New Insights to the Use of Ethanol in Automotive Fuels: A Stable Isotopic Tracer for Fossil- and Bio-Fuel Combustion Inputs to the Atmosphere (original) (raw)
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2014
This paper is based on the available evidence for the air quality impacts of using ethanol fuels in transport and also focuses on regulated and unregulated air pollutant emissions from vehicles running on ethanol fuels. Fuel options for reducing emissions include reformulating conventional fuels to reduce or increase particular components, or use of alternative fuels such as ethanol. Ethanol is a liquid alcohol that is manufactured by the fermentation of a wide variety of biological materials. These materials include grains such as wheat, barley, corn, wood, and sugar cane. Agricultural crops particularly grains are likely to be used in some countries because they have both high productivity and high levels of carbohydrates needed for ethanol manufacture. The review begins with a general overview of the air quality impacts of burning fuels in vehicle engines, listing the types of pollutants normally produced and their impacts on human health and the environment. The specific impacts...
Fuel, 2012
The study investigated the impact of ethanol blends on criteria emissions (THC, NMHC, CO, NO x ), greenhouse gas (CO 2 ), and a suite of unregulated pollutants in a fleet of gasoline-powered light-duty vehicles. The vehicles ranged in model year from 1984 to 2007 and included one Flexible Fuel Vehicle (FFV). Emission and fuel consumption measurements were performed in duplicate or triplicate over the Federal Test Procedure (FTP) driving cycle using a chassis dynamometer for four fuels in each of seven vehicles. The test fuels included a CARB phase 2 certification fuel with 11% MTBE content, a CARB phase 3 certification fuel with a 5.7% ethanol content, and E10, E20, E50, and E85 fuels. In most cases, THC and NMHC emissions were lower with the ethanol blends, while the use of E85 resulted in increases of THC and NMHC for the FFV. CO emissions were lower with ethanol blends for all vehicles and significantly decreased for earlier model vehicles. Results for NO x emissions were mixed, with some older vehicles showing increases with increasing ethanol level, while other vehicles showed either no impact or a slight, but not statistically significant, decrease. CO 2 emissions did not show any significant trends. Fuel economy showed decreasing trends with increasing ethanol content in later model vehicles. There was also a consistent trend of increasing acetaldehyde emissions with increasing ethanol level, but other carbonyls did not show strong trends. The use of E85 resulted in significantly higher formaldehyde and acetaldehyde emissions than the specification fuels or other ethanol blends. BTEX and 1,3-butadiene emissions were lower with ethanol blends compared to the CARB 2 fuel, and were almost undetectable from the E85 fuel. The largest contribution to total carbonyls and other toxics was during the cold-start phase of FTP.
Increasing atmospheric burden of ethanol in the United States
Geophysical Research Letters, 2012
The use of ethanol as a transportation fuel in the U.S. increased significantly from 2000-2009, and in 2010 nearly all gasoline contained 10% ethanol. In accordance with this increased use, atmospheric measurements of volatile organic compounds in Los Angeles in 2010 were significantly enriched in ethanol compared to measurements in urban outflow in the Northeast U.S. in 2002 and 2004. Mixing ratios of acetaldehyde, an atmospheric oxidation product of ethanol, decreased between 2002 and 2010 in Los Angeles. Previous work has suggested that large-scale use of ethanol may have detrimental effects on air quality. While we see no evidence for this in the U.S., our study indicates that ethanol has become a ubiquitous compound in urban air and that better measurements are required to monitor its increase and effects.
2006
The Energy Policy Act of 2005 includes a provision designed to double the production and use of ethanol in fuels by 2012, and that beginning in 2013, a minimum of 250 million gallons per year of ethanol be produced from lignocellulosic sources such as corn stover, wheat straw, and switchgrass. This study was conducted to determine the environmental and health consequences of using ethanol as an additive to gasoline. Comparisons are made among conventional gasoline (CG), a blend of 10 percent corn-ethanol and 90 percent CG (E10-corn), and a blend of 10 percent ethanol produced from lignocellulosic biomass (LCB) and 90 CG (E10-LCB).
2009
My enclosed prior technical paper from June 2007 provides a broader and more comprehensive analysis of all the potential adverse impacts of mid-level ethanol fuels when used to operate lawn, garden and forestry products. (See Exhibit B). As explained below, the new DOE report does not address or evaluate most of these outstanding problems or concerns. It is well-established that ethanol fuels generally permeate at significantly higher rates through certain plastics, nylon, and rubber materials used in fuel tanks and system. However, DOE did not conduct any emissions testing pertaining to evaporative emissions. Evaporative emissions (from fuel tanks, fuel lines and engines) in small engines and equipment are now regulated by EPA. (See Exhibit B at p. 14).
Environmental impacts connected with the use of ethanol-gasoline blends
As a summary of work in the project “Influence of bioethanol fuels treatment for operational performance, ecological properties and GHG emissions of spark ignition engines (Biotreth)”, evolving around the effects from bioethanol blending, this paper summarizes the findings from the 3-year long project. These are 1) attributional life cycle assessment (LCA) of the environmental impact connected with the blended fuels, and 2) molecular dynamics simulations of exhaust from the blended fuels. Bioethanol has been increasingly applied as a renewable energy component in combination with gasoline for the reduction of emissions and to reduce the release of climate gases into the atmosphere. Here the environmental and health impacts resulting from introducing bioethanol blended into fossil fuels are assessed. This bio-blended fuel is an alternative to fossil fuels, and their multivariate results are presented with the potential environmental impacts of the production (well-to-tank) of certain multifunctional detergent additive packages (MDAPs) combined with different ethanol-gasoline blends. Moreover the effect of feedstock for ethanol in Switzerland and Poland on end-point modelling results is explored. The resulting combustion products, as a result of adding these new MDAP to the ethanol-gasoline blends, are measured and added to the well-to-wheel LCA focused on GWP100, Cumulative Energy Demand and Eco- -indicator’99. MDAP production eco-environmental impacts are estimated based on their chemical structure. To assess the potentials for new types of emission compounds we have used molecular dynamics simulations. The combination of bioethanol and gasoline introduces two leading toxic components in the urban atmosphere as potentially toxic mixtures: acetaldehyde and poly aromatic hydrocarbons (PAHs) were established. The PAHs are found in combusted gasoline and are virtually absent in emissions of bioethanol. Bioethanol however, contributes with acetaldehyde, which is a potential carcinogen. In this study, we have studied the dynamics of particle formation between acetaldehyde and phenanthrene, which is a PAH found at high concentrations in generic fossil fuel emissions. Our analysis resolves the interaction of these two main emission toxic components at the molecular level in virtual chambers of 300 to 700K, under standard atmospheric conditions and under high pressure and temperature from the engine and exhaust pipe and also reveals their interaction with environmental humidity, modelled as single-point charged water molecules. The results show so far that PAHs and phenanthrene can combine in the water phase and form aqueous nanoparticles, which can be easily absorbed in the lungs through respiration. Water droplets in moisture become potential carriers of PAHs to the exposed subjects by forming non-covalent bonds with acetaldehyde, which in turn binds phenanthrene via its hydrophobic group.
Effects of ethanol (E85) versus gasoline vehicles on cancer and mortality in the United States
Environmental Science & Technology, 2007
Ethanol use in vehicle fuel is increasing worldwide, but the potential cancer risk and ozone-related health consequences of a large-scale conversion from gasoline to ethanol have not been examined. Here, a nested globalthrough-urban air pollution/weather forecast model is combined with high-resolution future emission inventories, population data, and health effects data to examine the effect of converting from gasoline to E85 on cancer, mortality, and hospitalization in the United States as a whole and Los Angeles in particular. Under the base-case emission scenario derived, which accounted for projected improvements in gasoline and E85 vehicle emission controls, it was found that E85 (85% ethanol fuel, 15% gasoline) may increase ozone-related mortality, hospitalization, and asthma by about 9% in Los Angeles and 4% in the United States as a whole relative to 100% gasoline. Ozone increases in Los Angeles and the northeast were partially offset by decreases in the southeast. E85 also increased peroxyacetyl nitrate (PAN) in the U.S. but was estimated to cause little change in cancer risk. Due to its ozone effects, future E85 may be a greater overall public health risk than gasoline. However, because of the uncertainty in future emission regulations, it can be concluded with confidence only that E85 is unlikely to improve air quality over future gasoline vehicles. Unburned ethanol emissions from E85 may result in a global-scale source of acetaldehyde larger than that of direct emissions. *
Journal of the Air & Waste Management Association, 2010
This paper reports on the estimated potential air emissions, as found in air permits and supporting documentation, for seven of the first group of precommercial or "demonstration" cellulosic ethanol refineries (7CEDF) currently operating or planning to operate in the United States in the near future. These seven refineries are designed to produce from 330,000 to 100 million gal of ethanol per year. The overall average estimated air emission rates for criteria, hazardous, and greenhouse gas pollutants at the 7CEDF are shown here in terms of tons per year and pounds per gallon of ethanol produced. Water use rates estimated for the cellulosic ethanol refineries are also noted. The air emissions are then compared with similar estimates from a U.S. cellulosic ethanol pilot plant, a commercial Canadian cellulosic ethanol refinery, four commercial U.S. corn ethanol refineries, and U.S. petroleum refineries producing gasoline. The U.S. Environmental Protection Agency (EPA) air pollution rules that may apply to cellulosic ethanol refineries are also discussed. Using the lowest estimated emission rates from these cellulosic ethanol demonstration facilities to project air emissions, EPA's major source thresholds for criteria and hazardous air pollutants might not be exceeded by cellulosic ethanol refineries that produce as high as 25 million gal per year of ethanol (95 ML). Emissions are expected to decrease at cellulosic ethanol refineries as the process matures and becomes more commercially viable. IMPLICATIONS Development of the next generation of biofuels is already underway with the recent development and operation of approximately 25 cellulosic ethanol demonstration refineries in the United States. These fledgling biofuel refineries, many funded in part by the U.S. Department of Energy, are attempting to show that the production of fuel from nonfood but carbon-neutral sources is economically and technically feasible. The environmental impacts in terms of air and water are being closely watched; this paper shows that low impacts appear to be achievable.