Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering A US-India Power Exchange Towards a Space Power Grid Brendan Dessanti, Nicholas Picon, Carlos Rios, Shaan Shah, Narayanan Komerath Daniel Guggenheim School of Aerospace Engineering, Georgia Institute of Technology ISDC 2011, Huntsville, AL May 2011

Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering Most of humanity does not get the $0.10/KWhe, uninterrupted electric power that we take for granted. Residents pay exorbitant costs for the first few watts or watt-hours and lack basic opportunities. A real-time power exchange through a Space Power Grid (SPG) will help terrestrial power plants become viable at ideal but remote sites, smooth supply fluctuations, and reach high-valued markets. With infrastructure and market established, 2 nd -gen SPG will add and expand SSP beyond 4TW. SPG architecture is viable at a healthy ROI, modest development funding, and realistic launch costs. The launch cost risk in GEO-based SSP architectures is exchanged for the R&D risk of efficient millimeter wave technology in the next decade. A US-India space-based power exchange demonstration is a first step towards SPG and SSP. 2 options for near-24-hour power exchange: 4 near-equatorial satellites at 5500km, with ground stations in USA, India, Australia and Egypt. 6 satellites in 5500 km orbits, with ground stations only in the US and India. Risk Reduction Roadmap Summary of the Paper

Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering 1.SSP is an old dream 2.SSP is hard 3.See Space as the way to synergy with terrestrial 4.SPG Phase 1 5.SPG to full SSP 6.US-India collaboration for SSP is a new opportunity 7.Startup: India-US 8.India-US with Japan, Australia, North Africa 9.Challenges A US-India Power Exchange Towards a Space Power Grid

Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering We all Love SSP: Update on Space Solar Power from New Scientist, ~2008 Magazine: Dec

Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering 1.SSP is an old dream 1.Arthur C. Clarke: ET Relays, GEO opportunities: st artificial satellite, 1950s 3.Peter Glaser (Arthur D. Little Co) GEO SSP architecture: NASA/ASEE Space Settlement study, NASA/DOE. NASA TM81142, SAIC Fresh Look: NAS , SPS2000 JAXA/NASA, 1992-present 8. “Gold Rush to LEO” 9. JAXA LEO demo wide-area beaming proposal 10. India-US Strategic Partnership (Garretson, 2010) SLI? Heavy Lift? Commercial Launch Moon-Mars SLI? Heavy Lift? Commercial Launch Moon-Mars Beyond Apollo? Case for Space Shuttle: 1000s of launches at $100/lb to LEO Beyond SkyLab? STS? ISS? Global Warming, Peak Oil, Etc.

Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering NASA ESA JAXA RKA Millimeter Wave Specific Power LAUNCH COST PV Efficiency 2. SSP is Hard

Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering Receiving antenna size for 84% capture vs. beam distance Transmitter Diameters: Laser: 10m. Mmwave: 150m Must bring down the Specific Mass in Orbit, and ground infrastructure size Beyond 10 GHz, beaming is affected severely by moisture Lasers offer small receiver size, but are banned in space Come Down From GEO, Use Millimeter Wave Beaming Log 10 (Receiver Dia, m) Beam distance, 1000s of kilometers 2000kmGEO No government will invest $$T in SSP before 1 st revenue, when terrestrial energy options exist (solar, nuclear fission, fusion, distributed renewables). $1T will not get to 1 st power by GEO-based SSP – and will not lead to scale up to TW levels.

Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering P: price of space-generated power in (e.g. $0.2/KWHe)  : 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., $2500/kg) Prospect of Breakeven: k ~1 ParameterPresentNeeded P, US$/ KWHe  ?? (0.1?)0.5 c, $/kg to LEO$2K - $15K<$2.5K s, Kwe/Kg in space<0.1>1 Ground receiver dia~ 100km<1km Technical barriers: , s

Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering Space Power Grid Approach to SSP Phase 1 Revenue by beaming terrestrial power to terrestrial and space-based customers. Trades launch cost risk of GEO-based SSP against technology risk of mmwave. Constellation of 100 relay sats at 2000km trading with 250 ground stations. 220 GHz mmwave. System breaks even inside 17 years with fairly realistic parameters. (17-yr R&D window for SSP conversion technology) Phase 2-3: High-orbit (MEO) collectors beaming sunlight to Converters at 2000 km orbits. Economically viable ramp-up to 4TW or beyond.

Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering Afternoon Sun Scenario for SPG Phase 1 startup. 80 minutes of access per 24 hours per location. This orbit performs 23 revolutions around the earth every 48 hours. Ground Tracks of 6 sun-synchronous satellites at 1900 km

Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering Space Power Grid Architecture ParameterPhase 1 Relay sat 1GWe Converter /Relay “Girasol” Reflector, per Gwe “Mirasol” Dry Mass, kg2680 Total Mass, kg ,00053,000 Array dia, m50150 Orbit height, km 2000 (5500) 2000>10,000 Packed length,dia, m 4.6, 2.2 m?? Launcher classDelta IIOn-orbit assembly Heavy lift

Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering SPG model results Phase 1: SPG: Helping Terrestrial Plants Phase 2&3: Towards full SSP Phase 2&3 tradeoff between installation rate and investment

Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering SPG BASELINE RESULTS COMPARED TO JPL “HALO” GEO REFLECTOR/CONVERTER ARCHITECTURE SPG ~ 0.9 kg/KWe in orbit, most of it in 2000Km orbits HALO ~ 10.9 kg/KWe in orbit, all of it in GEO HALO Orbital mass driven by Converter mass of ~ 3Kg/KWe and GEO-based 2.45GHz transmission PV arrays ~ 1kg/KWe shown possible at small scale. Brayton Cycle converter ~ 0.4 kg/KWe possible at large scales: Technology risk

Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering US-India Demonstration Model Demonstrate feasibility of beaming power using few satellites and ground locations. Model development using STK Orbit-modeling software Model characteristics: 5500 km altitude, 3 to 6 satellites (near-equatorial orbits) – 4 ground facilities: India (near Mumbai), US (NM), Middle East (near Cairo), Western Australia – 2 facilities (India & US)

Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering 6 Satellites, 4 Ground Stations4 Satellites, 4 Ground Stations

Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering 6 satellite, US-India

Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering 1. Dynamic power beaming between a ground station and a satellite in a sun-synchronous orbit. 2. Terrestrial and earth-space-earth millimeter wave beaming at progressively higher frequencies, culminating in a 220GHz system. 3. Millimeter wave conversion efficiency improvements 4. “Burn-through” techniques to improve transmission efficiency 4. Millimeter wave power beaming between satellites. 5. Waveguide type relay of millimeter wave power through a satellite to another satellite in space. 6. A 2-satellite, 2-ground station relay of millimeter wave power. These will then lead naturally to the 6-satellite and 4-satellite systems describe above, growing from there to the full SPG. POSSIBLE SEQUENCE OF ADVANCEMENTS / DEMONSTRATIONS

Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering 1. Renewed interest in SSP must be viewed with healthy skepticism, but careful analysis of opportunities. 2. The scale of the SSP system needed to reach 4TWe of space-based power generation poses immense difficulties requiring new approaches. 3. To make SSP viable, improvements are needed in specific power, beaming efficiency, and launch cost. 4. Millimeter wave beaming and orbits at 2000 km in a Space Power Grid architecture, can provide order-of-magnitude improvement in viability. 5. Primary gas turbine power generation may close the specific power viability gap, when used with SPG. 6. A US-India power exchange provides a unique opportunity to start the Space Power Grid towards full SSP. 7. With 4 or more nations participating, it is possible to set up nearly continuous power exchange with 4 to 6 satellites in 5500 km orbits. 8. With only the US and India participating, a constellation of 6 satellites suffices to demonstrate a continuous power exchange. CONCLUSIONS

Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering The senior author (NK) is supported by the NASA “EXTROVERT” initiative to develop cross-disciplinary innovation resources and concept explorations. Mr. Tony Springer is the technical monitor. ACKNOWLEDGEMENT

The Mouse on the Moon (1963) The Grand Duchy of Grand Fenwick is picked by the U.S. and USSR as a showpiece for the Internationalization of Space Research. While the Grand Duke is dreaming of gold toilets and hot baths, their (mad) Professor, the Prince and his smart Fiancee are slapping together a rocket. The U.S. and Soviets get into a desperate race to beat Fenwick to the Moon. “When Did You Know?” Lesson: Mad professors and enthusiastic students must scrounge from International Grand Agendas and solve problems, so that governments eventually get serious. d-wibberley/mouse-on-moon.htm

Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering Impact of rain and fog: Millimeter wave regime is bad. Need “burn-through”. 220GHz 94GHz

Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering

Dry Atmospheric Absorption for Vertical Transit

Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering Line A: Average absorption at sea level, 20C, 1atm, H2O vapor 7.5 g/m3) Line B: Altitude 4 kilometers pressure altitude, (0C, Water Vapor Density= 1 g/m3) Atmospheric Absorption for Horizontal Propagation

Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering Atmospheric Transmission in the GHz regime

Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering

Mirasol: High Orbit Ultralight Collector/Reflector In Constant View Of The Sun, Focusing On to Collector/Converter/Relay Sats in Low Orbits excellent.jpg

Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering Girasol: 1 GWe Intensified Collector/Converter/Relay In 2000km / Other Orbits

Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering SSP is hard Why SSP? Why has it Remained a Dream? Feature SSPGround-based solar power Steady generation 24 hour, year-round. ~12,000KWh/m^2 per yr Daily /seasonal/ weather fluctuations. Average ~900 to 2,300 KWh/yr Waste heatDissipated in SpaceReleased on Earth Transmission efficiencyLow, weather-dependentHigh, independent of weather (see above) Receiver/distributor Infrastructure size Massive for GEO sats due to beam width, for any power level Scalable from rooftop to Sahara size Generator sizeMassive for GEO sats.Scalable Installation cost per watt Very high due to GEO launch cost Moderate

Micro Renewable Energy Laboratory, Georgia Institute of Technology, Daniel Guggenheim School of Aerospace Engineering SPG BASELINE ASSUMPTIONS COMPARED TO JPL “HALO” GEO ARCHITECTURE