Automotive Fuel Economy How Far Can We Go? (1992) / Chapter Skim
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4 ENVIRONMENTAL ISSUES
4 ENVIRONMENTAL ISSUES
Pages 69-89
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From page 69... ...
This chapter examines briefly the nature of automotive emissions, trends in automotive emissions control and air quality, current and prospective clean air standards, the need to reduce emissions further, and the direct and indirect effects of emissions controls on fuel economy. THE NATURE OF AUTOMOTIVE EMISSIONS Air pollution from motor vehicles arises from evaporative emissions from the fueling systems of volatile organic compounds (VOCs)
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From page 70... ...
Carbon dioxide (CO2) , a greenhouse gas, is a common and necessary by-product of any engine that burns carbon-based fuels, but its potential effect on global climate is a cause for increasing international concern.3 Recent studies have addressed the issue of possible global warming from projected increases in the concentrations of greenhouse gases -- C02, methane, nitrous oxide (N2O)
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From page 71... ...
and other manufacturers are expected to adopt similar schedules.6 AUTOMOTIVE EMISSIONS CONTROL AND AIR QUALITY: A BRIEF HISTORY Concern with air quality, including ground-level ozone, increased during the 1960s and led to federal and state motor vehicle standards for emissions of HCs, CO, and NOX. Enabling legislation was passed in California in 1965 and at the federal level in the Air Quality Act of 1967 and the Clean Air Act amendments of 1970, 1971, and 1977 (P.~.
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From page 72... ...
STANDARDS IN THE 1990 CLEAN AIR ACT AMENDMENTS Federal Standards The Clean Air Act amendments of 1990 established stringent tailpipe emissions standards for nonmethane hydrocarbons (NMHC) ,9 CO, NOX, and particulates for passenger cars and light trucks of 6,000 pounds gross vehicle weight (GVW)
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From page 73... ...
(see Table 4-2~. A gradual phasein of these increasingly "clean" automobiles is planned as manufacturers produce the TABLE 4-1 Passenger-Car Emissions Standards (grams per miles, Clean Air Act Amendments of 1990 Gasoline Engines Standard NMHC NOx Diesel Engines PM NOx Current (1991)
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From page 74... ...
To meet Californ~a's goal to reduce nonmethane organic gases (NMOG) , the manufacturers will have to achieve a decreasing fleet-average standard for these emissions using a combination of the vehicles identified above.~° Under the provisions of the Clean Air Act amendments, the 31 other nonattairunent states may adopt Californ~a's standards, and a number of states intend to do so.l1 The states that have taken action or are considering it represent about half of the new-car market in the United States.
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From page 75... ...
These changes watt add cost and may impose increases in vehicle weight. In sum, control of NOX and HC emission to meet Tier IT and California LEV and ULEV levels presents many substantial challenges to automotive manufacturers.
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From page 76... ...
45Emissions-control equipment on 1991 models accounts for about 25 pounds in cars and 35 pounds in light trucks (Kelly Brown, Ford Motor Company, personal communication, December 1991~. Fin presentations to the committee, Honda estimated that Tier I standards will reduce economy by 1.5 percent and increase vehicle weight by 45 to 66 pounds and that California's standards will reduce fuel economy by an additional 1.5 percent.
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From page 77... ...
° Some improvement in NOX control may be achieved in heavier vehicles by using oversized engines with internal exhaust-gas recycling (EGR) as a means of reducing the peak cylinder temperature.
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From page 78... ...
In new large plants, such as utility boilers, up to 90 percent reduction of the NOX emissions is possible using existing technology, and somewhat lower Percentage reductions are possible in retrofitted applications and in smaller facilities.2 Existing standards, however, do not appear to require such significant reductions from stationary sources. In light of the difficulty of achieving further stringent NOX reductions in automobiles, perhaps reduction from stationary 22Use of lean systems win also result in the oxidation of NO to NO2 in the exhaust system.
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From page 79... ...
Before Tier T! standards are adopted nationwide, a detailed assessment should be made to determine whether it is more practical on a region-by-region basis to achieve higher levels of NOx control from stationary sources than to achieve 95 percent control for mobile sources of NOx.
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From page 80... ...
In anticipation of these regulations, the automotive manufacturers and the oil industry formed a cooperative program, the Auto/Oil Air Quality Improvement Research Program, to assess the effects of changes in gasoline composition on emissions. Results thus far indicate that HC emissions can be reduced in MY 1983-1985 and MY 1989 vehicles by 5 to 9 percent by including 15 percent of methyl tertiary butyl ether (MTBE, an 27Control is achieved by use of a special nozzle on the gasoline pump that allows the capture of HCs that would otherwise be expelled during refueling.
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From page 81... ...
Also, one of the automotive manufacturers told the committee that, individually, these latter changes would lower fuel economy by up to 2.8 percent, largely because of the decrease in volumetric heat content of the fuel. These reductions are not additive, and estimates of the combined effects of changes in fuel composition that might be made are not yet available.
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From page 82... ...
Clearly, opportunities to control these stationary sources should be carefully considered as an offset to more stringent HC standards for automobiles. Impact of Emissions Standards on Light Trucks In the past, emission standards have affected light trucks in much the same way as they have affected cars, and this trend is expected to continue.
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From page 83... ...
However, in general the emissions standards will increase the percentage of trucks that use gasoline engines because of the NOX and particulate emissions characteristics of diesel engines.33 Manufacturers told the committee that a 25 to 50 percent reduction in NOX from the current ~ 8pm requirement might be achieved in diesels using combustion modification. They thought, however, that higher levels of control would require use of methanol fuel instead of diesel and even then were not optimistic about meeting the 0.2 8pm Tier IT standard.
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From page 84... ...
Fuel economy improvements reduce total HC emissions, considering emissions from the production, transportation, refining, and marketing of fuel (DeLuchi et al., 1991~. But greenhouse gas emissions from the production of substitute materials, such as aluminum, could substantially offset decreases of those emissions achieved through improved fuel economy, although this would strongly depend on the energy source used for the production of the materials.
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From page 85... ...
sales of cars and light trucks. In view of the difficulty of meeting these NOx standards, other approaches, such as increasing control of NOx from stationary sources, should be considered.
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From page 86... ...
1990. Clean Air Act amendments.
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From page 87... ...
1991. Motor vehicle fuel economy, the forgotten HC control strategy?
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From page 88... ...
1990. The NEW Clean Air Act, A Guide to the Clean Air Program as Amended in 1990.
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From page 89... ...
1991. Implementation Strategy for the Clean Air Act Amendments of 1990.
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