What Is Ethanol?

By Deanna Sclar from Auto Repair For Dummies, 2nd Edition

All cars used to run on the same type of fuel, but now gas stations offer not only unleaded gasoline but alternative fuels, such as ethanol, diesel, biodiesel, and others. Ethanol in particular has started showing up at gas stations with more regularity. But what is ethanol?

Ethanol is an alcohol fuel that's distilled from plant materials, such as corn and sugar. Alcohol fuels have been around for years, typically mixed with gasoline in a blend also known as gasohol. E10, with a ratio of 10% gasoline to 90% ethanol, can be used in any internal combustion engine, and many oil companies already blend their fuels that way. Methanol, mostly used in race cars, isn’t popular for other vehicles because it isn’t as clean and it also relies on fossil fuels. The use of these fuels in higher proportions requires modification to the fuel storage and delivery systems on cars and trucks.

E85, a mixture of 85% ethanol to 15% gasoline, can be used in flex-fuel vehicles, and car enthusiasts have modified their vehicles to run on ethanol or methanol alone, with mixed results. One point that’s commonly overlooked is that alcohol is about half as energy-dense as gasoline, so you can only go half as far on a tank.

Because ethanol is biodegradable, nontoxic, and dissolves in water, E85 has been praised by the U.S. Department of Energy (DOE) as producing emissions that contain less carbon dioxide and carbon monoxide than emissions from vehicles that run on gasoline. As the supply of gasoline diminishes, the current E85 standards that require the mix to contain 15 percent gasoline are being challenged to allow a greater proportion of ethanol.

The major controversy concerning ethanol fuel concerns the sources used to produce it. Corn-based ethanol has disastrous effects on the price and availability of corn for food and other products. It also doesn’t produce as much energy as gasoline and requires fossil-fuels to grow, refine, and deliver it. Happily, cellulosic ethanol does not have those drawbacks. Because it is derived from the cellulose found in non-food agricultural and waste products, such as switch grass — a fast-growing plant that has a high yield of energy and requires little in the way of fertilization and other high-energy production costs — old newspapers, and other substances, it can compete with gasoline for fuel efficiency and not affect the price and supply of grains and other vital vegetation.

Vehicles that can run on two or more types of fuel are called flex-fuel vehicles (FFVs). (They’re also known as dual-fuel or multi-fuel vehicles.) The most popular FFVs can run on either gasoline or ethanol or a mixture of the two. Many people drive FFVs and don’t even know it! If you’d like to know whether your vehicle is an FFV, check your owner’s manual, look for a sticker inside the little door you open to add fuel, call your dealership, or go to the Fuel Economy Web site, which has a list of available flex-fuel vehicles.