Dry grind plants produce ethanol by grinding corn kernels into small particles; adding water, enzymes and ammonia; and putting the mix through a process wherein it is cooked, cooled, introduced to yeast and kept cool during fermentation until the ethanol produced by the fermentation evaporates into a vapor, which is collected and condensed into a liquid form. There is also a wet milling process for ethanol production, but wet mills carry higher costs and are much more complex.
Most ethanol in the United States is made from corn because it is in ample supply, but ethanol can be fermented from other sources of starch, such as wheat, grain sorghum, barley and potatoes. It also can be fermented from sugar crops.
Pure ethanol is a grain alcohol that finds uses as fuel in spark-ignition engines and as a key feedstock in the chemical industry. Blending ethanol with gasoline reduces the amount of gasoline in motor fuel. A common fuel blend for a standard fuel system consists of 10 percent ethanol and 90 percent gasoline, while vehicles with flex fuel modifications can handle blends containing 85 percent ethanol and 15 percent gasoline. Markets geographically distant from ethanol plants face higher prices, because ethanol is mainly transported by truck, rail and barge.