Energy&Sustainability

Lecture7:ElectricPowerGeneration

February3,2009

EfficiencyvsEfficacy•  Efficiency:

•  Abilityofconvertingelectricalpowertoradiantpower

•  isusuallygiveninpercent,ex.atypicalCFLis17%‐21%efficient

•  A15WCFLconvertsupto

0.83*15W=12.4Woftheelectricalpowerintoheat

€

η =Eout

Ein

Efficacy

•  Istheratioofluminousflux(inlumens)topower(usuallymeasuredinWatts)

•  Mostcommonlyused:ratioofluminousfluxemittedfromalightsourcetotheelectricalpowerconsumedbythesource

•  =>describeshowwellthesourcedoesatprovidingvisiblelightfromagivenamountofelectricity

ResponseoftheHumanEyeStandard luminosity function y(λ) under bright conditions (Photocopic Vision)

Function under dim conditions not shown here (Scotopic Vision: maximum at 507 nm, efficacy of 1700 lm/W)

683 lm/W @ 555 nm

LuminousEfficiency/Efficacy

IlluminationExample

•  Inputstage•  PowerStation•  Distributionsystem

•  Yourmeter

•  Usefulenergy!

IlluminationExample(2)

•  Ireadforonehourusinga60Wincandescentlamp:– HowmuchelectricalenergydidIuse?– Howmuchenergywaswastedasheat?– HowmuchvisiblelightdidIget?

– Howmuchprimary(coal)energydidIuse?

•  Ireadforonehourwitha15WCLF,whataretheabovenumbersinthiscase?

SummaryofPreviousLecture

•  IncreaseinWorldpopulation•  Dramaticincreaseinenergyuse

•  Unevendistributionsofenergyresources•  Self‐sufficiency,energyimporterandexporter

•  Availabilityofresourcesshapeenergysceneofacountry

•  Infrastructureimportantforbeingabletodevelopanduseenergyresources

SummaryofPreviousLecture(2)

•  ComparedUK,Denmark,USA,France,India•  RegionswhichneedmosthelpappeartobedevelopingcountriesofSouth&EastAsiaandAfrica

SummaryofPreviousLecture(3)

•  Possiblecuresofenergyproblem:– Significantimprovementsinenergyefficiency(technology)

– Tapintobroadportfolioofenergyresources,developtechnologiestosupplementandultimatelyreplacenonrenewablefossilfuels

– StabilizationofWorldpopulation

ElectricPowerGeneration

•  Energyusestoday•  ElectricPower

– Generation– Distribution(transmission)– Storage

•  Sustainableattributesandissues

Historictrends

•  1900:allcoal,veryinefficient– Coalfire– Gaslighting

•  2000:variedrange,moreefficient– Electricfire– Fluorescencelamps

– Butstillbiglossesatpowerstations

Currenttrends

•  Riseinconsumptioninservices=>increasedstandards,e.g.heating

•  Lighting•  Increaseinconsumptionattheworkplace:officesetc.

•  Airconditioning•  Largeriseintransportenergyuse:

– Travelbycar–  Internationalairtravel

InternationalComparison•  Source:InternationalEnergyAgency,2006

InternationalComparison(2)

•  HigherGDP,higherconsumption•  Butlargevariationamongthewealthycountries

•  Comparingenergyefficiencies:– Primaryenergyfromlesswastefulforms– EarntheirGDPfromlessintensiveactivities

– Useenergymoreefficiently– Usemorefornon‐productiveactivities

•  Historictrends

MajorGrowthArea

MajorGrowthArea

•  Transportation;andwehaveseenthattherewasanimportgapbetweenoilconsumptionandproductions

•  Anothermajorgrowthare:electricityuse

•  Energyuseallowsusto:– Uselesshumanlabor

– Carryactivitiesatnight– Manufactureanddistributeproducts– Newactivities:travel,communicationsetc.

PowerGeneration

•  Wind,tidal,riverflows,etc.

Historical Intro

PowerGeneration

•  Wind,tidal,riverflows,etc.•  Steamengine

Historical Intro

PowerGeneration

•  Wind,tidal,riverflows,etc.•  Steamengine

•  Oil&coal

Historical Intro

PowerGeneration

•  Wind,tidal,riverflows,etc.•  Steamengine

•  Oil&coal•  Electricitygeneration&motor

Historical Intro

PowerGeneration

•  Wind,tidal,riverflows,etc.•  Steamengine

•  Oil&coal•  Electricitygeneration&motor

•  Electricpower

Historical Intro

WhereDoWeGetElectricity?

•  Nuclear&Fossil•  Gas

WhereDoWeGetElectricity?

•  Non‐Thermal

WhereDoWeGetElectricity?

•  Solarinsolation

WhereDoWeGetElectricity?

•  Thermochemical

Nextlecture

•  Thepowergrid•  BalanceenergysupplyandStorage