National and Global Energy Resources (P1.3)
Non-renewable energy sources
Finite resources that will eventually run out; cannot be replaced on a human timescale.
| Source | How electricity is generated | Advantages | Disadvantages |
|---|---|---|---|
| Coal | Steam turbine | Reliable, large-scale | CO₂, SO₂, NOₓ; ash waste |
| Oil | Steam turbine | Reliable | CO₂; limited reserves |
| Natural gas | Steam turbine / gas turbine | Flexible; lower CO₂ than coal | Still emits CO₂ |
| Nuclear | Steam turbine (fission heat) | Very low CO₂; huge energy density | Radioactive waste; high capital cost |
Nuclear: uranium/plutonium fission releases enormous heat → steam → turbine → generator. No direct CO₂ during operation but waste is highly radioactive for thousands of years.
Renewable energy sources
Infinite resources — replenished naturally; do not run out.
| Source | How energy is generated | Advantages | Disadvantages |
|---|---|---|---|
| Solar (photovoltaic) | Sunlight → electricity directly | No fuel cost; no pollution during use | Dependent on sunlight; land use |
| Wind turbines | Wind rotates blades → generator | No emissions during use | Intermittent; visual/noise impact |
| Hydroelectric | Gravity of water → turbine → generator | Reliable, controllable output | Flooding habitat; expensive dam |
| Tidal | Tidal flow → turbine | Predictable; no emissions | Limited sites; habitat disruption |
| Geothermal | Heat from Earth's interior → steam | Reliable | Limited to volcanic regions |
| Biomass | Burn organic material → steam turbine | Carbon-neutral if managed sustainably | Land use; can emit CO₂ and particulates |
| Wave | Wave oscillation → generator | No emissions | Expensive; unreliable |
Environmental considerations
- CO₂: fossil fuels → enhanced greenhouse effect → global warming.
- SO₂ and NOₓ: acid rain from coal and oil.
- Land use: wind/solar farms require large areas.
- Habitat disruption: hydroelectric dams flood valleys.
- Nuclear waste: long-term storage problem.
- Visual and noise pollution: wind turbines.
Reliability and intermittency
Fossil fuels and nuclear: dispatchable — can generate on demand.
Wind/solar: intermittent — depends on weather → need backup or storage.
Hydroelectric/tidal: more predictable.
Energy storage: batteries, pumped hydro, compressed air — needed to balance intermittent supply.
Common exam errors
- Saying nuclear energy is renewable — it uses uranium, which is finite.
- Saying solar and wind produce no pollution at all — manufacturing solar panels and turbines has an environmental cost; only during operation are they emission-free.
- Saying biomass is always carbon-neutral — it is only carbon-neutral if sustainable management balances the CO₂ released.
AI-generated · claude-opus-4-7 · v3-deep-combined-science