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Alternative Energy Basics
ETHANOL MADE FROM CORN AND OTHER CROPS
Ethanol is a
clear, colorless alcohol fuel made from the sugars found in grains,
such as corn, sorghum, and wheat, as well as potato skins, rice,
and yard clippings. Ethanol is a renewable fuel because it is made
from plants. There are several ways to make ethanol from biomass.
The most commonly used processes today use yeast to ferment the
sugars and starch in corn. Corn is the main ingredient for ethanol
in the United States due to its abundance and low price. Most ethanol
is produced in the corn-growing states in the Midwest. The starch
in the corn is fermented into sugar, which is then fermented into
alcohol. Other crops such as, barley, wheat, rice, sorghum, sunflower,
potatoes, sugar cane and sugar beets can also be used to produce
Sugar cane and
sugar beets are the most common ingredients for ethanol in other
parts of the world. Since alcohol is created by fermenting sugar,
sugar crops are the easiest ingredients to convert into alcohol.
Brazil, the country with the world's largest ethanol production,
makes most of its ethanol this way. Today, many cars in Brazil operate
on ethanol made from sugar cane.
A new experimental
process which breaks down cellulose in woody fibers, is called "cellulosic
ethanol". With this process we can make ethanol from trees, grasses,
and crop wastes. Trees and grasses need less energy than grains,
which must be replanted every year. Scientists have developed fast-growing
trees that grow to size in ten years. Many grasses can produce two
harvests a year for many years. Someday, you may find yourself driving
by huge farms that are not producing food or animal feed, but feedstock
for ethanol. Feedstock is the raw material used to make a product.
Ethanol is not
a new fuel. In the 1850s, ethanol was a major lighting fuel. During
the Civil War, a liquor tax was placed on ethanol to raise money
for the war. The tax increased the price of ethanol so much that
it could no longer compete with other fuels such as kerosene in
lighting devices. Ethanol production declined sharply because of
this tax and production levels did not begin to recover until the
tax was repealed in 1906.
In 1908, Henry
Ford designed his Model T to run on a mixture of gasoline and alcohol,
calling it the fuel of the future. In 1919, when Prohibition began,
ethanol was banned because it was considered a liquor. It could
only be sold when it was mixed with petroleum. With the end of Prohibition
in 1933, ethanol was used as a fuel again. Ethanol use increased
temporarily during World War II when oil and other resources were
scarce. In the 1970s, interest in ethanol as a transportation fuel
was revived when embargoes by major oil producing countries cut
gasoline supplies. Since that time ethanol use has been encouraged
by offering tax benefits for producing ethanol and for blending
ethanol into gasoline. In 1988, ethanol began to be added to gasoline
for the purpose of reducing carbon monoxide emissions. Learn more
about the history of ethanol in a timeline.
AS A TRANPSORTATION FUEL
As a transportation
fuel, ethanol can be used as a total or partial replacement for
Gasoline containing ten percent ethanol - E10 - is used in many
urban areas that don't meet clean air standards. Some states promote
more widespread use of E10. Minnesota, for example, requires almost
all gasoline sold in the state to contain 10 percent ethanol. All
vehicles that run on gasoline can use E10 without making changes
to their engines. Over 99 percent of the ethanol produced in the
United States is mixed with gasoline to make E-10.
E85 is an alternative
fuel that is 85 percent ethanol and 15 percent gasoline, used
mainly in the Midwest and South. Vehicles are not modified to run
on E85; they are specially manufactured as flexible fuel vehicles
(FFV). Flexible Fuel Vehicles can use any mixture of ethanol and
gasoline up to E85. There are about 146,000 cars and trucks using
E85. Most of these are fleet vehicles.
and the Environment
means that we use a little bit less oil (a nonrenewable fuel) to
make gasoline. Unlike gasoline, ethanol is
nontoxic (safe to handle) and biodegradable, it quickly breaks down
into harmless substances if spilled. When small amounts of ethanol
are added to gasoline, usually less than 10 percent, there are many
advantages. Ethanol reduces carbon monoxide and other toxic pollution
from the tailpipes of vehicles, making the air cleaner. It keeps
engines running smoothly without the need for lead or other chemical
additives. Because ethanol is made from crops that absorb carbon
dioxide and give off oxygen, it has the potential to reduce greenhouse
gas emissions and help maintain the balance of carbon dioxide in
the atmosphere. This process is called the carbon cycle.
Last Revised: October 2007
Sources: Energy Information Administration, Annual Energy Review
2006, June 2007.
The National Energy Education Development Project, Alternative
Fuels: What Car Will You Drive?, 2007.
U.S. Department of Energy, Energy Efficiency and Renewable Energy,
Clean Cities Fact Sheet- Low Level Ethanol Fuel Blends