🌍 Energy Sources and Conservation of Energy

1. The Sun is our primary source of energy as almost all of the energy we use comes directly or indirectly from it.

2. Energy is needed by living things to carry out life processes.

3. Primary energy sources refer to natural sources of energy such as the Sun, fossil fuels, wood, wind and hydropower (power from moving water). The three fossil fuels are coal (solid), oil (liquid) and natural gas (gas).

4. Renewable sources of energy are infinite as they are continuously replenished by nature and will not run out.

5. Non-renewable sources of energy are finite as they can never be replenished and will run out one day.

6. Classify the following energy sources:

• (a) Wind — renewable / infinite
• (b) Oil — non-renewable / finite

1. Solar energy refers to the light energy and heat energy that we obtain from the Sun. It is an important renewable source of energy.

2. Plants get light energy directly from the Sun to make food. The energy conversion is: light energy → chemical potential energy. Animals that eat the plants get the energy indirectly from the Sun.

3. Solar cells / batteries are used to power things such as solar water heaters, solar calculators, satellites and even solar cars. The energy conversion is: solar energy → electrical energy.

4. Solar panels that contain solar cells convert solar energy into electrical energy. Solar panels that contain water pipes convert solar energy into heat energy.

5. Fossil fuels, hydropower and wind energy are energy sources that come indirectly from the Sun.

1. Wind, which is moving air, possesses kinetic energy. It is a renewable / infinite source of energy because it is non-finite and will never run out!

2. Windmills make use of wind energy to rotate its blades and grind wheat.
Energy conversions:
kinetic energy (from moving air) → kinetic energy (of blades) → kinetic energy (in gears) → kinetic energy (of grindstone)

3. Wind turbines make use of wind energy to rotate its blades or rotors and generate electricity.
Energy conversions:
kinetic energy (in moving air) → kinetic energy (of rotors) → kinetic energy (in turbines) → electrical energy (from generator)

1. Hydroelectricity is electricity generated using moving water. Like solar energy and wind energy, hydroelectricity is renewable / infinite as it will never run out.

2. Hydroelectric power stations use a dam to trap a reservoir of water. This stored water is allowed to flow down through the dam at high speed. The moving water rotates a turbine that is attached to a generator.

3. The energy conversion in hydroelectric power:
potential energy (in reservoir of water) → kinetic energy (of running water) → kinetic energy (of rotating turbines) → electrical energy (generator)

1. Fossil fuels such as oil, coal and natural gas are obtained from underground. They are formed from the remains of dead organisms that lived hundreds of millions of years ago.

2. Fossil fuel is non-renewable / finite because it cannot be replenished.

3. Fossil fuels are burnt to cook food, run vehicles and generate electricity.
Energy conversion when fossil fuels are burnt:
potential energy → light energy + heat energy

4. A fossil fuel power station uses coal, oil or natural gas to boil water. The steam generated then moves a turbine that is attached to a generator.
Energy conversions:
potential energy (in fuel) → heat energy (from burning fuel) → heat energy (water → steam) → kinetic energy (of rotating turbine) → kinetic energy (generator) → electrical energy from generator

5. The power stations in Singapore burn coal which is imported / bought from other countries.

1. Conservation of energy refers to methods and technologies used to save energy resources in order to have a more positive impact on the environment.

2. Conservation of energy has been made mandatory in Singapore through the 'Energy Conservation Act'. Conservation of energy is needed to prevent fossil fuels from running out too fast, to reduce air pollution and global warming.

3. One way to conserve energy would be to use more renewable / alternative / infinite energy sources such as solar energy, wind energy and hydropower.