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% ethanol to 90% gasoline, 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.