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Teachers Notes
What is Energy?
Energy is the ability to make something do work or change. Everything in the world involves the exchange of
energy. When we use energy we don’t create it or use it up, we convert one form of energy to make another.
The energy around us comes in many different forms:
Electrical
(electricity)
Fornmesrgy
of E
Mechanical
(motion)
Thermal
(heat)
Nuclear
(fission, fusion)
Radiant
(light)
All of these forms of energy are either
Chemical
(stored)
Sound
(motion)
potential or kinetic.
Potential energy is stored energy that has the ability to release into lower forms. When it is released this
is the kinetic or moving energy. There are many different ways to convert different sources of energy into
forms that are usable. For example when we burn a source of energy, such as wood, it generates heat.
This is a form of energy that we can use to keep us warm.
Fossil fuels take millions of years to form. The supply of fossil fuels is
limited and is not being replaced as quickly as we are using them, for this
reason we call them a non renewable resource.
We face two challenges when considering future energy use:
1. Conserve and efficiently use the remaining fossil fuel reserves
2. Find suitable alternatives of renewable energy sources.
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don’t waste
your energy!
s
e
c
r
u
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S ergy
of En
Sunlight
One of the most important sources of energy for us and our
planet is the sun. The energy from the sun is the source of
most of the energy found on earth. Here are some of the
many different sources of energy used today:
The light that comes to the earth from the sun is pure energy. Organic matter, such as plants,
convert solar energy into food to grow leaves, flowers and fruits. Animals that eat organic matter
convert the energy into body mass (helping them to grow). When plants and animals die the
stored chemical energy is is transformed into fossil fuels.
Food is the source of energy used by people and living things.
When the food humans eat is
digested the energy can be stored and later converted for the body to use. The body needs to eat
and process energy all the time so that it can continue working, playing and growing.
Vegetable and animal oils have played an important role in human history.
Olive, corn and
canola are some of the vegetable oils we commonly use for cooking. Jojoba oil, from the jojoba
bean is used for cooking, lubricating and also in lotions and soaps. Animal oils from whales,
seals and livestock were used in the past for lighting lamps, waterproofing and in cosmetics.
Today oils can even be used to power cars!
Wood is an organic plant material that has stored energy originally derived from sunlight.
When
trees are cut down and burned they release their energy in the form of heat. In the past wood
was predominantly used for cooking and heating. It continues to be used today as a heating
source for many homes and in some instances for making electricity.
Wind is an energy source originally generated from the sun.
As the sun heats up the earth the
warm air rises and cool air rushes in to fill the space. These currents circulate air masses around
the atmosphere. Wind turbines are used to harness this energy and convert it into electricity.
Wind is a great example of a renewable energy resource.
Water also originates from the sun. Through heating and cooling of air masses condensation
forms as clouds and is precipitated into our rivers, lakes and oceans. Wave, tidal and
hydropower are three different renewable technologies that put water to work to generate
electrical energy.
Uranium is used to generate electrical energy through a nuclear power plant.
Radioactive ore
is extracted from the ground as chemical energy then transformed to heat and electrical energy.
It is a highly efficient energy source however the radioactive waste is hazardous to living things.
The major problem with nuclear power is finding a suitable and safe method of disposing of the
toxic waste.
coal, oil and natural gas are sources of energy known as fossil fuels.
The stored chemical
energy is initially derived from plant and animal remains and the sun. When these fuels are
burnt at power stations they release carbon dioxide into the atmosphere. Carbon dioxide is a
major greenhouse gas and is contributing to global warming. Fossil fuels are a non-renewable
energy source. They take millions of years to form, and are not able to be replaced quickly.
energy &
fossil fuels
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Fossil Fuels
Fossil fuels are found deposited in rock formations. They formed between 50 to 350 million years ago when
decayed remains of ancient plants and animals were buried by sediments. Over time heat and pressures
within the earth chemically altered the sediments and remains leaving behind the products of coal, oil, and
natural gas.
Stages of Coal Formation
Coal was formed from the remains of ferns, trees and grasses that grew in swamps around 345 million years
ago. The plant material continued to decay in layers forming beds of peat, a soft brown substance that is
up to 30% carbon. Peat is the earliest stage of coal formation. Later, shallow seas covered the swamps
depositing layers of sand and mud over the peat. These sediments exerted pressure and over thousands
of years the chemical changes transformed the peat into lignite or brown coal which contains around 40%
carbon. Millions of years later, increasing pressure and heat changed the lignite into bituminous or soft coal
which contains around 66% carbon. Finally anthracite or hard coal that has over 90% carbon. Coal is mainly
used to generate electricity at power stations, however it is also used to produce fertilisers, drugs, dyes, soap,
tar, disinfectant and pesticides.
Oil and Natural Gas are also found in beds of sedimentary rock.
These sediments were deposited by shallow
seas millions of years ago. The remains of plants and animals living in the sea settled to the bottom and were
buried under layers of sediment. These layers were also subjected to heat and pressure transforming into
beds of rock. The plant and animal remains went through a process of slow chemical change forming pockets
of oil and natural gas. Oil is mainly used to power motor vehicles and small amounts are used at power
stations. Other uses for refined oil are medicines, plastics, glues, detergents, cosmetics and paints. Gas is
also used to power vehicles and generate electricity. Many homes and industries use gas as their main source
of heating and cooking.
To use the energy stored in fossil fuels it must go through many stages of processing. First the fuel must
be extracted from rock deposits and transported to a processing station. The fossil fuels then need to be
converted into a form of energy that can be used. South Australia mainly uses natural gas to run its power
generators which then is delivered as electricity to our homes.
In South Australia around 98.5% of the energy use
comes from fossil fuels and approximately 1.5%
from renewable resources
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don’t waste
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Energy Conversions
When we use energy we often convert it or change it from one form to another. The energy in fossil fuels and
other sources of energy is not always in the form we need. The purpose of energy conversions is to change
energy sources into more usable forms.
wood, food, oil, coal
gas
Fuel sources such as
and
contain energy stored in chemical form. The energy is
packed into the chemical structure of the fuel and is released when we convert or change it. For example food
contains units of energy called calories. When we eat food our bodies convert the calories to release energy
in the form of motion and heat. It is actually the energy from our food that allows us to move and keeps our
bodies at a constant temperature. A similar process takes place when we burn other fuels. The chemical
energy stored in them is released when they are changed or broken down by a conversion device. We use
conversion devices such as car engines to change chemical energy into thermal and mechanical energy to
make the motor vehicle move.
Electricity is a common form of energy produced through turbines and generators. These conversion devices
use various sources of energy such as fossil fuels, hydropower, wind, uranium, sunlight, waves and the tide to
produce electricity. The electrical energy is then converted or changed into other forms of energy such as heat,
light or mechanical energy that is used at homes, in schools and at work.
No conversion device is 100% efficient. There is always a loss of energy through the conversion process. For
example when we turn on an incandescent light it provides us with 5% light and 95% heat. We don’t use lights
for keeping us warm so the heat is considered lost energy. The efficiency of conversion devices is important
in obtaining the most from an energy source, particularly when non-renewable sources such as fossil fuels are
being used.
energy &
fossil fuels
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