Humans need
energy in order to perform various functions. These functions can be
anything from walking to the process of digestion. As humans, our source
of energy comes from food. Food is a form of chemical energy. However
there are many different forms of energy.
Other Energies
HEAT or THERMAL Energy Hot objects are sources of heat
energy. Examples are radiators or fires.
LIGHT Energy The sun, light bulbs and lamps are all luminous
objects. They give off light energy.
SOUND Energy Vibrating objects give off sound energy. Examples
include hi-fi systems and musical instruments.
ELECTRICAL Energy Electrical energy is available every time a
current flows.
CHEMICAL Energy Chemical Energy comes in a variety of forms.
Examples include food, petrol and batteries.
KINETIC Energy This is the energy that an object has because it is
moving. Examples include wind and flowing water.
ELASTIC POTENTIAL Energy Objects such as springs or rubber bands
that are stretched contain elastic potential energy.
GRAVITATIONAL POTENTIAL Energy Objects in a high position, that
have the ability to fall have gravitational potential energy. An example
is a waterfall.
NUCLEAR Energy Reactions that occur in the nucleus of an atom are
the source of Nuclear Energy.
STORED Energy Several of the other energies mentioned are forms of
stored energy. Stored Energy is where the energy is waiting to be used.
Energies such as chemical energy, elastic potential energy and
gravitational potential energy are all stored energies. Examples include
the food within the human body through chemical energy.
Energy Transfers
When energy is used it does NOT disappear. The energy is simply transferred into
other forms of energy.
For example, a light bulb transfers electrical energy into heat and light
energy.
A loudspeaker changes electrical energy into sound energy.
1.
Can you complete the following examples of energy transfers below?
b.
Chemical energy --> Battery
c.
Sound energy --> Microphone
d.
Kinetic energy --> Generator
e.
Chemical energy --> Log Fire
f.
Gravitational potential energy -->
Water falling over a waterfall
g.
Chemical energy (food) --> Humans
h.
Elastic potential energy -->
Clockwork Mouse
Energy Resources
Fossil Fuels
Coal, oil and gas are fossil fuels. They are concentrated sources of energy,
formed from plants and animals that died over 100 million years ago. When they
died, they were covered in mud and earth. Subsequently the huge pressures and
hot temperatures changed them into the fossil fuels that we use today. Since it
takes so many millions of years to create these fuels, we consider them to be
non-renewable fuels. This means that once they have been used up, they cannot be
replaced.
Apart from the fact that they are non-renewable, there are several other
problems associated with fossil fuels. When fossil fuels are burned they produce
carbon dioxide, which is released into the atmosphere. This causes an increase
in the temperature of the earth and leads to a rise in the atmosphere. This is
called The Greenhouse Effect.
In addition when fossil fuels are burned gases are released that lead to acid
rain. There are also environmental factors that are created by mining for fossil
fuels or by oil spillage when oil is transported in tankers around the world.
Since it is a well-documented fact that fossil fuels will not last forever, we
need to consider possible ways to overcome any future shortfalls. This line of
research covers two basic concepts;
Firstly to reduce the amount of fossil fuels we use now in order that they may
last as long as possible.
Secondly to discover and use other sources of energy, preferably renewable
sources.
We can reduce the amount of fossil fuel consumed through a number of means.
However the most important point regards educating the public to waste less
energy through leaving lights on or not properly insulating their homes. In
addition scientists are continually trying to develop better cars that use less
petrol and are more efficient.
Renewable sources of energy include wind power, tidal power, wave power, solar
power and others. All these sources of energy have some advantages and
disadvantages as detailed further below.
Power Stations
The majority of electrical energy that we use at home is generated at power
stations. There are different types of power station but most of them use coal
or gas as their source of energy.
Alternative Energy Resources
GEOTHERMAL
In this process, water is pumped several kilometres below the ground to hot
rocks. These hot rocks turn the water into steam, which then rises out of the
ground and is used to drive turbines and hence create electricity. This is a
renewable source of energy that has no associated environmental or pollution
problems. However this source of energy is limited due to the very few suitable
sites that are available and the high cost of set up.
TIDAL POWER At high tide, water is trapped behind a dam. At low tide the water is released
and flows through the dam back out to sea. The gravitational potential energy of
the water converts into kinetic energy as it flows through the dam, driving the
turbines within the dam and thus generating electricity. This is a renewable
source of energy that is considered reliable. (After all there are two tides a
day.) There are initially high costs involved in building the dam. However after
any initial expense, the running costs are actually quite low.
SOLAR ENERGY
Solar Power is the process by which the energy carried in the sun's rays is
converted into electricity using solar cells. An alternative method of solar
power involves the sun heating water that is carried within dark coloured
panels, which absorb the sun's heat more easily.
There are absolutely no pollution implications with solar power. Solar Power
does have a high initial cost but this is easily offset by the benefits
thereafter. Obviously solar power has restrictions in countries where long hours
of sunshine are limited.
BIOMASS
The chemical energy stored in 'things that grow' such as wood can be released by
burning it.
This energy source can be maintained on an ongoing basis by growing successions
of trees and using then when needed. You are probably thinking that burning wood
is not very environmentally friendly and that this may add to the Greenhouse
effect. However this is not strictly true since the carbon dioxide released on
burning was taken from the atmosphere when the trees were still alive and
growing.
This is a renewable source of energy as well as being low-tech so that
developing countries can use it easily. However large areas of land are needed
in order to grow sufficient numbers of trees.
WIND POWER
Quite simply, the kinetic energy of the wind is used to drive turbines within
wind farms. These particular turbines are very similar in shape to windmills
although they are a lot sleeker. This is a renewable source of energy and is
also considered quite low-tech and therefore can be used in developing
countries.
HYDROELECTRICITY
This process uses the kinetic energy of water flowing downhill to drive turbines
and generators. This is a renewable source of energy that can be stored until it
is needed. However there is a high initial cost associated with this form of
energy and the increased threat to the environment through flooding.
WAVE POWER
In this process, the rocking motion of the waves is used to generate
electricity. The energy in the water waves allows a simple wave machine to rock
back and forth. This motion is used to generate electricity. This is a renewable
source of energy but it has very high initial costs with a very poor energy
capture. i.e. It does not generate large amounts of electricity.
Energy Comprehension
1) Name three types of stored energy?
2) What kind of energy does water form as it falls down a waterfall?
3) Name three fossil fuels?
4) Why are fossil fuels called non-renewable sources of energy?
5) Suggest three ways in which we can make fossil fuels last longer.
6) Name three ways in which water can be used as an energy resource.
7) Name two energy resources that can be used in developing countries.
8) Give one example of an object that uses elastic potential energy.
9) Which fossil fuels when burned, cause acid rain?
10) Name two energy resources that may be limited by the ability to find a
suitable site.
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Answers
1: Chemical Energy, Elastic potential energy, Gravitational potential
energy.
2: Kinetic Energy
3: Oil, Gas and Coal.
4: Fossil fuels are called non-renewable sources of energy because
they cannot be
replaced once used.
5: Better insulation,
more efficient engines, better use of renewable sources of energy.
