Generating electricity in space to power our future generations

Imagine a world where clean, renewable energy is available 24/7, unaffected by weather conditions or the day-night cycle. This is the true promise of space-based solar power (SBSP). It encompasses a revolutionary approach to energy generation that captures solar power in space, converts it to electricity and beams it to Earth. By offering a reliable, efficient, and sustainable power source, SBSP has the potential to reshape the energy landscape as we know it today.

SBSP works by capturing solar energy in space using satellites equipped with large solar panels. The generated electricity is converted into high-frequency microwaves and transmitted wirelessly to Earth. On the ground, special receiving stations called rectennas capture these microwaves and convert them back into electricity, which can then be fed into the power grid.

The idea of using satellites to collect energy from the sun and beam it to Earth is more realistic than it might sound. The technologies needed for the concept already exist in Earth-based applications such as solar panels, microwave ovens and radio receivers.

Recent technological advancements in three key areas have made SBSP more feasible than ever before:

Space robotics and autonomous systems are enabling the construction and maintenance of large solar arrays in space. These robotic systems can operate in the harsh environment of space, assembling and repairing solar panels without the need for human intervention.

At first glance, investing in SBSP may seem unnecessary, given the affordability and scalability of terrestrial solar and wind energy. However, SBSP addresses key limitations of Earth-based renewables and offers several compelling advantages:

• Uninterrupted 24/7 energy supply*: SBSP operates in geostationary orbit, delivering continuous, weather-independent power. This makes it a more scalable, and potentially safer alternative to nuclear energy for providing reliable baseload power.
• Enhanced energy resilience: SBSP can provide energy to remote and critical locations, such as forward operating bases, disaster relief zones, or areas with limited infrastructure, reducing dependence on vulnerable supply chains during crises. However, to assess its practicality, it's important to compare the size of rectennas to terrestrial solar panels to determine how much solar has to be collected to have a similar amount of energy.
• Clean energy production: SBSP is expected to demonstrate a low lifecycle emissions intensities among energy technologies, with levels estimated below 10 gCO₂eq/kWh according to NASA. This positions SBSP as a highly clean and sustainable energy option.
• Cost competitiveness and long-term viability: In a best case scenario, SBSP is projected to reach a Levelized Cost of Energy (LCOE) as low as $0.03–$0.08/kWh by 2050, comparable to the cheapest terrestrial renewables. Advances in reusable rockets, solar efficiency, and orbital hardware durability are driving down costs, moving SBSP closer to becoming a viable large-scale energy solution.

In summary, SBSP doesn’t necessarily compete with terrestrial renewables, it complements them. By solving challenges like weather-dependency and grid reliability, SBSP positions itself as a transformative technology for a resilient energy future.

*Satellites in GEO orbit are continuously exposed to sunlight, except during occasional solar eclipses. They spend less than 1% of their time in the Earth's shadow. 

Although there are no major showstoppers preventing SBSP from becoming a reality, there are challenges to overcome. Sia Partners has identified a non-exhaustive range of challenges across various categories:

Technological challenges

• Wireless Power Transmission (WPT) conversion efficiency: although the concept of transmitting energy via laser beams has been proven already, the application of the technology in space has not been tested extensively. Caltech has demonstrated this concept in 2023, albeit only at a very small scale. As the efficiency of WPT declines significantly as range increases, driven by beam misalignment and atmospheric interference, there are some challenges still to be overcome.
• Propulsion technology: currently, the most effective method (# launches, emissions, production costs) to deploy a full-scale SBSP system is by launching its sub-systems to Low Earth Orbit (LEO) by a reusable launch vehicle.  After assembly in LEO is complete, the whole system would need to be ‘tugged’ or independently propelled through Electrical Propulsion (EP) to Geostationary Earth Orbit (GEO). Although this is a proven concept for many GEO satellite operators, it has never been done before for a large-scale system. Recent innovations in EP technology (e.g. ion – and Hall Effect thrusters) have been revolutionary for station-keeping and deep space missions, SBSP systems would require propulsion that features higher peak thrust, enabling the transport from LEO to GEO and trajectory corrections during its remaining lifespan. Concepts like VASIMR (Variable Specific Impulse Magnetoplasma Rocket, a specific impulse plasma thruster that can be used specifically in space) show promising signs but still need to be tested for large-scale platforms.
• Materials: because systems operating in GEO experience harsher conditions (e.g. temperature, radiation, micrometeoroids, etc.) than in lower orbits, SBSP systems need to be manufactured from durable, yet ultra-lightweight materials. As current GEO-orbiting satellites have an average lifespan of 10 to 15 years and the projected lifespan of SBSP-systems is estimated to be 25 to 30 years, two refurbishment cycles are required. Innovation on this topic could potentially extend the lifetime to 15 years, which would significantly decrease maintenance costs.
• Conversion efficiency of PV cells: the current gap between state of practice and state of the art of solar cell conversion efficiency in space is 37%*. And although the current lab-tested record is 44.5% (AM0), this indicates that there is still a lot of room for improvement. As increasing conversion efficiency decreases the size and mass of an SBSP system (for the same output power), this would also decrease the hardware development, assembly costs, number of launches, and ultimately the emissions.
• In-space servicing, assembly, and manufacturing (ISAM): for the assembly of a large-scale SBSP system that measures 19km² (RD2), robust ISAM capabilities are a must. While some commercial ISAM capabilities exist (e.g., Northrop Grumman for GEO satellites), the market remains unproven, with many technologies yet to be space-tested and requiring adaptation for large-scale systems.

*Current state of practice = 33%; state of the art = 70%, according to Nasa SBSP study, January 11, 2024.

Economical challenges

• Scaling High-Cadence Heavy Lift Launches: SBSP faces a sole reliance on (reusable) Super Heavy Lift launch Vehicles (SHLVs) to transport all sub-systems to the required orbit. At the moment of writing, only the USA (Starship), Russia (Yenisei) and China (Long March 9) are developing SHLVs with a payload capacity that exceeds 100 tons to LEO. Since launch costs constitute the single largest expense for SBSP, achieving high-frequency launch cadence to drive down costs is essential.
• High CAPEX for support infrastructure: to accommodate the required number of SBSP launches per year, it is estimated that Starship alone would require a five to 10-fold increase in spaceport infrastructure according   to the NASA SBSP study . Add to that the CAPEX for the building the rectenna, transformers, transmission lines and other support infrastructure, it becomes abundantly clear that significant funding will be needed. 
• Securing funding: to secure that level of funding, Sia Partners observes opportunities for public-private partnerships (PPP). By partnering with governments, potential private operators (energy suppliers) will be able to mitigate risks, get access to government expertise, and enhance public support.

Regulatory challenges

• Spectrum allocation: as the radio spectrum is a finite resource and it is already crowded with other applications (e.g. telecommunications, radar, …), it requires international coordination. Additionally, there are concerns about the impact of SBSP transmissions on other satellites, especially those that are operating in a lower orbit.
• Space traffic management: similar to radio spectrum allocations, orbital slots for satellites need to be allocated as well. Due to the increased congestion in space and the vast size of a future SBSP system, international coordination will be necessary to adequately manage space traffic.
• Governance & Security: since these systems would operate across boundaries, yet rectenna’s would be stationed within a single country, international agreements are required for the ownership & governance of a SBSP-system. On top of that, as an SBSP system would be considered as critical infrastructure, careful consideration should be given to its physical and virtual (e.g. cyber) security.
• Active debris removal: a large-scale SBSP-system would be both a contributor and a victim of space debris. Namely, due to its size, it would struggle to avoid incoming projectiles (steroids, satellites, etc.). If hit by a big enough projectile, this collision could lead to a cascading debris reaction, whereby debris of the SBSP-system would create new collisions, which would create new debris, and so on. To mitigate this, future operators and governments should cooperate to actively remove debris that is currently a threat to SBSP deployment.

Environmental challenges

• Land management: large tracts of land will need to be acquired to build the required rectenna’s, extra spaceports, production & assembly facilities, energy infrastructure, potentially impacting local ecosystems and communities.
• Decommissioning strategy: the most common strategies to decommission a satellite or any other space vehicle today is to move it to a ‘graveyard-orbit’ or to ‘crash-land’ in a desolate part of the Pacific Ocean. Both scenario’s pose great environmental risks and are not the best course of action for such a vast system as SBSP. Developing new decommissioning strategies, like in-orbit deconstruction, could prove to be a solution.
• Impacts of power beaming: microwave or laser energy beams could potentially pose risks to humans, animals or ecosystems on earth. Besides, it could also cause atmospheric or ionospheric interactions in space that we do not know the consequences of.

SBSP is poised to become a crucial component of the global energy mix, providing a sustainable solution to the growing demand for clean energy. Here are three key takeaways:

• Early Adopters: A key advantage of SBSP technology is its ability to provide energy to remote and rural locations where a rectifying antenna can be installed on Earth. For example, military forward operating bases (FOBs), which require reliable, independent power sources, are an ideal use case. Early adopters, such as these, are crucial not only in demonstrating the feasibility of SBSP but also in driving innovation and refining the technology.
• Commercial Expansion: As technology matures and costs decline, SBSP is set to expand into commercial and public applications, offering a significant boost to global decarbonization efforts. Large-scale adoption of SBSP can transform the energy landscape, providing a stable power supply and minimizing the reliance on expensive flexibility measures needed to address the intermittency of renewables.
• European space industry: In regions like Europe, where affordable heavy-lift or frequent space launches are still developing, an SBSP deployment program could spur the creation of a European super heavy-lift rocket. This would help reduce costs and drive progress across the entire European space industry.

The findings of Sia Partners suggest that space-based solar power has the potential to become an integral part of the future energy mix, addressing global energy demands while contributing to a more sustainable and resilient energy ecosystem.

Sia Partners offers various services to help you explore​ the potential of transformative technologies such as SBSP​. Curious to find out how we can help?