The amount of pollution created by electric vehicles depends mostly on the source of the electricity used to charge them. This makes it impossible to determine if electric vehicles pollute less than internal combustion engine vehicles without considering where they are to be deployed and by what sources of electricity they are to be powered. An electric vehicle that is charged with energy from a clean source, like hydroelectric power, will produce very little pollution, while one charged with energy from an unclean source, like coal or oil, may produce more pollution than an internal combustion engine vehicle. The sources of energy for most regions fall somewhere between these two extremes. The use of electric vehicles will allow new possibilities in pollution control and management that may outweigh some of their potentia.l failings. While not ready to be used everywhere, electric vehicles have the potential to pollute much less than internal combustion engine vehicles.
Internal combustion engine vehicles are responsible for the vast majority of pollutants that plague urban areas today. Studies of the sources of air pollution have shown that transportation accounts for the majority of nitrogen oxide (54%) and carbon monoxide (89%) emissions in the United States . Furthermore, internal combustion engines are also believed to be one of the largest single sources of carbon dioxide (28%) emissions . [The next sentence undercuts main point of introduction by bringing up a new topic.] Internal combustion engine vehicles also generate other types of pollution, including sulfur oxides and hydrocarbons, however, the amounts generated by transportation are small compared to other activities.
These emissions are directly responsible for many of the air quality problems faced in major urban areas. For example, carbon monoxide readily bonds with hemoglobin in blood, taking the place that would normally be occupied by oxygen molecules. Exposure to high concentrations of carbon monoxide can cause death, essentially suffocating a person as their cells are deprived of oxygen. Nitrogen oxides are also problematic for urban dwellers because sunlight causes hydrocarbons and nitrogen oxides to react and form ozone. Even at low concentrations, ozone damages the body's cells and tissues and causes respiratory ailments. [The next sentence is not about air quality.] Although carbon dioxide is not directly harmful to us since we exhale a large quantity of it every day, it is believed to be a greenhouse gas, that is, it may affect global temperatures.
|Region Studied||LA Basin||Germany||Ideal||Internal Combustion|
|Amount of Electricity from Coal or Oil||21%||49%||100%||(for comparison)|
While studies of the pollution-reducing ability of electric vehicles in California are quite favorable, they cannot be applied to the rest of the world as a whole. The truth is that when using electricity generated from dirty sources such as coal and oil, electric vehicles may actually create more of some pollutants than comparable internal combustion engine vehicles. A report by the U.S. General Accounting Office (GAO) cited a German study that estimated the environmental impact of electric vehicles with two distinct energy mixes: one comprised of only 49% coal-fired electricity, and one comprised solely of coal-fired electricity . The estimates provided by the study are given in table 1. Assuming that 49% of an electric vehicle's charging energy being derived from coal, the study found that electric vehicles would cause comparable levels of nitrogen oxides and carbon dioxide to be emitted, and that sulfur oxide emissions would increase by a factor of 10 . Furthermore, when assuming that an electric vehicle is charged with 100% coal-fired electricity, the study estimated that the electric vehicles would emit 150% more carbon dioxide, 250% more nitrogen oxides, and 2400% more sulfur oxides than a comparable internal combustion engine vehicle .
While these coal-fired electric vehicles will emit more of some pollutants, they still will emit less carbon monoxide and hydrocarbons than a comparable internal combustion engine vehicle. The GAO reported noted that mandatory pollution controls at power plants ensure that electric vehicles will always produce less carbon monoxide and hydrocarbons than internal combustion engine vehicles, regardless of the source of the electricity . The German study offers some insights into how electric vehicles would perform in the United States. Their value of 49% represents the portion of German electricity generation that is based on coal, and is close to that of the United States, which, as a whole, derives 55% of its electricity from coal and oil . We can expect similar results for the United States, namely, that while electric vehicles produce much less carbon monoxide and hydrocarbons, they use similar levels of nitrogen oxides and carbon dioxide, and increased levels of sulfur oxides.
Not all pollutants related to electric vehicles arise from t he generation of electricity. Any discussion of the environmental impact of electric vehicles must also take into consideration the problems associated with the manufacturing and disposal of their batter packs. The typical electric vehicle contains no less than half a ton of batteries (often of the lead-acid variety) that need to be replaced every 20-25 thousand miles . There have not been any definitive studies on the pollution caused by the manufacture and disposal of these batteries, as no one is sure what the batteries used in production electric vehicles of the next century will be like. Furthermore, since current electric vehicle batter packs have not yet begun to produced on a large scale, say, in the million of units per year, there is little hard data available on their environmental impact. The prevailing opinion is that the batteries will not pose much of an environmental problem because of their large weight and high cost. The rationale is that since electric vehicle battery packs weigh several hundred pounds and cost several thousand dollars, they will most likely be replaced by certified repair centers, that will return them to the manufacturer for recycling. Unlike regular car batteries, it will not be economical to simply throw electric vehicle battery packs away when they can no longer hold a charge. The batteries will most likely be refilled, and the original contents recycled, just as motor oil is today.
The use of electric vehicles would allow even further decreases in auto emissions over time because only about 10,500 power plants will have to be monitored, maintained, and upgraded as opposed to the over 100 million private automobiles.  Despite the vast amounts of money spent each year in this country to maintain the emissions systems of gas-powered automobiles, cars generally emit more pollution as they age. Deterioration of the catalytic converter and other critical emissions control components eventually leads to an increase of emissions from older cars. Electric vehicles would not suffer from this problem because electric power plants receive more maintenance at regular intervals than would be afforded to a private automobile. In fact, the U.S. Government already maintains a strict testing schedule for electric power plants, making sure that they comply with emissions standards once a month. Another advantage of this centralized approach is that any new pollution reduction technologies can be universally applied to every electric vehicle by simply upgrading the power plants.
Because so many tradeoffs in local versus global pollution are involved, it is impossible to say with certainty that electric vehicles provide the best short term solution to transportation related pollution. The example of sulfur oxides in the Northeast is but one instance where electric vehicles may prove more harmful to the environment than their internal combustion counterparts. it is likely that some localities may be better served by internal combustion engine vehicles with more stringent pollution controls. Government officials in Germany have concluded that, for the time being, catalyst-equipped internal combustion engine vehicles would reduce pollution more than electric vehicles . They came to this conclusion because most of Germany's overflow electricity generation is coal-based, that is to say, as electricity demand increases, the percentage coming from coal-fired power plants increases. It was their final opinion that "the broad-scale introduction of electric vehicles into the Federal Republic of Germany is justifiable only if the zero emission at the place of use is considered more important than the increased emissions at the power plant." Many regions around the world will face similar decisions regarding the importance of local pollution reduction versus the effect on the global environment.
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