Incubation Through Integration

A handful of larger companies are working diligently toward uprooting cellulose conversion technologies from the labs and transplanting them to pilot-scale facilities. Integrating and further refining cellulose process technologies within existing ethanol plants is likely to be the irresistible medium that's already incubating the future of celllulosic ethanol.
By Ron Kotrba | March 01, 2006
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Ockham's Razor is a principle almost every Philosophy 101 student learns. It dates back to the 14th century, the origination of which is attributed to William of Ockham, an English logician and friar. A common explanation of Ockham's Razor is, well, that the simplest answer is most likely the correct answer. This idea has been indispensable in the development and advancement of modern science, and it has found a home in the rigors of the Scientific Method—mainly as the great expeditor of hypotheses. When multiple theories are presented in hopes to provide answers to scientific questions, Ockham's Razor dictates that the hypothesis with the least number of unproven assumptions is most likely the correct choice. It's not foolproof, but it has served science well as a guide throughout the last 600 years, to one degree or another.

Simple plans emerge
Perhaps Ockham's age-old supposition can offer some assistance in accurately predicting certain aspects of what the future U.S.-based cellulosic ethanol industry will likely resemble. It's no secret that different technologies exist out there at varying levels of effectiveness for the conversion of biomass to ethanol—in addition to other higher-value coproducts. Those technologies may not be optimized, but they do exist. Several gray areas remain though, but when it comes to predicting how—and at what point—a cellulosic ethanol industry will take hold in the United States, one might want to keep Ockham's Razor in mind.

Some of the most notable companies involved in partnership agreements to bring cellulose technologies from the lab to the next step of proving yield, capacity and overall process effectiveness of the different production techniques include Abengoa Bioenergy R&D, DuPont and Broin Companies. Each of these companies is actively involved in a Cooperative Research and Development Agreement (CRADA), a formal agreement between U.S. DOE national laboratories like NREL, various production facilities and integral partners. "Broin, Abengoa and DuPont all responded to a 2002 [DOE] solicitation," says John Ashworth, partnership development team leader at NREL's National Bioenergy Center. The purpose of this solicitation was twofold, Ashworth explains. One objective was to provide incentives for the industry to further develop cellulose-to-ethanol conversion technologies through pilot-scale operations. The solicitation also sought answers to questions about how to integrate cellulosic materials into existing dry-grind or new ethanol plants, Ashworth tells EPM.

Abengoa Bioenergy R&D
According to Gerson Santos-Leon, director of Abengoa Bioenergy R&D, Abengoa's current program to develop cellulose technologies has two steps. "Step one is the optimization of the dry mill technology, and that we are doing in York, Neb.," Santos-Leon tells EPM. "About two years ago, we built the starch pilot plant there, and we've been … optimizing the production of ethanol from cereals." Corn, wheat, barley and sorghum are all being tested at Abengoa's York pilot plant. "We're also in the process of building a second pilot plant (in York) to develop the biomass fractionation system, the second step in our partnership with the DOE," Santos-Leon says. Abengoa anticipates the biomass fractionation plant in York to be operational next fall using corn stover as the initial feedstock. "Our goal is to develop and demonstrate an integrated biorefining process, which would include the fermentation of both pentose and glucose sugars."

Abengoa has an even bigger project in Europe. "In Spain—in partnership with Ebro Puleva and the European Union 5th Framework Programme—we are demonstrating our enzymatic hydrolysis technology," he says, referring to Abengoa's first biomass commercial demonstration. "What we want to do in [the city of] Salamanca is demonstrate the pretreatment process and the enzymatic hydrolysis of cellulose on a commercial scale using wheat straw. This plant is co-located with the starch plant in Salamanca, sharing utilities and support systems."

Abengoa anticipates the Salamanca starch plant with which the demonstration plant is being co-located to begin operations by mid-year at the latest, while it says the 2 MMgy wheat-straw-to-ethanol plant next door should be up and running by late this year or early next year. According to Santos-Leon, the demo facility in Spain will not ferment the pentose (C5) sugars. Only glucose (C6) from the cellulose hydrolysis will be fermented into alcohol. The pentose-laden residue will be mixed with animal feed for further studies.

Abengoa's partners include NREL, Genencor, Novozymes, SunOpta and Ray Katzen, the distinguished professional engineer (see EPM's February 2006 profile on Katzen, "The Project of a Lifetime") who is retained by Abengoa for consultation.

Broin's practical approach
Broin Companies is another major player involved in researching and developing a better cellulose-to-ethanol conversion process. Although Broin's CRADA involves integrating cellulosic conversion with existing processes, the specific process with which Broin hopes to merge its cellulose technologies currently under development is Broin's trademarked corn fractionation process known as BFrac.

"BFrac is not a cellulose-to-ethanol process," says Rob Broin, Broin Companies chief technology officer. "What we're working on in our CRADA is converting the BFrac fiber fraction into ethanol." The fiber feeding Broin's cellulose conversion R&D is being directly supplied by corn fiber gained from the company's proprietary BFrac corn fractionation process. Like Abengoa and most other companies in pursuit of optimizing this technology, Broin Companies' efforts have been somewhat splintered due to the non-existence of a good organism to ferment both C5 and C6 sugars. "Another thing we see that needs more work is the pretreatment process," Broin tells EPM. "There is a lot of work going on in that area, but I think a lot of work still needs to be done to find an optimum pretreatment process and to make sure that the ethanologen—or the micro-organism—that gets developed works in conjunction with the pretreatment process." Broin is referring to the inhibitors produced by some of the cellulose pretreatments under development today. Enzymatic hydrolysis can follow pretreatment of the biomass, but Broin says some of the pretreatments out there produce too many inhibitors, and there isn't an organism available that can withstand those at any relative alcohol concentration. "There's a real Catch-22," Broin says. "We can pretreat the corn fiber, but we can't get a good fermentation of the resulting hydrolysate. It's a dilemma that's fairly well-known."

Regardless of any industry-wide R&D shortcomings in "finding" this multi-tasking yet elusive ethanologen, what's attractive about Broin's approach is that the company already has experience integrating its other technologies at several of its facilities. Broin's Project X (BPX), the company's own raw starch hydrolysis, has been successfully implemented on a commercial scale at 10 Broin ethanol plants. BFrac technology has also been integrated at two Broin plants. Moreover, BPX and BFrac compliment each other. With Broin's experience in technological integration, the company could very well have an edge in the cellulosic ethanol industry before it even exists.

DuPont's different direction
DuPont's CRADA, a four-year, $38 million DuPont-led consortium—$19 million of which is being supplied by the DOE in matching funds—has a different direction than the other R&D efforts named. DuPont calls this project an integrated biorefinery. "DuPont has a process for converting sugars to polymers (1,3 propanediol), trademarked as Sorona, which is a premium fiber," Ashworth tells EPM. "They originally started making this from petroleum, but the company makes it from purified sugars today."

According to Ashworth, DuPont's project has two parts: one part DuPont is conducting on its own, and the other is with NREL. The former project processes corn kernels so its organism can make 1,3 propanediol. The other aspect of the project uses whole stalks and the corn itself—and through processing, the grain goes one way and the biomass goes the other, Ashworth says. "There are two products to make this cellulosic ethanol plant work," he says. "Polymers, where the value is, and ethanol, which is sort of the flywheel to drive the plant." DuPont is also looking at the high-energy lignin to power the plant.

DuPont's partners include NREL, Diversa Corp., John Deere and Michigan State University.

Synergies too great to ignore
According to Murray Burke, vice president and general manager of SunOpta Inc.—the Brampton, Ontario-based company providing its steam explosion pretreatment technology—it's important to look at the oil and chemical industries' approaches at process evolution over the years as a guide to how this industry's processes might evolve. A major oil or chemicals company would develop new processes or process techniques in a lab, followed by selecting one of their refinery sites to "‘clip on' the smallest possible process model to prove the process technical data and process economic outcome," Burke tells EPM. "This would form the basis for the next grow-out size of the process."

Essentially, there are too many advantages in either co-locating or integrating cellulose processes into existing starch-based facilities to ignore—and, remembering Ockham's Razor, it does appear to be the simplest way to building a cellulosic ethanol industry.
"[A clip-on cellulose plant could] utilize the synergies of an existing site," Burke says. Just some of the advantages include sharing operators, maintenance responsibilities, utilities, infrastructure and management. A cellulose process line or "clip-on" could leverage muscle from virtually every corner of an existing facility.

"Our hybrid technology concept integrates cellulosic and starch technologies," Santos tells EPM. "When you talk about that, you talk about sharing a lot of systems. If you look at the dry mill system, and you look at the cellulosic process, the primary differences between these processes are the pretreatments. … Our objective is to integrate some of the key unit operations like hydrolysis, fermentation and distillation, and share the utilities and support systems. … We'll have two different pretreatments at the front end but when you get to the backend, it will be the same. We will have glucose from starch and glucose from biomass, so what you'll see is bigger fermentation tanks. Then, for the C5 (pentose sugars), we will use a recombinant organism to ferment the pentose. That would be a separate fermentation."

Burke says one of the most feasible and seemingly imminent approaches to integrating cellulose and dry (or wet) milling operations is exactly what Broin is investigating through its CRADA—using "waste" streams like the corn fiber gained from fractionation of corn kernels to not only produce ethanol from the starch but also from the lignocellulosic materials in the kernels. "With the new dry mill corn fiber separation in the front end coming into play, there will be large quantities of cellulose, starch and hemicellulose streams becoming available," Burke predicts. "With [distillers grains] prices facing downward pressure, the use of these corn fiber streams as feedstocks will become more and more attractive. They typically have 20 percent starch, 20 percent cellulose and 25 to 30 percent hemicellulose. These streams will be priced below [distillers grains]. Hence, this is likely the number one synergy to be seen."

Burke notes other benefits to integration, like raw material diversification to allow for flexibility of supplies in case of drought or to avoid the woes of having only a single supplier of input goods.

Tackling challenges
It's safe to say that all of the companies involved in this pursuit differ in isolating what challenges remain. However, if any doubts existed before Jan. 31 as to whether or not the development of technically viable and economically competitive cellulosic process technologies is a priority on the U.S. government's "to-do" list, surely those doubts were cast aside after President Bush's State of the Union address, during which he prioritized the commercial demonstration of cellulosic ethanol within a six-year timetable.

Nevertheless, the issue of developing a simultaneous, multi-functioning ethanologen to convert C5 and C6 sugars is key to optimizing not only the efficiency of integrating cellulose- and starch-based processes, but also the economics. "That is an important part that's missing," Broin says. "It's really holding back the future of the cellulosic ethanol industry."

According to Ashworth, NREL has an organism that can ferment both pentose and glucose sugars, and it's being used with DuPont's project. "Diversa has a specialty mix of enzymes to react with our pretreatment," Ashworth reveals. "We're using the organism NREL developed a while ago, and the result will be ethanol." Although Ashworth states that NREL has the sought-after organism, more work is needed. The key is finding a similar organism, or enhancing this particular one, to ferment both sugars "at high speed," he says.
Similarly, optimizing the pretreatment of lignocellulosic materials is also crucial. "Industry experts are now acknowledging that the pretreatment stage is the critical step to the entire process outcome for the lignocellulosics-to-ethanol process," Burke says. "The SunOpta Stake Technology pretreatment system is applicable to virtually all published pretreatment processes. It is the only system in the world that has a multitude of proven industrial applications and sites."

Although financing these cellulosic ventures will also present its own group of hurdles, there won't be nearly as many obstacles to financing an integrated plant, as there would be for a standalone plant.

And what catalyst will spark the proliferation of these process-integrated ethanol plants? Well, experts differ on that too. Some say it's going to be when cellulosic processes are economically competitive with current starch-to-ethanol production. Santos-Leon thinks otherwise. "The issue is not to have a technology that is more competitive with starch," he tells EPM. "The whole objective is to have a technology that will complement the starch technology to expand the ethanol market in the transportation sector."

Javier Salgado, CEO of the Abengoa Bioenergy Business Group, believes the integration of starch and cellulosic technologies into hybrid plants is the most viable option to overcome the financial barrier and get the cellulosic ethanol industry off the ground. "Our hybrid plant concept lowers the technology risk and the capital requirements—essential for an economically viable project—to secure financing in the marketplace," Salgado says. "Our approach, along with the president's Energy Initiative, will launch the cellulosic industry to meet our growing energy needs."

Ron Kotrba is an Ethanol Producer Magazine staff writer. Reach him at [email protected] or (701) 746-8385.