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Space Solar Power for Global Decarbonization

Unconventional technologies are needed to achieve worldwide decarbonization goals while meeting growing demand for affordable, reliable, secure, and resilient energy. With an eye toward the sky, EPRI is exploring the status and potential of space-based solar as a baseload generation option for terrestrial electricity grids.

EPRI Insights | February 2024

EPRI is monitoring space solar develop- ments and exploring potential oppor- tunities for electric sector engagement. This may involve defining owner/oper- ator requirements, developing utility use cases, and demonstrating key compo- nents and integrated systems.

Research Question (click) Technolog Insights (click) Scaling Challenges (click) Initial Takeaways (click) Space Solar Technology Timeline and Roadmap (click) Next Steps (click)

TECHNOLOGY INSIGHTS

RESEARCH QUESTION Photo-voltaic (PV) technology supplies low-cost, carbon-free energy, but solar variability creates needs for backup electricity generation or energy storage.need The Sun shines continuously in space, and current launch vehicles can deliver satellite payloads of unprecedent size into orbit at reasonable cost. Can space-based solar power plants beaming energy down to the Earth’s surface make meaningful contributions to global decarbonization by 2050?

SCALING CHALLENGES

NEXT STEPS

Crystalline silicon PV created to power early satellites today supplies low-cost energy to consumers and the grid. In geostationary orbit (GEO), the Sun never sets, atmosphericpheric losses are zero, and the weather is always clear. Novel PV materials and devices are expected to deliver much higher efficiency plus unprecedented pro

INITIAL TAKE-AWAYS

SPACE SOLAR TECHNOLOGY TIMELINE AND ROADMAP

This timeline and roadmap are based on “Key Sources” below. Current and future TRLs are consistent with expert assessments, which assume adequate public-private R&D investment for 20-plus years. EPRI has not independently assessed space power TRLs.

Project Communication

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Project Support

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Project Coordination

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History 1941-2020

• 1941: Microwave power beaming from space to Earth described by Isaac Asimov • 1963-64: Integrated beaming system (100 W over 5.5 m) and beam-powered helicopter flight (10 hours at 15.2 m altitude) demonstrated in laboratory by Raytheon and US Air Force • 1968: Integrated space power system with ground rectennas described in Science • 1975: Ground-to-ground beaming record set (34 kW over 1.5 km) by Raytheon and NASA • 1987: Beam-powered plane flight demonstrated (20 minutes at 150 m altitude) by Universityof Toronto and Communications Research Centre Canada • 1993: Power beaming between space-based antennas and rectennas demonstrated by Kobe University, Kyoto University, and Japan’s Institute of Space and Astronautical Science • 2020: Sandwich tile integrating PV generation and microwave conversion modules demonstrated in LEO by US Naval Research Laboratory (NRL)

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1941: Microwave power beaming from space to Earth described by Isaac Asimov 1963-64: Integrated beaming system (100 W over 5.5 m) and beam-powered helicopter flight (10 hours at 15.2 m altitude) demonstrated in laboratory by Raytheon and US Air Force 1968: Integrated space power system with ground rectennas described in Science 1975: Ground-to-ground beaming record set (34 kW over 1.5 km) by Raytheon and NASA 1987: Beam-powered plane flight demonstrated (20 minutes at 150 m altitude) by Universityof Toronto and Communications Research Centre Canada 1993: Power beaming between space-based antennas and rectennas demonstrated by Kobe University, Kyoto University, and Japan’s Institute of Space and Astronautical Science 2020: Sandwich tile integrating PV generation and microwave conversion modules demonstrated in LEO by US Naval Research Laboratory (NRL)

Space solar advances from TRL1 to TRL5. Space-based capabilities and HISTORY components are at lower TRLs, relative to needed orders-of-magnitude increases in beaming power and distance.

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Space power systems integrate satellite-based solar energy capture and conversion with wireless power transmission to ground-mounted, grid-tied rectifying antennas (rectennas). Governments and technology developers envision gigawatt-scale space power plants as potentially competitive baseload resources by 2050.

The space solar concept emerged in the late 1960s as a possible commercial spinoff from the race to the Moon. Significant NASA investment, spurred by the oil crisis, led to power beaming records achieved in 1975 but not surpassed since. R&D interest waned due to cost barriers driven by limitations on launch capabilities.

Commercial launch platforms suitable for building large solar satellite arrays now exist, and low-Earth-orbit (LEO) testing of prototype components is under way. Current R&D focused on defense applications of autonomous airborne vehicles and resilient energy networks is advancing long-distance power beaming technology.

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EPRI’s 1992 techno-economic assessment identified wireless, satellite-based power transmission as a plausible 21st century solution for serving distant load centers.

As of 2023, challenges to space solar revolve around scale-up of components and integrated systems—first for terrestrial uses, then in space— to enable safe beaming at grid-relevant power levels over distances of hundreds to thousands of miles.

Space Solar: Satellite-based systems will likely employ optical devices to focus solar energy on multi-junction, thin- film PV cells and modules designed and tuned to maximize electricity production under space conditions. Key technical challenges: fabricating multi-gigawatt arrays in space.

Power Beaming & Ground Reception: Microwaves, rather than lasers, likely will be used based on safety considerations. Electricity-to-microwave conversion will occur within individual PV modules or at central generators within arrays. Earth-based rectennas, employing guide beams to ensure safety, could be smaller than today’s gigawatt-scale PV plants. Key technical challenges: increasing power level, transmission distance, and end-to-end efficiency.

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Space solar is at a technology readiness level (TRL) of 5 based on LEO validation of lab scale components. System integration and scale-up demonstration are next steps. Leading R&D groups include space/defense agencies and contractors in China, Japan, US, and UK, plus California Institute of Technology and startups emerging globally. Europe is undertaking a new R&D initiative through the European Space Agency (ESA).

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COST & SPECTRUM

Power beaming at 2.45 and 5.8 GHz is efficient and can be done safely, offering low atmospheric losses and the ability to meet international standards for human exposure. However, these microwave frequencies lie within bands used for low-power wireless communications, creating electromagnetic interference risks. Building public acceptance and securing dedicated spectrum are additional priorities for space solar commercialization.

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COST

"According to 2022 ESA and UK studies, government investment is essential to de-risk space solar and enable baseload plants deployed from 2040-50 to compete with variable solar and wind and to offer significantly lower levelized cost of electricity than other dispatchable resources over a 30- year lifetime. Cost projections are highly dependent on mass in GEO, putting a premium on R&D to increase power-to- mass (W/kg) ratio.

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STATUS

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Space solar advances from TRL1 to TRL5. Space-based capabilities and components are at lower TRLs, relative to needed orders-of-magnitude increases in beaming power and distance.

Space solar could achieve TRL6-7 as China, European nations, US, and others conduct scale-up validation testing and demonstrate integrated systems on the ground and in space.

2032-35, SEI: Pilot-scale system from GEO to ground (500 MW) 2035, CAST: Pilot-scale system from GEO to ground (10 MW) 2035, AFRL & NRL: Full-scale prototype serving ground bases 2035-39, SEI: Full-scale first-of-a-kind plant serving the grid (2 GW)

Space solar could achieve TRL9 as industrialized and automated processes enable replicate deployment of gigawatt-scale plants to help meet net-zero targets and global energy needs.

Terrestrial Demonstrations & Deployments Ongoing, US Air Force Research Laboratory (AFRL): Packing, deployment, and assembly of large structures Ongoing, NRL: Ground-ground, groundair, and air-ground beaming at greater power levels, efficiencies, and distances 2028, UK Space Energy Initiative (SEI): High-power beaming from stratospheric platform to ground rectenna Pre-2030: Defense/commercial applications for remote power supply

Space Demonstrations 2023, AFRL: Variable emissivity materials for thermal management 2025, AFRL & NRL: Prototype sandwich tiles and beam shaping methods from LEO to ground rectenna 2028, China Academy of Space Technology (CAST) and 2030, SEI: Integrated pilot-scale LEO systems beaming intermittent power to ground 2030, AFRL & NRL: Subscale LEO systems serving ground bases 2030, CAST: Pilot-scale system beaming continuously from GEO to ground (1 MW)

Space solar could advance to TRL8 as integrated systems are launched, lifted, built, and applied to supply baseload power for terrestrial uses.

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HISTORY

2021 - 2030

2030 - 2040

2041 - 2050

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About EPRI Founded in 1972, EPRI is the world's preeminent independent, non-profit energy research and development organization, with offices around the world. EPRI's trusted experts collaborate with more than 450 companies in 45 countries, driving innovation to ensure the public has clean, safe, reliable, affordable, and equitable access to electricity across the globe. Together, we are shaping the future of energy.

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