![]() Because low levels of ethanol can cause gasoline to evaporate more easily, low-level ethanol blends can increase evaporative emissions in vehicles. Most of these emissions occur when the car is parked or refueling. Evaporative and Tailpipe EmissionsĮvaporative emissions are highly dependent on temperature, vehicle activity, and vehicle system materials. These studies are addressed in the Ethanol Energy Balance section. In addition to life cycle GHG emissions and petroleum use, numerous studies have examined the life cycle energy balance of ethanol. Depending on the feedstock, average emissions reductions of cellulosic ethanol compared to conventional gasoline range from 88% to 108% depending on feedstocks used. Using cellulosic ethanol provides an even greater benefit. As a result, FFVs running on high-level blends of ethanol produce less net CO 2 than conventional vehicles per mile traveled.Ī 2012 study by Argonne National Laboratory found that when these entire fuel life cycles are considered, using corn-based ethanol in place of gasoline reduces life cycle GHG emissions on average by 34%. Carbon dioxide (CO 2) released when ethanol is used in vehicles is offset by the CO 2 captured when crops used to make the ethanol are grown. Using ethanol as a vehicle fuel has measurable GHG emissions benefits when considering the life cycle steps required for gasoline. When comparing fuels, a life cycle analysis may focus on particular portions of a fuel's life cycle, such as from extraction-to-use, also referred to as well-to-wheels, to determine the merits or problems associated with each fuel. Life cycle analysis is used to assess the environmental impacts of all stages of a product's life, including raw material extraction, processing, manufacturing, distribution, use, and disposal or recycling. Today's emissions standards require ethanol/gasoline-capable flexible fuel vehicles (FFVs) to meet the same emissions standards as conventional vehicles, regardless of the fuel used. As with conventional fuels, the use and storage of ethanol blends can result in emissions of regulated pollutants, toxic chemicals, and greenhouse gases (GHGs). ![]() When blended with gasoline for use as a vehicle fuel, ethanol can offer some emissions benefits depending on vehicle type, engine calibration, and blend level. ![]()
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