A Renewed Future

As ethanol producers search for ways to ease the pain of economic asperity, fractionation could be the answer. Renew Energy LLC implemented Cereal Process Technologies LLC's dry-fractionation system at its 130 MMgy ethanol plant in Jefferson, Wis., now the world's largest corn dry-milling operation. EPM investigates the benefits of installing this system.
By Anna Austin | January 03, 2009
Jim Giguere's work on corn fractionation technology didn't stop when his process was first being used in the 1980s, or when he secured the final patents in 1994. The chemical engineer continued to refine the process and make it more efficient long after he retired. Today his endeavors are being employed by Cereal Process Technologies LLC, who introduced it to the ethanol industry.

Its first commercial application in the world of ethanol came in January 2008, when Renew Energy LLC commenced operations at its 130 MMgy ethanol plant in Jefferson, Wis.

Renew's ethanol plant was built on the site of what was once the largest malting plant in the world, which the company purchased from Cargill Inc. in 2006. Using the existing resources such as the storage units and water and electric utilities, its metamorphosis from malting plant to ethanol facility was smooth, despite the fact that the developers were attempting to build more than a typical ethanol plant. "We were looking for a way to build a facility that would have added value and not be the traditional commodity-based ethanol plant," says Scott Busch, Renew Energy product merchandising and marketing manager. "We wanted to differentiate ourselves by having different feed products."

After researching different fractionation options, Renew decided that the CPT system was its best choice. "First, because dry fractionation is more economical than wet," he says. "And the horsepower required for this system—the cost of running it and overall capital costs—was less than other systems."

Today the facility can process 50 million bushels of corn annually, which is about one-third of the corn dry-milled in the United States. The technology has also provided Renew with a value-added feed product, allowing the company to serve additional markets.

Dissecting the Process
The CPT corn dry fractionation process differs from the typical ethanol plant corn processing method, says Reg Ankrom, director of market development for CPT. "Conventional ethanol plants, which hammer mill whole corn, don't separate nonfermentable germ and bran from the starch component," he says. "That means lower efficiency and higher-cost ethanol production, and the loss of valuable coproducts."

The CPT process separates the corn kernel's endosperm, or starch, from the germ and bran, which are not used to make ethanol. "A few ethanol plants use a wet-milling process, which requires steeping the corn in a heated solution to achieve separation of the corn's constituents," Ankrom says.

In the CPT process, once the corn is cleaned of stones, dust and other foreign matter, it is tempered as necessary, and held for 24 hours in tanks to attain proper moisture content to prepare for fractionation. The corn is then passed through a degerminator, a patented process that separates the corn germ, Ankrom says. The resulting corn pieces are passed through two roller mills and then sifted. The larger pieces are returned to the roller mill to be further reduced.

Aspirators separate the lighter bran from the germ and endosperm streams and a bran finisher is used to remove about 1 percent more of the endosperm from the bran. "The resulting high-purity DDC (degermed, debranned corn) stream can then be conveyed directly to the ethanol plant or to temporary storage," Ankrom says. "CPT fractionation is built in modules, which more closely relates capital cost to plant size.

Modular systems permit maintenance without shutting down the entire fractionation or ethanol plant, Ankrom says. A single module can be shut down and repaired separately. If necessary, the entire system can be slowed down to process only 5 bushels an hour.

Each module typically processes about 650 bushels of corn per hour, and is capable of processing up to 750 to 800, if an operator needs to catch up after a dry spell. "The sweet spot is about 650 though," he says.

CPT's Fractionation Advantages
The benefits of installing CPT's fractionation system go beyond what typically come to mind when considering fractionation, Ankrom says. Of the DDC stream, no less than 80 percent by mass of the incoming whole corn will be contained in the collected stream, and a minimum of 91 percent of the starch in the incoming whole corn will be contained in the DDC stream to the ethanol plant. "When compared with available starch in the whole kernel—not chemically bound in the corn germ or bran, and therefore, not separable—the DDC fractionation captured by CPT's technology amounts to approximately 95 percent of starch available for separation," Ankrom says. A minimum of 65 percent of the crude fat, or oil, from the incoming whole corn will be contained in the collected corn germ stream. Of the oil available for separation, not bound in the bran or endosperm, CPT's process typically yields 86 percent of the oil available in the germ portion, he says.

Ankrom tells EPM that the CPT fractionation system reduces about 17 percent of the corn's nonfermentable materials, in turn leading to a reduction in energy proportional to the level of the inert materials.

A 35 percent reduction in the drying requirement can also be achieved. "This is a result of the removal of the nonfermentable solids, and is a significant portion of the total plant energy savings," Ankrom says, adding that the CPT system can drive down the cost of ethanol production to about 22,000 British thermal units per gallon.

Other energy savings include the elimination of approximately 1.2 megawatts in the hammer mill load typically required for a 100 MMgy ethanol plant, and only two megawatts of totally connected load for the fractionation plant, Ankrom says. "This is considerably less connected energy than most dry-fractionation systems," he says. The CPT system at Renew uses 2,700 connected horsepower. "We understand that is about half the horsepower required at a typical corn-milling operation," Ankrom says.

In addition, Renew's water requirement has been reduced to about 2.7 gallons per gallon of ethanol, a 33 percent savings. "At Renew, wastewater has been reduced by 50 percent," Ankrom says. "They've done a great job doing this by recapturing and reusing."

Ethanol and Then Some
The fractionation process separates the corn germ, which is the living part of the seed that contains growth elements and oil, and the bran, the tough, fibrous outer layer.

The oil in the corn germ can be extracted and refined in a separate process for use in food-grade products. The de-oiled corn germ resulting from the fractionation can be used for feed, or mixed with the bran and the syrup from ethanol production to create a form of corn gluten feed. "The bran can be used as a feed source," Ankrom says. "Including providing a medium for carrying the syrup, and, at more than 8,100 Btus per pound, it also can be used as a fuel source."

The low oil and bran content of the DDC stream results in a high-protein meal, he adds. Renew's feed product contains crude protein of about 40 percent, which reduces the need for supplemental protein sources when used in animal feed.

Renew's patented, high-protein Renew Meal, which is produced using Cargill Animal Nutrition's Reveal technology, can be used as a substitute for soybean meal.
CPT's equipment is unique because the operator can change the makeup and tailor the feed to the client's needs. "The operator can vary the streams," Ankrom says. "For example, normally the high-protein meal comes out the back end and has a lot less oil. If a client asks for slightly more oil for energy for swine, the process can easily be varied to do this."

Renew also sells liquid carbon dioxide, a byproduct of ethanol production. After it's collected and cleaned of impurities, the company sells it to the food industry as a refrigerant, carbonator for soft drinks or dry ice.

Cost and Payback
As with any project, different variables can affect the cost and how long it will take to pay for the technology. "Site condition and requirements, such as the fractionation plant's proximity to the ethanol plant, conveyance and incoming and outgoing loading facilities, among others, impact cost," Ankrom says.

Ankrom estimates that it costs $30 million for a nine-module system, such as the one serving Renew. "Payback is subject to many variables, including corn costs, ethanol values, coproduct values, transportation costs and so on," he says. "Given these considerations, our calculations show a payback within two years."

CPT's technology can add more than 20 cents per gallon to the producer's net income when built in or added to an ethanol plant, Ankrom says

"We're in a paradigm shift," Ankrom says. "Ethanol is not as glamorous as it was just a few years ago, but it's still important to the nation today as a path to a cleaner environment and reduced dependency on foreign oil. Farmers are enjoying higher corn prices—a good thing—but ethanol values have not matched the increase in oil prices. The result is squeezed ethanol margins. The challenge for producers is to keep ethanol healthy in a more challenging market."

By taking advantage of the value in the corn feedstock, which in most cases is already paid for, ethanol producers who make fractionation part of their business model can produce their primary product more economically and add new revenue streams from the higher-value coproducts. "Fractionation adds up to higher profitability and sustainability," Ankrom says.

Anna Austin is an Ethanol Producer Magazine staff writer. Reach her at aaustin@bbiinternational.com or (701) 738-4968.