托福閱讀聽力寫作 demo 4
托福閱讀聽力寫作 demo 4 by David pai Email: ginway2012@gmail.com
TP09
Reading
Car manufacturers
and governments have been eagerly seeking a replacement for the automobile's
main source of power, the internal-combustion engine. By far the most promising
alternative source of energy for cars is the hydrogen-based fuel-cell engine,
which uses hydrogen to create electricity that, in turn, powers the car.
Fuel-cell engines have several advantages over internal-combustion engines and
will probably soon replace them.
One of the main
problems with the internal-combustion engine is that it relies on petroleum,
either in the form of gasoline or diesel fuel. Petroleum is a finite resource;
someday, we will run out of oil. The hydrogen needed for fuel-cell engines
cannot easily be depleted. Hydrogen can be derived from various plentiful
sources, including natural gas and even water. The fact that fuel-cell engines
utilize easily available, renewable resources makes
them particularly attractive.
Second,
hydrogen-based fuel cells are attractive because they will solve many of the
world's pollution problems. An unavoidable by-product of burning oil is carbon
dioxide, and carbon dioxide harms the environment. On the other hand, the only byproduct
of fuel-cell engines is water.
Third, fuel-cell
engines will soon be economically competitive because people will spend less
money to operate a fuel-cell engine than they will to operate an
internal-combustion engine. This is true for one simple reason: a fuel-cell
automobile is nearly twice as efficient in using its fuel as an automobile
powered by an internal-combustion engine is. In other words, the fuel-cell
powered car requires only half the fuel energy that the internal-combustion
powered car does to go the same distance.
Listening
Professor:
The reading is
correct in pointing out the problems associated with oil-powered cars. Yes, oil
is a finite resource, and yes, burning oil harms the environment. However, the
reading is way too optimistic in its assessment of hydrogen-based
fuel-cell engines. Hydrogen is not the solution to these problems.
First, hydrogen is
not as easily available as the passage indicates. Although it's present in
common substances like water, it's not directly useable in that form. For using
a fuel-cell engine, hydrogen must first be obtained in a pure liquid state.
This pure liquid hydrogen is a highly artificial substance. It's
technologically very difficult to produce and store liquid hydrogen. For
example, it must be kept very cold at
minus 253 degrees Celsius. Imagine the elaborate cooling technology that's
required for that! So hydrogen is not such a practical and easily available
substance, is it?
Second, using
hydrogen would not solve the pollution problems associated with cars. Why? Producing
pure hydrogen creates a lot of pollution. To get pure hydrogen from water or
natural gas, you have to use a purification process that requires lots of
energy that's obtained by burning coal or oil. And burning coal and oil creates
lots of pollution. So although the cars would not pollute, the factories that
generated the hydrogen for the cars would pollute.
Third, there won't
necessarily be any cost savings when you consider how expensive it is to
manufacture the fuel-cell engine. That's because fuel-cell engines require components
made of platinum, a very rare and expensive metal. Without the platinum
components in the engine, the hydrogen doesn't undergo the chemical reaction
that produces the electricity to power die automobile. All the efforts to
replace platinum with a cheaper material have so far been unsuccessful.
Summary:
In the lecture, the
professor literally analyze the benefits of the hydrogen-based fuel-cell
engines in the reading by the author, -- inclusive of recyclable and infinite
resources, the ultimate solution of
world’s environmental protection, and economic effect—and conclude the misapplication
of the engine. Below is the detailed.
For the first, the professor think
hydrogen fuel quite a impractical resource in face with the difficult technique
issues in acquiring and storing the pure fuel. Specifically speaking, super-low
temperature is too toilsome/laborious/arduous to be achieved in order to make
the pure liquid fuel-the culprit to blame.
Second, the professor offer
a another sound mechanism to reverse ‘environmental-protection ’ as a fallacy
.The final production of pure liquid fuel lead to more proliferating pollution
rather than reducing it. In total, the amount of pollutants made for the fuel overwhelm
the benefit of use of it. Obviously, this is not a good deal.
Last, the professor
pinpoint (that ) in light of the manufacturing fuel-cell engines, a special indispensable
and costly metal, platinum, is currently irreplaceable or hard to find
alternative. And this can can make the engine-making come to halt.
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