Space-Based Solar Power for Energy Transmission

One of the silver linings in the current coronavirus pandemic that is making ESG-investing types particularly happy is the news that Mother Nature is finally getting a breather as the wheels of commerce grind to a halt. Greenhouse gas emissions are way down because no one is going anywhere and factories aren’t producing stuff. Of course, it’s just a blip. The U.S. Energy Information Administration (EIA) projects that world energy consumption will grow by nearly 50% between now and 2050. That means we’re going to need to tap even more renewable energy sources like wind and solar, as well as invest in things like advanced nuclear energy, to meet future demand. There are also moonshot technologies like fusion energy. And then there are even more futuristic technologies that could literally involve the moon: space-based solar power for energy transmission.

What is Space-Based Solar Power?

Last year, we wrote about how floating solar farms were an innovative way to add renewable energy capacity without eating into valuable real estate. That’s sort of the proposition behind space-based solar power – except you’re floating solar panel arrays in orbit around Earth and transmitting the energy to a receiver on the planet. Such a system, of course, could also provide power to spacecraft headed to Mars or lunar bases in the future. 

Graphic shows basics of how space-based solar microwave satellite works.
Even an MBA can understand how space-based solar works. Credit: Solaren

The idea has been around since 1941 when science fiction writer Isaac Asimov explored the concept in a short story called “Reason” in which a space station transmits solar energy to various planets using microwave beams. An aerospace engineer named Peter Glaser first described the technical details of a space-based solar-power system in 1968. NASA, among others, has funded a number of studies over the years. While there are variations on the theme, the main thrust is that a huge self-assembling satellite would be launched into space. It would sport various reflectors or even inflatable mirrors to direct solar radiation onto solar panels. The energy is converted into either microwaves or a laser, which is then beamed to a power-receiving station of some kind.

Microwave Versus Laser-Transmitting Satellites

Let’s briefly talk about the two main types of energy transmission technologies being developed for sending solar energy from space back to Earth – microwave versus laser. This helpful graphic (and the other info in this section) from the U.S. Department of Energy (DOE) sums it up pretty well:

Pros and cons of laser solar satellites versus microwave solar satellites.
Credit: DOE

A few things to note. Microwave-transmitting satellites would need to be put into a geostationary Earth orbit (GEO), about 35,000 kilometers above the planet’s surface. Designs for these satellites call for solar reflectors spanning up to three kilometers, with the whole apparatus weighing as much as 80,000 metric tons or more. It would probably require dozens of launches to get all of the puzzle pieces together. If the idea of beaming microwave radiation directly to Earth sounds a bit disconcerting, not to worry: The big brains behind such concepts assure us that the intensity level is equal to the midday sun. 

In turn, one of the big concerns around laser-transmitting satellites is that they could be turned into some sort of superweapon. James Bond histrionics aside, self-assembling laser-based satellites would be a fraction of the size and could fit into one rocket. Though powerful enough to transmit energy to Earth at an extremely high efficiency (more than 50%), the size of the satellites means you would probably need a small fleet working together to make it worthwhile.

Advantages and Disadvantages of Space-Based Solar Power

On Earth, 30% of all incoming solar radiation never makes it to ground level. In space, no one can hear you scream – but the sun is always shining. That represents a potentially uninterruptible source of solar energy for at least five billion more years until the sun runs out of fuel. It’s also clean and green (if you forget about all of the emissions created by manufacturing and launching such a system). Just like global internet can provide connectivity anywhere on the planet, a space-based solar power system could send energy to remote locations. 

Graph shows energy demands by category through 2050.
Energy demands by 2050. Credit: EIA

You’re probably wondering just how much something like this might cost. That brings us to the major disadvantage, aside from the fact that while most of the technology is feasible, it isn’t yet deployable or operational at scale. The price tag is dependent on the type of technology proposed. A laser-based system could cost “as little” as $500 million, according to DOE. On the other hand, to build a microwave-based array at scale would be in the tens of billions. Thanks to SpaceX and the emergence of the NewSpace industry, launch costs have dropped dramatically in recent years. Still, based on the designs for massive microwave transmitting satellites (80,000 metric tons) at the bargain launch price of about $2,720 per kilogram (per SpaceX), it would cost $216 billion to power a major U.S. city. And that’s just the launch costs.

Current Efforts to Build Space-Based Solar Power Systems

Not surprisingly, there are only a handful of efforts to build space-based solar power systems. Last year, China announced plans to possibly 3D print space stations for catching solar rays and beaming them down to Earth, which would help defray the cost of launching massive satellites. Japan also has grand plans for an orbiting solar farm. About five years ago, Northrop Grumman (NOC) provided Caltech with up to $17.5 million to develop some of the technology needed to make such a system economically feasible, including ultralightweight components such as high-efficiency photovoltaics. More recently, the Air Force Research Laboratory awarded Northrop Grumman more than $100 million to build the hardware elements of the technology, with an eye toward powering remote military bases.

Startups Developing Space-Based Solar Power Systems

While big aerospace companies like Northrop Grumman appear to be leading the effort, there are a handful of startups that could play a role in launching a space-based solar power farm in the next decade. The list comes via SpaceFund, a venture firm that specializes in NewSpace.

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One of the leading companies appears to be an Australian startup, Melbourne-based Solar Space Technologies. The company’s co-founder, John Mankins, literally wrote the book on the subject, The Case for Solar Power. A former physicist at NASA, Mankins is one of the key figures credited with reviving U.S. efforts to build a solar farm in space. No word on funding, but it seems Solar Space Technologies is looking for government and commercial support from Australia, the United States, Japan, and elsewhere. The company says its solar power satellite, SPS – ALPHA, has been redesigned from previous iterations so that many of the components can be assembled in space instead of manufacturing one, expensive large system.

Solar Space Technologies illustration of solar microwave satellite system.
Credit: Solar Space Technologies
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Manhattan Beach, California-based Solaren is another startup proposing to build a space-based solar power (SSP) plant within the next decade. The roughly 20-year-old company claims it will send a megawatt-class SSP prototype plant into GEO as early as the mid-2020s. Solaren’s bigger ambition is to help power mining or space tourism operations on the moon. We have our suspicions about whether the timeline will hold based on past experience. Way back in 2009, Solaren entered into an agreement with one of California’s largest utility companies to provide competitively priced energy from space by 2016. It never happened.

Benefits of Solaren SSP system.
Credit: Solaren
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Founded in 2012, Xtraordinary Innovative Space Partnerships (XISP) out of Maryland is another company still in the proof-of-concept stage of what it calls Space‐to‐Space Power Beaming. Specifically, the company has proposed a detailed plan to use the International Space Station as a testbed for developing the necessary technology. It’s unclear where the mission stands. The most recent information from 2017 said the project was “proceeding under a combination of existing and pending NASA Space Act Agreement authority as well as evolving commercial, university, and non-governmental organization agreements.”

Startups Using Lasers for Energy Transmission

The other two startups on our list from SpaceFund are doing something quite different by employing ground-based lasers to transmit power to airborne platforms like satellites and drones. Let’s briefly dive into two startups using lasers for energy transmission.

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Founded in 2018, London-based Lumi Space raised an undisclosed pre-Seed round in January 2019. Rather than collecting solar energy from space and beaming it back to Earth, Lumi proposes to power satellites in space using lasers from Earth. The company’s value proposition is that electrical power systems can take up more than 25% of the cost, weight, and volume of a satellite. It proposes to reduce those costs by tracking satellites from the ground and shining lasers on them. Other applications include powering electric aircraft and removing space debris, according to Lumi.

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Founded in 2009, PowerLight Technologies out of Kent, Washington has raised a reported $2 million, according to the SpaceFund database. It is the only company on the list that is entirely working on planet Earth. It’s developing two types of technologies – free-space power beaming and power over fiber. Both rely on an optical technology that converts electricity into a high-intensity light (technical speak for a laser). It then shapes, directs, and beams this light to a specialized solar cell receiver that converts the light back to electricity. Applications? Free-space power beaming could help keep unmanned aerial vehicles such as drones in the air indefinitely. The latter could be used to help power tethered underwater robots.


The Kardashev scale describes a type-two civilization as one that captures the entire output of a star, perhaps using a megastructure such as a dyson sphere. That’s not happening anytime soon. Space-based solar power, and other technologies for energy transmission over long distances, is still largely in the experimental phase, so we wouldn’t expect it to even show up on the Gartner Hype Cycle any time soon. Heck, we’ve barely conquered wireless charging. However, retail investors need to pay attention to tomorrow’s technologies before they become yesterday’s news. 


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