Energy and power part II. prefixes PrefixSymbolFactorNumberNameScale (distances) TeraT10 12...
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Transcript of Energy and power part II. prefixes PrefixSymbolFactorNumberNameScale (distances) TeraT10 12...
Energy and powerpart II
prefixesPrefix Symbol Factor Number Name Scale (distances)
Tera T 1012 1,000,000,000,000 trillion Distance to closest star
Giga G 109 1,000,000,000 billion distance from earth to Sun
Mega M 106 1,000,000 million earth-moon radius
kilo k 103 1,000 thousand distance across campus
100 1 height of a human
centi c 10-2 0.01 hundredth A bee
mili m 10-3 0.001 thousandth Thickness of fingernail
micro mu 10-6 0.000 001 millionth diameter of blood cells
nano n 10-9 0.000 000 001 billionth wavelength of visible light
pico p 10-12 0.000 000 000 001 trillionth Helium atom (31 pm)
femto f 10-15 0.000 000 000 000 001 quadrillionth Size of proton
A MWh is a unit of:
A) Charge
B) Energy
C) Current
D) Power
E) Cost
I burn 2000 light bulbs for 10 hours. How much does this cost? ($0.10/kWh)
A) $0.20
B) $2.00
C) $20.00
D) $200.00
E) $2000.00
Cost of energy
Cost of energy
I burn 2000 light bulbs for 10 hours. How much does this cost? ($0.10/kWh)
A) $0.20
B) $2.00
C) $20.00
D) $200.00
E) $2000.00
Flourescent lights = about 4x more efficient!Flourescent lights = about 4x more efficient!That’s why CU uses flourescent lights instead That’s why CU uses flourescent lights instead
of incandescent bulbs!of incandescent bulbs!
Cost of electricity
fuel market cost cost per kWh (1000 Cal)
cost if converted to
electricity
coal $40 per ton 0.4¢ 1.2¢
natural gas $10 per million cubic feet
3¢ 9¢
gasoline $3 per gallon 9¢ 27¢
electricity $0.10 per kWh 10¢ 10¢
car battery $50 to buy battery
21¢ 21¢
computer battery
$100 to buy battery
$4.00 $4.00
AAA battery $1.50 per battery
$1000.00 $1000.00
Energy unitsenergy unit definition and equivalent
calorie (lowercase) heats 1 gram of water by 1 C
Calorie (capitalized), the food calorie, also called kilocalorie
heats 1 kg of water by 1 C1 Calorie = 4182 joules ≈ 4 kJ
joule 1/4182 Calories≈ Energy to lift 1 kg by 10 cm≈ Energy to lift 1 lb by 9 in
kilojoule 1000 joules = ¼ Calorie
megajoule 1000 kilojoules = 106 joulescosts about 5 cents from electric utility
kWh (kilowatt-hour) 861 Calories ≈ 1000 Calories = 3.6 megajoulescosts 10 cents from electric utility
BTU British Thermal Unit1 BTU = 1055 joules ≈ 1 kJ = ¼ Calorie
Quad A quadrillion BTUs = 1015 BTU = 1018 JTotal US energy use ≈ 100 quads per year;
total world use is ≈ 400 quads per year
Power
Is a MegaWatt a lot?
A) A horse can output about a MW
B) A Ferrari could output a MW at peak acceleration
C) That’s about the entire power output of the sun
D) A nuclear power plant produces about a MW
Power
Is a MegaWatt a lot?A) A horse can output about a MW – 1 kW
is about a hp (+34%)B) A Ferrari could output a MW at peak
acceleration – 750 kW max…C) That’s about the entire power output of
the sun – 173,000 TW hits the earthD) A nuclear power plant produces about a
MW – about a GW
value equivalent example of that much power use
1 watt 1 joule per second flashlight
100 watts bright light bulb;heat from a sitting human
1 horsepower (1 hp) ≈ 1 kilowatt typical horse (for extended time)human running fast up flight of stairs
1 kilowatt (1 kW) ≈ 1 hp small house (not including heat);power in 1 square meter of sunlight
100 horsepower ≈ 100 kW small automobile
1 megawatt (MW) 1 million (106) watts electric power for a small town
45 megawatts 747 airplane;small power plant
1 gigawatt = 1 GW 1 billion (109) watts
large coal, gas, or nuclear power plant
400 gigawatt= 0.4 terawatts
average electric power use US
2 terawatts = 2 x1012 watts average electric power for World
Power examples
Solar power
1 square meter
1 kilowatt of sunlight150 – 400 watts electric using solar cells
1 square kilometer
1 Gigawatt of sunlight150 – 400 Megawatts electric
Fossils
Levels (amount in ground):Coal: 4.4 TboeOil: 1.2 TboeNatural gas: 1.2 Tboe
Flows (daily production):Coal: 52 Mboe/dayOil: 84 Mboe/dayNatural gas: 19 Mboe/day
Years of production left (using current #s most optimistic):Coal: 231 417 yearsOil: 39 43 yearsNatural gas: 173 167 years
In 2008, the U.S. energy use was:84% fossils9% Nuclear7% Renewables
Extra clickers…
Didn’t get to these 31 Aug 2010
In Chapter 1, “smart rock” refers to:
A) a kind of low-calorie food
B) the asteroid that killed the dinosaurs
C) a method for shooting down missiles
D) uranium ore
A disadvantage of hydrogen fuel is that:a) it contains less energy per pound than gasoline.b) it cannot be made into a liquid, even at low
temperature.c) it is highly poisonous and corrosive.d) it can’t be mined, but must be “manufactured.”