Energy Management
Primary 6 · Science and Elementary Technology
Energy Management
Lesson 4 of 6
15 min
Let's begin
Gatete's grandmother remembers when the hill behind their home was covered with tall trees. Many were cut down, year after year, for firewood and charcoal.
Gatete looks up at the sky. "Grandma, can the sun ever run out like the trees did?" Today you will find out which energy sources can run out, and which will keep coming back.
A renewable energy source is one that nature replaces quickly, so it will not run out if we use it wisely. Examples: solar, wind, hydropower, geothermal, biogas and biomass.
Be careful with firewood and charcoal: they are renewable only if new trees are planted as fast as old ones are cut. When we cut faster than we plant, forests disappear.
A non-renewable source took millions of years to form, or forms very slowly, so once we use it up it is gone. Examples: the fossil fuels (petroleum, coal and natural gas), peat, and uranium for nuclear power. The methane in Lake Kivu builds up very slowly, so it is used much faster than nature replaces it.
| Renewable | Non-renewable |
|---|---|
| Solar | Petroleum (petrol, diesel, kerosene) |
| Wind | Coal |
| Hydropower | Natural gas |
| Geothermal | Peat |
| Biogas | Uranium (nuclear) |
| Biomass (if trees are replanted) |
They will run out one day. Burning them gives off smoke and carbon dioxide, which pollute the air and warm the climate. Rwanda must buy petroleum from other countries, which is expensive.
You can speak up for clean energy: make a poster for your class, remind your family to plant trees at umuganda, and explain to friends why solar lamps and improved stoves are good choices.
Tip
RE-newable means it comes back again
The sun rises every day and the rains return every season. NON-renewable means once it is gone, it is gone.
Try each one on your own first, then tap Show answer to check.
Sort these into renewable and non-renewable: solar, petrol, wind, peat, hydropower, kerosene.
Answer: Renewable: solar, wind, hydropower. Non-renewable: petrol, peat, kerosene.
When is firewood a renewable source of energy?
Answer: Only when new trees are planted to replace the ones that are cut.
Give two advantages of solar energy.
Answer: Any two: it will not run out, it makes no smoke, sunlight is free, it can reach homes far from the grid.
Give one problem with hydropower during a long dry season.
Answer: Rivers carry less water, so less electricity can be made.
Keza says, "Petrol gives a lot of energy, so Rwanda should use only petrol." Do you agree? Explain.
Answer: No. Petrol is non-renewable and will run out, it pollutes the air, and Rwanda must import it at high cost. Renewable sources are cleaner and last.
What you learned today
Sources and credits
Quick check
Which of these is a renewable source of energy?
