Table of Contents
BEST IELTS Academic Reading Test 501
IELTS ACADEMIC READING TEST 501 – PASSAGE – 1
IELTS ACADEMIC READING TEST – 501
READING PASSAGE – 1
WIND TURBINES
WIND AS A SUITAINABLE ENERGY SOURCE
Wind turbines capture energy from the wind to create instant clean, green electricity and produce no pollution or greenhouse gases while they operate, but many people think they are ugly and destroy the look of wherever they are placed, whether it is on land or sea. Let’s take a look at how they work. A turbine is a rotary mechanical device that captures energy from water or air flow and converts it into another form of energy.
Energy produced by a turbine can be used to generate electrical power when combined with a generator. A windmill is a classic turbine, but virtually all electricity, including that from wind power, hydropower and coal burning generators, is created using some kind of turbine.
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The visible part of a wind turbine is the huge, curved rotor blades. The shape of these is similar to the wings of an airplane with the front edge being thicker than the back edge. This form is called airfoil, and is important for overcoming air résistance, or drag. On an airplane’s wings, airfoil creates lift, but on a wind turbine it causes the central axle to rotate as the rotor blades spin. The longer the blades are, the more energy the wind turbine generates. As the amount of energy produced by a wind turbine can vary, supply to the grid is stabilized by linking a large number of wind turbines in different areas.
Of course the blades of the turbine are what you see, but the main workings of the wind turbine take place inside the nacelle, which is the cylinder-shaped main section of the wind turbine, mounted on the tower. Inside the nacelle, closest to the blades, is the gearbox. This helps convert the slow spinning speed of the blades into the higher rotation of the central axle, powering more electricity. Normal industrial gearboxes decrease the speed of a generator, but wind turbine gearboxes do the opposite.
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The gearbox is at the rear of the generator, which is the part of the wind turbine that turns kinetic energy into storable electricity. The electricity created by the generator is transmitted to a transformer on the ground via a cable. The function of the transformer is to convert the electricity to a higher voltage so that it can be directed to a local grid for distribution. A typical land wind turbine can produce around 6 million kWh in a year, which is enough electrical energy for the needs of 1,500 households.
At the rear of the nacelle, there is a device for measuring wind speed and direction called an anemometer. This directs what is called a yaw system to rotate the top of the turbine into the oncoming wind to catch the greatest amount of energy. When wind conditions are too strong, the rotor blades can be blocked by brakes to reduce the possibility of damage.
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The blades are about 80 metres in width and the tower is about 95 metres high. This height enables more energy to be trapped, as wind has greater speed when there is nothing to block its path. For the same reason, they need to be far apart from each other. Of course, wind isn’t constant, and most are usually idle for about 15 per cent of the time, but placement needs to be on a site with a high level of constant wind.
If they are placed in an area where there is discernible wind only 30 per cent of the time, it would hardly create enough electricity to power a thousand homes. Bigger offshore versions with constant wind exposure can generate enough for 6,000 homes.
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Wind power is, however, an inconsistent form of energy and an efficient power grid could not function effectively with wind turbines as its sole source of electricity. For a 100 per cent guarantee of energy, there needs to be a mixture of other sources such as nuclear, hydro, coal-powered, natural gas or solar energy. But wind power can make a major contribution. Denmark produces 42 per cent of its electricity needs with wind power.
The most visible disadvantage of creating wind power is that it takes up a lot of space. Placed on farmland, wind turbines take up minimal land area. Turbines mounted at sea are very efficient but they are more difficult to maintain and very costly to mount. Landowners and farmers often have objections to installing new power lines and claim that wind turbines destroy the view, though many enjoy the guaranteed income for a quarter of a century for renting out their land, 95 per cent of which they can still continue to use.
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There are great advantages to using wind turbines, mainly that they are sustainable. Once constructed, they have no emissions and the energy created is without limit and with little further cost. Their construction does involve a lot of metal, so that has some environmental impact. However, of all forms of power generation they have the lowest carbon emissions, even including solar installations and biomass plants. And despite the very high costs of building the turbines, in the long run they are an inexpensive option per kilowatt produced, costing half the price of nuclear and two-thirds that of coal-burning plants.
QUESTIONS 1-5
Choose NO MORE THAN TWO WORDS for each answer.
Questions 6-8
Choose the correct letter, A, B, C or D.
6. Why is an airfoil shape used for the blades of a wind turbine?
A. It makes them rise.
B. It makes them curve.
C. It makes them turn.
D. It makes them drag.
7. The part of the wind turbine that controls the speed of the central axle is the
A. gearbox.
B. rotor blades.
C. generator.
D. transformer.
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8. The yaw drive
A. faces the direction of the wind.”
B. changes the position of the rotor blades.
C. rotates the central axle
D. calculates wind speed and direction.
Questions 9-13
Do the following statements agree with the information given in Reading Passage 1?
In boxes 9-13 on your answer sheet, write
TRUE – if the statement agrees with the information
FALSE – if the statement contradicts the information
NOT GIVEN – if there is no information on this
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9. A wind turbine is about 80 metres high.
10. Wind turbines in the sea create more electricity than those on land.
11. Wind power should be used in conjunction with other forms of energy production.
12. A disadvantage of wind turbines on farmland is that farmers lose money.
13. Solar energy systems are cheaper to install than wind turbines.
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ANSWERS
1. ROTOR BLADES
2. NACELLE
3. GENERATOR
4. TRANSFORMER
5. ANEMOMETER
6. C
7. A
8. B
9. FALSE
10. TRUE
11. TRUE
12. FALSE
13. NOT GIVEN
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