Skill 5.4

At the moment, no one is proposing the creation of a solar power station the size of a small country. But a relatively ​ (a)   -developed technology exists, which ​ (b)   say could turn the Sahara's heat and sunlight into a major ​ (c)   of electricity - Concentrating Solar Power (CSP). Unlike solar panels, which convert sunlight directly into electricity, CSP utilises mirrors which focus light on water pipes or boilers to produce very hot steam to ​ (d)   the turbines of generators. Small SP plants have produced power in California's Mojave Desert since the 1980s. The Sahara Forest Project proposes building SP plants in areas below sea level [the Sahara has several such depressions] so that sea water can flow into them. This water would then be purified and used for powering turbines and washing dust off the mirrors. Waste water would then supply irrigation to areas around the stations, creating lush oases - ​ (e)   the 'forest' in the group's name.

• well
• good
• proponents
• supporter
• source
• resource
• operate
• work
• hence
• therefore

But producing significant ​ (a)   of electricity means building huge arrays of mirrors and pipes ​ (b)   hundreds of miles of remote desert, which is expensive. Gerry Wolff, an engineer who heads DESERTEC, an international consortium of solar-​ (c)   scientists, says they have ​ (d)   it will cost about $59 billion to begin ​ (e)   power from the Sahara by 2020.

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Apart from tourism, what other environment problems are common in the world today?

Whose responsibility is it to deal with these problems?

What can ordinary people do to protect the environment?

The diagrams explain ​ (a)   wind turbines ​ (b)   be ​ (c)   and ​ (d)   they look ​ (e)   .

• placed
• what
• like
• where
• should
• how

​ (a)   to the diagrams, there are three ​ (b)   positions for a turbine. A large ​ (c)   turbine would be built high up ​ (d)   where the wind is strongest, and these turbines can ​ (e)   1.5 megawatts of power.

• According
• possible
• on a hillside
• produce
• industrial
• Owing
• in the hill

On the other hand, smaller turbines that produce about 100 kilowatts of power for ​ (a)   use can be found on ​ (b)   . A ​ (c)   possible position is in the sea. Here, there is less ​ (d)   on the countryside, but winds can ​ (e)   be very strong.

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• house

While the locations may be different, the turbines themselves all have the ​ (a)   special shape. They ​ (b)   of a tall tower made of strong steel and on top of this there are three blades ​ (c)   fibreglass or wood. The turbines are ​ (d)   by a computer which can alter the direction and angle of the blades according to the information it ​ (e)   from a sensor.

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• takes

​ (a)   , ​ (b)   wind turbines are very ​ (c)   , and all turbines need to be ​ (d)   to a lot of ​ (e)   .

• Clearly
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• large
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• wind