Transcript Topic 8: Power Production Renewable Resources 8.4 (B)

Allen High School
IB Physics SL
Source: Chris Hamper Physics
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Solar
Hydroelectric
Wind
Wave
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This is the future of energy!
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Let’s take a closer look . . . .
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The Sun emits 3.90 x 10 26 J of energy PER
SECOND!
The energy spreads out and by the time it
reaches Earth (radius = 1.5 x 10 11m), the
Sun’s power is less intense.
Power per unit area
3.90 x 10 26 = 1380 W/m2 -- This is the Solar
4π (1.5 x 10 11)2
Constant
◦ The Sun’s energy is either absorbed or reflected.
◦ We use the Sun’s energy to either heat something
or to make electricity.
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The amount of energy that reaches surface of
the Earth depends on how much atmosphere
it has to travel through.
Intensity depends on Latitude. The Sun
shines through the least amount of
atmosphere (most intense) when it is directly
above (most atmosphere at sunset and
sunrise = least intense).
Intensity also depends on the season; at
different times of the year, since the tilt of
the Earth varies throughout the year.
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Solar Heating Panel
◦ These are found on roofs of houses/buildings.
◦ Solar radiation is absorbed by the panel’s black
metal plate, which then warms water by conduction.
The warm water is then circulated.
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Photovoltaic Cell (Solar Cell)
◦ Converts solar energy into electrical energy.
◦ Similar to a battery’s conversion of energy, except
instead of chemical energy, it’s solar energy.
◦ The potential difference & current produced by one
cell is small, therefore many cells are connected
together.
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In a previous presentation, you learned that
hydroelectric power originates with the Sun
warming oceans; evaporation; clouds
condensing; and then the rain falling has a
high PE.
Note that height (in PE = mgh) would be the
average height of the water.
This process can produce electricity.
Dams store energy in the form of water.
Electricity is produced via generator when the
water is released. (See picture on next slide)
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Windmills have been around for a while for a
variety of purposes. Nowadays, we use them
to generate electricity.
You learned previously that wind is caused by
the Sun. The flow of warm air creates areas
of different pressure, causing air to move =
wind. The rotation of the Earth causes this
wind to move in circular patterns.
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Coastal winds are caused due to different
rates of heating of the land/sea.
We learned previously that water has a high
specific heat and warms in day and releases
at night. This air movement is wind.
Katabatic winds are formed when a high
pressure is caused by cold air pressing down
at the top of a mountain, resulting in a
downhill airflow.
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Waves crashing ashore = energy transfer
There are surface waves (small) or rolling
waves (originate out in ocean).
The energy of a wave alternates between PE
as the water is lifted up and the KE as it falls.
This method is (as are the others) limited to
the supply of waves consistently.
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A column half full of water. As
water flows in, it compresses the
air above pushing it through a
turbine, which (if you haven’t
guessed by now) generates
electricity.
The turbine is specially
designed so that as the
water drops back down
the column, the turbine
also turns as it pulls air
into the chamber.
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Renewable resources are usually
nontraditional and more expensive in the
beginning, but their benefits can have longterm effects.
The challenge of the future =
Make non-traditional the new traditional!