Comparing Energy Resources — Renewable vs Non-Renewable

In this lesson you will learn how to compare and evaluate different energy resources, discuss their advantages and disadvantages, and apply your knowledge to real-world scenarios. This is part of AQA GCSE Combined Science Trilogy (8464), Section 6.1.

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Renewable vs Non-Renewable — Key Differences

Feature	Non-Renewable	Renewable
Supply	Finite — will run out	Will not run out
Replenishment	Takes millions of years	Replenished continuously or quickly
CO₂ emissions	Produce CO₂ (fossil fuels); nuclear does not	Little or no CO₂ during operation
Reliability	Can generate on demand (reliable)	Some are intermittent (wind, solar, wave)
Examples	Coal, oil, gas, nuclear	Wind, solar, hydro, tidal, wave, geothermal, biofuel

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Comparing Specific Resources

Comparison Table

Resource	Renewable?	Reliable?	CO₂ Emissions	Environmental Impact	Cost
Coal	No	Yes — on demand	High	Air pollution, mining damage	Moderate
Oil	No	Yes — on demand	High	Air pollution, oil spills	Moderate–high
Natural gas	No	Yes — on demand	Moderate (less CO₂ than coal)	Air pollution, fracking concerns	Moderate
Nuclear	No	Yes — continuous	None during generation	Radioactive waste, accident risk	High (build), low (run)
Wind	Yes	No — intermittent	None	Visual/noise, bird strikes	Low (run), moderate (build)
Solar PV	Yes	No — intermittent	None	Land use, manufacturing impact	Falling rapidly
Hydroelectric	Yes	Yes — on demand	None	Flooding, habitat loss	High (build), very low (run)
Tidal	Yes	Yes — predictable	None	Ecosystem disruption	Very high (build)
Wave	Yes	No — intermittent	None	Low impact, difficult maintenance	High
Geothermal	Yes	Yes — continuous	Very low	Limited locations	High (drill), low (run)
Biofuel	Yes	Yes — on demand	Carbon neutral (in theory)	Land use, deforestation risk	Variable

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Evaluating Energy Resources — A Structured Approach

When an exam question asks you to evaluate or compare energy resources, use this framework:

1. Environmental impact — CO₂ emissions, pollution, habitat destruction, waste.
2. Reliability — Can it generate on demand? Is it intermittent?
3. Cost — Capital cost (building) and running cost.
4. Availability — Is the resource available in the given location?
5. Scale — Can it meet large-scale demand?

graph TD
    A["Evaluate Energy Resource"] --> B["Environmental impact"]
    A --> C["Reliability"]
    A --> D["Cost"]
    A --> E["Availability"]
    A --> F["Scale of output"]

Exam Tip: In a 6-mark question, AQA expects you to discuss both sides — advantages AND disadvantages — and reach a justified conclusion. Do not just list bullet points; write in full sentences and explain your reasoning.

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Worked Example: Evaluating a Proposal

A coastal town is considering building a wind farm or a gas power station. Evaluate which is the better choice.

Arguments for the Wind Farm

• Wind is renewable — it will not run out.
• No CO₂ emissions during operation, helping the UK meet carbon targets.
• The coastal location is likely to have strong, consistent winds.
• Low running costs once built.

Arguments for the Gas Power Station

• Natural gas is reliable — it can generate on demand regardless of weather.
• Gas produces less CO₂ than coal (though still contributes to climate change).
• Can provide a large, steady output to meet the town's energy demand.
• Existing infrastructure (gas pipelines) may already be available.

Conclusion

The wind farm is the better long-term choice because it produces no CO₂, uses a renewable resource, and the coastal location provides reliable wind. However, a backup source may be needed for calm days. A combination of both could provide reliable, lower-carbon electricity.

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Intermittency and Energy Storage

A key challenge for renewable energy is intermittency — wind does not always blow, the sun does not always shine. Solutions include:

Solution	How It Helps
Battery storage	Stores excess electricity for later use
Pumped hydroelectric storage	Pumps water uphill when demand is low; releases it to generate electricity at peak times
Backup gas power stations	Can be switched on quickly when renewables cannot meet demand
Interconnectors	Cables linking countries so electricity can be shared across borders
Demand management	Shifting energy use to times when renewable output is high

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Global Trends in Energy Use

Why Global Energy Demand Is Increasing

• Population growth — more people need more energy.
• Industrialisation — developing countries use more energy as they build infrastructure.
• Higher standards of living — more devices, transport, and heating.

How the Energy Mix Is Changing

• Worldwide, fossil fuels still dominate (about 80% of global energy).
• Renewable energy is the fastest-growing sector.
• Many countries have set targets to reach net zero carbon emissions by 2050.
• The cost of solar and wind has fallen dramatically in the last decade.

graph LR
    A["Global energy demand\nincreasing"] --> B["Fossil fuels still\ndominant (≈80%)"]
    A --> C["Renewables growing\nrapidly"]
    C --> D["Falling costs of\nsolar and wind"]
    B --> E["Pressure to reduce\nCO₂ emissions"]
    E --> C

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Climate Change and Energy Choices

Burning fossil fuels releases carbon dioxide (CO₂), a greenhouse gas. Increased CO₂ in the atmosphere enhances the greenhouse effect, leading to:

• Rising global temperatures
• Melting ice caps and rising sea levels
• More extreme weather events
• Loss of habitats and biodiversity

This is the primary driver behind the shift from fossil fuels to renewable energy.

Exam Tip: AQA may ask you to explain the link between fossil fuel use and climate change. Always include: fossil fuels release CO₂ → CO₂ is a greenhouse gas → enhanced greenhouse effect → global warming.

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Sankey Diagram: Energy Resource Comparison

Imagine comparing a coal power station and a wind farm in terms of energy flow:

Coal Power Station (35% efficient):

graph LR
    A["Chemical energy\nin coal\n(1000 J)"] --> B["Useful electrical\nenergy (350 J)"]
    A --> C["Wasted: internal energy\nof surroundings\n(650 J)"]
    style C fill:#ffcccc,stroke:#cc0000

Wind Turbine (45% efficient):

graph LR
    A["Kinetic energy\nof wind\n(1000 J)"] --> B["Useful electrical\nenergy (450 J)"]
    A --> C["Wasted: kinetic energy\nof air passing turbine\n(550 J)"]
    style C fill:#ffcccc,stroke:#cc0000

The wind turbine is more efficient and produces no CO₂.

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Common Mistakes

Mistake	Correction
Saying renewables have zero environmental impact	All resources have some impact — even solar panels require manufacturing
Confusing reliability with renewability	Tidal is both renewable AND reliable; wind is renewable but NOT always reliable
Saying "nuclear is renewable"	Nuclear fuel is non-renewable (finite uranium supply)
One-sided evaluation	Always discuss advantages AND disadvantages, then reach a balanced conclusion
Forgetting to mention intermittency	This is a key disadvantage of wind, solar, and wave — always mention it

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Summary