Ethanol In Your Gasoline Tank: The Pros And Cons

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Biofuel crops (photo: Texas A&M University biofuels research alliance)

Biofuel crops (photo: Texas A&M University biofuels research alliance)

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With flex-fuel cars that can run on E85 ethanol still a minority of the vehicles on sale, you might think ethanol isn't as important as some other future fuels.

But up to 10 percent of every gallon of gasoline you buy today is ethanol, and that proportion may rise to as much as 15 percent if gas stations migrate to so-called blender pumps.

Congress has mandated increasing volumes of ethanol in the U.S. fuel mix, though some analysts say the rules simply can't be met.

So what exactly are the benefits--and the problems--of using ethanol as a vehicle fuel, in whatever proportion?

Click the links to check out the pros and cons of both hybrid vehicles and diesel cars.


There are many reasons to support a move away from fossil fuels, but one of the most compelling is to improve U.S. energy independence.

Though the U.S. has its own reserves of crude oil, large amounts are still bought in from politically unstable regions of the Middle East.

Reducing the use of a fuel that could suddenly dry up through trade restrictions or suddenly cost more is very much a priority, and ethanol--which is mostly produced domestically--is one way of hedging against those threats.

Large swathes of countryside, particularly in the Midwest, are set aside for the corn used as a feedstock for refining ethanol.

As demand increases, that has a positive effect on jobs. More ethanol production in the U.S. means more jobs for U.S. citizens.

Ethanol is also greener than gasoline, because corn and other plants absorb carbon dioxide from the atmosphere as they grow. The fuel still releases CO2 when you burn it, but the net increase is lower.

Potentially, ethanol is also tailor-made for newer, higher-compression engines.

A high compression ratio usually requires higher octane levels in the fuel to prevent pre-ignition, a condition that puts high levels of stress on an engine. Ethanol has a higher octane rating than regular gasoline, so it's suited to these efficient, high-compression designs.

Lastly, using ethanol as a small portion of the gasoline blend offers adaptability. Any car since 1980 has been designed to handle up to 10 percent ethanol in the gasoline, letting you run that percentage of your miles on a domestic fuel rather than irreplaceable fossil fuels.

But to go with the Pros, there are also some Cons (see next page).

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Comments (7)
  1. In some classic cars the gas tank isn't sealed and ethanol absorbs moisture so you can end up with water in your fuel system. This affects carburetors, seals, Ect. This and the potential issues in some new cars I think makes deluting gasoline a stupid waste of time. It's only being done to stretch our gas supply, it's just a lazy way of getting out of making real changes. It's like adding water to your orange juice just so you can avoid a trip to the market.

  2. It also reduce your MPG by 5-7miles.

  3. Ethanol in gasoline is in my opinion an interim solution. Other alternatives such as Natural Gas and Vegie oil are also worthwhile ideas to consider. Ultimately, I believe the future is to head into the Electric direction.

  4. Ethanol sucks. its just that simple. it increases costs it increase pollution and it increases maintenance costs.

    I have just a "few" cars.

    1996 Plymouth Voyager Minivan
    E0 28mpg E10 20mpg

    1992 Ford CLubwagon
    E0 19-21mpg E10 13-17mpg

    1988 Jeep Cherokee Lifted 31" tires
    E0 24mpg E10 19mpg

    1988 Cherokee (no lift second cherokee)
    E0 21mpg E10 17mpg.

    1994 Geo Metro XFI
    E0 58mpg E10 50mpg

    OH and every single one of these cars save the metro needed a new FUEL PUMP within 6 months of the switch from E0 to E10

    and so did my pops windstar and lumina apv and so did my mom's lumina. all needed new fuel piumps. we changed 7 fuel pumps when we switch to E10.

    E10 blows not because it has ethanol but because its mandatory. I don't have a choice.

  5. in fact E10 is why I had to give up the comfort and convenience of my minivan and buy the Geo Metro. I drive 40,000 miles a year. that means it cost me roughly $5000 A YEAR in gasoline about 1428.5 gallons of fuel.

    with E10 my costs skyrocketed to $7000 a year (2000 gallons) which I flat out could not afford.

    this forced me to buy the 94 Geo metro as I could NOT AFFORD the $2000 increase in fuel costs as a DIRECT result of E10 propagation where I have NO CHOICE.

    the Geo metro gets average of 50mpg with E10 costing me $2800 a year for 800 gallons.

    its far far less comfortable and has NO air conditioning. it sucks but better than $7k a year in fuel as a result of E10.


  7. Probably just me but the cons listed far out weigh the alleged pros. Does the claim of less polution take in to the account the extra fuel needed for the same amount of work? I saw no mention of higher food prices. What about the fuel it takes to grow the corn in the first place? How much extra energy is being created versus other means of harvesting energy (solar?). Ethanol is a tax on drivers and another farm subsidy.

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