P3: National and Global Energy
Energy resources, renewable and non-renewable — comparing different energy sources, the UK energy mix, and why we need to transition to renewables.
📋 Key Definitions
Non-renewable energy resource: A resource that will run out one day because it is being used up faster than it can be replaced. Examples: fossil fuels and nuclear fuel.
Renewable energy resource: A resource that will never run out (or can be replaced within a human lifetime). Examples: solar, wind, hydroelectric, tidal, geothermal, biomass, wave.
Fossil fuels: Coal, oil and natural gas — formed from the remains of ancient organisms over millions of years. They are non-renewable and produce carbon dioxide when burned.
⛏️ Non-Renewable Energy Resources
| Resource | How it works | Advantages | Disadvantages |
|---|---|---|---|
| Coal | Burned to heat water → steam → turbine → generator | Abundant, reliable, relatively cheap | Releases CO₂ and SO₂ (acid rain), will run out, mining damage |
| Oil | Burned in power stations or used as petrol/diesel | High energy density, reliable, transport fuel | Releases CO₂, oil spills, will run out |
| Natural gas | Burned to heat water → steam → turbine → generator | Cleaner than coal, flexible supply, quick to start | Releases CO₂, will run out, imported from other countries |
| Nuclear | Uranium fission releases heat → steam → turbine → generator | Very high energy output, no CO₂, reliable | Radioactive waste, expensive to build and decommission, risk of accidents |
🌿 Renewable Energy Resources
| Resource | How it works | Advantages | Disadvantages |
|---|---|---|---|
| Solar | Solar cells convert light directly to electricity; solar panels heat water | No CO₂, free energy source, can be used in remote areas | Unreliable (needs sunlight), expensive panels, low power for area |
| Wind | Wind turns turbine blades → generator | No CO₂, free energy source, quick to build | Unreliable (needs wind), noisy, visual pollution, low output per turbine |
| Hydroelectric | Water stored behind dam, released to turn turbines | Reliable, can start quickly, high output | Flooding valleys, habitat loss, expensive to build dam |
| Tidal | Rising/falling tides turn turbines in a barrage | Predictable, reliable, no CO₂ | Alters habitats, expensive barrage, few suitable sites |
| Geothermal | Hot rocks underground heat water → steam → turbine | Reliable, no CO₂, free energy source | Few suitable locations, expensive to drill deep |
| Biomass | Organic material (wood, waste) burned to heat water | Carbon neutral (CO₂ released = CO₂ absorbed during growth), reliable | Requires land, slow to grow replacement, still produces CO₂ |
| Wave | Wave motion drives turbines on the coast | No CO₂, free energy source | Unreliable, easily damaged by storms, experimental technology |
📊 Renewable vs Non-Renewable Comparison
| Factor | Non-Renewable | Renewable |
|---|---|---|
| Will they run out? | Yes — finite supply | No — will not run out |
| Reliability | Very reliable — can produce energy on demand | Variable — many depend on weather (except hydro, tidal, geothermal) |
| Environmental impact | Release CO₂ (fossil fuels), radioactive waste (nuclear), pollution | Usually no CO₂, but habitat loss (hydro, tidal), visual/noise pollution (wind) |
| Setup cost | Relatively cheap for fossil fuels; very expensive for nuclear | High initial cost for most; cheap to run after setup |
| Setup time | Quick for gas; years for coal/nuclear | Quick for solar/wind; years for hydro/tidal |
| Running cost | Fuel must be bought continuously | Free energy source (sun, wind, water) — low running costs |
🇬🇧 The UK Energy Mix
Current UK energy mix: The UK generates most of its electricity from natural gas, with a growing proportion from renewables (especially wind and solar). Coal use has dropped significantly. Nuclear provides a steady base load.
- Natural gas — still the largest single source for electricity
- Wind — the largest renewable source in the UK, growing rapidly
- Nuclear — provides steady, reliable base-load power (~15–20%)
- Solar — growing but still a smaller share
- Biomass — used as a replacement for some coal power stations
- Coal — now a very small share and declining
- Hydroelectric — limited by UK geography, small share
🤔 Why Do We Still Use Fossil Fuels?
Fossil fuels remain dominant because: they are reliable (available on demand), the infrastructure already exists (power stations, gas pipelines, petrol stations), and they are relatively cheap to set up compared to some renewable alternatives.
- Fossil fuel power stations can respond quickly to changes in demand
- Existing infrastructure means it costs less to keep using fossil fuels
- Renewables like wind and solar are intermittent — they cannot always provide energy when needed
- Building new renewable infrastructure and energy storage is expensive
🌍 Why We Need to Move to Renewables
We need to transition to renewables because: fossil fuels are finite and will run out, burning fossil fuels releases CO₂ which causes climate change, and pollution from fossil fuels harms health and the environment.
- Finite resources: Coal, oil and gas will eventually run out — we need sustainable alternatives
- Climate change: CO₂ from burning fossil fuels is the main driver of global warming
- Pollution: Fossil fuels produce sulfur dioxide (acid rain), particulates (health problems) and nitrogen oxides
- Energy security: Relying on imported fossil fuels makes countries vulnerable to supply disruptions and price changes
📝 Worked Examples
Worked Example 1 — Evaluating an Energy Source
Question: A country is deciding whether to build a new wind farm or a new gas power station. Give two advantages and two disadvantages of each.
Solution:
Wind farm advantages: No CO₂ emissions, free energy source (wind is free). Disadvantages: Unreliable (needs wind), visual and noise pollution.
Gas power station advantages: Reliable (can produce electricity on demand), can respond quickly to changes in demand. Disadvantages: Releases CO₂ (contributes to climate change), fuel must be purchased (running costs).
Worked Example 2 — Explaining the UK Energy Mix
Question: Explain why the UK still uses natural gas despite wanting to reduce carbon emissions.
Solution: Natural gas is used because: (1) it is reliable and can provide electricity on demand, unlike wind and solar which are intermittent; (2) the UK already has gas infrastructure (pipelines, power stations) so it is cheaper to continue using it; (3) gas power stations can quickly increase or decrease output to match demand; (4) gas produces less CO₂ than coal per unit of energy.
Worked Example 3 — Carbon Neutrality of Biomass
Question: Explain why biomass is described as carbon neutral, even though burning it releases CO₂.
Solution: When biomass is burned, it releases CO₂. However, the plants absorbed CO₂ from the atmosphere through photosynthesis while they were growing. The amount of CO₂ absorbed during growth equals the amount released when burned, so over the full cycle there is no net increase in atmospheric CO₂. This makes biomass carbon neutral. (Note: this only holds if new plants are grown to replace those burned.)
Worked Example 4 — Choosing Energy Sources for Different Needs
Question: A remote island with no connection to the National Grid needs electricity. It has lots of sunshine, steady winds, and a river that could be dammed. Suggest the best energy mix and justify your choices.
Solution: A combination of wind and solar with hydroelectric as backup: (1) Solar panels during the day use the abundant sunshine; (2) Wind turbines provide power when it is windy (including at night); (3) Hydroelectric provides reliable backup when sun and wind are not available; (4) Together these provide a more reliable supply than any single renewable source. This avoids the need for imported fossil fuels.
❓ Practice Questions
Q1: Foundation Define the terms "renewable energy resource" and "non-renewable energy resource". Give two examples of each.
Q2: Foundation Give two reasons why the UK still uses fossil fuels for electricity generation.
Q3: Foundation Explain why tidal energy is more reliable than wind energy.
Q4: Higher A country currently generates 60% of its electricity from coal. It aims to reduce this to 10% in 20 years. Suggest which renewable sources it could use instead and discuss the challenges it would face.
Q5: Higher Explain why nuclear power is classified as non-renewable even though it does not produce CO₂ during operation.
Q6: Higher Compare the environmental impact of hydroelectric power and wind power. Include both positive and negative effects.
✅ Answers
- A renewable energy resource is one that will never run out (or can be replaced within a human lifetime). Examples: solar, wind. A non-renewable resource is one that will run out because it is being used faster than it can be replaced. Examples: coal, natural gas.
- 1) Fossil fuels are reliable — they can produce electricity on demand, unlike some renewables. 2) The infrastructure already exists (power stations, gas pipelines) so it is cheaper to continue using them than to build new renewable infrastructure.
- Tidal energy is more reliable because tides are predictable and happen twice daily regardless of weather. Wind energy depends on weather conditions — if there is no wind, no electricity is generated.
- The country could use wind and solar (both quick to build, no CO₂), hydroelectric (reliable backup), and possibly nuclear (reliable, no CO₂, but expensive and slow to build). Challenges: (1) renewables are intermittent, so need energy storage or backup; (2) building new infrastructure is expensive; (3) some renewables need specific geography (hydro needs rivers/hills); (4) nuclear takes many years to build and produces radioactive waste.
- Nuclear power is non-renewable because it uses uranium fuel, which is a finite resource that will eventually run out. It cannot be replaced within a human lifetime. Even though it does not produce CO₂, the fuel supply is limited, which is the definition of non-renewable.
- Hydroelectric positive: no CO₂ emissions, reliable. Negative: building dams floods valleys, destroys habitats, displaces communities. Wind power positive: no CO₂, minimal land impact (land can still be farmed). Negative: visual pollution, noise, can kill birds and bats, unreliable without wind. Both are renewable and do not produce CO₂ during operation.
🎯 Exam Tips
- When comparing energy sources, always give both advantages AND disadvantages — exam questions often ask you to evaluate or discuss.
- Use the correct terms: reliable means it can provide energy on demand; renewable means it will not run out.
- If asked "why do we still use fossil fuels?", the key points are: reliability, existing infrastructure, cost.
- If asked "why switch to renewables?", the key points are: finite resources, climate change, pollution.
- Biomass is carbon neutral — be prepared to explain this using photosynthesis and the carbon cycle.
- Always consider the full picture — not just whether a source is renewable, but also reliability, cost, and environmental impact.
🔢 Maths Skills
Mathematical Skills
You need to interpret energy mix data from charts and tables, calculate percentages from given data, and compare costs of different energy sources. Working with percentage change is also important when analysing trends in energy use over time.
Maths Example
In 2010, a country generated 40% of its electricity from coal. In 2024, this fell to 5%. Calculate the percentage decrease in coal's share of electricity generation.
Percentage decrease = ((40 − 5) ÷ 40) × 100 = (35 ÷ 40) × 100 = 87.5% decrease in coal's share.
⚠️ Common Misconceptions
Watch Out!
1. Wrong: Nuclear power is a renewable energy source Correct: Nuclear power is non-renewable — it uses uranium fuel which is finite and will run out, even though it does not produce CO₂ during operation
2. Wrong: Biomass has zero environmental impact because it is carbon neutral Correct: Biomass still produces CO₂ when burned and requires land to grow, which can lead to deforestation and habitat loss — carbon neutral only applies if replacement plants are grown
3. Wrong: Renewable energy sources are always the best choice Correct: Renewables can be unreliable (wind and solar depend on weather), may have high setup costs, and can cause environmental damage (e.g. flooding valleys for hydroelectric) — the best choice depends on the specific situation
✍️ 6-Mark Question
Extended Answer
6 marks: Evaluate whether the UK should switch entirely to renewable energy sources for electricity generation. Include arguments for and against, and give a justified conclusion.
Arguments for switching entirely to renewables: (1) Fossil fuels are finite and will eventually run out, so we must transition to sustainable sources. (2) Burning fossil fuels releases CO₂, which is the main cause of climate change — renewables produce no CO₂ during operation. (3) Using renewables improves energy security by reducing dependence on imported fossil fuels, making the UK less vulnerable to supply disruptions and price changes. (4) Renewable technology is improving and costs are falling. Arguments against switching entirely: (1) Wind and solar are intermittent — they cannot generate electricity when there is no wind or sunlight, so backup power or large-scale energy storage is needed. (2) Building new renewable infrastructure is very expensive and takes time. (3) Some renewables cause environmental damage — hydroelectric dams flood valleys and destroy habitats. (4) Nuclear power provides reliable, low-carbon base-load electricity and may still be needed. Conclusion: The UK should aim to generate most electricity from renewables but a complete switch is currently impractical due to reliability concerns. A mix of renewables with some nuclear or gas backup, plus improved energy storage technology, would be a more realistic and balanced approach.
Mark scheme: 1 mark — at least one argument for renewables (finite resources); 1 mark — at least one argument for renewables (climate change); 1 mark — at least one argument against (intermittency); 1 mark — at least one argument against (cost or environmental damage); 1 mark — both sides considered; 1 mark — justified conclusion with reasoning
📊 AO3: Analyse & Evaluate
Analysis and Evaluation
The table below shows the electricity generation mix for two countries in 2024:
Country A: Coal 5%, Natural gas 35%, Nuclear 20%, Wind 25%, Solar 10%, Hydro 5%
Country B: Coal 45%, Natural gas 15%, Nuclear 0%, Wind 10%, Solar 20%, Hydro 10%
(a) Calculate the percentage of electricity generated from renewable sources for each country.
(b) Country B plans to close all coal power stations by 2035 and replace them with wind and nuclear. Explain one advantage and one disadvantage of this plan.
(c) A politician from Country B claims "We should replace all coal with solar because solar is the cheapest renewable." Evaluate this claim using the data.
Answers: (a) Country A renewables = wind 25% + solar 10% + hydro 5% = 40%. Country B renewables = wind 10% + solar 20% + hydro 10% = 40%. (b) Advantage: replacing coal with wind and nuclear would eliminate CO₂ emissions from coal, reducing the country's contribution to climate change. Disadvantage: nuclear power stations are very expensive and take many years to build, and wind is intermittent so cannot fully replace the reliable base-load that coal provides. (c) The claim is too simplistic. While solar may be cheap to run, Country B already generates 20% from solar — expanding further has limitations because solar only works during daylight hours. Wind already provides 10% and could be expanded more easily in a country with suitable weather. A mix of wind and nuclear (as originally planned) would provide more reliable electricity than solar alone, since nuclear is not weather-dependent. The politician's claim ignores the reliability issue and the need for a balanced energy mix.
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