Energy resources
Discover where useful energy comes from, how each resource works, and how to compare choices using evidence rather than slogans.
Core: resource mechanisms and comparisons. Supplement / Extended: the Sun as the main source and fusion research (steps 6–7 and questions 13–14). This is Cambridge IGCSE, separate from Egyptian Baccalaureate / Thanaweya Amma and Year 3.
Two different questions
An energy resource supplies useful energy. Renewable asks whether nature replenishes it on a useful human timescale. Reliable asks whether a system can supply energy when needed. Renewable sources can vary, and stored finite fuels can provide controllable output.
Worked example
Wind may be plentiful over a year but weak on a particular evening. Coal can be stored for that evening, but using it depletes a finite resource and creates emissions. Neither fact alone decides the best system.
Think first: Does renewable mean pollution-free?
No. Biofuel combustion emits gases; reservoirs change habitats; manufacture and disposal matter for all technologies.
How each resource works
Resource cards and pathway check
Choose a resource, read its explanation, then select its broad pathway. The heat pathway is a simplified steam-system example; wave devices have several designs.
Fossil fuels · Non-renewable
Coal, oil and natural gas store chemical energy. In a steam power station, burning fuel heats water; steam turns a turbine connected to a generator. Fuels can also heat homes or power engines directly.
Strength and scale: Stored fuel supports controllable, large-scale output while fuel supplies and machinery are available.
Conditions and impacts: Finite fuel stocks; combustion releases carbon dioxide. Some fuels also release pollutants such as sulfur dioxide. Extraction, transport and construction have impacts too.
Changing resource resets your answer. This is learning practice, not a saved score. Read all ten cards to cover the full list.
Build a comparison answer
- Name both resources and their useful outputs.
- Choose the requested criteria.
- Give a fact, then its consequence for the stated place or time.
- Distinguish operation from construction, fuel supply and disposal.
- Give a conditional recommendation, not a universal winner.
Worked comparison: a sunny school needs evening electricity
PV uses the available sunshine without fuel combustion during generation, but supplies no electricity after sunset. Consider PV with properly sized storage or alternative supply for evenings, while checking cost, space and demand. “Sunny” alone does not guarantee continuous supply.
Worked explanation: geothermal and nuclear
Both can heat water and use steam to turn a turbine and generator. Geothermal uses underground heat and needs a suitable site; nuclear fuel releases energy in a reactor and leaves radioactive waste. The same generator mechanism does not mean identical heat sources or impacts.
Availability is not the same as demand
Can this interval meet demand?
A fictional town needs 100 kW. Each solar or wind unit is rated at 20 kW. For this teaching model only: sunny solar output is 100% of rating, cloudy is 25%, night is 0%; wind is full output in the selected windy condition and zero when calm. Hydro supplies a fixed 20 kW, assuming enough water. These invented conditions are not efficiency values, forecasts or a real grid design.
Actual outputs: solar 60 kW; wind 40 kW; hydro 20 kW. Demand: 100 kW.
Investigate: with three solar and two wind units, compare sunny, cloudy and a calm night. Can simply adding more solar units fix the night gap? Explain before changing sliders. Changing any control clears feedback.
Practise, then explain
Four multiple-choice questions, two numerical responses and eight written tasks. Questions 1–12 are Core; Questions 13–14 are Supplement / Extended only. Numerical answers are checked automatically; written answers use a self-assessment guide. The suggested marks are for this original practice, not an official Cambridge mark scheme.
Practice stays only while this page is open. Refreshing or leaving clears these responses. Copy useful written work into your notes before leaving.
Which statement correctly describes a coal-fired steam power station?
Optional hint
Separate heating, rotation and electrical output.
Source clarifications
The original PDF is unchanged. Some source answers say solar cells give no electricity “in cloud”; cloud or dust usually reduces output, not necessarily to zero. “Solar panels” means water heating in this syllabus, but everyday usage also includes PV. We name the technology explicitly.
Predictable tides are not constant supply. Hydro depends on water; geothermal and fuel stations have operating limits. No combustion during generation does not mean zero life-cycle impact. Wave devices and geothermal steam systems vary. The source’s “three parts after the boiler” wording is ambiguous: the full simplified chain is heat source → boiler/steam → turbine → generator → electrical output.
These are learning examples, not current cost rankings or engineering recommendations. Supplement follows the fusion-research objective without claiming a current commercial milestone.
Source alignment: supplied Physics-0625 Volume A, PDF pp. 118–125 / printed pp. 110–117, Figures 17.1–17.2; official Cambridge 2026–2028 syllabus, section 1.7.3. Original text, practice and hypothetical data. Original source-download access is preserved.