Fuels and energy resources

Electricity has to be generated from something. Each energy resource has advantages and problems.

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Non-renewable resources

Fossil fuels (coal, oil and natural gas) formed over millions of years from the remains of dead plants and animals.
They will run out, and burning them releases carbon dioxide, a greenhouse gas.
Nuclear fuel (uranium) releases no carbon dioxide while the power station runs, but leaves radioactive waste that must be stored safely for a very long time.

Renewable resources

Renewable resources will not run out.
ResourceHow it worksOne drawback
SolarSolar cells turn light into electricityNo electricity at night; less on cloudy days
WindWind turns the blades of a turbineNo electricity when the wind is calm
HydroelectricWater falling from a dam turns turbinesFlooding a valley destroys habitats
TidalTides move water through turbinesFew suitable places
GeothermalHeat from hot rocks undergroundOnly works in certain places
BiofuelBurning plant material or gas from wasteNeeds land to grow crops

How a power station works

In a fossil fuel or nuclear power station:
fuel heats water → steam → steam turns a turbine → the turbine turns a generator → electricity
A wind turbine's blades turn a generator directly.
To compare fuels, find the energy released per gram when they burn.
Worked example

Burning 2 g of fuel A releases 60 kJ. Burning 5 g of fuel B releases 110 kJ. Which fuel releases more energy per gram?

  1. Fuel A: 60 ÷ 2 = 30 kJ per g
  2. Fuel B: 110 ÷ 5 = 22 kJ per g

Answer: Fuel A (30 kJ per g, compared with 22 kJ per g)

Key idea

Fossil fuels and nuclear fuel are non-renewable; solar, wind, hydroelectric, tidal, geothermal and biofuels are renewable. Power stations: heat water, steam turns a turbine, which turns a generator. Compare fuels by energy per gram.

Key words
Power
How quickly energy is transferred, measured in watts (W). 1 kW = 1000 W.
Water
Pure water melts at 0 °C and boils at 100 °C. Its density is 1 g/cm³. Ice is less dense than water, so it floats.

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Quick check

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Extra practice

2 more questions

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  1. Which of these is a non-renewable energy resource?

    1. Solar
    2. Tidal
    3. Wind
    4. Coal
    Show the answer

    Answer: Coal

    Fossil fuels will run out.

  2. Why are fossil fuels non-renewable?

    1. They form in a few days
    2. They take millions of years to form and are used up much faster
    3. They never run out
    4. They are made from wind
    Show the answer

    Answer: They take millions of years to form and are used up much faster

    Fossil fuels formed long ago.

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Sources and references

Checked by the GCSE-ready editorial team, 17 October 2026. Last updated 2 October 2026. Spotted a mistake? Tell us and we will fix it.