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Primary General Studies: Renewable Energy (Paper 3 (challenge))
Primary General Studies: Renewable Energy (Paper 3 (challenge))
Paper three combines policy tools, storage and engineering sums, covering cost, payback, reservoir potential energy and capacity, and ends with life-cycle costs.
Direct answers List every known value in consistent units, write the formula before substituting, then use an estimate to check the order of magnitude.
01 Paper details (check answers afterwards)
| Item | Detail |
|---|---|
| Questions | 10 |
| Suggested time | 20 |
| Difficulty mix | Foundation 3 · Intermediate 3 · Challenge 3 · Error redo 1 |
| Chapter | Chapter: Primary General Studies: Renewable Energy |
| Level | parts of a closed circuit, conductors against insulators, series against parallel, adding up battery voltage, and electrical safety |
02 Questions (10 items)
- FoundationWhat is the biggest technical challenge of renewable generation?
- FoundationWhat is the purpose of a feed-in tariff?
- FoundationHow does a pumped storage plant store electricity?
- IntermediateThirty 400 W panels cost 8 000 per kW to install, each kW makes 1 300 kWh a year and electricity costs 1.2 per kWh. What is the payback period?
- IntermediateA thousand homes each use 12 kWh a day. If solar supplies it all with 5 effective sun hours, what capacity is needed?
- IntermediateIf the rotor diameter of a wind turbine doubles, by what factor does the swept area change?
- ChallengeA reservoir releases 500 000 m³ of water through a 100 m drop, with density 1 000 kg/m³ and g of 9.81 m/s². What total potential energy is available in kWh?
- ChallengeWith an overall efficiency of 85 per cent in the same plant, what is the real output?
- ChallengeA region lifts its renewable share from 0.5 per cent to 7.5 per cent. How many times the original share is that?
- Error redoA classmate says renewables are always pollution free, so manufacturing does not matter. What is wrong?
03 Answers and one-line notes
| # | Answer | One-line note |
|---|---|---|
| 1 | Output varies with weather and time, so supply is unstable and needs storage or grid balancing. | Solar and wind are intermittent, and peak demand rarely matches peak output, so storage, standby plant and grid control are needed. |
| 2 | It buys renewable electricity at a rate above the normal tariff, encouraging homes and firms to install systems. | A feed-in tariff lets owners recover their costs and is a main policy tool for rooftop solar and small wind. |
| 3 | Spare electricity pumps water to an upper reservoir, and releasing it later generates power, turning electricity into potential energy and back. | Pumped storage acts as a very large battery that responds quickly, though some energy is lost in each conversion. |
| 4 | About 5.1 years. | Capacity is 12 kW, cost 96 000, yearly output 15 600 kWh saves 18 720, and 96 000 divided by 18 720 is about 5.1 years. |
| 5 | 2 400 kW is needed. | Daily demand is 12 000 kWh, and dividing by 5 hours gives 2 400 kW, before any allowance for storage and standby. |
| 6 | About 4 times. | Area varies with the square of the diameter, and 2 squared is 4, so available power at the same wind speed also rises about fourfold. |
| 7 | About 136 250 kWh. | Mass times g times height gives joules, and dividing by 3 600 000 gives 136 250 kWh. |
| 8 | About 115 812.5 kWh. | 136 250 times 0.85 is 115 812.5 kWh, and the rest is lost in the turbine and waterways. |
| 9 | 15 times the original. | 7.5 divided by 0.5 is 15, so the rise is 7 percentage points but 15 times the original level. |
| 10 | Making, moving and disposing of equipment uses energy and creates waste, so the whole life cycle must be compared. | Panels contain heavy metals and blades are hard to recycle, so the judgement must include total emissions and waste, not just running emissions. |
04 What to do after marking
- After marking, redo only the wrong items and write down which step went wrong (formula, unit, or misread number).
- Repeat the same item two days later; move to the next paper only when both attempts are correct.
- Parents only need the answer and note columns; there is no need to explain every item.
Paper four clears the conductor, insulator and battery direction misconceptions.Tutor Registration →
Questions and answers are written originally by the TutorZone team and are not taken from any school, publisher or examination authority paper. Every value is checked by computer.