NCERC successfully produces cellulosic ethanol from corn fiber

By Holly Jessen | May 15, 2012

The National Corn-to-Ethanol-Research Center recently reached a milestone with the successful production of cellulosic ethanol from corn fiber or corn bran. It’s part of ongoing research to make second-generation ethanol a reality. “We want to take the mystery out of cellulosic ethanol,” said Sabrina Trupia, assistant director of biological research for NCERC.

The methods used to achieve cellulosic ethanol fermentation should—in theory—be feedstock neutral, said NCERC Director John Caupert, In other words, the information, which will be part of the public domain, can be used for more than just corn fiber. “If we can apply it to this, we can apply it to many others,” he said, naming switchgrass and miscanthus as examples of other potential feedstocks the fermentation technology could possibly successfully ferment. 

On the other hand, Caupert considers corn fiber the feedstock with the broadest potential commercial application. After all, he said, there are already more than 200 corn-to-ethanol plants across the U.S. successfully handling corn fiber daily. Although not every corn ethanol plant could or would eventually add bolt-on cellulosic ethanol technology, it is the most common form of cellulose available to ethanol producers, he said, adding that he believes it’s also the most commonly forgotten form of cellulose.

NCERC’s research into cellulosic ethanol production from corn fiber was made possible due to a series of actions, grants and capital gifts. That includes a $225,000 grant through the Illinois Department of Commerce and Economic Opportunity as well as equipment donations. Specifically, NCERC utilized a dry corn fractionation system donated by Cereal Process Technologies LLC in 2010 and a fermentation suite donated by an anonymous individual in 2011. The used fermentation equipment was manufactured and refurbished by ABEC Inc., a company which operates a stainless technology division out of Springfield, Mo. Once work on the fermentation suite is completed it will be made up of two 20-liter fermentation vessels, at least one 30-liter vessel, two 150-liter vessels and two 1,500-liter vessels, Caupert said. Only the 30-liter vessel is not ABEC technology and was purchased by NCERC from another vendor.

It’s also important to note that everything used to produce the cellulosic ethanol at NCERC is already public knowledge. “It’s all readily available commercially marketed technologies,” he said.

In this round of research NCERC used a 30 liter fermentor to produce cellulosic ethanol, Trupia said. NCERC focused on fermenting the cellulose, not the more difficult-to-ferment xylose or C5 sugars. The next step is to obtain more funding and look deeper into the fermentation process and the yeasts used.

Beginning this summer, researchers will begin to assess the performance of modified yeast NCERC received from the USDA and has evolved with one of its collaborators, Florida-based Biotork. One of the challenges of corn fiber as a cellulosic ethanol feedstock is that is contains more hemicellulose, which contains C5 sugars, than it does cellulose, Trupia said. Though the first phase, fermenting cellulose, wasn’t exactly easy, the next step is going to be much more difficult.

Trupia will talk about this research on June 5 at the International Fuel Ethanol Workshop & Expo as part of a panel presentation on “Leveraging Pretreatment and Process Pathways to bring Second Generation Biofuels Capability to First Generation Producers.”