Explain how a coal-fired power station and a wind farm each produce electricity, and state one difference between them in terms of whether the energy resource is renewable or non-renewable.

OCR GCSE Physics A: Gateway Science (J249) — P6.2 Producing electricity · Explain · 4 marks · View as Markdown

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

A national energy report compares coal-fired power stations with wind farms as methods of generating electricity for the National Grid.

Model answer (4 marks)

In a coal‑fired power station coal is burned, producing thermal energy that heats water to form steam. The high‑pressure steam drives a turbine, which is connected to a generator that produces electricity.

In a wind farm the wind turns the blades of a turbine. The turbine’s rotation drives a generator, which produces electricity.

One key difference is that coal is a non‑renewable resource, whereas wind is renewable.

Examiner tips

  • Use the word ‘burns’ or ‘combustion’ for coal, ‘heats water’ and ‘steam’ for the turbine. Mention ‘generator’ in both cases. State the renewable/non‑renewable contrast explicitly. Keep the answer concise and to the point.

Common mistakes

  • Confusing the order of steps (e.g. saying the turbine produces steam).
  • Omitting the generator in either description.
  • Not stating the renewable/non‑renewable difference.

Mark scheme (4 marks)

  1. In a coal-fired power station, combustion of coal produces thermal energy (which heats water to produce steam).
  2. The steam (or thermal energy) turns turbines which drive generators to produce electricity.
  3. Wind directly turns turbines (which drive generators to produce electricity), with no combustion or steam required.
  4. Coal is a non-renewable energy resource whereas wind is a renewable energy resource.

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