2019年AP英语语言简答题真题+答案+PDF下载
Source A
Winchell, Joshua. “Wind Turbines.” U. S. Fish and Wildlife Service National Digital Library, 25 Mar. 2009, digitalmedia.fws.gov/cdm/ ref/collection/natdiglib/id/6861.
The photograph below was taken for the United States Fish and Wildlife Service.
Source B
Layton, Julia. “How Wind Power Works.” HowStuffWorks, 9 Aug. 2006, science.howstuffworks.com/environmental/ green-science/wind-power.htm.
The following is excerpted from a popular Web site dedicated to explaining various processes.
On a global scale, wind turbines are currently generating about as much electricity as eight large nuclear power plants. That includes not only utility-scale turbines, but also small turbines generating electricity for individual homes or businesses (sometimes used in conjunction with photovoltaic solar energy). A small, 10-kW-capacity turbine can generate up to 16,000 kWh per year, and a typical U.S. household consumes about 10,000 kWh in a year.
A typical large wind turbine can generate up to 1.8 MW* of electricity, or 5.2 million KWh annually, under ideal conditions—enough to power nearly 600 households. Still, nuclear and coal power plants can produce electricity cheaper than wind turbines can. So why use wind energy? The two biggest reasons for using wind to generate electricity are the most obvious ones: Wind power is clean, and it’s renewable. It doesn’t release harmful gases like CO2 and nitrogen oxides into the atmosphere the way coal does . . . and we are in no danger of running out of wind anytime soon. There is also the independence associated with wind energy, as any country can generate it at home with no foreign support. And a wind turbine can bring electricity to remote areas not served by the central power grid.
But there are downsides, too. Wind turbines can’t always run at 100 percent power like many other types of power plants, since wind speeds fluctuate. Wind turbines can be noisy if you live close to a wind plant, they can be hazardous to birds and bats, and in hard-packed desert areas there is a risk of land erosion if you dig up the ground to install turbines. Also, since wind is a relatively unreliable source of energy, operators of wind-power plants have to back up the system with a small amount of reliable, non-renewable energy for times when wind speeds die down. Some argue that the use of unclean energy to support the production of clean energy cancels out the benefits, but the wind industry claims that the amount of unclean energy that’s necessary to maintain a steady supply of electricity in a wind system is far too small to defeat the benefits of generating wind power.
Potential disadvantages aside, the United States has a good number of wind turbines installed, totaling more than 9,000 MW of generating capacity in 2006. That capacity generates in the area of 25 billion kWh of electricity, which sounds like a lot but is actually less than 1 percent of the power generated in the country each year. As of 2005, U.S. electricity generation breaks down like this:
• Coal: 52%
• Nuclear: 20%
• Natural Gas: 16%
• Hydropower: 7%
• Other (including wind, biomass, geothermal and solar) 5%
The current total electricity generation in the United States is in the area of 3.6 trillion kWh every year. Wind has the potential to generate far more than 1 percent of that electricity.
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