Transcript Lecture on Energy

Energy Consumption
Dr. Farid Farahmand
Cost of one KWatt-hour
How Much Energy Do we Use?
Total Energy Consumption of the World in 2010:
15 x 10^12 Watts! = 15 TWatt
Most of this comes form fossil fuel (coming from remain
of plants and animals):
• Oil
• Coal
• Gas
 CO2 Emission  Climate Change!
Energy Usage
U.S. household energy
http://michaelbluejay.com/electricity/howmuch.html
Power Consumption of Different Appliances
W-Hour Continuous Use
Alternative Sources of Energy
Where does energy come from?
Solar Power
Sun provides abundance of energy that can be used
for different applications:
• Solar Heating
• Solar Cooling
• Solar Cooking
• Solar Electricity
Converting Solar Energy to Electricity
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The output current of this reaction is DC (direct) and the
amount of energy produced is directly proportional to the
amount of sunlight put in.
Cells only have an average efficiency of 8-30%
Waldpolenz Solar Park (East Germany)
http://www.dw-world.de/dw/article/0,2144,3430319,00.html
How PV Systems Work
What DO You Build?
DEMO
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Solar Panels: Series or Parallel
Connecting PVs to the load
AC vs DC
IV-Curve of PVs
How to Read Your Electric Bill
http://131.89.128.67/myhome/myaccount/charges/
Calculating Your Footprint: How much greenhouse gas emissions
such as carbon dioxide (CO2) is generated to produce the required
amount o of energy.
http://131.89.128.67/myhome/environment/calculator/
Question
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I'm trying to determine how many amps I'm putting on a circuit so I don't
overload it, but I'm having a hard time understanding the labels. For
instance, my DSL modem adapter says "INPUT: 120V 60Hz 30W" and
"OUTPUT: 12VAC 1.67A" I understand how to convert watts to amps [Watts
/ Voltage = Amps], so it looks like in this case the input (30 watts or .25
amps) is less than output (200.4 watts or 1.67 amps). What am I missing?
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The output is 12V x 1.67A = 20W, which is less than the 30W input. Output is
always less than input, because the conversion process is inefficient.
Vampire power!
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Things that use electricity even when they're off
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How much standing power are you using?
power strip with individual switches
References
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http://michaelbluejay.com/electricity/how
much.html