Sweet sorghum to ethanol
Nov 10, 2009 10:40 AM, By Elton Robinson, Farm Press Editorial Staff
The objective of the harvest and roller mill demonstration is to demonstrate that a biorefinery can be a feasible venture for entrepreneurial farmers and investors in the rural Mid-South.
The sweet sorghum experiment impressed German, who farms corn, cotton and soybeans in west Tennessee. “It amazed me how many gallons of juice can come off an acre, plus all that biomass.”
The trial will also examine production costs for sweet sorghum versus other energy crops.
“One of the things we like about sweet sorghum is that it’s a low input crop,” Powell said. “It uses around 60 pounds per acre of nitrogen. It’s also a drought-tolerant crop. We think it’s a good rotational crop for our farmers. Some of the other energy crops are perennials. With a perennial, a farmer has to make a decision on whether or not he wants to take three years to establish a stand.”
Currently, Mid-South producers don’t capture much value from corn’s conversion to ethanol — other than a higher commodity price — because of a lack of interest in building refineries south of the Mason-Dixon line.
The technology to convert biomass to ethanol could attract local biorefineries, but the technology — which requires the use of special enzymes — is at least five years away. That’s why sweet sorghum is considered “low-hanging fruit” for Mid-South entrepreneurs. No enzymes are needed, so the only thing holding it back is a well-designed factory and some entrepreneurial spirit.
Powell says the experiment in Whiteville “is to demonstrate the mechanized models, the high-volume commercial factories. There are people working on smaller models, mounting mills on old cotton pickers, but we’re trying to work this out on a true commercial scale, where you’d produce fuel to sell to the major oil companies.”
With a fully operational biorefinery, Powell figures the harvest and processing season will run about 120 days out of the year. The sweet sorghum has to be harvested prior to a hard freeze. “Once the ground freezes, you kill the plant and lose the sugar. When we do design a rural ethanol biorefinery, we’re going to need to run really hard during harvest season. Weather will be a factor.”
Spain says another experimental field of sweet sorghum was planted in west Tennessee behind winter wheat.
Sweet sorghum varieties being evaluated at the Whiteville operation include M81E, Topper 76 and Keller, noted Gong.
Another issue with on-farm fermentation is that the distillers yeast operates in a fairly narrow temperature range, Powell noted. “A factory is going to have to have the capability to adjust the juice temperature.”
e-mail: erobinson@farmpress.com
