The need for new, clean, renewable energy sources has never been greater. Global energy demand is forecast to double in the next 30 years, and governments around the world are struggling to come to terms with the Paris Climate Accords’ ambitious commitment of Net Zero by 2050 . This has all created the need for some very out of the box thinking, so far out of the box that it’s actually in space!

The UK government recently announced £4.3 million of government funding for universities and tech companies to help develop Space-Based Solar Power (SBSP). This follows hot on the heels of the news that scientists working on Caltech’s MAPLE experiment were able to successfully beam solar power to Earth from space for the first time. So is this technology really a feasible way to solve the Earth’s clean energy needs, or is it destined to remain the stuff of sci-fi?

The Technology

In space, the sun always shines. No clouds block the sun's rays and if the orbit is chosen correctly, you can even avoid the night. Using these conditions in space to create a source of energy on Earth perhaps surprisingly is not actually a new concept.

The 1970s saw extensive research into Space-Based Solar Power undertaken by NASA and the US Department of Energy. "There is no science to solve” as “we have it all worked out pretty much since the 1970s” says Ian Casha British engineer, whose CASSIOPeiA Solar Power Satellite concept has been adopted by a U.K. government-backed space energy initiative.

Turning science theory into commercial practice tough is the tricky part. The UK government seems to have faith though with a BEIS commissioned independent study concluding in 2021 that “it is technically feasible to develop a substantial Space-Based Solar Power capability for the UK, and to complete this well before 2050.”

What’s changed?

Essentially the concept of SBSP is straightforward, solar panels on satellites collect energy from the Sun and beam it safely back down to Earth with wireless technology. But whilst solar panels and satellites are already part of everyday life the safe wireless transfer power in large quantities from space to Earth certainly is not. This is why Caltech’s MAPLE experiment was so groundbreaking.

MAPLE, short for Microwave Array for Power-transfer Low-orbit Experiment, demonstrated in June its ability to wirelessly transmit power in space and to beam detectable power to Earth for the first time.

MAPLE successfully used constructive and destructive interference between an array of flexible lightweight microwave power transmitters in order to shift the focus and direction of the energy it beamed out without using any moving parts. This video from Caltech provides a demonstration of how this works.

For SBSP to be feasible, energy transmission arrays need to be flexible enough so that they are able to fold up into a package that can be transported in a rocket, and lightweight enough to minimize the amount of fuel needed to send them to space; keys factor in the commercial case for SBSP.

The process has also gone through major development in the last few years. Reusable rocket technology such as the new Falcon 9 from SpaceX has made space launches much more cost-effective. The company can now build, fly, and land its rockets multiple times, reducing the cost of each launch. In fact, thanks to SpaceX the cost per kg for space launches is approximately 10 times cheaper than it was a decade ago with this number set to fall even further with the arrival of the new SpaceX Starship currently in development.  So we are close to or even at the point that SBSP can start to look commercially viable.

Other technology has developed rapidly too. Remote space robotics have improved markedly and modular solid state solar power satellite designs such as SPS Alpha and CASSIOPeiA are designed for high volume commercial manufacture and so are far more affordable than previous concepts.

What are the Challenges?

If this technology can successfully be harnessed it would mean perfectly clean electricity, available 24/7, beamed at a steady rate without blackouts or sudden overloads to anywhere in the world without wires or power lines. The scale is certainly eye-opening too. A UK government backed study found that Space-Based Solar Power could generate up to 10GW capacity a year by 2050, a quarter of the UK’s current electricity demand by 2050.

As exciting as these recent technological breakthroughs are, some very practical challenges still exist.  The manufacture and assembly of large scale and high precision structures in space is far from straight forward, these would require large-scale robotic assembly and maintenance at a level not yet seen. And despite MAPLE’s breakthrough, we are still some way off being able to achieve the required wireless power transmission conversion efficiency to make SBSP functional.

But the biggest obstacle is still cost. The up-front development costs needed to bring the theoretical concept into a working energy system come with the type of long-term high-risk return of investment that few commercial investors are comfortable with. Then once the system is successfully up and running, establishing a levelised cost of electricity (LCOE) competitive with other renewables would be required to make SBSP commercially viable.

Then of course are there are the common issues with establishing a large structure in space such as the risk of micrometeorite damage, the contribution to light pollution and the creation of debris at end of life. This is in addition to the need to demonstrate beyond the shadow of doubt that highly focused powerful beams of energy from space pose no safety risk to the population on Earth and couldn’t ever be used as a weapon of mass destruction.

What’s to come?

The UK’s £4.3 million government funding for universities and tech companies to develop Space-Based Solar Power is intended to make the country a world leader in the race for this technology. But the UK is far from alone. The EU’s SOLARIS program had funding approved in November 2022 in order to establish the technical, political and programmatic viability of Space-Based Solar Power and prepare for a decision in 2025 on a full development programme.

Following on from Caltech’s success, the US Naval Research Laboratory launched a mission to the International Space Station earlier this year with the goal of beaming power across space using laser transmitters.

But the most ambitious plans come from Asia. Japan’s space administration JAXA first successfully demonstrated kW scale wireless power transmission back in 2015 and now has plans to attempt to beam solar energy from a series of small satellites in orbit from as early as 2025. China has a similar timescale for a space based solar farm and in turn hopes to generate megawatts of power by 2030 and a gigawatt levels before 2050. Definitely one in which to watch this space!

Written by Tom Wild and Lloyd James