Fuel Testing Reveals Higher Octane in Ethanol

Last July, the government announced plans to raise corporate average fuel economy (CAFE) standards to 54.5 MPG by 2025. The automotive industry responded saying the MPG number was an attainable goal by utilizing high-efficiency internal combustion engines that deliver lower CO2 emissions. However, one hurdle to address is that these high-efficiency engines need higher-octane fuel to realize their full fuel efficiency and performance potential.

Making higher octane gasoline at the refinery is an expensive process that is passed on to the consumer. So, can a cheaper and more environmentally-friendly source of octane be found in ethanol?
Yes, according to the fuel testing results just released. The fuel research was conducted by AVL, a global industry leader for the development of powertrain systems with internal combustion engines, instrumentation and test systems. The fuel testing study was funded in part by ICM. The first phase of fuel testing began in January 2011 and ended in December 2011.

Identifying A New Way to Test Fuel

Recognizing ethanol’s full octane value required some practical thinking about how ethanol is added to fuel, and to show how ethanol performs in new direct-injection engines. The AVL tests incorporated multiple gasoline base fuels, various compression ratios and several automotive fuel systems to demonstrate ethanol’s performance.

One of the surprising results revealed in this testing was the additional benefits of ethanol’s favorable octane sensitivity. By plotting both ethanol’s chemical octane and sensitivity benefits along with the cooling effect, test results showed that ethanol offers twice the octane potential. The focus of testing was to evaluate the various fuel blends along a range of knock limit operation rather than just evaluating one set point as is done today.

“Until now, most testing of ethanol allowed match blending and the base gasoline varied each time ethanol was added – which yielded inconsistent results due to variability of the gasoline fuel. As an effect of this particular testing approach, it limits the ability for results to show increased performance of ethanol. This new testing data has proven to be a great tool to illustrate how much performance can be achieved by simply adding ethanol to gasoline. We are seeing a significantly higher value for ethanol and use of intermediate blends to support the changing needs of the automakers and the new fuel efficiency standards that have been issued,” said ICM’s Steve Vander Griend.

Yielding Higher Octane Performance

The fuel performance study revealed that E30 yielded higher octane performance compared to Iso-Octane, which is the reference fuel for determining the 100 octane scale. Current testing standards of the American Society for Testing and Materials (ASTM) would show much less octane potential for E30.

“These real-world results show that ethanol blends have the potential to offer much more octane value than previously estimated by methods prescribed by the ASTM. This is very good news for automotive engineers who are looking to higher-octane fuel as they strive to meet higher fuel efficiency and performance standards. Most importantly, consumers stand to gain the most from saving money at the pump,” continued Vander Griend.

Ethanol’s favorable performance can be particularly beneficial under high engine load conditions that often result in contributing to higher emissions from motor vehicle exhaust. The potential benefits include lower emissions and better fuel economy which equates to lower C02 per mile with utilizing mid-level ethanol blends.

ICM looks forward to supporting future fuel test studies that will continue to prove the performance and value that ethanol delivers. In addition, through continued collaboration with various stakeholders, the biofuels industry stands ready to assist in achieving aggressive fuel efficiency standards that will reduce our dependence on foreign oil and promote cleaner cars that won’t pollute our air or constrain consumers’ wallets at the fuel pump.

19 thoughts on “Fuel Testing Reveals Higher Octane in Ethanol

  1. If it’s such great stuff, then why do my miles per gallon take a 10% hit every time I fill up with it? Ethanol is junk, the science behind it is junk. It’s been promoted by using one lie after another. The saddest part is what it does to the price of food, which may not be a problem in the US, but when you work all day for $2.00 or less, like 40% of the people in Egypt for example, then when the price of all grains is driven higher by corn ethanol, suddenly you can’t afford three meals a day, now it’s just two. Think about that the next time you get a little bit hungry. Americans can’t picture the suffering corn ethanol has created because it’s something we’ve never experienced here, but it’s very real to the poor. So all you corn farmers out there? You’re balancing your check books on the backs of the poorest of the world’s poor. Think about that the next time you roll the new Corvette out of the garage.

  2. Stop using GMO corn fuel ethanol in my gas.

    Gmo ethanol stinks.

    Is California using Brazil ethanol for BP and Shell credits

  3. First of all Mr. Peterson
    If you are noticing a 10 percent mileage loss with E10 in your tank, you need to change gas stations because it is not the ethanol causing your mileage loss, it is the gasoline. What you don’t know is that the oil companies can make a cheaper gasoline as long as ethanol is added.
    May be you should look for facts rather then submit your opinion.

  4. Low mileage on E10 is caused by 90% low octane(83) gasoline not the 10% 114 octane ethanol. This gasoline they mix in is so crappy it can’t be sold UNLESS ethanols mixed in. Thats why higher blends of ethanol (20-30%) get better mileage cause theres less subgrade gasoline in it. Try blending regular 89 octane gas with ethanol and youll see what I mean. Mileage is pretty much unchanged or better.

    oil extraction patented by GreenShift
    VaLerO said theyd get around Gers patents with a different pending one from Icm see here http://www.stormlakepilottribune.com/story/1765748.html
    but the Icm pending patent failed was rejected late november go to here http://portal.uspto.gov/external/portal/pair
    type this in 13/105789 this number is rejected patent VaLerO “licensed” from Icm
    If VaLerO wants patented oil extraction they must license Gers or lose in court for infringement

    VaLerOs patent failed Gers will sue if needed
    POET tried same trick ie to patent oil seperation that Gers already patented http://biodieselmagazine.com/articles/8218/poet-corn-oil-enough-for-12-mmgy-of-biodiesel-by-years-end
    but like Icm, POETs oil patents rejected
    Enter Poets application number in same patent website above 12/208127 all POETs rejected late november
    Gers has only valid patents
    all big name clientsof Gers

  5. Peterson. If u were really worried about people overseas being able to afford a meal. You would never set foot in another walmart again.

  6. Ethanol is junk. Gasoline has no oxygen its a hydrocarbon. Ethanol has oxygen because it is an alcohol. It’s basically partially brunt fuel which means it has way less energy potential. It is a crime against humanity to tunr corn into fuel instead of feeding the masses. Another example of how liberals focus in so narrowly on one aspect they miss the whole picture.

  7. My thoughts regarding some of the comments that were left…

    1) Octane is not a measure of the energy in a fuel, it is an indication of the tendency of a fuel to resist autoignition (i.e. “engine knock”).
    2) All else being equal, your vehicle may get slightly less gas mileage with ethanol, because ethanol simply doesn’t have the energy-per-gallon that gasoline does.
    3) The oxygen contained within ethanol helps to promote thorough combustion of gasoline when burned in an engine. It’s called an “oxygenate”. Ethanol has replaced MTBE as the oxygenate of choice for fuels, because MTBE was found to have significant environmental impacts.
    4) GMO crops help to maximize yield. A field of GMO corn can produce far more starch per acre to turn into ethanol than ‘normal’ corn would. So, land use is minimized, and energy and water used to produce the crop are minimized. These are good things.
    5) Burning oil returns carbon that has for aeons been trapped under the earth, and releases it into the atmosphere as CO2, which is a greenhouse gas. Ethanol, produced from renewable sources (corn is but one source – consider also sugar cane and cellulosic feed stocks) gets its carbon from CO2 in the air… The CO2 is taken in by the plant and converted to biomass driven by energy from the sun, and the ethanol process converts that biomass to ethanol, and when the ethanol is burned, the CO2 goes back to atmoshpere to complete the cycle – consider it an indirect form of solar energy. Granted, the ethanol process consumes water and energy (so does the oil refining process), but the carbon cycle related to the fuel itself is a closed loop.

  8. This is an excellent article. Antidotal stories about increased efficiency and performance using E30 have been around for years. This story puts some facts behind those stories, and how testing methods for ethanol blends may need to be different than those for straight gasoline. To obtain high milage standards, higher thermal efficiencies in IC engines must be obtained. Engine engineering based on gasoline can take you only so far. Real efficiency improvements must be found in the fuel. The increased thermal efficiencies available in ethanol fuels more than counter balances its lower energy density.

    It is unfortunate that fact based articles like this are met with prattle from uninformed opponents using the universal catch phrase “ethanol is junk” and making a food for fuel argument that cannot be justified. The ethanol molecule is specific and can come from many sources. To discuss the value of corn and the ‘corn ethanol’ industry to the economy, oil prices, food prices, improved livestock feed, etc. would require a whole article.

    To ‘concerned chemist’ – most gasoline sold in the US is required to be oxygenated to reduce smog. If you really are a chemist, you should know that other options for oxygenation actually result in lower energy densities that E10.

  9. Interesting article with EtOH bias. What happens to the driveability index (DI) and RVP of the E30 fuel? Given the nature of an alcohol and in particular EtOH’s boiling point/curve, the blended E30 will have poorer DI, blended fuels 50% boiling point, compared to 100% hydrocarbon fuel. Also, as EtOH is added to the fuel, the RVP goes up and more of the fuel will “weather off” at ambient conditions. Due to the RVP increase, the base gasoline RVP may need to be reduced. Reducing the base gasoline further negatively impacts DI. Octane, DI and RVP are just three of many ASTM fuel specification requirements for “gasoline” motor fuel.


  10. From a fuels and engine industry perspective I do not think there is one thing new is the ICM study – it is just a bunch of marketing fluff. The high octane value of ethanol has been known since the 1930’s – we are talking 80 YEARS AGO. The octane blend sensitivity is also known, and the in-cylinder cooling effect, especialy in GDI engines is ALL KNOWN for decades. I guess a younger generation has to re-learn it. Maybe they ought to crack open a book (but wait – nobody reads anymore)

    Responding to some of the posts in the comments section;

    Sorry but low mileage is not due to the gasoline…

    The energy content of gasoline does not depend on its octane number. Octane number is a measure of the fuel’s tendency to knock – which is pre-ignition due to compression before the spark goes off. Octane is a function of the molecular structure of the individual types of molecules that make up gasoline blends (hundreds of different kinds). Energy content is primarily a function of the number of carbons, hydrogens, and oxygens in each molecule. In other words iso-octane (a molecule with 8 carbons and 18 hydrogens) has high octane, whereas normal-octane (also 8 carbons, 18 H’s) has low octane but the same energy content. The reason why these two octanes differ greatly in octane has to do with how the 8 carbons are assembled either as a branched chain, or as one single chain of atoms.

    Using US Government figures (EIA), the energy content of ethanol is 83,333 BTU/gal, and gasoline is 125,000 BTU/gal. The energy content of the mix is the linear combination of the two – so E10 gasoline (90 vol% gasoline + 10 vol% ethanol) sold today at the pump is 0.9 x 125,000 + 0.1 x 83,333 = 120,915 BTU/gal which is about 3% less energy content. E85 is about 25% less energy than gasoline. So the more ethanol you add, the lower your mileage because there is less energy available.

    Gasoline sold at the pump needs to meet the specified octane number shown on the pump (e.g. regular is 87 R+M/2). The reason oil companies blend “crappy” gasoline with ethanol is because the final blend, let’s say it is 10% ethanol and 90% gasoline, the final blend has to meet the octane spec. Ethanol has an octane value of around 113. Again it is the linear combination method to create the blend. Let’s say you want to make 87 octane with 10% ethanol, then the equation to solve is 87 = 0.9 x GON + 0.1 x 113, solving for GON (the gasoline octane number), you get 84 as the octane for the base gasoline. So yes, you cannot sell this 84 octane gasoline, you have to blend it with something having higher octane so that you meet the final spec. The oil company is not going to blend 87 octane gasoline with 113 ethanol at 10% – if they did the resulting octane would be around 90. They are not going to sell 90 octane product for the price of 87. Your engine and millions of other consumers needs 87 and you do not want to pay a premium for 90 octane if you do not need it right? If you were running the refinery what would you do genius?

  11. Another comment about the need for oxygen in gasoline to reduce smog – that is now BUNK.

    Oxygenated fuels made some sense back in the 80’s when you were in diapers and your mom and dad were rocking out to Duran Duran.

    In the 80’s oxygenated fuels help reduce some harmful tailpipe emissions but the main one they reduced was carbon monoxide. Those cars had open-loop control systems and emission control was not so good.

    Cars today use close-loop control systems with three-way catalytic converters. The control loop uses oxygen sensors to control the air:fuel ratio so that the catalyst can do its job. When oxygen is added to the fuel, the control systems “sees it” and makes compensating moves. There is no longer a major benefit to having oxygen in the fuel.

    The ethanol industry likes to promote this outdated myth.

  12. Tim G, you better do a little more research on your RVP info. Pure ethanol has a very low RVP. After about E20 blend RVP goes DOWN compared to the base gasoline.

  13. We should consider methanol instead of ethanol as it removes many of the drawbacks mentioned by other commenters. It can be made from coal or coke and natural gas or it can be made from natural gas and carbon dioxide. It can be used anywhere gasoline is used. Ideal useage is in large vehicles such as railroad, trucks, ships; since a larger volume would be required, it could not replace jet fuel. It could replace heavy oil and or LPG in some heating applications.

    It is much cheaper than gasoline or ethanol, even on a heating value basis.

  14. Tim-G, I know a fair amount about the DI index based on T10, T50 & T90. I plotted every one of the fuels used in this testing and many of the fuels listed in SAE papers along with the EPA studies. Since ethanol cuts right below T50 and offer the highest octane blending component available, the benefits go towards ethanol. The DI was only created due to the wide variation of hydrocarbons in gasoline. Have you ever looked at the DI for E85, other than poor T10 and the associated cold start, tell me how E85 can perform so well with a non-existent curve?

    I have to wonder why the ethanol correction factor is at the end of the DI equation. Is it so the oil industry can make a cheaper and possible a gasoline prone to more emissions? You should buy SAE’s paper 2010-01-2115 & 2010-01-2117 and then ask yourself what you are putting in your tank.

    E30 will be roughly .5 psi lower then E10 and by E40 to E50 depending on the mole fraction of gasoline, the vapor pressure is back equal to E0. Typically, higher than E50, a pentane or butane has to be added in order to increase for the rvp requirements.

  15. Mr. Refinery- You say this has been known for years? I don’t know of any study in which the range of knock has been tested. Yes, octane sensitivity at MBT (Maximum Brake Torque) has been shown but what happens when the engine reaches the knock limit of the fuel. Ethanol significantly reduces the amount of retarding needed in order to avoid knock at high load.
    I don’t see many who use high heating values so if you want to dig into technical papers, you should start using the lower heating values for both ethanol and gasoline. Ethanol with 2 percent denaturant is roughly 76600 BTU’s. Most test fuels average 114,500 BTU’s (roughly) but this can dip down to less than 113,000 in the market place. Your percentages are nearly correct in that ethanol if splash blended to E0 should lower the BTU value of E10 by 3.2 percent.
    What you are not recognizing is that peak efficiency for gasoline engine is roughly 32-34 percent on consumer gasoline and you are likely to see less than 25 percent over your normal drive cycle. If you can raise this number to just over 27 percent, now you just close the mileage gap with E30.
    Even in this study, higher octane E0’s had more efficiency available since efficiency goes up with load. This is why OEM’s are considering options like downsizing of the engines. Just look at the Ford F150 with a 3.5 liter engine. The limiting factor for this engine will always be the knock limit of the fuel. When you retard timing, you will lose mileage. You should see the value when you get all the cooling effect with direction fuel injection and take full advantage of ethanol’s octane and sensitivity.
    I don’t think I will comment too much to the methanol post but methanol has half the BTU value compared to gasoline and a significant corrosion and health concern.

  16. I agree with some of these guys, the supporters have great green ideas but have no idea how an engine works and need to shut up.

    The reason your engine gets worse mileage on ANY ethanol blend of x octane vs. normal gasoline mixtures of the same x octane rating is this:

    To run efficiently a fuel to air mixture should be around 14:1, roughly. So your ecu sprays one cc of fuel in each cylinder for each 14cc of air it senses going in, per say.
    Gasoline is a complete fuel. Ethanol is as mentioned above an oxygenate. Each cc of fuel sprayed is actually just adding LESS burnable fuel than a cc, and some more oxygen. Therefore, the engine then senses lean burn (more air/less fuel than required) and sprays MORE fuel to make up the difference. Either your ECU is stupid and continues running lean and knocks, OR your ECU is smart and sprays more to help richen the mixture up to normal levels.

    This is why your mileage sucks.

    Add to that your non flex fuel designed fuel system corrosion, fuel filters stopping up, o rings and injectors drying out and leaking or locking up, and a million other issues, and you have a cluster**** of problems. I went to college majoring in engine design and machining. I work at O’Reillys. I thank the government because the amount of fuel pumps on fairly new cars and a LOT of older ones we have been selling has really boosted my commission.

    You could probably save the food shortage by only drinking Clorox. That doesnt make it good for you.

    Same goes for your car.

    K thanks.

  17. What you are all missing is that your cars currently have low compression ratio. The real benefit of using 114 octane Ethanol is that you could use a smaller engine having smaller pistons and still create the same torque…but only if it doesn’t knock. That is the true benefit of ethanol: smaller engines creating the same torque at higher compression ratios. Think about it, why do propeller airplanes use av-gas (octane about 140)? The reason is so they can have smaller lighter engines that go farther on a gallon of gas. Try this one: why do drag racers use methanol and nitro-methane? Because the engine can produce more torque with smaller lighter engines. Not that we should be fooling around with nitro-methane, but you can get a lot of benefit from either ethanol or methanol, but only if you shrink the engine.