About energy

Energy is essential to life - from helping plants grow and cooking our food to powering our cars and appliances, drying our clothes and helping us to move. Look at all the machines and appliances that are operating around you; they all use some form of energy. Can you imagine your life without them?

Did you know that energy can come from primary and secondary sources?

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Primary sources of energy

Primary sources of energy are those which are found in nature. This includes coal, natural gas, water, wind and biomass. The Sun is the original energy source for these primary energy sources. Without the Sun, these other energy sources could not exist.

Did you know that some energy on earth does not come from the Sun originally? Heat energy from the centre of the earth rises up through gaps (hydrothermal vents) in the sea bed. Warm gaseous substances provide energy for bacteria, and in turn an entire underwater ecosystem is created including giant tube worms and clams.

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Secondary sources of energy

Secondary sources of energy are produced when primary sources are converted into forms of energy that can be more easily used, such as electricity.

Electricity is the most widely used and fastest growing form of secondary energy. In Australia, it's mostly generated in power plants that burn fossil fuels to create steam. This steam then powers machines that generate electricity. The most commonly used fuel in Australia is coal (a non-renewable energy source) because we have a large natural supply. Electricity can be generated by a variety of sources though, including several renewable energy sources.

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Energy: The facts

Electricity is measured in watt-hour (Wh). For example, light bulbs come in different watt (W) ratings. A duller bulb might have a rating of 40W and a brighter bulb a rating of 100W.

The amount of electricity consumed by appliances is worked out per hour, so that a 40W light bulb that is turned on for an hour, uses 40 Wh of electricity.

Electricity bills give the total number of kilowatt hours (kWh) of electricity used by a household over several months.

More about light globes

Do you know the difference between incandescent and compact fluorescent light (CFL) globes? You will have seen the twisting curved or folded shapes of CFL globes, which are quite different to the rounded ‘balloon-shaped’ incandescent globes. Incandescent globes contain a metal filament. Electricity heats the filament until it glows white — giving out light. Unfortunately this makes these globes inefficient; because not all of the electricity is converted to light (much is ‘lost’ as heat).

CFL globes use a different method to produce light. Electrons from the electricity cause gases trapped inside the tube to gain more energy, and they give off photons (particles of light energy). The photons hit a coating of phosphor lining the tubes and the phosphor lights up (fluoresces).

A typical CFL uses around 75 — 80 per cent less electricity and lasts between eight and fifteen time longer than an incandescent light globe. Although CFL’s have a higher cost, they last longer than incandescent globes.

Renewable or non-renewable energy?

Do you know the difference between renewable and non-renewable energy - and does it matter which one we use?

Renewable energy is energy which 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).

Non-renewable energy sources are those that cannot be replaced in a short amount of time when they have been used. Deposits of coal take millions of  years to form. So, in effect, when they're gone, they're gone! Coal, natural gas and crude oil, all of which are fossil fuels, are examples of non-renewable energy sources.

Australia, and the rest of the world, currently gets most of their energy fromnon-renewable sources, but that is slowly changing.

Star ratings of appliances

You may have noticed ‘Energy Rating’ labels on electrical appliances. The system is based on the amount of energy the appliance consumes when it is in use. There is an energy consumption box that tells you how much energy the appliance uses in kWh. A number of stars (from one to six) are provided; with the more stars meaning the appliance is more energy efficient, has lower running costs and produces less greenhouse gases.

Stand by power

Did you know that when your TV is switched on at the wall, but you are not using it, that the TV is still consuming electricity? Many household appliances, such as TVs, microwaves, stereos, computers, electric toothbrushes and mobile phone chargers, are left on 24 hours a day.

Even when they are not being used they may be running on standby power. In offices, between 40 and 89 per cent of the total energy use from computer equipment is due to this ‘standby power’. So, switching appliances off at the power point when you are not using them saves energy.

Energy transformations

When electrical energy is converted to heat and light energy is an incandescent light globe, this is an example of a series of energy transformations. Energy can appear in a number of different forms, including kinetic (movement), heat, sound, light, and potential (stored) energy. As for the light globe, heat is often produced as a by-product of energy transfer, and reduces the efficiency of electrical appliances.

Energy and the environment

The use of non-renewable energy sources has environmental impacts that we all need to think about. The most significant of these is greenhouse gas emissions.

Have you heard of carbon dioxide? It's a colourless, odourless gas that is naturally present in small amounts in the Earth's atmosphere. Carbon dioxide is important for many natural processes, such as plant photosynthesis.

Most carbon dioxide emissions come from natural sources such as:

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When we breathe out we exhale carbon dioxide

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Plants and animals release carbon dioxide into the atmosphere when they decompose.

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Carbon dioxide is released as a by-product of fires. This can happen during bushfires, or when a farmer is burning crop waste. Volcanic eruptions also release carbon dioxide into the atmosphere

Because they're natural processes we can't really do anything about these carbon emissions.

These greenhouse gas carbon emissions contribute to the greenhouse effect. The greenhouse effect is a natural warming process. When incoming energy from the Sun reaches the Earth’s surface, some of the energy is absorbed, warming the surface.

Some of the Sun’s energy is radiated back into space, but some of this is radiated energy is trapped in the atmosphere by greenhouse gases. The greenhouse gases include carbon dioxide, methane and water vapour. This trapped energy further warms the earth’s surface and the atmosphere.

The other source of carbon dioxide emissions is human activity.

Human-generated sources of carbon dioxide include:

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Vehicles, planes, ships

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Electric power

Generated by burning fossil fuels

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Industries such as steel, paper and concrete manufacturing produce large amounts of carbon dioxide

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Home power use

Including activities like cooking on a gas stove or BBQ and using lawn mowers

These are the activities we can do something about.

So, why is it a problem if increased amounts of carbon dioxide are released into the atmosphere?

When large amounts of carbon dioxide are released into the atmosphere it causes more heat from the Sun to become trapped in the atmosphere, resulting in an increase in the Earth's surface temperature and in the temperature of the atmosphere. This is known as the enhanced greenhouse effect'.

Why is an enhanced greenhouse effect a problem? The increase in the temperature of the atmosphere caused by the enhanced greenhouse effect is called ‘global warming’. If the temperature of the Earth's atmosphere rises, it may cause changes in weather patterns (longer droughts, more storms or heavy rains), landscapes (melting ice caps and rising sea levels) and even where people are able to live (long droughts have affected food supplies). Such changes are referred to as climate change.

However, it IS possible to reduce the amount of carbon dioxide in the atmosphere.


Solar energy is energy generated by the sun. Interestingly, energy from the sun is the original source of all energy on Earth!


Solar energy is used in three main ways:


Passive Solar

This involves using the sun for light and heat, including warming rooms in winter, drying clothes and sun-drying foods, such as prunes, apples, apricots and sultanas. Many houses and other buildings are designed to make the best use of passive solar energy by including features such as eaves to keep summer sun out and winter sun in, north-facing windows to maximise solar gain in winter, and insulation to reduce heat loss from a house in winter and to minimise heat gain in summer.

Thermal Solar

Thermal solar technology involves collecting heat from the sun and storing it for later use. Solar water heating is a good example of thermal solar energy.

Photovoltaic Solar (PV)

Photovoltaic cells (solar cells) are used regularly on rooftops of homes and other buildings to supply them with electricity.

This happens as follows:

  1. Energy from the sun is captured by the solar cells, where it is converted into an electrical current.
  2. The electricity is fed into a power box, which is located on the house (or other building).
  3. From the power box the electricity can be used for energy needs, such as lighting or heating.


The sun is a fantastic source of energy. It is clean, sustainable and can be used without any complicated equipment. Next time you are cold, don't turn on a heater - stand out in the sun and warm up!

People have always used the sun as a source of energy - to warm themselves, grow crops, and to dry things like clothes and food.

Environmental factors such as the weather, time of year and location all influence the amount of sunlight available, but solar energy can be harnessed at any time of the year.

Did you know that solar energy can provide about 60 per cent of the energy needed to supply your house with hot water?

There are three components of a household solar power system. They are the solar panels, inverter (converts the direct current from the cells to alternating current) and two-way electricity meter (allows surplus power from the solar cells to be directed into the electricity grid).

Would you believe that PV solar technology was first used on a Russian satellite in 1957 to provide power while it was in space?


Wind is an amazing source of energy. It is powerful, naturally available and will never run out. Wind energy can be used to generate electricity through wind turbines. Have you ever seen a wind turbine? They work in much the same way as windmills do, but are much taller, with long blades similar to aeroplane propellers.

Turbines generate electricity in the following way:

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1The wind caused the blades to turn, rotating a generator (located at the top of the turbine) which creates electricity.

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The electricity travels to a substation.


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The electricity is transferred from the substation to the electricity grid, travelling along wires on power poles and into your home.

Wind power: The facts

A group of wind turbines located together is called a wind farm. Have you ever seen one? They look amazing!

Modern wind turbines start generating power at low wind speeds - around 14 kph. While the turbines can operate in a range of conditions, sometimes they need to be shut down in storms or stronger winds (over 90 kph), because very high wind speeds can damage their blades.

Denmark was one of the first countries to use wind power to make large amounts of electricity and is now one of the largest producers of wind-generated electricity in the world.

Australia has a good wind resource, so we have opportunities to harness the power of the wind.

Just one average two-megawatt wind turbine can produce enough energy to power more than 850 homes a year!

Wind power can help us reduce our greenhouse gas emissions because every one megawatt hour of wind energy generated may avoid producing one tonne of greenhouse emissions from traditional sources of electricity.

What is hydro energy?

Hydro energy is energy captured from moving water that is converted to electricity through a process in a hydroelectric dam.

Hydroelectric dams work in the following way:

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Water from a dam is channelled through pipes into a turbine, where it turns the turbine blades.

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The blades rotate a generator creating electricity and the excess water is released back into the water system.

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The electricity is transferred from a substation, through the electricity grid, to your home.

Hydro energy: The facts

Have you ever heard of The Snowy Mountains Scheme? It is a famous Australian hydroelectricity project. Located in New South Wales, it was built between 1949 and 1974.

The scheme diverts megalitres of water from melting snow and rain in the Snowy Mountains for irrigation west to the Murray and Murrumbidgee river systems. Hydroelectricity is produced by using water from 16 major dams, 7 power stations, 145km of tunnels and 80km of canals.

Waves are a source of hydro energy. Have you ever been body surfing, or been caught in a wave at the beach? If you have, you know that waves can be very powerful.

Finding a practical way to turn wave energy into power has proven to be tricky. Many ways of harnessing wave power have been suggested, mostly involving using the movement of waves to turn generators.

In 1895 the street lights in Launceston, Tasmania, were powered by generators turned by the flow of the South Esk River.

Tides are another source of hydro energy. Every day, the pull of the moon and the sun's gravity move the oceans back and forth. Many ideas have been proposed to harness the power of the tides, but few have resulted in any commercial production of power. Can you think of any examples?

People in the 1880s used the power of falling or running water to turn dynamos and make electricity.

What is biomass energy?

Biomass is the name given to the total mass of organic material on Earth. ‘Organic’ means the material from all living plants and animals (including humans). Did you know that you can get energy from plants and animals? This type of energy is called biomass energy. You might also have heard it being called 'biofuel'.

Biomass can be used to produce electricity in the following ways:

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Organic material (such as plant cuttings or land fill) is fed into a drying chamber via a conveyor belt.

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Once dried, the material moves into a combustion chamber where air is added to assist it to burn.

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As the material is burnt gas is released and collected.

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The gas is passed through a pipeline where it is used to power turbines and generate electricity.

Biomass energy: The facts

Have you ever heard of ethanol? It is a form of alcohol made from corn, sugar cane, or sugar beet. These plants are used because they have a high sucrose content. Tiny organisms feed on the sucrose and convert it to ethanol. Ethanol is most commonly blended with petrol and used to power cars and other vehicles. You can see this fuel for sale at petrol stations today.

Imagine this! You find a lunchbox at the bottom of your school bag that has been there for weeks and open it to find a rotting sandwich or piece of fruit and it smells bad. What you smell is methane gas. As plants, and other matter, decompose the tiny microbes living on them give off methane gas. If the gas is able to be collected it can be used as a fuel.

People are helping too! Gases collected from human sewage are being used to produce energy. In the Sydney suburb of Cronulla, the water authority is capturing methane from treated sewage waste and using it to generate electricity. Similar plants operate in other major treatment works across Australia.

Capturing and using methane is important because it is a strong greenhouse gas. Methane gas has 21 times the greenhouse gas effects of carbon dioxide so it is captured and burned (combusted) to release energy (producing carbon dioxide) rather than being released directly into the atmosphere.

Oils from plants and animals can be used as biofuels. During the last century oil from the blubber of giant sperm whales was used in lamps for lighting before electric light was widely available.

Using solid waste to generate energy can be a great waste management solution. If waste products are not burnt they rot and give off methane which is not good for the environment.

Sugar and corn are not only foods; they can also be grown to make biofuels.

BE energy smart

There are many things we can do to reduce the amount of energy used in our homes, and to reduce gas emissions that contribute to the enhanced greenhouse effect: we can all be ‘energy smart’.

How can you be energy smart?

Did you know that an average Australian household produces approximately 14 tonnes of greenhouse gases each year? This means that Australia's average emissions per capita are amongst the highest in the world.

What can you do about the enhanced greenhouse effect, global warming and climate change? You can't live without energy, but you can try to manage your use and utilise renewable sources whenever possible.

In the past, coal has been a widely used source of energy to generate electricity, but it is not a sustainable source of energy. It is an example of a non-renewable energy source. Renewable energy sources are those found in an unlimited supply. These include solar, wind, biomass and hydro. However, we should attempt to use these both non-renewable and renewable resources wisely and there are many ways to be energy smart.

Listed below are some simple things you can do to become energy smart:

Turn it off

You can be energy smart by simply turning off appliances at the power point when you are not using them. This reduces the amount of standby power used.

Switch to low-energy light bulbs (you should still turn them off when you leave a room).Ask your local council if they have a light bulb exchange program.

Be clean

Clean energy sources are naturally occurring and do not pollute the atmosphere. There are many choices you can make that take advantage of clean energy sources:

You can use your own energy by walking or riding a bike instead of being driven in a car. If you can't walk, you could catch public transport, or ask your parents to try carpooling, as more people in one car means less cars on the road.

Who does the washing at home? Encourage them to use solar energy from the Sun to dry the clothes on a clothesline instead of using a machine dryer.

Use natural sources of light and heat. Try opening your curtains instead of turning on a light and wearing an extra layer of clothes (or taking one off) instead of using the heater or air conditioner.

When doing a load of washing try to use cold water, as this uses less energy than hot water. Also try to make sure you only wash when you have a full load.

Only run your dishwasher when it has a full load - this can help to save water and energy.

Use the natural energy from the Sun to dry your clothes whenever possible. If you have to use the machine, make sure you have a full load and use a sensor type dryer if possible.

Warm up your food in the microwave - not only is it quicker but it uses less energy than an oven.

If you are cooking in the oven don't open the door too often. Every time the door is opened the oven loses 14-20°C, so cooking takes longer and the oven uses more energy to heat up again.

Buy local

Think about how much energy is used to produce and transport the products you buy.

Now, think about the fresh foods you eat. It takes energy to grow, harvest, package and transport the food to the shops where you buy it.

You can help save the energy used in transporting products by buying locally produced products which use less energy to get to you (i.e. the distance the product has to travel by road, air or sea, is much less for local products than it is for products from distant places).

Why not try going to a local farmer's market where you can buy your food straight from the people who grew it?

Feed yourself

Many families and schools are now creating their own vegetable patches and kitchen gardens.

Growing your own food can be healthier and means that food does not have to be transported to you.

Reduce, reuse and recycle

How many times have you thrown something away that could be reused or recycled? If we did not buy everything new, we could save an enormous amount of energy. You could also swap things with your friends and recycle as much as possible.

You may not think that these little changes can make a difference, but if everybody makes them it could help reduce our greenhouse gas emissions. The environment and future generations will thank you!