why do they put ethanol in gas

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In the early 1990s, the United States government issued a series of amendments to the Clean Air Act that included the requirement to use oxygenated gasoline (minimum oxygen content of 2. 0-percent by weight for reformulated gasoline in ozone non-attainment areas, for what it's worth) to help the fuel burn more completely in combustion. One of the favored oxygenates was methyl tert-butyl ether, or MTBE. This chemical compound was chosen due to its low price and because it helped mixers generate higher octane ratings. All seemed well until California discovered in 1995 that MTBE was showing up in high concentrations in drinking water, which was traced back to spilled gasoline and leaky underground containers.


Ethanol was widely seen as a safer replacement for MTBE and its use was pushed by the agricultural industry here in the States. So, now that we know why regular gasoline probably has at least some ethanol in it, the next logical question is do you need to be worried about it? The answer is a qualified no. Today's cars and trucks are all fully capable of running on E10, a blend of 10-percent ethanol and 90-percent gasoline.


Sophisticated computer systems and sensors constantly monitor the engine and the exhaust to be sure that everything (i. e. , the air-fuel mixture) is kept at its optimum level. How much ethanol is in gasoline, and how does it affect fuel economy? In 2015, about 13. 7 billion gallons of were added to motor gasoline produced in the United States, and fuel ethanol accounted for about 10% of the total volume of finished motor gasoline consumed in the United States. Fuel ethanol contains a that is added to ethanol to make the ethanol unfit for human consumption. Federal law requires that fuel ethanol contain at least 2% denaturant by volume, but the actual content in fuel ethanol may be higher.


Most of the gasoline now sold in the United States contains some ethanol. Most of ethanol blending into U. S. motor gasoline occurs to meet the requirements of the 1990 Clean Air Act (RFG Fuel) and the Renewable Fuel Standard set forth in the Energy Independence and Security Act of 2007. The U. S. Environmental Protection Agency (EPA) administers the requirements with the. There are three general categories of ethanol-gasoline blends: E10, E15, and E85.


E10 is gasoline with 10% ethanol content. E15 is gasoline with 15% ethanol content, and is a fuel that may contain up to 85% fuel ethanol. The ethanol content of most of the motor gasoline sold in the United Sates does not exceed 10% by volume. Most of the motor gasoline with more than 10% fuel ethanol content is sold in the Midwest where most of ethanol production capacity is located. Gasoline dispensing pumps generally indicate the fuel ethanol content of the gasoline. All gasoline engine vehicles can use E10. Currently, only and light-duty vehicles with a model year of 2001 or greater are, although some automakers have yet to approve the use of E15 in their vehicles.


Flex-fuel vehicles can use any ethanol-gasoline blends up to E85. The energy content of ethanol is about 33% less than pure gasoline. The impact of fuel ethanol on vehicle fuel economy varies depending on the amount of denaturant that is added to the ethanol. The energy content of denaturant is about equal to the energy content of pure gasoline. In general, vehicle fuel economy may decrease by about 3% when using E10 relative to gasoline that does not contain fuel ethanol. Last updated: April 6, 2016