By MATTHEW D. ERNST
HOPKINSVILLE, Ky. — Delta BioRenewables, a Memphis bioenergy firm, reported a successful 2012 evaluation of ethanol production from sweet sorghum at the Commonwealth Agri-Energy corn ethanol plant in Hopkinsville.
“We provided a 5,000-gallon tanker of sweet sorghum liquid sugar feedstock to Commonwealth Agri-Energy for evaluation in their system,” said Pete Nelson, Business Development director for Delta.
“Everything came off without a hitch,” said Mick Henderson, general manager of Commonwealth. “We wanted to see the sweet sorghum juice in a full truckload lot, run our own analytical profile and then introduce the juice in our fermentation system at full scale.
“The sugars in sweet sorghum were fermented in the same way as corn, without any significant changes to our process.”
Long grown in Kentucky for use in the region’s distinctive table syrup, sweet sorghum has generated interest as a biofuel crop because of its drought resistance and yield potential for marginal ground.
Sweet sorghum is on the pathway for acceptance by the U.S. Environmental Protection Agency as an advanced biofuel feedstock under the Renewable Fuel Standard. Grain sorghum was accepted as an advanced biofuel feedstock late last year (see related article).
Henderson said Commonwealth will continue to partner with Delta to use additional sweet sorghum for biofuel production in 2013. “I believe that our co-op could produce 5 percent or more of our overall annual ethanol production using sweet sorghum grown on nearby marginal land and under-utilized pasture,” he said.
The Commonwealth plant has the capacity to produce 33 million gallons of corn ethanol per year. Nelson said Delta plans to supply 20 tankers of liquid sugar feedstock to the Kentucky ethanol plant in 2013. This feedstock will come from the company’s own production, about 100 acres grown near Memphis, Tenn. That production supports development level projects in seven states focused on producing chemicals and biofuel from the crop.
The sweet sorghum hybrids used are Durasweet. Durasweet seed products are marketed under the Blade brand produced by Ceres, Inc., a biotechnology company headquartered in Thousand Oaks, Calif.
If the project’s success continues, said Nelson, there will be processing established at the Commonwealth facility and contract opportunities for sweet sorghum production on some of the region’s row crop farms. Such opportunities, he cautioned, will occur no sooner than 2015.
“Our company is very conservative when it comes to promoting new crop opportunities to farmers,” said Nelson. “There could eventually be long-term potential there for 2,500 to 5,000 acres of sweet sorghum in the Christian County (Hopkinsville) area, but there are still a lot of things to work out to make that a reality. Slowly, we’re picking up our production.”
High corn prices have sent ethanol producers examining alternative feedstock for existing ethanol plants. University research estimates that juice alone from an acre of sweet sorghum could produce between 530-700 gallons of ethanol, more than from an acre of corn.
“If starch and cellulosic ethanol are considered, sweet sorghum would likely produce between 50 and 100 percent more ethanol per acre than corn grain and stover,” reported University of Kentucky researchers in 2009. The bagasse co-product from sweet sorghum processing may be fed to livestock.
Randall Powell, chief technology officer at Delta BioRenewables, said sweet sorghum could help corn ethanol facilities diversify their feedstock supply, especially if the sweet sorghum is grown under contract.
“This successful trial proves the technical feasibility of integrating sweet sorghum sugars into existing corn ethanol facilities. It helps pave the way for other commercial projects,” he added.
The company’s biorefinery, which opened in 2009 just outside Memphis, provides sugar feedstock for food grade and industrial fermentation processing to the biofuel, renewable chemicals and food products industries. Delta processes sweet sorghum hybrids grown on its own research farm. Sorghum stalks are harvested, crushed and processed into a liquid sugar feedstock at the biorefinery.
The success of the project at Commonwealth Agri-Energy was lauded by national sorghum interests. “We see this significant commercial-scale trial as a catalyst for other corn ethanol facilities to consider diversification of their feedstock base,” said John Duff, director of Renewables for the United Sorghum Checkoff Program (USCP).
The sweet sorghum project in Tennessee and Kentucky was funded, in part, by the USCP. Early strategic planning support for the project was made possible through the partnership of Murray State University, West Kentucky AgBioworks, Memphis Bioworks Foundation, Kentucky Agriculture Development Fund, Kentucky Energy and Environment Cabinet and USDA Rural Development.