Cropping Up

Delta BioRenewables reaches milestone in sorghum production

By Bill Dries

Earlier this month, workers at the Delta BioRenewables plant at Agricenter International loaded a commercial-sized batch of the processed sugar juice from crushed sweet sorghum stalks into a commercial tanker truck.

Jeffrey Sundling prepares sorghum samples at the research and pilot production facility for Delta BioRenewables, which is operating one of the first commercial-scale processing facilities in the United States.  

(Photos: Lance Murphey)

The truck traveled from Memphis to the Commonwealth Agri-Energy corn ethanol plant in Hopkinsville, Ky. – a road trip that marked an important milestone at the end of a busy year for Delta BioRenewables, a Memphis producer of sustainable feedstock that is developing various bioenergy products.

The same machinery used in Hopkinsville to make ethanol from corn was used to make ethanol from sweet sorghum and the Kentucky plant is part of a 15-billion gallon a year corn ethanol industry with an existing infrastructure across the country.

The juice from the sorghum stalks has a number of uses depending on how it is fermented and distilled. Using it as a substitute for corn ethanol is just one end use among many, said Pete Nelson, cofounder of BioDimensions and business development director.

The Memphis company isn’t trying to replace corn but supplement it.

“It’s a drought tolerant crop,” Nelson said. “It uses less nitrogen than corn. We’re not looking to replace any commodity crop. We just want to add other options to farmers. We think in areas that don’t have good irrigation or other reasons that the sorghum would be a good rotation crop.”

In Hopkinsville, Commonwealth Agri-Energy general manager Mick Henderson estimated the 2,300-member farmer co-op there could use sweet sorghum for approximately 5 percent of its overall annual ethanol production.

“The sugars in sweet sorghum were fermented in the same way as corn, without any significant changes to our process,” Henderson said. “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 test was important because it shows the raw material can be used across several platforms and for different uses. The juices change rapidly over time as they ferment.

“It’s pretty perishable,” Nelson said. “We are working on two ranges of customers. Some are the large industrial scale where we’re integrating directly into their facility.”

Those larger facilities store corn year round. Sorghum wouldn’t be stored but would be processed using the same machinery three or four months a year and grown nearby.

Jared Lindley pours a sample of sweet sorghum juice in the lab at Delta BioRenewables. DBR is operating one of the first commercial-scale processing facilities for sweet sorghum in the United States. 

Agricenter is one end of a pipeline that includes research in sorghum hybrids.

“Corn was at about 30 or 40 bushels an acre in 1940 and because of all of the innovation with hybrids and breeding, we’re at about 250 to 300 bushels as the high now,” Nelson said. “We’re just starting to do that with sweet sorghum where major companies are investing tin the sweet sorghum genetics and the breeding. We’re going to see a huge ramp up in terms of the yields and the capabilities with sorghum. A lot of that work we are doing here in Memphis will feed into the satellite sites across the Southeast.”

This year Delta BioRenewables became a stand-alone company with Memphis Bioworks, Epic Biofuels and Willie German of German Farms in Whiteville among the partners.

German drew sorghum test crops for several years on his land and allowed the use of a cotton gin there for a small biorefinery. The Whiteville effort led to this year’s relocation to Agricenter.

“As it scales up there will be large-scale processing in conjunction with those end users. One of those will probably be in the Memphis area … feeding a Memphis customer,” Nelson said. “One will be in Hopkinsville. We actually have candidates in seven states that we are sampling out of Memphis.”

The sweet sorghum process borrows heavily from Florida’s sugar cane industry in terms of infrastructure and BioDimensions grew its crops for several years in rural West Tennessee using a nearby cotton gin as the processing center.

“It’s really been growing down in Brazil where they already have a sugar cane industry and they’ve got billions of dollars of capital assets already invested in sugar cane,” Nelson said. “They are adding sweet sorghum as an offseason crop using the same infrastructure.”

Meanwhile, BioDimensions Inc. is an investor in Infinite Enzymes LLC of Jonesboro, Ark., which this month made available commercially a single activity plant based cellulose enzyme to be used in sustainable manufacturing, including the processing of recycled paper. The enzyme is available for research and development projects.