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Transportation & Fuel Source Technology


E85 Ethanol Offers Cleaner Emissions, but Poorer Fuel Economy


Tests and an investigation by Consumer Reports conclude that E85 ethanol will cost consumers more money than gasoline and that there are concerns about whether the government's support of flexible fuel vehicles is really helping the U.S. achieve energy independence.

Findings from CR's special report include:
  • E85, which is 85 percent ethanol, emits less smog-producing pollutants than gasoline, but provides fewer miles per gallon, costs more, and is hard to find outside the Midwest.
  • Government support for flexible-fuel vehicles, which can run on either E85 or gasoline, is indirectly causing more gasoline consumption rather than less.
  • Blended with gasoline, ethanol has the potential to fill a significant minority of future U.S. transportation fuel needs.
To see how E85 ethanol stacks up against gasoline, Consumer Reports put one of its test vehicles, a 2007 Chevrolet Tahoe Flexible-Fuel Vehicle (FFV) through an array of fuel economy, acceleration, and emissions tests.

Overall fuel economy on the Tahoe dropped from an already low 14 mpg overall to 10. In highway driving, gas mileage decreased from 21 to 15 mpg; in city driving, it dropped from 9 mpg to 7. You could expect a similar decrease in gas mileage in any current flex fuel vehicle because ethanol has a lower energy content than gasoline-75,670 British thermal units (BTUs) per gallon instead of 115,400 for gasoline, according to the National Highway Traffic Safety Administration. As a result, you have to burn more fuel to generate the same amount of energy.

With the retail pump price of E85 averaging $2.91 per gallon in August, according to the Oil Price Information Service, a 27 percent fuel-economy penalty means drivers would have paid an average of $3.99 for the energy equivalent of a gallon of gasoline.

When Consumer Reports calculated the Tahoe's driving range, it found that it decreased to about 300 miles on a full tank of E85 compared with about 440 on gasoline. So, motorists using E85 would have to fill up more often.

Most drivers in the country have no access to E85, even if they want it, because it is primarily sold in the upper Midwest; most of the ethanol in the U.S. is made from corn, and that's where the cornfields and ethanol production facilities are located. There are only about 800 gas stations-out of 176,000 nationwide-that sell E85 to the public.

When Consumer Reports took its Tahoe to a state-certified emissions-test facility in Connecticut and had a standard emissions test performed, it found a significant decrease in smog-forming oxides of nitrogen when using E85.

Despite the scarcity of E85, the Big Three domestic auto manufacturers have built more than 5 million FFVs since the late '90s, and that number will increase by about 1 million this year.

A strong motivation for that is that the government credits FFVs that burn E85 with about two-thirds more fuel economy than they actually get using gasoline, even though the vast majority may never run on E85. This allows automakers to build more large, gas-guzzling vehicles than they otherwise could under Corporate Average Fuel Economy rules. As a result, these credits have increased annual U.S. gasoline consumption by about 1 percent, or 1.2 billion gallons, according to a 2005 study by the Union for Concerned Scientists.

From an alternative-energy perspective, it doesn't matter whether ethanol is blended as E85 or in lower mixes such as E10 (a 10/90 ethanol/gasoline mixture) that all cars can burn; a given amount of ethanol still goes just as far in reducing demand for gasoline. Experts agree that the maximum amount of ethanol you can get from corn in the U.S. is about 15 billion gallons. But scientists are working on producing ethanol from other plant material, called cellulose, which could increase this capacity by as much as 45 billion gallons. (For comparison's sake, the U.S. burned 140 billion gallons of gasoline in 2005.)

The important backdrop to the ethanol debate, of course, is that petroleum is a finite resource that's rapidly being depleted. Government scientists are planning for a day when world oil production peaks and begins to slow. They say the country must begin planning for alternatives 20 years before that peak. Today ethanol is receiving their attention because it requires fewer technological breakthroughs and less infrastructure development than batteries or fuel cells, and by including cellulose, its capacity can exceed that of biodiesel.

Consumer Reports is one of the most trusted sources for information and advice on consumer products and services. It conducts the most comprehensive auto-test program of any U.S. publication or Website; the magazine's auto experts have decades of experience in driving, testing, and reporting on cars. To subscribe to Consumer Reports, call 1-800-234-1645. Information and articles from the magazine can be accessed online at http://www.ConsumerReports.org.





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