Running on Corn: Why Ethanol Is Bad for Your Car

 Joe Raedle/Getty Images

Joe Raedle/Getty Images

If you’re a motorcyclist, chances are you’ve heard of ethanol before and you’ve a vague idea that it’s not good. If you’re not, you’ve probably seen the words “may contain up to 10% ethanol” emblazoned on a fuel pump the last time you got gas. Either way, there’s likely plenty you don’t know about this seemingly mysterious substance in your gasoline.

Ethanol is a corn-based alcohol that’s been touted as a way to reduce petroleum consumption with the benefits of making the U.S. less dependent on foreign oil while simultaneously making vehicles more environmentally friendly. Both of these claims are dubious for various reasons, but what’s rarely mentioned by ethanol’s proponents are the negative effects it can have on a vehicle’s engine and fuel system. E10, a mixture of 10% ethanol and 90% gasoline, is the most readily available fuel across the country today. In recent years, a political fight has been waged around whether or not to bump the ethanol content up to 15% (E15).

Photo by Justin Sullivan/Getty Images

Justin Sullivan/Getty Images

Ethanol has a few less than desirable properties that make E15 problematic. For one thing, ethanol contains only about two thirds of the chemical energy in an equivalent amount of gasoline. Aside from reducing overall fuel economy (negating some of ethanol’s environmental benefit), the lower energy density can cause certain motors to run too lean. Small engines and motorcycles are particularly vulnerable to this, and some manufacturers will void the warranty if E15 is used.

Sean Gallup/Getty Images

Sean Gallup/Getty Images

Another strike against ethyl alcohol is that it’s hygroscopic, which means it absorbs water from the air around it. This can cause a number of problems, not the least of which is that the water and ethanol can separate out from the gasoline. This can cause serious damage if ingested by the engine.

Ethanol also has an adverse affect on many fuel system components. Metal parts may corrode in the presence of ethanol (potentially fouling the fuel filter and/or pump). Rubber and plastic can swell or lose their structural integrity causing seals to leak or fail. Some fuel system additives can reduce these problems but none can eliminate them completely. Most modern fuel systems are designed with a 10% ethanol blend in mind and should be able to handle E15 as well. Older cars and motorcycles, however, may suffer from a variety of ethanol related issues ranging from minor to severe.

Scott Olson/Getty Images

Scott Olson/Getty Images

Why don’t we just do away with ethanol if it’s as bad as all that, you may ask. Well, it’s not that simple. In fact, there’s quite a bit of politics involved. Corn producing regions of the country love ethanol because it drives corn prices up. On the flip side, states with large cattle industries hate ethanol because it drives up their feed costs. Perhaps most concerning is that manufacturing ethanol for use in cars reduces the amount of corn available on the world food market, driving up costs and diminishing the amount available to the developing world. Environmental activists continue to point to ethanol’s yet to be realized potential for taking a chunk out of green house gas emissions. However, depending on how it’s grown and manufactured, ethanol can actually produce more harmful byproducts than gasoline.

In spite of all the controversy, the future of ethanol as a fuel is bright. Already the biofuel’s negative properties are being successfully compensated for with newer fuel system and engine design (many vehicles can now run on up to E85). And while most ethanol is produced from corn here in the U.S., other countries are using sugar cane or even tree clippings, grasses, and other non-food crops to develop similar fuels. This has the potential of eliminating the competition between the food and fuel markets once and for all. After all, when produced sustainably, ethanol can be as much as 90% greener than gasoline. Still, as biofuels continue to evolve, owners of cars and motorcycles made prior to 2000 will have to keep looking for those few and far between stations that still offer ethanol-free gas.

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