Renewable vs. non-renewable?

Renewable energy comes from sources that can be renewed or will never run out. This includes energy from on-going natural phenomena such as wind, sunlight, tides, gravity and geothermal heat (e.g. hot springs from deep underground).

These sources of energy are considered to be kinder to the environment. Often called ‘green’ energy, they don’t produce harmful greenhouse gases when used.

Non-renewable energy sources are those that cannot be replaced in a short amount of time when they have been used. Also known as fossil fuels, they take millions of years to form. So, in effect, when they're gone, they're gone! 

Coal, natural gas and crude oil are all examples of non-renewable energy sources. Australia, and the rest of the world, currently gets most of its energy from non-renewable sources, but that is slowly changing.


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CO2: good or bad?

It’s natural

Carbon dioxide, or CO2, is a colourless, odourless gas that exists in the Earth’s atmosphere. It’s a natural product – plants need it for photosynthesis, we breathe it out, animals release it when they decompose, and fires and volcanoes emit CO2, too.

It’s warming

Despite the bad rap that CO2 has, we actually need it in the atmosphere to keep the Earth warm. Along with other greenhouse gases, CO2 helps to keep the Earth’s surface and the atmosphere at the right temperature for plants to grow, animals to survive, and for us to live comfortably.

It’s increasing

The main problem with CO2 is that there’s now too much of it in our atmosphere due to human activity. With increasing amounts of this greenhouse gas in the atmosphere, more heat from the sun is trapped – causing global warming.

Why is there too much?

Humans are responsible for a lot of CO2 emissions. Human-generated sources of CO2 include transport, electrical power, industry and even home power usage. All these activities release excessive amounts of CO2 into the atmosphere.

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A NASA computer model gives a new look at how carbon dioxide travels around the globe.

The enhanced greenhouse effect


Large amounts of carbon dioxide are released when we burn fossil fuels.


More heat from the sun is trapped in the atmosphere.


The Earth’s surface temperature and atmospheric temperature rise.


The resultant global warming changes the Earth’s weather patterns, landscapes and even where people can live.

A short video explaining the enhanced greenhouse effect.

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Wrap up


Renewable energy sources like solar, wind and hydro are less harmful to the environment than non-renewable energy sources like coal.


We need some carbon dioxide in the atmosphere to sustain life on earth, and it is produced naturally through things like respiration, combustion and decomposition.


When we burn fossil fuels to make electricity, harmful levels of carbon dioxide are emitted into the atmosphere.



The enhanced greenhouse effect is caused by the excess carbon dioxide and other greenhouse gases in the atmosphere, which traps the heat from the sun. This causes global warming.