Advantages of using ethanol as fuel include its ability to serve as a renewable resource and its biodegradability in the event of spills, while disadvantages include a lower heat of combustion than petroleum and the possibility of environmental problems from the disposal of production fermentation liquors. As of 2015, approximately 2,000 ethanol fueling stations exist in the United States, mostly located in the Midwest.
The biodegradability advantage of ethanol is two-fold, in that its organic makeup naturally breaks down within roughly five days time, while petroleum does not. Ethanol burns more cleanly than petroleum, producing less carbon monoxide, carbon dioxide emissions and soot. The byproducts of corn-based ethanol are used in the food and beverage industry, as well as in agriculture, where they are used to feed cattle, crushed for corn oil and processed for biodiesel production.
Although there are environmental advantages to the use of ethanol, disadvantages include soil erosion, fertilizer run-off and deforestation. These issues stem from the large amounts of land that are needed to raise crops required for ethanol production. Ethanol also absorbs water, which can contaminate fuel supplies and complicate pipeline distribution, as well as shorten its shelf-life and decrease user mileage. As of 2015, the E85 blend of ethanol fuel is compatible with standard fuel vehicles, but higher blends of ethanol fuels are used in FlexFuel vehicles or those with modified engines.
The United States and Brazil are the major producers and consumers of ethanol fuel. Most ethanol fuel stations in the United States are located in the Midwest.