Questions on Energy Sources
Q11. The tides can be used to generate electricity. A dam is built across a river estuary, as shown below.
![](pic11.png)
(a) The water is higher on one side of the dam than on the other. As the water begins to flow through the dam it turns a turbine. The turbine generates electricity. Describe the useful energy changes which take place in this process.
- Gravitational .potential energy in the water to kinetic energy in the water
![](../../../../graphics/symbols/nuclides/ticksmall.png)
- Kinetic energy in the water to kinetic energy in the turbine
![](../../../../graphics/symbols/nuclides/ticksmall.png)
- Kinetic energy in the turbine to kinetic energy in the generator
![](../../../../graphics/symbols/nuclides/ticksmall.png)
- Kinetic energy in the generator to electrical energy
![](../../../../graphics/symbols/nuclides/ticksmall.png)
MAX 2 marks
(b) Explain why tides are classified as a renewable energy source.
Tides are classified as a renewable energy source because the Moon's gravitational pull on the oceans is always there and follows a regular pattern of pull that we can use.![](../../../../graphics/symbols/nuclides/ticksmall.png)
1 mark
(c) Give one way, other than from the tides, of generating electricity by using the sea.
Wave power
accept ‘Ocean Thermal Energy Conversion’ or ‘OTEC’
1 mark
(d) Apart from cost, give one advantage and one disadvantage of an oil-fired power station compared with a tidal power station.
Advantage
An oil fired power station's output is easier to control than a tidal power station - it can be turned on when it is needed whereas the tides only give power at certain times. ![](../../../../graphics/symbols/nuclides/ticksmall.png)
You can build an oil-fired power station anywhere nut a tidal power station can only be built in a tidal estuary. ![](../../../../graphics/symbols/nuclides/ticksmall.png)
Disadvantage
Oil is non-renewable - it therefore will run out, whereas tidal power is renewable. ![](../../../../graphics/symbols/nuclides/ticksmall.png)
Oil causes pollution when burnt and it gives out greenhouse gases. It can also can cause pollution by oil spills. Tidal power stations cause hardly any pollution in comparrison. ![](../../../../graphics/symbols/nuclides/ticksmall.png)
One mark for advantage and one for disadvantage.
2 marks
Maximum 6 marks