Ethanol From Citrus Peels

WASHINGTON - Apr 6/06 - SNS -- USDA researchers are working on the economic feasibility of producing ethanol from citrus peel waste.

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.

Starting in 1992, researchers at the Agricultural Research Service (ARS) Citrus and Subtropical Products Laboratory in Winter Haven, Florida have been looking at producing ethanol from the peels. Low gasoline costs kept interest in the concept at a low ebb

The changed in 2004. Bill Widmer, an ARS chemist at Winter Haven, 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. His project was partly funded by Renewable Spirits LLC of Delray Beach.

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.