Millimeter Wave Space Power Grid Architecture 2011 Nicholas Picon Brendan Dessanti Shaan Shah Richard Zappulla Narayanan Komerath Experimental Aerodynamics and Concepts Group School of Aerospace Engineering

Conference Papers from Our Team B. Dessanti, R. Zappulla, N. Picon, N. Komerath, “Design of a Millimeter Waveguide Satellite for Space Power Grid” N. Komerath, B. Dessanti, S. Shah, “A Gigawatt-Level Solar Power Satellite Using Intensified Efficient Conversion Architecture” N. Komerath, B. Dessanti, S. Shah, R. Zappulla, N. Picon, “Millimeter Wave Space Power Grid Architecture 2011”

Outline Introduction Space Solar Power Background The Space Power Grid Architecture Aerostats Proposed US-India Demonstration as a First Step System Assumptions and Parameter Choices Technical and Economic Results Analysis Conclusions

Introduction The Dream of Space-Based Solar Power (SSP): Deliver cheap, limitless, clean, quiet electric power to the world Factors Driving Cost and Difficulty of SSP Magnitude of the Problem – Cost to First Power Specific Power – The power that must be generated per unit mass placed in orbit Relationship between orbit height, beam frequency, and receiver size Launch Costs – Cost to place mass in orbit

Space Solar Power Background Space-Based Solar Power is an old dream Arthur C. Clarke – 1945 – benefits of GEO Peter Glaser – 1968 – Patent for GEO based SSP arch. NASA/DOE Study – Late 1970s NASA “Fresh Look” Study – 1997 NASA SERT – 1999 Proposed JAXA LEO Demo Etc…. Recurring Conclusion: No Technical Show Stoppers Significant Improvements Needed for Economic Viability New Scientist Magazine SSP Illustration

Space Solar Power Background: Traditional Approaches Geosynchronous Earth Orbit (36000km altitude) Pros: No dynamic beam pointing necessary Cons: Distance drives spacecraft size, immense launch costs, no evolutionary approach possible, requires large initial investment Microwave Beaming Pros: Atmospheric transmission efficiency, low technology risk Cons: Transmitter/Receiver Size Photovoltaic Panels for Collection Pros: low technology risk Cons: Specific Power, Linear Scaling

SSP Architecture Analysis: Viability Parameter How much improvement do we need? Prospect of Breakeven: k ~1 P: price of space-generated power in (e.g. $0.2/KWHe) h: efficiency of converted power transmission to the ground. (e.g. 50%) s: (KWe/Kg): Technology of conversion, giving mass needed per kilowatt of electric power generated in space. (e.g., 1 KWe/kg) c: Launch cost in $ per kg to Low Earth Orbit. (e.g., $2500/kg) Technical barriers: h, s Parameter Present Needed P, US$/ KWHe 0.1-0.2 0.2 h ?? (0.1?) 0.5 c, $/kg to LEO $2K - $15K <$2.5K s, Kwe/Kg in space <0.1 >1 Ground receiver diameter ~ 100km <1km

Space Power Grid Architecture The Bottom Line: According to our analysis, a roughly 100x improvement in viability is needed for SSP to become a reality Is this possible? “Flash Drive” Argument (mass production collapses cost) Our approach: Trade the launch cost risk of GEO-based systems for technology risks associated with SPG

Space Power Grid Architecture Deviations from Traditional Approaches Use Primary Brayton Cycle Turbomachine Conversion of highly concentrated sunlight (InCA: Intensified Conversion) Specific Power, s Separate the collection of sunlight in high orbit from conversion in low orbit Antenna Diameter Millimeter Wave Beaming at 220GHz Use Tethered Aerostats Efficiency Through Atmosphere Power Exchange with terrestrial renewable energy Cost to First Power Barrier

Space Power Grid Architecture Relationship between beam distance, frequency, and receiver diameter:

Beam Distance and Frequency Comparison Assume equal receiver size (100m), equal antenna specific mass (0.05 kg/m^2), assume equal beam capture (84%): Parameter GEO, 5.8 GHz 2000km alt., 220 GHz Reduction Beam Distance, R 35,786 km 2,000 km 17.9x Wavelength, λ 51.7 mm 1.36 mm 37.9x Transmitter Diameter 45.2 km 66.5 m 679x Antenna Area 1.60e9 m^2 3478 m^2 460633x Antenna Mass 8.01e7 kg 174 kg

Space Power Grid Architecture Phase I Constellation of LEO/MEO Waveguide Relay Sats Establish Space as a Dynamic Power Grid Phase II 1 GW Converter Satellites – “Girasols” Gas Turbine Conversion at LEO/MEO Phase III High Altitude Ultra-light Solar Reflector Satellites – “Mirasols” Direct unconverted sunlight to LEO/MEO for conversion

Aerostat System Millimeter Wave Beaming Poor Through Rain and Fog

Aerostat System Possible Solution: Use Tethered Aerostats

Proposed US-India Demonstration A demonstration model for terrestrial power exchange between the US and India was designed to illustrate the benefit and feasibility of the Space Power Grid concept The two countries were chosen based on the US and India’s high energy production and usage and because of the new Indian-US collaboration as prompted by President Obama and Prime Minister Singh Model highlights the possibility of selling energy to the partner country at non-peak usage times

US-India Demonstration

US-India Demonstration 6 Satellite – 2 Facility System Designed to provide 24 hr. access beaming capability between Mumbai, India and Las Cruces, NM Satellites at fixed angles in relation to one another, simplifying the problem of satellite to satellite beaming

System Assumptions and Parameter Choices Key Assumption: Launch Cost Current Launch Cost Rate: >$10,000/kg Other Architectures argue for $100-200/kg Our calculations assume reasonable reductions

Systems Architecture Economic Analysis Breakeven Point: when NPV=0 at specified ROI (6%) from Phase I startup Baseline SPG System (March 2011) vs. Current Architecture Using system assumptions in previous slide 5 year dev. period before 1st Satellite Launch Attempt to reach 4TW of power capacity Attempt to demonstrate Phase 1 breakeven within 17 years Constraint to demonstrate total architecture breakeven within 50 years relaxed In March 2011, Phase 2 assumed to start after Phase 1, in this paper we investigate beginning Year 12 Ramp rate constrained by infrastructure building limitations

Technical and Economic Results Analysis: Breakeven vs. Selling Price 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

Technical and Economic Results Analysis: NPV Trough Phase 1 Full Architecture Amount of Investment Required Reduced Significantly from Baseline

Architecture Analysis Summary and Conclusions Technical Risk and Uncertainties in Mass and Efficiency in developing mmwave conversion and beaming are main risks to SSP development. Phase 1 SPG addresses these before large 1 GW converters launched. Phase I Waveguide Satellite and Phase II Girasol Mass Estimates Come in Under Previous Estimates used in SPG architecture reduced uncertainty. Overlapping Development of Phase I and Phase 2 is considered to reduce deployment time of large scale SSP Updated architecture can achieve breakeven by Year 31, with NPV trough <$3T, at $0.11/kWh At given ramp rate, SSP can reach > 5.6 TW by Year 50 Assumes value of unity for k viability parameter

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