The battle between Butamax™ and Gevo over isobutanol technology continues.

Last week, Gevo received a landmark patent from the United States Patent and Trademark Office for its GIFT(R) separation unit, a central part of the company’s fermentation technology for the production of isobutanol. The patent, “Recovery of Higher Alcohols From Dilute Aqueous Solutions,” addresses the separation technology used to produce propanols, butanols, pentanols, and hexanols, and also address how ethanol plants can be retrofitted to produce higher alcohols.

At the same time, Gevo also filed a lawsuit against Butamax™ Advanced Biofuels and DuPont charging that those companies infringe the newly issued patent. Gevo contends that Butamax and DuPont “perform the methods described” in the patent without Gevo’s authorization and should pay unspecified damages after a jury trial.

Today Butamax™ officials called the lawsuit allegations “unfounded.”

“Let us state emphatically, Butamax does not infringe the generic product separation technology claims in Gevo’s recent patent, which is already subject to a validity challenge by a Brazilian inventor,” declared Paul Beckwith, Butamax™ CEO. “While it does not surprise us that questions are being raised as to the validity of Gevo’s latest patent and whether Gevo provided sufficient disclosure in their patent application, Butamax does not use this technology.” Butamax has filed a motion to dismiss Gevo’s previous case against Butamax, and also will pursue early resolution of this latest suit.

Butamax officials claim that because vacuum flash fermentation technology was found to require high energy and water consumption to meet commercial productivity, Butamax developed fundamentally different product recovery systems. “The Butamax™ approach combines energy integration, reduced environmental impact and attractive production metrics. Butamax™ technology is covered by the 7,993,889 patent which is the subject of the Butamax™ lawsuit against Gevo for their unlawful infringement. This patent has significant priority over all of Gevo’s patent filings.”

The battle between the two companies goes back over a year ago to when Butamax was first awarded its patent in December 2010 and filed suit for infringement against Gevo in January 2011.