Week 20 · Theme 3, Unit 3 Energy and Fuels, Concept 3.3 Renewable Energy Resources (A) · 3 lessons
3
Catching the wind
Discovery Education Science P4: Term 2, Unit 3, pp. 56–69
GoalExplain how a wind turbine makes electricity, draw its energy chain and decide where wind turbines work best.
New words
wind turbine · a tall machine whose blades are turned by wind to drive a generatorwind farm · many wind turbines in one placeblade · one of the long, thin arms of a turbine that catches the wind
Explanation
Wind is moving air, so it has kinetic energy. The Sun warms different parts of the Earth by different amounts, and this makes the air move. A wind turbine catches this energy. The moving air pushes the blades, which turn. The turning blades spin a generator, which makes electrical energy. Big cables carry the electricity to where it is needed. The energy chain is: the Sun warms the Earth, wind moves, blades turn, the generator makes electricity, and power lines carry it to a home. A wind turbine gives out no smoke. Wind turbines work best where the wind is strong and steady: on coasts, open plains and hills. A group of turbines is a wind farm. Egypt has wind farms near the Gulf of Suez, where it is often windy.
Sun warms Earth→wind blows→blades turn→generator makes electricity→power lines to homes
Worked examples
Youssef holds a toy pinwheel in front of a small fan that a grown-up switches on. With a weak breeze it turns 4 times in 10 seconds; with a strong breeze 12 times. The stronger wind gave 12 − 4 = 8 more turns.
Place
Wind
Good for turbines?
sheltered valley
little
no
open plain by the sea
most days
yes
A town has two possible places for turbines: a sheltered valley with little wind and an open plain by the sea where the wind blows most days. The plain by the sea is the better place.
wind: motion→blades: motion→generator: electrical
Energy chain for one turbine: kinetic energy of the wind, then kinetic energy of the blades, then electrical energy from the generator. Some energy also leaves as sound and heat.
Class activity
Catch the wind. A grown-up helps. Hold a toy pinwheel outdoors in a breeze or in front of a small fan. Count how many times one coloured blade passes the top in 10 seconds, using a clock. Try in the shade, and in a more open place. Where did it turn most? Never fly a kite near power lines.
Practice
1
What makes the blades of a wind turbine turn?
The moving air (wind) pushes them.
2
What does the generator in a wind turbine make?
Electrical energy.
3
Which place is best for a wind farm? Say the letter.
Letter
Place
A
deep sheltered valley
B
open coast
B: the open coast, because the wind is strong and steady.
4
A pinwheel turns 3 times in 10 s in light wind and 9 times in strong wind. How many more turns in strong wind?
