Sources of energy

• We are able to receive different forms of energy from various sources of energy.

• The Sun is the main source of energy as most of the energy that we use comes directly or indirectly from the Sun.

• Without the Sun, all living things would die.

Adapted from 2009 Marshall Cavendish International (Singapore) Private Limited

Sources of energy (renewable)

the Sun windrunning water

The above are renewable sources of energy. They are energy sources that will not run out.

• Sources of energy:

Sources of energy (non-renewable)

• Sources of energy:

Non-renewable sources of energy are energy sources that will run out once they are used up. Fuels are an example

of a non-renewable source of energy.

fuels

Energy from the Sun• Plants use light energy

from the Sun for photosynthesis.

• This energy is converted to chemical energy in the food made by plants.

• When Man and animals eat plants, they are indirectly using the energy from the Sun.

Energy from the Sun• Energy from the Sun can be converted to

electrical energy with the use of solar cells and solar panels.

water tanksolar panel

The solar panels trap solar energy to heat water or keep

homes warm.

solar panels

satellite

The solar panels in a satellite trap solar energy. This solar energy is then

changed to electrical energy to power the

satellite.

Energy from the Sun

• Other uses of solar energy

solar panel in a solar power station

solar panel in a solar car

© 2009 Marshall Cavendish International (Singapore) Private Limited

Energy from running waterEnergy from running water

• The Sun’s energy allows the water cycle to take place, ensuring the continuous supply of water.

• The energy from running water in rivers can be converted to electrical energy.

• Electrical energy that is generated from running water is called hydroelectric energy.

How is electricity produced in a hydroelectric power station?

2. When water rushes down through the dam, the potential energy in the water changes to kinetic energy.

1. In a hydroelectric power station, a dam is built across a river. The water from the river behind the dam has an enormous amount of gravitational potential energy.

3. The kinetic energy from the running water turns the turbine.

4. When the turbine spins, the generator produces electricity.

gravitational potential energy kinetic energy electrical energy

© 2009 Marshall Cavendish International (Singapore) Private Limited

Using energy from running water

Using energy from running water

A water-wheel, such as the one on the left, makes use of running waterto grind grains, pump water, and produce electricity.

• Wind is moving air and possesses kinetic energy.

• A wind turbine uses kinetic energy from the wind to generate electricity.

• When the wind spins the blades of the wind turbine, the generator will produce electrical energy.

• A windmill uses energy from the wind to pump water or grind grains.

Energy from the wind

blade

generator

wind turbines

Using energy from fuels

• Coal, oil and natural gas are fuels that store chemical energy.

• When the fuels are burnt, the chemical energy in them is changed to heat and light energy.

Using energy from fuels

• Fuels such as coal, oil and natural gas are non-renewable source of energy.

• They will run out one day.• To prevent the supply of

these fuels on Earth from running out too fast, we must learn to use energy wisely or use alternative sources of energy.

An oil rig drills for oil and gas under the sea floor.

Different types of power Different types of power stationsstations

What sources What sources of energy do of energy do these power these power stations use stations use to generate to generate electricity? electricity? Do these Do these sources sources derive energy derive energy from the Sun?from the Sun?