الأسبوع 21 · المحور الثالث «حماية كوكبنا»، الوحدة الثالثة «الموارد الموجودة على سطح الأرض»، المفهوم 3.3 «حماية الموارد الموجودة على سطح الأرض» (ب): الهواء والماء النظيف · 3 دروس
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Cleaner air from wind and sun
Discovery Education Science P5: Term 2, Unit 3, pp. 67–68
GoalExplain why burning fuels pollutes the air and name renewable sources of energy that pollute less.
New words
fossil fuel · oil, gas or coal, which formed from living things over millions of years and is burned for energyair pollution · harmful smoke, dust and gases in the airrenewable energy · energy from a source that does not run out, such as wind, sunlight and running waterbiofuel · fuel made from plants or plant waste
Explanation
Most of the energy we use for cars, factories and power stations comes from burning fossil fuels. Burning makes smoke and gases that spread through the air and make it harder and less healthy to breathe. Air is a natural resource too, so we want to keep it clean. One good answer is to make electricity in ways that burn nothing. A wind turbine is turned by the moving air. A solar panel changes sunlight into electricity. Running water that falls through a dam can turn machines as well. Egypt already uses all three: wind farms near Zafarana by the Gulf of Suez, solar parks such as Benban near Aswan, and electricity from the Aswan High Dam. Biofuel is made from plants or plant waste and can pollute less than oil, but it needs land and care. No source is perfect: wind needs wind, solar panels stop at night, and dams change a river. Still, they are much kinder to the air than fossil fuels.
On the road to the Red Sea, Omar’s family passes a row of tall wind turbines. The wind turns the blades, the blades turn a generator, and the generator makes electricity. Nothing is burned, so no smoke goes into the air.
A bus and a solar panel both help a town. The bus burns fuel to move people and puts gases into the air. The panel lets the Sun’s light make electricity for a school and puts none.
Source
A limit
wind
needs wind
solar
not at night
dam
changes a river
Marwan says, “Renewable energy has no problems at all.” Mariam disagrees. A solar park needs lots of land and gives no electricity at night, and a dam changes the river. Renewable sources are kinder to the air, but they still have limits.
Class activity
Pinwheel wind test (outdoors, a grown-up helps). A grown-up makes a paper pinwheel and fixes it to a straw with a paper fastener, with no sharp pins. Hold it in the wind, or blow gently from a metre away, and count how many full turns it makes in 10 seconds. Try three times in a breezy place and three times in a sheltered place, and write the counts in a table. Which place turns it more? Say what that tells you about where to put a wind turbine.
Practice
1
Why does burning fossil fuels harm the air?
It makes smoke and gases that spread in the air and make it less healthy to breathe.
2
Put the steps in order: A generator makes electricity, B wind blows, C blades turn.
?→?→?
B, C, A: the wind blows, the blades turn, the generator makes electricity.
3
Which pictures show a way to make electricity without burning fuel? Say the letters.
A and C: the wind and the Sun. The car burns fuel.
4
Give one limit of solar panels and one of wind turbines.
Solar panels do not work at night; wind turbines need wind.
