Course: Combined Science + Separate Physics | Tier: Foundation + Higher | Read the notes, then try the questions on paper.
Notes
The main energy resources
Non-renewable (will run out): fossil fuels – coal, oil and gas – and nuclear fuel.
Renewable (replenished as they are used): bio-fuel, wind, hydro-electricity, geothermal, tides, solar and water waves.
We use energy resources for transport (mostly oil-based fuels), electricity generation and heating (mostly gas).
Reliability
- Reliable, available on demand: fossil fuels, nuclear, bio-fuel, geothermal.
- Hydro-electricity can be switched on very quickly to meet sudden rises in demand.
- Tides are predictable, but the output varies during the day.
- Unreliable: wind (no wind, or too strong), solar (night, cloud), waves (calm seas).
Environmental impact
- Fossil fuels: burning releases carbon dioxide (a greenhouse gas that contributes to global warming and climate change), sulfur dioxide (acid rain) and particulates. Extraction can damage habitats; oil spills.
- Nuclear: no carbon dioxide while generating, but produces radioactive waste that must be stored safely for a very long time, and there is a small risk of major accidents.
- Wind: no pollution when running, but turbines can be noisy and spoil the view.
- Hydro-electric dams and tidal barrages: flood valleys or estuaries, destroying habitats.
- Bio-fuels: the plants absorb carbon dioxide as they grow, but growing them uses land that could grow food, and forests may be cleared.
Trends and limits
Use of renewables is increasing to reduce carbon dioxide emissions. Change is limited by cost (building new power stations), reliability, public opinion (people may not want turbines nearby) and politics. Scientists can identify environmental problems, but they cannot always decide what action should be taken.
Questions
Q1 (F) What is a renewable energy resource?
Show answer
A resource that is being (or can be) replenished as it is used, so it will not run out.
Q2 (F) Name three renewable and two non-renewable energy resources.
Show answer
Renewable: any three of wind, solar, hydro-electricity, tides, waves, geothermal, bio-fuel. Non-renewable: any two of coal, oil, gas, nuclear fuel.
Q3 (F) Give two renewable resources that are unreliable, and explain why.
Show answer
Wind – the wind doesn’t always blow (or is too strong). Solar – no output at night and less when it’s cloudy. (Waves also: depends on the weather.)
Q4 (F) Why is burning fossil fuels harmful to the environment?
Show answer
It releases carbon dioxide, a greenhouse gas that contributes to global warming and climate change. It also releases sulfur dioxide, which causes acid rain.
Q5 (F) Give one advantage and one disadvantage of nuclear power.
Show answer
Advantage: reliable and releases no carbon dioxide while generating electricity. Disadvantage: produces radioactive waste that must be stored for a very long time (or: risk of a major accident).
Q6 (F/H) Why is tidal power more reliable than wind power?
Show answer
Tides happen every day at times that can be predicted, whereas the wind depends on the weather and can’t be relied on.
Q7 (F/H) Why is hydro-electricity useful when demand for electricity rises suddenly?
Show answer
It can be started up very quickly by releasing the stored water, unlike coal or nuclear power stations which take a long time to start.
Q8 (F/H) Suggest two reasons why fossil fuels are still widely used.
Show answer
Any two of: they are reliable and can meet demand at any time; power stations and vehicles already exist that use them; they release a lot of energy; building new renewable generation is expensive.
Q9 (H) Why are bio-fuels sometimes described as carbon neutral, and why is this not completely true?
Show answer
The plants absorb carbon dioxide as they grow, which balances the carbon dioxide released when the fuel is burned. But energy (often from fossil fuels) is used to farm, process and transport them, and land may be cleared to grow them.
Q10 (H) A town plans to replace its coal-fired power station with a wind farm. Evaluate this plan. (6 marks)
Show answer
For: wind is renewable and will not run out; no carbon dioxide or sulfur dioxide when generating, so less climate change and acid rain; no fuel costs.
Against: wind is unreliable, so electricity may not be available when needed – a backup is required; many turbines are needed to replace one power station, using a lot of land; noise and visual impact; high building cost.
Conclusion: give a judgement, e.g. a good plan if combined with a reliable backup such as hydro-electricity or the National Grid.
