Air Quality Management in the United States (2004) / Chapter Skim
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4 Implementing Emission Controls on Mobile Sources
4 Implementing Emission Controls on Mobile Sources
Pages 133-173
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From page 133... ...
. The persistence of the need to address mobile emissions is not, however, an indication that the largely technological controls applied to mobile sources have been ineffective; indeed, emission rates from individual vehicles have decreased substantially since enactment of the CAA.
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From page 134... ...
Motorcycles New standards to reduce emissions by 80% (based on California) (proposed 2002; to take effect 20062010)
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From page 135... ...
Onroad vehicles may be fueled with gasoline, diesel fuel, or alternative fuels, such as alcohol or natural gas. Nonroad sources refer to gasoline- and diesel-powered equipment and vehicles operated off-road, ranging in size from small engines used in lawn and garden equipment to locomotive engines and aircraft.
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From page 136... ...
. 2Although the first federal controls on mobile sources began with regulations on passenger cars for the 1968 model year, California began mandating emission controls on passenger cars in the early 1960s.
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From page 137... ...
. The CAA Amendments of 1977, extended the emission standards deadlines for carbon monoxide and hydrogen until 1983 and 1980, respectively.
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From page 138... ...
138 AIR QUALITY MANAGEMENT IN THE UNITED STATES A 10 California Federal (g/mi) 1 Standard 0.1 Emission 0.01 1960 1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 Model Year B 90 California 80 Federal 70 60 (g/mi)
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From page 139... ...
These figures are for exhaust emissions only. For the uncontrolled vehicles in 1960, there were also VOC emissions from crankcase blowby, which have been completely eliminated, and evaporative VOC emissions, which have also had a high degree of control.
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From page 140... ...
. That was due to challenges in reducing emissions from all sources, but among mobile sources, there was continued growth in VMT and new scientific and technological information that some emissions, especially evaporative emis BOX 4-2 Technology Innovation and Emission Controls The development and widespread application of pollution-control technologies have permitted reductions in criteria pollutant emissions even while vehicle miles traveled has continually increased.
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From page 141... ...
, the 1990 requirements tightened significantly the controls on evaporative emissions, especially during refueling.6 Also, the 1990 CAA Amendments authorized the EPA administrator to establish more stringent Tier II controls in 2004 if they were judged to be needed, technically feasible, and cost-effective (Howitt and Altshuler 1999)
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From page 142... ...
9The basis of the injunction was not directly related to the emission standards but rather to language in the ZEV requirement that the court found was a form of "fuel economy" mandate that federal law reserves for the federal government alone (Central Valley ChryslerPlymouth, et al. v California Air Resources Board, et al.
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From page 143... ...
The regulations, to be phased in between model years 2004 and 2010, will reduce PM and NOx emissions by at least 90% from current standards. To meet these more stringent standards for diesel engines, the sulfur content of diesel fuel will be reduced by 97% from its current level of 500 parts per million (ppm)
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From page 144... ...
The 1990 CAA Amendments directed EPA to prepare a study of the scope and sources of nonroad emissions and to regulate them if they were found to make a substantial contribution to O3 or CO nonattainment. The EPA report did not make a formal determination of a significant effect, but it contained an inventory of emissions from nonroad sources and concluded, "because nonroad sources are among the few remaining uncontrolled sources of pollution, their emissions appear large in comparison to the emissions from sources that are already subject to substantial emissioncontrol requirements" (EPA 1991)
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From page 145... ...
Implementation of Emission Standards for New Mobile Sources Motor-vehicle emission standards are implemented through a certification procedure in which manufacturers provide EPA or the California Air Resources Board (CARB) with prototype data showing that the vehicles
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From page 146... ...
Congress sought to remedy the off-cycle emissions problem in the 1990 CAA Amendments by requiring EPA to control off-cycle emissions. To do so, EPA developed the supplemental federal test procedure (SFTP)
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From page 147... ...
The test cycle is based on engine torque and rotational speed. The emission standards are written in terms of the emission rate per unit power 11Language was incorporated into the Clean Air Act Amendments that directed EPA to achieve reductions in evaporative emissions during certain operating conditions.
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From page 148... ...
In implementing the 1977 CAA Amendments, EPA determined that many states needed annual or biennial I/M programs to ensure that the tailpipe emission-control devices it had mandated were in place and operating properly. In some cases, motorists appeared to intentionally disable these devices or damage them by using leaded gasoline (Howitt and Altshuler 1999)
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From page 149... ...
are becoming increasingly sophisticated and could provide accurate measurements of in-use vehicle emissions under actual driving conditions. Finally, on-board diagnostic (OBD)
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From page 150... ...
First, further controlled testing of the technology for quality assurance and quality control, as well as development of technologies for other mobile-source pollutants, such as PM, will be important to its expanded use. In addition, because remote sensing does not monitor a vehicle over its full range of operating conditions and is not yet able to monitor evaporative emissions, it is probably best used at this time as an adjunct to annual or biennial inspections and on-board diagnostics.
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From page 151... ...
However, diesel trucks built before 1977 emit twice as much NOx as those built after 1996, and those built between 1977 and 1980 emit 50% more than those built after 1996. NOx emissions from trucks built before 1981 represent about 5% of the total from trucks.
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From page 152... ...
. Abbreviations: GVWR, gross-vehicle-weight rating; VMT, vehicle miles traveled; g, gram.
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From page 153... ...
. Abbreviations: GVWR, gross-vehicle-weight rating; VMT, vehicle miles traveled; g, gram.
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From page 154... ...
In addition to these regulations, there have been various proposals and requirements in the CAA, state rules, and national energy legislation for the promotion of alternative fuels to reduce the emissions from motor vehicles. Fuels proposed for this purpose include methanol, ethanol, natural gas, liquefied petroleum gas (LPG)
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From page 155... ...
The requirements in the 1990 CAA Amendments to control evaporative emissions from LDVs and implement the reformulated gasoline program were in large part an effort to reverse the increase in evaporative VOCs. The 1990 Amendments also required a substantial increase in oxygen content, resulting in a later unintended consequence -- groundwater contamination from the high use of MTBE.
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From page 156... ...
1988 California Clean Air Act 1989 Summer volatility (Reid vapor pressure) regulations, Phase 1 1990 Clean Air Act Amendments 1992 California reformulated gasoline, Phase I 1992 Summer volatility regulations, Phase 2 1992 Winter Oxygenated Gasoline required 2.7% minimum oxygen content in about 40 CO nonattainment areas 1995 Federal reformulated gasoline, Phase I 1996 Completion of phase-out of lead in gasoline 1996 California reformulated gasoline, Phase II 2000 Federal reformulated gasoline, Phase II 2002 California Phase III gasoline effective December 31, 2002 2003 California regulations for reformulated diesel fuel effective 2004 Phase-in of federal low-sulfur gasoline requirements begins 2006 Phase-in of federal low-sulfur diesel requirements begins levels lead g/dL)
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From page 157... ...
In the years preceding adoption of the 1990 CAA Amendments, increased action by states was focused on the need to regulate fuels in addition to motor vehicles. In 1988, Colorado pioneered oxygenate requirements for gasoline -- specifying a minimum oxygen content of 1.5% by weight during the winter -- to reduce CO emissions.
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From page 158... ...
The 1990 CAA Amendments also established a nonattainment area fleet program and a California pilot program to encourage the development and use of clean-fueled vehicles. As described in Chapter 2, the RFG program was also intended to reduce emissions of benzene, one of the principal mobile-source air toxics.
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From page 159... ...
SOURCE: NRC 1999b. TABLE 4-5 Part 2: Future Reformulated Gasoline Program Federal RFG Program, Phase II (2000 )
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From page 160... ...
To determine whether a specific fuel complies with the performance standards, EPA developed two regression models from laboratory tests of vehicles operated on fuels with a wide range of compositions and properties. These models, known as the simple and complex models, estimate exhaust and evaporative emissions based on fuel properties such as RVP, oxygen content, sulfur content, and the fuel's distillation curve.
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From page 161... ...
New vehicles with properly functioning closedloop control systems show relatively little benefit.16 Thus, the effectiveness of the oxyfuels program has diminished as the vehicle fleet has turned over. The CAA Amendments of 1990 do not have a sunset provision for the oxygenated fuels requirement, but in effect this requirement has been diminishing as a large portion of locales with high ambient CO concentrations have attained or are close to attainment of the CO NAAQS.
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From page 162... ...
Regulation of Motorists' Vehicle Use Under the CAA Amendments of 1970, EPA required the states to develop transportation control plans (TCPs) for their air pollution control areas (normally, metropolitan regions)
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From page 163... ...
. The 1977 CAA Amendments did not mandate restrictions on personal travel, although they permitted states to adopt restrictions if they wished.
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From page 164... ...
Before the 1990 CAA Amendments, neither federal law nor the practices of metropolitan transportation planning linked air quality management with urban transportation investment policy. The National Environmental Policy Act (NEPA)
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From page 165... ...
. The Conformity Regulations The CAA Amendments of 1990 and the Intermodal Surface Transportation Efficiency Act (ISTEA)
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From page 166... ...
Before the conformity regulations of the 1990 CAA Amendments, transportation planning and air quality regulation were effectively separate spheres of government activity, even within a given state. Conformity appears to have fostered greater interaction; as a result, it is likely that transportation and environmental agencies have gained more knowledge about and a greater appreciation for one another's missions, responsibilities, and procedures.
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From page 167... ...
Mobile-source emission-control programs have also experienced and continue to experience challenges, including the persistence of high-emitting gasoline vehicles and older diesel vehicles, the relative lack of regulation of nonroad engine emissions, the contributions of mobile sources to HAP emissions (see discussion of HAPs in Chapter 5) , the use of fuel policy to pursue other non-air-quality-related interests (for example, farm policy and reducing dependence on foreign oil)
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From page 168... ...
. High-Emitting Gasoline Vehicles The emission-control program for mobile sources has been very successful in terms of its ability to reduce emissions from individual LDVs, operated in normal modes.
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From page 169... ...
Reducing Emissions from Older and Nonroad Diesel Engines Although there has been and probably will be substantial progress in reducing the emissions from new on-road diesel vehicles, three substantial challenges remain. First, the long life of diesel vehicles and the pattern in which older vehicles are used for shorter-haul routes in urban centers result in a large and continuing source of PM and NOx diesel emissions in urban settings with dense populations.
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From page 170... ...
The 1970 and 1977 CAA Amendments were ineffective in ensuring consistency between state transportation investments and air quality improvement commitments. The 1990 CAA Amendments embodied a more realistic appreciation of how transportation decisions can affect air quality planning and backed the requirement for conformity with the tangible threat of federal fiscal penalties for failure to comply.
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From page 171... ...
Moreover, the planning horizons for air quality regulation and transportation planning may mesh poorly. Under current requirements, transportation plans are required to have a 20-year time horizon, and conformity is done on that basis.
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From page 172... ...
If transportation emission forecasts are updated while other sectors' are not, the validity and perceived fairness of the results can be questioned and stakeholder support for pollution reductions can be undermined. Some proponents of conformity hoped that linking transportation and land use would encourage broader acceptance of land-use regulations to reduce emissions from mobile sources.
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From page 173... ...
· The inclusion of content-specific requirements in the fuel provisions of the 1990 CAA Amendments (for example, oxygen in the RFG program) can limit flexibility to meet standards in the most cost-effective way for areas required to implement the program.
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