A coastal town is planning to install a tidal energy power station to generate electricity. Describe the energy transfers that take place from the water to the electrical energy output, and state one advantage and one disadvantage of using tidal energy compared to burning fossil fuels.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Tidal power stations use the movement of seawater driven by the gravitational pull of the Moon to generate electricity. The rising and falling tides cause water to flow through turbines.
Model answer (4 marks)
The moving water has kinetic energy, which drives the turbines. The kinetic energy of the turbine is transferred to electrical energy by the generator.
Advantage: tidal energy is a renewable resource and does not produce greenhouse gases.
Disadvantage: tidal energy is less reliable, as it only generates electricity when tides are flowing.
Advantage: tidal energy is a renewable resource and does not produce greenhouse gases.
Disadvantage: tidal energy is less reliable, as it only generates electricity when tides are flowing.
Examiner tips
- Use the word "kinetic" for the water and turbine, "electrical" for the generator output.
- Mention the renewable nature and lack of CO₂ for the advantage.
- State the tidal cycle limitation for the disadvantage.
Common mistakes
- Confusing kinetic energy with potential energy of the water.
- Using vague terms like "clean" instead of "renewable" and "no greenhouse gases”.
- Omitting the specific cause of the disadvantage (tidal cycle) or giving a generic cost issue.
Mark scheme (4 marks)
- The moving water has kinetic energy (which drives the turbines) / gravitational potential energy of water is converted to kinetic energy
- Kinetic energy of the turbine is transferred to electrical energy (by the generator)
- One advantage: tidal energy is a renewable resource / will not run out / does not produce greenhouse gases / does not cause global warming
- One disadvantage: tidal energy is less reliable / only generates electricity when tides are flowing / is dependent on tidal cycles; OR the construction cost is higher than fossil fuel power stations
Key terms in this question
Related
- All Pearson Edexcel International GCSE Physics (4PH1) revision notes →
- How to answer a "Describe" question →
- Decode the mark scheme abbreviations →
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