The following is an excerpt from Sustainable Ethanol: Biofuels, Biorefineries, Cellulosic Biomass, Flex-Fuel Vehicles, and Sustainable Farming for Energy Independence
Ethanol Questions and Answers
● What is ethanol fuel?
Ethanol fuel is an alcohol used in internal combustion engines. In North America, it is usually sold blended with gasoline as E10 or E85.
● What is the difference between E10 and E85?
E10 is an automotive fuel made up of about 10% ethanol and 90% gasoline. Modern cars can use it without modification. E10 is widely available in North America.
E85 is made up of approximately 85% ethanol and 15% gasoline. It can be used only in vehicles equipped for higher levels of ethanol, such as flex-fuel vehicles. Find your nearest E85 pump by visiting the National Ethanol Vehicle Coalition web site: www.e85fuel.com.
A U.S. DOE tool locates all kinds of alternative fuels:
● What is a flex-fuel vehicle?
In North America, “flex-fuel vehicle” (FFV) usually refers to an automobile designed to run on standard gasoline, E85, or any combination of the two. In other words, a flex-fuel vehicle runs fine on anywhere from 0% to 85% ethanol. Many FFVs available in Brazil can run on 100% ethanol (see Chapter 5). The National Ethanol Vehicle Coalition maintains a list of FFVs at www.e85fuel.com.
● Will ethanol hurt my car?
Most manufacturers specifically approve the use of E10. If your car is very old or antique, you may need ethanol-free gasoline. E85 should be used only in vehicles specifically designed for it, commonly known as flex-fuel vehicles (see Chapter 5).
● Will ethanol reduce miles per gallon?
Studies by the EPA and American Coalition for Ethanol indicate E10 reduces fuel economy for some car models and improves it for others. Overall, the results are better than you would expect based on energy content alone.
Using E85 in flex-fuel vehicles (FFVs) currently available in North America causes a significant loss in fuel economy. This is due to ethanol’s lower energy density. Future FFV models could get better fuel economy by taking advantage of ethanol’s knock-suppression ability (see Chapters 5 and 6). Look up EPA fuel economy data for FFVs at www.fueleconomy.gov.
The EPA and DOE provide an online tool for calculating the cost of using E85 and gasoline in your region and using your particular FFV. Click the cost calculator link at
● Is ethanol good for the environment?
Many researchers believe ethanol is better for the environment than the gasoline it replaces. Advances in production and use efficiency are improving that advantage (see Chapter 4).
● Isn’t ethanol really non-renewable because of how much fossil energy it takes to make it?
A few studies conclude fossil fuel inputs for ethanol production are greater than the energy derived from ethanol use. Most studies, however, show a net gain because of solar energy collected by plants. Thanks to advances in farming and production efficiency, ethanol’s net energy balance is getting better (see Chapter 10).
● Can the U.S. totally replace gasoline with ethanol in the near future?
Not unless we cut back drastically on our energy use! Ethanol can, however, be a significant factor in reducing our dependence on imported oil. Other renewable solutions like butanol, biodiesel, biogas, direct solar, and wind will also be important. The U.S. Department of Energy predicts “alternative technologies” could displace the equivalent of 4% of projected U.S. annual consumption of petroleum products by 2015, and 34% in the 2025–2030 timeframe.
● Is ethanol made from anything other than corn?
Ethanol can be made from any sugar. This may be in the form of simple sugars from sugar cane, sweet sorghum, and sugar beets. Starches from crops like corn, wheat, and milo can be converted to simple sugars for ethanol production as well. Ethanol and other biofuels can also be made from cellulose and hemicellulose broken down into sugars. Cellulose and hemicellulose can be found in organic municipal waste, crop residues, trees, or various energy crops (see Chapters 8 and 9).
This Q & A is from Sustainable Ethanol, available at:
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. United States Government Accountability Office, CRUDE OIL: Uncertainty about Future Oil Supply Makes It Important to Develop a Strategy for Addressing a Peak and Decline in Oil Production, February 2007, http://www.gao.gov/new.items/d07283.pdf.