Meeting #3

GREENER CARS MAY WARM THE WORLD

Cars equipped with catalytic converters emit higher quantities of a gas that contribute to global warming and deplete stratospheric ozone than cars without them, according to tests carried at in Sweden and France.

A catalytic converter is a cylindrical box connected to the exhaust of a petrol car. It reduces some of the pollutants that petrol engines produce, such as hydrocarbon, carbon monoxide, and nitrogen oxide. A modern three ways catalytic converter (TWC) can eliminate up to 80% of these pollutants.

All new cars in the US are fitted with catalytic converters in order to reduce pollution and the European Commission is considering the following suit by making it compulsory for all new models of cars in Europe to be fitted with TWCs.

Nitrous oxide is a by-product of the process within catalytic converters. Until recently, the researchesr had thought that nitrous oxide was not a significant pollutant from motor vehicles.

However, researcher at the Swedish Environmental Research Institute (SERI) in Gothenburg, the Vehicle Emission Research laboratory in Studsvik and the Petroleum Institute at Rueil-Malmaison in France, have found that level of nitrous oxide rose significantly in cars with catalytic converters.

The researchers looked at nitrous oxide emission from cars with petrol engines, both with and without TWCs, and also at emissions from cars with diesel engines. All the studies found that cars equipped with TWCs produced more nitrous oxide than either a car without a TWC or a diesel-powered vehicle. The researcher at SERI found that vehicles with TWCs produced up to five times as much as nitrous oxide as cars without them.

The French team also found that cars fitted with TWCs produced many times more nitrous oxide than cars without them. The difference, however, is the greatest at low speeds after a cold start. All three groups showed that the complex chemistry occurring within a TWC forms nitrous oxide.

Concern about the role of nitrous oxide in the atmosphere dates back to the early 1970s, when scientists feared that emission of the gas from the engines of high flying aircraft such as Concord would destroy ozone in the stratosphere. Although later calculation showed that this risk was slight, the research led to the investigation of the role of chlorofluorocarbons (CFCs) as destroyers of ozone.

More recently, realized that nitrous oxide contributes significantly to the warming of the world, through the greenhouse effect. Like carbon dioxide, methane, CFCs and other gases produced as a result of human activities, nitrous oxide traps the infrared heat that would be otherwise radiated into space.

Nitrous oxide ranks behind carbon dioxide, methane and CFCs in its contribution to the greenhouse effect, but this does not mean that its contribution can be ignored.

One of the key problems with the greenhouse effect is that there are so many gases that seem to make a minor contribution that it is hard to blame anyone pollutant. Together, all these gases apart from carbon dioxide more than double the effect of CO_2. As Stephen Schneider of the US National Center for Atmospheric Research has put it, “the little guys nickel and dime their way to contribute half the problem”.

According to one of the researchers from SERI, no one yet knows whether the amount of nitrous oxide produced by catalytic converters will have a significant contribution to global warming or to the depletion of stratospheric ozone.

Researchers also do not understand the chemical processes by which nitrous oxides are produced within TWCs so the converters cannot yet be modified to prevent this gas from forming.

TWCs do, however, have a significant role in reducing other oxides of nitrogen, nitrogen monoxide (NO) and nitrogen dioxide (NO₂), which produce nitrous oxide when they are deposited on surfaces. So cars without TWCs could produce more nitrous oxide indirectly.

Meanwhile, the results have caused a stir in some parts of Scandinavia-one Swedish newspaper overreacted to the results and published a story with a headline which read: “Catalytic converters destroy the ozone layer”.

A. COMPREHENSION QUESTIONS.

1.      What is the function of the catalytic converter?

2.      What is the difference between cars with TWCs and cars without TWCs?

3.      How is the role of nitrous oxide to the warming of the world?

4.      So what does “green car’ mean?

5.      What does the text talk about?

B. ENRICHMENT

1. Can you find the contradiction about things to discuss in the text? What is the contradiction? Why were they contradictive to each other?

2. By considering all the possibilities, what do you suggest whether the car should be equipped with TWC or not?

Item to learn:

1.    Finding explicit and implicit information.

2.    Understanding sentences with modal auxiliaries.

3.    Understanding comparison

Indicator of completion:

1.      Able to identify detail description of an object.

2.      Able to compare objects

3.      Able to make inferences.

4.      Able to give a suggestion of future action

Benchmarking:

1.    Why did people invent TWC?

2.    Basically, TWC has two sides: the advantage and the disadvantage. Mention them!

3.    Considering together the advantage and the disadvantage of TWC, what should people do?