Energy&Sustainability

Lecture17:FossilFuels–Cars

AndReview

March10,2009

Newton’s Laws:

1) body in motion stays in motion 2) F = m a

-You are driving at constant 60 mph Q: what is a? A: 0

- then why does engine need to run? A: FRICTION Microscopically: weak bonds are made and broken

- converts KE into thermal energy

Energy usage in transportation

EnergyUsageinTransportation

•  Q:whatarekindsoffriction?•  A:Rolling,Sliding,Static•  Inacar:engine;tires;drag

•  Slidingorrollingfriction:F=µmg:coeff.offrictionxweight

–  Ifma=F=µmgthenthemaxa=µg

•  Aerodynamicdrag:F=ρCdAv2:ρisfluiddensity;Cdiscoeff.ofdrag;Aisarea;

Cd=1.17forflatplate,0.3forgoodaerocar,0.9ofbicyclist

MilesPerGallon

•  Power=Fv=A+Bv+Cv3A:enginelosses,idling,accessoriesB:rollingfriction

C:drag•  Energy=Powerxtime

•  Time=distance/v

•  Energy=d(A/v+B+Cv2)•  MPG~d/E=1/(A/v+B+Cv2)

•  Goesas~v/Aforsmallv,1/(Cv2)forlargev:

•  Typicalmaxaround40–60mphdependingonA,C

VWGolfGTI

~v/A for small v 1/Cv2 for high v

Trainsaremuchmoreefficientthancars‐Why?

1)  rolling friction << less (metal on metal) 2) A per volume much less ( cars draft each

other)

BacktoAutos•  Fourplacesenergyisexpended

1)idling/AC/radioetc.

2)accelerating3)overcomingfriction(rolling,drag)

4)climbinghills

A1300kgcaronasphaltw/regtireswillneedaforceof400Nforrolling.

Thislimitsacarofthiswgttoabout60MPGevenatslowspeedsIfyouuselowresistancetiresyoucanpushthisafactorof2(The

Priushaslowresistancetires)–Thisiswhyitisimportanttokeepyoutiresinflatedproperly

EnergycontentandCO2emission

Review

•  Theexamisacombinationofafewsimplecalculationsandshortanswerquestions

•  Exampleforshortanswerquestion:– Whyishydroelectricityusedinpeakpowerproduction?

– Becauseitcandeliverelectricalpowerondemandandquicklythroughforexampleapumpedstoragepowerplant.

Formulasonthelastpageoftheexam

Rule#1

•  1stLawofThermodynamics:

Energy can never be created or destroyed

Energy is conserved

Or in other words

Rule#2

•  2ndLawofThermodynamics

A “disordered” Universe is far more probable than an “ordered” one

There is an irreversible tendency toward a disordered Universe full of useless, low-grade energy

ProbabilityandEntropy

•  The2ndLawforisolated,randomsystemswithalargenumberofelements(likeourUniverse):– “Disorderismuchmoreprobablethanorder”

– “thedirectionofspontaneouschangeasaresultofrandominfluenceisfromorder(lowprobability)todisorder(highprobability)”

•  Entropyistheaquantitativemeasureoftheextentofdisorderinasystem

WhatisEnergy?•  PhysicsDefinition‐Thecapacitytodowork•  Severaldifferentformsofenergy:

– kinetic,potential,thermal,electromagnetic,chemical,nuclear,andmass

•  Energyisconserved– Energycannotbecreatedordestroyed‐onlytransformedfromoneformtoanotherortransferredfromonesystemtoanother

•  Workisaforcetimesadistance‐– Exampleraiseanobjectup‐giveitpotentialenergy– Applyaforcetoacar(bythewheelsontheroad)overadistanceanditgains(orloses)Kineticenergy

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EnergyUnits•  Joule=1kgm2/s2‐Metricunitofenergy

•  calorie=energytoraisetemperatureof1gofwaterbyonedegreeC

•  1calorie=4.186J

•  Calorie(food)=1kcal=1,000calories

•  1kcal(Calorie)istheequivalentenergytokeepa100wlightbulbonforabout7minutes

•  BTU(BritishThermalUnit)=energytoraisetemperatureof1lbofwaterbyonedegreeF=1,055J=0.25Kcal

Whatisworkagainstgravity?

h w=mg

•  Workdonetoliftblock=mghThisresultsinpotentialenergy

FormsofEnergy

•  Work=f*dinthedirectionofforce•  Kineticenergy=1/2mv2

•  GravitationalPotentialEnergy=mgh,wherehcanbee.g.inthecaseofpumpedstoragetheeffectivehead;g=9.81m/s2istheaccelerationduetogravitation;misthemass

•  Fallingbodyhasspeedv=(2gh)1/2

WhatisPower?  Definition- Rateofenergyexchangebetweentwosystems:energy/time

 Mayrepresentaflowofwork,heat,orboth

  Units:1W=1J/1s

Power•  Rateofdoingwork•  Icanrunupa3mflightofstairsin~5s

•  Mgh=65kg*10m/s2*3m=1950J

•  Power=1950J/5s=390Watts

•  Averagepower‐2400kcals/day‐~100kcals/hr=418kJ/h=418,000J/3600s=118W

•  BasalMetabolic(resting)Rate~0.6kcal/h/kgsoforme

•  BMR=65*0.6=39kcals/h~46WSothatishowmuchheatIproducewhiledoingnothing

Units•  Largenumbers:

103

106

109

1012

1015

1018

Unitsofpowerandenergy  1TW=1millionmillionW=1012W

  Example:we,theworldpopulation,withourconsumptionrateof~16TW,convert16trillionjoulesofprimaryenergyeverysecondintoformsofenergywewant(+wasteheat)

  1kWhistheamountofenergyconvertedinonehouratarateofonekilowatt  1kWh=3.6MJ

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U.S.EnergyConsumptionby Source

U.S.EnergyUse

•  In1991,theU.S.consumed81.5quads

•  Estimatedusefor2000was96.2–100quads•  Howmuchisaquad?

–  1quad=1015(1,000,000,000,000,000)BTUs–  1BTU=energyrequiredtowarm1lbwater1oF

–  1quad=1.05x1018J‐>100quads=~1020J

AveragePowerPerPersonintheUS

•  100quads‐howmuchaveragepoweristhat?

–  ~πx107seconds/year=3.15x107seconds/year–  1020J/year/3.15x107seconds/year=3x1012W

–  3trillionwattsistheaveragepowerconsumedintheUS–  300Millionpeople

–  3x1012w/3x108people=104w/person=10kW/person•  24hrsperday(includesindustry,travel,heating/AC‐everything

•  10kW*86,400sec/day=864,000J/d=206,000kcal/d•  Orabout100timesourbasic/primitiveenergyneeds

Population•  Currentlythereare6billionpeopleonearth(6x109)•  Therateatwhichpopulationgrowsisproportionaltothe

existingnumberofpeople–  Thenumberofpeopleborndependsonthenumberofpotentialparents

– Atthecurrentrateofgrowththepopulationdoublesevery35years(aspeoplelivelongerthisgetsshorter)•  Ifyou(andapartner)have2childrenby35andtheydothesamewhenyouare70therewillbesixofyou.

–  Thenassumingyoudieoff(whichhavingkidscancause)thepopulationhasgonefrom2whenyouwhere<35to4whenyouaregoneat70…

•  Thisisexponentialgrowth

Thelilypad

•  Alilypaddoublesinsizeeveryday•  Itstartsat1/1,000,000thesizeofthepond•  Howlongdoesittaketofillthepond?

– 2n=1,000,000– 210=1024=~1000– 1,000x1,000=1,000,000=106– 210x210=220=~1,000,000– So~20days

ExponetialGrowth• 

• 

•  • 

• 

ElectricityBasics•  Carriersofelectricity:electrons•  Current:

–  Symbol:I=Q/t–  numberofelectronspersecond

–  Unit:amporA,1A=1C/s,e≈1.602x10‐19C

1Aisdefinedasthecurrentrequiredtoproduceamagneticforceof2x10‐7N/mbetweentwoinfinitelylong

thinwiresspaced1mapartinthevacuum

•  Voltage:-  Symbol:V=W/Q

-  differenceinelectricalpotentialthatasupplymaintainsbetweenitsterminals,ameasureoftheenergysuppliedtoelectricchargesastheypassthrough

-  Unit:1V=1J/1C,energysuppliedis1J

ElectricityBasics(2)

•  Resistance:–  SymbolR=V/I

–  Ohm’slaw:resistanceofacomponentisthevoltageacrossitdividedbythecurrentflowingthroughit

–  Resistanceiscomponentdependent

–  Maynotbeinpracticeaconstant(e.g.increasingcurrentinawiremaycauseincreasingcomponenttemperatureandusuallycausesincreasingresistance

–  V=RxI–  Unit:1Ω(ohm)=1V/1A

ElectricityBasics(3)

•  ElectricPower:–  rateatwhichenergyistransformed

–  Proportionaltotheproductofthevoltageandthecurrent:P=VxI=RxI2=V2/R

-  Relationshipholdsequallyfortheelectricalpowerprovidedbyasupplyorthepowerbeingdissipatedasheatinacomponent

-  Unit:1W=1Vx1A

•  Unitofstoredcharge,e.g.inacarbattery:Ampere‐hour:1ampere‐houristheelectricchargetransferredbyasteadycurrentofoneampereforonehour

LossesinPowerTransmission

•  V=IR•  PowertransmittedisP=VI

•  PowerdissipatedbyP=I2R•  Ploss=I2R=P2/V2R

•  Soforfixedpowertransmittedthehigherthevoltagethelowerthecurrentandthelesstheloss

•  ModernTransmissionrunsat380KVto735KV

Transformer

•  Transformsvoltagesinanelectricalsystem•  Stepuporstepdown•  Workonalternatingcurrents(mutualinteractionof

changingelectrical

andmagneticfields)

•  Idealtransformer:

•  Vp/Vs=Is/Ip(Pp=Ps)

•  Vp/Vs=Np/Ns

ElectricityFlow

65 % losses

U.S.vsUtah

Compared to Utah:

Coal: 82%

Hydroelectric Power: 1.2%

CapacityFactorThe amount of energy that a power plant actually generates compared to its maximum rated output, expressed as a percentage.!

BalancingSupplyandDemand:‘MeritOrder’

•  Baseload:lowestrunningcosts,usuallynuclearorlargecoalfiredstations(>600MW),thermalefficiencyof~40%,buttakes8hourstorampup

•  Middlemeritorderorintermediate:smallercoal‐firedstationswithlowerthermalefficiencies

•  Peakingplants:simplegasturbines,thermalefficiencyunder30%,possiblefuels(naturalgasorkerosene)arelikelytobemoreexpensive,butcanberampedupinthematterofminutes

CanadianLoadDurations•  UShaslesshydroasafractionandmorenuclearinourbaseload

<- Correlated demand

HydroelectricityandPumpedStorage

BenefitsofHydro‐electricity•  NoCO2

•  Noparticulatesorchemicalcompoundssuchasdioxinsthatareharmfultohumanhealth

•  Noemissionofradioactivity•  Nomajorexplosionsorfire•  Oftenassociatedwithpositiveenvironmentaleffectssuchasfloodcontrolorirrigation

•  Valuedamenityorevenavisualimprovementoflandscape

DeleteriousEffects

•  Hydrologicaleffects–waterflows,groundwater,watersupply,irrigationetc.

•  InthecaseoftheGabcikovo‐NagymarosProject–  fallinthewatertable–  Wellsdryingup

–  Vegetationdying–  Uniqueformsofwild‐lifeindanger

•  Socialeffects•  CanproduceMethan

Projections

•  Hubbertetal.

KeyAssumptions:EIA’sInternationalEnergyForecast

•  Potentialimpactsofproposedlegislationorstandardsarenotreflectedintheprojections

•  Potentialimpactsoflegislationforwhichimplementingmechanismsarenotsetalsoarenotreflectedintheprojections

•  Projectionscomefromanintegratedsetof16regionalmodelsthatreflecteachregion’sexistingenergyusepatterns,energyinfrastructure,andcostsforexistingandalternativeenergytechnologies

•  Forfurtherdetailssee:http://www.eia.doe.gov/oiaf/ieo/pdf/0484(2007).pdf

8

AnnualGrowthinElectricityGenerationbyRegion(2004‐2030)

Non-OECD

OECD – Organization for Economic Co-operation and Development

Source: EIA, International Energy Outlook 2007

9

Non-OECD

OECD

AnnualGrowthinLiquidsConsumptionbyRegion(2004‐2030)

Source: EIA, International Energy Outlook 2007

10

0.0

1.9

2.3

2.2

FutureChallengesandOptions

  85%ofthatincreaseisintheU.S.,China,India,&otherAsia

  U.S.,ChinaandIndiaaccountfor86%oftheincreaseinglobalcoaluse

  GlobalCO2emissionsincreaseby60%

  90%oftheincreaseinCO2emissionsoccursintheU.S.,China,India,&otherAsia

  Coalaccountsfor49%ofglobalCO2emissiongrowth

  Oilaccountsfor29%  NaturalGasaccountsfor21%

Source: EIA, International Energy Outlook 2007

WorldPrimaryEnergyConsumptionoverNext25YearsWithoutCarbonConstrainingTechnology

17

World primary energy consumption Increases 57%

Thearticles/talks

•  Article:4pagesexcludingfigures,doublespacing,withreferences

•  Talks:10to15minutes,about10slotsavailable

•  ExtraCredit:Youmayhandinanarticleinadditiontoyourtalk

Thearticles/talks

•  Introduction:Whatisthequestion/problemdiscussed?Whatisthecontext?

•  Scientificbackground•  Economicalbackground

•  Politicalbackground•  Prosandcons•  Conclusion•  Baseyourargumentationonsolidnumbersforwhichyoucangivereferences

Presentations

•  Gradingwillbeonpresentation.–  Isyourpresentationclear?–  Isitpersuasive?– Didyouusedatatosupportyoursuggestions?– Didyoucoverthekeypoints

Deadline

•  Pleasesendmeyourcompletearticlesandcompletepresentationsby

THURSDAY,MARCH272009