Marketing

Sweet sorghum has several potential uses. Those include biofuel, food and feed production. Traditionally, sweet sorghum has been used for food-grade syrup production. Converting sweet sorghum juice into syrup creates a product that has features similar to those of molasses, honey, corn syrup and maple syrup. Sorghum syrup production is most significant in Kentucky and Tennessee. To make sweet sorghum syrup, the National Sweet Sorghum Producers & Processors Association estimates that 25,000 acres to 30,000 acres are planted today.

Syrup production currently represents the most significant market for sweet sorghum. However, sweet sorghum has recently gained attention for its potential as a bioenergy crop. This guide describes using sweet sorghum juice or sap as a bioenergy source and its co-products for other purposes.

Sweet Sorghum Juice

Sweet sorghum stalks contain high-sugar juices. The juice’s sugar content may range from 12 percent to 23 percent. To extract the juice, equipment such as a roller mill or diffuser may be used. For sweet sorghum that’s harvested with a forage chopper, a screw press can extract juice from stalk material. Regardless of the extraction method used, targeted juice extraction rates should be at least 50 percent to perform best from an ethanol yield perspective.

After adding yeast, the sucrose, fructose and glucose sugars found in sweet sorghum juice ferment and create ethanol. For the yeast to work properly, the process requires a relatively consistent temperature. Following fermentation, about three-quarters of the product is alcohol. After distilling this solution to remove water, the final product concentrates to about 99 percent alcohol. Relative to other bioenergy feedstocks, such as corn starch, processing sweet sorghum juice into fuel requires fewer steps and inputs. For example, relative to processing corn starch into biofuel, the sweet sorghum juice conversion doesn’t need as many inputs, and the inputs needed are less expensive.

Additionally, compared with corn, sweet sorghum converts into ethanol more efficiently. Some research indicates that maximum corn ethanol production per acre would total 420 gallons, but ethanol production from sweet sorghum may range from 530 gallons to 700 gallons per acre. Energy yield from sweet sorghum ethanol may also be superior to that of corn ethanol. Based on USDA estimates, Btu production from corn ethanol would range from 1.3 to 1.8 for each fossil energy Btu invested in production. For sweet sorghum ethanol, Btu production may range from 12 to 16 for each Btu invested.

Because raw sweet sorghum juice has a short shelf life, juice extraction and fermentation must shortly follow harvest, and sweet sorghum production areas must be located near processors. The need for processing quickly after harvest, a relatively limited production timeframe and high central processing facility expenses have contributed to sweet sorghum gaining less regard as an ethanol resource compared with other feedstock material, such as corn. Another factor influencing opportunities to grow and market sweet sorghum as a biofuel feedstock involves the Renewable Fuel Standard. Greater opportunities for sweet sorghum-derived biofuel may develop if the Renewable Fuel Standard were to recognize sweet sorghum as an advanced biofuel feedstock.

Several firms have committed to the potential for using sweet sorghum juice as an ethanol feedstock. In 2012, Delta BioRenewables, LLC collaborated with Commonwealth Agri-Energy, LLC to use sweet sorghum sugars to produce ethanol at Commonwealth’s corn ethanol plant located in Hopkinsville, Ky. To use sweet sorghum sugar as an ethanol input instead of corn, the Commonwealth ethanol facility made no significant process changes. Efforts in west Tennessee, coordinated by firm BioDimensions, have also evaluated sweet sorghum as a biofuel crop.

In Florida, a few projects may expand sweet sorghum’s use as a biofuel feedstock. Southeast Renewable Fuels plans to operate a sweet sorghum ethanol facility near Clewiston beginning in 2015, and it will sell the facility’s ethanol production to Shell Oil Company. Within Florida, Southeast Renewable Fuels would eventually like to operate as many as three plants. A Highlands EnviroFuels facility capable of producing 20 million gallons of ethanol per year is a project planned by United States EnviroFuels, LLC. With annual capacity that could expand to 40 million gallons, the facility could use sweet sorghum or sugarcane as feedstock material, which the facility would plan to source from within 20 miles of the plant. In addition to the fuel produced, the facility plans to sell power to local electricity providers, produce beverage-grade liquid carbon dioxide and generate high-potassium fertilizer, according to the company’s website. The project has been planned for some time and has undergone changes in scope – for instance, the company has said that it may produce ethanol or another advanced biofuel – but the company still considers the project to be active. Initiatives in several other states, including Texas, Oklahoma and Iowa, have processed sweet sorghum for ethanol production.

In addition to their bioenergy potential, sweet sorghum sugars can be converted into bio-based chemicals. The chemicals may have application in plastics, rubbers, textiles and other materials.

Co-Products

Bagasse is the material that remains after extracting juice from sweet sorghum stalks. It has potential as a cellulosic ethanol feedstock. Cellulose produced from sweet sorghum has relatively low lignin content. The bagasse may be used as a power plant feedstock. Power plants may co-fire the bagasse as a combustible fuel much like they could use switchgrass or miscanthus. Burning bagasse will produce steam that can generate power and process heat. Additionally, the burning process may yield extra power to sell to a power provider. Bagasse can be formatted into pellets to burn for heat or electricity.

Although the bagasse has energy-related uses, it may also be a livestock feed ingredient. As a feed, sweet sorghum contains relatively low starch and protein levels, but it could be a readily available feed when weather hasn’t supported other crops. Bagasse could also be used as a mushroom-growing medium. Paper is another possible application for bagasse.

Vinasse includes the dead yeast and plant material that result from sweet sorghum fermentation. After being composted, vinasse has potential to be marketed as a fertilizer. Vinasse has an alternate use as a feedstock for anaerobic digestion and biogas production. Its chemical profile allows it to have biogas potential. Burning this biogas can lead to generating more electricity, which may be sold to the power grid.

If producers or processors don’t use bagasse or vinasse for energy, feed or composted fertilizer applications, then they may apply these co-products on fields to replace lost nutrients.

Depending on the variety, sweet sorghum plants may also produce grain. In a system similar to that for sugarcane production, no grain is preferred. However, small-scale producers may prefer varieties that yield grain. The grain may enable sweet sorghum to become a dual-product and -revenue crop. Producers could sell grain for food or feed use, or the grain could be used to produce ethanol.

Other Uses

Sweet sorghum sugars have been used for making hydrogen, butanol, lactic acid and acetone products. They’ve also had application in creating biodiesel production lipids. Other novel uses for sweet sorghum-derived ingredients include natural herbicides that leverage the crop’s alleopathic compounds, medicinal products and edible films and coatings for food.

While there are limited direct buyers of biomass crops, there are biomass power facilities located throughout the United States. These power plants require the biomass crops to produce energy. Below are both private companies, biomass power facilities, and biomass energy cooperatives that could be potential markets for biomass products.

The available markets presented on this website are meant to assist producers with marketing decisions. Please contact the specified business location prior to production of sweet sorghum to verify marketing capability.

Biomass Power Facilities

Biomass Energy Cooperatives

Sources

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Delta BioRenewables. 2012. Producing ethanol from sweet sorghum. Ag Annex. Simcoe, Ontario, Canada N3Y 4N5.

Delta Farm Press. 2009. Sweet sorghum to ethanol. Delta Farm Press.

Dweikat, Ismail. n.d. Sweet Sorghum Research. University of Nebraska-Lincoln. Lincoln, NE 68583-0915.

Greving, Bill. 2010. The Potential for Sweet Sorghum Biofuels. Ethanol Producer Magazine. Grand Forks, ND 58203.

National Sweet Sorghum Producers & Processors Association. 2014. National Sweet Sorghum Producers & Processors Association. Cookevile, TN 38503-1356.

Oklahoma State University. 2007. “Sweet” Biofuels Research Goes Down On The Farm. ScienceDaily. Stillwater, OK 74074.

Pfeiffer, Todd, Michael Montross and Michael Barrett. 2013. Sweet Sorghum for Biofuel. University of Kentucky Cooperative Extension Service. Lexington, KY 40546-0091.Poligrafiche San Marco S.a.s. 2011. Diffusion of a

Sustainable EU model to produce 1st generation ethanol from sweet sorghum in decentralized plants. SWEETHANOL Sustainable Ethanol for EU. Cormons (Gorizia) Italy.

Rooney, Lloyd W. 2013. Sorghum as a Bioenergy Feedstock. Sweet Sorghum Ethanol Association. 2013 Annual Conference.

Stevens, Gene. 2019. Sweet Sorghum for Biofuel Production. eXtension.

Sorghum Checkoff. n.d. A Sweet Deal for Ethanol. United Sorghum Checkoff. Lubbock, TX 79403.

United States EnviroFuels, LLC. 2015. Projects. United States EnviroFuels, LLC. Riverview, FL 33569.

Valero, Marc. 2014. After false start, biofuels industry may yet impact Highlands County. Highlands Today. Tampa, FL 33606.

Veal, Matthew W., Mari S. Chinn, Matthew B. Whitfield. 2014. Sweet Sorghum Production to Support Energy and Industrial Products. North Carolina Cooperative Extension. Raleigh, NC 27695.

Vermerris, Wilfred, John Erickson, David Wright, Yoana Newman and Curtis Rainbolt. 2011. Production of Biofuel Crops in Florida: Sweet Sorghum. University of Florida IFAS Extension. Gainesville, FL 32611.