Quiz: What You Don’t Know About Wind Energy
Photograph by Pascal Rossignol, Reuters
You've seen those tall white turbines turning on hillsides or on windy plains, but how much do you know about the energy captured from wind?
As early as 200 B.C., wind power was used in China, and later, in Persia. How were the first windmills that appeared in Europe in the Middle Ages different from those earlier turbines?
- They were used to generate electricity.
- They turned on a horizontal axis.
- They turned on a vertical axis.
- They were used to grind grain.
Pumping water and grinding grain were the first recorded uses of wind power, but the iconic early windmills of Europe differed from their forerunners in Persia and China in that they turned on a horizontal axis instead of a vertical one.
Wind energy actually relies on what other force of nature?
- Solar energy
- Water power
- Geothermal power
- The moon's gravitational pull
Wind is caused by the uneven heating of the Earth's surface by the sun.
In the mid-1980s, the diameter of the typical wind turbine rotor, including the hub and the blades, was about 65 feet (20 meters). How did the size of rotors change over the next two decades?
- They are now half the size.
- They doubled in size.
- They tripled in size.
- They are five times larger.
The wind energy industry achieved major advances in power and efficiency with rotors that measure about 330 feet (100 meters) in diameter. By 2011, prototypes with a diameter of about 420 feet (128 meters) were the largest turbines developed.
The Roscoe Wind Complex, with more than 600 turbines on 100,000 acres (40,468 hectares) of cotton farmland south of Abilene, Texas, was the world’s largest wind farm in 2011. It generates enough electricity to power how many homes?
- 1.2 million
- 2.6 million
Roscoe's total capacity of 781.5 megawatts delivers enough energy to power 265,000 Texas homes, says operator E. ON Climate & Renewables.
What wind speed is said to be necessary to make large wind energy systems economically viable?
- 3 meters per second (7 miles per hour)
- 6 meters per second (13 mph)
- 9 meters per second (20 mph)
- 12 meters per second (27 mph)
Large systems are generally said to require wind speeds of 6 meters per second (13 mph.) Stanford University researchers estimate that suitable areas are widespread enough globally that if just 20 percent of potential were captured, it would satisfy the world’s electricity demand seven times over.
According to the U.S. Fish and Wildlife Service, what is responsible for the most bird deaths?
- Building window strikes
- Communications towers
- Wind turbines
Building window strikes may account for 97 million to 976 million bird deaths each year; cars, 60 million; communications towers, 4 to 5 million, the agency says. Wind turbine rotors kill an estimated 33,000 birds annually.
What measure has been shown to significantly reduce bat deaths at wind turbine sites?
- Strobe lights
- Intermittent high-pitched sound
- Reduction in turbine rotations
- No measures have been shown to mitigate bat mortality due to wind turbines.
A slight increase in the speed at which turbines are programmed to begin rotating reduced rotations and cut bat deaths by as much as 93 percent with less than a 1 percent power loss, a published study by researchers at Bat Conservation International found.
Off what coast was the world's first commercial offshore wind facility built?
- Galveston, Texas
- Borkum, Germany
- Kent, in the United Kingdom
- Vindeby, Denmark
The world's first commercial offshore wind facility was built in 1991 off the coast of Vindeby, Denmark, in the Baltic Sea.
How large is the wind energy potential off the coasts of the United States, compared to the nation’s current installed electricity capacity, according to government estimates?
- 10 percent
- 20 percent
- 50 percent
- 100 percent
The U.S. Department of Energy (DOE) estimates that more than 900,000 megawatts, close to total current installed U.S. electrical capacity, of potential wind energy exists off the United States coasts. But as of 2011, the U.S. had no offshore wind installations.
What nation had the largest amount of wind energy capacity installed as of 2010?
- The United States
In 2010, China overtook the United States as leader in installed wind energy capacity, with a building spree that increased its wind power base by 73 percent in just one year.
In what country does wind power provide the largest share of the nation’s electricity?
- The United States
Denmark leads the world in reliance on wind power, which provides 21 percent of its electricity. The next most wind-dependent nation is Portugal, at 18 percent.
By 2010, there were enough wind turbines to generate what percentage of the world’s electricity?
- 2.5 percent
- 5.5 percent
- 10.5 percent
- 20.5 percent
Total installed wind capacity by the end of 2010 was enough to generate 430 terawatt-hours of electricity per year, 2.5 percent of world power demand and more than the total electricity demand of the United Kingdom.
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