Gevo restarts isobutanol production at Luverne: what’s happening now, what happened?

June 18, 2013 |

A bacterium with a sweet tooth


Let’s look at the 2012 problem – what it was, what it wasn’t. At the end of the day, the problem at Luverne came down to this guy and friends of his — strains of bacillus, a rod-shaped, single-celled bacteria with an insatiable appetite for dextrose, or corn sugars.

Microbial infections are a common feature of world-scale fermentation — especially in their commissioning period — they’re a common nuisance with ethanol plants, also, that have developed antibiotics and other strategies to combat them.

As Gevo CEO Pat Gruber observed, in talking with the Digest, “First step was, for us, to make sure we understood all the competitors that are chewing up the sugar, eating up yield. There’s no way to know until you do it, at scale. What matters is how you respond.”

Bacteria lurk. Picture the small white infection spots you see on a child’s inflamed tonsil when tonsillitis or strep throat strikes — and parents will know that those type of infections can go away and then suddenly strike again. Those are lurking bacteria that have found a happy home, hung up in a tube somewhere inside the body — lying in wait for the right conditions to appear, and then spring back into view.

It is not completely different with microbial contamination in fermentation systems — likewise, the microbes embed themselves in small infection pockets, and then rise up in numbers when the sugars start to flow.

“You are always going to have microbes, whether they come in through the air or water,” said Gruber. “But there is ‘manageable’, and then there is ‘outnumbered’.

In Gevo’s case — given that this is a new system, producing isobutanol instead of ethanol, it was essential to understand the particular cocktail of microbes before designing a remedy. “The fixes included changing the fermentation conditions and related operating parameters,” noted Gruber, “making equipment modifications to improve sanitization, and, most importantly, improving our operating discipline—the procedures we use at the plant.

In today’s Digest, we look at how the responsible microbes were isolated and conquered, the role of the 2012 drought in Gevo’s timeline, the path to full production, the Redfield project and other opportunities for expansion, the Gevo-Butamax dispute, and the bottom line, via the page links below.

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