Microwavable Distillers Grains

Winnebago, Minn.-based Corn Plus LLLP is interested in an innovative distillers grains microwave drying technology that could bring the facility one step closer to becoming energy independent.
By Bryan Sims / Photos By Doug Wollin | May 09, 2008
With more than 20 years experience in the industry, Keith Kor knows the impact of high energy costs on an ethanol plant, and how important it is to capitalize on existing resources to optimize energy efficiency. That experience and knowledge has prompted Kor, who became general manager of the 44 MMgy Corn Plus LLLP ethanol plant in Winnebago, Minn., in 1994, to implement several cutting-edge energy saving technologies. "Getting more value out of what you already have," Kor tells EPM. "That's the key right there."

Corn Plus is also driven to reduce its energy costs because of the potential for higher corn prices as fewer acres will be planted this spring, compared with the previous year, and a growing demand for the commodity in the United States and overseas.

With that in mind, it wasn't surprising when in mid-March Corn Plus hosted a three-day pilot test on a distillers wet grains microwave drying process. Corn Plus is the first ethanol plant to express interest in such technology. The process was developed and patented by Cellencor Inc., an Ames, Iowa-based technology research company focused on developing processes that enhance ethanol production. The pilot test was designed to determine the economic feasibility of the unit in an operating ethanol plant.

Madison, Wis.-based Alliant Energy Corp., the utility service provider for Corn Plus and marketer of Cellencor's microwave drying unit, introduced the two companies. Alliant Energy met with Cellencor representatives about a year ago to help the start-up firm make connections with businesses such as Corn Plus, which was the first ethanol plant in Alliant Energy's service territory. According to Dave Wentzel, strategic account manager for Alliant Energy, the facilitation of the pilot test at Corn Plus is one of a suite of services the utility company offers its customers. "Our goal is for our customers to be low-cost producers in the industry," Wentzel says. "Cellencor is certainly a key component of that going forward."

In tests conducted at Iowa State University's BECON Facility, Cellencor's industrial microwave drying line was proven to be more efficient and reliable than traditional energy-intensive, natural-gas-fired distillers wet grains dryers. Initial calculations indicate the system should start paying for itself in two to five years, but the partners are hopeful that the commercial testing at Corn Plus will yield more conclusive data. Cellencor gets its microwave drying equipment from New Hampshire-based The Ferrite Co. Inc., which touts itself as the world's largest industrial microwave manufacturer. Cellencor holds exclusive marketing rights to Ferrite's technology globally.

Using this technology, Corn Plus predicts it will result in a reduction in operating costs of up to 20 percent. "Microwaves use less energy to dry the product than natural gas systems because they work from the inside of the product out, as opposed to the outside of the product in," says Cellencor President and Chief Executive Officer Bruce Wicking. Additionally, by using a lower heating temperature—200 degrees Fahrenheit—damage to amino acids in the distillers grains is reduced. That damage can dramatically impact distillers grains quality, according to Wicking. "It actually worked out very well," Kor says. "The product dried well, looked very nice and smelled nice. With conventional drying you get variations in smell or color based on whatever dryer you have or how much syrup you have on it and so forth. This system didn't affect those factors."

Although not all of the pilot test results were available at press time, the parties involved expect the results will be positive. So far, "the results we got from Corn Plus are very encouraging in terms of energy usage, environmental benefits, generation of carbon credits and lower water usage," Wicking says.

For Corn Plus, the microwave drying technology will not only allow the company to save on natural gas costs, but also to be a model for others in the industry looking to curb production costs.

Benefits Upon Benefits
In addition to reduced energy use and the resulting cost savings, there are other advantages to using the microwave technology, including reducing a plant's water use. In a typical corn-based plant, it takes 3 to 4 gallons of water to produce 1 gallon of ethanol. With the Cellencor microwave drying system, the company estimates that it could retain 20 percent to 25 percent of the water used in the drying process. "We can get the vast majority of the [water] and recycle it back into the plant," Kor says. "My goal is to not only reduce energy costs but also reduce water consumption. Ethanol plants are getting bombarded with the water usage issue."

The microwave drying technology also reduces harmful volatile organic compound (VOC) emissions. Compared with traditional natural-gas-fired rotary drying drums, Cellencor's microwave drying technology reduces the amount of dryer vapors from entering the regenerative thermal oxidizer (RTO) before exiting a plant's outside emissions stack. "The emissions results looked very encouraging," Kor says.

ISU researched Cellencor's enzyme-enhancement process on another ethanol plant coproduct—dried distillers grains with solubles. The technology adds enzymes prior to the low-temperature drying, improving the nutritional value of the coproduct 10 percent to 20 percent. After its tests at Corn Plus, Cellencor will continue to refine the design of its microwave drying process and conduct feed trials this year. As part of a long-term trial arrangement with ISU, Cellencor will compare dried feeds using the microwave technology with feed produced using conventional natural-gas-fired rotary drying drums, according to Wicking. "Obviously, we have further objectives in terms of extra benefits that come from using microwave dying, particularly in the area of nutritional advantages, but they'll largely come in as a second tier development," he says.

The microwave technology can be applied both to new facilities and as a retrofit to existing plants, Wicking says. Depending on the physical nature of a particular ethanol plant, one method would be to remove an existing dryer, or locate the microwave dryer in a vacant building. Another option would be to install it outside in a 40-foot shipping container. This option would be especially useful for producers looking to supplement existing drying capacity with a modular type add-on. "[Installation] would be very noninvasive in terms of the way in which the technology can be placed within the plant structure," he says. "It doesn't affect operating conditions."

Cellencor stresses that its customer relations doesn't end after installation. The company intends to offer additional products and services, including a warranty package to support the 20- to 30-year lifespan of the technology and a 24/7 maintenance service arrangement, which is part of its licensing and intellectual property agreement with Ferrite, Wicking says.

Cellencor's technology has attracted the interest of four or five other ethanol producers both here and abroad. For the time being, however, the company is concentrating on the analysis derived from the pilot test at Corn Plus, its first potential commercial customer, Wicking says. "Once that is done and we've got our own understanding of the commercialization process and the full suite of benefits that are available from the technology to the plant, we'll be able to rapidly expand the marketing of the technology across 2009 and 2010," he says.

Synergizing Energy Efficiency
Cellencor's microwave drying technology would complement the variety of innovative technologies that already exist at Corn Plus as it evolves into a fully-integrated and energy independent "island."

The company's innovative fluidized bed reactor began operation in 2005, enabling Corn Plus to cut its natural gas consumption by 52 percent. Similar to the microwave drying technology, Alliant Energy helped Corn Plus adopt the fluidized bed reactor technology. According to Wentzel, these two technologies working in tandem would negate running a natural gas line to the facility. "We envision with the fluidized bed reactor and the Cellencor microwave technology that you would have a natural gas-less ethanol facility," Wentzel says.

Corn Plus also created a new revenue stream by installing two pelletizers—one for ash and the other for distillers grains. Corn Plus pelletizes or "prills" the ash residue from the syrup that's burned in the bed reactor process and turns it into fertilizer. The company also pelletizes distillers grains at a maximum rate of 10 tons per hour.

Corn Plus was the first ethanol plant in the United States to install wind turbines. The two turbines came on line in March and generate 4.2 megawatts per hour when operational. The wind turbines are used in tandem with an on-site electrical substation that Corn Plus added in 2002. For Kor, the reduced cost in natural gas usage coupled with naturally produced electrical power affixed on site is a crucial step in meeting the plant's target of energy independence. "The electricity that we produce is under a nickel per kilowatt," he says. "You're still using electricity to dry the distillers grains so you'll have energy, but you'll reduce all your natural gas from drying. You'll still have electrical power at a reduced cost so you're just swapping energy there."

To top off its accomplishments, Corn Plus joined the Chicago Climate Exchange in October 2007, making it the first independent ethanol producer to join and monetize carbon credits through the CCX. Carbon Green LLC and its partner Environmental Credit Corp. facilitated Corn Plus joining CCX. Reducing natural gas costs provided Corn Plus with $240,000 (63,000 tons) worth of carbon credits on the CCX and in April it was the first to execute carbon trading electronically via the CCX Trading Platform.

Bryan Sims is an Ethanol Producer Magazine staff writer. Reach him at bsims@bbibiofuels.com or (701) 738-4962