn provided
56 percent more energy than is consumed during production (1.56 to 1).
This study looked at producing ethanol from both dry and wet milling
of corn—and included corn grain production, soybean products from
soybean milling and urea production.
These studies take
into account the entire life cycle of ethanol production—from
the energy used to produce and transport corn to the energy used to
produce ethanol to the energy used in the distribution of ethanol in
gasoline.
What’s behind
this continual increase in net energy balance?
Production efficiency
is one factor. Compared to just five years ago, today’s ethanol
plants produce 15 percent more ethanol from a bushel of corn—and
using 20 percent less energy in the process.
The energy efficiency
of American farmers is another reason. According to USDA statistics,
U.S. agriculture uses about half the energy to produce a unit of output
today than was needed to produce the same output in 1950.
Better corn varieties,
improved production practices and conservation measures also figure
into the equation. A 1 percent increase in corn yield raises the net
energy value by 0.37 percent.
It’s also
important to note that energy from ethanol is not the only result of
ethanol production. Coproducts such as distillers grains, gluten feed,
carbon dioxide, and corn sweeteners are also created in ethanol production.
That means that not all the energy used by an ethanol plant is directed
at manufacturing ethanol, thus further improving the net energy balance
of ethanol production.
Ethanol opponents
frequently cite a study by Cornell University’s Dr. David Pimentel,
who concluded that it takes 70 percent more energy to produce ethanol
than it yields. Pimentel’s findings have been consistently refuted
by USDA and other scientists who say his methodology uses obsolete data
and is fundamentally unsound.
America's
Dependence on Oil Imports
Analysis by the U.S. Department of Energy and USDA shows that, for every
100 BTUs of energy used to make ethanol, 135 BTUs of ethanol is produced.
That is a positive net energy balance of 1:1.35.
A more
recent Michigan State University study (2002) underscores these findings.
In the MSU study, ethanol produced from corn was found to provide 56%
more energy than is consumed during production. This study looked at
producing ethanol from both corn wet and dry milling—and included
corn grain production, soybean products from soybean milling and urea
production.
These
studies take into account the entire life cycle of ethanol production—from
the energy used to produce and transport corn, to the energy used to
produce ethanol, to the energy used in the distribution of ethanol in
gasoline.
Additionally,
U.S. agriculture has become more energy efficient. According to USDA
statistics, U.S. agriculture uses about half the energy to produce a
unit of output today than was need to produce the same output in 1950.
Ethanol
opponents frequently cite a study by Cornell Professor David Pimentel,
who concluded that it takes 70% more energy to produce ethanol than
it saves. Pimentel’s findings have been consistently refuted by
USDA and other scientists who say it uses obsolete data and is fundamentally
unsound.
Future
Role of Ethanol
Ethanol is uniquely
positioned to grow in importance as the nation continues its quest for
renewable energy and new engine technologies.
E85:
This blend of 85 percent ethanol and 15 percent ordinary unleaded gasoline
has become a rapidly growing alternative fuel since the dramatic increase
in gas prices. Millions of vehicles on American highways can operate
on E85. These flexible fuel vehicles (FFVs) can actually operate on
E85, E-10 Unleaded, ordinary unleaded or any combination of these fuels.
A computer in the fuel system automatically adjusts for the amount of
ethanol in the blend.
The number of E85 fueling
stations across the United States is growing at an accelerated rate—and
U.S. automakers are manufacturing a larger number of FFVs.
Obviously, replacing 85 percent
of the petroleum in a gallon of gasoline will help America wean itself
from imported oil even faster—and create a greater demand for
ethanol in the nation’s fuel supply.
Ethanol-Based
Aviation Fuel: Extensive research has shown that an aviation
fuel blend containing 85 percent ethanol offers superior performance
in prop-driven aircraft. The Federal Aviation Administration and several
universities are conducting research on ethanol-based aviation fuel
to determine the feasibility of the fuel as an alternative to the leaded
aviation fuel currently being used.
E diesel:
Off-road equipment, city buses and other vehicles that run
on diesel fuel are major contributors to air pollution. Research is
under way to discover the optimum blend of ethanol and diesel fuels
to replace straight diesel fuel in these engines. The cities of Lincoln,
Neb.,, and Springfield, Ill., as well as Johnson County, Kan., have
converted their city bus fleets to an E diesel blend on a test basis—and
other cities in the Midwest are considering similar tests.
Fuel Cells:
This is the next evolution in engine technology—and ethanol is
poised to become an integral part of this new wave of automotive innovation.
Fuels cells work by combining hydrogen and oxygen in a chemical reaction
to create electricity, without the noise and pollution of conventional
engines. Ethanol is a hydrogen-rich liquid with a simple molecular structure—offering
a practical, economical and efficient solution as a hydrogen source
for onboard fuel cells in vehicles or stationary applications.
Biomass
Sources: While starch from the corn kernel is the feedstock
of choice for ethanol production, the industry may soon have the capability
to efficiently convert crop residues such as corn stalks and cobs into
ethanol. Other raw materials such as trees, grasses, and other agricultural
crops can also be used to derive ethanol. These biomass sources may
eventually be used in ethanol production facilities that are located
where corn production is not prevalent.
Last
reviewed June 10, 2005
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