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Learn0625Papers 2, 4 · ExtendedMotion, forces and energyEnergy resources
Motion, forces and energy · Subtopic 9 of 10

Energy Resources

Most of our energy comes, directly or indirectly, from the Sun: fossil fuels, biofuels, wind, waves, hydroelectric and solar. Tides, geothermal and nuclear fuel are the exceptions. Renewable resources won't run out; non-renewable ones will. Every resource is a trade-off between cost, reliability, scale and pollution.

Cambridge 5054 Paper 1Cambridge 5054 Paper 2Cambridge 0625 Papers 2, 4Cambridge 0625 Papers 1, 3Edexcel 4PH1 Paper 1PEdexcel 4PH1 Paper 2P≈ 25 minRevision 5 · updated 2026-10-27
Section 1 of 14

Learning objectives

  • Describe how electricity is generated from each major resource.
  • Classify resources as renewable or non-renewable, and trace them back to the Sun.
  • Compare resources on reliability, scale, cost and environmental impact.
  • Do efficiency and power calculations for power stations and solar panels.
Pause and think

Coal is the remains of ancient plants. Where did the energy stored in coal originally come from?

Section 2 of 14

Core idea

Start hereSpinning magnets

Coal, nuclear, wind and hydro power stations look nothing alike, yet almost all do the same final job: spin a turbine connected to a generator. The differences lie in what spins the turbine, and what that costs.

The big idea

Most electricity: turbine + generator. Compare sources on renewability, reliability, pollution and cost.

1. Power stations

How a power station works
burn fuelboil watersteam turns turbinegenerator → gridchemical → thermal → kinetic → electrical
Wind and hydroelectric skip the boiling: moving air or water turns the turbine directly. Solar cells make electricity with no moving parts.
Energy flow in a fossil-fuel station

Typical efficiency 35–40%; most waste is heat at the cooling towers.

Worked exampleEfficiency of a station

40% efficient, output 400 MW.

Goal
Input and waste.
Strategy
Input = output ÷ efficiency.
  1. 400÷0.40=1000 MW400\div0.40=1000\text{ MW}
    Input from fuel.
  2. 1000−400=600 MW1000-400=600\text{ MW}
    Waste heat.
Answer10001000 MW in; 600600 MW wasted.
✓ Check400/1000=40%400/1000=40\% ✓.

2. Comparing sources

  • Fossil fuels: reliable; CO₂, finite.
  • Nuclear: no CO₂, reliable; radioactive waste.
  • Wind, solar: renewable, clean; weather-dependent.
  • Hydroelectric: reliable; floods land.
  • Geothermal, tidal: location-dependent.
Common misconceptionRenewable means clean? Usually, but building dams or panels still has environmental costs.
Pause and think

Why is solar power unreliable for night-time demand?

Summary

  • Turbine + generator.
  • Weigh renewability, reliability, pollution.
Key words
Renewable
Will not run out.
HistoryThe first power station. In 18821882 Thomas Edison's Pearl Street Station in New York began supplying electricity to 5959 customers, using coal-fired steam engines. Within a few decades, cities across the world were electrified.
Fun factOne hour of sunlight. The sunlight reaching the Earth in about one and a half hours carries roughly as much energy as the whole world uses in a year. The challenge isn't the amount; it's collecting and storing it.
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