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AGigawa(‐LevelSolarPowerSatelliteUsingIntensifiedEfficient
ConversionArchitectureBrendanDessanA
ShaanShah
NarayananKomerath
ExperimentalAerodynamicsandConceptsGroup
SchoolofAerospaceEngineering
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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”
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Outline
• TheSpacePowerGridArchitecture• GirasolConverterSatelliteConceptualDesign• GasTurbineComparisonwithBroadbandPV• GirasolSatelliteMassSummaryandDesignConclusions
• MirasolReflectorSatellites• GirasolEffectonArchitectureAnalysis• Conclusions
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SpacePowerGridArchitecture
PhaseI• Constella;onofLEO/MEOWaveguideRelaySats• EstablishSpaceasaDynamicPowerGrid
PhaseII• 1GWConverterSatellites–“Girasols”
• GasTurbineConversionatLEO/MEO
PhaseIII• HighAl;tudeUltra‐lightSolarReflectorSatellites–“Mirasols”
• DirectunconvertedsunlighttoLEO/MEOforconversion
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SpacePowerGridArchitectureDeviaAonsfromTradiAonalApproaches
• UsePrimaryBraytonCycleTurbomachineConversionofhighlyconcentratedsunlight(InCA:IntensifiedConversion) SpecificPower,s
• SeparatethecollecAonofsunlightinhighorbitfromconversioninloworbit AntennaDiameter
• MillimeterWaveBeamingat220GHz AntennaDiameter
• UseTetheredAerostats EfficiencyThroughAtmosphere
• PowerExchangewithterrestrialrenewableenergy CosttoFirstPowerBarrier
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GirasolConverterSatelliteConceptualDesign
ConceptualDesignofa1‐GWConverterSatelliteWhatitmustdo?
• Receivelargequan;;esofdirectedsunlight,convert,andbeampowerasmillimeterwave
• Maximizeefficiencyofconversion• Minimizeheatthatmustberadiated
• Maximizespecificpower(powerbeamed/unitmass) launchcosts
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GasTurbinevs.BroadbandPVConversion
PotenAalforOrderofMagnitudeImprovementUsingGasTurbine
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GasTurbinevs.BroadbandPVConversion
• BroadbandPVscaleslinearly• SpecificPowerofHighIntensityPVarrayslimitedbyheatradia;onproblem
Why? SunIntensity=HeatThatMustBeRadiated= ATCSMass
FundamentalBroadbandPVissue:Broadbandenergymustpenetrateasolidsurfacelayerbeforephotonscandriveelectronsthroughthesemiconductorarray
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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
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Girasols
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ClosedHeliumBraytonCycle
Helium
• HighandConstantSpecificHeat• HighThermalConduc;vity
• LowMassFlowRateRequiredClosedHeliumBraytonCycleOperaAngInSpace
• Star;ngPoint:IntercooledHeliumBraytonCycleLiquidFluorideNuclearPowerPlantCycle(DOE‐ORNL)
• Eight125MWSec;ons–Dimensionssimilartojetengines
• Alloysexistthatcanmeet3650KOpera;ngTemperature
• Advantagesoverterrestrialjetengines:1. Predictabilityoforbit2. Noatmosphere3. Temperatureinspace
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GirasolTurbomachinery
1) 300m Collector 2) Intensified Feed 3) Heater 4) Compressor 5) Turbine and Generator 6) Radiator 7) Phase Array Antenna
Components:
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ThermodynamicCycleAnalysis
Efficiencies Based on Jet Engine Efficiencies
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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
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Mirasols
HighAlAtude(GEOorNearGEO),UltralightReflectorSatellitesdirectsunlighttogirasols• U;lizetechnologysimilartosolarsails
• Op;callinkingbetweenmirasols/girasols• Sunlightwavelengthsonorderofμm
veryli]lebeamdivergence,evenoverlargedistances
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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
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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
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TechnicalandEconomicResultsAnalysis:GirasolEffectonNPVTrough
Amount of Investment Required Reduced Significantly from Baseline
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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
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QuesAons?
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Backup
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