Transcript Energy

ENERGY
Almost all energy
we use comes
originally from
the sun.
We use energy
sources to
generate
electricity.
There are two types of
energy -- stored
(potential) energy and
working (kinetic)
energy.
Radiation, conduction,
convection
Conduction,
convection and
radiation are the three
major methods of heat
transfer.
They are the three
different ways
that heat can
spread.
Conduction is the
transfer of heat
through an object.
When something is
heated the atoms
start to move faster.
As they move faster
they collide with
atoms next to them,
which collide with
atoms next to them.
This creates a chain
reaction that actually
moves the heat along a
path, outward from the
starting point where the
heat was added.
This is what's
happening if you've
ever set a pan on the
stove.
The handle gets warm
even though only the
bottom touches the
burner because the
metal conducts the
heat.
heat travels from candle
to metal rod
to hand
Convection is the
transfer of heat
energy by
movement of
currents.
It causes currents of
warm and cool air to
move and occurs in
liquids and gases.
You may have
heard of the
phrase “hot air
rises”.
This is
convection.
Heat leaves a
coffee cup as the
currents of steam
and air rise.
The heat moves
with the fluid.
Radiation has to
do with light.
One of the most
important types of
radiation we receive
on earth is from the
sun.
The sun sends
waves of heat
through space to
warm our planet.
Only about 51% of the sun’s rays
are absorbed by the earth
The light that you
see is actually
made up of
waves.
When something is hot,
like the burner on your
stove, it releases some
of its energy in the
form of waves.
The waves travel
through the air until
they hit something,
which gets heated
up.
This is why you can
feel the heat from
your stove even if
your hand isn't
actually touching it.
The burner
literally
'radiates' heat.
The different
forms of energy
are stored in
different ways.
Electrical
energy cannot
be stored
directly.
Electrical energy can be
indirectly stored by
converting the electrical
energy to some other
form of energy ("storage"
energy).
When a supply of
electrical energy is
required, the storage
energy is reconverted
back to electrical
energy.
Large quantities of
"storage" energy are
difficult to store and
reconvert.
Energy sources are divided into
two groups –renewable (energy
we can use over and over again)
and nonrenewable (energy that
we are using up and cannot
recreate in a short period of
time).
Renewable energy
sources include solar
wind, geothermal,
biomass, and
hydropower.
Another nonrenewable
energy source is the element
uranium, whose atoms we
split (through a process
called nuclear fission) to
create nuclear energy.
Nonrenewable
Energy
Much of our current
energy supply comes
from coal, oil, natural
gas, or radioactive
elements.
They are considered nonrenewable because once
they are removed from
the ground and used, they
are not immediately
replaced.
In fact, the world's
natural gas, crude
oil and coal deposits
took millions of
years to form
Petroleum Products
• Ink
• Crayons
• Bubble gum
• Dishwashing
liquids
• Deodorant
• Eyeglasses
• CDs and
DVDs
• Tires
• Ammonia
• Heart valves
RENEWABLE
ENERGY
Renewable energy
refers to sources of
energy that are
always there.
You might think that
we would be tapping
these energy resources,
but there is a catch.
While the energy is there,
the cost of getting it is
actually greater than using
our more popular energy
sources of fossil fuels and
uranium.
An important
advantage of
renewable energy is
that it produces much
less pollution.
Renewable
energy
Renewable
sources of energy
can be used over
and over again
Renewable resources
include solar energy,
wind, geothermal
energy, biomass and
hydropower.
Solar energy
comes from the
sun.
Some people use
solar panels on their
homes to convert
sunlight into
electricity.
Wind turbines, which
look like giant
windmills, generate
electricity.
Geothermal
energy comes
from the Earth's
crust.
Engineers extract steam
or very hot water from
the Earth's crust and use
the steam to generate
electricity.
Biomass includes
natural products
such as wood,
manure and corn.
These materials
are burned and
used for heat.
Dams and rivers
generate
hydropower.
When water flows
through a dam it
activates a turbine,
which runs an electric
generator.
GEOTHERMAL
Our earth's interior like the sun provides heat
energy from nature.
This heat - geothermal
energy - yields warmth
and power that we can
use without polluting
the environment.
Geothermal
energy is residual
heat of the earth.
The heat from the
earth's core
continuously flows
outward.
This natural energy
heats water trapped
under the ground and
releases it as steam or
hot water.
Today we drill wells
into the geothermal
reservoirs to bring this
hot water to the
surface.
heat of steam from
geothermal sources
areas geothermal sources
The hot water or
steam can be used
directly to cook and
warm homes or it can
be changed into
electricity.
Steam turns
turbine, which
turns generator
that produces
electricity
Nuclear
Energy
Well-constructed
nuclear power plants
have an important
advantage -- they are
extremely clean.
There are, however,
significant problems
with nuclear power
plants.
Mining and
purifying uranium
has not, historically,
been a very clean
process.
Improperly
functioning nuclear
power plants can
create big problems.
Chernobyl scattered
tons of radioactive
dust into the
atmosphere.
Spent fuel from nuclear
power plants is toxic for
centuries, and, as yet,
there is no safe,
permanent storage
facility for it
Transporting
nuclear fuel to and
from plants poses
some risk.
These problems have
largely stopped the
creation of new
nuclear power plants
in the United States.
BIOMASS
The term "biomass"
refers to any form of
plant or animal
tissue.
In the energy industry,
biomass refers to wood,
straw, biological waste
products such as manure,
and other natural materials
that contain stored energy.
The energy stored in
biomass can be released by
burning the material directly,
or by feeding it to microorganisms that use it to
make biogas, a form of
natural gas.
the energy from 2 tons of
garbage = 500 lbs of coal
Hydropower
Hydro means water.
So, hydropower is
"water power."
Top hydroelectric
plants
Hydroelectric power, a
renewable resource, is
generated when hydraulic
turbines are turned by the
force of moving water as it
flows through a turbine.
The water typically
flows from a higher
to a lower elevation.
These turbines are
connected to
electrical generators,
which produce the
power.
Wave energywater is sent through
channels which makes the waves
stronger. The water then turns a turbine.
Solar Thermal
Energy
The sun's heat can
be used in two
ways
The sun can heat water for
domestic hot water systems,
or the sun's light can be
concentrated and water
temperatures increased to
make steam and electricity.
These solar thermal
power plants rely upon
curved mirrored troughs
that concentrate
sunlight.
The sun heats a
liquid that creates
steam to turn a
traditional turbine.
solar panels
in space
WIND
ENERGY
Wind is created because
of different heating of
land and water areas by
the sun creating
movement of air from one
area to another.
Man has been using
the wind to do work
for thousands of
years.
The kinetic energy of
the wind can be changed
into other forms of
energy, either
mechanical energy or
electrical energy.
Wind energy has been
used for many years to
pump water from wells
and grind grains to
make flour.
Windmills can be
connected to a shaft
which in turn is
connected to a generator
to make electricity.
Tidal turbines are
similar to wind
machines except it
is the tide not the
wind which causes
the blades to turn.
They are used in
Europe but are not
economical in
the U.S.
Nuclear
Energy
Nuclear power plants
provide about 17
percent of the world's
electricity.
Nuclear power is
generated using
uranium, which is a
metal mined in various
parts of the world.
Nuclear power stations
work in pretty much the
same way as fossil fuelburning stations, except that
a "chain reaction" inside a
nuclear reactor makes the
heat instead.
The reactor uses
uranium rods as fuel,
and the heat is
generated by nuclear
fission.
Neutrons smash into the
nucleus of the uranium
atoms, which split roughly
in half and release energy
in the form of heat.
This heat turns
the water into
steam.
Then the steam drives
turbines which drive
generators and produces
electricity.
Modern nuclear power
stations use the same
type of turbines and
generators as
conventional power
stations.
If the rods become
uncovered by water,
deadly radiation is
released into the air and
contaminates the area
surrounding the plants for
miles.
Nuclear waste
can be stored
in caves or in
above ground
cement and
metal canisters.
The radiation will
remain deadly for
thousands of
years.
Mechanical energy
can be transformed
into electrical energy
or thermal energy.
Examples include
wind turbines
(electrical energy) and
refrigerators (thermal
energy).
Electrical energy can be
transformed into
mechanical energy
(using an elevator) or
thermal energy (by
using a space heater).