Question Constellation Sign up for free AQA · GCSE · Physics · Higher
Comparing Energy Storage Methods
| Method | Energy stored per 100 kg of water in kJ | Percentage of stored energy wasted | Installation |
|---|---|---|---|
| A: Increasing water temperature by 80 °C | 33 600 | 40% | Anywhere |
| B: Pumping water uphill to a height of 500 m | 490 | 25% | High mountains |
Compare the advantages and disadvantages of the two methods of storing energy.
Include calculations in your answer.
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Marking points
- 1 Addresses advantages and disadvantages of both Method A and Method B.
- 2 Includes at least one relevant calculation from the table data.
- 3 Uses the calculation and source data to make a clear comparison between the methods.
Full-mark answer
Method A can be installed anywhere and stores far more energy per 100 kg of water. Its useful energy is 0.60 × 33 600 = 20 160 kJ, so 13 440 kJ is wasted. However, the hot water would need insulating. Method B wastes only 25%, so it is more efficient: its useful energy is 0.75 × 490 = 367.5 kJ and 122.5 kJ is wasted. Its disadvantage is that it needs a suitable high-mountain location. Therefore A stores much more useful energy and is easier to site, whereas B is more efficient.
Why this answer loses marks
Method A is better because it stores more energy.
This uses only one advantage. Compare both methods, include a relevant calculation, and make the trade-off clear.