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E85-PumpIt's no secret that fuel alcohol is a hotly debated topic in our community. Ethanol is hailed as the future of sustainable fuel for automotive engines, but it has been known to cause issues with older vehicles. I for one am very hopeful and optimistic about the future of Ethanol as a motor fuel, but I can't deny that it has been a thorn in my side over the last few years when it comes to fuel system maintenance. Ethanol is a fundamentally different beast than gasoline, but may be our best bet as far as creating sustainable, home-raised fuel.

Ethanol is an alcohol. Indeed it is the alcohol we refer to when we are discussing beverages. It is produced by sugar fermentation, though it can also be produced as a petroleum by-product. A lot of what makes ethanol so attractive is the fact that it can be produced biologically, as from sugar cane in the case of Brazil, or perhaps from abundant corn production in the US. Although production has not yet been perfected, it is one of the more easily attainable bio-fuels, and is being closely considered by all parties involved.

Ethanol = High Octane

Ethanol has a higher resistance to pre-ignition than gasoline does - it can be thought of as having a very high octane figure. It is thus possible to design ethanol based engines with higher compression ratios in order to extract more energy from the fuel, which helps compensate for the drastic loss of energy density in ethanol versus gasoline. This difference in energy density poses a problem for engines which are designed to run on both fuels, as design considerations for ethanol and gasoline are rather different. Therefore, much of the actual engine design cannot be truly optimized for either fuel without complex electronics and controls. This, plus the fuel system specifications of Ethanol, account for much of the increased price of a “Flex-Fuel” vehicle.

Possibly the biggest issue with ethanol at this point, besides availability, is the fact that it is a rather chemically “friendly” substance. Ethanol is hygroscopic, meaning that it absorbs water from the atmosphere. Water is very harmful in the fuel system, as it can cause clogging, corrosion, and damage to finely made parts in the injection system. Besides that, there are many substances that are soluble in ethanol- that is, ethanol will dissolve and carry with it many other substances, some of which are quite corrosive and can do tremendous damage to a typical gasoline fuel system. Vehicles that are designed to burn ethanol must therefore have specially designed fuel delivery systems to account for these differences.

Ethanol and gasoline blends approach 100% ethanol

Finally, exhaust after-treatment becomes a consideration as the blends of ethanol and gasoline approach E100 (100% ethanol). Exhaust emissions are somewhat different between the two fuels, necessitating different methods of catalytic reduction, and even policy change to keep up with the changing trends of vehicle emissions. Analyses of the environmental effects of ethanol from biomass, including everything necessary to grow, harvest, process and refine, have shown the production of ethanol to be favorable if the technology of production can keep up with the demand.

Although we still seem to be a ways away from a solution to our oil problems, new technologies and concepts are being presented every day. If a newer and more practical technology does not take away ethanol's “thunder”, it is safe to say that we will continue to develop ethanol combustion technology and incorporate it more heavily into future automobile production. For the DIY mechanic, this may complicate things, as 100% gasoline fuel is becoming more difficult to find, and our older automobiles may not be keen to the change. It is very likely that as this technology progresses, new products will be introduced to make ethanol an easier transition for those of us who refuse to give up our timeless treasures.

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Dan BullmoreDan Bullmore is a physicist and engineer from Houston, TX. Preferring the old to the new, Dan has owned many examples of Mercedes and Volvos and has devoted much of his time to maintaining and understanding them.


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Written by :
Dan Bullmore

Dan Bullmore is a physicist and engineer from Houston, TX. Preferring the old to the new, Dan has owned many examples of Mercedes and Volvo vehicles and has devoted much of his time to maintaining and understanding them.


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