Submitted by larsschellhas t3_124pxcz in space

I'm really into space and also into energy technology. And while space-based solar power appeared to just not be worth it, SpaceX's advancement in driving down cost is really bringing it into the realm of the possible now. Last year, Roland Berger and Frazer Nash even made studies for ESA showing that SBSP might become the most affordable baseload-able power source!

What do you think about space-based solar power? Will SBSP power humanity in the decades to come?

In case you haven't heard from it before, I've tried to summarise what I was able to learn about it in this article :)



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ferrel_hadley t1_je0ev4c wrote

How long will it take to get the same amount of energy back to Earth from 1 tonne of solar arrays as it costs to get that 1 tonne to the relevant orbit?

If the answer is a year, then yes. If its 20 years then unlikely.

Energy cost will be your hard floor, if it takes too long to get the energy back then you are wasting your time. Above that comes the economics, how much can you get from consumers for 1 tonne on orbit vs the cost of getting it there. This is a bit more flexible as you can work on the non fuel costs.

Space does offer advantages, you can almost always be at 90^(0) to the Sun and you can have less atmosphere to get through. Its also almost always very sunny. It has disadvantages like the current insane cost to orbit and the difficulties getting energy once you move beyond the tropics and into more oblique angles.

The current answer is a very loud no with current technology. The point where no becomes yes is one of engineering and economics and an open question if you consider current costs to orbit easy to cut.


larsschellhas OP t1_je0hg54 wrote

Well, starship is aiming to bring launch costs down to as low as 10 $/kg.

At that price SBSP would still be slightly more expensive than solar and wind, but much cheaper than storage, backup & peak load technologies which we will be needing in a purely renewable system anyway.

SBSP has the big advantage that it can deliver power to many markets, simply by switching to another base station. Thanks to this, it can capture much higher wholesale prices for electricity than wind and solar.

Essentially, it could capture 24/7 peak power prices, putting it at a better position than ground-based wind and solar even though it has higher levelised cost of energy.


EnigoMontoya t1_je0mila wrote

Bunch of questions here, but starting with a couple...

What's your assumption on the cost of the distributed ground based plants accepting SBSP on a $/MW basis?

What's the breakdown of percent loss from SBSP for the transmission down to ground and conversion into usable AC?


larsschellhas OP t1_je0yd9s wrote

It's around 50% at the moment, but has no physical limit really. The advantage of microwaves (like Radar) is that they are much less impacted by clouds and weather than visible light.

The receiver stations are also simple antennas which can be manufactured much cheaper than solar PV, therefore making up only a small share of the total CAPEX. I don't have the number off the top of my head, but they can be found in the Roland Berger and Frazer Nash studies.


EnigoMontoya t1_je11jm3 wrote

Right so the conversion is 50% but the transmission over distance is a distinct loss correct? Yes, microwaves can penetrate the atmosphere, but there is still a cost.

This diagram from a 2021 study touting a 45% conversion efficiency but notes a huge drop from the transmission... 400 KW -> 10 KW over just 10 KM.

When you consider geosynchronous orbit is all the way out at 35,000 KM. This seems like a major issue. What am I missing?


larsschellhas OP t1_je11s3v wrote

That there are only around 10-50 km of atmosphere is the way and that accuracy is the primary driver of losses. :)


larsschellhas OP t1_je1rz1o wrote

Or rather, according to EMROD, the main loss driver is the conversion to microwaves. Reconversion and transmission appear to be relatively efficient.


Brain_Hawk t1_je16al7 wrote

That $10 per kilogram is an extremely optimistic estimate cited by a person who was well known to exaggerate in order to drive interest and investment.

Personally I suspect it's going to be quite a bit more than that, not that I'm an expert on launch cost. But I think we need to be a bit more skeptical of the claims being made at this time.

To the bigger question, I think any technology may be feasible in the future, but as far as I can see there's still a lot of challenges with orbital-based power. In particular the cost of sending it up and maintaining it, and the amount of power we can get generated back down on earth, and distributing that to a wide area.

But, if we don't come up with a better solution, it's definitely something I can see being in place in the next 50 or 100 years.


electric_ionland t1_je0ee5y wrote

If you are promoting your own article you should probably just say so...


larsschellhas OP t1_je0i7cv wrote

I wasn't trying to promote it... 😔 I've just been down a whole rabbit hole the last weeks realising that ESA, Airbus, and Co. are all over the topic and I wanted to learn everything I could. There is even a government initiative in the UK now (

I've been really excited about it and wanted to discuss with some likeminded people here, just sharing the background for those who haven't heard of it.

Didn't expect to be completely overwhelmed with 100 % underwhelmed reactions though. Really making me sad right now.


electric_ionland t1_je0lqe5 wrote

It's fine, but implying that you just found that article rather than wrote it is more than a bit disingenuous.

My personal take as an aerospace engineer is that I find it hard to believe that the benefit of better illumination outweigh the complexity and cost of a project like that.


larsschellhas OP t1_je0to7w wrote

>I've tried to summarise what I was able to learn about it in this article :)

I literally wrote that I wrote the article myself.... 🙈

Yes, I get that. I'm an energy/mechanical engineer, and working as management consultant for the energy industry. It's a hard case. But the problem of renewables right now really is their intermittency... Solar PV has a load factor of 11-16 % over the course of the year, but in winter weeks you can easily get load factors of 1 %.

Space-based solar power can achieve close to 100 % load factor and delivers equally in summer and winter. From the value side, it provides much more than wind and solar do right now. But the cost side, of course, is also much more intensive. However, it appears to become economically feasible with launch costs decreasing further and further. If not as baseload than at least as peak capacity.

ESA is currently running two studies (results expected in the next months) which are expected to show that the cost of such a system could actually be further reduced if we were to use materials from the Moon.


Crenorz t1_je0abod wrote

Silly. We need what 0.02% of the earth's land for enough solar for the planet??? And that excludes water. So why pay more to put it in space? Too easy to do it on land?


solidcordon t1_je0awt5 wrote

There is a small advantage for solar collectors in geosynchronous orbit in terms of time in sunlight.

There is a small disadvantage in the sense that a high power microwave transmitter in geosych orbit can be used as a weapon of mass destruction.


larsschellhas OP t1_je0didg wrote

They receive 8 times more energy per year than ground-based solar power. Even if you lose 50 % during transmission you get a) 4 times the power than on Earth with the same capacity b) continuous power supply throughout the year.

And if anyone is going to be allowed to build a SBSP satellite, it will include power beaming designs which are inherently safe and cannot be used for "mass destruction".


How about using it to power the moon base or rovers first, who otherwise remain in the long cold night of the moon?


solidcordon t1_je1ll86 wrote

I'm not sure that there is a way to engineer something that would "prevent it being weaponised".

Nation states are likely prohibited by treaty from putting one in orbit, not sure why a private company should be allowed to do so.

In terms of using it for lunar colonisation the same problems arise but there's no treaties preventing it.

In terms of environmental benefit... all the power you lose forcing the microwave transmission through the atmosphere is energy that would not have been added to the Earth's budget otherwise. Attenuation in the air is drastically increased by water content, so cloudy / rainy areas are not great for receiving stations.

It's not a bad idea in principle and it's well within our capabilities from an engineering perspective but there is no world leader / private individual / council of wise pacifists I would trust with control.


Psychomadeye t1_je0x6vr wrote

>And if anyone is going to be allowed to build a SBSP satellite, it will include power beaming designs which are inherently safe and cannot be used for "mass destruction".

Where's the fun in that?


larsschellhas OP t1_je0xv97 wrote

True, I'd love some death beams, too! 🤣


Psychomadeye t1_je0ycm3 wrote

When I think of space lasers I think about using them to deflect asteroids. It would be kind of cool to beam them down to earth for power, but right now it's definitely not worth it. We could probably get the most bang for our buck by saving power.


larsschellhas OP t1_je0yqpt wrote

Probably easier to throw a small rock against the asteroids early on in their trajectory though :D


Psychomadeye t1_je9zwfb wrote

Yes, but I'm thinking we could reach it faster, and from further this way, and apply more energy in total. I'm not suggesting it would be worth it, more that it's a fun thing to think about.


larsschellhas OP t1_jea0m0x wrote

True. And it might be worth it overall. Like, a laser would evaporate ice and material on the asteroid, which would push away from the asteroid, changing its trajectory.


larsschellhas OP t1_je0d558 wrote

It could be overall cheaper. What you also need for solar power on the ground is storage, storage, storage, and 10x the capacity, because you won't produce enough in the winter.

SBSP could go hand in hand with ground-based systems providing the necessary dispatchable baseload or peak power, enabling a truly renewable system without expensive backup power stations.


andygates2323 t1_je1pa4y wrote

Cheap bulk launch is a prerequisite, just like it is for lots of cool big space projects.


larsschellhas OP t1_je1rr60 wrote

True. And we are strongly getting there. Cheap bulk launch is already here compared to 10 years ago. Where will we be in 10 years from now?


andygates2323 t1_je1tlwb wrote

Still needs an order of magnitude more bulk, more cheapness. Starship is one to watch.


larsschellhas OP t1_je1w6ed wrote

Absolutely. But Spacex won't remain the single cheap reusable launcher. Competition will catch up and then the real race begins.


LunaticBZ t1_je1hzbv wrote

Hey OP question have you watched Isaac Arthur's video on power satellites?

I don't remember how much detail the video goes into, but there's links in the description for more reading and sources usually

Personally I think we will do some power satellites for Earth, but I doubt it becoming a major power component. My view is based on a lot of assumptions about the future though.


KetoRachBEAR t1_je2288h wrote

Starship could pioneer the way for space based manufacturing, making it possible in the near future


Psychomadeye t1_je0xsem wrote

This doesn't feel like the right place for this. But to answer your question, no.