Energy Resources: Renewable and Non-Renewable KS3 Physics

Energy resources are the sources from which we obtain the energy needed to heat homes, power transport, and generate electricity. The key distinction at KS3 is between non-renewable resources — which will eventually run out — and renewable resources, which are continually replenished by natural processes. This topic is a core part of KS3 physics, typically taught in Year 9.

What is the difference between renewable and non-renewable energy resources?

Feature | Non-renewable | Renewable
Supply | Finite — will run out | Continually replenished
Examples | Coal, oil, natural gas, nuclear fuel | Solar, wind, hydroelectric, tidal, biomass, geothermal
Carbon emissions | High (fossil fuels) or low (nuclear) | Very low or zero during operation
Reliability | Reliable on demand (can be stored) | Often intermittent (depends on weather or season)
Environmental impact | Significant (pollution, CO₂, mining) | Lower, but not zero (land use, manufacturing)

Non-renewable energy resources

Fossil fuels

Coal, crude oil (and its refined products — petrol, diesel, jet fuel), and natural gas are fossil fuels. They formed over millions of years from the compressed remains of ancient organisms. When burned, they release energy as heat; this heat is used to raise steam, which drives turbines to generate electricity.

Advantages: energy-dense; reliable and controllable; existing infrastructure is mature. Disadvantages: burning releases CO₂ (greenhouse gas driving climate change), SO₂ and NOₓ (acid rain), and soot. Supply is finite and unevenly distributed geographically.

Nuclear fuel (uranium)

Nuclear power stations use uranium (and sometimes plutonium) as fuel. In a process called nuclear fission, the nucleus of a uranium atom is split by a neutron, releasing a large amount of energy as heat. This heat raises steam to drive turbines. No CO₂ is produced during operation.

Advantages: very energy-dense (a small amount of fuel yields enormous energy); no greenhouse gas emissions during generation; reliable baseload power. Disadvantages: radioactive waste remains hazardous for thousands of years and requires careful long-term storage; high construction costs; risk of accidents (e.g. Chernobyl 1986, Fukushima 2011).

Renewable energy resources

Solar energy

Solar panels (photovoltaic cells) convert sunlight directly into electricity. Solar thermal panels heat water using sunlight. In 2023, solar generated approximately 14 TWh of electricity in the UK — about 4.2% of total generation (Digest of UK Energy Statistics, DESNZ 2024).

Advantages: no fuel cost; no emissions during operation; scalable from individual panels to utility farms. Disadvantages: intermittent — only works in daylight and is reduced on cloudy days; manufacturing panels has an environmental cost; requires storage (batteries) or backup for nights and overcast periods.

Wind energy

Wind turbines convert the kinetic energy of moving air into electricity via a generator. The UK has the largest installed offshore wind capacity in the world: in 2023, wind provided around 29% of UK electricity generation (DESNZ 2024).

Advantages: no fuel cost; no emissions during operation; offshore wind has high capacity factors. Disadvantages: intermittent — output depends on wind speed; visual impact; noise; some concerns about effects on birds and marine life; energy must be stored or balanced by other sources when wind is low.

Hydroelectric power (HEP)

Water stored in an upland reservoir is released through turbines. Gravitational potential energy of the water is converted to kinetic energy, then to electrical energy.

Advantages: reliable and controllable; pumped storage systems (e.g. Dinorwig in North Wales) can respond within seconds to changes in demand; no emissions during generation. Disadvantages: large dams flood valleys, displacing communities and destroying habitats; UK geography limits large-scale expansion.

Tidal energy

Tidal barrages or tidal stream turbines harness the movement of tides. Tides are predictable (unlike wind or solar), making tidal energy highly reliable.

Advantages: fully predictable; no emissions. Disadvantages: high construction costs; limited suitable locations; can affect tidal ecosystems.

Biomass

Biomass includes wood, agricultural waste, and purpose-grown energy crops. When burned, the carbon released was recently absorbed from the atmosphere by the growing plant — making it roughly carbon-neutral in theory (though transport and processing add emissions in practice).

Advantages: can use waste material; controllable (unlike wind or solar). Disadvantages: burning still produces particulates and local air pollution; land use competes with food production; true carbon neutrality depends on replanting rates.

Geothermal energy

Hot rocks underground heat water (or steam) that is piped to the surface and used directly for heating or to drive turbines. Particularly viable in volcanically active areas (Iceland, New Zealand) or in deep geothermal projects such as those being developed in the UK's geologically older areas (e.g. Cornwall).

Advantages: highly reliable (not weather-dependent); low emissions. Disadvantages: limited to geologically suitable areas; drilling is expensive.

Comparing energy resources: a summary table

Resource | Renewable? | Reliable? | CO₂ during operation? | Key drawback
Coal | No | Yes | High | Pollution, CO₂
Natural gas | No | Yes | Medium | CO₂, finite supply
Nuclear | No (uranium) | Yes | None | Radioactive waste
Solar | Yes | Intermittent | None | Needs storage
Wind | Yes | Intermittent | None | Needs storage / backup
Hydroelectric | Yes | Reliable | None | Habitat disruption
Tidal | Yes | Predictable | None | High cost, limited sites
Biomass | Yes | Reliable | Low (net) | Land use, pollution
Geothermal | Yes | Reliable | None | Limited locations

The Department for Education's Science Programmes of Study for Key Stage 3 requires pupils to compare the ways in which energy is stored, transferred, and dissipated, and to evaluate the use of different energy resources. BBC Bitesize KS3 Physics covers all major renewable and non-renewable energy resources, how they work, and their advantages and disadvantages.

Frequently asked questions

Why are fossil fuels described as non-renewable?

Fossil fuels — coal, oil, and natural gas — took hundreds of millions of years to form from the compressed remains of ancient organisms. We are burning them at a rate many millions of times faster than they could ever be replaced. Once the reserves we can economically access are exhausted, there is no practical way to replenish them on a human timescale. This is what makes them non-renewable. Current estimates suggest that at present consumption rates, known reserves of oil could last around 50 years, natural gas around 50–60 years, and coal around 130 years, although new discoveries and changes in demand affect these figures.

What is the difference between energy stored in a resource and the electricity it generates?

Not all the energy in a fuel becomes useful electricity. In a typical fossil fuel power station, only about 35–40% of the energy in the fuel is converted to electrical energy — the rest is wasted as heat lost to the cooling water and exhaust gases. This ratio is the power station's efficiency. Renewable sources like wind and solar also have efficiencies: a modern wind turbine converts around 35–45% of the kinetic energy in wind into electricity; solar panels typically convert 15–22% of incident solar energy into electricity. Efficiency improvements reduce how much fuel (or how many panels or turbines) are needed to generate a given amount of electricity.

What does intermittent mean in the context of energy resources?

An intermittent energy resource is one that does not generate electricity continuously but only when natural conditions are right. Solar panels only generate electricity when the sun is shining; wind turbines only generate when the wind blows within a useful speed range (typically 3–25 m/s). Intermittency is a major challenge for grid operators because electricity demand does not stop when the sun sets or the wind drops. Solutions include large-scale battery storage, pumped hydroelectric storage (storing surplus energy by pumping water uphill and releasing it when needed), interconnectors to neighbouring countries, and keeping backup gas or nuclear capacity available.

How does nuclear energy work if it does not involve burning fuel?

In a nuclear power station, energy is released not by burning but by nuclear fission — splitting the nucleus of a heavy atom. When a neutron strikes a uranium-235 nucleus, the nucleus splits into two smaller nuclei and releases two or three more neutrons plus a large amount of energy as heat. Those neutrons go on to split more nuclei — a chain reaction. The heat is used to boil water, producing steam that drives turbines connected to generators, exactly as in a fossil fuel station. The key difference is that no carbon is burned, so no CO₂ is produced during operation. The challenge is that the split products (fission products) are highly radioactive and must be safely contained and stored for very long periods.

Explore energy resources with a Socratic physics tutor who guides you to compare and evaluate sources — visit aitutors.me.