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 . 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 83 percent 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, coal-fired 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 , 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 1960s 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.
湖南高考英语复习课件牛津译林版模块必修4《Unit 3 Tomorrow’s World》Tomorrow’s world明天的世界
海南省高考英语复习课件:Module 6《War and Peace》(外研版选修6)
海南省高考英语复习课件:Module 4《Carnival》(外研版必修5)
湖南高考英语复习课件牛津译林版模块必修5《Unit 1 Getting along with others》与他人相处
海南省高考英语复习课件:Module 6《Unexplained Mysteries of the Natural World》(外研版必修4)
高考英语复习冲刺训练:外研版选修8 Module3《Foreign Food》(附解析)
湖南高考英语复习课件牛津译林版模块必修2《Unit 1 Tales of the unexplained》未解之谜
海南省高考英语复习课件:Module 4《Music》(外研版选修6)
海南省高考英语复习课件:Module 4《Fine Arts—Western,Chinese and Pop Arts》(外研版必修2)
海南省高考英语复习课件:Module 1《Deep South》(外研版选修8)
《萨利机长》电影精讲(视频)
海南省高考英语复习课件:Module 4《Great Scientists》(外研版必修4)
海南省高考英语复习课件:Module 5《Ethnic Culture》(外研版选修7)
海南省高考英语复习课件:Module 5《The Great Sports Personality》(外研版必修5)
湖南高考英语复习课件牛津译林版模块必修5《Unit 2 The Environment》The environment环境
海南省高考英语复习课件:Module 5《The Conquest of the Universe》(外研版选修8)
海南省高考英语复习课件:Module 3《Literature》(外研版选修7)
海南省高考英语复习课件:Module 5《A Trip Along the Three Gorges》(外研版必修4)
海南省高考英语复习课件:Module 3《Music》(外研版必修2)
湖南高考英语复习课件牛津译林版模块选修7《Unit 2 Fit for life》健康生活
海南省高考英语复习课件:Module 2《Fantasy Literature》(外研版选修6)
海南省高考英语复习课件:Module 6《Old and New》(外研版必修3)
海南省高考英语复习课件:Module 1《Basketball》(外研版选修7)
湖南高考英语复习课件牛津译林版模块必修5《Unit 3 Science versus nature》科学与自然
湖南高考英语复习课件牛津译林版模块必修4《Unit 1 Advertising》Advertising广告
海南省高考英语复习课件:Module 1《Life in the Future》(外研版必修4)
高考英语复习冲刺训练:外研版选修8 Module1《Deep South》(附解析)
海南省高考英语复习课件:Module 6《The Tang Poems》(外研版选修8)
海南省高考英语复习课件:Module 5《Cloning》(外研版选修6)
湖南高考英语复习课件牛津译林版模块必修3《Unit 3 Back to the past》回到过去
不限 |
英语教案 |
英语课件 |
英语试题 |
不限 |
不限 |
上册 |
下册 |
不限 |