Space-Based Solar Power: Folly Or Stroke Of Genius?

The Sun always shines in space, unless a pesky planet gets in the way. That’s more or less the essential thought behind space-based solar power (SBSP) as newly pitched by ESA’s director general, Josef Aschbacher on Twitter. Rather than putting photovoltatic solar panels on the Earth’s surface which has this annoying property of constantly rotating said panels away from the Sun during what is commonly referred to as ‘night’, the panels would be put stationary in space, unaffected by the Earth’s rotation and weather.

Although a simple idea, it necessitates the solving of a number of problems. The obvious first question is how to get these panels up in space, hundreds of kilometers from the Earth’s surface, to create a structure many times larger than the International Space Station. The next question is how to get the power back to Earth, followed by questions about safety, maintenance, transfer losses and the inevitable economics.

With organizations ranging from NASA to China’s Academy for Space Technology (CAST), to US institutions and others involved in SBSP projects, it would seem that these problems are at the very least deemed to be solvable. This raises the question of how ESA’s most recent proposal fits into this picture. Will Europe soon be powered from orbital solar panel arrays?

Asking The Right Questions

Simplified summary of space-based solar power (SBSP). Credit: ESA.
Simplified summary of space-based solar power (SBSP). Credit: ESA.

ESA’s announcement doesn’t come out of nowhere, but follows the completion of two studies on the topic that were commissioned at the beginning of this year. According to these studies it would be possible to provide competitively priced electricity to European homes and businesses by 2040, with as big selling that this could alleviate the need for large-scale grid utility storage solutions.

As we have covered previously, grid-level storage is going to be under pressure to bridge dips in solar electricity production. SBSP satellites would however be beaming energy down to Earth ideally 24/7, giving them similar performance to a nuclear power plant at well over 90% capacity factor. This is also noted on the ESA overview page for SBSP and specifically their proposed SOLARIS project.

In a nutshell, the lack of atmosphere makes space-based solar significantly more efficient than Earth-based solar, with a projected SBSP satellite requiring about 600,000 panels stretching over a kilometer across to generate about 2 GW, akin to a nuclear plant with two reactors.

For the ground-based receiving station – for the microwave or laser-based radiation being beamed down from the SBSP satellite – a footprint of about ten times that (~10 km) would be needed. Although this would make the ground-based footprint smaller than that of the roughly six million PV solar panels plus overcapacity, it would take significantly more space than a comparable coal, gas or nuclear power plant.

The questions here seem to condense down to two primary questions, assuming that fossil fuels are not an option:

  • Is SBSP competitive with a well-run nuclear power program as in e.g. South Korea and China?
  • Is SBSP competitive with a 100% renewable grid backed fully by storage?

A Political Minefield

It is an unfortunate reality that energy policy is heavily politicized. When it comes to ESA’s SOLARIS pitch, this could be regarded as a way to get funding approved for Europe’s own heavy-lift rocket program that could compete with something on the level of SpaceX’s Starship.

This is a point raised by Eric Berger in his analysis, which also references Elon Musk’s strong dismissal of SBSP, and a 2019 analysis by physicist Casey Handmer of SBSP.  Handmer addresses the other elephant in the room, of transmission efficiency and overall system losses. The power from the solar panels has to be converted to microwaves for transmission, transmitted to the ground station, which captures what makes it through the atmosphere using a gigantic metal mesh antenna, where it has to be converted again to a form usable for the electrical grid.

Artist impression of a solar power satellite. Credit: ESA.
Artist impression of a solar power satellite. Credit: ESA.

Assuming a generouss 80% conversion efficiency of the PV electricity to microwaves, this would also require the satellite to somehow deal with 400 MW of waste heat for a 2 GW array in an environment where heat shedding is notoriously difficult. For the microwave transmission itself through the Earth’s atmosphere, losses would be incurred as well through attenuation and reflection by water and other elements (Karmakar et al., 2010).

The power that would ultimately be received on the ground would thus be anything but constant, but rather fluctuate with factors like the amount of water vapor between the satellite and ground station antenna. Of the 2 GW originally captured, 1.8 GW would be converted to microwaves, which by the estimate of Dr. Handmer would be no more than 40%, leaving us with 720 MW, which after further ground station and transmission losses is likely to amount to between 500 MW – 700 MW, depending on the weather.

At this point we find ourselves confronted with the uncomfortable question about the logistics of getting these satellites into space, assembled, and above all funded.

Too Cheap To Measure

MMOD damage on ISS solar panel.
Damage observed to ISS solar array 3A, panel 58 (cell side on left, Kapton backside on right). Note by-pass
diode is disconnected due to MMOD impact. (Credit: Hyde et al., 2019)

As fast as launch prices have been dropping ever since companies like SpaceX threw down the commercial launch gauntlet, getting a kilogram of anything up into orbit is still expensive, even with SpaceX’s Starship flying regularly. Its launch cost would be likely about $10 million per flight, or $100 per kilogram. The weight of one of these satellites would be far more than the entire ISS, including its PV panels, supporting structure, microwave generator and transmission antenna plus additional control and communication hardware.

The cost of one of these satellites plus ground station would be in the order of billions, all to generate the equivalent of what a large concentrated solar plant (CSP) or small nuclear plant could generate today. Even assuming launch costs were to drop to the $10/kg suggested by Elon Musk, it would not fix the thermal issues and transmission losses. Nor would it address the unsolved problem of assembly and maintenance.

If the ISS were launched today with a Starship, it’d still need in-orbit assembly using humans and/or a robotic arm. Assembling the largest in-orbit structure in human history presents many open questions. The ESA-commissioned Frazer-Nash report states that they expect in-orbit assembly to take anywhere between four to six years, per satellite.

Even assuming that optimistic estimate, this compares to the five to six years construction time observed (Lovering et al., 2016) with nuclear plants, e.g. during France’s 1970s build-out or today’s nuclear power plant construction in China, with even the massively delayed and over budget Olkiluoto 3 EPR reactor at about €8.5 billion for 1.6 GW output reaching an levelized cost of electricity of €30/MWh. Modern reactors also have a rated lifespan of 80+ years, which further helps to amortize the large up-front costs.

This leads to the next point, namely that of maintenance. Although SBSP satellites and PV solar arrays are safely outside the bounds of Earth’s atmosphere and its weather, they are subject to space weather, including space debris, as well as micrometeorites. The ISS has seen its share of damage to both its central structures and its solar panels. Together with the increased radiation exposure in space, this means that space solar arrays would degrade much more rapidly than ground-based arrays, and possibly be taken out by an unlucky hit on a crucial part of the satellite.

The expected lifespan of such a satellite can be estimated based on data gleaned from the ISS in particular. Unlike Earth-based solar arrays, the arrays on spacecraft use gallium-arsenide instead of silicon. These do not degrade as quickly in the harsh environment of space, even if they’re still vulnerable to a kinetic strike. This necessity to radiation-proof the PV solar panels also means that they’re much more costly than the mass-produced PV solar panels commonly used on Earth.

With in-orbit repair for these SBSP satellites, here too we run into the problem that no such thing has ever been attempted, beyond maintenance work on space stations like the ISS, using astronauts and robotic arms, and the service missions on the Hubble Space Telescope. These were heroic endeavors.

A Hard Case

As a potentially much cheaper alternative to SBSP, one can imagine something like space-based mirrors. These would not be as high-tech as orbital PV solar arrays beaming microwaves to the ground, but could be as simple as self-unfolding mirror satellites with ion thrusters to maintain position. These could reflect sunlight to a PV solar array on Earth, for example, costing only a fraction and using mostly proven technology.

Back in 2019, China had announced that it would ‘most likely’ launch its own SBSP satellites into orbit between 2021 and 2025, with a MW-level satellite being launched by 2030. So far there has been a severe lack of updates. The distinct feeling here is that perhaps SBSP is more of a national prestige thing, even more so than space stations. From massive orbital construction to a range of other ‘never done before’ items, a successful SBSP project would perhaps be the grandest national power flex imaginable.

Meanwhile it seems that the best strategy to power our societies is to keep building nuclear plants alongside solar and wind, none of which requires us to invent whole new technologies and industries from scratch.

137 thoughts on “Space-Based Solar Power: Folly Or Stroke Of Genius?

    1. If we are to put something at L1, we should consider solar wind direct electric conversion instead of photovoltaics. Much more efficient, magnitudes less costly, could last generations, less prone to failure and deploying a “shading system behind it would also be possible.

  1. well. keep on dreaming and please let the androids in charge of said station not get religion (Asimov’s Reason) but a few things pop in my head immediately:
    1. what is the power received per square meter in space.
    2. how big does the setup need to be.
    3. where to park it? Lagrandes are notorious difficult to maintain, especially at this scale.
    4. how to service it?

    and that covers not even the transport side.

    Brr. I rather keep reading those old scifi books…

        1. There is the L5 Song by Higgins and Gehm, which can be found in The NESFA Hymnal (volume 1). It anticipates (in 1978 already) the problems of power transmission from space.

          Here it is, with attribution:

          Home on Lagrange (The L5 Song)

          by Bill Higgins and Barry Gehm

          Copyright 1978 by William S. Higgins and Barry D. Gehm
          (Sung to the tune of “Home on the Range”)

          Oh, give me a locus
          Where the gravitons focus
          Where the three-body problem is solved
          Where the microwaves play down at three degrees K
          And the cold virus never evolved

          Home, home on Lagrange
          Where the space debris always collects
          We possess, so it seems,
          Two of our greatest dreams:
          Solar power and zero-gee sex!

          We eat algae pie, and our vacuum is high
          Our ball bearings are perfectly round
          Our horizons are curved, and our warheads are MIRVed
          And a kilogram weighs half a pound

          You don’t need no oil, nor a tokamak coil
          Solar stations provide Earth with juice
          Power beams are sublime, so nobody will mind
          If we cook an occasional goose

          (Interlude, sung to the tune of “Oh, What a Beautiful Morning”)
          All the cattle are standing like statues
          All the cattle are standing like statues
          They smell of roast beef every time I ride by
          And the hawks and the falcons are dropping like flies…

          I’ve been feeling quite blue since the crystals I grew
          Became too big to fit through the door
          But from slices I’ve sold, Hewlett-Packard, I’m told,
          Made a chip that was seven-foot-four

          When we run out of space for our burgeoning race
          No more Lebensraum left for the Mensch
          When we’re ready to start, we can take Mars apart
          If we just find a big enough wrench

          I’m sick of this place, it’s just McDonald’s in space
          And living up here is a bore
          Tell the shiggies don’t cry, they can kiss me goodbye
          Cause I’m moving next week to L-four!

    1. The solar energy in space at Earth’s orbit is about 3 times greater than at the surface. They need to be a geosynchronous orbit (20,000 miles) to feed a fixed receiver. Focus can be very good with coherent microwaves. It can be built so that if it wander of the antenna it looses coherence and becomes harmless. They could also use reflectors for heat and a turbine that runs on some convenient gas/liquid cycle. Like ammonia.

      But really, nuclear. Maybe this thorium cycle that looks so good. If not, there are vast amounts of uranium. Choosing the China as an exemplar is pretty goofy considering no data can be believed. And no mention of France? Nuclear, with wind/solar for very remote areas and get rid of this windmill blight on the finest vistas on land and sea.

    2. These projects are just government money sink holes.
      ESA is in pretty dire situation, having missed the whole reusable launcher, they have lost all commercial market possibilities outside subsidized launches.
      They have a bad hammer, so they are searching for any possible nails, even their own finger ones.

    3. What about heating up the planet? All that extra energy from the sun will cause the earth to heat up even faster. Think about it. Those extra rays of sun were not going to hit the earth. But now you’re going to collect them and send their energy our way. Not a good idea.

  2. What happens when you turn up the heat to a simmering pot of water ?

    Redirecting more (solar) energy towards a planet that is already starting to suffer from global warming in my mind is fundamentally a bad idea. If you add 720 MW of power that will all eventually end up as thermal energy.

    Although all that extra energy will eventually cause more water in the sea to evaporate into the atmosphere, which may counteract increasing sea levels from the melting ice at the poles. But on the flip side a denser global atmosphere may mean that hurricanes and typhoons would have greater kinetic energy. And also on the flip side yet again, all that extra water vapour in the atmosphere, will end up forming more cloud cover which will reflect some direct sunlight back into space.

    1. The big point with energy that has to be remembered is the Earth isn’t just capturing solar energy, its also radiating energy back into space and as long as the ratio of incoming to outgoing is reasonably close to 1:1 the surface/atmosphere of the Earth and our precious Biome remains stable enough. Doesn’t matter if the added energy comes from underground or outerspace – effectively its all solar power via varying degrees of directness anyway! It is the adding of energy faster than it can radiate away that is the problem.

      Where the energy comes from can have other effects – like all those lovely green house gasses, or in this case perhaps causing serious harm to the stuff living in and around the downlink beam, but ultimately our energy consumption needs would be met somehow, adding ‘heat’ to your metaphorical pot only if the waste heat can’t radiate away… Which in theory is a problem this concept could solve, as long as we don’t just increase our demands and keep pumping more greenhouse gasses.

      1. I do however think this idea is pretty terrible, a high power concentrated beam likely to damage life seems like a very bad idea, and we need to invent more magic to make it efficient enough to be worth it I would think.

        1. They can be built so that if they wander off the antenna they loose coherence. Also the big studies back in the 197o’s shows that the land under the antennas can be safely farmed. To the heat flow issue I guess the primary point is that there is no CO2. Despite the excess energy that would not have hit the Earth, CO2 levels should go down and the Earth to cool.

          1. I’d certainly not want to be inside the horizon of one those things, let along farming in the path… Its a pretty substantial boost to the bombardment you would get ‘normally’ even in this rather unnatural world, ‘safely farmed’ can mean anything from crops won’t be ignited, through no obvious effects in 2 weeks, to you can sunbathe in the beam and take no further harm than under the sun too long… Which is no doubt very dependent on just how powerful and narrow the beam is.

            ‘loose coherence’ will always be an in theory, and should – sure we are getting good at making reliable space hardware, but part of that is that there is no great gains and so reason for anybody to want to weaponize the stuff out there – even the ISS huge as is it deliberately crashed on something would not really achieve anything much, and we are at least supposed to believe nobody has lofted anything that would be all that much deadlier on return.

            But something like this could really be a death ray…

        2. It’s not a high power beam. In fact it’s a very low power bean… less than standing under the light of the full moon. And collected using the same material to block microwaves from escaping or current ovens.

          1. If its that low power it needs to cover stupidly vast areas to actually make meaningful contributions, so you are almost certainly way way way (add in as many more as can be bothered to convey the shear order of magnitude) better off with ground solar in place of the ground station… For such things to really have any chance of making sense its got to be a rather powerful beam, and more specifically all power transmitted in a very narrow band as well so the receivers can be well tuned to collect it efficiently – moonlight is a pretty full spectrum so not a good comparison – its more like would you stick your head in the microwave? Even a low power one would be a bad idea as the whole damn point of microwaves is they are in that tiny frequency range that is really strongly absorbed by water, and your head is full of water and water adjacent stuff…

            And just because its supposed to rather dispersed doesn’t mean it will be, if the total output is supposed to be in the mega or even giga watt there is a huge energy transfer that is only ‘safe’ because it is as widely dispersed on the ground as it is supposed to be, little error/sabotage here and there and you have the death ray potential starting to creep in…

        3. There is a fool-proof test to determine if any “green” energy proposal has true merit: simply announce your intention to build it next door to where a wealthy “climate change” activist lives. The test is most decisive when the test subject is a multi-millionaire and/or a politician.

          Doubt it? Look up the Cape Wind Project.

          D’you suppose Al Gore or Bill Gates want a solar microwave power receiving station built anywhere near THEIR home?

          Speaking of homes… If the world will end in 12 years due to climate change and a deluge of melted polar ice cap water… why do the super rich continue to buy prime beach-front real-estate and even their own islands?

          Perhaps people at that socioeconomic level have access to better information sources than CNN?

    2. You are so brutally astronomically mistaken if you think that even many hundreds of gigawatts would have any efect. Earth receives continuosly more than hundred petawatts of energy from Sun.

        1. It’s not even the energy use that’s causing climate change, it’s the greenhouse gasses trapping the heat. Since this wouldn’t generate ongoing greenhouse gasses it would be a net decrease in heat if we convert to it.

        2. A common misconception.

          The earth receives about 173,000 terawatts of energy from the sun -and- therefore also reflects and radiates that same amount back into space. (The amounts of energy must balance, on average) for temperature to stay the same or to change slowly.

          The reason climate change works is because CO2 (and other substances) in the atmosphere absorb and reflect some of that 173,000 TW.

          The total amount of energy flowing is so great that a small proportional change can still involve shocking quantities.

          Look into gray body radiation if you need more detail in understanding how that’s possible.

      1. It’s enough solar energy to power multiple Katrina sized hurricanes every second. That one hurricane unleashed more energy than the whole human race uses in more than a decade.

    3. the comparison as it looks today is (unfortunately) how many GW we get from orbiting solar vs how many we get from fossil fuels. they both add energy in addition to the current solar budget, but the carbon fuel sticks around after it’s burnt too.

      of course, by the time it is technologically feasible, it will be competing with other energy sources and a different energy demand. it might well be that at that time it looks worse.

    4. This is missing few references. First, the PV array has a efficiency lower than 1. So instead of a flux of 3.6kW/m2 you’d get without the panel, you now have 0W/m2 behind the panel (ok, probably a bit more, in the infrared band, since the panel will radiate waste heat). If the panel is in front of the Earth, that means that you’ve actually reduced the amount of irradiation received by the Earth.

      Then you beam that reduced power to the Earth with a very bad efficiency (let’s say you are actually sending the equivalent of 0.7kW/m2). This will not increase the Earth thermal input, instead, it’ll decrease it considerably, instead of 3.6kW/m2 (but hard to capture), you now have 0.7kW/m2 (easy to use).

      Now, let’s make a parallel to the energy received by the Earth each second: 173’000 TW. So even 2GW missing is only 11e-9 part of the received value.
      The Earth’s albedo is 31% (already integrated in the number above), so tapping this energy with a PV means lowering the albedo (less is reflected to space), so it’ll actually increase the temperature of the Earth. But again, the scale factor here is so large that to have any measurable effect, it would require changing areas that are hundred of kilometers wide.

      Don’t also forget that any energy “produced” on Earth ends in thermal energy / heat, so it’s not extracted, just temporary used before it’s emitted back to space.

      Said differently, such system is just non sense compared to plain old oriented orbital mirrors that would be use to focus light to receiving PV stations. Even with a mirror with 99.99% reflectivity (they do exists), you’d loose a large part of the flux in the atmosphere (around 25%), so in the end, at best you could tap 75% of the solar energy, multiply this by the efficiency of your panels, ~40% for the record rate of PV, IIRC), that’s only 30% of the initial available power. I’m not accounting for concentrated solar which gives even higher efficiency and that would exactly fit this scheme.

      With their computations, they expect to capture 500MW out of 2GW, so only 25% efficient, with all the hidden costs, hard to believe it can breakeven.

      But an array of orbital mirrors could also be used to shade large part of the Earth and help control the weather and this is another benefit (although in the former case, the best position for the mirrors are L4/L5 points so they are always facing the sun and the Earth, but not the same place on Earth), and in the latter case, they should be geostationary to always shade the same place on Earth, like a desert, or the north pole.

      1. Since Earth rotates, any geostationary object would have only a very brief shading effect on Earth, i.e. around noon. Consider the durations of solar eclipses. In addition, if you consider the relatively small span of such an object, e.g in comparison to the Moon, the shading effect of the roughly collimated sunbeam would be miniscule.

    5. No. The earth radiates energy away at a truly astonishing rate. On average, it radiates exactly the amount of energy into space that it receives from the sun.

      Increasing the energy input to the earth by a percent of a percent of a percent isn’t going to make an appreciable difference.

      That’s also why the greenhouse effect is pernicious. It interferes with the earth radiating energy into space (important IR wavelengths are reabsorbed by the atmosphere or reflected by it), so it’s interacting with a truly incredible amount of energy already.

  3. But wasn’t this all part of a package described by Gerard O’Neil? Mine the asteroids, build space colonies, and ample power for everyone. The only problem was the microwaves from space. And maybe a few other minor things that had to be solved.

    CoEvolution Quarterly covered it, then issued a book in magazine format. O’Neilhad “The High Frontier”, in hardcover and paperback, I think from Bantam Boojs. Back when pocket paperbacks were the cheap way to distribute information.

    1. Yeah how many gigawatts of microwave energy in a focused beam is falling straight down above me? And what’s the safety interlock if the tracking fails? Even if it’s foolproof, it’s gonna be a hard sell. Chernobyl is looking pretty verdant just a few decades later, Fukushima was a total nothingburger, yet even rehabilitating that PR is proving impossible. Plus the sad issue of how do we create our fertilizer via the Haber process if we stop burnin’ that oil?

      I think the utopianism of the 1950s-70s faded out for a reason. Sad, but exuberance sometimes has consequences.

      1. What happens to all the insects and birds flying through the beams too? Will it essentially be a bunch of irradiated death zones in the air that eventually whittle away all our pollinators and migratory flying animals? It’s a pain but all these solutions look good at first the same way fossil fuels did; the realization of the hideous second-order effects comes decades or centuries later. Or maybe millennia, we don’t know yet.

        1. Why does it have to be a frequency that interacts with living things? If anything, we would want to use a frequency that doesn’t interact with water (which is how microwave ovens heat food) because of these things called clouds.

    2. Yes, it was (I used his GR book as the main text for a class). And a number of other studies and gatherings worked out most of the details 40 years ago. One is that the coherence has to be maintained by feedback. Loss of coherence produces a huge broad beam that is harmless. You can imaging the foot print from a flat plate with thousands or millions of little transmitters if the beam forming fails. They are 20,000 miles away. Of course you can figure it would just shut down, but in the case of terrorist threat, they could not point it anywhere without the phase feedback system and how it is encoded. I picture beam forming antennas like the Starlink flat plate. Just much much bigger.

    3. I came to the comments for this. There’s been a lot of chatter in the news about this topic and it seems most sources are completely failing to mention Gerard K. O’Neil’s work. Anyone interested in space based solar power NEEDS to read The High Frontier and the associated portions of the NASA study he worked on (NASA SP-413 Space Settlements: A Design Study). He and his team had already completed many of the necessary calculations back in 1974 (the same ones you see people speculating about in the comments sections of articles just like this). Sure, the situation today is different and calculations would need updating to accommodate for current economic/environmental conditions, but the major conceptual work is already done.

      1. I have High Frontier, NASA SP-428, and other documents in front of me. I knew Dr O’Neill and the work at Princeton and MIT. It’s good that this stuff is back on the table. It’s bad that we had to wait over 40 years for this stuff to be “reinvented” … without attribution.

        1. Yes, the lack of Attribution is very troubling as well as the re-thinking of everything as if new. I knew Robert Forward and discussed his and O’Neil’s “big picture” concepts several times. Maybe it is a modern Tik-Tok science effect. Nobody reads anything older than a few months or beyond the top 3 hits on Google?

  4. The ground receiver for Europe would probably be in the Sahara, making Europe dependent on the religio-political conditions there.
    As for China, if their shaky economy could even make the space station happen, it would be seen by many as a space based weapon.

    1. It is another weapon in disguise, worse than atomic bombs. Whoever is in control of such a system can roast anything on earth. There is no country or other entity on this planet trustworthy enough to operate it.

      1. That isn’t how it works. The beam forming needs a feedback system to maintain coherence. The transmitter is 20,000 miles away.

        But you can start a new version of “The China Syndrome” and scare people into opposing it.

        1. It’s still a threat even when defocused. Less than 100W/m² for a prolonged period would be enough for substantial indirect damage from melting glaciers and permafrost soil.

    2. I think you’re right. Besides the political issues, I have a few concerns that weren’t around when I heard about this in Junior high…I like the idea. But a lot has happened since then and I am (hopefully) wiser now.

      “Global” does not necessarily equate to “robust” as anyone who has bought or sold anything in the last three years has witnessed. You’d think we’d have learned that consequences pile up as the scope of the project increases.

      Assuming reliability could be established at a design level, the minute the contracts were announced every black hat on six continents would be trying to get onto the project. Think we have issues with ransomware now? Wow. Not to mention operatives from the FSB, North Koreans or any other shady government entity with an acronym for a name.

      What about terrorists? Every idiot with a cause would be trying to create a Kessel event or, if the satellites were in high orbit, to take over the software remotely or hijack a space tug to use as a kinetic weapon. On the offensive side, the array in Edward Lerner’s novel, Energized, used steerable microwave arrays to compensate for atmospheric distortion that also made a nasty 500 MW death ray in the wrong hands.

  5. Launch batteries into space, charge them there and bring them back down. It’s crazy but if you could somehow use the solar energy to power the rockets then it could be self sustaining. We are talking about enormous amounts of energy of course, but it is there for the taking. Unlike humans, the batteries are in no hurry, so that opens up more possibilities for transporting them.

    Maybe I’ve read too many science fiction novels but that energy beam would be the ultimate terrorist weapon.

    1. Ah hahaha! Fantastic. That is exactly how Swift Enterprises is financed in the Tom Swift Jr. books. The first one is about his rocket ship and using it to charge their special batteries. Or was it is outpost in space. If you want a world with alternate physics, give them a shot.

  6. I think the only way it can remotely make sense is with thin film solar on a rotating satellite. Any traditional panel is just too heavy to put into space. If the solar panels are just a km long strip of mylar with thin film PV, you can cover a lot more area with a lot less weight.

    The major hurdle is whether charged particles can be kept from the active layer with a relatively thin cover layer. Maybe some wire electrodes creating an electrostatic field in front of the strip could help?

    1. His launch costs are $20k/kg and he says it’s estimated that it would have to come down to $100-$200/kg for it to be viable – which is where the article above says we’ve now reached.

      However, it still feels like a HUGE use of resources to put a very complicated and expensive (and still intermittent) system in place compared to just carpeting a few bits of barren desert with regular cheap (and getting ever cheaper) solar panels and running a very long wire to where it’s needed – sure that’s still a challenge but it feels a lot more doable and a lot easier to maintain, the UK are having a go at this exact thing with Morocco:

      Couple this up with some storage (which is also getting cheaper all the time) and I think wind & solar are just going to keep on making all these sci-fi moon-shot style alternatives obsolete before they’re even off the drawing board.

  7. Throwing money and precious resources at this pipe dream is criminally irresponsible – especially when we could be spending far less money on thorium salt reactors for a far faster and more certain ROI.

    Let’s forget for the moment the huge-and-likely-insurmountable obstacles mentioned by Maya Posch. Let’s instead look at the challenge of simply keeping the thing working! There are meteorites, space junk, possible destruction by enemy countries, and the simple electrical mechanical and electrical failures that everyone reading this is all-too-familiar with. Assuming for the moment that this white elephant is ever built, how ruinously expensive will major repairs be?

    We have far cheaper, more certain, and more reliable technologies than SBSP to pursue in our attempts to curb AGW.

    1. Let space power, power space machines . IMHO. I agree, reactors is what we need. A nice reliable energy source. The so called global warming (or to the next generation, it could be global cooling, or maybe something else by then to stir the pot for $$$) need not be part of the equation. Just good solid reliable energy for all.

    2. Don’t be uni-dimensional when analyzing such projects. It’s not “one and done” kind of thing, there are several independent factors that surely can be reused on another project:
      – sending things to space
      – robotic maintenance
      – wireless power transfer
      – autonomous impact detection and avoidance
      – lightweight materials

      A lot of the “parts” of the project surely can be used somewhere else, and the companies doing the parts will profit from patents and know-how later on. The amount of money spent on this project will surely advance several fields that currently don’t have the funding nor the incentives to be studied.

      A multi-billion dollar (or euro) project is a good incentive.

    1. Everyone seems to be concerned about the beams aimed at Earth. I think it far more likely and more attainable that in the event of a conflict the SBSP beams would be directed onto other countries satellites, whether at LEO or Geo orbits.

    1. Think of how the internet started out as a nice idea to share information for all…. Then along comes people who write viruses, take over machines, ransomware, and we are a constant feedback loop now to keep bad actors at bay …. Oh, yeah, Space beams would never be misused…

        1. Actually it was … Sure the seed was planted with ARPA, then NSFNet, but it wasn’t until 1989-1990 (Wiki) that the WWW was born by linking hypertext documents accessible from any node on the network. The idea was ‘information’ sharing which we know was a ‘big’ leap. No need for ‘secure’ http, ftp, etc. Just simple gopher, http, ftp, tftp, and use clear text tcp/ip connections between machines …. Ie. Useful tools to share information and secure if necessary only (say banking, military) . Life was great…. But then we know what happened to the open model….. Yep, security needs changed from simple to more complex…. I remember back when Java Applets were born. This was great, awesome, write once, distribute everywhere…. We started to jump on that band wagon… Wasn’t long and no, can’t use that technology as it was ‘exploited’ …. So we shut down those projects. That’s the reality of today though. You can’t develop anything connected without thinking first about security. Why the industry I work in now has CIP standards to follow….

          1. I think it’s crazy that Flash was killed off. So it had some problems, why not fix them?! If someone still wants to have Flash stuff on their website, they can install Ruffle, a Flash player written in the Rust language. It can be loaded from a web server and run the Flash app or animation, or it can be installed as a browser extension.

            There are ongoing attempts to kill off Java but it’s still around, despite nobody bothering to write a JRE for Android. There were a couple of commercial attempts/announcements but nothing ever came of them. I keep the official Java installed because I have some network printers that require Java for their print servers’ web admin.

        2. The concept of packets and a distributed system was intended to survive war. But arpanet was about sharing resources, so someone at university A could use the computer at university B. They decided it was a good way to try out packet switching. Once online, protocolsand other uses were implemented, a living laboratory.

  8. I remember going to a public talk given by a large R&D firm in Boston in the late 70’s about this.
    I thought it was a bad idea then.
    I still think it’s a bad idea.
    Lots of cheaper and safer ways to do this. Panels + wind and batteries is at the front of my list. Modern nukes comes next.
    Problems with SBSP:
    4)(slight) increase in global energy input
    and the list goes on.
    Government should be investing heavily in flow battery solutions.

    1. Put several adjectives before “slight,” please…

      The energy input increase is negligible. The amount of solar irradiance is around 3.86 x 10²⁶ W, so even a PetaWatt solar array would be 1×10¹⁵ W, about 11 orders of magnitude smaller.

      So “astonishingly negligible indetectable slight” would be a good one.

    2. The original proposals were for a Lunar base. Mass drivers to put materials into orbit. Manufacturing in high Lunar orbit then move to Earth geosynchronous. Expand Lunar base. Build ships for exploration. Begin construction of space colony cylinders, etc. It was a way to finance early stages of living on the Moon. And to end power production that produced CO2.9

  9. > (…) the best strategy to power our societies is to keep building nuclear plants (…)

    Is that an unbiased view on the alternatives? And if you dig into the ecological details, nuclear energy even isn’t climate friendly.

    1. Define friendly?

      Nuclear power stations produce no greenhouse gas in use, last a very very long time so any produced in the creation is spread over many many years of use and if you have enough of them to make all the energy costs of building it, the Uranium mining and transport electric the greenhouse gas production is going to be nill (or at least so marginal it doesn’t count).

      Not to say there are not ENVIRONMENTAL costs to them, the fuel has to be mined, the transport infrastructure built/used etc, but significant climate costs are not an inherent part of using nuclear power.

  10. To be fair, bringing down even more of the sun’s energy to the earth’s surface is likely unwanted by most people. Considering how there has been plenty of proposals to do the opposite and instead block out the sun’s rays.

    There is likewise the issue of a high power RF beam literally being a weapon. It isn’t like microwave weapons are already a thing in use, don’t have to put massive ones into space as well…

    Then there is the question about energy storage.
    And frankly speaking, the grid doesn’t need all that much of it to reek in massive benefits. Even small amounts of local energy storage means that transmission lines can be kept at high utilization even throughout low hours. Effectively making the ROI of transmission infrastructure have a better outlook.

    And to be fair, localized energy storage both close to the load (in homes/businesses) and further out in the grid (switch yards, substations) is something that more or less will happen over time regardless.

    To be fair, a lot of wind energy producers do likewise see benefits of being able to take up power during off peak hours, store the energy and sell it later when they get better pay for it. And with current energy prices this is starting to become majorly viable.

    So grid scale energy storage is coming regardless if people want it or not.

    And when the grid has just a few percent of daily needs covered by storage things will become a lot more stable, and further investments into storage will suddenly be a proven concept with off the shelf solutions and not a wild new idea.

  11. If I recall correctly the safety interlock consisted of a ring of laser beams around the main microwave beam. Essentially creating a fence. When the laser beams are broken, the microwaves switch off, so no cooked aircraft or seagulls. Unless of course the military decides to switch off the safety and aim it at someone they don’t like. A pretty terrifying prospect.

    1. The safety is inherent. The transmitters need feedback from the receiver in order to achieve and maintain coherence. If coherence is lost the antenna pattern spreads to a level of being harmless. It is 20,000 miles away after all. This was all worked out in the 1970’s. I don’t know what it wasn’t mentioned.

  12. Gerard K. O’Neill figured out solutions to a lot of this over forty years ago with contemporary tech. That we aren’t just *doing* it today is kind of absurd.

    I’d say “Check out JSC-14898 to start to see what I mean.” but the copy on the NASA Technical Reports Server is literally a PDF scan of a xerox of a xerox of a random library’s microfiche copy, and it looks like refried ass. (Here it is anyway: )

    It contains the answer to the biggest question; “How do we get them up there?” Well, we don’t. You send up these construction modules, designed to fit in–at the time–the Shuttle cargo bay, and they literally just *extrude* the beams which make up the structure of the platforms. Here’s the relevant bits (From an original):

    Though, all things considered, I think it probably makes more sense simply rehabilitating the public image of nuclear power, when we literally have over half a century of additional advances in those disciplines since society wrote off the technology, and no new reactors are being commissioned. It’s like if society decided that cars were altogether too dangerous and gave up on automobile travel before the advent of the seatbelt, yet the industry engineers continued to advance to the current levels of automobile safety… Let them make some more cars, you know?

    1. That automated beam builder should have been put to use in orbit. I remember reading about it in magazine articles in the 1980’s. Such a thing could pack all the frame structure for a space station into a couple of compact packages. For more efficiency, design it so the building material magazines are easy to replace. Then additional beams cost less than the first batch because the machine stays in orbit instead of being thrown away and having to launch a new one every time more beams are needed.

      Just about everything needed to have a thriving space colonization and manufacturing development has already been invented and is sitting in storage rooms and warehouses around the world, or at least in designs that could be even easier and cheaper to build now than when they were first conceived. But what’s even better is so much of it, if it was patented back when it was new, is old enough the patents have expired.

      Some company could make the effort to dig through old science and technology magazines and trade journals to find things like that beam builder, then use that information to track down any patents involved, and prototypes if they were made and still exist. Work with only expired patent technology and it couldn’t be stopped by the inventors or whomever patented the tech.

      1. I know, right? The beam builder is my favorite part! It’s freakin’ brilliant, and they were doing that with late 1970s tech!!! Think of the strength-to-weight difference in switching the main structure of the beams from strips of thermoformed prepreg fiberglass composite to carbon fiber composite. And imagine if the material magazines could be swapped out by something like one of those robotic satellite refuelers that everyone seems to be experimenting with the feasibility of right now.

        That last bit of yours sounds like a job for Elon Musk… All he seems to know how to do is throw his wealth at realizing ideas that much smarter people had decades ago. Which, in a way is doing a not-insignificant service to humanity; someone’s gotta take the financial risk to back radical technological advances that have yet to be made in the *decades* since they were first conceived simply because no one wants to pony up the cash. Might as well be him, even if he is kind of an obnoxious git. 🤔

  13. The weapons applications of these orbital solar farms have been explored in science fiction literature for many many decades. From microwaving square miles of dirt, to cancers on unsuspecting people, to lasing cities at a time. And there is no mechanism for mitigating it.

  14. I’m confused by whether the distances mentioned in the article are linear or area units, but even if area, sounds like the receiving area antenna is 10x as large as the solar energy density in space. So we are talking one tenth the energy density of full sunlight. Not much of a death ray in the event steering broke.

    I think I’d prefer 10 distributed panel sets in the desert. Seems a lot easier to build and service.

  15. Presumably we get cut off from the supply when there’s an eclipse?

    The power transmission back to Earth seems to be the ideal reason to invoke Nikolai Tesla’s long-range transmission techniques. Could generate some interesting aurora borealis effects.

  16. You forgot to mention geothermal, which has a lot of the advantages of nuclear without all that pesky radioactivity. It’s geographically limited at the minute, but heat mining is going to eliminate that issue soon, it seems.

    1. I like where at 1:20 in the video, he refers to kWh as kilometer watt hours.
      So, with geosynchronous orbit at 36000 km, those kilometers and start to add up!

  17. Where are the laws to friendly suggest/strongly encourage/force house owners to cover their roofs with solar?

    Once we get that fixed we’re allowed to dream of going ballistic.

  18. For the moon, perhaps, but for Earth?? NO!

    The losses we experience in transit end up as heat in the atmosphere. Depending on the weather patterns you’ll see more severe storms, not less.

    But on Earth, with nuclear, we can take “waste heat” and use it to do industrial processes (notice I did not say heat homes!). We don’t get that option in orbit where it’s infinitely more difficult to do.

  19. Seems to me like a massive amount of initial energy to get the things up there. If we had a moon base fully capable of autonomy and manufacturing these without earth assistance the initial energy cost would be much lower. But then again, what is the energy cost to build said moon base?
    I heard of a project to create solar based steam power, but coal had a cheaper initial cost… so guess what we got? Not to mention the military industrial complex required portable power for war ships and eventually tanks and planes.
    I still wonder why we dont use solar steam powered machines for energy generation or even just massive desalination plants. After the initial cost they are very effective and last quite some time with maintenance and have low to no emissions after the build cost.

      1. At scale. Mr sarcasm. Changed to oil around wwi when england started rolling out ships based on oil products rather than coal. The sentence was structured around portable power. But thanks for reading all the way through all the comments just to have a sarcasm all over tje face of my comment. Must not have much better to do. Lols.

  20. I vaguely remember an old Sci-Fi show in the 90s that had an episode where a SBSP was turned on and a terrorist or criminal or something hacked it to redirect the microwave and attack the city. Was a nice show but I don’t remember what it’s called.

    Either way, I feel like the main issue with any SBSP is maintenance. Parts of the US can’t maintain their exiting power infrastructure, and this would require trips to/from space to maintain.

  21. Since no one has mentioned it yet, check out the 1985 kiwi film The Quite Earth starring Bruno Lawrence. Admittedly the SBSP only serves as a backdrop, but a great scifi film none the less!

  22. What a lot of people are missing is that SBSP doe snot need to directly compete with ground based solar to be viable. It only needs to compete with the ‘last percent’ ground based solar plus battery (or other storage) installed capacity required to complete weaning off of fossil fuels.

    For example, you need 100TW of actual generation continuous (yes, demand cycles per day, this is just to avoid having to post a whole multivariable spreadsheet). A solar array of 100TW installed capacity will generate 100TW at peak conditions (midday hours, no clouds) but can fall below 10% capacity factor during cloudy mornings and evenings (and of course 0% at night). Now you are faced with a problem: you need both ~1200 TWh of battery capacity to supply your load, and some additional capacity for sub-100% capacity factor during the day. Or you can increase your installed solar capacity (e.g. 1PW installed capacity). Or some combination of the two. From this, it is clear that your 100TW solar array gets you to somewhere between 10% and 50% of total power demand, but getting that remaining 50% to 90% of required actual generation costs MUCH more than just adding the same sized array again.

    And that’s where SBSP has a niche: 24/7 generation without random variance at close to the design capacity factor. Other baseload generation schemes exist, so SBSP only needs to compete with them. Coal/Oil/Gas are right out once you actually count the externalities of the carbon emissions (e.g. add CC&S costs to generation costs, add mining costs, add exhaust particulate scrubber costs, etc). Nuclear is then the remaining major competitor, and whilst I’m a big proponent of Fission reactors, they do remain expensive, even if that expense if often higher than required due to legacy regulatory requirements (we’re not building RMBKs or BWR-3s).

    There’s also the fringe logistical benefit of being able to roll out reliable constant power supply wherever you can deploy a sparse antenna array, without needing to then truck in combustibles or deal with variable solar. That has obvious applications for both military use (no fuel truck supply chain to be cut) and disaster recovery (only need to fly in a few TEUs, not a few TUEs per day) which are even more tolerant of cost per unit installed capacity and can help to make the business case for initial setups.

    1. Unless you can stack ground solar and the ground station for SBSP ontop of each other its a hiding to nothing – it needs too much land area if keeping the supplied beam low enough intensity to be ‘safe’…

      It might be a theoretically reliable supply but it consumes too much land area on which you could just oversupply the solar PV and HW panels enough that even on their lowest output days you are meeting most of the load so don’t need vast areas of life limited and expensive battery…

      Along with being nearly impossible and rather expensive to maintain the space based elements for now at least, and the pesky atmosphere making efficiency likely rather low.. Yes starship and the like are on the horizon, bringing a return to being able to send astronauts up with all the required repair equipment etc. But we are not there yet and anything that huge and close to Earth will definitely take many micro meteorite type hits so need repair.

      SBSP if you can create a tight enough beam to me really makes sense as a way to fuel deeper space exploration and Mars colonies etc – you put the station(s) out there in that ballance of close enough orbit to the sun to get good solar intensity (so they don’t have to be so large) and not too far from the target the beam diverges too much… And being in space with nothing to hit the beam can be really high intensity safely, and will safely disperse long before it reaches anything out of the solar system..

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