As already known, our world has been and at present, is continuing to suffer on account of man's brutalities and carelessness. This is one of the fundamental dilemmas, which had arised many centuries ago, our modern technological society has to confront. Throughout the years, science has been enhancing remarkably and, not too far behind followed the ecological problems. After the Industrial Revolution, advancement in technology was considered the sole enemy of the environment after humanity.
Engines and Pollution
An engine is the main source that is responsible for the large amount of hazardous emissions produced by a vehicle. For this reason, the usage of any vehicle, as simple as a small car, is considered a contaminating everyday activity. You might be asking yourself: How can one simple car be responsible for the damaging of our environment? One additional simple car on the road is a contributor. The summation of all the emissions of the vehicles on the road is the cause.
The Combustion Process
The combustion process is the process in which all the burning of gasoline or diesel fuel takes place. This procedure actually powers vehicles causing it to move. Also, during this process, pollution takes into effect. It causes a vehicle to exhaust by-products and evaporate fuel.
Diesel fuel and gasoline are composed of mixtures of compounds of carbon and hydrogen known as hydrocarbons. The oxygen in the air combined with the hydrogen and carbon in the fuel, in a "perfect" engine, will form compounds of water and carbon dioxide. The remaining gas in the air, nitrogen, will not suffer any change. These explanations can be easily expressed in the following chemical equations:
Combustion process of a typical engine:
AIR (oxygen and nitrogen) + FUEL (hydrocarbons)--->Water + Carbon Dioxide + Carbon Monoxide + Nitrogen Oxides + Unburned Hydrocarbons
Combustion process of a "perfect" engine:
AIR (oxygen and nitrogen) + FUEL (hydrocarbons)--->Water + Carbon Dioxide + Natural Nitrogen
As you can see, the previous equations also portray how a "perfect" engine, in comparison with the typical engine, is less hazardous to the environment.
In the combustion process, many chemical reactions originate hazardous compounds produced in the engine of a vehicle to later be expulsed into the environment. For instance, numerous nitrogen oxides are formed when oxygen and nitrogen atoms in the air react under high temperature and pressure in the engine forming a component of smog, which is also known as ground-level ozone. It also contributes to the development of acid rain.
The production of hydrocarbons is the most prevalent and obstinate urban air pollution problem that exists. It all begins when fuel molecules do not burn or burn only partially in the engine it causes hydrocarbon emissions. This then reacts with the sunlight and nitrogen oxides making a large contribution to the formation of ozone. The resultant product harms the lungs, irritates the eyes, and causes respiratory difficulties. Some of these expulsed hydrocarbons are known to be very toxic and are even capable of causing major health problems such as cancer.
Other compounds that involve carbon (carbon monoxide and carbon dioxide) are also emitted. Carbon monoxide occurs when carbon in the fuel is partially oxidized. When it is completely oxidized, it is then known as carbon dioxide. This product does not affect directly human health, although, it contributes to global warming. On the other hand, carbon monoxide reduces the flow of oxygen in the bloodstream and is very harmful for people with heart diseases.
All the emissions of pollutants are not only due to the exhausting of a vehicle. Some percentage of this perilous process is owing to the evaporation of fuel. The evaporation of fuel causes hydrocarbon toxins escape into the air. These kind of emissions are reprehensible for the majority of the amount of hydrocarbons that are being exposed to open air and for the increase in the ozone level.
Evaporative expulsions of a vehicle can take place in various ways. During the day, when the temperature rises, the amount of the evaporation of fuel also increases. The vehicle's fuel tank begins to receive heat from the sun and gasoline vapors emerge. This kind of emission is called diurnal. Another kind of evaporative emissions are running losses. This occurs when a car is running and its engine, which possesses much heat, continues to vaporize gasoline. Even when a car is in cessation if it had been running for a long period of time it gasoline will continue to vaporize. This is known as hot soak. Another evaporative expulsion possibility is refueling. At some point a car is going to need refueling. Since there will always be gasoline vapors present in the fuel tank, they will escape when it is refueled. The liquid fuel will replace the gas in the tank.
Is Anyone Taking Control?
The government and environmental organizations, such as the EPA (Environmental Protection Agency), were mostly noticeable for taking action in environmental affairs in the decade of the 70s. Many laws forcing people to limit the level of contamination produced by vehicles emerged. In 1970, the EPA issued the Clean Air Act, which gave the agency authority to control the pollution of vehicles. With time, emission control policies have been enhanced and became more restrictive. The EPA has the endowment to systematize standards concerning the amount of pollution motor vehicles are allowed to emit. Auto-manufacturers, trying to adjust their products to the standards or limitations set by the agency, employed new and improved engine designs that caused fewer emissions. In addition, many other components were included that helped the reduction of nitrogen oxide. In 1975, catalytic converters were used to reduce hydrocarbon and carbon monoxide emissions. This led to the introduction of unleaded gasoline since lead inactivates with the converters. As a result, related environmental and health issues suffered a contraction.
By the beginning of the following decade, new forms of technology emerged along with more improved emission control systems, such as the "three-way" catalyst. This kind of catalytic converter helped minimize the amount of hydrocarbons, nitrogen oxides and carbon monoxide.
In 1990, with the Clean Air Act, automobile expulsions have continued to decline. Besides the progress in technology, improvements in controlling vehicle pollution are due to the issuing of laws that served to protect the environment.
© 2000 by ThinkQuest team C006011