Going Beyond the Corn Kernel

Poet LLC didn't have far to travel to find a feedstock that it can use to turn the corner on cellulosic ethanol. During the 2007 corn harvest, the company showcased its plans to use corncobs as the primary feedstock for Project Liberty, its cellulose-to-ethanol expansion project at Poet Biorefining Emmetsburg in Iowa.
By Michael Shirek | January 10, 2008
Jeff Broin is no stranger to corn fields. As the chief executive officer of Poet LLC, the nation's second-largest dry-mill ethanol producer, his business is tied directly to the Midwest corn growers. As the company begins to explore the world of cellulosic ethanol, however, a corn field might not seem like the obvious place for Broin to address the media regarding his company's future in the next-generation production of ethanol. As it happens, Broin spent a windy afternoon in October at a podium situated just beyond the rows of a standing corn field near Hurley, S.D. He talked about Poet's plans to extract 38 percent more ethanol from each acre of corn already dedicated to producing the fuel from starch at some of its 21 operating ethanol plants and another five that are under construction. The company is expanding its Iowa-based Poet Biorefining Emmetsburg facility, which will serve as the blueprint for its cellulosic ethanol future, and using 4,000 acres of South Dakota corn to conduct its first round of testing on corncob harvest and storage processes.

Poet used those 4,000 acres as its laboratory during the fall corn harvest. The company conducted experiments on equipment used to harvest the grain and cobs, and worked extensively with corncob piles, trying to find the best combination of harvest technique and storage. Although the testing concluded in November, Poet is still analyzing those results and plans to release some of its findings to the public early in 2008. "I think the time is getting very close where we're going to be able to make large amounts of ethanol from cellulose," Broin said at the harvest demonstration in South Dakota. "It's the alignment of multiple things. It's the opportunity to
develop a process which I think our company has the capability to do, it's the enzyme companies' interest in developing an enzyme at a price that we believe is viable and it's the evolution of multiple microorganisms that have the potential to process the ethanol. In my opinion, those things are all coming together in the next few years."

Although Poet can only control the first part of that equation, it's well on its way to developing the processes that will allow the company to efficiently gather cellulose for conversion to alcohol. Is this the turning point for commercial-scale cellulosic ethanol? Will Poet's 25 MMgy of ethanol produced at Emmetsburg be the first competitively produced cellulosic ethanol on the market? Will Poet's corncob harvest techniques find their way to a large number of America's corn growers who are already making a pass through fields with harvest equipment that could be easily modified to pick up a second valuable product?

Harvest and Storage
It's not exactly breaking news that farmers are harvesting corncobs, and Poet isn't the first company to hatch the idea of removing the cob from the field when the grain is harvested. Farm implement manufacturers have already developed equipment that can harvest the cob in the same pass as the grain. But Poet is looking beyond simply harvesting the corncobs when Project Liberty comes on line in 2011 and needs a steady supply of cellulosic feedstock.

Poet biomass manager Reed Mayberry says the company's fall harvest experiments were designed to test as many permutations of harvest and storage as was feasible. The company is hoping to develop a catalog of techniques that can be used by individual farmers to execute the most efficient method of adding value to their corn crop. "We're trying to provide options for a guy that farms 300 acres just as well as a guy that farms 3,000," Mayberry says. The one-size-fits-all approach will not work in the real world where not every farmer is equipped with the same implements, and not every farmer gives the corn harvest the same priority.

With that in mind, Poet focused on two harvest techniques. The first involves little modification to combines and uses equipment already available commercially to harvest whole corncobs. The second involves more modification to the combine and gathers the grain and cob in the same tank, requiring a second process to separate the two. Mayberry says both techniques have a place in the company's plans and both were on display at the company's harvest day.

The first method modifies a combine with nothing more than a hitch used to pull a cob caddy. Mayberry says this technique is the simplest way to harvest cobs and is available to virtually every farmer who currently harvests corn. "The only real modification is that hitch," Mayberry says. "[The combine] was a standard, stock machine that was pulling a cob caddy. It catches everything that comes off the back of the combine and separates the cob from the rest of the stover." The advantage of this technique is easy to see: No significant modification to the combine with the whole cob completely separated from the grain. After a pass through the field, the farmer simply dumps the caddy and piles the cobs.

The second method doesn't come in a neat package from an equipment manufacturer. In order to harvest a corn and corncob mix (CCM), a farmer must change combine settings and some minor parts. "[We change] several things in the inside of the rotor combine that allows it to now capture not only grain, but cobs in a commingled fashion in the grain tank," Mayberry says. The process involves minimal costs and isn't very complex, something that's important to its viability. "We wanted to make a system that was very flexible that had the [ability] to go from soybeans to corn within a couple hours of modification," he says. "By the end of the season we feel pretty comfortable that it can be done in less than about 20 minutesthat modification from corn and corncob mix either back to straight corn or back to soybeans or wheat or any other crop." The CCM consists of grain mixed with cobs that are broken up as they pass through the combine.

The downside to CCM is that the mix must be separated. Poet's engineers have developed a process that separates the grain and cob. Right now, the separation process involves two pieces of machinery. The company hopes to have the process simplified as the 2010 harvest comes along and farmers are producing cobs for Project Liberty.

Poet is focusing on more than one harvest method because it wants corn growers to have more than one option for bringing in the cob harvest. "Different systems fit in differently with different farms," Poet feedstock development engineer Mark Dilts said at the harvest day. "One of the reasons we're doing the study this fall is so we can tell farmers how it will affect their production."

Not only is Poet developing more than one harvest technique, the company is also working with many storage options. Unlike the cob harvest equipment, the long-term storage required for Project Liberty hasn't been developed. The company started from scratch and came up with 20 different techniques for piling cobs in order to find the method that will preserve the crop and allow Project Liberty to operate with a steady supply of quality feedstock throughout the year. Poet worked with approximately 120 piles in the experiment, three replications of each of the 20 techniques for both whole cobs and the broken cobs produced with the CCM method, Mayberry says. The material difference between the whole cobs and the broken cobs is significant, but Poet is still looking at data to determine the longevity difference between the 4- to 6-inch whole cobs and the 2- to 3-inch broken cobs.

The Future
"With Project Liberty coming on line in 2011, we have to be producing corn cobs from the farmers in 2010 to some magnitude," Mayberry says. "That allows us to have a 2008 test plant as well as a 2009 test plant, which we are evaluating right now. It will take place in South Dakota and Iowa as we roll into 2008 and beyond." Although Poet has no definitive plans regarding the size and scope of the 2008 test plant, Broin told EPM that the company will be active in refining its methods in the new year. "We are certainly going to wait and see some of the early test results on the research happening here before we make that decision," he said. "I would assume it would be at least as large or larger next year."

When Project Liberty at Emmetsburg is operating, Poet estimates that it will require the cobs from 275,000 acres of corn to produce cellulosic ethanol. Mayberry says the company is optimistic that it can meet its goals in harvesting that amount of feedstock and that it will have developed methods to store the material by 2011. "One of the things that I like about it is that our feedstock for Project Liberty is being grown today everywhere in the Midwest," he says. "It's not an adaptation to a new crop, a new cropping system [or] new equipment. It's being raised on every acre of corn that's out there today. It's a value-added opportunity for people to not only capture corn, but cobs for cellulosic ethanol."

If Project Liberty is a success, Poet says it can take the technology to virtually any of its other biorefineries and expand those with a cellulosic ethanol component. "I think the interesting thing about our plan is that it's very replicable," Mayberry says. "As we now have 21 plants in the U.S., I like the idea that the footprint on each plant is built to be very replicable. When Project Liberty is up and going, this is a footprint that could be added to any of the other Poet biorefineries."

Poet says that harvesting the corncob and using it to produce cellulosic ethanol will increase the yield of fuel ethanol from an acre of corn by 27 percent. The company will also use its BFRAC fractionation technique to separate the hull from the corn kernel and plans to use that fiber in its cellulosic ethanol process to get 11 percent more ethanol from an acre of corn. That 38 percent gain is the culmination of more than a decade of work by Poet to develop a cellulosic ethanol process. "Our company's been looking at cellulosic ethanol for about 15 years and we just recently decided that cellulosic was the direction to go," Broin said in October. "About a year and a half ago we got very interested in the area and really started targeting the processing of cobs as well as the corn fiber into ethanol. Our original interest in cellulosic ethanol goes all the way back to the invention of our BFRAC process over seven years ago."
Mayberry says the company will release some of its findings from the cob harvest early in 2008 and from there will determine how to conduct its 2008 harvest testing. Poet is working with original equipment manufacturers such as Case IH and John Deere, whose level of participation will have some bearing on the scale of the operation. Broin said he's confident that 2007's findings will be trumped by 2008's and that Poet will be ready to roll out simple, efficient and effective methods to harvest corncobs by the 2010 harvest. "We've already found some efficient ways to collect cobs in the field and I think that there will be even better methods in the future," he said. EP

Michael Shirek is the Ethanol Producer Magazine online editor. Reach him at mshirek@bbibiofuels.com or (701) 738-4962.