Turning Plants into Butanol at the Audubon Sugar Institute

Nov 9, 2015

A diluted combination of sweet sorghum, energycane, and sugarcane syrups sits in the jug on the left. It's slowly but continuously pumped through a column packed with teeny, bacteria-covered ceramic beads. By the time it makes its way to the jug on the right, the bacteria have fermented it into a mixture of butanol and isopropanol.
Credit Travis Lux

Ethanol is by far the most commonly produced biofuel in the country. But it has some problems. For one, its only about two-thirds as efficient as gasoline.

“Secondly,” says Dr. Donal Day, “ethanol has a serious problem in that it likes to pick up water. Why is that a problem? You cannot move ethanol in a pipeline because it’ll cause corrosion.”

Day is a researcher at the LSU AgCenter’s Audubon Sugar Institute, where researchers are trying to find ways to produce biofuels and bioproducts from the sugars found in Louisiana plants – like sweet sorghum and energycane.

“We wanted a better fuel than ethanol,” he says, “That took us to butanol.”

Day says that producing butanol by fermenting sugary plant juices isn’t new. But what is new is the way he and his team are producing it. The first big difference is in the bacteria they use to do the fermenting.

“There are microorganisms out there that’ll do anything you want if you have the right ones,” says Day.

They get their bacteria from Optinol – a biofuel company they’ve been collaborating with. This special, patented bacteria produces a higher percentage of butanol.

“So that simplifies what we wanna do.”

They’ve also simplified the fermentation process itself. Typically, biofuels are fermented in batches. You fill a container up with sugary liquid, add your bacteria, let it ferment. Then you drain away the product and repeat. But Day’s team has perfected a method of continuous fermentation, which by itself increases efficiency five-fold. Day says that even though low oil prices are driving down the demand for biofuels, he’s optimistic about butanol’s future.

“It is a promising thing,” he says. “We are at the point to scale it up. I would say the next stage is demonstration plants, and then commercial.”