The world is full of movement.
Trees move in the wind.
Aircraft fly in the air.
Ships sail on the sea.
People and animals move around.
None of these things can move without energy. Living things and machines need energy in order to work.
Where does energy come from?
Almost all energy comes from the sun.
The sun’s energy changes into other kinds of energy when it reaches the earth.
The sun’s energy is even in coal and oil.
Long ago, the sun gave its energy to plants and animals. When they died, their bodies slowly turned into oil and coal over millions of years.
Power stations then change the energy in coal and oil into electrical energy.
Without the sun providing energy, there would be no life on earth.
How do you keep cool in your house?
What sort of light do you use at night?
What appliances do you have in your home?
Anything that gives you heat or light uses energy.
Household appliances use energy. In your notebook, make a list of all the things in your kitchen that use energy.
What kind of energy do you think each appliance uses?
Most homes receive a supply of electricity. The electricity travels along cables and wires from a power station. At the power station, electricity is usually made from the energy released by burning fossil fuels, or by using nuclear fuel or waterpower.
Fossil fuels developed from the remains of prehistoric plants and animals.
These fuels include coal, natural gas, and petroleum, from which we get oil.
Wood, also, is often classified as a fossil fuel.
Besides electricity, fossil fuels are also used as a source of energy in our homes.
Wood, coal, and oil can be burned to give heat. Natural gas can be burned for heating and cooking.
Oil lamps and gasoline lanterns can be used as a source of light.
Other sources of energy in the home include solar energy and wind power.
Solar energy is energy from the sun, often gathered by solar panels. Solar energy can warm a house or heat up water. Wind power is often impractical unless there are strong, steady winds.
Fossil fuels are called nonrenewable sources
– of energy because, once they have been used up, they cannot be replaced. One day, all the coal, natural gas, and oil on earth may be used up. There will then be no more available.
Sources of energy that can be used over and over again are called renewable, or inexhaustible, sources.
Solar energy and forms of solar energy, like wind power and water power, are renewable energy sources. No matter how much we use them, there will always be plenty more.