1.5.9Motion, Forces and Energy
Energy from Fuels — Cambridge IGCSE Co-ordinated Sciences 0654 - Physics Revision Notes & Topical Questions
5 min read 8 parts Lesson 32 of 36
Section 1 of 8Thermal power stations
Thermal power stations
A fuel is a material that stores energy which can be released in a useful form.
Steps in a thermal power station:
- The fuel releases energy, which is used to heat water.
- The water boils to form high-pressure steam.
- The steam turns a turbine (kinetic energy).
- The turbine turns a generator, which produces electrical energy.
- The steam is cooled and condensed and the water is reused.
Waste heat goes to the surroundings, often through cooling towers.
Section 2 of 8Fossil fuels
Fossil fuels
- Fossil fuels coal, oil and natural gas, formed over millions of years from the remains of living things.
They store chemical energy that is released when they are burned.
Efficiency
- Efficiency a fossil-fuel power station is typically 35% to 60% efficient, with the rest wasted as thermal energy.
Advantages:
- A concentrated energy source.
- Stations can run continuously and respond to demand.
- Established technology and relatively cheap, especially gas.
Disadvantages:
- Non-renewable, so they will run out.
- Burning gives carbon dioxide, a greenhouse gas that contributes to global warming.
- Coal also gives sulfur dioxide, which causes acid rain, and particles.
- Mining and drilling damage the environment and oil spills harm wildlife.
Section 3 of 8Biofuels
1
Biofuels are made from recently living material, such as ethanol from sugar cane, biodiesel from plant oils, and wood or plant waste.
2
They store energy collected by plants from sunlight through photosynthesis.
3
Advantages:
- Renewable because new crops can be grown.
- Roughly carbon-neutral, as the carbon dioxide released on burning was absorbed as the plants grew.
4
Disadvantages:
- Large areas of land are needed, which may compete with food crops or cause deforestation.
- Crops need water and fertiliser.
- Significant energy may be used in making them.
Section 4 of 8Nuclear fission
1
Fuel is uranium or plutonium, and the energy store is nuclear energy.
2
A neutron splits a large nucleus in fission, releasing energy mainly as kinetic energy of the fragments, which heats the reactor.
3
Neutrons released split further nuclei, giving a controlled chain reaction.
4
The heat makes steam, as in other thermal stations.
5
Advantages:
- A very large amount of energy from a small mass of fuel.
- No carbon dioxide released in operation.
- Reliable, continuous output.
6
Disadvantages:
- Radioactive waste that must be stored safely for thousands of years.
- High building and decommissioning costs.
- Risk of accidents with serious consequences.
- Uranium is a finite resource.
Section 5 of 8Comparing power stations
Compare fuels by energy per kilogram, reliability, cost, emissions, waste and renewability.
Fossil fuels and nuclear give steady power on demand, unlike intermittent wind and solar.
A gas station is quick and cheap to build and can be switched on rapidly, but it emits carbon dioxide and uses a finite fuel.
A nuclear station has high building and decommissioning costs but emits no carbon dioxide in use and runs steadily.
A realistic electricity system uses a mix of sources.
Kilowatt-hour
- 1 kWh is the energy transferred by a 1 kW device in 1 hour, which is 3 600 000 J.
Section 6 of 8More from the specification
1Solar Cells vs. Solar Heating Panels
- Photovoltaic cells generate electricity directly from incident solar radiation via the photoelectric effect,
- whereas solar panels absorb thermal energy to heat domestic water supplies.
2Hydroelectric and Tidal Power
- Hydroelectric schemes store gravitational potential energy of water held behind dams at height,
- while tidal energy harnesses the periodic gravitational movement of ocean water driven by Earth-Moon interactions.
3Geothermal Energy Supply
- Heat energy originating from radioactive decay deep within the Earth's interior provides a continuous, weather-independent steam supply to drive turbine generators.
4Nuclear Fusion and Atmospheric Emissions
- Nuclear fusion combines light nuclei into heavier nuclei to liberate immense energy without producing harmful greenhouse gases that pollute the atmosphere.
5Solar Cells vs. Solar Heating Panels
- Photovoltaic cells generate electricity directly from incident solar radiation via the photoelectric effect,
- whereas solar panels absorb thermal energy to heat domestic water supplies.
6Hydroelectric and Tidal Power
- Hydroelectric schemes store gravitational potential energy of water held behind dams at height,
- while tidal energy harnesses the periodic gravitational movement of ocean water driven by Earth-Moon interactions.
7Geothermal Energy Supply
- Heat energy originating from radioactive decay deep within the Earth's interior provides a continuous, weather-independent steam supply to drive turbine generators.
8Nuclear Fusion and Atmospheric Emissions
- Nuclear fusion combines light nuclei into heavier nuclei to liberate immense energy without producing harmful greenhouse gases that pollute the atmosphere.
9Geothermal
- Energy from hot rocks underground.
10Fusion
- Joining of light nuclei into a heavier one.
11Hydroelectric
- Electricity from water flowing down from a high reservoir.
12Solar panel
- A device that uses sunlight to heat water.
13Solar cell
- Device that converts light energy directly into electrical energy.
14Geothermal energy
- Thermal energy from hot rocks inside the Earth.
15Hydroelectric power
- Electricity generated from water flowing down from a reservoir.
16Nuclear fusion
- Joining of light nuclei to form a heavier nucleus, releasing energy.
Section 7 of 8Key terms
| Term | Meaning |
|---|---|
| Fossil fuel | Coal, oil or natural gas formed from ancient living things. |
| Biofuel | Fuel made from recently living plant or animal material. |
| Fission | Splitting of a large nucleus releasing energy. |
| Chain reaction | Neutrons from one fission trigger further fissions. |
| Greenhouse gas | Gas such as carbon dioxide that traps thermal radiation. |
| Turbine | Machine with blades turned by steam or moving fluid. |
Section 8 of 8Exam technique
1
Saying fossil fuels are made of Sun — they store chemical energy from ancient plants and animals.
2
Believing nuclear power stations produce carbon dioxide from the reactor.
3
Treating biofuels as free of environmental impact.
4
Saying nuclear fuel is renewable.
5
Leaving out the turbine and generator steps in electricity generation.
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