3.4 Energy and the Environment

A free GCSE Physics lesson for AQA (8463) from OBA School: the environmental effects of fossil fuels, nuclear power and renewable resources, and how to evaluate them. Watch the video, read the explanation and worked examples, then try the revision questions. You can work through the full lesson, with every video, practice quizzes and printable worksheets with mark schemes, in our free online course.

What you will learn

• Describe how burning fossil fuels causes global warming and acid rain, and how the effects can be reduced
• Explain the advantages and disadvantages of nuclear power for the environment
• Describe the environmental advantages and disadvantages of renewable energy resources
• Use data to compare and evaluate the environmental impact of different energy resources

Key words

• Greenhouse gas: A gas such as carbon dioxide that absorbs infrared radiation in the atmosphere, keeping the Earth warmer.
• Global warming: The rise in the Earth’s average temperature, linked to increasing levels of greenhouse gases.
• Acid rain: Rain made acidic by gases such as sulfur dioxide dissolving in water in clouds.
• Carbon capture and storage: (CCS) Collecting CO₂ from power stations and storing it deep underground instead of releasing it.
• Radioactive waste: Used nuclear fuel and other materials that give out harmful radiation and must be stored safely for a very long time.
• Decommis- sioning: Safely shutting down and taking apart a power station at the end of its working life.

Problems with fossil fuels

Burning coal, oil and gas releases carbon dioxide, a greenhouse gas. The amount of CO₂ in the atmosphere is increasing, and most scientists agree this increases the greenhouse effect, causing global warming and climate change (rising sea levels, more extreme weather).

Many fossil fuels contain sulfur impurities. When they burn they produce sulfur dioxide, which dissolves in water in clouds to cause acid rain. Burning also releases smoke particles (soot) that harm health.

• Reducing acid rain: remove the sulfur from the fuel before burning it (this is done for natural gas), or remove SO₂ from the waste gases before they leave the chimney.
• Running out: fossil fuels are non-renewable. Oil and gas reserves may run low within decades; coal will last longer.

Carbon capture and storage

Carbon capture and storage (CCS) could let fossil-fuel power stations release much less CO₂. The CO₂ is separated from the waste gases, piped away and pumped deep underground, for example into old oil and gas fields under the sea bed, where a layer of rock above it stops it escaping.

Worked example: how much CO₂ does CCS save?

A gas-fired power station generates 2.0 × 10⁹ kWh of electricity a year, releasing 0.49 kg of CO₂ per kWh.
CO₂ without CCS = 2.0 × 10⁹ × 0.49 = 9.8 × 10⁸ kg
CCS captures 90%, so 10% is still released: 0.10 × 9.8 × 10⁸ = 9.8 × 10⁷ kg

Answer: 9.8 × 10⁷ kg released instead of 9.8 × 10⁸ kg

Key fact: CCS is expensive, it uses some of the power station’s own output to run, and it does nothing about fossil fuels running out.

Nuclear power and the environment

• no greenhouse gases or acid rain while generating – nothing is burnt; Disadvantages used fuel is radioactive waste that must be stored safely for thousands of years
• huge energy from a small mass of fuel, so little fuel to mine and transport; Disadvantages an accident could spread radioactive material over a wide area, affecting people for many years
• reliable: runs day and night; Disadvantages very expensive to build and to decommission

Renewable resources and the environment

Advantages: they never run out; they release no greenhouse gases, sulfur dioxide or radioactive waste while generating; small systems (such as solar cells) can supply places that the grid does not reach.

Disadvantages – every resource affects the environment in some way:

• Wind farms; Environmental effect noise and visual impact; risk to birds; many turbines cover a large area
• Hydroelectric dams; Environmental effect valleys flooded, destroying habitats and sometimes homes
• Tidal barrages; Environmental effect change estuary habitats for birds and fish
• Solar farms; Environmental effect cover large areas of land
• Biofuels; Environmental effect land used for fuel crops instead of food; forests may be cleared

Renewables cannot yet meet all of the world’s demand, and some are unreliable, so fossil fuels are still used. Building turbines and panels also releases some CO₂, so over their whole lifetime no resource is completely carbon-free.

Exam tip: When asked to evaluate energy resources, compare them under clear headings – greenhouse gases, other pollution, waste, effect on land and habitats, reliability, cost – and finish with a judgement.

Common mistakes

• Mixing up the gases: CO₂ causes global warming; SO₂ causes acid rain.
• Saying nuclear power stations release greenhouse gases or cause acid rain. Their big problem is radioactive waste.
• Writing “renewables are better for the environment” with no detail. Name the specific effect (e.g. flooding valleys).
• Saying CCS “destroys” carbon dioxide. It only stores it underground.

Revision questions

Try these, then check your answers below each one.

Question 1. Which gas from burning fossil fuels causes acid rain? (Choose from: sulfur dioxide, carbon dioxide, oxygen, water vapour.)

Answer: sulfur dioxide

Working: Sulfur impurities burn to form sulfur dioxide, which dissolves in water in clouds to make acid rain. Carbon dioxide causes global warming.

Question 2. True or false? Renewable energy resources have no effect on the environment.

Answer: False

Working: False. They release no CO₂ while generating, but dams flood valleys, barrages change estuaries, wind farms are noisy, and building them releases some CO₂.

Question 3. What is the name of the technology that collects carbon dioxide from power stations and stores it deep underground?

Answer: carbon capture and storage

Working: Carbon capture and storage (CCS) separates CO₂ from waste gases and pumps it into places such as old oil and gas fields.

Related lessons

• Previous lesson: 3.3 Power from the Sun and the Earth
• Next lesson: 3.5 Big Energy Issues
• In this chapter: 3.1 Energy Demands
• In this chapter: 3.2 Energy from Wind and Water

Continue in the full course

This lesson is section 3.4 (AGCPH0304) of our free GCSE Physics course for AQA. In the full course you get every video for this section, a self-marking practice quiz, a printable worksheet with a mark scheme, chapter tests, and your progress saved. Go to the full GCSE Physics course.