In your notes…
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What are the four ways we harness solar energy?
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What are the limitations of solar energy (at least 2)?
•
What approach should we take with alternative
energies in solving the energy crisis we have looming?
Fission
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The splitting of atomic nuclei in a chain reaction to release
energy (fission)
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Animation
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chain reaction
Animation
Fission
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Produces about 20% of the electricity in this country
Nuclear = Not Renewable
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The radioactive form of Uranium, U235
(isotope) is required and not commonly found
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Uranium must be mined.
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Mining is dangerous because of the slow
release of radioactivity
Radioactivity
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The nucleus of atoms are in
an unstable state releasing
protons and neutrons
causing the element to
change (decay) into another
form, eventually lead.
•
Radioactivity is found in
nature but it is harmful to
living cells in high dosages
(fission releases a
tremendous amount of
radioactivity)
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Navajo movie
Produces electricity
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Just like fossil fuel power plants, but contains a nuclear
reactor to produce heat.
How Nuclear power works
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Video
Energy in
U235
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Typical Heat Values of Fuels
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Firewood: 16 MJ/kg
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Black coal:24-30 MJ/kg
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Crude Oil: 45-46 MJ/kg
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Uranium: 500,000 MJ/k
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(MJ = Megajoules), *natural U
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2 pounds of U235 has the same energy as 16 tons of coal
Impacts
•
No air pollution
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There is radioactive waste
from mines, processing,
and disposal of uranium
Nuclear Fast Facts
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Since the mid-1940s, spent nuclear fuel
and high-level radioactive waste have
accumulated throughout the country.
Currently, they are stored in temporary
facilities at some 121 sites in 39 states.
These storage sites are located in a
mixture of urban, suburban, and rural
environments — most are located near
large bodies of water.
•
In the United States today, over 161
million people reside within 75 miles of
temporarily stored nuclear waste.
•
As of 1996 there was a cumulative total
of 32,000 metric tons of irradiated fuel
from commercial nuclear power
generation in the United States, nearly
all of it at the reactor sites.
Yucca Mountain
Impacts...
•
Many people fear power
plants due to possible
meltdowns (when
nuclear fuel becomes too
hot and escapes the
reactor chamber releasing
radioactivity into the
surrounding.
•
A partial meltdown
occurred at Three Mile
Island (PA) in 1979
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Worst meltdown
occurred at Chernobyl
(Ukraine )
Impacts Con’t
•
Worst meltdown occurred at
Chernobyl (Ukraine ) pg 451
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Aging plants must be maintained
which is very expensive. 81
reactors have been taken out of
service worldwide.
•
Dealing with nuclear material in
any way is very costly
•
New technology may change
plant design making them much
safer. Nuclear power will most
likely decline until changes occur
Nuclear Fusion
•
Fusion occurs when hydrogen
isotopes are combined to release
energy forming helium gas as a
by-product
•
One gram of deuterium fusion fuel
= 45 barrels of oil.
•
Extremely high temperatures are
needed to strip the hydrogen
atoms of the electrons making a
plasma.
•
This process occurs in the Sun
* This process has only occurred
experimentally