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1.2.1Energy

Energy Resources — AQA GCSE Combined Science Trilogy 8464 - Physics Revision Notes & Topical Questions

5 min read 11 parts Lesson 17 of 19

📚 AQA GCSE Combined Science Trilogy 8464 - Physics Hub / Topical Revision
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Part 1 of 9Sources of energy resources

1Renewable resource
Renewable resource a resource replenished at the same rate as it is used.
2Non-renewable resource
Non-renewable resource a finite resource that is used faster than it forms.
3Energy from the Sun
  • Energy from the Sun the Sun transfers energy to Earth by electromagnetic radiation, mainly visible light and infrared.
  • Solar energy heats the atmosphere to give wind and waves.
  • Evaporated water falls as rain and fills reservoirs.
  • Plants use sunlight to form biofuels and, over millions of years, fossil fuels.
4Resources not from the Sun
  • Resources not from the Sun geothermal energy comes from the thermal energy of the Earth's core, nuclear energy from uranium in the crust,
    • and tidal energy mainly from the Moon's gravity.

Part 2 of 9Electricity generation in a power station

1
A fuel is burned, or fission occurs, to release energy.
2
The energy heats water in a boiler to make steam.
3
The steam turns a turbine.
4
The turbine turns a generator that produces electricity.
5
The electricity is sent through the national grid.
6
The steam is condensed and the water is reused.
  • Efficiency
    • no power station is 100% efficient, and a typical thermal station is about 30% efficient because most energy is wasted as thermal energy.

Part 3 of 9Solar cells and solar panels

Solar cell
  • Solar cell a semiconductor device that transfers energy from sunlight to produce an electric current.
  • Cells can power homes, remote signs, communication devices and satellites, and can charge batteries.
Solar panel
  • Solar panel it absorbs infrared radiation to heat water flowing in pipes, which reduces the cost of hot water.
Solar furnace
  • Solar furnace large curved mirrors focus the Sun's rays to boil water and make steam for turbines.
AdvantagesDisadvantages
Renewable, with no fuel costNo output at night and reduced output in cloud
No carbon dioxide during operationLow energy density, so large areas are needed
Useful in remote places without a gridLow power output compared with the mains

Part 4 of 9Wind power

1Process
  • Process the kinetic energy of moving air turns turbine blades, which turn a generator.
2Advantages
  • Advantages wind is renewable, there are no fuel costs and no carbon dioxide or sulfur dioxide is produced during operation.
3Disadvantages
  • Disadvantages the supply is unreliable because the wind is not constant, and the turbines cannot work in very weak or very strong wind.
  • Each turbine produces little electricity, so wind farms are needed.
  • Offshore turbines are hard to maintain and can disrupt shipping routes.

Part 5 of 9Fossil fuels and biofuels

1Fossil fuels
  • Fossil fuels coal, natural gas and oil formed over millions of years from the remains of plants and animals, so they are non-renewable.
  • Their chemical energy originally came from sunlight through photosynthesis.
  • They are used for transport, electricity generation and heating.
2Fossil fuel advantages
  • Fossil fuel advantages they give reliable, on-demand power that does not depend on the weather, and the stations are quick to respond to demand.
3Fossil fuel disadvantages
  • Fossil fuel disadvantages burning them releases carbon dioxide, which adds to global warming, and sulfur dioxide, which causes acid rain.
  • Supplies are finite, so prices rise as demand grows.
  • Extraction damages the environment, and capturing the gases is expensive.
4Biofuels
  • Biofuels fuels such as ethanol and methane made from plant matter.
  • They are renewable, reliable and roughly carbon neutral because the plants absorb carbon dioxide as they grow.
  • They need farmland that could grow food, take time to grow and have about half the energy density of fossil fuels.

Part 6 of 9Nuclear fission power

Nuclear fission
Nuclear fission the splitting of a large nucleus into two smaller nuclei, which releases energy.
Use
  • Use fission heats water to make steam that drives turbines and generators.
Advantages
  • Advantages no carbon dioxide or sulfur dioxide is produced in operation, the fuel has a very high energy density,
    • and the output is reliable and easily controlled.
Disadvantages
  • Disadvantages uranium is finite, so nuclear power is non-renewable.
  • Radioactive waste must be buried and stored for thousands of years.
  • A leak could cause mutations or cancer.
  • The stations are expensive to build and decommission.

Part 7 of 9Water power

Hydroelectric dam
  • Hydroelectric dam water stored high up in a reservoir has gravitational potential energy,
    • which becomes kinetic energy as it flows down and turns the turbine.
  • It is renewable, reliable, quick to start and cheap to run.
  • It floods valleys, needs suitable sites and can be affected by drought.
Tidal barrage
  • Tidal barrage a barrage across an estuary stores water at high tide and releases it through turbines.
  • Tides are regular, so output is predictable.
  • Few estuaries are suitable, and barrages harm habitats and shipping.
Wave power
  • Wave power floating devices use the up-and-down motion of waves to drive generators.
  • Output is not constant because waves vary, and underwater maintenance is difficult.

Part 8 of 9Geothermal energy

1Process
  • Process water is pumped down a shaft to hot rocks and returns as steam or hot water.
  • The steam turns a turbine and generator, and the hot water can heat homes.
2Source
  • Source the heat comes from the decay of radioactive isotopes in the Earth, so it is renewable.
3Advantages
  • Advantages it is reliable and produces no carbon dioxide or sulfur dioxide in operation.
4Disadvantages
  • Disadvantages it needs tectonic activity, so suitable sites are rare and drilling is very expensive.
  • Drilling can release trapped greenhouse gases such as methane.

Part 9 of 9Nuclear fusion and the Sun

Nuclear fusion
Nuclear fusion two light nuclei join to form a heavier nucleus and release energy.
In the Sun
  • In the Sun hydrogen nuclei fuse to form helium nuclei in the core.
Conditions
  • Conditions it needs extremely high temperature and pressure to overcome the repulsion between nuclei.
Fusion reactors
  • Fusion reactors research aims to produce a sustained net energy gain for large-scale, carbon-free electricity.
  • Experiments have released more energy than was delivered to the fuel, but not yet more than the whole facility uses.

Key terms

TermMeaning
Renewable resourceA resource replenished at the same rate as it is used.
Non-renewable resourceA finite resource used faster than it forms.
Nuclear fissionThe splitting of a large nucleus into smaller nuclei, releasing energy.
Nuclear fusionThe joining of light nuclei into a heavier nucleus, releasing energy.
BiofuelA fuel made from plant matter.
Tidal barrageA barrier across an estuary that stores tidal water and releases it through turbines.
Geothermal energyEnergy from the heat stored in rocks inside the Earth.
Photovoltaic cellA solar cell that transfers light energy to electrical energy.

Avoid these mistakes

1
Saying all energy resources come from the Sun — geothermal, nuclear and tidal energy do not.
2
Saying nuclear power is renewable — uranium is finite and the waste stays radioactive.
3
Saying wind and solar are reliable — their supply depends on the weather.
4
Mixing up fission and fusion — fission splits large nuclei and fusion joins small nuclei.
5
Saying biofuels add no carbon dioxide — they release it when burned, but the plants absorbed it when growing.

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