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15.08.2018 Солнце в сеть

Производство оборудования и технологии

Gasoline Ethanol Blends

Currently, a number of countries around the world use fuel grade ethanol as a blend-in transportation fuel. Ethanol has been added to gasoline since the late 1970s in the United States. Since that time, US fuel grade ethanol production capacity has grown to over 13.9 bil­lion gallons per year (2011) [2] and production volumes continue to increase. Until the late 1980s ethanol’s primary role in the fuel mar­ket was that of an octane number enhancer and it was viewed as an environmentally sound alternative to the use of lead in gasoline. With its 112.5 blending octane value (R+M)/2, ethanol continues to be one of the most economic octane enhancers available to the refiner or fuel blender. In the late 1980s some states began to use ethanol and other oxygenates in mandatory oxygenated fuel programs to reduce automobile tailpipe emissions of carbon monoxide (CO). Fuel oxy­genates, such as ethanol, add chemical oxygen to the fuel, which pro­motes more complete combustion, thereby lowering CO emissions. Hydrocarbon (HC) exhaust emissions are also often reduced, but to a lesser degree.

The success of these early oxygenated fuels programs led to a similar national program in the 1990s, the Clean Air Act amend­ments. These amendments required that beginning in November 1992, all CO non-attainment areas implement mandatory oxygen­ated fuel programs during certain winter months. The oxygen­ated fuels program has been tremendously successful. Most of the original non-attainment areas have now achieved compliance, although some continue to require oxygenated fuels to main­tain compliance. Then, a series of legislature such as the Energy Independence and Security Act of 2007 led to increased consump­tion of ethanol aimed at reducing fossil fuel consumption and boosting energy security.

The use of pure anhydrous ethanol in internal combustion engines (ICE) is only possible if the engines are designed or modified for that purpose. However, fuel grade ethanol with less than 1% water can be blended with gasoline (or petrol) in various ratios for use in unmodi­fied gasoline engines, and with minor modifications can also be used with a higher content of ethanol. Low-ethanol blends, from E5 to E25, are also known as gasohol, though internationally the most common use of the term refers to the E10 blend. The most widely known blends in the United States are E10, E15 and E85.


The E10 blend is a low-level blend composed of 10% ethanol and 90% gasoline. It is classified as "substantially similar" to gasoline by the U. S. Environmental Protection Agency (EPA) and is legal for use in any gasoline-powered vehicle. The use of E10 was spurred by the Clean Air Act amendments of 1990 and subsequent laws, which mandated the sale of oxygenated fuels in areas with unhealthy levels of carbon monoxide. This kicked off the modern US ethanol industry growth. Today, E10 is sold in every state in the United States. In fact, most of the US gasoline contains up to 10% ethanol to boost octane, meet air quality requirements, and most importantly satisfy the renewable fuel standard. However, E10 does not qualify as an alternative fuel under the Energy Policy Act of 1992 (EPAct).


Another low-level blend composed of 15% ethanol and 85% gasoline is E15. In response to a request by ethanol manufactur­ers under the Clean Air Act, the U. S. Environmental Protection Agency (EPA) granted two partial waivers that taken together allow but do not require the introduction into commerce of gaso­line that contains greater than 10 volume percent (vol%) ethanol and up to 15 vol% ethanol (E15) for use in model year (MY) 2001 and newer light-duty motor vehicles, subject to certain condi­tions. On October 13, 2010, EPA granted the first partial waiver for E15 for use in MY2007 and newer light-duty motor vehicles (i. e., cars, light-duty trucks and medium-duty passenger vehicles). On January 21, 2011, EPA granted the second partial waiver for E15 for use in MY2001-2006 light-duty motor vehicles. These deci­sions were based on test results provided by the U. S. Department of Energy (DOE) and other test data and information regarding the potential effect of E15 on vehicle emissions. With the EPA’s June 15, 2012, approval of a number of companies misfueling mitigation plans, the EPA has acted on each of the Clean Air Act steps required to bring E15 to market. Some companies have now met all of the Clean Air Act requirements related to E15 and may lawfully introduce E15 into the marketplace. While E15 does not qualify as an alternative fuel under EPAct, it does help meet the federal Renewable Fuel Standard. In a more recent development, on February 7, 2013, EPA approved a new blender pump configu­ration, submitted by the Renewable Fuels Association, for general use by retail stations that wish to dispense E15 and E10 from a common hose and nozzle.


A mixture of 85% ethanol and 15% gasoline, E85, is generally the highest ethanol fuel mixture found in the United States and sev­eral European countries, particularly in Sweden, as this blend is the standard fuel for flexible-fuel vehicles (FFVs). This mixture has an octane rating of about 105, which is significantly lower than

pure ethanol, but still higher than normal gasoline (87-95 octane, depending on country), and is a high-level gasoline blend that qualifies as an alternative fuel under the EPAct. It can be used in flexible-fuel internal combustion engines that run on either E85 or gasoline, but cannot be legally used in conventional gasoline-pow­ered vehicles.

The use of E85 and the number of flexible-fuel vehicles (FFVs) continues to increase in the United States. There were approxi­mately 8.35 million E85 FFVs in the US in 2010. Three big auto man­ufacturers, General Motors, Ford and Chrysler, each offered several FFVs models in 2010. Mercedes Benz, Nissan and Toyota offered one FFV engine package. In total there were 34 different E85 FFV models for sale in the US in 2010, compared to 19 models in 2004 and just 2 models in 1998. In addition, there were 2,318 E85 stations as of December 2010, as compared to fewer than 200 in 2003 [3].

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