Mobile sources

The term inversion in this context refers to the atmospheric condition whereby there is an increase in temperature with altitude, in contrast with the norm, where there would be a decrease in temperature with altitude. Such an inversion can lead to pollution and smog being trapped close to the ground. It is believed that the exhaust emissions from automobiles contribute strongly to the genesis of this type of inversion. 

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Compilation of yiirPollution Emission Factors, Pub. No. AP-42, 5th ed., U.S. Environmental Protection Agency, Research Triangle Park, N.C., 1989. Compilation of A.ir Pollution Emission Factors, Vol 2. Mobile Sources, Pub. No. AP-42, 5th ed., U.S. Environmental Protection Agency, Research Triangle Park, N.C., 1989. 

Office of Mobile Sources, Analysis of the Economic and Environmental Effects of Methanol as an Automotive Euel, U.S. Environmental Protection Agency, Ann Arbor, Mich., Sept. 1989. 

Mobile Source Division, AlcoholEueled Vehicle Elect Test Program 9th Interim Report, Pub. ARB /MS-89-09, California Air Resources Board, El Monte, Calif., Nov. 1989. 

American Petroleum Institute, Task Force EF-18 of the Committee on Mobile Source Emissions, Alcohols—A Technical Assessment of Their Application as Fuels, Publication Mo. 4261, API, New York, July 1976. 

If the source fingerprints, for each of n sources are known and the number of sources is less than or equal to the number of measured species (n < m), an estimate for the solution to the system of equations (3) can be obtained. If m > n, then the set of equations is overdetermined, and least-squares or linear programming techniques are used to solve for L. This is the basis of the chemical mass balance (CMB) method (20,21). If each source emits a particular species unique to it, then a very simple tracer technique can be used (5). Examples of commonly used tracers are lead and bromine from mobile sources, nickel from fuel oil, and sodium from sea salt. The condition that each source have a unique tracer species is not often met in practice. 

American Gas Association (AGA), "Projected Natural Gas Demand Prom Vehicles Under the Mobile Sources Provisions of the Clean Ah Act Ammendments," AGA Energy Analysis EA 1991—1991, Chicago, 1991. 

A mobile source of air pollution can be defined as one capable of moving from one place to another under its own power. According to this definition, an automobile is a mobile source and a portable asphalt batching plant is not. Generally, mobile sources imply transportation, but sources such as construction equipment, gasoUne-powered lawn mowers, and gasoline-powered tools are included in this category. 

Mobile sources therefore consist of many different types of vehicles, powered by engines using different cycles, fueled by a variety of products, and emitting varying amounts of both simple and complex pollutants. Table 6-4 includes the more common mobile sources. 

National Research Council, "Odors from Stationary and Mobile Sources." National Academy of Sciences, Washington, DC, 1979. 

The EPA has summarized the provisions related to mobile sources (4) as follows ... 

Within 6 months after enactment of the Qean Air Act Amendments of 1990, and at least every 3 years thereafter, the Administrator shall review and, if necessary, revise, the methods ( emission factors ) used for purposes of this Act to estimate the quantity of emissions of carbon monoxide, volatile organic compounds, and oxides of nitrogen from sources of such air pollutants (including area sources and mobile sources). In addition, the Administrator shall permit any person to demonstrate improved emissions estimating techniques, and following approval of such techniques, the Administrator shall authorise the use of such techniques. Any such technique may be approved only after appropriate public participation. Until the Administrator has completed the revision required by this section, nothing in this section shall be construed to affect the validity of emission factors established by the Administrator before the date of the enactment of the Clean Air Act Amendments of 1990. 

Mobile sources include railroad locomotives, marine vessels, aircraft, and automotive vehicles. Over the past 100 years, we have gained much experience in regulating smoke and odor emission from locomotives and marine craft. Methods of combustion equipment improvement, firefighter training, and smoke inspection for these purposes are well documented. This type of control is best at the local level. 

Because mobile sources of air pollution are capable of moving from one local jurisdiction to another, they are usually regulated by the national government. In the United States, state or local agencies can have more restrictive standards, if they choose. Through 1990, only the state of California had established standards more restrictive than the U.S. federal standards, and these only for gasoline-powered automobiles. 

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. 

The atmosphere of the world cannot continue to accept greater and greater amounts of emissions from mobile sources as our transportation systems expand. The present emissions from all transportation sources in the United States exceed 50 biUion kg of carbon monoxide per year, 20 billion kg per year of unbumed hydrocarbons, and 20 billion kg of oxides of nitrogen. If presently used power sources cannot be modified to bring their emissions to acceptable levels, we must develop alternative power sources or alternative transportation systems. All alternatives should be considered simultaneously to achieve the desired result, an acceptable transportation system with a minimum of air pollution. 

The second point of view is that the engineering design of control systems for stationary and mobile sources requires a command of the principles of... 

In the United States, in particular, recent legislation has mandated sweeping improvements to urban air quality by limiting mobile source emissions and by promoting cleaner fuels. The new laws require commercial and government fleets to purchase a substantial number of vehicles powered by an alternative fuel, such as natural gas, propane, electricity, methanol or ethanol. However, natural gas is usually preferred because of its lower cost and lower emissions compared with the other available alternative gas or liquid fuels. Even when compared with electricity, it has been shown that the full fuel cycle emissions, including those from production, conversion, and transportation of the fuel, are lower for an NGV [2]. Natural gas vehicles offer other advantages as well. Where natural gas is abundantly available as a domestic resource, increased use... 

The United States generates about 20 million metric tons of nitrogen oxides per year, about 40% of which is emitted from mobile sources. Of the 11 million to 12 million metric tons of nitrogen oxides that originate from stationary sources, about 30% is the result of fuel combustion in large industrial furnaces and 70% is from electric utility furnaces. 

Mobile Sources moving objects that release regulated air pollutants, e.g., cars, trucks, buses, planes, trains, motorcycles, and gas-powered lawn mowers. See also source stationary source. 

Source any place or object from which air pollutants are released. Sources that are fixed in space are stationary sources sources that move are mobile sources. See also major source. 

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