Wood pellets are big business as an export item. Europe consumes much of the U.S. wood pellet market to generate energy according to the USDA Foreign Agricultural Service. In fact, in 2018, the combined value of sales from the U.S. exports of wood pellets totaled $812 million or 6.04 million metric tons with transfers to the U.K. topping $646 million or 4.71 million metric tons. Since much of the pellet production in the U.S. comes from southern yellow pine in the Southeast, researchers in the Forest and Wildlife Research Center are studying ways to make a better, stronger wood pellet out of southern yellow pine.
Dr. Jason Street, assistant professor in the Department of Sustainable Bioproducts, and researcher in the Forest and Wildlife Center, is fnding ways to improve wood pellet strength, durability, and water resistance. His team is evaluating hardwood, planer shavings, additives, and storage air-fow to improve the properties of southern yellow pine energy pellets.
"Essentially our goal has been to use particular additives to improve wood pellet characteristics while also lowering the power consumption required to produce southern pine energy pellets. We produce the pellets on an industrial scale and then test the performance of each additive according to the pellet's energ y content, bulk density, moisture content, ash content, and durability," Street said.
Street said the research will help discover uses of byproducts from lumber mills to make an existing product better.
"One question I am constantly asked is how to get rid of all the residuals found at sawmills. We are attempting to improve the quality of wood pellets using materials that are currently thought of as waste and we have had successful trials already using various concentrations of these materials in the pelleting process," he said.
The three-year project, now in its second year, sought to investigate how different additives effected the performance and characteristics of southern yellow pine pellets. They tested southern yellow pine derived biochar and bio-oil as well as cornstarch, vegetable oil, sweet potatoes, microcrystalline cellulose, micronized rubber powder, and mixed hardwood planner shavings to see how each additive impacted pellet durability, bulk density, and higher heating value. They also conducted an economic feasibility study to determine if the additives could increase proft of the mill compared to the controls. They found that certain additives used for pellet production showed the potential to improve the overall properties of the wood biomass pellets while improving profts. These additives included hardwood planer shavings, biochar, micronized rubber powder, and bio-oil.
The team is continuing to home in on the best methodology.
"Many of the materials now considered waste can be used in pelleting if it's not dragged through the dirt or mud. Byproducts can also be upgraded to a bio-oil or biochar, which when added to the pelleting process improves the durability and energy content of the product," he said.
He hopes to continue to fnd ways to use limited-value materials while helping pellet manufacturers make more money.
"We are continuing to make improvements to southern yellow pine pellets while also lowering production costs with just a small percentage of renewable additives. We hope that this will eventually lead to an increased market demand on materials that are currently thought of as by-products. Utilizing as much of the wood product as possible can potentially lead landowners to be able to recover more revenue in timber production," Street said.