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Make a list of three different ways to generate electricity.
Describe how these methods work.
Electricity = electric current that is used as a power source!
Power Plant  Power Grid Homes  Outlets.
Current = the movement of charges such as electrons
(What powers household appliances.)
Charge Passing
Through A Given Area
Electric Current = -----------------------------Time
An easier way to think of electric current is to picture cars going
through a Toll Station.
Cars = electrons or charge
Toll Booth = the cross
sectional area of the
wire at a certain point.
Current = number of cars that passed through the toll booth (electrons)
the time it took for those cars to pass
Electric current generation - whether
from fossil fuels, nuclear, renewable
fuels, or other sources is usually
based on the:
In September of 1831, Michael Faraday
made the discovery of Electromagnetic Induction.
Faraday attached two wires to a disc and
rotated the disc between the opposing
poles of a horseshoe magnet creating
an electric current.
magnet + conductor (copper wire) ≠ electric current generated.
YOU NEED MOTION!
An electric current is not generated unless the magnetic field is moving
relative to the copper wire, or the copper wire is moving relative to the
magnetic field.
Electric Generators = magnets + copper wire + motion
Where does the
Motion come from
that keeps the
copper wire and
magnets moving
relative to one
another?
TURBINES!
Spin an armature that turns the copper wire
relative to the magnetic field. As long as the blades spin, electricity
will be generated!
Create a turbine and generator that will light a small light bulb
You will need to
1.Choose how to turn the turbine
2.Choose materials that will tolerate the stresses that will be generated
3.Design and build a turbine and generator that will work.
- AC of 60 Hz produced by generator
- Resistance losses are smallest at high voltages and low currents
At home, electric current
that was generated by
generators in the power
plant is used to power
electric appliances.
The electric current,
running through the
copper wire causes
the armature to spin
which is how most
motors generate
motion.
Where does the motion needed to keep the copper wire moving relative
to the magnetic field come from?
-attains between 50 – 70% efficiency
- one windmill’s average energy
output ranges from 11.4 W/m^2 –
57 W/m^2 depending on how windy
-wind farms tend to generate between
50 and 600 Kw
- California currently produces ¾
of all the wind generated electricity
in the world.
Wind generated
Kilronan Wind Farm In Ireland
-North Dakota with 20 times the wind potential of California has not
erected a single wind turbine
Wind power classes 3 (300-400 W/m2) to 7 (800-2000 W/m2) are suitable
for wind power development
-Wind variability must be overcome by system design
- Basic energy Storage
- Differences in pressure gradients around wind turbines affect birds
-Noise from the turbines affects people and animals
-Eyesore, the appearance of mile after mile of wind machines with
transmission lines is of concern to the public
-Conversion from potential energy of
water to electric energy is at 80 – 90%
efficiency
-Hydroelectric projects in the United
States have rated capacities from
950 – 6480 MW
-The use of Water Power is much
greater in some other countries.
Norway obtains 99% of its electricity
from water power. Nepal, Brazil, and
New Zealand are close seconds.
Water generated - Hydroelectric
Shasta Dam In California
- Hydroelectricity has dropped from producing 30 % to 10% of US electricity
- Large fluctuations in output are mainly due to variable rainfall totals
-About 50% of the United States potential for hydroelectric energy has been
tapped. However, further advances are unlikely.
-The Wild and Scenic River Act and the Endangered Species Act have
inhibited development of some sites
-Silt collection in hydroelectric Dam storage volumes over time causes
maintenance issues, as well as environmental concerns
-The loss of free flowing streams and land due to flooding behind the dam
disturbs the life of species: eg – Salmon
- Possibility of dam failure
Fossil Fuels – Oil Refinery
Pasadena - Texas
Standard Large Power Plants Provide 1 Giga-watt of electric power
and releases 2 Giga-watts of thermal power as waste heat. An
efficiency averaging around 30%.
-9000 tons of coal a day
-40,000 barrels a day or one tanker a week of oil
-generates about 5.3 x 10^9 kwh/year
-powers a city of a million people
-total world production in 1996 of
petroleum is 62,239x 10^3 barrels / day
-an average well in the US produces
only 11 barrels / day
-In Saudi Arabia an average well
produces 9600 barrels /day
Oil Drilling Platform
Cook Inlet, Alaska
-There are 109 power reactors in the United States
-Produce 22% of nation’s electricity
- In France 79% of electricity comes from nuclear reactors
Nuclear Power
-Plant electrical output 1220 MW
-Plant efficiency 34%
Diablo Canyon - California
-In normal operations a nuclear reactor produces some environmental
emissions. E.g.: escape of radioactive fission products through cracks and
diffusion, radioactive H3 in small amounts in discharged water
-Core meltdown are possible, but unlikely due to negative feedback and
shutdown systems
-Even after shutdown there is 7% of normal power generation still in the
reactor fuel rods. This may be sufficient enough to melt core and destroy
the reactor, if cooling water is not supplied
-A study entitled “Severe Accident Risks: An Assessment for Five US
Nuclear Power Plants” conducted by NRC in 1990, shows that for all the
109 reactors now operating in the United States over a 30 year lifetime
there is about a 1% chance of a large release due to internal events.
-Solar Power – uses the sun energy to either boil water or directly converts
solar energy to electrical energy
-Ocean Thermal Energy Conversion – uses temperature differences
between different depths of ocean water to drive a heat engine. Working
fluid is ammonia which is gas at room temperature.
-Biomass Energy: Municipal Solid Waste – burning wastes to drive heat
engines
-Geothermal Energy – based on naturally occurring heat in the Earth in the
Earth due to radioactive decay
-Tidal Energy – uses the gravitational pull of the moon on our oceans to
drive turbines
Proportion of World’s energy
consumption - 1997
Proportion of the world’s
Electricity generation - 1997