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陳蕙雅思教材 - 雅思閱讀精選 (Coal-fired Power Plants)
瀏覽數:236

Coal-fired Power Plants

The invention of theincandescent light bulb by Thomas A. Edison in 1879

created a demand for acheap, readily      available fuel withwhich to generate

large amounts of electricpower. Coal seemed to fit the bill, and it fueled    

the earliest powerstations (which were set up at the end of the nineteenth

century by Edisonhimself). As more      power plants wereconstructed

throughout the country,the reliance on coal increased. Since the First

World War,   coal-fired power plants have accounted forabout half of the

electricity produced inthe United States each year.       In 1986such plants

had a combined generatingcapacity of 289, 000 megawatts and consumed 83

percent of the nearly           900 million tons of coal mined in thecountry that

year. Given theuncertainty in the future growth of nuclear     powerand in

the supply of oil andnatural gas, coal-fired power plants could well

provide up to 70 percentof the     electric power in the UnitedStates by the

end of the century.

Yet, in spite of the factthat coal has long been a source of electricity

and may remain one formany  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 containsless energy

per unit of weight thannatural gas or oil; it is difficult to transport,

and it is associated witha host of environmental issues, among them acid

rain. Since the late1960's problems of emission control and waste disposal

have sharply reduced theappeal of coal-fired power plants.  The    cost of

ameliorating theseenvironmental problems along with the rising cost of

building a facility aslarge and      complex  as a  coal-fired  power plant,  

have also made such  plants less attractive from  a

purely economicperspective.

Changes in thetechnological base of coal-fired power plants could restore

their attractiveness,however. Whereas    some of these changesare

evolutionary and areintended mainly to increase the productivity of

existing plants,        completely new technologies for burningcoal cleanly are

also being developed.

火力發電廠湯瑪斯·愛迪生 1879 年發明的白熾燈導致對便宜、易得、可生產大量電能 的燃料的需求。  

煤似乎符合這個要求,並成為第一批電廠的燃料(正是愛迪生本人在 19 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 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 年這些電廠的總發電能 力達到 28900

千瓦並且消耗了當年全國開採的九億噸煤的 83%  考慮到核能發展以及石 油、天然氣供應中的不確定因素,到本世紀末,火力發電廠仍可能為美國提供多達

70% 電力。 然而,儘管煤長期以來一直是電力的原料之一並且可能會繼續如此(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於石油和天然氣,而且會 導致包括酸雨在內的一系列環境問題。 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。  由於減輕這些環境問題需要大量資金,而且建造龐大複雜的燃煤 電廠的費用不斷上漲,也使得這些電廠從經濟角度上不具備吸引力。  

改變火力發電廠的基 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,其目的只是提高現有電廠 的生產率,但人們正在開發全新的清潔燃煤的技術。


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