When an ethanol plant is operated in conjunction with a feedlot, air quality and contamination of groundwater can become a significant issue. Manure spreading may also cause soil contamination. For more information, see Intensive Livestock Operations (ILO's).>
If energy consumed in the production of ethanol is generated through the use of "dirty" fuels such as coal, the overall environmental impact is less positive. The net energy gain and environmental benefits of ethanol blended fuel are comprimised when "dirty" fuels are used to power any of the various stages of the production process.