# A hydroelectric power (HEP) station is built in a mountainous region where a large reservoir stores water at a high elevation. Describe the sequence of energy transfers that occur from the stored water until electrical energy is produced, and state one advantage and one disadvantage of using hydroelectricity compared with burning fossil fuels.

> Pearson Edexcel International GCSE Physics (4PH1) — 4.3 Energy resources and electricity generation · Describe · 4 marks

> Water stored at a high elevation in a reservoir is released and flows down through pipes to drive turbines connected to generators at the base of a dam.

## Mark scheme (4 marks)

1. Gravitational potential energy (GPE) of the stored water is transferred to kinetic energy as the water flows down
2. Kinetic energy of the moving water turns the turbine, which drives the generator to produce electrical energy
3. One advantage: hydroelectricity is a renewable energy resource / does not release greenhouse gases / does not contribute to global warming / no fuel costs once built
4. One disadvantage: hydroelectricity is less reliable / depends on rainfall levels / flooding of land to create reservoir causes habitat destruction / high initial construction cost

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