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GCSE Questions: Energy Sources

Q28.

The photo shows a large wind farm off the coast of the UK.

The mean power output of the wind farm is 696 MW, which is enough power for 580 000 homes.

(a) Calculate the mean power needed for 1 home. Give your answer in watts.

696 MW = 696 000 000 W

power per home = 696 000 000/580 000 = 1 200 W

[2 marks]

(b) On one day the demand for electricity in the UK was 34 000 MW.

Suggest two reasons why wind power was not able to meet this demand.

Any two from:

wind power is unreliable - it may not have been windy enough on that day

wind turbines don't turn when the wind is too strong/weak

there are not enough wind turbines (in the UK)

some wind turbines may have been offline for maintenance

[2 marks]

(c) Some of the energy from the wind used to rotate a wind turbine is wasted.

An engineer oils the mechanical parts of a wind turbine.

Explain how oiling would affect the efficiency of the wind turbine.

The efficiency of the turbine would increase because the percentage/proportion/amount of energy that was usefully transferred would increase (or because the percentage/proportion/amount of energy wasted would decrease) because less work is done against friction.

[3 marks]

(d) In most homes in the UK there are many different electrical devices.

Explain why people should be encouraged to use energy efficient electrical devices.

More efficient devices waste less energy by needing a lower energy input for the same energy output. This would minimise the electricity/energy demand and minimise the environmental impact from (fossil fuel) electricity generation.

Just saying energy efficient electrical devices are ‘better for the environment’ or saying they ‘save energy’ got you no marks - you had to explain how they were better for the environment or saved energy by lowering demand.

[2 marks]

(Total 9 marks)