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.”