Energy Resources

This lesson explains Energy Resources for Cambridge IGCSE Physics 0625. It separates the Core requirements from the additional Supplement work for Extended candidates. Focus on the cause-and-effect explanation and the exact quantities being compared. Work through the example before testing the same skill without notes.

Which energy resources must you know?

The syllabus includes energy obtained or electrical power generated from:

• fossil fuels
• biofuels
• water, including waves, tides and hydroelectric dams
• geothermal resources
• nuclear fuel
• sunlight using solar cells
• infrared and other electromagnetic radiation from the Sun using solar panels
• wind

Where relevant, understand the chain involving a boiler, turbine and generator.

How should Core candidates compare energy resources?

Use the factors named in the syllabus:

• renewability
• availability
• reliability
• scale
• environmental impact

A strong comparison links each point to the resource and the situation.

Resource	Useful advantages	Important limitations
Fossil fuels	reliable, controllable, large-scale generation	finite; carbon dioxide and other pollutants may be released
Biofuels	renewable when crops are replaced; fuel can be stored	land use, transport and combustion impacts
Hydroelectric	renewable; output can be controlled; no fuel is burned during operation	high construction impact; land and habitats may be flooded; rainfall dependent
Wind	renewable; no fuel is burned during operation	variable output; suitable sites are needed
Solar cells	renewable; useful for small or remote systems	output varies with light level; storage or backup may be needed
Tidal	renewable and predictable	limited suitable locations; environmental and construction impacts
Wave	renewable	variable conditions; difficult marine engineering and maintenance
Geothermal	reliable in suitable regions	limited suitable locations; drilling and construction costs
Nuclear fuel	large continuous output; no carbon dioxide from fuel combustion during operation	finite fuel; radioactive waste and decommissioning require management

Do not write only “good for the environment” or “expensive”. Name the actual advantage, limitation or consequence.

Which ideas are Supplement content?

Supplement candidates also need to know that radiation from the Sun is the main source of energy for most energy resources. The exceptions identified by the syllabus are:

• geothermal
• nuclear
• tidal

The Sun releases energy through nuclear fusion. The syllabus also requires awareness that research is investigating how fusion energy might be used to generate electricity on a large scale.

Quantitative efficiency equations are also Supplement. Revise them on the linked efficiency lesson rather than treating all energy-resource content as identical across both tiers.

Original exam-style question

A community is comparing a small hydroelectric scheme with a diesel generator.

(a) State one advantage of the hydroelectric scheme. [1]

A valid answer is that no fuel has to be purchased or burned during operation.

(b) State one disadvantage of the hydroelectric scheme. [1]

A valid answer is that building the dam may flood land and damage habitats.

(c) Explain why hydroelectric energy is renewable. [2]

Water is returned through the water cycle, so the resource is replenished naturally rather than permanently depleted by use.

(d) State the original source of the energy transferred in the water cycle. [1]

The Sun.

Original marking guidance

• one mark for a specific valid advantage
• one mark for a specific valid disadvantage
• one mark for natural replenishment
• one mark for linking this to continued replacement of the water resource
• one mark for the Sun

Common mistakes

• Calling nuclear fuel renewable. Nuclear fuel is finite.
• Confusing solar cells and solar panels. Solar cells generate electricity from light; solar panels can use solar radiation to heat water.
• Saying the Sun is the source of every resource. Remember the geothermal, nuclear and tidal exceptions.
• Confusing reliable with renewable. A resource can be renewable but variable.
• Giving an unqualified environmental claim. Name the pollutant, habitat effect, waste issue or land-use consequence.
• Treating all content as Core. Fusion, the Sun-source rule and efficiency calculations include Supplement requirements.

Exam technique

For a four-mark comparison, aim for four separate, scenario-linked points. Pair advantages and limitations where possible. If the setting is remote, fuel transport and reliability may matter more than a generic national-grid point. If the question asks about environmental impact, answer with the specific impact rather than cost.

How this is examined

Core and Extended papers can ask candidates to identify generation methods and compare their advantages and disadvantages. Extended questions can also connect the resource to its original source, fusion in the Sun or efficiency calculations. Practical papers do not normally require a power-station experiment, but data-handling questions can place familiar graph or evaluation skills in an energy-resource context.