PETS背誦閱讀附翻譯

　　Coal-fired Power Plants

　　The invention of the incandescent light bulb by Thomas A. Edison in 1879 created a demand for a cheap, readily available fuel with which to generate large amounts of electric power. Coal seemed to fit the bill, and it fueled the earliest power stations (which were set up at the end of the nineteenth century by Edison himself). As more power plants were constructed throughout the country, the reliance on coal increased. Since the First World War, coal fired power plants have accounted for about half of the electricity produced in the United States each year. In 1986 such plants had a combined generating capacity of 289, 000 megawatts and consumed 83percent of the nearly 900 million tons of coal mined in the country that year. Given the uncertainty in the future growth of nuclear power and in the supply of oil and natural gas, coalfired power plants could well provide up to 70 percent of the electric power in the United States by the end of the century.

　　Yet, in spite of the fact that coal has long been a source of electricity and may remain one for many years (coal represents about 80 percent of United States fossil-fuel reserves), it has actually never been the most desirable fossil fuel for power plants. Coal contains less energy per unit of weight than natural gas or oil; it is difficult to transport, and it is associated with a host of environmental issues, among them acid rain. Since the late 1960’s problems of emission control and waste disposal have sharply reduced the appeal of coal-fired power plants. The cost of ameliorating these environmental problems along with the rising cost of building a facility as large and complex as a coal-fired power plant, have also made such plants less attractive from a purely economic perspective.

　　Changes in the technological base of coal-fired power plants could restore their attractiveness, however. Whereas some of these changes are evolutionary and are intended mainly to increase the productivity of existing plants, completely new technologies for burning coal cleanly are also being developed.

　　火力發(fā)電廠托馬斯愛迪生1879年發(fā)明的白熾燈導致對便宜、易得、可生產(chǎn)大量電能的燃料的需求。

　　煤似乎符合這個要求，并成為第一批電廠的燃料(正是愛迪生本人在19世紀末建造了第一批電廠)。全國到處興建電廠時，對煤的依賴加深了。

　　自第一次世界大戰(zhàn)以來，美國每年約有一半的電力是以煤為燃料的電廠提供的。1986年這些電廠的總發(fā)電能力達到28，900千瓦并且消耗了當年全國開采的九億噸煤的83%�？紤]到核能發(fā)展以及石油、天然氣供應中的不確定因素，到本世紀末，火力發(fā)電廠仍可能為美國提供多達70%的電力。然而，盡管煤長期以來一直是電力的原料之一并且可能會繼續(xù)如此(煤占美國化石燃料儲量的80%)，它卻不是電廠的理想燃料。

　　煤的單位能量含量低于石油和天然氣，而且會導致包括酸雨在內(nèi)的一系列環(huán)境問題。從1960年以來，排放控制和垃圾處理的問題極大地削弱了燃煤電廠的魅力。由于減輕這些環(huán)境問題需要大量資金，而且建造龐大復雜的燃煤電廠的費用不斷上漲，也使得這些電廠從經(jīng)濟角度上不具備吸引力。

　　改變火力發(fā)電廠的基礎技術卻可能恢復它們的吸引力。雖然某些技術改進是漸進的，其目的只是提高現(xiàn)有電廠的生產(chǎn)率，但人們正在開發(fā)全新的清潔燃煤的技術。

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