USDA research area: More than fuel in ethanol process


The primary impediment to ethanol as an alternative fuel is the cost of production.

Even with the price of corn falling below its production cost, ethanol cannot be produced cheaply enough to compete with the cost of oil.

That’s why the cost of ethanol production has become a “crop” problem for USDA’s Agricultural Research Service.

Corn-Ethanol Process Cost Reduction is a major research project that has been going on since 1997 at the research service’s Eastern Regional Research Center in Wyndmoor, Pa. The laboratory develops new uses for agricultural commodities.

Secondary product. When ethanol first came on the scene in the 1980s, the wet mills first converted to produce ethanol previously produced high fructose corn syrup.

And as a byproduct of the process of steeping the corn to separate the high quality starch that could be processed into syrup, value co-products could also be produced.

In wet milling, a bushel of corn will produce 31.5 pounds of starch that can be turned into 33 pounds of sweetener, along with 12.4 pounds of 12 percent protein feed, 3 pounds of 60 percent gluten meal, and 1.5 pounds of corn oil.

Wet mills converted to ethanol production substitute the high fructose sweetener for 2.5 gallons of fuel ethanol, but the collateral production does not change.

In Minnesota. When Minnesota Corn Processors, a farmer-owned cooperative, agreed to support the “Minnesota model” of subsidizing ethanol production through the state legislature, it agreed to convert a portion of its sweetener operation to the production of ethanol.

Now Minnesota Corn Processors is the largest ethanol producing company in the country, with plants in Marshall, Minn., and Columbus, Neb., that have a capacity of 110 million gallons a year.

Of the wet mills processing plants now in operation, four out of nine are now producing ethanol rather than sweetener, according to Minnesota Corn Processors president Dan Thompson.

But it doesn’t have to be an either/or decision, he said. If the price of corn gets too high to make ethanol profitable, the facilities can switch back to sweetener.

In the current push to increase the production of fuel ethanol, however, no more of these large-scale wet milling production facilities are being constructed.

Each of the new ethanol production facilities that opened since 1999, and the 13 additional facilities now under construction are dry mill facilities. More than 60 percent of current production capacity is in dry mill plants.

Dry process. In a dry mill facility, rather than steeping the corn so that the auxiliary products can be separated to be processed separately, the corn is dry ground and then fermented as a whole product.

The mesh that is left after the ethanol has been distilled is known as “distillers grain.” This is being sold primarily as a high protein supplement for livestock feed.

A dry mill ethanol process yields the same 2.5 gallons of ethanol from a bushel of corn, with 17 pounds of distiller’s grain as the co-product.

Capturing potential. But the main research emphasis is reducing the cost of production in the dry process, and on capturing more of the co-product potential.

If wet milling is able to provide so much more value per bushel of corn processed, then why has dry milling become the process of choice?

The answer is in the cost and the size of production facilities. The new ethanol plants are being built by state-based farmer-owned cooperatives, and are sized at a 12 to 18 million-gallon capacity.

The 13 new plants under construction will result in a total of 330 million gallons of new production. For this sized facility, the cost of wet milling technology is prohibitive.

While a dry-mill plant can be constructed for $75 to $90 million, a wet mill plant of the same capacity would require closer to $250 to $300 million.

According to V.J. Singh, professor of agricultural engineering at the University of Illinois, who has been working on the technology of cost reduction at the research center at Wyndmoor, the problem is how to change the dry mill grind process to make its outcome more comparable to the wet mill process.

“We have been looking at ways to include some aspects of the wet mill process into the processing of dry grind,” he said, “and to get some of the same co-products from it without making the same capital investment.”

Pop out germ. One of the first results of the research, he said, was the development of a quick germ recovery process.

Wet milled corn is steeped in sulfides at 140 degrees for two days in order to get the kernel to break apart into its basic elements, he said.

But it has now been determined that the corn being used for ethanol production can be soaked in plain water for only a few hours before it is ground, and the germ will successfully pop right out.

That, he said, provides a high value co-product right at the start of process. And with the non-fermentable corn oil removed, more space is created in the fermentation chamber for the cornstarch that does ferment. Fracturing corn fiber, the hull, away from the remaining starch and protein has also been tackled, and a one-step process is now available to recover the fiber by changing the density of the slurry. Fiber is also non-fermentable, he said, further increasing the ethanol capacity of the production process.

Removing fiber will also increase the protein content of the distiller’s grain.

New fiber uses. From the fiber, Singh said researchers have developed a new kind of corn fiber oil that has been proven highly effective in lowering serum cholesterol. When fully developed, it should become an ever higher value co-product than the germ oil.

And from the defatted fiber, another researcher has created a heavy industrial gum that is expected to have several industrial uses.

Increased capacity. With all of these processes in place, Singh said a dry mill ethanol production facility would be able to increase its production capacity by several percentage points. The removal of the germ alone, he said, increases capacity by 2 percent. The fraction of the corn fiber by another 5 percent.

And the recovery of these additional co-products, he said, can offset the cost of ethanol production from about 4 cents to up to 10 cents per gallon.

The discovery of the potential to isolate, extract, and use corn zein is another project under way that is expected to create an additional high value co-product never before realized in the milling process.

In each of these cost reductions and those that are still on the drawing board, the cost of ethanol production gets closer and closer to being able to rival oil as a viable transportation fuel rather than just a 10 percent clean air additive to gasoline.

(You can contact Jackie Cummins at 1-800-837-3419, ext. 23, or by e-mail at


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