Carbon monoxide vehicle emissions

Human-made sources cover a wide spectrum of chemical and physical activities and are the major contributors to urban air pollution. Air pollutants in the United States pour out from over 10 million vehicles, the refuse of over 250 million people, the generation of billions of kilowatts of electricity, and the production of innumerable products demanded by eveiyday living. Hundreds of millions of tons of air pollutants are generated annu ly in the United States alone. The five main classes of pollutants are particulates, sulfur dioxide, nitrogen oxides, volatile organic compounds, and carbon monoxide. Total emissions in the United States are summarized by source categoiy for the year 1993 in Table 25-10. 

Back where it all began, the increasing vehicle population and the increasing frequency of red-eye days led the California Legislature in 1959 to require the State Department of Public Health to develop and publish standards for the quality of air and for vehicle exhaust emissions before February 1, 1960 (14). These standards, which were adopted on December 4, 1959, were based on the judgement that in order to achieve desirable air quality standards, 80% reduction of hydrocarbon (HC) and 60% reduction of carbon monoxide (CO) emissions were needed. In terms of the test cycle which was also established, the standards were 275 ppm (volume) of hydrocarbons as hexane (or 0.165% as C] ) and 1.5% (volume) of CO. 

However, such a level can still be considered too high for vehicles having 3-way catalytic converters. In fact, results observed in the United States (Benson et al., 1991) and given in Figure 5.20 show that exhaust pollutant emissions, carbon monoxide, hydrocarbons and nitrogen oxides, increase from 10 to 15% when the sulfur level passes from 50 ppm to about 450 ppm. This is explained by an inhibiting action of sulfur on the catalyst though... 

Vehicle Emissions. Gasohol has some automotive exhaust emissions benefits because adding oxygen to a fuel leans out the fuel mixture, producing less carbon monoxide [630-08-2] (CO). This is tme both for carbureted vehicles and for those having electronic fuel injection. 

Carbon monoxide was discovered in 1776 by heating a mixture of charcoal and 2inc oxide. It provided a source of heat to industry and homes as a component of town gas and was used as a primary raw material in German synthetic fuel manufacture during World War II its compounds with transition metals have been studied extensively (see Carbonyls). Most recently, carbon monoxide emission from vehicle exhausts has been recognized as a primary source of air pollution (qv). 

The Clean Air Act of 1990 establishes tighter pollution standards for emissions from automobiles and trucks. These standards will reduce tailpipe emissions of hydrocarbons, carbon monoxide, and nitrogen oxides on a phased-in basis beginning in model year 1994. Automobile manufacturers will also be required to reduce vehicle emissions resulting from the evaporation of gasoline during refueling. 

Public concerns about air quality led to the passage of the Clean Air Act in 1970 to amendments to that act in 1977 and 1990. The 1990 amendments contained seven separate titles covering different regula-toiy programs and include requirements to install more advanced pollution control equipment and make other changes in industrial operations to reduce emissions of air pollutants. The 1990 amendments address sulfur dioxide emissions and acid rain deposition, nitrous oxide emissions, ground-level ozone, carbon monoxide emissions, particulate emissions, tail pipe emissions, evaporative emissions, reformulated gasoline, clean-fueled vehicles and fleets, hazardous air pollutants, solid waste incineration, and accidental chemical releases. 

Transportation accounts for about one-fourth of the primary energy consumption in the United States. And unlike other sectors of the economy that can easily switch to cleaner natural gas or electricity, automobiles, trucks, nonroad vehicles, and buses are powered by internal-combustion engines burning petroleum products that produce carbon dioxide, carbon monoxide, nitrogen oxides, and hydrocarbons. Efforts are under way to accelerate the introduction of electric, fuel-cell, and hybrid (electric and fuel) vehicles to replace sonic of these vehicles in both the retail marketplace and in commercial, government, public transit, and private fleets. These vehicles dramatically reduce harmful pollutants and reduce carbon dioxide emissions by as much as 50 percent or more compared to gasoline-powered vehicles. 

Almost all the major car, bus, and truck manufacturers have developed compressed natural gas engines and vehicles. These manufacturers have been able to offer better performance (due to higher octane) and far lower emissions of nitrogen oxides, carbon monoxide, particulate matter, and carbon dioxide to the atmosphere. In 1998, Honda introduced the cleanest internal combustion engine vehicle ever commercially produced the natural gas Civic GX with emissions at one-tenth the state of California s Ultra Low Emission Vehicle standard. Primarily due to the high octane of natural gas, Honda achieved these results without sacrificing performance. 

Air pollution is principally a problem in urban and heavily industrialized areas, where the flow of clean air from surrounding areas is insufficient to disperse the accumulation. Motor vehicles account for more than 50% of the man-made emissions of carbon monoxide, hydrocarbons, and nitrogen oxides (4). More than half of the U.S. annual trillion vehicle miles are driven in urban areas (5). Nature produces much more pollutants than all man-made sources, but natural emissions are widely dispersed and do not contribute heavily to urban pollution problems (6, 7). 

In Mexico City, several air quality parameters are measured continuously by an Automated Monitoring Network operated by the Under Secretariat of Ecology. Carbon monoxide, particulate matter, sulfur dioxide, nitrogen oxide, and ozone are the contaminants exceeding Air Quality Standards. Emissions produced by 2.7 million vehicles and 35,000 commercial and industrial outfits are not easily dispersed in a Valley located at 2240 m and surrounded by two mountain chains which hinder air circulation. An Integral Program, recently established to alleviate pollution, is briefly described. 

Carbon monoxide (CO) Is one of the most widely distributed air pollutants. It Is formed by natural biological and oxidation processes, the Incomplete combustion of carbon-containing fuels and various Industrial processes. However, the largest Individual source of man-made emissions Is motor vehicle exhausts which account for virtually all CO emitted In some urban environments. It has been estimated that global man-made emissions range from 300-1600 million tons per year, which Is approximately 60% of the total global CO emissions (22-23). 

In the USA, the Clean Air Act of 1970 established air-quality standards for six major pollutants particulate matter, sulfur oxides, carbon monoxide, nitrogen oxides, hydrocarbons, and photochemical oxidants. It also set standards for automobile emissions - the major source of carbon monoxide, hydrocarbons, and nitrogen oxides. An overview of the major standards is given in Tab. 10.2. The levels of, for example, the European Union (1996) are easily achieved with the present catalysts. The more challenging standards, up to those for the ultralow emission vehicle, are within reach, but zero-emission will probably only be attainable for a hydrogen-powered vehicle. 

Iceland may start with methanol powered PEM vehicles and vessels. The University of Iceland is involved in research on the production of methanol (CH3OH) from hydrogen combined with carbon monoxide (CO) or C02 from the exhaust of aluminum and ferrosilicon smelters. This would capture hundreds of thousands of tons of CO and C02 released from these smelters. If this is combined with hydrogen generated from electrolysis using renewable power, Iceland could cut its greenhouse gas emissions in half. 

Data from the EEA (2006c) reveal that air emissions from transport follow a slightly less expressed, but well comparable trend to entire emissions between 1990 and 2004. Table 19.2 shows the share for the transport sector of certain pollutants in the EU 40% to 50% of NO, and carbon monoxide (CO), 25% of non-methane volatile organic compounds (NMVOC) and just 1% of sulphur oxides (SO,). In developing countries, and here in particular in the big megacities, the share for transport of SO, heavy metal and particulate emissions (not listed here) will -because of the old vehicle fleets - be much higher. 

---