Updated on 05.22.07

Ethanol Blends: Are They Worth It In Your Tank?

Trent Hamm

In Iowa, E10 gasoline (fuel composed of 10% ethanol and 90% gasoline and safe to use in normal engines) is typically $0.10 per gallon cheaper than 100% gasoline. However, the E10 fuel is less efficient than pure gasoline, enough so that it is noticeable over a long sustained trip – we typically drive three hours in a row to visit family and the difference in gas left in the tank is noticeable at the end of the trip.

I did some research and discovered that E10 fuel is about 3% less efficient than non-E10 fuel. So, for example, let’s say my truck gets exactly 17 miles per gallon with regular fuel. This would mean that it gets 16.49 miles per gallon with E10 fuel.

As I mentioned earlier, E10 fuel is typically $0.10 per gallon cheaper than 100% gasoline here in Iowa, so is it cheaper to use E10 fuel or regular fuel in my truck? Current gas prices are $3.29 per gallon for E10 fuel and $3.39 per gallon for regular fuel, so we divide each of those by the respective miles per gallon I get to find out that the difference between the two is microscopic: $0.1994 per mile for “normal” gasoline and $0.1995 per mile for E10. Thus, the price difference is completely negligible and you have to consider other factors when determining which to use (environment, octane, etc.).

What can we learn from this, especially if we look outside of Iowa’s borders?

First, there is a real difference between 10% ethanol blend fuel and non-blended fuel. The non-blended fuel is simply more efficient than the ethanol-blended fuel, as I’ve noted both by research and by observation. If you can get both E10 and regular fuel at the same price, the regular fuel is the better choice.

Second, the difference in gas prices in most areas even outside Iowa brings them close together in terms of cost per gallon. This is mostly because ethanol costs about $1.20 a gallon to produce, and thus a E10 mixture reduces the price of the gas by just a few percent – almost equivalent to the lack of fuel efficiency.

Third, the environmental issue, at least in this comparison, is negligible. The E10 is better per gallon for the environment, but you get fewer miles out of that gallon, so in the end, the benefit becomes very tiny. Don’t let environmental issues sway you, at least not until E85 comes into wide adoption and engines designed to use E85 (or pure ethanol) are in use. When that happens, then the ethanol will be as efficient as gasoline and much more friendly to the environment.

To summarize, if you have a normal car, the environmental and cost benefits of 10% ethanol blend gas are negligible, and if you can get normal gas at the same price, go for the normal gas. However, when E85 or pure ethanol engines break into the mainstream, they’ll have engines that are designed to run optimally on ethanol, at which point you’ll be much better off using those in terms of both cost and environment.

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  1. Eric says:

    Use of ethanol also has some severe impacts on your bottom line ( besides the cost per mile ).

    Corn is subsidized in the US so ethanol is artificially cheaper at the expense of higher taxes.

    Because ethanol is “big” right now it’s actually having a material impact on cattle and poultry farming since cord is the main staple in the feed.

    and with ethanol subsidies coming down from congress it might get even worse before it gets better.

  2. Matt says:

    I wouldn’t say the environmental issue is negligible, more like debatable. However, the economic impact is not debatable. The use of ethanol is raising prices for staple foods worldwide and having an impact on millions who already struggle to put food on the table. In Feb. rising corn prices caused tortilla prices to double in Mexico leading to riots in Mexico City.

    Politicians in the US have sold ethanol as some miracle cure for all our environmental and energy problems in an effort to garner easy votes from environmentally conscious Americans. The reality of the situation is not nearly as idealistic as they would have you think. There are very real consequences to filling your tank with E10.

  3. Chris H says:

    I would like to point out something about ethanol that’s often obscured in media reports: not all ethanol comes from the same place. The ethanol that’s being discussed here is starch ethanol, which in the US comes primarily from corn (wheat is more popular in Europe). Obviously corn ethanol directly competes with human and animal food streams, and there is no question that this is already causing problems. In Brazil, a major ethanol-using nation, it is fermented directly from sugar extracted from sugar cane.

    Another viable source of ethanol is cellulose, a structural carbohydrate that makes up the stems and stalks of plants. You can’t feed this material to humans or animals, and this ‘agricultural residue’ is quite often simply burned or landfilled. The cellulose can be broken down into glucose, which can be fermented into ethanol, using enzymes produced by fungi or bacteria. This technology is more expensive than using starch to make ethanol, but it is already competitive at today’s oil prices. The media is starting to do a better job in conveying that there are different ways to make ethanol, with varying degrees of environmental impact depending on source, but there is still a tendency to refer to a single, homogenous ‘ethanol’.

    Full disclosure: I am a scientist currently involved in studying the enzymes that break down cellulose. I should also note that I don’t necessarily believe that ethanol is the be-all, end-all fuel solution, but I do believe that it can serve as a valuable bridge technology while other fuels/technologies are developed.

  4. S. B. says:

    Is the efficiency issue really related to the engine very much? I thought the basic problem was that there is simply less energy stored in a gallon of ethanol than a gallon of gasoline. Thus, if an engine processed both fuels with an efficiency of 30%, for example, the car still wouldn’t go as far on a gallon of ethanol as it would on a gallon of gas.

    This is not my area of expertise, so someone please jump in and correct me if this is not accurate. Thanks.

  5. HardwareGuy says:

    A gallon of ethanol has less stored energy than a gallon of gasoline, so even when engines come around that are optimized for 100% ethanol they will still get less MPG than a comparable gasoline engine.

    BTU per gallon
    Gasoline – 114,100
    E100 – 76,100


  6. UncleOxidant says:

    The rush to corn-based ethanol is a disaster: It’s a money losing proposition except for government subsidies. It’s a net energy loser: takes more energy to create than it yeilds. It’s an environmental disaster: more chemical fertilizers, pesticides, and herbicides used, more land under cultivation, more water diverted from underground aquifers. It’s causing food prices to rise globally. It would not be a viable business were it not for huge government subsidies.

    There are much better ways of producing bio-fuels. The most promising is to grow algaes on sewage waste. With corn you only get one crop/year, but with algae you get a crop every month and fertilizer too.

    Cellulosic ethanol is still a science experiement at this point: if we can get it working it would improve the yield of corn-based ethanol, though it would be better to use things like switch grass that don’t need much in the way of cultivation, pesticides or herbicides.

  7. Trent Hamm Trent says:

    Obviously, there are significant political issues afoot with ethanol. Trust me, I live in Iowa and I see it all the time. The thing is, though, it’s not really helping the consumers at all to this point.

  8. Thanks for the write-up, Just today I was discussing this subject with a colleague.

  9. EdTheRed says:

    ‘scuse please. I’m driving an ’03 Corolla. On the highway the thing cannot seem to get under 40 MPG, or much over :-(

    So, based on the above, my next personal transportation will be powered by a system that can a) sip very sparingly from the petro/bio/whatever fuel tank b) run on electricity as well as internal combustion and c) generate it’s own electricity from braking/solar/whatever. And most probably built by Toyota.

    BTW, it’s gotta be able to move four adults, four carry-ons and two large suitcases. My Corolla does this.

    In terms of future purchase, the Toyota’s Synergy drive meets most of the above. I’m sticking with Toyota because of the quality: The above mentioned Corolla has 44,000 miles and has had oil and filter changes and one set of tire. Nothing else. The thing runs like the day I drove it of the lot.

    I will buy a Toyota Synergy Drive sometime in the next three to five years because I am impressed with the quality of my current Corolla (so I believe that Toyota extends that quality to the Synergy Drive), and because it’s soooo much easier to go hybrid than to do flips and twists for sci-fi Hydrogen Fuel Cells (woosh, look it’s W flying around in a jetpack!), bio-dielsels (honey, are we driving around behind a fast food restaurant?), etc.

    Just my .02 cents. I may be completely wrong, I often am.

  10. Leslie M-B says:

    I’d be more enthusiastic about ethanol if its production and transportation didn’t require the use of so many fossil fuels. I’d also be happier if it didn’t encourage monocultures laced with pesticides. Ewwww!

    I went to college in Iowa, and I was shocked to learn, in the middle of the greenest summer landscape I’d ever seen, that so little of the state is actually natural. It’s mostly soy, corn, alfalfa–monocultures. Is that really the kind of landscape we want to promote elsewhere?

    Yes, fossil fuels need to be replaced, but I’m not convinced ethanol is the answer.

  11. Stanley says:

    I came across your blog in DebtCC Blog Hunt.I like this blog and became fan of it.I never thought of the E10 gasoline but now it seems I was a fool to not doing it.Another aspect of choosing it is the environment issue.So big thanks to you one more time for this info.

  12. Have there been any studies on the effects of the two types of gasoline on engines and components? I wonder if one would produce more wear and tear in the long run.

  13. kevin says:

    I agree that ethanol is probably not the answer. Are government subsidies ever is the best answer? I don’t think so.

    John Stossel just wrote a great piece on this today too.

  14. Rob in Madrid says:

    If Americans were really serious about reducing gasoline consumption they’d switch over to deseil. Over 50% of cars in Europe have desiels under the hood. Benifets more power and about 30% more mpg. I’ve been driving a desiel for about 2 years and I’d never go back to a gas engine. Usually desiel is cheaper.

    Secondly American cars are way over powered why in gods name do you need 250hp to take the kids to school. I lived in Germany for 7 years and 80% of the cars are under 100hp yet when summer comes you see the autobahn jammed with the small cars (think Honda Accords) pulling 20 foot trailers and most of those cars are in the 120 hp range. Even large German SUVs come in lower HP than the equilavant American SUV.

    Secondly lower HP doesn’t mean sticking to the right lane. I had ran an Audi A4 for 3 years and even at a whimpy (by American standards) 130 HP I had no problem crusing at 110 (180 kph) all day.

    Incedently 70% of the German autobahns have speed limits (not that I paid much attention trick is to know where the cameras sit) and heavy traffic means you can’t run flat out much anymore.

    My wife was in Germany recently with here boss and he hit 160 MPH on the autobahn before she finally told him to slow down! He went down to a more sedate 90 mph (180kph)

  15. cami says:

    I’ve actually been wondering about this myself lately. I don’t think that the environmental impacts are negligible, but I also haven’t come up with a good way of quantifying these. We have a good idea of how bad gas is, but not as much concrete evidence as to how detrimental ethanol can be. There are estimates that it takes 4 gallons of water to produce 1 gallon of ethanol. While some steps can use grey water, some cannot. Plus continuous crop rotations can have be bad for soil and reduce production over the longer term. Then they are the political realities and huge price volatility of both gasoline and ethanol productions.

    I don’t know how far away cellulosic based ethanol is. I’m currently at a university that is (probably) one of the top three for biodiesel research, and I hear a lot about it, but it still seems like a ways off.

  16. Bil says:

    Corn-based ethanol is acceptable as an oxygenator, but is unsustainable for fuel use.

    I am extremely skeptical of claims about cellulosic ethanol.

    I’ve seen many press releases, but little data on how much ethanol has been produced.

    It does appear that it is still confined to the lab bench (you can get amazing results in the lab which do NOT translate to commercial scale production)

    The only verified program I know of was the TVA’s pilot scale plant that used wood chips. But they had to use sulfuric acid to break down the wood chips, and that proved too expensive.

    Rob’s right that diesel is the way to go at this point in time if you must drive and want to minimize the environmental impact.

    Efficient turbo-diesel cars like the Jetta and Passat get better mileage than any gasoline burning hybrid, in the city or on the highway.

  17. Lisa says:

    Like HardwareGuy said, it is not engine technology that makes the difference in fuel efficiency between ethanol and more traditional gasoline. It is still combustion that is required and the chemical bonds in ethanol will result in less energy (joules, BTUs, mpg, or however you choose to measure it) per gallon.

    Making fuel from food just doesn’t seem smart.

    Ethanol is, convienently, easily biodegradable when it spills. However, when mixed with gasoline it makes a spill more of a problem as it makes the nasty components of gasoline (eg: BTEX components) more soluble so groundwater plumes will be larger. This may not seem like a big deal, but ethanol can corrode underground storage tanks faster unless they are a special type (not at all common) made especially for the increased ethanol content.

  18. moiety says:

    I occasionally put E85 (fairly easily available in Austin) in my flex-fuel-ready truck, and the impact on mileage is -considerably- greater, even in an engine supposedly designed to work with the stuff.

    I probably get a MPG drop of 20%. It sure doesn’t cost 20% less.

    Admittedly, acceleration seems just a teence faster, but not enough to be worth the mileage loss.

  19. Jennifer says:

    John Stossel, whistle-blower of 20/20 fame, had an interesting column on this topic recently, called the Many Myths of Ethanol:

    Some highlights:
    “Studies show that the amount of energy ethanol produces and the amount needed to make it are roughly the same.”
    “Because ethanol degrades, it can’t be moved in pipelines the way that gasoline is. So many more big, polluting trucks will be needed to haul it.”
    “For corn ethanol to completely displace gasoline consumption in this country, we would need to appropriate all cropland in the United States, turn it completely over to corn-ethanol production, and then find 20 percent more land on top of that for cultivation.”
    “Studies indicate that the standard mixture of 90 percent ethanol and 10 percent gasoline pollutes worse than gasoline.”
    “Virtually all studies show that the greenhouse gases associated with ethanol are about the same as those associated with conventional gasoline once we examine the entire life cycle of the two fuels.”

  20. Oscar says:

    I hope people actually realize one important point in using 10% ethanol: Less money going to the oil rich countries that practically controls our countrys economic future. 10% in a single state may seem so small, but at least we are sending a message. Too bad the leadership of our country does not have the strength to have “Manhattan Project” type of a change, so we may be free from Ahmadinejad, Chavez, Gaddafi and the likes.

    I can always see why a person would defend or go against other arguments for ethanol. But I cannot see anything negative from setting us free from the clutches of our oil addiction.

  21. Trent, do the calculation with your Prius. The result may surprise you!. Where I live in New Mexico we have E10, no choice and my Prius has gone from 44 to 42 MPG in winter driving. I will see what it does over the summer. Inherently, ethanol is not as efficient a fuel as gasoline and our current ethanol substrates and production methods are not efficient as well. If those things do not change, I suspect people will see an increase in fuel costs as we move to blends higher in ethanol.

  22. Andreas says:

    Thank you for a clear exposition of facts – issues such as these are fraught with self-interest and ignorance!

    A very short debunking book on economics – Economics in one lesson by Henry Hazlitt – may also be of interest to your readers.

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