Energy and power part II

prefixes PrefixSymbolFactorNumberNameScale (distances) TeraT ,000,000,000,000trillionDistance to closest star GigaG10 9 1,000,000,000billiondistance from earth to Sun MegaM10 6 1,000,000millionearth-moon radius kilok10 3 1,000thousanddistance across campus height of a human centic hundredthA bee milim thousandthThickness of fingernail micromu millionthdiameter of blood cells nanon billionthwavelength of visible light picop trillionthHelium atom (31 pm) femtof quadrillionthSize 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) $ E) $ 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) $ E) $ Flourescent lights = about 4x more efficient! That’s why CU uses flourescent lights instead of incandescent bulbs!

Cost of electricity fuelmarket costcost per kWh (1000 Cal) cost if converted to electricity coal$40 per ton0.4¢1.2¢ natural gas$10 per million cubic feet 3¢9¢ gasoline$3 per gallon9¢27¢ electricity$0.10 per kWh10¢ car battery$50 to buy battery 21¢ computer battery $100 to buy battery $4.00 AAA battery$1.50 per battery $

Energy units energy unitdefinition 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 C 1 Calorie = 4182 joules ≈ 4 kJ joule1/4182 Calories ≈ Energy to lift 1 kg by 10 cm ≈ Energy to lift 1 lb by 9 in kilojoule1000 joules = ¼ Calorie megajoule1000 kilojoules = 10 6 joules costs about 5 cents from electric utility kWh (kilowatt-hour)861 Calories ≈ 1000 Calories = 3.6 megajoules costs 10 cents from electric utility BTUBritish Thermal Unit 1 BTU = 1055 joules ≈ 1 kJ = ¼ Calorie QuadA quadrillion BTUs = BTU = J Total 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 earth D)A nuclear power plant produces about a MW – about a GW

valueequivalentexample of that much power use 1 watt1 joule per secondflashlight 100 watts bright light bulb; heat from a sitting human 1 horsepower (1 hp)≈ 1 kilowatttypical horse (for extended time) human running fast up flight of stairs 1 kilowatt (1 kW)≈ 1 hpsmall house (not including heat); power in 1 square meter of sunlight 100 horsepower≈ 100 kWsmall automobile 1 megawatt (MW)1 million (10 6 ) wattselectric power for a small town 45 megawatts 747 airplane; small power plant 1 gigawatt = 1 GW1 billion (10 9 ) watts large coal, gas, or nuclear power plant 400 gigawatt = 0.4 terawatts average electric power use US 2 terawatts= 2 x10 12 wattsaverage electric power for World Power examples

Solar power 1 square meter 1 kilowatt of sunlight 150 – 400 watts electric using solar cells 1 square kilometer 1 Gigawatt of sunlight 150 – 400 Megawatts electric

Fossils Levels (amount in ground): Coal: 4.4 Tboe Oil: 1.2 Tboe Natural gas: 1.2 Tboe Flows (daily production): Coal: 52 Mboe/day Oil: 84 Mboe/day Natural gas: 19 Mboe/day Years of production left (using current #s  most optimistic): Coal: 231  417 years Oil: 39  43 years Natural gas: 173  167 years In 2008, the U.S. energy use was: 84% fossils 9% Nuclear 7% 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.”