Agricultural engineer Greg Holt
(left) and engineering aid
Clint Sanders compare cotton
gin byproducts before and after
the COBY process.
ARS scientists in Lubbock, Texas, warmed
up beside pellet stoves burning cotton.
Well, they were actually burning pellets made of cotton-gin waste in two
commercial pellet stoves near their experimental cotton gin. They wanted to see
whether pellets made from gin trash burn at least as well, and as cleanly, as
typical pellets made from sawdust and wood chips or wheat straw.
"The pellets do burn as well, but as to the cleanliness, evaluation of
the data is under way," says ARS agricultural engineer Gregory A. Holt.
Gin trash comprises the parts of cotton plantsstems, leaves, and
bursthat are removed during ginning, which leaves the separated cotton
fibers and seeds as clean as possible.
Adding a little cottonseed oil to the pellets increased the heating value of
the fuel to about 9,000 BTUs per pound of pelletshigher than most wood
Sanders (left) and Holt
evaluate eight different
pellet fuels for efficiency,
pollutant emissions, and
ease of handling.
"The pellets leave more ash than wood, but the ash is the loose form
that can be easily dumped from the stove's ash collector," says Holt.
Aladdin Hearth Products of Colville, Washington, lent the two stoves for the
The ARS scientists have devised a new low-cost way to add value to cotton
wastea patented system known as the COBY (Cotton Byproducts) process. It
uses a hot, gelatinized starch solution that acts as a glue to hold the cotton
waste ingredients together and a lubricant to smooth the mixture's flow through
the extrusion equipment. The procedure cooks, sterilizes, and improves nutrient
availability in the mixture, which can be formed into pellets for various uses.
Holt and colleagues in Lubbock's cotton country burned three types of
pellets made by the COBY system using waste from ARS gins in Lubbock as well as
in Stoneville, Mississippi. The pellets contained a low-starch mix, a
high-starch mix, or a low-starch/low-cottonseed oil blend. "Gin waste can
have a different makeup depending on the cotton-growing areas. Some have more
woody material, like plant stems. We are studying how that affects their
heating efficiency," Holt says.
In a cotton gin, Sanders
(left) and Holt examine
extruded cotton gin waste
before it is made into
pellets for use as feed,
fuel, or fertilizer.
The pelletizing is done using a
commercially available pellet mill at the researchers' facility. The pellet
mill presses the cotton-gin trash and other ingredients into pellets that are
about 1/4 inch wide and 1/2 to 1 inch long.
According to the Pellet Fuels Institute, 57 firms reported making bagged
pellet fuel, with sales of 730,000 tons during the 2000-2001 heating season, a
14-percent increase over the previous season. All the pellets are made with
biomass materialsthe products of commonly grown plants and trees. Pellets
made for residential use can be bought at stove dealers, nurseries, building
supply stores, and feed and garden supply stores nationwide.
Holt wants to see whether cotton waste can make better pellets for feed and
fuel If he's successful, the nation's 2.5 million tons of cotton gin waste
would be more useful. He says the COBY system is very flexible, since it is
easy to add and thoroughly mix extra ingredients as desired, such as cottonseed
oil for fuel pellets, nitrogen for fertilizer pellets, or protein for feed
"The process cooks and blends several different ingredients together,
so you can easily tailor-make products," Holt says. "We can add
things like molasses, cottonseed, various grain meals, and protein supplements
in making feed pellets."
Holt is looking for new uses for cotton waste, such as a loose,
nonpelletized mulch for flower beds. Such uses could bring a higher price and a
more consistent use of cotton byproducts.
"By creating value-added products," Holt says, "we improve
the marketability of cotton byproducts, turning them from waste into a
commodity that can raise ginning income and potentially create jobs in rural
Cooking the starch solution and added ingredients has the added bonus of
killing any weed seeds or fungi that might be in the cotton waste, making it
safe as a fertilizer or mulch. Holt and colleaguestogether with
Illinois-based Summit Seed, Inc.are testing the cotton-byproducts mulch
on flower beds in Illinois, at a local university's test facility. The seed
company is interested in working with ARS to commercialize the mulch and
Insta-Pro International, a division of Triple "F," Inc., of Des
Moines, Iowa, a manufacturer and marketer of extrusion equipment and
technologies, supplied the Lubbock researchers with an extruder to begin the
COBY testing. USDA has granted Insta-Pro an exclusive license to either process
COBY or issue a sublicense to other companies. Insta-Pro's marketing strategy
is to offer cotton gins the opportunity to purchase the system to process COBY
products, along with granting the gins a sublicense agreement for the
manufacture and marketing of COBY products.
Holt says several cotton gins are currently considering coming together to
build a plant to process and sell their own waste.
In February 2002, the researchers started a 62-day feeding trial of COBY
feed made at a local producer's facility. The trial is being done with 100 to
120 heifers at a feedlot at Texas Tech University in Lubbock. They are testing
various mixtures, including one with a commercial protein supplement added.
Earlier tests showed the extruded COBY product made the feed more digestible
than commonly used cottonseed hulls.
Cotton Incorporated of Raleigh, North Carolina, helps fund the research and
development for all the trials of the various uses for cotton waste processed
with COBY.By Don
Comis, Agricultural Research Service Information Staff.
This research is part of Quality and Utilization of Agricultural Products
(#306), an ARS National Program described on the World Wide Web at
Gregory A. Holt is with the
USDA-ARS Cropping Systems
Laboratory, P.O. Box 215, Lubbock, TX 79401; phone (806) 746-5353, ext.
226, fax (806) 744-4402.