AGigawa(‐LevelSolarPowerSatelliteUsingIntensifiedEfficient

ConversionArchitectureBrendanDessanA

ShaanShah

NarayananKomerath

ExperimentalAerodynamicsandConceptsGroup

SchoolofAerospaceEngineering

2

ConferencePapersfromOurTeam

•  B.DessanA,R.Zappulla,N.Picon,N.Komerath,“DesignofaMillimeterWaveguideSatelliteforSpacePowerGrid”

•  N.Komerath,B.DessanA,S.Shah,“AGigawa(‐LevelSolarPowerSatelliteUsingIntensifiedEfficientConversionArchitecture”

•  N.Komerath,B.DessanA,S.Shah,R.Zappulla,N.Picon,“MillimeterWaveSpacePowerGridArchitecture2011”

3

Outline

•  TheSpacePowerGridArchitecture•  GirasolConverterSatelliteConceptualDesign•  GasTurbineComparisonwithBroadbandPV•  GirasolSatelliteMassSummaryandDesignConclusions

•  MirasolReflectorSatellites•  GirasolEffectonArchitectureAnalysis•  Conclusions

4

SpacePowerGridArchitecture

PhaseI•  Constella;onofLEO/MEOWaveguideRelaySats•  EstablishSpaceasaDynamicPowerGrid

PhaseII•  1GWConverterSatellites–“Girasols”

•  GasTurbineConversionatLEO/MEO

PhaseIII•  HighAl;tudeUltra‐lightSolarReflectorSatellites–“Mirasols”

•  DirectunconvertedsunlighttoLEO/MEOforconversion

5

SpacePowerGridArchitectureDeviaAonsfromTradiAonalApproaches

•  UsePrimaryBraytonCycleTurbomachineConversionofhighlyconcentratedsunlight(InCA:IntensifiedConversion) SpecificPower,s

•  SeparatethecollecAonofsunlightinhighorbitfromconversioninloworbit AntennaDiameter

•  MillimeterWaveBeamingat220GHz AntennaDiameter

•  UseTetheredAerostats EfficiencyThroughAtmosphere

•  PowerExchangewithterrestrialrenewableenergy CosttoFirstPowerBarrier

6

GirasolConverterSatelliteConceptualDesign

ConceptualDesignofa1‐GWConverterSatelliteWhatitmustdo?

•  Receivelargequan;;esofdirectedsunlight,convert,andbeampowerasmillimeterwave

•  Maximizeefficiencyofconversion•  Minimizeheatthatmustberadiated

•  Maximizespecificpower(powerbeamed/unitmass) launchcosts

7

GasTurbinevs.BroadbandPVConversion

PotenAalforOrderofMagnitudeImprovementUsingGasTurbine

8

GasTurbinevs.BroadbandPVConversion

•  BroadbandPVscaleslinearly•  SpecificPowerofHighIntensityPVarrayslimitedbyheatradia;onproblem

Why? SunIntensity=HeatThatMustBeRadiated= ATCSMass

FundamentalBroadbandPVissue:Broadbandenergymustpenetrateasolidsurfacelayerbeforephotonscandriveelectronsthroughthesemiconductorarray

9

IηCAIntensifiedEfficientConversionArchitecture

1.  PrimaryBraytonCycleConversion

2.  Op;onalNarrowbandPVConversionA]empttoachieve50%efficiencyatground,thuseachgirasolcollects2GWdirectedsunlight

Given high Brayton Cycle efficiency and high specific mass of mechanical to electrical converter

not cost effective to use narrowband PV conversion

10

Girasols

11

ClosedHeliumBraytonCycle

Helium

•  HighandConstantSpecificHeat•  HighThermalConduc;vity

•  LowMassFlowRateRequiredClosedHeliumBraytonCycleOperaAngInSpace

•  Star;ngPoint:IntercooledHeliumBraytonCycleLiquidFluorideNuclearPowerPlantCycle(DOE‐ORNL)

•  Eight125MWSec;ons–Dimensionssimilartojetengines

•  Alloysexistthatcanmeet3650KOpera;ngTemperature

•  Advantagesoverterrestrialjetengines:1.  Predictabilityoforbit2.  Noatmosphere3.  Temperatureinspace

12

GirasolTurbomachinery

1)   300m Collector 2)   Intensified Feed 3)   Heater 4)   Compressor 5)   Turbine and Generator 6)   Radiator 7)   Phase Array Antenna

Components:

13

ThermodynamicCycleAnalysis

Efficiencies Based on Jet Engine Efficiencies

14

GirasolSatelliteMassBudgetandCycleAnalysis

Element Mass, kg Percent

Collector 3,534 0.92 Cooling Sys. 168,000 44.0

Brayton Cycle 20,000 3.91 AC Generator 50,000 9.79 Cryogenics 20,000 3.91

220 GHz Amp. 17,000 3.00 Antennae 20,000 3.53

Propulsion 170,300 30.0 Misc. 30,930 5.45

Structure 56,700 10.0 Total Girasol 567,000

Total Mirasol 53,000

Total Mass 620,000

3650K He Gas Turbine Cycle Analysis

15

Mirasols

HighAlAtude(GEOorNearGEO),UltralightReflectorSatellitesdirectsunlighttogirasols•  U;lizetechnologysimilartosolarsails

•  Op;callinkingbetweenmirasols/girasols•  Sunlightwavelengthsonorderofμm

veryli]lebeamdivergence,evenoverlargedistances

16

GirasolSatelliteDesignConclusions

1.  Bysepara;ngsolarspectrum,narrowbandPVconversioncanextractroughly14% oftotalsolarpowerasDC

2.  Narrowbandconversionofpre‐separatedspectrumminimizesac;vethermalcontrolrequirement

3.  ClosedBraytonCyclecanachieveover80% conversionofremainingsolarspectrumtoACelectricalpower

4.  GivenhighBraytonCycleefficiencyandhighspecificmassofmechanicaltoelectricalconverter,not costeffec;vetousenarrowbandPVconversion

5.  Superconduc;nggeneratorsneededtoachievehighpowerperunitmassneededformechanicaltoelectricpower

6.  IηCAArchitecturewithBraytonCycleconverterandsuperconduc;ngACgeneratoroffersspecificpower>1.6 kW/kg vs.<0.2kW/kgforPVarchitectures

7.  FutureImprovementsandrefinementscouldleadto>3.4 kW/kg 

–  A poten9ally revolu9onary impact 

8.  Ifroadblocksencounteredwithheatrejec;onsystems,couldusespectralsepara;onandnarrowbandconversionwithPVtoincrease specificpower

17

TechnicalandEconomicResultsAnalysis:Breakevenvs.SellingPrice

Baseline: SPG Architecture presented at March 2011 IEEE Aero Conf IηCA: Current architecture including Iηca Concept

For Given Price of Power, Significant Improvement in Viability

18

TechnicalandEconomicResultsAnalysis:GirasolEffectonNPVTrough

Amount of Investment Required Reduced Significantly from Baseline

19

Conclusions:GirasolEffectonArchitectureSummary

1.  GirasolBraytonCycleIηCAoffersfar beCer efficiency and specific power, andshortertechnologypath,thanpreviouslyconsidereddirectconversionop;ons

2.  GirasolBraytonCycleIηCAgreatlyimprovesSSPviablity

3.  IηCAcanachievebreakeven by Year 31,withNPVtrough<$3T,at$0.11/kWh

20

QuesAons?

21

Backup

22

Backup