1. Autos
Send to a Friend via Email

Your suggestion is on its way!

An email with a link to:


was emailed to:

Thanks for sharing About.com with others!

Quiz Yourself on Ethanol Facts

How Savvy Are You About This Common Renewable Fuel?


Ethanol pump

Ethanol has been faulted for reduced engine performance despite its octane enhancement.

U.S. Department of Energy

Ethanol has become so commonplace that most of us don't give its existance in the blended fuel we use a second thought at the pump. Yet there are a lot of misconceptions about ethanol and ethanol production. Can you distinguish fact from the myths below on ethanol?

Increased use of ethanol is going to deplete the supply of corn.

Myth. When food and feed prices took an upswing at about the same time that the ethanol indusry took off, many pointed a finger at ethanol. But it's much more likely that other factors - including widespread flooding - had much more to do with the jump in prices. The amount of corn used every year to produce ethanol is actually only about 5% to 7% of the total current annual production of the crop. In addition, production of ethanol results in distillers grains, which has grown into a major animal feed. But due at least in part to continued concerns over the use of corn, current research and innovation is focusing on alternative biomass products like woodpulp, switchgrass, corn stover and even municipal waste.

It takes more energy to produce ethanol than the energy ethanol provides.

Myth. This is an argument that continues to be made by ethanol opponents, but the facts don't back up the statement, and that's true whether the ethanol in question is derived from corn or from some other feedstock, like switchgrass. The ethanol fuel cycle generates more energy than it consumes and has been growing in its efficiency over the past decade. There are several reasons for this, including higher yielding corn hybrids, precision farming, and greater adoption of conservation measures like no-till planting, not to mention rapid advances in fuel conversion technology. Although both corn- and biomass-based ethanol have been shown to use less energy and producer fewer greenhouse gases, ethanol from non-grain sources posts the best efficiencies, primarily because it requires much fewer inputs. According to a fuel cycle evaluation conducted by the U.S. Department of Energy, the fuel cycle of ethanol produced from biomass feedstocks generates 6.8 Btu for every Btu of fossil energy consumed. The production of reformulated gasoline, which is used in many urban areas of our country, generates only 0.79 Btu of fuel energy for every Btu of fossil energy consumed, according to the study.

Ethanol significantly reduces harmful engine emissions.

Fact. According to the U.S. Environmental Protection Agency, about one-third of carbon dioxide emissions in the country come from the production and use of transportation fuels. But if 4 billion gallons of ethanol replaced petroleum use, about 26 million metric tons of carbon dioxide emissions could be eilminated. How does this happen? The answer is two-part. First, the plants the are grown to produce ethanol actually absorb carbon dioxide during growth, reducing the presence of this greenhouse gas. Secondly, and perhaps better known, ethanol reduces carbon monoxide produced by gasoline combustion. Ethanol is an oxygenate and so it causes more complete combustion, lower the amount of harmful greenhouse gases produced. The National Center for Vehicle Emissions Control and Safety at Colorado State University has documented a 25% to 30% reduction in carbon monoxide emissions when vehicles are fueld with a 10% blend of ethanol.

Ethanol performs in engines as well as gasoline.

Fact...and Myth. It depends on your measurement of performance. A primary advantage of ethanol for engine performance is its octane enhancement: a 10% blend of ethanol in gasoline raises the octane number by 2.5 points. When ethanol first came into use, underground storage tanks were not of the same quality and therefore, water would attach itself to fuel alcohol, later freezing up the fuel line and affecting performance. But this is no longer the case. On the contrary, ethanol can now stop small amounts of water from collecting in your vehicle's fuel system. On the other hand, ethanol does contain less energy per unit volume than dos unblended gasoline, which is why its critics have a true argument when it comes to miles per gallon, which are typically reduced with a 10% ethanol blend. It will be interesting to see how the industry, mindful of this issue, overcomes the the problem in the future, possibly falling to automakers to design engines better able to take advantage of the high-octane benefits of ethanol blends without the pain of reduced fuel efficiency.

  1. About.com
  2. Autos
  3. Hybrid Cars & Alt Fuels
  4. Alternative Fuels 101
  5. Ethanol Mythbuster - Fact Versus Fiction on Ethanol

©2014 About.com. All rights reserved.