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OK Researchers Studying Sweet Sorghum in Production of Ethanol

Posted on: Monday, 20 March 2006, 21:00 CST

By David Page

Researchers at the Food & Agricultural Products Center at Oklahoma State University are studying the feasibility of using sorghum as an additive in the production of ethanol.

Sweet sorghum has the potential to be used as a renewable energy crop and has become a viable candidate for ethanol production, said Danielle Bellmer, food processing engineer at the center in Stillwater.

The process being investigated at OSU could result in increased sorghum production in Oklahoma.

Right now we are not growing much sorghum but we can, Bellmer said.

Sorghum has some sweet advantages as an additive for petroleum-based fuels but also has disadvantages, said Bellmer, the principal investigator for the project.

Using starch crops for ethanol requires using heat processing to convert the starch into simple sugars. Sweet sorghum is exempt from complex processing because the simple sugars are directly juiced from the stalks - eliminating starch conversion and creating an advantage over other starch crops.

Ethanol is an alcohol-based alternative fuel produced by fermenting and distilling simple sugars, mostly from starch crops such as corn.

Corn is widely used as an ethanol additive.

A $71 million ethanol plant will be built in Enid with production expected to start in February 2007. It will be the first commercial ethanol production facility in Oklahoma. The plant will use corn and milo.

The ethanol plant is being built by a joint venture including the Oklahoma Farmers Union Sustainable Energy LLC, known as OK Fuse, and Chaparral Energy, a private, independent oil and gas producer and operator based in Oklahoma City.

Sweet sorghum is not as popular as corn as a source of ethanol because of high costs associated with constructing and operating a central processing plant, Bellmer said.

Building a central processing plant for sorghum might not be feasible because there is not a good way to store sorghum so you have to process it as you harvest it, Bellmer said.

While starch can be stored for long periods of time, the simple sugars directly derived from sweet sorghum have to be fermented immediately, she said.

The harvest season for sweet sorghum is only a few months, Bellmer said.

Since the sorghum juice cannot be easily stored, the processing plant would only be in production for only a few months out of the year, making it economically unfeasible, Bellmer said.

A man from Iowa has a possible solution to the sorghum storage problem. The OSU research project started after Lee McClune, president of Sorganol Production Co. of Knoxvlle, Iowa, asked the OSU Food and Agricultural Products Center for some help.

McClune's solution is in-field ethanol production in which sorghum juice will be collected, fermented and distilled in the field - eliminating the need for a central processing plant, Bellmer said.

Her goal is to determine the validity and economic feasibility of McClune's solution.

McClune developed equipment to harvest and press sweet sorghum into juice in a single pass through the field. The harvester has the potential to produce 4,000 to 6,000 gallons of juice per acre, he said.

Fermentation, which must begin immediately after harvesting, is another problem.

The Food and Agricultural Products Center is researching the hypothesis that fermentation can take place in large storage containers in the field.

The idea of using sweet sorghum to produce ethanol is not new. A similar crop, sugar cane, is being used in Brazil to product ethanol.

At a distillery in Sao Tome, Brazil, 92,500 gallons of ethanol are produced daily using sugar cane during the March-to-November harvest season, according to a report from Associated Press.

The ethanol is delivered by trucks for immediate sale at the pumps in Brazil, where ethanol is used to fuel seven of every 10 cars.

Source: Journal Record - Oklahoma City

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