Sunday, February 15, 2009
News, Science + Technology

Georgia’s sweet new biofuel

UGA blazes genetic path toward energy independence with sorghum

By Diane Loupe

Researchers and farmers are optimistic about the potential for sorghum, the source of syrup that Southerners have drizzled on their biscuits for generations, to produce biofuel. 

And that potential is likely to boom, since a team led by the University of Georgia has sequenced the genome of sorghum. Sorghum is only the second grain to be completely sequenced, after rice. Having a fully sequenced gene is a scientific coup, akin to having a Bulldog win the Heisman Trophy.

Sorghum now ranks a distant second behind corn as a source of fuel ethanol in the U.S. It has one leg up on corn, though: It’s much more drought-resistant. Making biofuel out of corn or sorghum is similar to the process that moonshiners use: The grains are allowed to ferment into alcohol, or ethanol. That method of producing biofuel uses only the seedheads.

But biofuel researchers and sorghum producers say another method of producing ethanol has greater potential. Instead of using just the seed, the cellulose-based method uses the entire plant. The stalks of sorghum, like sugar cane, contain a lot of sugar, another ingredient in cellulose-based ethanol production.

“By using the entire plant, you get a lot more fuel with less waste,” says Andrew Paterson, a distinguished UGA research professor who helped map the sorghum gene.

Paterson, director of the Plant Genome Mapping Laboratory, and his collaborators—some of whom come from as far away as India, Pakistan and Germany—mapped and analyzed the genome of Sorghum bicolor. Sorghum’s genetic code of 730 million bases, or letters of DNA, is a quarter the size of the human genome. The sorghum genetic study results appear in the Jan. 29 issue of Nature, a prestigious international science journal.

The technology for using the whole sorghum plant to produce ethanol is less mature than the seed-based technology used for corn, but sorghum advocates say the technology is developing.

In the U.S., sorghum is primarily used as livestock feed, although it can be consumed by humans—as it has been by Georgians for almost as long as there have been Georgians—and is a staple of peoples’ diet in sub-Saharan Africa, says Paterson. Sorghum’s potential as a fuel source prompted the U.S. Department of Energy's Joint Genome Institute to get involved with sorghum sequencing.

Sequencing the sorghum gene can help turn the grain into a “very robust biofuel” by helping scientists understand which genes control various characteristics of the plant, says Jeff Dahlberg, research director for the National Sorghum Producers (NSP), a trade organization based in Lubbock, Texas.

Researchers might be able to tinker with a gene to make the plant even more drought-tolerant, or to produce more cellulose.

“That’s a long way down the road,” admits Dahlberg. “But that’s one of the really exciting possibilities about the sequence: being able to tailor sorghum to meet biofuel needs.”

Corn dominates ethanol production because the industry started in the Corn Belt, says Dahlberg. But compared to corn, growing sorghum uses “less herbicide, less pesticide, less fertilizer and less water."

That’s good, but UGA’s Paterson can think of a substantial downside to seed-based biofuels like corn and sorghum: “They compete with the food supply," because both provide food for humans and for the livestock humans eat.

SUBHED: Sorghum is kinder to farmers

Georgia farmer Mike Bonner says he would welcome increased demand for sorghum if it translated to increased prices for the crop.

“The value of it is not as high as corn,” says Bonner, who farms 3,500 acres in Calhoun and Early counties in southwest Georgia. Sorghum typically fetches about 90 percent of the value of corn, although it’s “a little bit cheaper to grow.” Bonner plants about 200 to 300 acres of sorghum each year.

Although most Georgia sorghum is grown for feed, Bonner’s crops go to a niche market: plantation quail. Georgia plantations buy Bonner’s sorghum to spread it around to attract quail for hunters.

But higher demand for sorghum would help Bonner, because he could rotate sorghum with peanut and cotton crops.

“Oh yes, I would love to have a grass root crop for peanut rotation, rather than all this cotton I’m planting,” says Bonner. “If I could get a market for it, sure I would grow it. It’s a fairly easy crop to grow, and it’s fairly easy to harvest.”

As a grass, a crop of sorghum would break the life cycle of the nematodes that feed on peanuts and cotton, reducing the need to treat those crops with pesticides, he explains.

Also, sorghum’s roots go “so deep into the soil, that water filtrates better when you rotate with sorghum,” says Bonner.
Georgia uses a lot more corn than sorghum, says John McKissick, director of UGA’s Center for Agribusiness and Economic Development. That’s because Georgia uses a lot more grain to feed chickens and other livestock than farmers produce.
“Sorghum is a very good substitute for corn, but sorghum’s value is going to be controlled by corn,” says McKissick.

Paterson laments the fact that sorghum yields increased less than 1 percent per year over the last 45 years, only about half the rate of corn, rice and wheat yields, according to the United Nations Food and Agriculture Organization.

“Something is wrong with this picture,” he complains. “If new information and tools from the sequencing change that, it'll improve millions of people's lives.”

Dahlberg, at the NSP, thinks the problem might be solved by building more biomass plants.

“This is like the chicken and egg thing: Which came first?” he says. “We need a biomass conversion plant up and running before sorghum acreage will start increasing.” SP