What does non-renewable mean?
This content is examined in Paper 2 only.
You already know how fossil fuel and nuclear power stations generate electricity. This lesson judges them: the good and bad points of using each one on a large scale, to supply whole towns and cities.
Coal, oil and natural gas took millions of years to form underground. We burn them far faster than new ones can form. Uranium, the usual nuclear fuel, is a metal dug out of the ground, and no more of it is being made. So fossil fuels and nuclear fuel are both non-renewable. The Earth has a fixed supply of them, and one day that supply will be used up.
Key terms:
- Non-renewable energy resource: an energy resource that will run out one day, because it is not replaced as it is used.
- Global warming: the rise in the average temperature of the Earth's atmosphere.
- Acid rain: rain made acidic by gases such as sulfur dioxide dissolving in the water in clouds.
- Demand: the amount of electricity that people are using at a given moment.
- Decommissioning: safely shutting down and taking apart a power station at the end of its life.
Fossil fuels: coal, oil and natural gas
✅ Advantages
Reliable. Fuel can be burned at any time, day or night, in any weather.
Large output. One power station can supply a whole city, and it takes up much less land than a wind farm or solar farm with the same output.
Can meet demand. The output can be turned up when demand rises and turned down when it falls. Gas power stations can be started up especially quickly.
Easy to site. Fuel can be delivered by pipe, train or ship, so the power station does not need mountains, a coast or a sunny climate.
❌ Disadvantages
Carbon dioxide. Burning any fossil fuel releases carbon dioxide into the atmosphere. Carbon dioxide traps energy in the atmosphere, so it adds to global warming.
Sulfur dioxide. Coal and oil contain some sulfur. When they burn, sulfur dioxide is released, which causes acid rain. Acid rain damages trees, kills fish in lakes and wears away stone buildings.
They will run out. They are non-renewable.
Fuel costs. Fuel has to be bought for as long as the power station runs. Mining coal and drilling for oil also damage the landscape, and oil spilt at sea harms wildlife.
The three fossil fuels are not equally polluting. For the same amount of electricity generated, natural gas releases the least carbon dioxide of the three, and almost no sulfur dioxide. Coal releases the most, and oil is in between.
Nuclear power
✅ Advantages
No carbon dioxide while running. Nothing is burned, so a working nuclear power station does not add to global warming. It releases no sulfur dioxide either, so it does not cause acid rain.
A huge amount of energy from a little fuel. A small mass of nuclear fuel releases far more energy than the same mass of coal, so little fuel has to be mined and transported.
Reliable, with a large output. It generates electricity day and night, in all weathers.
❌ Disadvantages
Radioactive waste. The used fuel is radioactive and stays dangerous for thousands of years. It must be stored very safely, which is difficult and expensive.
Expensive to build and to decommission. Building takes many years. At the end of its life, the radioactive parts must be taken apart with great care, which also takes many years.
Risk of accidents. Accidents are rare, but a serious one can release radioactive material over a wide area, as happened at Chernobyl in 1986 and Fukushima in 2011.
Slow to change. A nuclear power station takes a long time to start up, so it cannot follow quick changes in demand. The fuel is also non-renewable.
The comparison table
| Feature | Fossil fuels | Nuclear |
|---|
| Reliable? | Yes | Yes |
| Output | Large | Large |
| Follows changes in demand? | Yes, gas most quickly | No, slow to start up |
| Carbon dioxide while running | Yes: adds to global warming | None |
| Sulfur dioxide | Yes from coal and oil: acid rain | None |
| Waste | Waste gases go into the air | Radioactive waste, dangerous for thousands of years |
| Cost | Cheaper to build, but fuel must be bought all the time | Very expensive to build and to decommission |
| Will it run out? | Yes | Yes |
Renewable or non-renewable?
An exam question may describe a place and ask you to choose. Use what you learnt in Comparing Renewable Energy Resources, then ask three questions.
- Does the supply have to be reliable? A hospital or a large city needs electricity at every moment. Fossil fuels and nuclear power can give that. Wind and solar power cannot do it without a back-up.
- What does the place offer? Mountains and rain suit hydroelectric power. A flat, cloudy place with little wind has few renewable choices.
- What matters most to the people choosing? If the aim is to cut carbon dioxide, renewables or nuclear power fit. If the aim is a low building cost, a gas power station fits.
Many countries use a mixture: reliable power stations for the steady demand, and renewables whenever the wind blows or the Sun shines.
Worked example
A large city lies on flat land far from the sea. It is often cloudy and has light winds. Explain why a gas power station may be chosen instead of a solar farm.
Step 1, use the place: it is often cloudy, so solar cells would generate little electricity, and nothing at night.
Step 2, give the matching advantage: a gas power station is reliable. It generates electricity at any time and in any weather.
Step 3, add a second advantage: its output can be turned up quickly when the city's demand rises.
Step 4, be fair: the gas power station releases carbon dioxide, which adds to global warming, and gas will run out one day. An evaluate question would want this point too.
Common mistakes
- Writing that nuclear power stations release carbon dioxide or cause acid rain when they run. Nothing is burned, so they do neither.
- Calling nuclear power renewable because it is "clean". Uranium is not replaced, so it is non-renewable.
- Mixing up the two gases. Carbon dioxide goes with global warming. Sulfur dioxide goes with acid rain.
- Writing only "pollution" or "bad for the environment". Name the gas and its effect.
- Writing that nuclear power is "dangerous" with no detail. Say that the waste is radioactive for thousands of years, or that an accident could release radioactive material.
Exam-style question
A country generates most of its electricity in coal power stations. Its government plans to replace one old coal power station with a nuclear power station.
(a) State what is meant by a non-renewable energy resource. [1 mark]
(b) Explain how burning coal in a power station can lead to acid rain. [2 marks]
(c) Give two advantages that coal power stations and nuclear power stations share. [2 marks]
(d) Evaluate the government's plan to replace the coal power station with a nuclear power station. [5 marks]
Model answer
(a) A resource that will run out because it is not replaced as it is used. (1)
(b) Coal contains sulfur, so sulfur dioxide is released when it burns. (1) The sulfur dioxide dissolves in water in clouds and makes the rain acidic. (1)
(c) Both are reliable, as neither depends on the weather. (1) Both have a large output. (1)
(d) A nuclear power station releases no carbon dioxide while it runs, so the plan would cut the country's contribution to global warming. (1) It releases no sulfur dioxide, so there would be less acid rain. (1) However, it produces radioactive waste that stays dangerous for thousands of years and must be stored safely. (1) It is also very expensive to build and to decommission, and there is a small risk of an accident that releases radioactive material. (1) Conclusion: the plan is a good one if the country can pay for it and store the waste safely, because it keeps a reliable supply while removing the gases that cause global warming and acid rain. (1)
Exam tip
In part (d), compare the two power stations directly: say what the nuclear power station does better than coal and what it does worse. Both are reliable, so reliability alone cannot decide between them. Finish with a clear conclusion and the reason for it.