Energy Resources and Electricity Generation
6 marks · NormalWind farms and nuclear power stations are both used to generate electricity in different countries.
Describe the energy transfers involved in generating electricity using a wind turbine.
Nuclear power stations can provide 'clean' energy but have some disadvantages.
State two disadvantages of nuclear power stations when compared to wind farms.
Explain, with reference to supply and demand, why a country cannot rely entirely on wind power to meet its electricity needs.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
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(a) Kinetic energy of moving air (wind) turns the blades of the turbine; this kinetic energy is transferred to the generator where it is converted to electrical energy.
(b) Produces dangerous radioactive waste; accident risk or risk of radiation release; very expensive to build and decommission; problem of waste disposal (any two).
(c) Wind is not always available—there are periods with little or no wind, meaning wind farms cannot supply electricity continuously; electricity demand varies, and wind cannot be relied on to match these changes; backup or other power sources are required.
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Identifies kinetic energy of wind turning turbine blades.
B2 (a) · 1 mark · Identifies transfer to electrical energy by the generator.
B3 (b) · 1 mark · Any one valid disadvantage of nuclear power stations (e.g., radioactive waste or accident risk).
B4 (b) · 1 mark · A second valid disadvantage distinct from the first (e.g., high cost, waste disposal problem).
E1 (c) · 1 mark · Explains that wind is unreliable or not constant (availability problem).
E2 (c) · 1 mark · Explains why supply cannot meet changing demand (e.g. cannot respond quickly; backup needed).
Worked solution
a) The kinetic energy of the wind turns the blades of the wind turbine. This kinetic energy is transferred, through the shaft, to the generator, which converts it into electrical energy.
b) Two disadvantages of nuclear power stations when compared to wind farms are: - They produce radioactive waste, which is hazardous for thousands of years. - Nuclear power stations are expensive to build and decommission, and there is a risk of radiation accidents.
c) Wind power cannot be relied on entirely because wind does not blow consistently. When there is little or no wind, wind farms generate little or no electricity. Furthermore, electricity demand varies throughout the day and year, but wind cannot be controlled to match these changes. Other power stations must be available to meet demand when wind supply is insufficient.