Automakers have filed a lawsuit against the EPA's decision to make
E15 (gasoline with 15 percent alcohol) legal for all cars after 2007.
They argue that, among other problems, the blend could damage the
engine. Wait, moonshiners used to run their cars on 190-proof hooch. Can
ethanol really do damage to an engine? Yes. Here's how.
Most people realize that all of us
burn gasohol—a mixture of gasoline and alcohol—in our
cars. Just about every gallon of gas pumped today contains as much as 10
percent domestically produced ethanol. Gummed-up fuel systems, damaged
tanks
and phase separation caused by stray moisture infiltrating fuel systems
have plagued many consumers since this mixture debuted, and the problems
will
only get worse if government policy to increase the proportion of
ethanol to gasoline is implemented. Don't get me wrong: Gasoline diluted
with ethanol is a perfectly acceptable motor fuel when it's stored
properly, dispensed promptly and burned in vehicles and power equipment
designed to handle it. Which, unfortunately, is not always the case.
Moonshine It's Not
That 90:10 mixture of gasoline and alcohol is referred to as E10, while a different blend of 15 percent gas and 85 percent alcohol is sold regionally as E85. On this scale, straight petroleum-based gasoline is referred to as E0. Most gasoline dispensed from pumps in this country is as much as 10 percent ethanol, distilled from corn grown in the Midwest. This alcoholic cocktail was originally mandated by the EPA as a replacement for MTBE (methyl tertiary butyl ether), an oxygen-bearing petroleum-sourced chemical that was added to pump gasoline starting in 1979 to reduce carbon monoxide emissions in some regions that had problems meeting government air-quality standards. The oxygen in the MTBE (and ethanol) molecules can substantially reduce CO emissions in vehicles without modern closed-loop fuel-injection systems, which were introduced starting in the '80s.
Soon after, MTBE started turning up in groundwater, affecting the taste and smell of drinking water, so ethanol was substituted. (Shockingly, MTBE isn't considered toxic or even carcinogenic in the concentrations found in groundwater, but still.)
However: If the beneficial effects of oxygenated fuel have largely been bypassed by modern feedback-loop injection systems, which control the air-to-fuel ratio much more closely, why is ethanol still in your fuel? Because the second President Bush made a decision to offset some of our dependence on foreign oil with domestically produced alcohol, and the Corn Belt senators agreed. Ethanol plants have mushroomed, ramping up U.S. production from 1.77 billion gallons in 2001 to 10.75 billion gallons in 2009. Politics aside, odds are near 100 percent that there's as much as 10 percent alcohol in the gasoline you're pumping into your car and that 5-gallon can you use to fuel all your other gas engines.
Keeping Water Where It Belongs
The ethanol in your gas tank is uniformly dissolved in the gasoline. Alcohol tends to absorb and hold water, and in concentrations in the tank up to about 0.6 percent, any water remains in solution, presenting no problems. (Yes, there are other problems with alcohol in the fuel system, but we'll get to them later.) How does water get into the fuel tank? It's possible that water dripped into the tank at the gas station or refueling depot, or a stray raindrop or snowflake made its way into your tank or jerrycan, but most water infiltration is from condensation. As the temperature in a tank changes, air has to be vented in and out or the tank will bulge or split. Incoming air carries moisture. When the H2O in the gas gets above a critical percentage—its saturation point—all of the water and alcohol drops out and settles into the bottom of the tank. This is what chemists call phase separation; the various components of the fuel are no longer a homogeneous mixture.
But phase separation does not occur only from increased water concentration, which is actually unlikely in a modern, emissions-sealed automotive fuel system. The temperature of the fuel is a factor as well. Here's the scenario: You fill up the car or gas can with fuel that, for a variety of reasons, is near its water-saturation point and at 60 degrees. Overnight, the temperature drops 20 degrees, and all the water and alcohol settle out even though no extra water has crept in. Guess what? The engine won't run when the fuel pickup is sucking up the alcohol–water mix.
Worse yet, the gasoline remaining above the water has probably lost three octane points, because today's gasoline relies heavily on the high-octane equivalence (130) of alcohol to achieve its octane rating. It's also missing a bunch of additives that stayed in the alcohol—so the entire tankful should be drained and disposed of as hazardous waste.
And no, adding more alcohol, in the form of fuel-line de-icer, lacquer thinner or cheap vodka will never restore that gasoline to usefulness. You don't want to add yet more alcohol, lest the increased concentration turns your carburetor float to Jell-O. The only acceptable way to attempt to save the gas in the tank is to add a large amount of gasoline that's got a very low moisture content. Problem is, there's no good way to tell if pump gas has a little or a lot of water on board. You stand the chance of having twice as much phase-separated, unusable gasoline as before. Better to dispose of the whole tankful.
Other Alcohol Issues
Alcohol is corrosive and can degrade plastic, rubber or even metal parts in the fuel system that weren't engineered to use alcohol-bearing fuel. Consequently, that antique Evinrude outboard or '60s lawn tractor you bought at the swap meet might need some upgrading to stay together on today's gas. That means corrosion-resistant tanks, alcohol-tolerant rubber lines, seals and fuel-pump diaphragms, and plastic fuel-system parts that won't swell up in the presence of alcohol. Vintage boats with internal fiberglass tanks often have issues with the coating inside the tank failing, sometimes requiring massive structural modifications. Highly tuned two-stroke engines will run leaner (and consequently hotter) on the lower Btu/gallon alcohol mix, potentially leading to melted pistons and scuffed cylinder walls. Alcohol will also scour varnish and deposits out of the fuel system that have remained in place for years, which will eventually wind up in the filter or main jet, choking off the engine's fuel supply. Worse yet, the alcohol itself oxidizes in the tank and produces a tenacious brown glop that's far more damaging to fuel systems than the varnish we're used to seeing in pure petroleum fuels. In warmer weather, you can see varnish starting to form within a month of dispensing fresh fuel into a vehicle tank or storage can.
Advice
The common question I get: Where can I buy alcohol-free gasoline? You probably can't, except at a very few stations, and odds are it's very expensive high-octane racing fuel that's not legal for road use.
To avoid phase separation, avoid long-term fuel storage. Trash that old 5-gallon can with the rag stuffed into the filler neck and trade up to a 2-gallon can with a decent, vented cap. I used to recommend storing outdoor power equipment, boats, ATVs and motorcycles with full tanks to prevent rusting. Now I recommend draining the tank, running the engine till it quits and then fogging the inside of the tank and the cylinder with oil to prevent corrosion. No E10 in the tank equals no water absorption and no phase separation.
We've always recommended using fuel-stabilizer products for gas-powered vehicles or tools that aren't regularly used. E10 makes that advice even more compelling. We've tried products formulated for blended gasoline from Star Tron, Eastwood and Sta-Bil. There are others. Beware of products that claim to prevent phase separation: It's unlikely that they can eliminate the phenomenon, although some products do claim to delay it.
And why on earth do we need E15?
It's the Blend Wall. By passing the Energy Independence and Security Act of 2007, Congress mandated that 15 billion gallons of corn ethanol be blended into the nation's gasoline supply by 2015. Last year's U.S. production of 11 billion gallons will ramp up to 22 billion by 2012. The amount of alcohol in gas must therefore be increased. Jeff Broin, CEO of Sioux Falls, S.D.–based Poet, the nation's largest ethanol producer, says that the ethanol industry would like to increase that 15 percent to 20 percent—or more.
All of which is okay in vehicles engineered to use it, but what about those that aren't? Broin suggests that in the future, "consumers will be able to dial up the concentration of ethanol they'd like to burn at the pump, from zero to 20 percent or more, just like they choose their octane rating today." That's exactly what those of us with older cars, tools or toys will need. Problem: Getting different blends to the consumer will require massive infrastructure changes. Gasstation owners will have to upgrade existing pumps to handle E15 and higher concentrations. The blending pumps Broin is suggesting will cost more than a typical $20,000 conventional unit. In addition, station owners will have to install more tanks. An energy policy that mandates more domestic production sounds like a great idea. But sneaking more ethanol into the supply stream at the expense of people who rely on their cars, boats and outdoor power equipment might better be left to the marketplace and not to bureaucrats.
Tidak ada komentar:
Posting Komentar