Corn Ethanol 1.5

The idea of cellulosic ethanol from corn bran or fiber has been around for more than a decade with little progress. Is that about to change?
By Holly Jessen | October 05, 2012

John Caupert, director of the National Corn-to-Ethanol-Research Center, is passionate about the subject of corn bran to cellulosic ethanol. He believes it’s not too strong to say that if first-generation ethanol producers want to stay competitive within their own balance sheets, they must be considering commercially available bolt-on cellulosic ethanol technologies today. “We’re very, very excited about this work, and we think the entire industry will be very soon,” he tells Ethanol Producer Magazine, hitting the table for extra emphasis.

NCERC announced it had successfully produced cellulosic ethanol from fractionated corn bran in May. In September, researchers embarked on a project to ferment corn flour, while paying special attention to the corn fiber to improve ethanol yield, says Sabrina Trupia, assistant director of biological research for NCERC. As of the week of Sept. 17, researchers had scaled up to 150 liter fermentations. Another sign of progress is Quad County Corn Processors’ plans to add bolt-on cellulosic ethanol technology to its corn-ethanol facility. (See the story on page 30 for more details.)

The National Renewable Energy Laboratory completed several cooperative projects in this arena in the 1990s and early 2000s, says Andy Aden, a former senior research engineer at NREL. One study published in 2004 concluded that fermenting additional alcohol from distillers grains was readily accomplished, showed promising results in an animal feed trial and came with a two-year payback period. Another one laid out the results of fermenting “quick fiber,” produced in a modified milling process developed by the University of Illinois. Despite these and multiple other projects targeting wet mill and dry mill ethanol plants, the concept didn’t get a lot of traction, Aden says. Recent signs show that trend may be changing, however. “It will be interesting to see if it continues to gain momentum,” he says. “I’m excited that there are still people looking at this and there are companies working to make it happen.”

In the months following NCERC’s announcement on corn bran-to-cellulosic ethanol, Caulpert has met repeatedly with officials from the White House, the USDA and various trade and commodity groups, he says. But he’s also heard from people who have a been-there-done-that attitude about corn bran cellulosic ethanol. The difference is that in times of cheap corn ethanol producers didn’t have the drive or the necessity to become as proficient and efficient as possible. “$8 corn turned that on its ear,” he says, adding that the push to waive the renewable fuel standard is also playing a part. That’s why he feels strongly that the existing grain-based ethanol industry will have an important place in the advancement to cellulosic ethanol. “The quickest way to get there is through the adoption of commercially available bolt-on types of technologies,” he says.

The beauty of corn bran is that it doesn’t require any special collection methods, transportation or storage, he adds. Other cellulosic feedstocks, including agricultural waste, require all of those, plus a lot of money. That’s why corn bran is the logical starting place. “I believe it will be a niche,” he says, “a niche that will launch us into a wide variety of different cellulosic feedstocks.” Trupia agrees. She sees corn bran as ethanol’s 1.5 generation, a transition point from the more than 200 grain-based ethanol plants in the U.S. to greenfield plants converting crop waste, forest residue and other nonstarch feedstocks.

That’s why the work on corn bran cellulosic ethanol at NCERC is so important, Caulpert says. For one thing, the information will be publically available. “What excites us about that is the fact that anybody and everybody in the industry from coast to coast and border to border can utilize that information,” he says. “If it sounds like I am overemphasizing that point, it’s because I feel we can’t overemphasize that point.” Time and funding support for the idea are both of the essence, “so 36 months from now we’re not sitting here having the exact same conversation that we are having today,” he says.

Corn bran is a good incremental step to cellulosic ethanol from nonfood feedstocks, Aden agrees. “Instead of building a grassroots cellulosic ethanol plant that’s going to cost hundreds of millions of dollars at commercial scale, this would give you a chance to bolt on some of the technology to an existing plant,” he says. “Therefore some of the capital investment would be less and give a chance to prove out the feasibility of cellulosic technology.”

James McMillan, principal engineer and group manager at NREL’s National Bioenergy Center, calls corn bran a low-hanging fruit for the corn ethanol industry. In particular, it’s appealing for ethanol producers who can use it to maximize the throughput of their plant without capital expenditures for additional fermentation capacity. The limiting factor is that processing corn bran will only produce so much ethanol, he points out. Quad County expects its technology, which does not involve fractionation or bringing in additional corn bran, to produce an additional 6 percent ethanol.

The next question is whether corn bran will officially qualify as cellulosic. Ashley Player, a chemical engineer at Frazier, Barnes & Associates LLC, tells EPM that sources at the U.S. EPA are considering its addition to the approved cellulosic feedstock list. “They were already looking at DDGS, and I brought up corn bran as an additional item to consider,” she says. “Direct final rules from the EPA come with no warning, so we do not have an estimated date for this approval.”

If it happens that would be a breakthrough for the first-generation industry. As the rules are currently written and interpreted, corn-based ethanol cannot qualify as an advanced biofuel—no matter how many technological improvements producers implement, says Kenneth “Pete” Moss, Cereal Process Technologies LLC vice president of marketing. CPT’s patented corn dry fractionation technology is installed at NCERC, and it processed the corn bran that NCERC used to produce cellulosic ethanol in the spring. Although the company has seen interest from the ethanol industry, the capital required to put it in place has, so far, stymied actual implementation. “This is beginning to change as more plants realize that long-term competitiveness will require investment in technology that diversifies product revenue streams and decreases energy and operating costs,” he says.

Another option is that producers could go with another grain-based feedstock, such as sorghum, McMillan points out. The U.S. EPA is currently reviewing an analysis that says that ethanol produced from sorghum at a plant powered by a biogas digester with combined heat and power has an estimated life-cycle greenhouse gas emission reduction of 53 percent, qualifying the fuel as an advanced biofuel under the RFS. No date has been established for a final decision. Payments are already made to ethanol producers who produce biofuels from noncorn renewable biomass, including sorghum, through the Bioenergy Program for Advanced Biofuels.

The Coproduct Question
Clearly, fermenting corn bran—whether it’s fractionated or fermented midstream—will alter the composition of a grain-based ethanol plant’s main coproduct, distillers grains. Quad County says output will decrease to about 85 percent and the new product will have more similarities to corn gluten meal than traditional distillers grains. NCERC plans to investigate this further, by funneling the high-protein, low-fiber coproduct produced in its September research project to a swine digestibility study that will be conducted at the University of Illinois. In concept, the coproduct will be more attractive to monogastric markets and perhaps even ruminants as well. Another possible benefit comes on the transportation side. “In terms of bulk density, you will be shipping more units of protein in the same physical volume of product,” says Caulpert, adding that this could have a big impact, especially for export markets. 

As long there’s a ready marketplace, it’s looking like the animal feed coproduct produced at corn-ethanol plants that ferment corn bran or fiber may be a high-value product. That’s important, considering that the annual ethanol benchmarking report released in September by Christianson & Associates PLLP revealed a trend of increasing importance to a plant’s bottom line. In the past, coproducts made up about 15 or 16 percent of total revenue, a number that grew to 23 percent in the first half of 2012.

One way to unlock larger volumes of cellulosic ethanol from corn bran is to go after the C5 sugars, McMillan says. However, conventional yeast used by ethanol producers only reaches the C6 sugars. Getting to the next level would require genetically modified yeast, which would mean some extra steps selling the resulting coproduct as an acceptable animal feed. Most companies seem reluctant to tackle the needed regulatory approval. “I would think that in most cases it wouldn’t be a big deal, but it is a big deal to prove it,” he says, adding that use of GMO would take exporting the product out of the picture due to regulations overseas.

The coproduct factor actually gives cellulosic ethanol from corn bran an advantage over cellulosic ethanol. Although there are many potential cellulosic ethanol coproducts, there are some big stumbling blocks, Aden says. Cellulosic plants can burn lignin to create steam and electrical power, but there’s not a big payback. “There is an old phrase that you can make anything from lignin but money,” he says with a laugh. On the other hand, purifying high-value coproducts, such as biobased chemicals, is costly. In addition, the markets for such products are much smaller than potential production volumes.

Author: Holly Jessen
Features Editor of Ethanol Producer Magazine
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