Vehicle emission standards

In the late 1980s attempts were made in California to shift fuel use to methanol in order to capture the air quaHty benefits of the reduced photochemical reactivity of the emissions from methanol-fueled vehicles. Proposed legislation would mandate that some fraction of the sales of each vehicle manufacturer be capable of using methanol, and that fuel suppHers ensure that methanol was used in these vehicles. The legislation became a study of the California Advisory Board on Air QuaHty and Fuels. The report of the study recommended a broader approach to fuel quaHty and fuel choice that would define environmental objectives and allow the marketplace to determine which vehicle and fuel technologies were adequate to meet environmental objectives at lowest cost and maximum value to consumers. The report directed the California ARB to develop a regulatory approach that would preserve environmental objectives by using emissions standards that reflected the best potential of the cleanest fuels. 

Table 8. California Light-Duty Vehicle Exhaust Emission Standards...

The future use of lead may be decided by the resolution of an environmental paradox. Some markets for lead are being phased out because of environmental concerns, eg, the use of tetraethyllead as a gasoline additive. However, a 1990 State of California law and similar laws in nine eastern U.S. states require that 2% of new cars meet 2ero-emission standards in 1998. By 2003 this requirement rises to 10% of new vehicles. Zero emission vehicles are generally accepted to mean electric, ie, battery powered cars, and there is considerable research effort to bring suitable electric vehicles to market by 1998. 

To add surface area, the supports are uniformly coated with a slurry of gamma-alumina and recalcined under moderate conditions. The wash coat acts to accept the active metals, typically low levels of platinum and palladium, in a conventional impregnation process. In the United States in passenger car apphcations the spherical catalyst is used almost exclusively, and methods have been developed to replace the catalyst without removing the converter shell when vehicle inspection reveals that emission standards are not met. 

In the United States, federal regulations require automobile manufacturers to certify that vehicles are ia compliance with exhaust emission standards when tested under specific test procedures. 

Test Procedure. To comply with emission standards, representative vehicles must be mn for 80,000 km (Appendix IV of the Eederal Test Procedure (ETP)) (3). The first 6,400 km are considered a break-in portion. Exhaust emissions are measured each 8,000 km between approximately 6,400 and 80,000 km of accumulation and a deterioration factor (DE) of emissions is calculated. A DE of 1.15 for HC indicates that HC emissions increased by 15% between 6,400 and 80,000 km, and were within the 80,000 km standard. This DE is appHed to the 6,400 km emission test data points for all other model variations of the family of vehicles represented by the 80,000 km durabiUty car. 

Gasoline-powered motor vehicles outnumber all other mobile sources combined in the number of vehicles, the amount of energy consumed, and the mass of air pollutants emitted. It is not surprising that they have received the greatest share of attention regarding emission standards and air pollution control systems. Table 25-2 shows the U.S. federal emission control requirements for gasoline-powered passenger vehicles. 

Effective with the 1982 model year, particulate matter from diesel vehicles was regulated by the U.S. Environmental Protection Agency for the first time, at a level of 0.37 gm km . Diesel vehicles were allowed to meet an NO level of 0.93 gm km under an Environmental Protection Agency waiver. These standards were met by a combination of control systems, primarily exhaust gas recirculation and improvements in the combustion process. For the 1985 model year, the standards decreased to 0.12 gm of particulate matter per kilometer and 0.62 gm of NO per kilometer. This required the use of much more extensive control systems (1). The Clean Air Act Amendments of 1990 (2) have kept the emission standards at the 1985 model level with one exception diesel-fueled heavy trucks shall be required to meet an NO standard of 4.0 gm per brake horsepower hour. 

State of California Air Resource Board, California Fuel Evaporative Emissions Standard and Test Procedure for 1970 Model Light Duty Vehicles, April 16, 1968. 

Besides cleaner fuels, vehicle makers have developed many emission-reducing technologies—both in cleaner combustion and in catalytic converter technologies—to comply with ever stricter tailpipe emission standards. The U.S. EPA stringent standards proposed in 1999 for model year 2004 vehicles will result in new vehicles emitting less than 1 percent of the VOC and NO, emissions of their 1960s counterparts. 

In 1999, the EPA proposed stringent standards applicable to model year 2004 vehicles. Thus, the EPA continues to implement technology-forcing regulations, in which EPA tasks manufacturers with an emissions standard, and industry must develop... 

New vehicle emissions standards have served as the primary means for reducing vehicle emissions over... 

U.S. Environmental Protection Agency. (2000). Control of Air Pollution from New Motor Vehicles Tier 2 Motor Vehicle Emissions Standards and Gasoline Sulfur Control Requirements. Federal Register 65 6698-6870. 

Air quality suffers from this increasing congestion as well. Motor vehicles create the majority of air quality problems in urban areas, so for cities to comply with stringent ambient air quality standards, they will have to reduce motor vehicle emissions. Trucking accounts for only 4 percent of the U.S. motor vehicle fleet, yet can easily be responsible for 30 to 40 percent of the air quality problems because, in comparison to automobiles, the fleet is far older, is driven far more miles each year, and the emissions per vehicle are far greater. 

Serious research in catalytic reduction of automotive exhaust was begun in 1949 by Eugene Houdry, who developed mufflers for fork lift trucks used in confined spaces such as mines and warehouses (18). One of the supports used was the monolith—porcelain rods covered with films of alumina, on which platinum was deposited. California enacted laws in 1959 and 1960 on air quality and motor vehicle emission standards, which would be operative when at least two devices were developed that could meet the requirements. This gave the impetus for a greater effort in automotive catalysis research (19). Catalyst developments and fleet tests involved the partnership of catalyst manufacturers and muffler manufacturers. Three of these teams were certified by the California Motor Vehicle Pollution Control Board in 1964-65 American Cyanamid and Walker, W. R. Grace and Norris-Thermador, and Universal Oil Products and Arvin. At the same time, Detroit announced that engine modifications by lean carburation and secondary air injection enabled them to meet the California standard without the use of catalysts. This then delayed the use of catalysts in automobiles. 

The latest revision of Emission Standards for New Vehicles was issued in September 1988. A summary of past and present emission standards is given in Table III. 

The Emission Standard for New Diesel Vehicles, issued in December 1988, established a maximum of 50 Hartridge Opacity Units. The Ecological Technical Standard of June, 1988, enforced the maximum allowable emissions for circulating cars (Table IV). The Diesel Regulation... 

In the USA, three-way catalysts have to maintain high activity and meet the emission standards of Tab. 10.2 after 50,000 miles or five years. Because catalysts deactivate with use, fresh catalysts are designed such that they perform well below the emission standards. The extent to which a three-way catalyst deactivates depends on many factors. The wide range of vehicle operating conditions due to differences in style of driving is important. 

In the Asian-Pacific area, only Japan has developed its own vehicle emission standard. Other countries have adopted the US system (Taiwan) or the European standards to different degrees (most other countries). But it should not be forgotten that the share of new cars applying to these standards in developing countries is comparatively low. 

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