Supply and demand
3 marks · NormalA popular sport event ends on TV, and millions of people immediately turn on their electric kettles to make a drink.
Explain how electricity suppliers ensure that the extra demand can be met instantly. In your answer, refer to the types of power stations involved.
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Show answer
Electricity suppliers use power stations that can quickly increase output to meet sudden demand. These include gas-fired and hydroelectric power stations, which can be switched on rapidly. Hydroelectric stations release stored water, while gas turbines can start producing power within minutes.
Must show: naming rapid response stations, explaining mechanism
Common mistakes: Mentioning fossil fuel stations like coal or nuclear as the main solution
Show mark scheme and worked solution
Marking points
B1 · 1 mark · Mentions gas-fired and/or hydroelectric stations as rapid responders
B1 · 1 mark · Explains how rapid start is possible (turbines switched on, water released)
B1 · 1 mark · Relates this to meeting unpredictable, sudden demand
Worked solution
Suppliers use hydroelectric stations to release water instantly and gas-fired power stations to start turbines within minutes so that the extra demand from many people using kettles is met immediately.