In 2006, more than 5 billion gallons of fuel ethanol were produced in the U.S. About 90% of fuel ethanol is produced from corn grain, with grain sorghum also being a significant feedstock.
Dry-grind is the most prevalent process for ethanol production in the U.S. and much of the current expansion of the industry uses this technology. Typically, 2.7 – 2.8 gallons of ethanol and 17 pounds of distiller’s dried grains and solubles (DDGS—used as livestock feed) are produced per bushel of corn.
Fuel ethanol is also produced using wet milling processes. Approximately 2.5 gallons of ethanol, 2.1 pounds of oil, and 13.8 pounds (dry mass) of corn gluten meal and corn gluten feed (used for livestock feed) are produced per bushel of corn.
Analysts generally agree that the ability to significantly increase ethanol production using corn grain is limited and that large increases will require the use of lignocellulose resources such as agricultural residues, grasses, and wood. This process is only beginning to be commercialized.
Ethanol production from sucrose (table sugar), while not practiced in the U.S., predominates in tropical regions with sugarcane production such as Brazil.