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GCSE Questions: Energy Sources

Q14. The photo shows a solar thermal power station that has been built in a hot desert.

The power station uses energy from the Sun to heat water to generate electricity.

Energy from the Sun is reflected towards a solar receiver using many mirrors.

(a)

(i) Which part of the electromagnetic spectrum provides most of the energy to heat the water in a solar thermal power station?

[1 mark]

(ii) Describe how heated water is used to generate electricity by this solar thermal power station. The process is the same as in a fossil fuel power station.

[3 marks]

(b) A new type of solar power station, called a solar storage power station, is able to store energy from the Sun by heating molten chemical salts. The stored energy can be used to generate electricity at night.

(i) It is important that the molten chemical salts have a high specific heat capacity. Suggest one reason why.

[1 mark]

(ii) The solar storage power station can store a maximum of 2 200 000 kWh of energy. The solar storage power station can supply a town with a maximum electrical power of 140 000 kW.

Calculate for how many hours the energy stored by the solar storage power station can supply the town with electrical power.

Give your answer to 2 significant figures.

[3 marks]

(iii) The table below gives information about the place where the solar storage power station has been built.

Season Mean number of daylight hours Mean power received from the Sun per square metre in kW
Spring
11.5
0.90
Summer
13.5
1.10
Autumn
12.0
0.95
Winter
10.5
0.71

 

The solar storage power station does not operate at the maximum possible electrical output every day of the year.

Suggest why.

[2 marks]

(c) Power stations do not work at maximum possible electrical output all the time.

The 'capacity factor' of a power station is calculated using the equation:

Capacity factor = (actual electrical output per year)/ (maximum possible electrical output per year)

The table below shows capacity factors for different types of power station.

Type of power station
Does it use a renewable energy source
Capacity factor
Coal
No
0.41
Natural gas
No
0.48
Nuclear
No
0.66
Solar thermal
Yes
0.33
Tidal
Yes
0.26
Wind turbine
Yes
0.30

(i) Compare the capacity factors of the renewable power stations with those of the non-renewable power stations in the table.

Explain the reason for the difference between the capacity factors.

[3 marks]

(ii) The capacity factor of a solar storage power station is higher than for all other renewable power stations. Suggest one reason why.

[1 mark]

(Total 14 marks)