Corn

Corn is presently the benchmark feedstock for biofuel production in the United States. Its availability and starch content make it the yardstick by which all other feedstocks are measured in the U.S. In particular, the corn grown in the Midwest has proven valuable for that region's ethanol production. Most of the corn grown in the U.S. is grown for animal feed. Only the starch content of the corn kernel is typically used for biofuels production. The remainder - protein, fiber and oil - is called distillers grains, or if dried, it is called distillers dried grains or DDGs. DDGs are used in animal feed mixes. Another key reason why corn has been an effective feedstock for the United States is because it stores and ships well. Feedstock availability year-round is key to large-scale biofuels production.

Cellulosic corn ethanol

Because yellow dent corn? is grown in extremely large quantities, it also lends itself to having its waste after harvesting being turned into cellulosic ethanol. The waste is the stover, stalks, leaves, and cobs that remain in corn fields after grain harvest. DuPont Danisco? is looking at a corn cob cellulosic ethanol? model as a bridging technology to switchgrass in Tennessee. (Switchgrass is not yet grown in sufficiently large volumes.)

Currently, 90 percent of corn stover is left unused in the field. Corn stover is about 70 percent cellulose and hemicellulose, complex carbohydrates? that can be used in biofuel production. There is reason for some pause: removing all stover may affect soil erosion and nutrient gain. Therefore, it is important to find the right balance of how much stover to remove.

Corn as a feedstock in the Midwest

The average corn yield in the 2009 season was 163 bushels per acre - up from 101 bushels in 1978. Higher yields have been achieved through better technology and farming practices, not through increased use of fertilizers, pesticides and other inputs. Here are improvements since 1978¹:
* A 27% decrease in irrigation water use per bushel
* A 30% reduction in greenhouse gas emissions per bushel
* A 37% decrease in the land required per bushel
* A 37% decrease in energy required per bushel
* A 69% reduction in soil loss per bushel

The following is from the Center for Transportation Research at the Argonne National Laboratory?² showing production improvements over the past five years:
* Corn ethanol production efficiency has decreased water use by 27%
* A 22% reduction in fossil energy use
* A 7% increase in the amount of ethanol produced per bushel of grain

In 2009, US farmers produced the largest corn and soybean crops on record³. NASS plans to resurvey corn and soybean producers in states with late harvests, as these numbers are expected to increase further.
* Corn production is 13.2 billion bushels, 1 percent above the previous record of 13 billion
bushels set in 2007, and 9 percent higher than 2008. Corn yields reached an all-time high
in 2009 at 165.2 bushels per acre, eclipsing the previous record of 160.3 bushels per acre
set in 2004.

Corn as a feedstock in North Carolina

Corn is grown in North Carolina, but not in the quantities in the Midwest and because of the limited quantity, cannot be an economically viable local feedstock. Corn may play a support role as part of a range of starch and sugar agricultural feedstocks for a first generation ethanol facility in North Carolina.

External links and references

¹ These numbers from the Renewable Fuels Association as quoted, here:
_² The full study by the Argonne National Laboratory is here:

³ According to the Crop Production 2009 Summary released by the USDA’s National Agricultural Statistics Service, NASS. The summary is here:

Renewable Fuels Association
Argonne National Laboratory