28 January 2007

Ethanol-blended gasoline: Coming soon to a pump near you

Lacing gasoline with alcohol (ethanol, commonly called ethyl or grain alcohol) is nothing new. Ethanol fuel blends were used as early as the Model T Ford days, both as a cheap additive to stretch gasoline supplies, and as an octane booster – until replaced by tetraethyl lead around the end of World War I. In 1975, when the United States phased out leaded gasoline, ethanol’s prospects grew brighter as demand increased.

All gasoline currently sold in Minnesota contains ethanol. The blend is 1 to 10 or a 10 percent mixture. Originally nicknamed gasohol, this mixture is now referred to as E10, there being other blends ranging from 5 percent (E5) to 85 percent (E85). Both houses of the Minnesota legislature have passed bills that could require gasoline sold in that state to contain 20 percent ethanol (E20). Further, the Federal government’s Energy Policy Act of 2005 mandates a production capacity increase for ethanol from the current 4 billion gallons per year to 7.5 billion gallons by 2010.

Why all the interest in gasoline mixed with ethanol, and what are the likely consequences for our older cars?

Ethanol’s appeal is that it can be produced domestically, fits easily into the present distribution system, and provides nearly the same energy per gallon as pure gasoline. Enhancing its appeal, ethanol can be produced either from crops or agricultural/industrial waste. At the core, ethanol blended gasoline claims two primary benefits: higher prices to farmers (primarily for corn) and reduced reliance on unstable foreign oil sources.

However, using the yardstick of energy in to energy out, ethanol is a loser; it takes more energy (in the form of fossil fuels) to grow the corn, make and blend the ethanol, and, finally, burn it for energy that to use fossil fuels alone. So why the rush to ethanol? At the top of the list, legislators find helping farmers and offering an alternative to our foreign oil sources to be both popular and patriotic – keys to being re-elected. There are a few technical reasons as well. Since the lead phase-out, MTBE (methyl tertiary butyl ether) has been used as a fuel oxygenate, but MTBE is a known carcinogen, and ethanol, which can be a substitute, is not.

It is widely recognized that alcohol packs less energy than gasoline, so the question becomes how much bang do you loose with your buck when you buy alcohol-blended gasoline?

The reality, at least with the milder blends, is different than you’d suspect just from looking at the raw numbers. Ethanol alone produces 76,100 btu of energy per gallon while gasoline contains from 108,000 to 117,000 btu/gallon. But, keep in mind, we’re not talking about ethanol alone, but ethanol/gasoline blends. Although a 10 percent ethanol blend has 2 percent less energy content than gasoline, it’s the energy range within gasoline itself where the more noticeable energy – and therefore mileage–loss occurs.

Refineries brew different grades of gasoline for winter and summer driving. The difference in energy content between winter and summer grades can vary by as much as five percent. Thankfully, most of us enjoy driving our old cars in summer months – the time that gasoline packs its greater punch. But, you lose more just by buying gasoline in wintertime than you do by filling up in summer months with E10. There is hope that as ethanol competes with gasoline as a fuel source, lower prices will result.

The presence of ethanol-blended gasoline is sure to increase causing us to fret about the consequences of this fuel used in older cars. It’s possible that pumps with pure gasoline will still be available for vehicles 20 years old and older – that’s what the Minnesota legislature is contemplating as it prepares to mandate an E20 blend. Where the E85 blend is available (currently E85 can only be found at some 650 of the 170,000 retail gasoline stations in the United States), it will be used only in specially equipped, newer vehicles. But with E10 becoming common, especially in the Midwest, what are the consequences of its use in older vehicles?

Not to worry, say most fuel authorities. Any of today’s gasoline formulations, not just ethanol blends, is more aggressive toward elastomers (such as rubber fuel lines, fuel pump diaphragms, and rubb4er seals under carburetor float needles) than the gasoline we pumped 40 years ago. So, even though a mild ethanol blend could potentially harm rubber fuel system parts in older cars, this is not seen likely – one reason being any fuel system parts replaced since the early 1980s are compatible with today’s fuels.

There is a risk, however, of ethanol’s cleaning effect loosening sediment in old fuel tanks and plugging fuel lines or filters. (When using an ethanol-blended fuel, it’s a good idea to have an extra fuel filter or two on hand.) Most at risk are older vehicles whose fuel tanks have been sealed with that sloshy goo sold as a fuel tank liner. Ethanol at work on this stuff could be a real nightmare.

If you own a vehicle built before the mid-1980s, stay away from the richer ethanol blends, using plain gasoline where available. If E10 is the only choice, and the fuel tank is known to contain sediment or has been sealed, plan to replace the tank or have it boiled and re-sealed with product that’s impervious to alcohol.

 

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