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Corn Residue
In the
United States, after the massive combines sweep the millions of acres of corn in the fall and
remove the kernels, what is left are millions of tons of stalks, cobs, husks and
leaves of the corn plants?
Although this leftover material,
called corn stover, provides nutrients for the soil and prevents erosion, it
also has the potential for a new use: making ethanol.
Purdue University scientists say they
believe they can put some of this corn stover to use as a fuel for automobile
engines by converting it to ethanol.
Ethanol can be used to boost octane
and reduce engine knock, and it also can be blended with gasoline to make an
environmentally friendly fuel. Currently ethanol can only be made in industrial
quantities from starch extracted from corn kernels.
However, Michael Ladisch,
distinguished professor of agricultural and biological engineering, and
biomedical engineering, together with colleague Nancy Ho, research molecular
biologist, have developed a pre-treatment process that can also convert the
fibre left over when the starch is processed out of the corn kernel. The process
uses genetically engineered yeast, which were developed by Ho.
Now Ladisch says the process is ready
for development with corn stover.
Corn stover fibre is different from
the fibre found in the kernel. However, both materials contain cellulose, which
can be converted into sugars, which can then be fermented into ethanol.
The research is being conducted in
Purdue's Laboratory of Renewable Resources Engineering (LORRE, pronounced
"Lori"), an integrative centre
for biotechnology and engineering.
To aid this next step in ethanol
research, the Indiana Department of Commerce has given LORRE an $80,000 grant to
modify the process. Pilot-scale testing of the new process will be conducted at
the Williams Bio-Energy facility in Pekin, Ill.
Making fuel from the corn stover could
benefit Indiana's economic development, says Indiana Lt. Gov. Joe Kernan.
"Finding ways to produce ethanol
more efficiently by using our own agricultural resources is important to
Indiana's economy," he says. "This grant promotes this goal while
helping Indiana take a leadership position in the critical biotech
industry."
Kernan also serves as director of the
Indiana Department of Commerce, which made the grant to Purdue, and as the
state's commissioner of agriculture.
Ladisch says developing a process that
uses existing industrial equipment is a key to getting the technology accepted
by the ethanol industry. "Then this process has the potential to greatly
increase the amount of ethanol that will be produced from non-grain
sources," he says.
To enhance the process, Jonathan
Wilker, assistant professor of chemistry; and Nathan Mosier, graduate student,
are in the process of developing new catalysts that mimic organic enzymes that
convert cellulose into sugars that can be fermented into ethanol.
In addition to the work being done at
Purdue, scientists at Williams Bio-Energy, the National Renewable Energy
Laboratory and the U.S. Department of Agriculture's National Centre for
Agricultural Utilization Research are working with the Purdue scientists to
adapt the process to commercial production.
The need for ethanol is increasing.
Ethanol can be used in automobile engines as a replacement for methyl tertiary
butyl ether (MTBE), which is a chemical derived from petroleum that is used to
boost octane levels in gasoline. MTBE itself was a replacement for tetraethyl
lead, but like the lead compound, scientists have found MTBE causes
environmental damage, and the U.S. Environmental Protection Agency is phasing
out its use.
According to the Renewable Fuels
Association, in 2001 the United States made a record 1.77 billion gallons of
ethanol.
But the U.S. Department of Energy's
National Renewable Energy Laboratory estimates that converting one-third of the
nation's corn stover to ethanol could produce an additional 5 billion to 8
billion gallons of ethanol, enough to have a significant effect on the amount of
petroleum used in this country.
Nationally, about 244 million tons of
corn stover is produced each year; more than 22 million tons are produced
annually in Indiana.
Finding a market for corn stover could
mean $10 more per acre for farmers, according to the National Renewable Energy
Laboratory.
However, Purdue Extension corn
specialist Bob Nielsen cautions that before farmers strip their fields of corn
stover more needs to be known about the economic and agronomic effects.
"Crop residues provide benefits
in terms of erosion control and soil moisture conservation in no-tillage
systems. Corn stover also provides nutrient recycling in the soil as it
decomposes," Nielsen says. "The potential value for harvesting the
stover for ethanol production would require gross returns to the farmer in
excess of the cost of any additional nutrients that would be needed."
Purdue is a national leader in
developing new technologies to enhance the production of ethanol.
One such process, developed by Ladisch,
uses modified ground corn grits to remove water from ethanol. This
environmentally friendly, low-cost technique replaces methods that use chemicals
such as benzene or cyclohexane. The Purdue-developed method is being used in the
United States by companies such as Archer Daniels Midland and by other companies
around the world.
Nancy Ho developed a type of
genetically modified yeast that can convert sugars other than glucose, which is
made from cornstarch, into ethanol. When other materials, such as corn stover,
tree leaves, grass clippings or wood chips are broken down; they produce other
sugars, such as pentose and hexoses. Ho's yeast converts these sugars to
ethanol, too. In 1998, R&D Magazine selected this breakthrough as one of the
top 100 significant research developments of that year.
Related Web sites:
http://www.agriculture.purdue.edu/AgComm/public/agnews/
http://www.ethanolrfa.org/
http://www.ncaur.usda.gov/
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Brazil
Biodiesel - Soy Oil Stocks
A plan to mix five percent soy-based biodiesel into
all petroleum diesel sold at the pump in Brazil would consume 300,000 tonnes of
soy oil annually, the Vegetables Oils Industries Association (Abiove) said.
Brazil, the world's second soy oil producer and exporter after the United
States, should produce about 4 million tonnes of soy oil and export 1.5 million
in 2001. National stocks stood at 243,000 tonnes by the end of October.
"I hope that the legislation is in place within the next 12
months," said Carlo Lovatelli, Abiove president and president of Bunge
Limited's Brazilian arm.
"Technically there is no problem with implementation of the
programme."
But Lovatelli said it may take longer. The draft bill will have to pass
through a review process at several government ministries and the presidential
elections next October are likely to slow work on its approval.
Brazil has already constructed plants capable of industrial production of
the clean burning soy oil and ethanol-based fuel that has been tested over the
past year in the city bus fleet of Curitiba, the capital of the No.2 soy state
of Parana in Brazil's south.
A 20 percent mixture of biodiesel in Curitiba's bus fleet has reduced the
city's total air pollution by 20 to 25 percent from the same period last year.
Lovatelli estimates five percent of the green fuel in the nation's entire diesel
could cut pollution by roughly 27 percent in the big cities.
"And the additive would require no engine modification," added
Lovatelli.
"Brazil's interests would be best served if we could diversify our
energy matrix. We are still an oil importer and 65 percent of the world's oil
reserves are in a fairly volatile area in the Middle East," he said on the
sidelines of a seminar on Biodiesel in Sao Paulo.
Brazil has a history of green fuel use. After the world oil crunch in the
early 1970s, it implemented its Pro-Alcohol Program to relieve the country's
reliance on foreign oil.
The programme also helps to stabilise sugar prices as the ethanol,
referred to locally as alcohol, is distilled from cane.
The country mixes its nationally sold gasoline with 20 to 24 percent
ethanol and also has a fleet of automobiles specially designed to run solely on
the cane-based fuel.
As soy-based biodiesel is not likely to be competitive with petroleum
diesel unless oil prices rise above $35 a barrel, Lovatelli said the success of
the programme in Brazil would depend on support from the government including
tax breaks and broader support on environmental grounds.
Agribusiness giant Archer Daniels Midland Co. said recently biofuels such
as ethanol and biodiesel should become key profit drivers over the next five
years and beyond as laws limiting pollutants in the United States and elsewhere
in the world grow stricter.
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