Founded in 2004, Green Plains Renewable Energy, Inc. engages in the construction and operation of dry mill, fuel grade ethanol production facilities in the United States. It produces ethanol by the fermentation of sugars found in grains and other biomass. The company also produces distillers grains, an animal feed supplement obtained as a by-product of the ethanol production process. It is operating an ethanol plant, located in Shenandoah, Iowa; and constructing another plant in northwestern Iowa near the town of Superior.