NEW YORK (Reuters) Electric cars will not be dramatically cleaner than autos powered by fossil fuels until they rely less on electricity produced from usual coal-fired power plants, scientists said on Monday.
"For electric vehicles to become a major green alternative, the power fuel has to move away from coal, or cleaner coal technologies have to be developed," said Jared Cohon, the chair of a National Research Council report released on Monday.
About half of U. S. power is generated (产生) by burning coal, which gives off many times more of traditional pollutants than natural gas, and about twice as much of the main greenhouse gas carbon dioxide.
Nuclear and renewable power would have to generate a larger portion of U. S. power for electric cars to become much greener compared to gasoline-powered cars, Cohan, who is president of Carnegie Mellon University, said in an interview.
Advances in coal burning, like capturing carbon at power plants for permanent burial underground, could also help electric cars become a cleaner alternative to vehicles powered by fossil fuels, he said.
Pollution from energy sources did $120 billion worth of damage to human health, agriculture and recreation in 2008, and electricity was responsible for more than half of file damage, said the NRC report.
Electric cars have their benefits such as reducing imports of foreign oil. But they also have hidden costs.
Materials in electric car batteries are hard to produce, which adds to the energy it takes to make them. In fact, the health and environmental costs of making electric cars can be 20 percent greater than usual cars, the report said.
The report estimated that electric cars could still cost more than gas-powered cars to operate and manufacture in 2030 unless U. S. power production becomes cleaner.
64. Why are electric cars not clean enough?
A. Because they run too slowly.                         B. Because they are too expensive.
C. Because they rely on coal-fired power.           D. Because they give off more carbon dioxide.
65. We can infer from the passage that ________.
A. electric cars will soon take the place of gas-powered cars
B. no one holds hope for electric cars at present
C. electric cars waste more energy than before
D. some people believe that electric cars are more cleaner
66. Which of the following is not mentioned as a way to make electric cars cleaner?
A. Developing cleaner coal technologies.            B. Making electric cars run faster.
C. Generating more nuclear power.                    D. Making advances in coal burning.
67. What kind of attitude the writer holds towards the future of electric cars?
A. The writer thinks highly of electric cars.
B. The writer believes electric cars will disappear in the end.
C. The writer thinks it' s hard to popularize electric cars at present.
D. The writer thinks it' s impossible for us to use electric cars before 2030.

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