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 CO2. 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?
