Gumming up the Works

This year's delayed harvest presents farmers and ethanol producers with several challenges—from dealing with high moisture corn to testing moldy corn for mycotoxins.
By Holly Jessen | March 16, 2010
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Corn growers brought in another big harvest, with record yields reported in spite of a late spring. But delayed planting brought a delayed harvest, and with it a big year for wet corn. Paul Bertels, director of economic analysis for the National Corn Growers Association, says he heard of farmers taking off corn anywhere from 14 to 40 percent moisture in the nation's 2009 harvest. The Renewable Fuels Association reported it too. "Initial 2009 harvest reports in many locations show grain moisture ranging from 25 percent to 30 percent, as opposed to the more typical harvest levels of 18 percent to 23 percent," according to a RFA report on corn quality.

All that wet corn creates problems for many ethanol plants. Glacial Lakes Energy LLC, a 100 MMgy ethanol plant in Mina, S.D., typically accepts corn of 16.5 percent moisture or lower. This year the corn coming in was a couple percentage points higher. At maximum, the plant's hammer mills can handle about 18 percent moisture corn before the wet corn gums up the works. "That's probably even pushing it," says Jason Wambach, corn merchandiser at the plant.

Although most ethanol plants don't have on-site corn dryers, Glacial Lakes is installing one as well as increasing storage capacity and adding a receiving pit. The $2.75 million project, which was financed partially through state economic development money, was on track to be completed in March. Glacial Lakes-Mina made the decision to install the dryer because 2009 was the second wet year in a row. In fact, Wambach says, in 2008 the ethanol plant had to shut down ethanol production for a few weeks while waiting for corn to be dried off site. "This year we didn't have to shut down," he says, "but we did have to trim down."

RFA listed several things besides drying the corn that ethanol producers should be aware of in a high moisture year, including the importance of visual inspection, sampling and grain grading, testing for mycotoxins, grain cleaning, dust suppression and quality assurance of distillers grains.

Wet Start to Finish
The trouble started when planting got off to a slow start in 2009. Farmers were kept out of wet fields by cool temperatures and frequent rain showers. By May 10, corn planting in the 18 major corn states was only 48 percent complete—significantly behind normal, according to USDA's 2009 crop production summary.

That, in turn, delayed harvest. The final crop progress report came unusually late, on Dec. 22, says Anthony Prillaman, National Agricultural Statistics Service agricultural statistician. At that time, 95 percent of the U.S. corn crop was estimated to be harvested, with 5 percent remaining in the field. North Dakota, which was hit the hardest by a late planting season and delayed harvest, only had 68 percent of its corn crop harvested by Christmas.

With such a late harvest, it was very difficult to dry down that corn naturally. By November, field drying nearly stops completely, Bertels says. Corn that is more than 16 or 17 percent moisture needs heat to dry. If it doesn't, it quickly spoils. The high moisture corn coming in this year strained farmers and grain elevators that didn't have the needed drying capacity.

David Spickler, commodity manager for Blue Flint Ethanol, a 50 MMgy plant in Underwood, N.D., says the season started off with a mycotoxin scare that spooked distillers grains customers who demanded testing to prove toxin levels were under the acceptable limit. "Almost all of the corn we've brought in has had some sort of mold on it," he explains. Blue Flint put testing procedures in place very rapidly to meet the unexpected need. Fortunately, testing revealed the problem wasn't as bad as feared. Up through February, the plant hadn't found mycotoxin levels anywhere near the limit, Spickler says. "We're going to be diligent in testing," he adds. "We're still testing every day." In fact, they'll probably continue testing their corn for mycotoxins until the remainder of the 2009 corn crop is used.

The next concern is storage damage— something Blue Flint started seeing as early as late January. As the months progress, nobody is really sure what the corn will look like coming out of storage. "It's definitely a concern what this looks like when we get to May, June, July, August," he says.

Monitoring Stored Grain
With 65 percent of Iowa's corn supply going to ethanol production, Charlie Hurburgh, an agricultural engineer and grain storage expert, pays close attention to how high moisture corn has affected ethanol plants. The professor at Iowa State University runs the extension program on grain quality. In Iowa, as in most states, corn yields were good but moisture content was way up.

There just wasn't enough drying capacity to deal with all that wet corn. As a result, some people handled incoming corn well, while others fell flat on their faces. "There have been a number of instances of outdoor piles of corn spoiling, literally spoiling, turning black or brown," Hurburgh says.

In past years, 15 percent to 16 percent moisture was considered safe storage. This year, the best case scenario was drying corn to at least below 20 percent, putting it into storage with aeration and getting it cold to the point of freezing, he says. The thing to keep in mind is that if corn goes into storage with toxins on it, it will come out with toxins. "This year's corn has about half the storage life as normal corn," he tells EPM.

It's not so much of a problem in Iowa, but Hurburgh has heard stories of 10 times the FDA limit of vomitoxin on corn. This toxin got its name from what happens when livestock eats vomitoxin-contaminated grain. "A pig eats too much of it, guess what he does," he says.

All this adds up to a need for vigilance on the part of ethanol plants. The fact is, due to the value of corn, sellers have an incentive to blend bad corn into good corn. Hurburgh stresses that ethanol plants need to pay close attention to the quality of the corn coming into their plants—perhaps even using a third party grain grader. "Don't have your sloppiest guy doing the grading this year," he says. "If [ethanol plants] don't pay attention, I'll level with you, sellers of grain understand very quickly which plants are grading well, and which aren't."

Hurburgh actually sees this as a good thing for the health of the industry. The fact that there wasn't enough corn storage and drying capacity this year will prompt building and expansion. And, if the ethanol industry consistently demands good quality corn supply and rejects poor quality corn that will be good in the long run too. "That's going to force some changes all the way through the system," he says.

All Dried Up
So what happens when corn is aggressively dried down in a high moisture year? Will that have any effect on ethanol output? Researchers from Novozymes, Randy Deinhammer, staff scientist, and Anne Glud Hjulmand, director of research and development, described an experiment that started with whole corn dried under mild conditions. The corn was rehydrated to the moisture level farmers were finding in the fields this fall and then dried back down to 85 percent dry solids, representing typical corn coming into an ethanol plant.

The variable in the lab experiment was the temperature the corn was dried at, Deinhammer says. Corn was dried at 120 degrees Fahrenheit, 170 degrees and 230 degrees. After that, researchers turned the corn into ethanol in the lab, grinding it with a hammer mill and utilizing Novozymes enzymes in the conversion process. The researchers found as drying temperatures increased, the accessibility of starch in the ethanol decreased, resulting in reduced outputs of ethanol. For one thing, the amount of free sugar in the fermentation mash was reduced, he says. Secondly, the product started browning, which could also result in lowered ethanol yields. With corn dried at the highest temperature, at 230 degrees F., there was a 3 percent loss in ethanol yield. "The more aggressively you dry the corn, the more ethanol you lose," Hjulmand says.

The other variable in the experiment was the type of glucoamylase used. The Novozyme researchers did find that using a premium product did increase ethanol output, but could not overcome the entire loss. "It's something that is happened during the grain drying process," says Hjulmand. "You cannot repair it 100 percent." EP

Holly Jessen is associate editor of Ethanol Producer Magazine. Reach her at (701) 738-4946 or