The search for a perfect ethanol corn

Accessible starch is key to the ethanol production success of a particular hybrid
By Tom Bryan | September 01, 2002
The year is 2012, and a farmer-owned ethanol plant in South Dakota - one of 10 in the state - is producing 3.2 gallons of ethanol per bushel of corn, and delivering 130 mmgy to the 10 billion gallon U.S. ethanol market.

Wishful thinking, maybe, but this futuristic scenario could become reality in less than a decade if crop scientists continue to deliver hybrids that yield more and more ethanol. Researchers are calling it a "search for the perfect ethanol corn," and it's a quest that is only beginning to unfold.

At the forefront of this science are the world's leading seed companies, such as Pioneer and Monsanto, which quietly pursue new corn hybrids created to boost ethanol production. Working cooperatively with the research arms of these corporations, researchers such as Dr. Bruce Dien, Dr. Rodney Bothast, and others are shedding new light on the mysteries of corn-ethanol research.

'Evolutionary vs. revolutionary'
In a sense, seed companies have been tailoring corn hybrids for ethanol production for decades by increasing the corn and starch yields, thereby, keeping feedstock costs down, Dien told EPM.

"The science has been more evolutionary than revolutionary," he explained.

Despite the increased use of corn for ethanol production in the U.S., seed companies have not rushed to market corn cultivars specifically tailored for ethanol production. This is changing, however, as both Pioneer and Monsanto are currently working closely with ethanol producers in the search for a better ethanol corn.

Pioneer has a Crop Genetics Research Group that has been focused on dry-grind ethanol processes for several years, while Monsanto has also established a Corn Ethanol Research & Development program to improve the genetics of corn in order to help lower ethanol's cost per gallon.

"Monsanto's Corn Ethanol program is employing grain analytics, advanced breeding, and biotechnology to develop and identify the perfect ethanol corn hybrid," said Matt Kraus, communications lead for Monsanto's ethanol division. "As part of the new Monsanto pledge, our corn ethanol program is dedicated to bringing additional economic benefits to growers and, because the majority of dry mill ethanol plants are partially owned by growers, an increase in ethanol yield would result in a significant return on investment to growers."

Doug Haefele, a senior research scientist with Pioneer, said, "I think that we've been very active in bringing knowledge about the difference corn genetics can make to the industry. But most importantly, we've started by working in a cooperative fashion with the key customers involved - dry grind ethanol producers and corn growers - in order to fully understand the market issues involved."

Still, both companies told EPM, progress has been limited by low demand on the part of ethanol producers and growers, and scientific vigilance on the side of seed companies and researchers.

"We are very conservative in making claims for corn hybrids until we have sufficient data to convince our industry collaborators and ourselves that the value of Pioneer HTF hybrids has been demonstrated," Haefele said. "Since the successful completion of our most recent commercial-scale testing earlier this year, we have begun making this information available to producers."

Likewise, Kraus said, Monsanto has simply been waiting for the right opportunity to market corn hybrids made for ethanol production.

"Historically, breeders and seed companies have bred corn for (harvest) yield, not for quality of grain composition tailored for ethanol production," Kraus explained. "Therefore, as a feedstock, all corn has been perceived to be the same by growers and ethanol plant managers. That is corn iscorn is corn. Seed companies, including Monsanto, now recognize the recent, current, and future boom in expansion of the ethanol industry, and that the opportunity to optimize the genetics of the feedstock and lower ethanol production costs is a win-win for the farmer, ethanol plant, and seed company."

Agreeing with Haefele and Kraus, Dien said the demand for corn hybrids tailored for ethanol production may be most tempting to members of farmer-owned ethanol cooperatives - grower-investors with a stake in the ethanol production.

"The market is conservative," Dien said, "I think the key will be convincing ethanol producers that it is economically worthwhile to (encourage) farmers to grow particular hybrids. . .In terms of ethanol production, of course, the best corn will be that which has the lowest net cost and yields the most ethanol. In the future, it might be quite possible that producers will contract for different hybrids optimized for different marketing strategies."

Starch content not everything
Bothast and Dien, along with Dr. Steve Eckoff of the University of Illinois, and other researchers, recently published a study entitled Fate of Bt Protein and Influence of Corn Hybrid on Ethanol Production. Aside from determining the fate of Bt (Bacillus thuringiensis) when Bt-modified corn is processed into ethanol, the study also offered preliminary findings that challenge the common assumption that corn hybrids with high starch contents yield the most ethanol.

"The take home message (was) that not all starches are created equal," Bothast said.

In the study, scientists fermented corn samples from five hybrids containing between 68 and 72 percent starch. Using a standard method, they measured the hybrids' fermentation efficiency (CE). This refers to how much of the total starch actually breaks down into the glucose sugar that gives rise to ethanol.

Representative of the study's findings are the ethanol yields and CE rating for hybrid A and hybrid C. Hybrid A, with a starch content of 68 percent, yielded 2.73 gallons of ethanol per bushel, with a CE rating of 92 percent. Hybrid C contained 72 percent starch, and yielded 2.83 gallons of ethanol per bushel. But its lower CE rating, 90 percent, meant that less of that starch actually converted into sugar, the researchers say.

"The hybrid in our study that gave the highest ethanol yield did not contain the highest starch content," Dien told EPM. "This means that while the maximum possible ethanol yield is determined by starch content, actual ethanol yield is not perfectly correlated to this factor."

The researchers were not completely surprised by the results because it is widely known that the amount of starch found in distillers grains routinely varies - meaning that the starch in some hybrids is not completely available - or digestable during fermentation.

Still, the researchers said, the findings are considered preliminary since the five hybrids they tested are a small sampling of the hundreds now grown commercially. They also want to further verify the methods by which they obtained their results, as the research eventually could provide commercial seed companies with a protocol they could use in their corn breeding programs.

"I think a more detailed study about the mechanism behind what determines starch available for hydrolysis would be interesting," Dien said. "We are developing a better laboratory scale protocol for modeling the industrial dry grind process that includes a jet cooker. In dry-grind facilities the corn is liquefied by mixing it with direct steam in a jet cooker. We think that using a jet cooker will allow us to better predict what would happen at an actual plant. Ideally, once the list of hybrids has been shortened; a pilot plant run could be used to further verify the choice of hybrids."

So the question remains: What actually makes a hybrid's starch breakdown into simple sugars for easy fermentation? Why does starch availability differ among hybrids?

"That's the million-dollar question," Bothast said. "It could be due to the environment in which the corn is grown, or the DNA comprising its genes and their subsequent effect on the composition of the corn itself."

Dien added, "We really don't know, but it might have to do with the starch structure, or it could also depend on how the starch is bound to the fiber portion, or there could be other explanations as well. . . It is a question that we will be examining in the future."

How soon will it happen?
If it is, as scientists are beginning to prove, possible for breeders to create corn hybrids precisely tailored for ethanol production, when will this corn be available? Who will grow it? And how will it perform for other uses?

"It is realistic to assume that our efforts through grain analytics and advanced breeding techniques are viable - near-term and mid-term - approaches to deliver significant increases in ethanol production," said Brad Krohn, Monsanto's technical lead on ethanol projects.

What will it mean to an ethanol plant's bottom line? According to Pioneer, the exact impact of this on the profitability of a given facility is difficult to calculate without knowledge of the input costs, selling prices, and production constraints within which that facility operates. Still, producers can make their own projections based on the increases in yield new corn may offer.

"Our commercial-scale testing indicates that, for those facilities that have access to Pioneer HTF products, there could be an increase in ethanol yield of up to 4 percent," Haefele said.

Monsanto was willing to guess that increasing ethanol yields by five percent could result in as much as $2 million in additional new profit for a typical 40 mmgy dry mill.

"However, there are numerous variables to consider such when determining the value such as kinetics, DDGS quantity and quality, processing improvement, etc.," Krohn said. "Another important variable to consider is that when a plant chooses to utilize HFC hybrids not only are they utilizing higher fermenting hybrids but they also will be reducing or eliminating the hybrids that perform poorly in fermentations system which pulls the plant production yields average down. It is all about improving the feedstock quality."

Regional variances, availability
The same ethanol corn hybrids will be available to all ethanol producers, but not all hybrids are suitable for planting in all parts of the country. Growers know in detail what genetics work on their farm. Since traditional measures of productivity (bu/acre) remain the largest genetic influence on profitability, it's important that growers select hybrids that bring the greatest value to each acre of their land. Furthermore, the hybrids that work best for each ethanol plant will be dependent on environment, location, and relative maturity zone.

Any potential drawbacks?
But what are the potential drawbacks of creating this ethanol corn hybrid? For example, will breeding corn for ethanol yield make the coproducts less suitable for other uses (e.g., animal feed and carbon dioxide for soda production)?

"Theoretically, it defies the laws of physics that carbon dioxide captured from fermentation contains any detectable level of transgenic protein or DNA," Krohn said. "We know of no study that has been able to detect Bt protein or DNA in carbon dioxide. Therefore, this concern is largely unwarranted."

Furthermore, the researchers said, even if Bt was detectable in coproducts, the products are safe for human consumption and have been through multiple regulatory processes.

"We realize that DDGS may possibly contain detectable amounts of transgenic protein or DNA.," Krohn said. "However, the vast majority of DDGS is not exported, and the market potential for DDGS as a domestic animal feed is very far from being saturated, but rather represents a huge opportunity for beef, poultry, and swine feedlots, as well as eastern dairy feedlots."