Renewable energy resources Cambridge IGCSE Environmental Management revision
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In plain words
The wind will blow tomorrow whether or not you used it today. That is the whole idea of a renewable resource: nature replaces it as fast as you take it. The catch is that nature does not always deliver when you want it.
9 things to know
- A renewable, or non-finite, energy resource is replaced naturally as fast as it is used, so it will not run out.
- Biofuels are fuels made from living material. Wood and other biomass are burned. Bioethanol is made by fermenting crops such as sugar cane. Biogas, mostly methane, is made when bacteria break down manure and plant waste without oxygen. Biofuels are burned to make steam, which turns a turbine.
- Geothermal power: water is pumped down to hot rocks underground. It returns as steam, which turns a turbine.
- Hydro-electric power: a dam holds a river back in a reservoir. Water released through the dam turns a turbine.
- Tidal power: turbines in a barrier across an estuary are turned as the tide flows in and out. Wave power: the up and down movement of waves drives a generator.
- Wind power: the wind turns the blades of a turbine, which turns a generator. Solar power: solar cells turn light straight into electricity.
- Benefits. Renewables do not run out, most release no carbon dioxide while they run, and with no fuel to buy they are cheap to run.
- Limitations. Wind and solar power are not reliable: no wind or no sun means no electricity. Dams flood land and move people. Tidal and geothermal power need the right site. Biofuel crops take land that could grow food.
- Wind turbines and solar farms take up space and change the look of the landscape, and turbines can kill birds. Every energy resource has some impact.
Worked example
An island has strong winds on most days and very little flat land. Discuss whether wind power would suit it.
- For: the wind is strong and regular, there is no fuel to import, and no carbon dioxide is released.
- Against: on calm days there is no electricity, so the island still needs storage or another supply.
- Turbines can stand in the sea, which saves the island's land, although building at sea costs more.
- Conclusion: wind power suits the island as its main supply, backed up by batteries or another source.
Tips and tricks
- Wind, wave, tidal and hydro-electric power turn the turbine directly. No steam is involved, so do not write about boiling water.
- Biofuels are renewable, but burning them does release carbon dioxide. The crop took in carbon dioxide while it grew, which is why they are called close to carbon neutral.
It lands in your notebook with its questions as flashcards.
Renewable energy resources: 6 questions and answers
These are the quiz’s questions. Do the quiz first, then come back here for the ones that got you.
Which of these is a renewable energy resource?
Heat from the rocks is not used up.
What is biogas mostly made of?
Bacteria make it from manure and plant waste, without oxygen.
Which resource generates electricity without turning a turbine?
Solar cells change light directly into electricity.
Which is a limitation of hydro-electric power?
A large area behind the dam goes under water.
Why is geothermal power not used everywhere?
It suits volcanic regions.
Which resource is the most predictable, years in advance?Stretch
Tides follow the Moon, so their times are known far ahead.
Quiz
6 questions
Tap an answer and you’ll see straight away whether it’s right, and why.
Worksheet
3 questions, 7 marks. Write your answers on paper, then check them.
Renewable energy resources
Cambridge IGCSE Environmental Management 0680 · 7 marks · papermunch.org
Name ______________________________ Date ______________
Describe how hydro-electric power is generated.[3]
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A dam holds water back in a reservoir. Water is released through the dam and turns a turbine. The turbine turns a generator, which produces electricity.
Explain why solar power is described as unreliable.[2]
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It generates only when the sun shines. There is no output at night and less on cloudy days, so supply may not match demand.
State two limitations of growing crops for biofuels.[2]
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Any two: land is used that could grow food; forest may be cleared to grow them; carbon dioxide is released when they burn; they need water and fertiliser.
Answers: Renewable energy resources
- 1. A dam holds water back in a reservoir. Water is released through the dam and turns a turbine. The turbine turns a generator, which produces electricity.
- 2. It generates only when the sun shines. There is no output at night and less on cloudy days, so supply may not match demand.
- 3. Any two: land is used that could grow food; forest may be cleared to grow them; carbon dioxide is released when they burn; they need water and fertiliser.