Pollutants derived from automobile operation have begun to pose environmental problems of considerable magnitude. It has been calculated, for example, that 70% of the carbon monoxide, 45% of the nitrogen oxides, and 34% of the hydrocarbon pollution in the United States can be traced directly to automobile exhausts.
In addition, rubber (which wears away from tires), motor oil, brake fluid, and other substances accumulate on roadways and are washed into streams, with effects nearly as serious as those of untreated sewage. A problem also exists in disposing of the automobiles themselves when they are no longer operable.
In an effort to improve the situation, the U.S. government has enacted regulations on the use of the constituents of automobile exhaust gas that are known to cause air pollution. These constituents fall roughly into three categories: hydrocarbons that pass through the engine unburned and escape from the crankcase; carbon monoxide, also a product of incomplete combustion; and nitrogen oxides, which are formed when nitrogen and oxygen are in contact at high temperatures. Besides their own toxic character, hydrocarbons and nitrogen oxides undergo reactions in the presence of sunlight to form noxious smog.
Carbon monoxide and hydrocarbons are rather easily controlled by the use of high combustion temperatures, leaner fuel mixtures, and lower compression ratios in engines. Unfortunately, the conditions that produce minimum emission of hydrocarbons tend to raise emission of nitrogen oxides. To some extent this difficulty is solved by adding recycled exhaust gas to the fuel mixture, thus avoiding the oversupply of oxygen that favors formation of nitrogen oxides.
When a vehicle is new, it tends to run fairly clean and does not cause much pollution other than tail pipe emissions and hydrocarbons that evaporate from the fuel tank while the vehicle is parked. Hydrocarbons are also released into the air when we fill our gas tanks. If you don’t believe me, take a sniff next time you fill up. Don’t breath too deeply though as the vapors leaking into the air contain several known or suspected carcinogens. Topping off the tank also tends to cause fuel spills that will evaporate quickly and add to the hydrocarbon levels in the air. As the vehicle begins to age, other systems will eventually start to wear and create additional pollution problems.
In the past century, the automobile has come a far way from Henry Ford’s Model T. In the United States there has always been a high demand for cars, and with that demand comes the need for speed, and a need to have the best. And that is what major automobile industries have been giving our society because they know that they can profit greatly from it. These industries know what sells and they take advantage of it. In order to improve automobiles so that they meet these needs of our society, automobile industries turn to technology. Technology is what has turned the Ford Model T into a Ford Mustang 5.0. Of course with this technology comes flaws. The biggest and most obvious flaw is pollution. Because of pollution, we find ourselves asking the question of whether this technology has helped our society more than it has hurt it. And now that we have identified the problem, how can it be fixed, and how will fixing the problem of automobile pollution affect society also?
The automotive industry has made steady improvements in the area of fuel efficiency, and they promise more improvements to come. Automotive engineers have cut the weight of cars in half in the last 25 years. The miles-per-gallon rating of passenger cars has improved 39 percent in the last ten years. Unfortunately, fuel consumption has increased by 19 percent. According to Vital Signs, the increased emissions from the world’s vehicles lead to global warming, acid rain, smog, and the disastrous health effects of air pollution. The internal combustion engines in cars produce oxides that combine with water vapor in the air to form acid rain. Smog is formed from the chemical reaction between unburned hydrocarbons and the oxides of nitrogen in automobile exhaust. The tons of carbon dioxide produced by burning gasoline is the leading cause of the greenhouse effect, which causes global warming. Vehicles contribute to an estimated 60-70 percent of urban air pollution. Automobiles do not maximize the energy they are producing, creating unnecessary waste. The largest area of needed improvement in the automobile is energy efficiency. Only 13 percent of the energy used by today’s vehicles is used for propulsion. The most promising solution to this problem is alternative fuel vehicles.