The future of clean energy is waiting for us in space. Up there, above the atmosphere, the shining Sun is illuminating our planet with unfettered light. If only we could harness it.

Now, thanks to several technological convergences, we stand on the cusp of being able to do so, with plans for fledgling Dyson swarms of satellites that will collect sunlight, convert it into either microwaves or optical laser light, and beam that energy where we need it, whether that be down to Earth, the Moon, or other spacecraft.

A Dyson swarm, which you may have heard referred to as a Dyson ‘sphere’ — although that evokes images of a solid structure that in truth would be unstable and unworkable — has its roots in Olaf Stapledon’s 1937 novel Star Maker. Stapledon envisioned planetary systems surrounded by “a gauze of light traps” that collected solar energy. Stapledon’s imagination inspired Freeman Dyson to write a more technical treatise on the concept in 1960, and since then the concept of the Dyson swarm has become part of the fabric of SETI and the lexicon of futurists.

In principle, a Dyson swarm isn’t particularly complex. The sheer unfathomable scale of it aside, it’s just a bunch of satellites with station keeping, loaded with solar panels and a means of beaming that energy to its preferred destination. While we can’t build a Dyson swarm (yet), the ability to launch fleets of satellites to form constellations in Earth orbit is not only feasible but is being improved on.

Progress has been especially rapid in the past few years. “Even just 15 years ago people thought this was pure fantasy,” says Stephen Sweeney, who is a Professor of Photonics at the University of Glasgow, in an interview with Supercluster.

It’s all starting to come together because of the convergence of several disparate technologies and the pressure to come up with solutions to the climate emergency that is accelerating all around us. The three hottest days in recorded human history were all in the past two weeks.

One key factor has been the emergence of the private sector as a major player in spaceflight, having reached LEO en masse, reducing launch costs and increasing accessibility to space. SpaceX has launched over 4800 Starlink satellites to date.

Another is the development of ever more sophisticated semi-conductor technology required for crafting reliable, durable, and highly efficient solar panels. The final and most crucial factor made its first baby steps earlier this year.

On January 3rd, 2023, Caltech’s Space Solar Power Demonstrator (SSPD) roared into orbit on board a SpaceX Falcon 9. Among the three experiments it carries is MAPLE, the Microwave Array for Power-transfer Low-orbit Experiment, which is a prototype that future historians may one day look back on as the seed for a Dyson swarm.

That’s because MAPLE is able to convert solar energy into microwaves and then transmit those microwaves to a receiver that turns it back into electrical power. Sounds simple enough, but where MAPLE really made history was by beaming this microwave energy back down to Earth, where it was received on the rooftop of Caltech’s Gordon and Betty Moore Laboratory in Pasadena, California. It was only a small amount of power, mere milliwatts, but a startling demonstration of a concept first envisioned by Nikola Tesla.

Tesla wanted to eschew telegraph wires and find a way to transmit power through thin air. However, at the turn of the 20th century when he was conducting his experiments, radio technology was far too primitive for his ambitions. Today, of course, radio and microwaves beam power wirelessly all the time – whenever we take a call on our mobile phone or switch to Wi-Fi, or bounce communications off satellites, but in these, the transmission of information is the primary objective, and the power accompanying that information is rather low.

It’s one thing for MAPLE to transmit a few milliwatts to the ground, but if solar farms in orbit are to eventually replace fossil-fuel-burning power stations on Earth, the amount of energy they produce needs to get into the gigawatt levels.

Stephen Sweeney, who has been working in the area of wireless power beaming since 2009, sees the main obstacle to progress as the difficulty of scaling this technology. A single solar panel in space, with access to sunlight and no clouds in the way (unlike solar farms on Earth,) will receive a little over a kilowatt of energy per square meter. Current solar panel technology typically has a conversion efficiency of about 30 percent (higher efficiencies are being tested in lab experiments), so it might actually only generate between 300 and 400 watts per square meter.

Scaling that up, “You need a colossal amount of panels to get up to the gigawatt level,” Sweeney tells Supercluster. Not only would huge satellite constellations be required, but microwave transfer in particular would need enormous receivers on the ground. “The receivers need to be huge, on the order of 10 square kilometers — you’d have to build an artificial island to house them.”

In June, the UK Government awarded funding of £4.3 million to various universities and technology companies to address some of these challenges. Among them, researchers at the University of Cambridge as well as a Welsh technology company, MicroLink Devices UK Ltd, will receive some of the funding to develop lightweight solar panels that can withstand radiation in the space environment.

Solar panels are made from semiconductor materials, but “Semiconductors sometimes don’t like space because cosmic rays can cause damage,” says Sweeney. However, he points out that new materials that are not only flexible but perhaps better able to resist radiation are being developed. “There’s a whole range of completely new materials called perovskites that are very promising and cheap to make solar panels from.”

This recent British funding, coupled with the success in the United States of MAPLE, are both signs that the field is accelerating rapidly.

“The whole field is becoming more energized,” says Sweeney. “Groups all over the world, in Japan, the US, and increasingly more European initiatives, have all been looking at the possibilities of wireless power.”

Back in 2009, Sweeney was working with Airbus studying wireless power transfer via lasers rather than microwaves. Although lasers are more expensive than microwave equipment, and a cloudy day is enough to hamper their use, lasers do have their advantages for power transfer. They produce a much narrower beam, allowing the transmitter to aim at smaller targets. These targets might be other satellites or spacecraft, or a location on the Moon. On Earth, small and mobile laser-energy receivers could be transported to war zones or disaster areas to provide power where there is none.

Most recently, Sweeney has teamed up with a start-up called Space Power, with an eye on space-to-space energy transfer.

“The next step for space-to-space transfer is to figure out how to supply additional power to satellites in eclipse, to give them a boost,” he says.

When in the Earth’s shadow, satellites are not receiving any sunlight, and their power levels dip. The idea is to target their solar panels with lasers to give them a power boost, but ordinary solar panels are not optimized for laser light. However, future satellites can be built with this facility in mind. Space Power is designing a generic, off-the-shelf ‘plug-and-play’ system that can accept laser power and which aerospace companies can add to the satellites that they build. This could reduce satellite wastage, leading to fewer satellites breaking down or de-orbiting, and ultimately help manage the amount of space debris.

“We are looking to increase small satellite operating efficiencies by a factor of between two and five times,” says Keval Dattani, who is Space Power’s Director.

Another company, EMROD, plans to take the idea of power beaming a step further. With offices on three continents, they have partnered with Airbus as well as the European Space Agency and have plans for wireless power grids both on Earth and in space. In particular, EMROD plans a Worldwide Energy Matrix, which would be a satellite constellation that relays energy wirelessly across low-Earth orbit and to and from Earth. The energy wouldn’t necessarily have to be generated in space; to avoid having to lay cables on the ocean floor, energy from offshore wind farms could be beamed into space, relayed by the Worldwide Energy Matrix or something similar, and then redistributed to where it is needed.

“I think that’s a good way of looking at it,” says Sweeney on the idea of an energy grid in space. “Having an effective way of capturing energy in space and delivering it somewhere, whether that be Earth, or the Moon, or other space vehicles, is key. Once you have that space-based power station, a lot of other stuff will naturally follow.”

And that ‘other stuff’ could be the space dreams of Wernher von Braun, Freeman Dyson, Gerard O’Neill, and a legion of other futurists who have depicted a significant human presence in space, with space stations, moonbases, asteroid mining, and regular spaceflight. “For us, this is a neat solution with long-term benefits, not least for lunar outposts and asteroid mining, but back here on Earth too,” says Dattani.

Perhaps, too, constellations of solar farms could be the first baby steps along the road to eventually constructing a Dyson swarm.

It’s not all positive. If Starlink, OneWeb, and other emerging constellations of communications satellites threaten ground-based astronomy, then constellations of solar farms covering the sky could kill it off entirely. Even if space-to-space power transfer makes space telescopes even more viable, that still leaves the billions of people on Earth without access to an unspoiled night sky.

There’s also the issue of security. We’ve seen during Russia’s invasion of Ukraine how energy supplies have been targeted, from the Zaporizhzhia nuclear power plant to the Nord Stream pipeline sabotage. A fleet of unprotected solar-power spacecraft would make an easy and vulnerable target for the anti-satellite weapons currently being developed and tested. One solution might be to make these orbiting solar farms modular, so even if some modules are destroyed, either deliberately or by accident, the other modules continue to operate.

Because of the security fears and the huge engineering challenge of constructing a space-based energy industry, it’s unlikely that solar farms in space will replace all ground-based energy production in the foreseeable future. Wind, wave, geothermal, and solar energy on Earth will all still be needed, while nuclear scientists live in the perpetual hope that clean fusion will be able to replace toxic fission in producing significant contributions to our energy grids by 2050. Coincidentally this is the same date that the UK Government is hoping that space-based solar power will be generating 10 gigawatts of energy to the national grid, which is about a quarter of the UK’s current peak electricity demand. Other countries are aiming for similar gains from investing in space-based solar power.

As our planet warms, the hope is that solar energy from space, coupled with renewables on Earth and the large-scale development of fusion reactors, will hasten the end of fossil fuels. As anthropocentric global warming breaks new records for temperatures seemingly every year now, ice caps shrink at an ever-alarming rate and delicately balanced habitats become increasingly uninhabitable, new solutions are desperately needed.

You should expect wireless energy transfer to be coming to a home near you soon. Ground-to-ground wireless transfer is racing ahead, with innovations on the horizon including the ability to charge your car by laser as you drive on the road, meaning smaller batteries and less battery wastage, and to charge your mobile phone from anywhere in a room via laser. Scientists are now working to develop this technique so that it doesn’t harm our eyes should we accidentally look at the laser. Point-to-point microwave energy transmission between relays on Earth is also being developed with safety cut-off features should someone unwittingly get caught in the beam.

Large-scale or small, it seems that the wireless energy revolution is here. If successful, not only could it make for a greener planet Earth, it could help bootstrap our way to an orbital economy, based on the Moon and beyond, and start to look to the stars.

Building a complete Dyson swarm is a long, long way off if it could ever happen — Freeman Dyson casually suggested getting the raw materials for it by dismantling Jupiter.

Considering that even reaching gigawatt levels of energy production is going to be a stretch, then the concept of a complete Dyson swarm remains far-fetched. However, solar farming in Earth orbit could do us the world of good.