Renewable and Non-Renewable Energy Resources for Electricity — Answers
Answer sheet with model answers and success criteria for the Year 8 energy, light, sound & electricity worksheet.
Success TutoringWorksheetsAnswer sheetYear 8 · Science · Energy, Light, Sound & ElectricityRenewable and Non-Renewable Energy Resources for Electricity — Answers
Part A: Types of energy resources
Non-renewable resources will run out because they took millions of years to form or exist in a limited amount. They include the fossil fuels (coal, oil and natural gas) and nuclear fuels such as uranium.
Renewable resources are naturally replaced: sunlight (solar), wind, moving water (hydroelectric, tidal and wave), heat from inside Earth (geothermal) and biomass (plant and animal material).
- Coal
- Wind
- Uranium
- Natural gas
- Geothermal
- Sunlight
- Renewable
- Non-renewable (fossil fuel)
- Renewable
- Renewable
- Non-renewable (fossil fuel)
- Non-renewable (nuclear fuel)
Answer: Coal → Non-renewable (fossil fuel); Wind → Renewable; Uranium → Non-renewable (nuclear fuel); Natural gas → Non-renewable (fossil fuel); Geothermal → Renewable; Sunlight → Renewable
Answer: A renewable resource is replaced naturally as fast as we use it (or will not run out), such as wind or sunlight. A non-renewable resource is used much faster than it can form, so it will eventually run out, such as coal or uranium.
- Athe remains of plants and animals buried and compressed over millions of years
- Bvolcanic lava that cooled quickly
- Crainwater trapped underground
- Drocks heated by the Sun
Answer: the remains of plants and animals buried and compressed over millions of years
Coal formed from ancient plants; oil and natural gas mostly from tiny sea organisms.
Answer: True
The new plants take in carbon dioxide as they grow, and the supply can be replaced within a human lifetime.
Part B: Generating electricity
Most power stations work the same way: something makes a turbine spin, and the turbine turns a generator, where a magnet rotates near coils of wire to produce electricity. In coal, gas and nuclear power stations, heat boils water into high-pressure steam, which spins the turbine.
Answer: Chemical energy (coal) → thermal energy (burning heats water into steam) → kinetic energy (steam spins the turbine) → electrical energy (generator).
- AWind
- BHydroelectric
- CSolar photovoltaic (solar panels)
- DNatural gas
Answer: Solar photovoltaic (solar panels)
Solar cells convert light energy directly into electrical energy. The other resources all spin a turbine connected to a generator.
- ATidal
- BBiomass
- CGeothermal
- DHydroelectric
Answer: Geothermal
Geothermal power stations use hot water or steam from underground to spin turbines.
Answer: Wind turbines are turned by moving air (kinetic energy of the wind). Hydroelectric turbines are turned by falling or flowing water (gravitational potential energy of stored water changed to kinetic energy).
Part C: Interpreting the data
A region's electricity generation for one year came from: coal 30%, natural gas 18%, wind 20%, solar 16%, hydroelectric 12% and other sources 4%.
Answer: 48%
- Renewable = wind + solar + hydro
- 20 + 16 + 12 = 48%
Answer: 48%
- Fossil fuels = coal + natural gas
- 30 + 18 = 48%
Answer: 40 000 MWh
- 16% of 250 000
- 0.16 × 250 000 = 40 000 MWh
Answer: Maximum 150 MW; average 52.5 MW
- Maximum = 50 × 3 = 150 MW
- Average = 35% of 150 = 0.35 × 150 = 52.5 MW
Part D: Evaluate
- AThey release large amounts of carbon dioxide
- BTheir output changes with the weather and time of day
- CTheir fuel will run out
- DThey produce radioactive waste
Answer: Their output changes with the weather and time of day
Solar panels produce nothing at night and wind turbines need wind, so storage (such as batteries) or backup supply is needed.
Answer: Advantage (any one): reliable supply day and night; can be increased to meet demand; existing power stations are already built. Disadvantage (any one): releases carbon dioxide, which contributes to climate change; causes air pollution; coal is non-renewable; mining damages land.
Model answer: A natural gas power station is reliable: it can run day and night and its output can be increased quickly when demand is high. However, burning gas releases carbon dioxide, a greenhouse gas, and natural gas is non-renewable, so supplies will eventually run out and fuel must be bought for as long as the station runs. A solar farm produces no carbon dioxide while operating and its energy source will not run out, but it produces no electricity at night and less on cloudy days. The battery stores energy produced during the day for use at night, which improves reliability, although batteries are expensive and have limited capacity. I recommend the solar farm with a battery, because it provides a long-term, low-emission supply, with the battery reducing the problem of changing output.
Success criteria:
- Discusses the reliability of both options
- Discusses environmental impact, including carbon dioxide emissions
- Discusses renewable versus non-renewable supply
- Explains the role of the battery
- Gives a recommendation supported by the evaluation
Marking tips
- Give credit for correct method even when the final answer slips — the working shows where the thinking went right.
- For open-ended tasks, use the success criteria as a checklist rather than looking for one "right" answer.
- Celebrate what went well first, then pick one thing to work on next.