What energy is stored in fossil fuels, and what releases it?
Chemical energy, released by combustion.
Cambridge IGCSE (9–1) Physics 0972 (Extended) (2026–2028) · 1.7.3
Revise Cambridge IGCSE (9–1) Physics 0972 (Extended) (2026–2028) specification point 1.7.3, Energy resources, with free active-recall flashcards. Flip through the set or review every question and answer below.
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What energy is stored in fossil fuels, and what releases it?
Chemical energy, released by combustion.
Besides generating electricity, what can fossil fuel combustion provide directly?
Useful heat.
How does a fossil-fuel power station use combustion to generate electricity?
Combustion heats water in a boiler to produce steam. The steam turns a turbine connected to an electrical generator.
Why are fossil fuels non-renewable?
They are used much faster than they form, so supplies are finite.
What are two practical advantages of fossil fuels as an energy source?
They are widely available and can provide reliable, controllable power on a large scale.
How does burning fossil fuels contribute to climate change?
It releases carbon dioxide.
What can burning fossil fuels release besides carbon dioxide?
Air pollutants.
What environmental harm can fossil fuel extraction cause?
It can damage environments.
What type of energy do biofuels contain, and where does it come from?
Chemical energy from recently living material.
Besides generating electricity, what are two uses of burning biofuel?
Useful heating and, for some biofuels, powering engines.
How can burning biofuel generate electricity?
It heats water in a boiler to produce steam, which turns a turbine connected to a generator.
Under what condition can a biofuel be renewable?
When its source material is replaced as it is used.
What limits the availability and scale of biofuel use?
The supply of suitable material and land.
What advantage does stored biofuel have for power generation?
It can provide power when needed.
What two emissions-related effects can burning biofuel have?
It releases carbon dioxide and may cause air pollution.
What happens to carbon dioxide when replacement biofuel material grows?
The growing material takes in carbon dioxide.
Which three stages of the biofuel supply chain also have environmental impacts?
Cultivation, processing and transport.
How do wave-power devices generate electricity?
They transfer energy from the motion of water at the sea surface to a generator.
Is wave energy renewable or non-renewable?
Renewable.
Why is wave-power output not continuously reliable?
Available power varies with wave conditions.
What locations are needed for useful wave-power generation?
Suitable coastal or offshore locations.
How can wave-power devices be used to produce a larger output?
Individual devices can be combined.
What practical difficulties can arise when deploying wave-power devices?
Installation and maintenance at sea can be difficult.
What three aspects of the marine and coastal environment may wave-power devices affect?
Marine habitats, navigation and coastal views.
What combustion emissions do wave-power devices produce during operation?
None.
What does tidal power use to generate energy?
The movement or changing height of seawater as tides rise and fall.
How can moving seawater generate electricity in a tidal power scheme?
It turns turbines connected to generators.
How does a tidal barrage drive turbines?
It holds water so that a difference in water level drives the turbines.
Is tidal energy renewable or non-renewable?
Renewable.
How predictable are tides as an energy resource?
Tides are predictable.
How does tidal power output vary over time?
It changes through the tidal cycle and is not continuously available.
What limits where tidal power schemes can be built?
Suitable sites are limited.
What is a financial drawback of large tidal installations?
They can be costly.
What is an emissions advantage of tidal power during operation?
It can produce substantial power without combustion emissions.
What are three possible impacts of tidal schemes on the environment and human activity?
They may alter habitats, sediment movement and navigation.
What form of energy does water stored behind a hydroelectric dam have?
Gravitational potential energy.
How does released water drive electricity generation in a hydroelectric scheme?
It turns a turbine connected to a generator.
Why can hydroelectric power be renewable when managed sustainably?
The water cycle replenishes the water supply.
How does stored water affect the control of hydroelectric power output?
It allows output to be controlled and increased quickly.
What two water-related factors affect hydroelectric generation?
Rainfall and the amount of water in the reservoir.
What site condition is required for a large hydroelectric scheme?
A suitable site.
How much power can a large hydroelectric scheme supply?
Substantial power.
What are three possible impacts of hydroelectric dams and reservoirs?
Flooding land, displacing communities and altering river habitats.
Does operating a hydroelectric scheme involve burning fuel?
No.
Where does geothermal energy come from?
Thermal energy from the Earth's interior.
How can geothermal energy provide useful heating?
Hot water or steam from underground can provide heat.
How can geothermal energy generate electricity without burning fuel?
Underground steam, or steam produced by heating water with underground heat, turns a turbine connected to a generator.
Under what condition is geothermal energy renewable?
When heat and water are replenished sufficiently.
How consistently can geothermal energy supply power?
It can provide reliable power.
How do underground temperatures affect the availability of geothermal energy?
Availability is greatest where accessible underground temperatures are high, limiting suitable locations and the scale of generation.
How can geothermal installations affect the land?
They can disturb it.
What substances can geothermal installations release?
Gases or mineral-rich water.
How does a nuclear power station convert energy from its fuel into electrical power?
Fission heats water to produce steam. The steam turns a turbine connected to a generator.
Does a nuclear power station release carbon dioxide through fuel combustion during operation? Why or why not?
No. The nuclear fuel is not burned to provide heat.
Is nuclear fuel renewable or non-renewable?
Non-renewable.
What can nuclear power stations provide in terms of power supply?
Reliable, large-scale power.
What do nuclear power stations require in terms of construction and safety?
Substantial construction and safety measures.
What type of waste from nuclear power stations must be managed?
Radioactive waste.
What environmental consequences can nuclear power station accidents have?
They can have serious environmental consequences.
What energy transfer does a solar cell make?
It transfers energy from sunlight directly into electrical energy.
Which two devices are not needed for a solar cell to generate electricity?
A boiler and a turbine.
How can solar cells be combined for use?
They can be used individually or combined into larger arrays.
Is sunlight a renewable or non-renewable energy source?
Renewable.
Which three factors make solar-cell output variable?
Daylight, weather and location. Generation is unavailable at night.
Where can solar-cell arrays be installed at different scales?
On buildings or over larger areas.
What combustion emissions do solar cells produce during operation?
None.
Which stages of a solar cell’s life have environmental impacts outside operation?
Manufacture and disposal.
What land-use impact can large solar-cell installations have?
They use land.
How does a solar water-heating panel provide hot water?
It absorbs infrared and other solar electromagnetic radiation and transfers energy to water.
How does a solar water-heating panel differ from a solar cell in its useful output?
A water-heating panel provides direct heat; a solar cell generates electricity.
Is the solar radiation used for water heating renewable?
Yes, solar radiation is renewable.
What four factors limit the useful heat available from a solar water-heating panel?
Daylight, weather, location and collection area.
When might a solar water-heating system need another heat source?
When solar input is insufficient.
How do the environmental impacts of operating a solar water-heating panel compare with those of making and installing it?
Operation produces no combustion emissions, but manufacture and installation have environmental impacts.
Why is the Sun the ultimate energy source for wind?
Uneven solar heating of Earth’s surface contributes to air movement.
How does a wind turbine generate electricity?
It transfers energy from moving air to a generator, which produces electricity.
Is wind a renewable energy source?
Yes, wind is renewable.
Why is wind-power output intermittent?
Wind speed varies.
What location constraint affects wind-power output?
Output depends on finding suitable locations.
How can wind turbines be arranged?
They can be used individually or grouped into large wind farms.
Where can wind farms be located?
On land or offshore.
What combustion emissions do wind turbines produce during operation?
None.
What three environmental effects can operating wind turbines have?
They can affect landscapes, create noise and harm wildlife.
What environmental impact can occur before wind turbines operate?
Their construction and installation can have environmental impacts.
How is the energy efficiency of a process calculated?
How can efficiency be calculated using power?
What happens to the input energy that is not transferred usefully?
It is transferred in less useful ways, often to the surroundings as thermal energy.