Space-Based Solar Power: A Game-Changer or Just Hype?

12-06-2023 | By Robin Mitchell

Recently, researchers from Caltech demonstrated what they claim is the first time power has been gathered in space and beamed to Earth, creating plenty of media hype. This demonstration is part of Caltech's Space Solar Power Project (SSPP), an ambitious initiative aiming to harvest solar power in space and transmit it to Earth's surface. However, when looking into the story, there is nothing ground-breaking about this announcement, and if anything, it proves that gathering power from space is not exactly the best of ideas. What did the researchers announce, why is it nothing but hype, and what alternatives would be better?

Researchers claim wireless power transmission in space

Recently, researchers from Caltech announced that they have, for the first time, demonstrated wireless energy transmission in space. Furthermore, the researchers also noted that they were able to receive energy collected from space and sent down to Earth, demonstrating that wireless energy transfer from space is possible.

The researchers from Caltech have made a significant stride in the field of space-based power generation. They launched a small satellite, the Space Solar Power Demonstrator (SSPD-1), equipped with a Microwave Array for a Power-transfer Low-orbit Experiment (MAPLE). This system, composed of light and flexible microwave transmitters, converts electricity from solar panels into microwave energy. This energy is then transmitted to a receiver on the same satellite, converting the microwave energy back into electricity. The use of lightweight materials for the transmitter is a thoughtful design choice, aiming to reduce the overall weight of the satellite and allow for easy deployment. One of the key challenges for the SSPP is the need for the power transmission arrays to be lightweight to minimize the amount of fuel needed to send them to space, flexible so they can fold up into a package that can be transported in a rocket, and a low-cost technology overall.

The MAPLE system was developed by a team led by Ali Hajimiri, Bren Professor of Electrical Engineering and Medical Engineering and co-director of SSPP. It uses an array of flexible lightweight microwave power transmitters driven by custom electronic chips built using low-cost silicon technologies. The array of transmitters can beam energy to desired locations, making it a crucial component for the feasibility of the SSPP.

Interior of MAPLE showing transmission array on the right and receivers on the left, captured in a photo from space (Credit: SSPP)

The interior of MAPLE, showing the transmission array on the right and the receivers on the left, captured in a photo taken from space. (Credit: SSPP)

To delve a bit deeper into the technology behind wireless energy transmission in space, it's important to understand the role of microwaves in this process. Microwaves, a form of electromagnetic radiation, are capable of carrying energy over long distances. In the case of the SSPD-1, the solar panels convert sunlight into electricity, which is then converted into microwave energy by the MAPLE system. This microwave energy can be directed towards a specific location, such as a receiver on Earth, where it is converted back into electricity. This process, while seemingly straightforward, involves a complex interplay of electrical engineering and physics principles. 

The recent demonstration of the technology showed small LEDs on the satellite being powered via wireless energy transfer from the transmitters to the receivers that were separated by around 30cm. Furthermore, the researchers were also able to tune the transmitters to direct energy towards Earth, whereby researchers successfully recorded energy reception.

Ali Hajimiri, Bren Professor of Electrical Engineering and Medical Engineering and co-director of SSPP, shared his insights on the project, stating, 'Through the experiments we have run so far, we received confirmation that MAPLE can transmit power successfully to receivers in space.' This statement not only underscores the success of the experiment but also highlights the potential of this technology for future space missions and renewable energy generation. It's a testament to the potential of space-based solar power as a viable source of renewable energy, opening up new possibilities for exploration and scientific discovery.

On the satellite was another experiment called ALBA, which integrated 32 different solar cell technologies to analyse which cells perform the best in space. With such data, it will be possible for future missions to maximise energy generation from sunlight, thereby increasing the efficiency of solar-based power stations.

Power detection from MAPLE conducted on the roof of Moore Laboratory, credited to Ali Hajimiri.

Power detection from MAPLE on the roof of Moore Laboratory, credited to Ali Hajimiri.

While it's true that the researchers' demonstration of wireless power transmission in space is not a groundbreaking first, it's important to acknowledge the potential benefits of this research. For one, the technology could play a crucial role in future space missions, providing a reliable source of power for satellites and other space-based infrastructure. This could open up new possibilities for exploration and scientific discovery. Space solar power provides a way to tap into the practically unlimited supply of solar energy in outer space, where the energy is constantly available without being subjected to the cycles of day and night, seasons, and cloud cover—potentially yielding eight times more power than solar panels at any location on Earth's surface. 

This demonstration is a significant milestone in the ongoing efforts to develop space-based solar power systems. The Caltech team's research aligns with broader initiatives focused on exploring the feasibility and viability of space-based solar power. Scientists and engineers around the world are actively exploring various approaches to harnessing solar energy in space and transmitting it to Earth. The ultimate goal is to establish a sustainable and reliable source of renewable energy that can supplement terrestrial solar and wind farms. The Caltech demonstration contributes valuable insights and progress to this collective endeavour.

Why is this story nothing but hype?

It comes as no surprise that multiple media sites have picked up on this story and gone straight to print on how it will revolutionise the future of renewable energy. With space being empty, millions of panels could be sent into orbit, take advantage of the lack of atmosphere (which in turn will yield higher efficiencies), and beam this energy down to a receiver on Earth. Furthermore, panels in space could even shade the Earth, reducing the effects of global warming. 

Moreover, the ability to wirelessly transmit power from space to Earth could have significant implications for renewable energy generation. While the practicality of this approach is still a matter of debate, it's worth considering the potential benefits. For instance, space-based solar panels could generate power continuously without being affected by the day-night cycle or weather conditions on Earth. This could provide a more consistent and reliable source of renewable energy than terrestrial solar or wind farms.

Now, all of this sounds like a good idea until the cold hard facts of reality come slamming into the ground.

While it's true that energy has been wirelessly transmitted in space before, primarily through radio and microwave communications, the context of this research is unique. The researchers have demonstrated the transmission of power generated from solar panels in space to a receiver, a significant step towards harnessing space-based solar power. This is not merely about transmitting any form of energy; it's about transmitting usable power, which could potentially be directed to Earth.

However, it's also important to acknowledge the challenges and limitations of this technology. The high cost of launching and maintaining space-based infrastructure, the technical difficulties of transmitting power wirelessly over long distances, and the potential environmental impacts are all significant hurdles that need to be overcome. Furthermore, the efficiency of space-based solar power is still uncertain, and more research is needed to determine whether it can compete with other forms of renewable energy in terms of cost and performance.

Secondly, the researchers mention how they were able to receive this energy from Earth, and again, while this is true, this is no different to spaced-based systems communicating with equipment on the ground. Radio systems that have existed since the first satellite was launched into orbit convert electrical energy into radio energy, beam this energy down to the ground, and a sensitive receiver converts the radio energy into an electrical signal that can then be amplified.

The demonstration using LEDs does highlight one of the significant challenges of wireless energy transmission - energy loss over distance. Indeed, to receive a substantial amount of power on Earth, large receiving stations would be required, and space-based solar farms would need to be significantly larger than their terrestrial counterparts. However, it's important to remember that this is a nascent technology. As research progresses and technology advances, solutions to these challenges may emerge. For instance, improvements in energy transmission efficiency or the development of more effective energy harvesting technologies could make space-based power stations more feasible.

What alternatives would be better?

If the idea behind space-based solar panels is to try and encourage renewable energies, then it would be far cheaper and quicker to purchase vast amounts of land and build solar farms. In fact, it would make more sense to just outright purchase the deserts of Saudi Arabia, install the world’s biggest power cable, and connect nations across the planet to the world’s largest solar farm. Even then, issues with power reliability would persist as the sun is only around for 12 hours during the day (thus requiring energy storage).

While the idea of space-based solar power is certainly exciting, it's crucial to approach it with a healthy dose of skepticism. As with all scientific advancements, the true potential of this technology will only be revealed as it is further developed and tested. In the meantime, it's important to continue exploring other forms of renewable energy and working towards a sustainable future.

Constructing power stations in space would be excellent for space-based infrastructure, something that satellites and space stations already do. For example, it is likely that in the coming years, future missions to the Moon and Mars will need orbiting platforms to help with cargo storage and trips from Earth. Such a system will likely be vastly larger than the ISS, and therefore, power will be critical. 

But should wireless power from orbit become essential (not that it ever would), laser technologies might be far better simply due to the lack of beam divergence. Microwaves over short distances can be beam-like, but when transmitted from space to Earth, they quickly spread across large areas. A laser, instead, would be much more focused, significantly reducing the size of the receiver. However, a more confined beam is also far more dangerous, especially when using infrared and visible light, as the energy density is far greater. Furthermore, the atmosphere can interfere with the strength of the laser beam by the time it reaches the Earth’s surface, reducing efficiency. 

The experiment conducted by Caltech is a significant step in exploring the potential of space-based power generation. While the media may have sensationalized the discovery, it's crucial to recognize the value of this research in advancing our understanding of wireless power transmission in space. While it's true that terrestrial renewable energy sources like wind farms and solar panels are currently more feasible and cost-effective, space-based solar power could complement these sources and contribute to a more diverse and resilient energy mix in the future."

In conclusion

While the recent research from Caltech may not be as groundbreaking as some media outlets have suggested, it represents an important step forward in the field of wireless power transmission. The potential benefits of this technology, both for space exploration and renewable energy generation, are significant. However, it's also crucial to acknowledge the challenges and limitations and to approach these developments with a clear understanding of the realities involved. As the research progresses, I look forward to seeing how this technology evolves and what impact it will have on our future.

Looking ahead, the implications of this research extend beyond the immediate goal of wireless power transmission in space. The technology demonstrated by the Caltech team could pave the way for more advanced space-based power systems, potentially powering future space missions or even space colonies. Furthermore, the ability to wirelessly transmit power could have applications here on Earth, such as providing power to remote or inaccessible areas.

However, let's not get carried away. While these possibilities sound exciting, they are, at this point, nothing more than speculation. The reality is that there are many technical and economic challenges that need to be overcome before any of this can become feasible. The hype surrounding this experiment has, in my opinion, overshadowed this fact.

The Caltech team's demonstration of wireless power transmission in space is indeed a small step in a long journey, but it's a step in the right direction. It's too early to predict where this journey will lead us, but the potential benefits of this technology for space exploration and renewable energy generation are significant. As with all scientific advancements, the true potential of this technology will only be revealed as it is further developed and tested. While we should approach these developments with a clear understanding of the realities involved, we should also recognize the potential of this technology to contribute to our ongoing efforts to transition to renewable energy. Let's not lose sight of the bigger picture - every step forward, no matter how small, brings us closer to a more sustainable future.


By Robin Mitchell

Robin Mitchell is an electronic engineer who has been involved in electronics since the age of 13. After completing a BEng at the University of Warwick, Robin moved into the field of online content creation, developing articles, news pieces, and projects aimed at professionals and makers alike. Currently, Robin runs a small electronics business, MitchElectronics, which produces educational kits and resources.