• Apr 11th 2011 at 2:02PM
  • 18
When gassing up your vehicle, you've likely noticed a sticker on the pump that reads "this fuel may contain up to ten percent ethanol" or something similar. Have you ever asked yourself, "what's up with this ethanol in gasoline?" Well, get ready 'cause we've dug up an answer.

Way back in 1992, the U.S. government amended the Clean Air Act to include the requirement of oxygenated gasoline, which means a minimum oxygen content of two percent (by weight) for reformulated gas. One of the oxygenates used back then was methyl tert-butyl ether (MTBE). In 1995, California discovered that trace amounts of the dangerous MTBE was contaminating drinking water. Ethanol (a biofuel commonly derived from corn), which was thought to be safer than MTBE, was considered as a replacement oxygenate and, with strong backing from the agricultural industry here in the States, the biofuel slowly took over.

So, now that we know why most gasoline has some ethanol in it. The next logical question is: do you need to worry? The answer is a qualified no. Modern cars and trucks can capably burn E10 (a blend of 10 percent ethanol and 90 percent gasoline) and some automobiles should not have any problems running E15, a gasoline blend that will likely start to appear at fueling depots across the nation this summer. There is still a debate going on about E15, but any pump carrying that fuel should be clearly labeled. For more on ethanol, check out this Greenlings article in our archives.

Note: To mark the 41st anniversary of Earth Day* this year on April 22nd, we're running a series called Countdown to Earth Day that we want to be very welcoming to new readers, both in topic and tone. We'll be returning to our Greenlings series for inspiration here, and if you have friends who you'd like to introduce to AutoblogGreen, perhaps these introductory posts and the coming "holiday" will be the spark to light their green car fire interest.

[Image: futureatlas.com - C.C. License 2.0]

*Ironically, the apparent traditional gift for a 41st anniversary is land. Since land – earth – is something we can't easily create, how about we give ourselves the gift of stewardship of the land this Earth Day.


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  • 18 Comments
      • 7 Months Ago
      The amount of ethanol required to produce RFG is only 5.79%. Above that level, there is no benefit in emissions. And if you are not in an area that requires RFG, the presence of ethanol is not due to that.

      E10 and any other mixes over 5.79% are produced in order to meet federal blending mandates. These are currently 13 Billion gallons a year, 40% of the corn crop, which requires more than the RFG percentage of our gasoline to be ethanol.
      • 7 Months Ago
      I've been burning 10% ethanol in my cars for more than 15 years. It always amuses me to see the consternation with which it's greeted in new areas, and all the people claiming that their car doesn't perform. I heard it all here... and then, as soon as people stopped thinking about it, the complaints disappeared. I've run vehicles as diverse as my '72 Mustang Cobra Mach 1, a '79 RX-7, various small hatchbacks, a decrepit Datsun pickup, and a '04 Prius. Careful bookkeeping did see as much as a 5% drop in mileage in the older cars... but then, they're also pretty old cars and I can't promise that the difference wasn't at least partly aging (the ponies have leaked from my old pony car at a pretty steady rate).

      Performance wise, I didn't drop so much as a tenth of a second at the changeover. And if there have been any maintenance issues over that time, they haven't been noticed. I did have to put a new set of seals put in the RX-7 engine recently, but I think that's probably true of anyone trying to keep up a 30 year old rotary, no matter what the fuel.
        • 7 Months Ago
        Aside from the fact that it takes more energy to create corn based ethanol than you get out of it, the E 10 blend does not deliver the same fuel economy as the unblended product in virtually all applications...it has less energy.

        Corn based ethanol is poring money down a rat hole.
        • 7 Months Ago
        RB, even enemies of corn ethanol admit you get more energy out of it than you put in 1.3 per 1. The most relevant metric is not "energy" though but petroleum, and the figure there is dramatic - 10 and even 20 units of ethanol per unit of petroleum.
        • 7 Months Ago
        @RB
        Stop using the bogus Pimentel and Patzek study which is the only study that said there was a negative energy return all other studies have shown a positive return, although it was the main study used by most media. FYI Patzek is the chairmen of the UC Oil Consortium.
          • 7 Months Ago
          RB and Carney: I'm not sure what studies you two are talking about, but how about a Mechanical Engineer weighs in on the subject. Ethanol has less energy density than petrolium. Period. It is a fact that is not negotiable and is known by anyone who paid attention in high school chemistry class. Where it may appear that an engine produces more power from ethanol is that ethanol raises the octane rating of the fuel, so the compression ratio can be raised, or superchargers and turbochargers can be run at a higher boost. If you don't retune the engine to run on the different fuel, you WILL see a drop in mileage, power output or both. Granted, with only 10% ethanol the difference may not even be noticable to the average driver (especially with how detuned most cars are these days). The four biggest problems I have with ethanol in gasoline are: 1. It makes the fuel more caustic. Even if you replace the rubber seals in the fuel system of an older car, or have a new enough car not to need to do so, it will still wear on the metal parts faster than gasoline would. The metal parts are actually wearing a bit faster because of the more caustic fuel. It takes just as much resources to make the car, and because of the fuel used the car will now not last as long. Also, everyone knows that older, higher mileage cars create more pollution because they are running less efficiently. Because the engine is wearing faster, this is also accelerated. 2. It costs us money. I have seen so many different figures that I am not going to tell you how many gallons of diesel or natural gas or whatever it takes to make the stuff. The fact is it takes energy, time, materials and labor to reformulate gasoline, and drives the price at the pump up as a result. In fact, if the government weren't subsidizing it (which we pay for anyway through taxes), it would cost a lot more than it does. On top of this, it is creating a spike in food prices and in the prices of some organic-based products that are made from vegetation. The two reasons for this are that many farmers are planting corn instead of other crops (they get more money for it with the subsidies), and enough corn is being used for ethanol that what is left is less than was being grown before the reformulated gas mandates. Supply and demand on both counts. 3. The government isn't n get more money for ti with the subsidies. going about it logically. Can anyone say "switchgrass"? There are other things besides corn that are at least as good, or better, sources for ethanol. By better, I mean more ethanol production with less required labor and other costs. 4. It is harmful to the environment. Sure tailpipe emissions are down, but you have to look at the entire process. The long and short of it is that the additional pollution caused by creating it is greater than the reduction in tailpipe emissions caused by using it. Among many other studies, there is one by the WI DNR showing this.
      harlanx6
      • 7 Months Ago
      Ethanol in fuel reduces imported oil, so that's good. Using corn to produce it takes food crop land away from food production and the net effect of that is bad. Alcohols don't store as much energy as hydrocarbons of similar weight. If home produced fuels, like ethanol can be used for fuel in place of middle eastern oil, I'm all for it. It's just that important. Let's do it for the right reasons, not because of government subsidies. I don't think corn ethanol is the right solution, but others are coming. As far as the E15 debate, it's pretty transparent. The oil companies are against it and the farmers are for it. A little self serving do you suppose? The oil companies have resources to out bid everyone else for the services of our Senators and congressmen (who are for sale, but they are not cheap), so that looks grim for the farmers. The question is what is best for the nation, not who is going to have the most money to get reelected.
      • 7 Months Ago
      Prior to the Clean Air Act, gasoline contained tetra-ethyl lead, a gasoline additive that increase octane, reduce knocks, and lubricate valves. After seventy years of lead poisoning from gasoline combustion spewing into the environment and harming children, the federal government finally had the courage to tell Big Oil to stop. Big Oil insisted MBTE, methy-buty-tetra ether, as substitute rather than ethanol because Big Oil's refineries make all of it. Despite MBTE as a known carcinogenic compound, government officials ,having fornicated with Big Oil for decades, permitted the chemical as the de facto gasoline additives.

      To demonstrate compliance with water standards as called out in the Clean Water Act and California CEQA, all municipal water companies must publish and report of water quality. The trouble with MBTE began when several water companies reported significant levels of MBTE above safety limits. Soon, almost the entire southern California ground water was found to be contaminated with high level of MBTE. The sources were the hundreds of old leaky under ground gasoline tanks aggrevated by MBTE solvent action. As there is no way to separate MBTE from drinking water, many water companies had to buy water to pipe directly to users or for dilution until a solution is found.

      Big Oil fought long and hard insisting on the value and safety of MBTE despite the obvious catatrophic health implications. Ethanol finally became the additive of choice because it is bio degradable in the soil, produced domestically, strong agricultural lobby, and its combustion does not produce heavy metal poisioning.
      • 7 Months Ago
      The amount of ethanol required to produce RFG is only 5.79%. Above that level, there is no benefit in emissions. And if you are not in an area that requires RFG, the presence of ethanol is not due to that.

      E10 and any other mixes over 5.79% are produced in order to meet federal blending mandates. These are currently 13 Billion gallons a year, 40% of the corn crop, which requires more than the RFG percentage of our gasoline to be ethanol.
      • 7 Months Ago
      Congrats: 41 years since the first Earthday.
      and ethanol has been subsidized almost as long.
      That's right. Ethanol has been subsidized since the 70's and it still cannot be produced or sold at a profit.

      40% of our corn crop. Makes our food costlier - no doubt (for those with any common sense)

      Takes two gallons equivalent of diesel and/or other fuels (like natural gas) to produce 3 gallons of ethanol - plus lots of water.
      And, then your car gets worse gas mileage.
      And, then overall more pollutants and more CO2 are produced.


      Most excellent results - from a most excellent DOE program.
      DOE started in 1977 - tasked with "reducing our dependence on foreign oil"
      and this is all they've been able to come up with so far.

      Another perspective: If ethanol didn't suck all the lion's share of the alt. fuels, maybe something else would be viable by now.

      The government has never been good at picking winners and losers.
      (take Fisker for instance). More and more - STUPID STUPID STUPID
      and uncle sambo can't think of anywhere to cut
        • 7 Months Ago
        "So, now that we know why most gasoline has some ethanol in it. The next logical question is: do you need to worry? The answer is a qualified no. Modern cars and trucks can capably burn E10 (a blend of 10 percent ethanol and 90 percent gasoline) and some automobiles should not have any problems running E15, a gasoline blend that will likely start to appear at fueling depots across the nation this summer. " This really depends on your definition of "Modern cars". There are still many cars from the '80s on the road, and the majority of them are NOT compatible with this garbage. I say garbage as both a degreed Mechanical Engineer, and as someonw who knows quite a bit about how cars function. I personally have a 1987 BMW 3-series that still runs fine and gets decent mileage. However, it says right in the owners manual not to use gasoline that contains ANY alcohol. This is becase of the damage it does to the rubber seals throughout the fuel system. Isn't one of the ideas of "being green" recycling and cutting down on waste? How about the waste involved with buying a new car when the one you have woks fine and does what you need it to do? Sure, much of the old car can be recycled, but have you ever considered how much energy it takes to do so? That energy, plus the energy required to make the new car that most people don't really need anyway adds up to a fairly large amount. Sure, it's fashionable in green circles to own the newest, most efficient hybrid available. However, have you really thought about wether it's actually the best choice? Reformulated gas is basically the same way. There is a mountain of evidence proving that it is NOT effective at reducing our dependence on foreign oil, and it is also not effective at reducing pollution. Sure, if you only look at what comes out of the tailpipe of your car it is a little cleaner (just a little). If you look at the complete process, however, it has been proven to create more pollution than the regular gasoline it replaced, and at a higher energy and monetary cost as well. Additionally, the alcohol makes the reformulated gasoline more caustic than unreformulated gasoline, so all the parts in the engine will wear out more quickly, including the metal parts. Among other things, this means the car will start running less efficiently and creating more pollution earlier. The whole thing is a big sad joke on the American People. I am all for reducing pollution, but as an Engineer I am interested in results, not smoke and mirrors. Reformulated gasoline is very definately smoke and mirrors, and we are all paying for it.
        • 7 Months Ago
        You two are completely wrong, It's closer to 1 gallon of Diesel to make 20+ Gallons of Ethanol.

        Most of the energy in Ethanol is from Coal or Natural Gas. Which are much more desirable than Foreign Oil. And gallon equivalent is used for MPG not for manufacturing...
        • 7 Months Ago
        My admittedly rough analysis:

        take 1 gallon of diesel fuel - farming and transportation uses
        +
        take 1 gallon energy equivalent natural gas - distillery energy use - process heat and electric power (pumps, lighting, etc.), make fertilizer, herbicides, etc.
        +
        a lot of water - and polluted water run-off
        +
        about one dollar in federal subsidies
        =
        3 gallons of ethanol

        Add it to my gasoline:
        and I get less gas mileage
        and more evaporative losses
        3 gals of ethanol has the pollution and CO2 of 5 gals of fuel (see above equation)
        and pay more for ethanol (and subsidies add to the national deficit)
        and I pay more for food

        Who thought of this insanity ?

        DOE
        Started in 1977 (by Carter) to "lessen our dependence on foreign oil"
        Now 16,000 permanent employees, and 100,000 contractors
        An annual budget of $26.6 Billion (FY2010)
        And 34 years later we're using more foreign oil than ever,
        and ethanol is the best plan they've come up with. LOL


        • 7 Months Ago
        Yes, 'cause God knows what the US needs is cheaper corn. Then we could use it to make the other 2% of our food that not already made out of corn.

          • 7 Months Ago
          Typical mindless and factless response. A few of the relevant facts are that farmers are planting corn instead of other food crops just because of the ethanol subsidies they can get. That creates a shortage of other vegetables and as a result drives up the price of those vegetables. It's called supply and demand. Also, with as much corn being used for ethanol to create reformulated gas as we are currently using, it actually does also cut down on the amount of corn that is available for food-related products. That also creates a shortage of corn and we are back to the supply and demand issue. Opinions, no matter how much you like them, are no match for facts.
        • 7 Months Ago
        "40% of our corn crop. Makes our food costlier - no doubt (for those with any common sense)"

        That 40 percent of the corn crop also makes other products such as corn oil, animal feed, etc. Only the starch in the corn is fermented into alcohol.
      • 7 Months Ago
      You should see what a clusterf*ck the introduction of E10 in Germany is.

      The amount of FUD, disinformation and bullshit from both the oil industry and environmental groups is mind-blowing, while the government helplessly flails around in a futile attempt to contain the failure and the media, as always, are eagerly pouring fuel into the fire.
      • 7 Months Ago
      Haha, yup..

      I haven't been posting here very often these days but i'm glad to see someone else carrying the torch ;)

      The fluff is definitely annoying here. There is a lot of interesting news elsewhere that could take it's place..
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