1.8Motion, Forces and Energy
Energy Sources — Cambridge IGCSE Physics 0625 Revision Notes & Topical Questions
15 min read 22 parts Lesson 83 of 91 Unit quiz
Lesson summary
1.8 Energy Sources (Part 1) — IGCSE PHYSICS notes: Explain how the Sun supplies most energy resources and evaluate solar cells, solar panels and wind turbines.Transfer to Earth — the Sun transfers energy to Earth by electromagnetic radiation, mostly visible light and infrared.The…
- Indirect solar resources
- Resources not from the Sun
- How they work
- Low energy density
- Improvements
- Solar furnaces
Part 1 of 7The Sun as the source of most resources
The Sun as the source of most resources
Transfer to Earth
- Transfer to Earth the Sun transfers energy to Earth by electromagnetic radiation, mostly visible light and infrared.
- The energy reaching Earth in one hour equals the world's energy use for one year.
Indirect solar resources
- Indirect solar resources most energy resources on Earth come indirectly from the Sun.
- The Sun heats the atmosphere, causing wind and waves.
- Evaporated water falls as rain and fills reservoirs.
- Plants grown with sunlight form the basis of biofuels and fossil fuels.
Resources not from the Sun
- Resources not from the Sun geothermal, nuclear (elements in the Earth's crust) and tidal (mainly the Moon's gravity).
- (heat from the Earth's core)
Part 2 of 7Solar cells
How they work
- How they work photovoltaic cells made of semiconducting materials transfer energy from sunlight and produce a current.
- Many cells connected together supply homes, small businesses, communication devices and satellites.
- Electricity can be stored in batteries for later use.
Low energy density
- Low energy density solar energy is spread thinly, so large collecting areas are needed.
Improvements
- Improvements better technology and large-scale manufacture have made cells cheaper and more efficient.
Part 3 of 7Solar panels and furnaces
Water is pumped from a tank through small pipes in the solar panel.
- Infrared radiation from the Sun heats the water as it flows through the pipes.
- The warmed water returns to the tank at a higher temperature.
- It may be heated further to reach the temperature wanted, such as for a shower.
Solar furnaces
- Solar furnaces large curved mirrors focus the Sun's rays onto a small area to boil water, producing steam to turn turbines.
Part 4 of 7Evaluating solar power
| Solar cells and panels | Advantages | Disadvantages |
|---|---|---|
| Supply | Renewable, the Sun will not run out | Intermittent, none at night and reduced in poor weather |
| Environment | No carbon dioxide or other greenhouse gases when operating | Large farms are needed for large output |
| Cost | No fuel cost, low running and maintenance cost | Initial installation cost |
| Location | Work in remote places without a grid, and roofs save ground space | Lower power output than mains, so a battery recharges slowly |
Part 5 of 7Wind energy
Energy chain
- Energy chain the kinetic store of the wind transfers mechanically to the turbine, then to the generator, and electrically to the grid.
Advantages
- Advantages wind power is renewable and clean.
- Wind is renewable and has no fuel cost.
- It gives no carbon dioxide, sulfur dioxide or acid rain when operating.
- Offshore sites are possible.
Disadvantages
- Disadvantages wind power has several drawbacks.
- Wind is unreliable because it can be too weak or too strong.
- Each turbine gives little power, so wind farms are needed.
- Offshore turbines are hard to maintain and can disrupt shipping.
Part 6 of 7More about solar energy and the Sun
More about solar energy and the Sun
Types of solar device
- Types of solar device solar cells make electricity and solar panels heat water.
Same Sun, different forms
- Same Sun, different forms wind and waves come from solar heating of the atmosphere, but tidal power does not.
Part 7 of 7More from the specification
1Renewable vs non-renewable energy resources
- Renewable energy sources naturally replenish on a human timescale, whereas fossil fuels and uranium are finite.
- (solar, wind, hydroelectric)
2Nuclear fission power generation
- Controlled fission of uranium-235 nuclei inside nuclear reactors releases thermal energy used to boil water, produce steam,
- and drive electrical turbines.
3Hydroelectric and pumped storage schemes
- Gravitational potential energy of elevated water reservoirs is converted into kinetic energy and electrical power via hydraulic turbines.
4Fusion
- Joining of light nuclei into a heavier one.
5Hydroelectric
- Electricity from water flowing down from a high reservoir.
6Global warming
- Rise in the average temperature of the Earth.
7Hydroelectric power
- Electricity generated from water flowing down from a reservoir.
8Nuclear fusion
- Joining of light nuclei to form a heavier nucleus, releasing energy.
Key terms
| Term | Meaning |
|---|---|
| Renewable resource | A resource that is replenished at the same rate as it is used. |
| Solar cell | A device that transfers sunlight to electricity. |
| Solar panel | A device that uses sunlight to heat water. |
| Energy density | The energy available per unit mass or area of a resource. |
| Intermittent | Not continuously available. |
| Wind turbine | A machine in which wind turns blades connected to a generator. |
Avoid these mistakes
1
Giving "cheap" or "clean" as an advantage with no explanation — say why, such as "no fuel cost".
2
Thinking all energy resources come from the Sun — geothermal, nuclear and tidal do not.
3
Saying solar cells and solar panels do the same thing — cells make electricity and panels heat water.
4
Forgetting that wind farms also have environmental costs such as disrupting shipping.
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