Transcript 9.1 What is Energy? - The Education Resource Centre

Energy
Energy Sources and Energy
Conversions
Objectives
Describe an energy conversion.
Give examples of energy conversions
among the different forms of energy.
Explain how energy conversions make
energy useful.
Know the non-renewable and renewable
sources of energy.
Energy Conversion
A change from one form
of energy to another.
Energy Conversion on a Trampoline
#2
#4
#3
#1
–––As
–Just
At
Stretching
the
the
before
person
top of
hitting
the
leaves
thetrampoline
jump,
the
thetrampoline,
trampoline,
all of
is like
the
kinetic
the
stretching
all potential
ofenergy
the potential
a energy
rubber
has been
energy
band.
is converted
converted
Potential
has been
into
into
converted
potential
energy
kinetic
intoisenergy.
kinetic
energy.
stored.energy.
Chemical → Kinetic→ Heat
Light → Chemical → ? ? ?
More Energy Conversions
Alarm
Clock
electrical → light & sound
Battery
chemical → electrical
Light Bulb electrical → light & heat
Blender
electrical → kinetic & sound
Assessment
Any questions?
Complete 'Energy conversions' worksheet.
What energy conversion is taking place in
this video? ForTheBirds.flv
Video to demonstrate energy can not be
created or destroyedCanYouCreateEnergy!!!!.flv
Energy & Machines
Machines make work easier by changing the
size or direction of the force.
When you use a machine, you transfer your
energy to the machine, and the machine
transfers that energy to the object.
Energy Transfer in a Bicycle
Importance of Energy Conversions
A way of getting
the form of energy
that YOU need.
Converting energy
to a useable form
increasing energy
efficiency and
reduces energy
waste
Non-renewable sources of energy
•
•
Burning coal, natural gas, turf and petroleum releases energy stored in the fuel as heat.
The energy contained by the fuels is derived from the energy of the sun.
..\..\..\..\..\Videos\RealPlayer Downloads\Fossil-Fuelled Electricity - How it Works.flv
Pollution Problem
Global warming is/may be caused by the "Greenhouse effect." (accumulation
of carbon dioxide in our earth's atmosphere) A layer of gas forms that traps
heat inside the atmosphere, thereby acting as the glass ceiling of a greenhouse.
Because heat is trapped by the carbon dioxide, it is believed that the earth is
slowly warming.
National Geo carbon emissions.pdf
A potential (but relatively distant) danger of global warming is the melting of
the so-called "polar ice caps" at the north and south poles. This occurrence
would cause the ocean level to rise and perhaps flood many coastal cities.
Before humans were around on the earth, there was a relatively even recycling
of carbon dioxide and oxygen. Plants require carbon dioxide to live, and they
emit oxygen in return. Animals, on the other hand, need oxygen, but exhale
carbon dioxide. But as humans began to burn fossil fuels to create energy
(especially beginning just before the 20th century during the "Industrial
Revolution"), more and more carbon dioxide was emitted into the air until the
balance was slowly destroyed.
Assessment
Write down 2 advantages of fossil fuels as a
source of energy
Nuclear energy
..\..\..\..\..\Videos\RealPlayer
Downloads\Nuclear Power - How it
Works.flv
Having watched this video do you think
nuclear energy is a renewable or nonrenewable source of energy?
Renewable Sources of Energy
(1) Hydro-electricity
Hydroelectric systems make use of the
energy in running water to create electricity.
Changes in Energy (Hydro electric energy)
(clip).flv
Water has kinetic energy when it flows from
higher elevations to lower elevations. This
energy spins turbines.
(1) Hydro-electricity
Advantages
Inexhaustible fuel source
Minimal environmental impact
Viable source--relatively useful levels of energy production
Can be used throughout the world
Disadvantages
Smaller models depend on availability of fast flowing streams or rivers
Can impact the mobility of fish and other river life. NOTE: Building a
fish ladder can lessen this negative aspect of hydroelectric power.
Can alter the water quality, in turn impacting on the wildlife.
(2) Solar energy
Most of the energy known to man is derived in some way
from the sun. When we burn wood or other fuels, we are
releasing the stored energy of the sun. In fact, there would
be no life on earth without the sun, which provides energy
needed for the growth of plants, and indirectly, the
existence of all animal life.
There are two ways in which solar power can be converted
to energy using solar panels. The first involves using the
energy of the sun to directly heat air or a liquid. The
second involves converting solar energy directly to
electricity.
(2) Solar Power
Advantages
Inexhaustible fuel source
No pollution
Often an excellent supplement to other renewable sources
Versatile--is used for powering items as diverse as solar cars and satellites
Disadvantages
Very diffuse source means low energy production--large numbers of solar
panels (and thus large land areas) are required to produce useful amounts of
heat or electricity
One major concern is the cost of solar power. Solar panels are not cheap; and
because they are constructed from fragile materials; they must constantly be
maintained and often replaced.
(3) Biomass
Biomass is simply the conversion of stored
energy in plants into energy that we can use.
Biomass includes wood, crops & grasses,
wastes and aquatic plants.
Biofuels - National Geographic Magazine
(4) Geothermal
The word geothermal comes from the Greek words geo (earth) and therme
(heat). So, geothermal energy is heat from within the earth. We can use the
steam and hot water produced inside the earth to heat buildings or generate
electricity. Geothermal energy is a renewable energy source because the water
is replenished by rainfall and the heat is continuously produced inside the
earth.
ENERGY INSIDE THE EARTH
Geothermal energy is generated in the earth's core, about 4,000 miles below
the surface. Temperatures hotter than the sun's surface are continuously
produced inside the earth.
(5) Wind energy
Wind generators take advantage of the power of wind.
Long blades, or "rotors", catch the wind and spin. Like in
hydroelectric systems, the spinning movement is
transformed into electrical energy by a generator
(5) Wind energy
One of the main problems with wind power is the space
that is used up by the so-called "wind farms." In some
cases, the space taken up can seriously alter the
environment.
The good news is that although wind farms require a great
deal of square mileage, there is quite a bit of space between
the actual wind machines. This space can be used for
agricultural purposes.
Another problem with wind power is that relatively
speaking, it does not generate very much energy for the
price. Perhaps this setback is made up for in friendliness to
the environment.
(6) Tidal/Wave energy
Tides are caused by the gravitational pull of the
moon and sun, and the rotation of the earth. Waves
are caused by the wind blowing over the surface of
the ocean. The energy of this moving water can be
harnessed to generate electricity.
Although tidal and wave energy don't produce
pollution, they can cause other environmental
problems. Can you think of any?
To sum up……
..\..\..\..\..\Videos\RealPlayer
Downloads\Renewable Energy.flv
For the Birds clip: http://www.youtube.com/watch?v=1uXEN_eRwo
Fossil fueled electricity:
http://www.youtube.com/watch?v=vBbhfQ1kDfw
National Geographic - carbon emissions: attached above.
There are two articles in the national geographic
magazine (you can look up the website) from October
2007 entitled 'The Carbon Crisis' and 'Growing Fuel'. I
read some of the first article in class and it really got
them talking.
Nuclear Power:
http://www.youtube.com/watch?v=fjgdgAhOzXQ
Hydro electric:
http://www.youtube.com/watch?v=htT_8sFJx1w