Citrus Peel Waste a Potential Source of Ethanol
AEN News
Washington - Thanks to recent hikes in gasoline prices, there is
a renewed interest in finding a cheaper way to fill up the gas
tank. Researchers at the Agricultural Research Service (ARS)
Citrus and Subtropical Products Laboratory in Winter Haven,
Fla. have been working on a potential substitute: citrus peels.
In 1992, Karel Grohmann, then research leader of the Winter
Haven lab, began researching the feasibility of converting
citrus peel waste into fuel ethanol. Citrus waste materials
are rich in pectin, cellulose and hemicellusic polysaccharides,
which can be hydrolyzed into sugars and fermented into alcohol.
Most of this dried peel residue--a total of 1.2 million
tons annually in Florida alone--is currently marketed as
low-value cattle feed, despite its relatively high
processing cost.
In 2004, Bill Widmer, an ARS chemist at Winter Haven, picked up
where Grohmann left off, with the help of a cooperative research
and development agreement partner, Renewable Spirits LLC of
Delray Beach, Fla. Widmer and his scientific team first
modified the process to substantially reduce the amount of
enzyme required to convert the citrus waste carbohydrates
to sugars and ethanol. Now the process shows economic
promise for large-volume production.
Beginning with the one-quart-to-one-gallon laboratory process
developed by Grohmann, the process was modified to work at 10-gallon,
100-gallon and 1,000-gallon batch levels. A 10,000-gallon pilot
facility is currently under construction, and should be finished
by sometime this year. With further research, according to
Widmer, Florida's citrus peel waste could yield up to 80 million
gallons of ethanol per year.
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