Energy Resources and Electricity Generation
4 marks · EasyTo cope with a sudden cold snap, a country's electricity demand rises quickly in one evening.
Name one type of power station that can respond quickly to sudden changes in demand, and one type that cannot.
Explain with reasons why the two types of power station you named in part (a) have these responses to demand.
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(a) Hydroelectric or gas-fired power stations respond quickly; nuclear cannot respond quickly. · must show one that can respond quickly, one that cannot
(b) Hydroelectric power stations respond quickly because they can release water from reservoirs instantly to generate power. Nuclear power stations cannot start up quickly; it takes a long time to begin the nuclear reactions and heat the reactor core. · must show reason for fast response (immediate release/use of energy), reason for slow response (delayed process/startup)
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Marking points
B1 (a) · 1 mark · Correctly identifies a power station type that responds quickly (hydroelectric or gas-fired).
B2 (a) · 1 mark · Correctly identifies a type that cannot respond quickly (e.g., nuclear, coal-fired).
B3 (b) · 1 mark · Gives a reason for fast response (e.g., hydroelectric: water can be released instantly; gas: quick startup).
B4 (b) · 1 mark · Gives a reason for slow response (e.g., nuclear: long process to heat and start; coal: slow to heat boilers).
Worked solution
a) Hydroelectric or gas-fired power stations can respond quickly. Nuclear power stations cannot respond quickly.
b) Hydroelectric power stations can quickly release water to drive turbines. Nuclear stations must heat the reactor, a slow process, so cannot respond quickly.