Water resource requirements of corn-based ethanol

Ethanol derived from fermentation of corn is a very water-intensive product with water to ethanol mass ratios of 927 to 1178 and volumetric ratios of 1174 to 1492 for the major rainfed corn-growing U. S. states of Illinois and Iowa and the leading irrigated corn-growing state of Nebraska, respectively. Over 99% of water requirements are for growing corn feed stocks, with 99% of that amount in Illinois and Iowa, occurring as evapotranspiration of rainfall in corn fields, and 60% as evapotranspiration of applied irrigation water in Nebraska. As a rough measure of water quality impacts, 65.5 g N, 23.8 g P, and 1.03 g of pesticides are applied, and 4.8 kg of soil is eroded per liter of ethanol produced. These results add to knowledge on corn-based ethanol's low net energy balance and high carbon footprint by demonstrating the high water resource intensity of corn-based ethanol production.