A tidal barrage uses the movement of seawater to generate electricity. Explain how the energy of moving seawater is converted into electrical energy in a tidal barrage power station, and state whether tidal energy is a renewable or non-renewable energy resource.

WJEC GCSE Physics (Wales) — 1.2 Generating electricity · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

A tidal barrage is built across a river estuary. As the tide comes in and goes out, seawater flows through tunnels in the barrage, generating electricity.

Model answer (4 marks)

The kinetic energy of the moving seawater turns a turbine.
The turbine drives a generator.
The generator converts the mechanical energy into electrical energy.
Tidal energy is a renewable resource because it can be replenished while it is being used.

Examiner tips

  • Use the exact sequence: kinetic energy → turbine → generator → electricity.
  • Mention that tidal energy is renewable.
  • Keep the answer concise and to the point.
  • Use UK spelling (e.g., ‘generator’).

Common mistakes

  • Confusing kinetic energy with potential energy of the water.
  • Failing to state that tidal energy is renewable.
  • Writing a long paragraph instead of short, clear points.

Mark scheme (4 marks)

  1. The kinetic energy of the moving seawater turns a turbine
  2. The turbine drives/turns a generator
  3. The generator produces/generates electricity (transfers kinetic energy to electrical energy)
  4. Tidal energy is a renewable energy resource because it can be replenished whilst it is being used

Key terms in this question

renewable energy resource

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