Ch 14 · 1.7.3 Energy Resources · O Level Physics 5054

Topic 14 of 17 in Motion, Forces and Energy — O Level Physics 5054 — 48 lessons.

Introduction

Every time you switch on a light, energy has been transferred from a resource somewhere: coal, gas, sunlight, wind or falling water. This lesson compares the main energy resources: how each one gives us electricity, and the pros and cons the syllabus asks about. (Syllabus section 1.7.3.)

Key ideas — Renewable and non-renewable

🧑‍🏫 Teacher's explanation

Think of energy resources like a bank account. Non-renewable resources are like a fixed inheritance; once you spend the money, it is gone forever because you cannot earn it back. Renewable resources are like a weekly salary; as long as you keep working, the money keeps coming in, allowing you to use it continuously without ever hitting a zero balance.

📖 Definitions

🔍 Worked example — Easy

Classify the following sources as renewable or non-renewable: Coal, Wind, Uranium, and Tidal energy.

🔍 Worked example — Standard

A power station uses natural gas to generate electricity. State whether this is a renewable or non-renewable resource and give one reason why.

🔍 Worked example — Exam-style

A student claims that solar energy is non-renewable because the sun will eventually die. Evaluate this claim based on the Cambridge definition of renewable resources.

⚠️ Common errors

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🎯 Exam question

(a) State whether coal is a renewable or non-renewable resource. [1] (b) Explain why coal is classified this way. [1] (c) Suggest one environmental disadvantage of using coal. [1] [3 marks]

Key ideas — The power-station chain

Many power stations work the same way:

🧑‍🏫 Teacher's explanation

Think of a power station as a giant energy conversion factory. Most power stations don't actually 'create' electricity; they just transform energy from one form to another. Imagine a tea kettle on a stove: the heat from the flame turns water into steam, and if you put a little windmill on top of the kettle, the steam would spin it. That's the core concept.

📖 Definitions

🔍 Worked example — Standard

A wind turbine rotates at a constant speed. It provides 2.5 kW of electrical power. How much energy does it generate in 2 minutes?

🔍 Worked example — Exam-style

A hydroelectric dam stores potential energy in water held at a height. If the water falls from a height of 50 m and the turbine/generator system is 80\% efficient, calculate the electrical energy produced from 100 kg of water. (Use g = 10 m/s^2)

⚠️ Common errors

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🎯 Exam question

Key ideas — How each resource is used

🧑‍🏫 Teacher's explanation

Think of energy resources as different ways to 'kickstart' a machine. Most of our power comes from a very specific sequence: something (heat, wind, or water) pushes a turbine, which is like a giant spinning fan. This fan is connected to a generator, which uses magnets and coils to turn that motion into electricity. It is like a relay race where the energy is passed from one form to another until it reaches your plug.\n\nWe categorize these resources into two groups: renewable (they won't run out because they are replenished naturally, like wind or sun) and non-renewable (they take millions of years to form and will eventually disappear, like coal or oil). When evaluating them, we don't just ask 'is it green?'; we ask: 'Is it reliable? (Does it work when the wind stops?)', 'Is it available? (Can we use it anywhere?)', and 'What is the environmental cost? (Does it cause pollution?)'.

📖 Definitions

🔍 Worked example — Easy

A hydroelectric power station uses the gravitational potential energy of water stored in a reservoir. If the water falls through a height of h = 50 m and the mass of water is m = 1000 kg, calculate the theoretical potential energy available. (Use g = 10 m/s^2 for O Level).

🔍 Worked example — Standard

A wind turbine converts kinetic energy to electrical energy. If the turbine produces 2.5 kW of power and operates for 2 hours, calculate the total energy produced in Joules.

🔍 Worked example — Exam-style

A thermal power station uses a boiler to heat water. The steam produced has a mass flow rate of 5.0 kg/s. If the specific heat capacity of water is c = 4200 J/(kg·circC) and the temperature increase is Δ T = 100circC, calculate the power transferred to the steam per second.

⚠️ Common errors

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🎯 Exam question

Key ideas — Comparing resources

The syllabus limits the comparison to three things: renewable or not, when and whether it is available, and impact on the environment.

🧑‍🏫 Teacher's explanation

Think of energy resources like a bank account. Non-renewable resources are like a fixed inheritance; once you spend it, it is gone forever. Renewable resources are like a salary; as long as the job (the sun, the wind, the tides) continues, you can keep receiving it, but you can't always predict exactly when the paycheck arrives.\n\nWhen we compare these resources, we aren't looking at how much energy they produce in a single moment, but rather how reliable they are and what they do to the world around us. We categorize them by whether they can be replenished (renewable) or if they will eventually run out (non-renewable), how much we can rely on them being 'on' when we need them, and whether they pollute the air or change the landscape.

📖 Definitions

🔍 Worked example — Easy

A student is asked to classify 'Solar Power' and 'Coal'. State whether each is renewable or non-renewable.

🔍 Worked example — Standard

Compare Wind power and Hydroelectric power in terms of 'availability' and 'environmental impact'.

🔍 Worked example — Exam-style

A power station uses nuclear fuel. State one advantage and one disadvantage regarding its environmental impact and availability.

⚠️ Common errors

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🎯 Exam question

Worked example

Example: choosing resources. A small island has strong winds, steep valleys with heavy rainfall and no fossil fuels. Suggest two resources and discuss them.

🔍 Worked example — Easy

A village uses a wind turbine to generate electricity. State whether wind is a renewable or non-renewable resource and identify one disadvantage related to its availability.

🔍 Worked example — Standard

A power station uses fossil fuels to generate electricity. Describe the sequence of energy conversion involving a boiler, turbine, and generator.

🔍 Worked example — Exam-style

An island relies on hydroelectric power. The island has steep valleys and high rainfall. Discuss one advantage and one environmental disadvantage of this resource.

⚠️ Common errors

Common mistakes

Practice

Answers: (1) Renewable: any three of solar, wind, hydroelectric, tides, waves, geothermal, biofuels. Non-renewable: fossil fuels (coal, oil, gas) and nuclear fuel. (2) Coal is burned, releasing chemical energy that heats water in a boiler into high-pressure steam; the steam turns a turbine, which drives a generator. (3) Advantage: renewable / no polluting gases. Disadvantage: only works when windy / noisy / visual impact. (4) Water stored behind a dam can be released whenever it is needed; solar cells need light, so they generate nothing at night. (5) Nuclear: long-lasting radioactive waste (or accident risk). Fossil fuels: CO₂ emissions causing global warming (or polluting gases).

Ch 14 · 1.7.3 Energy Resources · O Level Physics 5054

All chapters in Motion, Forces and Energy