VI. Read what people say about different fuels and energy sources. What text is mainly about the following? Match the appropriate statement and the text.

1. public perception of energy and the energy industry

2. the effects on the environment of different sources of energy

3. the availability of renewable sources

4. the reliability and efficiency of fossil fuels

a) Coal and lignite are the most reliable fuels. We’ll depend on them more as gas and oil disappear. There may be a few problems with emissions, buy these can easily be solved. They’re also very versatile and can be used to produce electricity and heat our homes efficiently.

b) Fossil fuels are harmful; think how they affect our atmosphere and countryside. We can’t build our future energy planning on them. We have to think differently. The sun is a clean energy source, and the potential for providing us with power is enormous! What’s more we can install solar sells on buildings, which will reduce the requirement for large power stations.

c) Solar power is good as far as it goes, but what do we do when the sun isn’t shining? In some countries there is often cloudy sky, and in some countries there are only four hours of sunlight per day in winter. Wind on the other hand is always at our disposal – more than the sun anyway. We can use this source to cover our needs.

d) The most important thing is to educate people about energy. It may be true that fossil fuels and other sources have some drawbacks, but there are many positive aspects. We should focus on informing people; how they see energy is important.

VII. Questions for discussion:

1. What are renewable and nonrenewable energy sources? What is the difference between them?

2. What is the ratio of renewable and nonrenewable energy sources?

3. What is the role of renewable energy sources in future?

16 Wind power

Reading

I. Read the following words:

turbine, height, metres, tubular, continuously, control, rotor, offshore, measure, hydraulic, aerodynamic.

II. Read and translate the text.

Wind power is renewable and non-polluting and can be used to drive wind turbines. Wind farms consisting of numbers of turbines are increasingly being constructed both on land, usually on high ground, and offshore.

Wind speeds increase with height, so turbines are mounted on towers, typically 50 to 80 metres in height. Most towers are tubular to allow safe access for maintenance.

The rotor blades capture the wind and transfer its power to the rotor hub, which is attached to the low-speed shaft of the turbine. Each rotor blade measures about 27 metres in length and is designed much like an aeroplane wing. The rotor rotates quite slowly, at about 30 r.p.m. The nacelle, the casing at the top of the tower, contains the most important components including the gearbox, generator, and computer. The low-speed shaft transmits power from the hub to the gearbox. It contains pipes for the hydraulic system, which operates the aerodynamic brakes. The gearbox increases the speed of the rotor shaft by about 50 times. The high speed shaft drives the electrical generator. It has a mechanical disc brake for emergency use.

The generator produces electricity by electromagnetic induction. On a large turbine, the power generated is between 600 kW and 3,000 kW. The power is sent by cable to the national grid. The anemometer and wind vane on top of the nacelle measure the speed and direction of the wind respectively and send this information to the computer,

The computer activates the yaw motor, which turns the rotor into the wind. It starts the turbine when the wind reaches about five metres per second. The computer continuously monitors the conditions of the turbine. It controls the speed of the rotor by varying the pitch of the blades. If the wind reaches storm force, about 25 metres per second, the computer closes down the turbine to prevent damage.

Vocabulary

III. Remember these words:

access, to pollute, maintenance, blade, hub, to attach, shaft, to measure, wing, nacelle, gearbox, pipe, brake, emergency, grid, damage.

3. Insert the appropriate word.

Cause make prevent

1. The wind __________ the blades rotate.

2. The controller _________ the wind turbine from operating in a strong wind.

3. The blades ___________ the low-speed shaft to rotate.

V. Put the sentences in the correct order to describe the operation of the turbine.

a. The computer uses the yaw drive to turn the turbine into the most effective position.___

b. The gearbox increases the speed of the rotor shaft by 50 times. ___

c. The high-speed shaft drives the electric generator.___

d. The wind strikes the blades which turn the low- speed shaft.___

e. The power is sent by cable to the national grid.___

f. The generator converts the mechanical energy into electrical power.___

g. The anemometer and wind vane determine the wind speed and direction and transmit this to the computer. __

h. The computer starts the turbine when wind speed reaches 5 m/s.__