How is ethanol currently produced from corn?
In the United States, ethanol is produced primarily from starch in corn kernels. Most of the 4 billion gallons of ethanol produced in 2005 came from 13% of the U.S. corn crop (1.43 billion bushels of corn grain). When corn is harvested, the kernels make up about half of the above-ground biomass, and corn stover (e.g., stalks, leaves, cobs, husks) makes up the other half. Ethanol production from corn grain involves one of two different processes: Wet milling or dry milling. In wet milling, the corn is soaked in water or dilute acid to separate the grain into its component parts (e.g., starch, protein, germ, oil, kernel fibers) before converting the starch to sugars that are then fermented to ethanol. In dry milling, the kernels are ground into a fine powder and processed without fractionating the grain into its component parts. Most ethanol comes from dry milling. Key steps in the dry mill ethanol-production process include: • Milling. Corn kernels are ground into a fine powder called “
