One man's gin trash is — another mans fuel supply? Could be, if a research project currently under way at the USDA-ARS station in Lubbock, Texas, ignites enough consumer interest to make pelletized gin trash competitive with similar fuels.
Research also explores potential for gin trash as mulch/fertilizer, livestock food or building material.
USDA engineer Greg Holt says the study began in response to a cotton gin survey that indicated gin trash disposal as the number two problem facing gin managers, behind air quality permitting. Partial funding comes from Cotton Incorporated.
“Our challenge was to change the product,” Holt says. Trash has negative connotations, conjuring up images of tin cans, plastic containers and dirty diapers.
“This is not your typical trash,” he says. “It consists of residue from plants, seed, twigs and sand. We call it trash and ginners have attempted a number of ways to find a use for it.”
Holt says the result should be similar to turning iron ore into steel. “It becomes something entirely different when it's processed.”
Processing includes cooking, grinding, and sterilizing the gin residue. “We cook it at 240 degrees Fahrenheit to get rid of weed seed and fungus,” he says. Processed, the product resembles a bag of finely ground garden mulch instead of coarse bits and pieces of lint, leaves, stems, burrs and other field debris.
The new product becomes a different raw material, which further processing can turn into a handful of manufactured goods.
“We can determine what product we want depending on price,” Holt says. “That's the advantage of having material that converts into more than one end use.
“With just one market, the buyer sets the price; with multiple markets, the seller has an advantage.”
The process, tabbed COBY for cotton by product, includes adding a starch to the raw material. Then a manufacturer can turn it into pellets for fuel, livestock feed, a mulch that can be augmented with other nutrients or compressed into a building material.
Holt says processing gin trash improves animal digestibility by 25 percent, based on lamb feeding trials. “Texas Tech researchers are conducting other tests on heifers.”
Feed products may offer the most familiar market. “It's already an acceptable raw material in the livestock feed market. But we have to change the mindset so feeders view this as a more valuable product than the raw material.”
Although the feed market may be the most obvious, it holds less promise than other uses, Holt says. “Any feed product in this area always will compete with alfalfa hay. Alfalfa sets the standard.”
Fuel use offers more and could be the most promising possibility early on. “U.S. consumers used more than 730,000 tons of pellet fuels last year,” he says. “The market already exists.”
Pellets burn in specially designed “wood” stoves, which traditionally use pellets from lumber waste. The gin residue pellets produce a heat value equal to the wood products and could be priced lower.
Currently, wood pellets sell for $140 a ton. Holt says the gin residue pellets burn cleanly, with no odor “after they're ignited. We'll continue to test stoves for heating values and emissions.”
He says fertilizer/mulch initially may be a niche market. “But this could be a sleeping giant. Landscapers like the way it looks and they can add potassium, phosphorus and nitrogen to it. We have to verify that we can remove weed seed and chemical residue from the product.
“I'm really excited about the building material potential,” he says. “We're still trying to determine potential for flaking, peeling and the long-term effects of the sun. We want to do flammability tests to see if it will withstand temperatures up to 1,400 degrees Fahrenheit without deformation.”
Potential uses include decking material, railroad ties and cinder blocks. “The material takes screws or nails without flaking,” he says. “It's lightweight but strong.”
Holt says gin residue products also offer environmental advantages. “It's an annually renewable resource.”
To make gin residue products viable, someone will have to build processing plants, Holt says. “People are looking at building manufacturing facilities, but they need an idea of the market potential. We know the pellet fuel market is established. And companies in Illinois and Arizona expressed interest in the fertilizer/mulch.”
He says processing plants may offer farmers opportunities to form cooperatives and keep profits from the value-added products in the communities where they produce the raw material.
In the meantime, Holt says research will continue testing the materials to “see what we need to change to provide products that companies want.”