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New Coalition Argues for Caution on Increasing Basic Ethanol Blend in Fuel Supply

A new coalition of national consumer, manufacturing, and gasoline retailer associations that consume or sell gasoline and ethanol-fuel blends recently formed with the mission to assure the “safe and successful introduction” of new bio-based and other alternative fuels. Most immediately, this means slowing down increasing Congressional movement toward shifting to a higher ethanol blend (20%) in the general national fuel supply (as opposed to E85 blends for designated flex-fuel vehicles).

The Alliance of a Safe Alternative Fuels Environment (AllSAFE) scored a win last week when the House Energy and Commerce Committee added an amendment to its energy bill requiring the US Environmental Protection Agency to undertake a public notice and comment process and approve or deny new renewable fuels and fuel additives within an expedited time-frame.

A similar amendment, however, was blocked during the Senate floor vote on its energy bill.

At its formation, AllSAFE released a report on the potential impacts of mid-level ethanol blends (fuels with more than 10% ethanol) on the existing pool of engines, vehicles, boats and equipment—i.e, both on-road and off-road applications, from boats and all-terrain vehicles down to leaf blowers and chainsaws.

There are significant known and unknown technical issues associated with changing the US conventional motor gasoline pool to accommodate higher than E10 blends. While some of these may be surmountable with additional research and the resultant use of new materials and engine/equipment designs, these can only be implemented in new equipment and with proper lead time. Important data gaps aside, with present knowledge, it is likely that there will be adverse, large-scale impacts if higher than E10 is required as motor gasoline for the existing fleet of on-road and off-road equipment, particularly the latter. Minimizing these likely adverse impacts on existing equipment and vehicles would require significant and expensive adaptation and mitigation measures.

—Dr. Ranajit Sahu, report author

Some of the changes  in fuel properties due to the addition of ethanol to gasoline the report covers include:

  • Change in octane number.

  • Change in fuel volatility (as measured through several properties, including vapor pressure,  vapor-liquid ratio, and the temperature-distillation curve). Of the issues caused by fuel volatility, the primary concern that occurs at elevated ambient temperatures is vapor lock, according to Sahu. Vapor lock is a condition where the fuel in the engine’s fuel delivery system vaporizes preventing the required volume of fuel to be delivered. Increasing the ethanol concentration beyond E10 “is likely to increase the likelihood” of vapor lock for open loop fuel control system engines typically used on older vehicles and most off-road engines. “Even in the closed loop engine systems used in some off-road engines and in most late-model vehicles, there remains the likelihood of vapor lock.”

  • Change due to the enleanment effect of ethanol. Because ethanol contains oxygen, when blended with gasoline it changes the stoichiometric air-to-fuel ratio of the blend. This is about 14.7 to 1.0 (on weight basis) for gasoline, but 14.0-14.1 to 1.0 for an E10 blend  because oxygen is contained in the ethanol and because some of the hydrocarbons have been displaced. The engine design anticipates that the fuel utilized will match the air-to-fuel ratio characteristics utilized in the engine design and calibration.

    Because ethanol blended fuels require more fuel for the same amount of air to achieve stoichiometric conditions, the fuel system must adapt by introducing more fuel or the desired mixture is not achieved. The effect of this type of fuel change on an engine is called “enleanment.”

    The effect of enleanment depends on engine design and how fuel is metered into the engine.

  • Change in the energy density.

  • Effect on water solubility and phase separation. In some situations, ethanol/gasoline blends might absorb water vapor from the atmosphere, leading to phase separation. Such problems are of greater concern for engines with open-vented fuel tanks that are operated in humid environments, such as marine engines.

  • Effect on material compatibility.

  • Effect on emissions.

Sahu notes the number of changes that Brazilian automakers implemented in their vehicles to support the use of higher ethanol blends (E20) to accommodate higher ethanol blends. 

It should be noted at the outset that ASTM has a standard for E85 which covers formulations ranging from E70 to E85. However, there are no standards for mid-level blends between E10- E70. Without standards, these formulations are being made on an ad-hoc basis by users, as needed typically by splash blending denatured ethanol with some type of base gasoline. Therefore, there is no comparability between properties of these mid-level blends made by various users. is important to remember that US emission standards are more stringent than those in Brazil. For US vehicles, manufacturers select oxygen sensors and onboard diagnostic (OBD) systems specifically to cover the expected range of oxygen in the exhaust gas. If the fuel ethanol pushes the exhaust oxygen content outside the range of the oxygen sensor, the vehicle’s OBD system won’t work properly and may erroneously illuminate or fail to illuminate the dashboard warning light.

In addition, manufacturers must calibrate vehicle and product systems to the expected fuel to ensure the proper air-fuel ratio for both emissions and performance purposes. In the US, off-road engines are also regulated for emissions regardless of their size or equipment that they power. Generally, the off-road engines do not utilize oxygen sensors and computer controls to adjust fuel delivery by a closed loop system. In many products, emission compliance has dictated air-to-fuel ratio controls that are a delicate balance between being too rich and, therefore, out of compliance, or too lean, resulting in performance or durability problems.

AllSAFE is made up of the following national associations that represent: (1) consumer and commercial users of ethanol blends and other fuels in their equipment and vehicles; (2) manufacturers of boats, vehicles, engines and equipment; and (3) gasoline retailers that sell gasoline and ethanol-fuel blends, including the existing 10% ethanol blends.

AllSAFE members
Alliance of Automobile Manufacturers
American Motorcyclist Association
Association of Marina Industries
Association of International Automobile Manufacturers
Boat Owners Association of the United States
Engine Manufacturers Association
International Snowmobile Manufacturers Association
Motorcycle Industry Council
National Association of Convenience Stores
National Marine Manufacturers Association
Outdoor Power Equipment Institute
Personal Watercraft Industry Association
Professional Landcare Network
Specialty Vehicle Institute of America




How is there no mention of butanol? 100% butanol is not likely to be approved for existing engines, but it would be nice to know what the highest allowable threshold would be.


I question this coalition's interest in safety when their constituent groups all stand to lose money from changes in their businesses-as-usual. They have conflicts of interest, so they shouldn't be acting like they are proteting public safety or helping the environment. How safe is global warming? Weren't these the same lobbyists that were mocking the inconvenient truth that we haven't been addressing?


Angelo (or anyone else) -
What makes you believe that 100% butanol is not likely to be approved for existing engines?


P.S. per

"Unlike ethanol, you can fill your car-old, new, whatever-with a tank- full of butanol and it will run without modifications, as far as you go on a tank of regular unleaded. In short, it's an ideal gasoline replacement. Do you want a renewable fuel that lets you keep the car you have now? Butanol is the fuel of choice."

(among many other such articles on Butanol)


Because the people in charge of approvals have ties to big oil.


Allsafe, I appreciate what you are doing, but what if we could develop another way to power cars completely different than ethanol blend fuels? How about a car that runs on no biofuels and has 0% emissions by 2007 or 2009? It sounds hard to believe but it's here now. By 2014 we could start seeing levels of emissions drop 10% to 20%. If you are interested, please email me. I could always use the help to bring my development to the market. You can email me at [email protected]


Let's work together in conserving our energy. Use more windmills, solar, and water. What if there is a unit that can supply a whole house with endless power and 0% emissions. It is also portable and runs like a standby generator all the time. No noise and it wouldn't cost more than a standby generator. You could forget power companies and we would have independance from them. We could cut back on emissions from power plants. If interested, email me. I could always use the help putting my development on the market. Email - [email protected]


Butanol still is not quite perfect, and at very least it would mess with the fuel gauge.

That said a Butanol 17% blend could be done with total compatibility.


Butanol has yet to prove itself, really. And it's actually harder to produce than ethanol at this point. BP and DuPont are supposed to be testing it this year, and until we know the results of this program we shouldn't hold our breath.


Anybody have any figures on how many older vehicles there are on the highways out there? How many of those millions do you suppose can't afford to have their vehicles converted over so they can use ethanol?
For newer (flexfuel?) vehicles and those older vehicles that can spend the money and time to have their vehicles converted, how many are going to be very comfortable helping to pay the $billions necessary for the change in infrastructure required to get the ethanol to the pumps?


"What makes you believe that 100% butanol is not likely to be approved for existing engines?"

While they very well may be completely unfounded, I've read about some issues running 100% butanol in cold weather. I seriously hope they are inaccurate, but my point was that it would be nice to find out either way.

Additionally, it would also be nice if they considered ethanol/butanol blends. From what I've ready, ethanol does have a more profound increase on thermal efficiencies. One particular study concluded that blends as low as 30% ethanol (in gasoline) might give you 90% of it's benefit in thermal efficiencies (assuming an engine was optimized for it). Other studies that require keeping the ethanol in a separate tank and injecting it selectively suggest that percentage can be even lower.

So, maybe a 70% butanol/30% ethanol blend would be optimal? Again, I have no idea, but it would be nice to know what the optimal alcohol-based energy carrier would be, even if it is a blend.

P Schager

This is really the same inertia problem they had in the 1980's when they introduced compatibility for the first 10%. It's too bad they didn't start much earlier. However I doubt the vehicles that were designed with 10% in mind will be much affected by the change; it is probably mostly just carmakers being lazy and not wanting to do their part. 20% compatibility should be a requirement in next year's cars, though, and then if the makers don't actually do anything we'll pretty well know the older vehicles will be fine. Possibly with time-of-year restrictions on delivered concentration.

The best solution, so that the migration to biofuels can be reasonably unimpeded is to have pumps made, I call them Mixer Pumps, that would mix the blend to order for the car. Say start out with 10% ethanol base stock and add another 10% on dispensing unless the buyer pushes the decline button. Or there is an RFID tag at the fuel filler that the pump reads for fuel compatibility information, or you have an optical sensor for a colored ring label around the fuel filler hole, or a network connection pump-to-car. Note that one pump serves around 50 cars, so the cost of adaptation here would be low. Price should be by MJ or GGE rather than by volume.

The pump could have a variety of options, so it can give the best thing for each car. Some cars might only spec 10% ethanol, but you could add another percentage in butanol and still have little chance of the car noticing. (Butanol's octane isn't great, so you still want ethanol.) The network should tell the car what it received so that car's computer can read out how your efficiency is doing without confusion from different energy density mixes.


I'm a pretty smart guy, but that even confused me. Don't forget, most drivers don't even know where the radiator fill cap is located, and wouldn't know the blended fuel ratio of their car from swamp water.

Knowing my wife, she would probably go "eney meny mighty mo and punch a button.
Boy, am I glad she doesn't use this site!

Fran Barlow

A couple of quick points on butanol and ethanol

1. Butunal can use waste cellulose as feedstock far more easily than can ethanol

2. Per acre, you'll get a better energy yield in useable fuel from butanol

3. The high cetane number of butanol(CN25) makes it possible to use it to extend diesel fuel, and allows vegetable oil to be run as diesel

4. It can be used to improve the cold starting of an ethanol powered car.

Ethanol, on the other hand, need not be less fuel efficient than gasoline. Ethanol has a much higher octane number than gasoline, and can operate on much higher compression ratios without engine knock being a risk. More compression = more thermal efficiency and more motive power. All lese equal, you do use a slightly higher quantity of ethanol in the mix, but if you back off the throttle you can get more with less. Potentially, you could have a smaller lighter higher compression higher octane engine using less ethanol but producing the same performance and superior fuel economy with lower cost fuel and lower emitting fuel.

All of the alcohol fuels run cooler and this extends engine life, as does the fact that you can generate the same power at lower RPM (and thus turn over the engine less often per unit of distance). On the other hand, ethanol is tough on plastic and rubber seals, whereas butanol is not. Ethanol can break down coke deposits in gasoline driven engines.

I see butanol as the best option, especially if sourced from waste biomass, but ethanol remains a perfectly plausible alternative if vehicles were designed and mass produced with ethanol use in mind, or if engine modification was not prohibitively expensive or technically too challengiing.



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