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下面是
TPO 9
Reading
Car manufacturers and governments have beeneagerly seeking a replacement for the automobile’s main source of power, theinternal-combustion engine. By far the most promising alternative source ofenergy for cars is the hydrogen-based fuel-cell engine, which uses hydrogen tocreate electricity that, in turn, powers the car. Fuel- cell engines haveseveral advantages over internal-combustion engines and will probably soonreplace them.
One of the main problems with theinternal-combustion engine is that it relies on petroleum, either in the form ofgasoline or diesel fuel. Petroleum is a finite resource; someday, we will runout of oil. They hydrogen needed forfuel-cell engines cannot easily be depleted. Hydrogen can be derived fromvarious plentiful sources, including natural gas and even water. The fact thatfuel-cell engines utilize easily available, renewable resources makes themparticularly attractive.
Second, hydrogen-based fuel cells are attractivebecause they will solve many of the world’s pollution problems.
An unavoidable by-product of burning oil iscarbon 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 beeconomically competitive because people will spend less money to operate afuel-cell engine than they will to operate an internal-combustion engine. Thisis true for one simple reason: a fuel-cell automobile is nearly twice asefficient in using its fuel as an automobile powered by an internal- combustionengine is. In other words, the fuel-cell powered car requires only half thefuel energy that the internal-combustion powered car does to go the samedistance.
Listening
Professor
The reading is correct in pointing out theproblems associated with oil-powered cars. Yes, oil is a finite resource, andyes, burning oil harms the environment. However, the reading is way too optimisticin its assessment of hydrogen-based fuel-cell engines. Hydrogen is not thesolution to these problems.
First, hydrogen is not as easily availableas the passage indicates. Although it’s present in common substances likewater, 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 liquidhydrogen is a highly artificial substance. It’s technologically very difficult toproduce and store liquid hydrogen. For example, it must be kept very very coldat minus 253 degrees Celsius. Imagine the elaborate cooling technology that’srequired for that! So hydrogen is not such a practical and easily
available substance, is it?
Second, using hydrogen would not solve thepollution problems associated with cars. Why? Producing pure hydrogen creates alot of pollution. To get pure hydrogen from water or natural gas, you ah vetouse a purification process that requires lots of energy that’s obtained byburning coal or oil. And burning coal and oil creates lots of pollution. Soalthough the cars would not pollute, the factories that generated the hydrogenfor the cars would pollute.
Third, there won’t necessarily be any costsavings when you consider how expensive it is to manufacture the fuel-cellengine. That’s because fuel-cell engines require components made of platinum, avery rare and expensive metal. Without the platinum components in the engine,the hydrogen doesn’t undergo the chemical reaction that produces theelectricity to power the automobile. All the efforts to replace platinum with acheaper material have so far been unsuccessful.
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