On beaming solar power from low earth orbit(innovationfrontier.org)
innovationfrontier.org
On beaming solar power from low earth orbit
https://innovationfrontier.org/space-solar-power-an-extraterrestrial-energy-resource-for-the-u-s/
88 comments
Even if the "cost" of getting the required infrastructure into orbit (assuming Earth-based manufacturing) was close to zero, the energy requirements would still eat up the benefits.
SSP only works if every piece of the orbital infrastructure is sourced and built outside of Earth's gravity well.
But that's not even the main concern with such system. The primary reason we won't see anything like this anytime soon is the simple fact that such system can easily be weaponised. An SSP is basically a potential space-based weapon. Even if there's no intention to use it as such, some governments are pretty much guaranteed to see it that way and proceed to install actual space-based weaponry in orbit.
SSP only works if every piece of the orbital infrastructure is sourced and built outside of Earth's gravity well.
But that's not even the main concern with such system. The primary reason we won't see anything like this anytime soon is the simple fact that such system can easily be weaponised. An SSP is basically a potential space-based weapon. Even if there's no intention to use it as such, some governments are pretty much guaranteed to see it that way and proceed to install actual space-based weaponry in orbit.
> An SSP is basically a potential space-based weapon
Asteroid mining has a similar problem.
Any tech that can send a metal asteroid to Earth orbit can also smash it into Buenos Aires.
Asteroid mining has a similar problem.
Any tech that can send a metal asteroid to Earth orbit can also smash it into Buenos Aires.
Any tech that can send a 1 ton roadster to mars can crash a 1 ton roadster into Buenos Aires at 20,000mph
Obviously. It all started as a way to drop bombs on London, and we are only now reaching a time where the majority of rocket models are not derivatives of ICBMs.
Spaceflight is a story of a military technology finding civilian use. That has a very different ring to it than civilian technology being used as a weapon, even if the effect is similar.
Spaceflight is a story of a military technology finding civilian use. That has a very different ring to it than civilian technology being used as a weapon, even if the effect is similar.
Wouldn't the car disintegrate in the atmosphere?
The car would obviously be a poor choice as a weapon. A big tungsten rod on the other hand...
https://en.wikipedia.org/wiki/Kinetic_bombardment
https://en.wikipedia.org/wiki/Kinetic_bombardment
Air resistance limits small kinetic kill weapons. Square cube law however means it’s less effective for larger objects.
1 ton tungston rod wouldn't burn up.
A 1 ton rod would loose most of it’s kinetic energy on reintry.
“A system described in the 2003 United States Air Force report[9] was that of 20-foot-long (6.1 m), 1-foot-diameter (0.30 m) tungsten rods that are satellite-controlled and have global strike capability, with impact speeds of Mach 10.“
That’s 1.725m2 of tungsten at 19,280kg/m2 = 33.2 metric tons and it’s still only doing Mach 10 on impact.
“A system described in the 2003 United States Air Force report[9] was that of 20-foot-long (6.1 m), 1-foot-diameter (0.30 m) tungsten rods that are satellite-controlled and have global strike capability, with impact speeds of Mach 10.“
That’s 1.725m2 of tungsten at 19,280kg/m2 = 33.2 metric tons and it’s still only doing Mach 10 on impact.
just make the large object split into many small kill weapons not far from the target(s).
A one ton roadster will burn up before it does anything, a large factory will not:
>About once a year, an automobile-sized asteroid hits Earth's atmosphere, creates an impressive fireball, and burns up before reaching the surface.
>Every 2,000 years or so, a meteoroid the size of a football field hits Earth and causes significant damage to the area.
https://www.nasa.gov/mission_pages/asteroids/overview/fastfa...
>About once a year, an automobile-sized asteroid hits Earth's atmosphere, creates an impressive fireball, and burns up before reaching the surface.
>Every 2,000 years or so, a meteoroid the size of a football field hits Earth and causes significant damage to the area.
https://www.nasa.gov/mission_pages/asteroids/overview/fastfa...
Think of the speeding ticket Elon will get.
It doesn’t even have to be intentional.
Maybe China will build such a system, not because it makes economic sense, rather for national prestige, so they can claim to be ahead of the US in that technology. Even if they spend a few billion for a modest sized demonstration system, that’s only a fraction of their national budget.
How would the US respond? Possibly Congress will respond by paying to build its own bigger one, again not for the economics, simply for the prestige.
I am not sure anyone will care that much about the “space-based weapon” angle. If it is a weapon, you just build your own and then you have one too, and now both sides have that weapon. The ability to have a (possibly illegal) space-based weapon yet publicly insist it is just a (completely legal) power generation demonstrator may even be attractive to military planners on both sides. However, in practice, a modest sized technology demonstrator may be quite limited in the damage it can inflict, unless it was enhanced with extra hardware that made it more obviously a weapon, and harming its plausible deniability.
How would the US respond? Possibly Congress will respond by paying to build its own bigger one, again not for the economics, simply for the prestige.
I am not sure anyone will care that much about the “space-based weapon” angle. If it is a weapon, you just build your own and then you have one too, and now both sides have that weapon. The ability to have a (possibly illegal) space-based weapon yet publicly insist it is just a (completely legal) power generation demonstrator may even be attractive to military planners on both sides. However, in practice, a modest sized technology demonstrator may be quite limited in the damage it can inflict, unless it was enhanced with extra hardware that made it more obviously a weapon, and harming its plausible deniability.
There's no need for space based weapons when hypersonic missiles can deliver megatonne grade nuclear arsenals "easily" today.
But framing it as a weapons system, to attract military funding (which ultimately ends up as useful civilian technology) isn't so bad.
But framing it as a weapons system, to attract military funding (which ultimately ends up as useful civilian technology) isn't so bad.
Is it? Article claims 2 GW / 30 km², which is ~70 W/m², a fraction of solar irradiance in most places.
Sort of yes, sort of no.
If there is at most one space based solar energy system visible from any given point on the ground, you can make strong safety claims based on wavelength and antenna size.
However, if you limit yourself to one in any given sky, you necessarily either (1) put them in high orbit so they do useful things in local night, limiting you to a small total count planet-wide, or (2) put them in a low orbit, which means you can’t use them in local nighttime.
If you want nighttime coverage and enough of these systems to be relevant to global power — and the current nameplate capacity of ground-based PV is just under a terawatt — you have to worry about multiple orbit-to-ground beams being directed at the same spot.
While you could have up to about half a dozen giant ground-station for half a dozen giant beams, that needs ground level transmission over a significant fraction of the surface to be relevant to global energy needs, at which point you might as well make a planetary scale power grid and get your nighttime supplies from a mixture of the rooftops on the other side of the planet and some convenient deserts your energy supplier is renting.
If there is at most one space based solar energy system visible from any given point on the ground, you can make strong safety claims based on wavelength and antenna size.
However, if you limit yourself to one in any given sky, you necessarily either (1) put them in high orbit so they do useful things in local night, limiting you to a small total count planet-wide, or (2) put them in a low orbit, which means you can’t use them in local nighttime.
If you want nighttime coverage and enough of these systems to be relevant to global power — and the current nameplate capacity of ground-based PV is just under a terawatt — you have to worry about multiple orbit-to-ground beams being directed at the same spot.
While you could have up to about half a dozen giant ground-station for half a dozen giant beams, that needs ground level transmission over a significant fraction of the surface to be relevant to global energy needs, at which point you might as well make a planetary scale power grid and get your nighttime supplies from a mixture of the rooftops on the other side of the planet and some convenient deserts your energy supplier is renting.
> put them in high orbit so they do useful things in local night, limiting you to a small total count planet-wide
Geostationary orbit is a circle over the equator with radius 42241 km, circumference 265408 km.
Yes, it's "limited" in the sense that it's finite, but it's not exactly small.
In its current primary use, communication satellites, there is a problem with interference; things like residential TV-sat dishes need to be small, so they have limited resolution, so those satellites need to be relatively far apart. That is not an issue for space based solar power.
> put them in a low orbit [...] worry about multiple orbit-to-ground beams being directed at the same spot
From different directions, at different times.
Geostationary orbit is a circle over the equator with radius 42241 km, circumference 265408 km.
Yes, it's "limited" in the sense that it's finite, but it's not exactly small.
In its current primary use, communication satellites, there is a problem with interference; things like residential TV-sat dishes need to be small, so they have limited resolution, so those satellites need to be relatively far apart. That is not an issue for space based solar power.
> put them in a low orbit [...] worry about multiple orbit-to-ground beams being directed at the same spot
From different directions, at different times.
I think you’ve misunderstood the problem I’m describing, so I’ll see if I can rephrase.
The limit is not how many physically fit in geostationary orbit — I agree that’s fine — it’s that if more than one such system is in your sky (Edit: that is, above your horizon) then you need to care what happens if all the different ones in your sky (above your horizon) target your location at the same time.
>> put them in a low orbit [...] worry about multiple orbit-to-ground beams being directed at the same spot
That ellipsis is combining different scenarios.
The limit is not how many physically fit in geostationary orbit — I agree that’s fine — it’s that if more than one such system is in your sky (Edit: that is, above your horizon) then you need to care what happens if all the different ones in your sky (above your horizon) target your location at the same time.
>> put them in a low orbit [...] worry about multiple orbit-to-ground beams being directed at the same spot
That ellipsis is combining different scenarios.
> you need to care what happens if all the different ones in your sky (above your horizon) target your location at the same time
No, you don't need to, because they don't need to.
>>> put them in a low orbit [...] worry about multiple orbit-to-ground beams being directed at the same spot >> >> That ellipsis is combining different scenarios.
Only if you insist that "about half a dozen giant ground-station for half a dozen giant beams" is the limit for what can be put in geostationary orbit, which you now seem to acknowledge is not true.
No, you don't need to, because they don't need to.
>>> put them in a low orbit [...] worry about multiple orbit-to-ground beams being directed at the same spot >> >> That ellipsis is combining different scenarios.
Only if you insist that "about half a dozen giant ground-station for half a dozen giant beams" is the limit for what can be put in geostationary orbit, which you now seem to acknowledge is not true.
I don’t understand how you can assert what you’re asserting, especially as you appear to be claiming to read my mind despite the paragraph break you cut with the ellipsis.
Hypothetical scenario: 1000 satellites evenly arranged around geostationary orbit, each beaming 1 GW to a ground station.
Now hackers point all the ones visible to NYC at NYC.
How do you guarantee this does not happen? I can only think of two options: (1) small number of big satellites (down side being centralisation); (2) low orbit (downside being no nighttime power because they’re now in shade at local night).
I say you must not allow this hypothetical to happen. This is a safely limit, and it never has anything to do with the volume of the orbit. It is still a limit.
Hypothetical scenario: 1000 satellites evenly arranged around geostationary orbit, each beaming 1 GW to a ground station.
Now hackers point all the ones visible to NYC at NYC.
How do you guarantee this does not happen? I can only think of two options: (1) small number of big satellites (down side being centralisation); (2) low orbit (downside being no nighttime power because they’re now in shade at local night).
I say you must not allow this hypothetical to happen. This is a safely limit, and it never has anything to do with the volume of the orbit. It is still a limit.
> Now hackers point all the ones visible to NYC at NYC.
What you just did there is called moving the goalposts.
The discussion up to that sentence was about constraints imposed by orbital geometry. You claimed incorrectly that the "limited" space available in geostationary orbit would allow "up to about half a dozen giant ground-station for half a dozen giant beams", concluded that it would therefore be necessary to use LEO instead (it's not), and (again incorrectly) jumped to the conclusion that this would necessarily imply multiple beams on the same target.
Neither you nor anybody else said anything about sabotage.
> This is a safely limit, and it never has anything to do with the volume of the orbit.
Actually you just threw away your original argument and made up a whole new one.
> How do you guarantee this does not happen?
I don't. I also don't guarantee that terrorists won't fly airliners into skyscrapers or put a nuclear device in a container and ship it to New York's harbor. Yet we keep building skyscrapers, flying airliners and shipping containers across the world, despite the obvious risks, because the advantages of doing so outweigh those risks.
The specific risk in question is not even all that hard to mitigate, especially when you're dealing with large stations in geostationary orbit, each targeting a limited set of fixed locations (which would be dedicated receiver arrays, not cities). You put fail-safes on station which are hardwired to track antenna orientation and shut down the beam if it strays from its target. Now all your hypothetical hackers can do is interrupt the beam until you regain control, which is irritating but nothing new:
https://en.wikipedia.org/wiki/Ukraine_power_grid_hack
What you just did there is called moving the goalposts.
The discussion up to that sentence was about constraints imposed by orbital geometry. You claimed incorrectly that the "limited" space available in geostationary orbit would allow "up to about half a dozen giant ground-station for half a dozen giant beams", concluded that it would therefore be necessary to use LEO instead (it's not), and (again incorrectly) jumped to the conclusion that this would necessarily imply multiple beams on the same target.
Neither you nor anybody else said anything about sabotage.
> This is a safely limit, and it never has anything to do with the volume of the orbit.
Actually you just threw away your original argument and made up a whole new one.
> How do you guarantee this does not happen?
I don't. I also don't guarantee that terrorists won't fly airliners into skyscrapers or put a nuclear device in a container and ship it to New York's harbor. Yet we keep building skyscrapers, flying airliners and shipping containers across the world, despite the obvious risks, because the advantages of doing so outweigh those risks.
The specific risk in question is not even all that hard to mitigate, especially when you're dealing with large stations in geostationary orbit, each targeting a limited set of fixed locations (which would be dedicated receiver arrays, not cities). You put fail-safes on station which are hardwired to track antenna orientation and shut down the beam if it strays from its target. Now all your hypothetical hackers can do is interrupt the beam until you regain control, which is irritating but nothing new:
https://en.wikipedia.org/wiki/Ukraine_power_grid_hack
I am not going to make a further attempt to show you that my position is consistent or rephrase anything.
If you are unable or unwilling to understand that all of my comments in this sub-thread are consistent, that there is no goalpost moving, and that I am demonstrating the flaws with each possible configuration and thereby excluding the whole, this conversion is over.
You falsely claim I said this is about limited space. I didn’t use the word “limited” until now, and wrote of half a dozen orbital components right next to saying why it’s bad to have more, without claiming it was impossible.
You falsely claim I’m moving the goalposts, when I said it was about safety of overlapping beams in first thing you replied to.
In point of fact, the half-dozen number wouldn’t even be geostationary in the scenario I was envisioning, which ought to have been obvious from even a cursory moment’s thought. If you feel like working out what this scenario actually was instead of arguing against things I did not write, feel free, but I won’t bother looking much less replying.
One misunderstanding is on me, but this many isn’t worth the effort.
If you are unable or unwilling to understand that all of my comments in this sub-thread are consistent, that there is no goalpost moving, and that I am demonstrating the flaws with each possible configuration and thereby excluding the whole, this conversion is over.
You falsely claim I said this is about limited space. I didn’t use the word “limited” until now, and wrote of half a dozen orbital components right next to saying why it’s bad to have more, without claiming it was impossible.
You falsely claim I’m moving the goalposts, when I said it was about safety of overlapping beams in first thing you replied to.
In point of fact, the half-dozen number wouldn’t even be geostationary in the scenario I was envisioning, which ought to have been obvious from even a cursory moment’s thought. If you feel like working out what this scenario actually was instead of arguing against things I did not write, feel free, but I won’t bother looking much less replying.
One misunderstanding is on me, but this many isn’t worth the effort.
>> You falsely claim I said this is about limited space. I didn’t use the word “limited” until now
This is what you wrote:
> put them in high orbit so they do useful things in local night, limiting you to a small total count planet-wide
Do you seriously wish to claim this is not a statement about limited space?
> You falsely claim I’m moving the goalposts, when I said it was about safety of overlapping beams
Nobody is disputing that your original argument was about the safety of overlapping beams. You moved the goalposts when you replaced that argument, which was based on your incorrect understanding of orbital geometry, with one about intentional sabotage ("hackers point all the ones visible to NYC at NYC").
> In point of fact, the half-dozen number wouldn’t even be geostationary in the scenario I was envisioning, which ought to have been obvious from even a cursory moment’s thought.
The article linked at the top of this page (you know, the thing we are supposed to be discussing) is about a development program which starts with a LEO demonstrator, followed by a larger MEO demonstrator, followed by GW-class stations in geosynchronous orbit. The latter are the standard commercial scenario which has been envisioned since the 70s.
If you had another scenario in mind, you "forgot" to say so. Again. Even while confirming that the "limit is not how many physically fit in geostationary orbit — I agree that’s fine".
> One misunderstanding is on me, but this many isn’t worth the effort.
No problem, it was obvious from your first reply that you're not interested in a factual discussion.
This is what you wrote:
> put them in high orbit so they do useful things in local night, limiting you to a small total count planet-wide
Do you seriously wish to claim this is not a statement about limited space?
> You falsely claim I’m moving the goalposts, when I said it was about safety of overlapping beams
Nobody is disputing that your original argument was about the safety of overlapping beams. You moved the goalposts when you replaced that argument, which was based on your incorrect understanding of orbital geometry, with one about intentional sabotage ("hackers point all the ones visible to NYC at NYC").
> In point of fact, the half-dozen number wouldn’t even be geostationary in the scenario I was envisioning, which ought to have been obvious from even a cursory moment’s thought.
The article linked at the top of this page (you know, the thing we are supposed to be discussing) is about a development program which starts with a LEO demonstrator, followed by a larger MEO demonstrator, followed by GW-class stations in geosynchronous orbit. The latter are the standard commercial scenario which has been envisioned since the 70s.
If you had another scenario in mind, you "forgot" to say so. Again. Even while confirming that the "limit is not how many physically fit in geostationary orbit — I agree that’s fine".
> One misunderstanding is on me, but this many isn’t worth the effort.
No problem, it was obvious from your first reply that you're not interested in a factual discussion.
The game changer here is SpaceX's Starship. If you can lift 100T to orbit in one shot, that suffices to deploy around 6 MW worth of the current solar panels we use for the ISS, which clock in at around 120KW/2T. Solar panel efficiency has improved greatly since they were designed and built, so even accounting for the overhead of assembly, refueling, the transmission component etc, 10MW+ per launch seems quite feasible, particularly if Musk gets costs down to the mooted $20/kg or so.
Charlie Stross does the napkin math here: https://www.antipope.org/charlie/blog-static/2021/09/fossil-...
Charlie Stross does the napkin math here: https://www.antipope.org/charlie/blog-static/2021/09/fossil-...
Interesting. That's 0.20$/W on launch costs, what is actually not a showstopper.
I still doubt it will happen any time soon, because by the time we have enough launch capacity to use on things like this, the 0.2$/W will be a sizeable fraction of the costs of solar on the ground. The advantage is that you don't need batteries, but like photovoltaics, the floor on the costs of batteries is very low.
I still doubt it will happen any time soon, because by the time we have enough launch capacity to use on things like this, the 0.2$/W will be a sizeable fraction of the costs of solar on the ground. The advantage is that you don't need batteries, but like photovoltaics, the floor on the costs of batteries is very low.
Their math is wrong. The ISS solar panels plus supporting truss elements mass about 60t or 2KW/t. At the fantastical (unbelievable) $20/kg to LEO that's $10/W. That doesn't include the mass of thermal control elements, maneuvering systems, power conversion, or power transmission system.
Also that's only to LEO which is useless for an SPS since the system wouldn't dwell over any receiver on the ground long enough to transmit a useful amount of power. You'd need all that mass in a geosynchronous orbit which trebles or quadruples that cost.
Also that's only to LEO which is useless for an SPS since the system wouldn't dwell over any receiver on the ground long enough to transmit a useful amount of power. You'd need all that mass in a geosynchronous orbit which trebles or quadruples that cost.
You're missing a few details.
1. The current (public) Starship design has no facilities for cargo delivery. While it can lift a lot of mass it doesn't have doors to unload large payloads in space. SpaceX certainly can build cargo versions but that will require non-trivial changes to the craft. Cargo doors aren't load bearing structures.
2. Starship's "100t to orbit" is only to LEO. To get a payload to a better orbit you're going to need to also launch some sort of bus and lots of fuel. Even if it's just a buddy fueling Starship that's still more launches and rendezvous.
3. Musk's claims of $20/kg are unbelievable. He has a long colorful history or over promising and under delivering. A fully fleshed out Starship production pipeline will bring launch costs down but not that much. It'd be nice to be wrong but I'd take all of Musk's claims with a giant grain of salt.
4. You're vastly underestimating the amount of mass you'd need to put in orbit and then assemble. Solar panels aren't load bearing so they all need to be attached to some sort of support truss (like the ISS truss). Then you've got the power conversion system, thermal control system, maneuvering system, and power transmission system. Each of those systems will easily mass the same as the actual solar panels.
5. The ISS solar panels with the support truss elements mass about 60t [0], so they generate about 2KW/t. Assuming power conversion was 50% efficient (I think that's reasonable) a gigawatt SPS would need at least 1000t of panel assemblies with at minimum another 500t of supporting equipment/infrastructure. I'd argue the support structure would be at least 1000t.
6. To make that SPS even remotely useful you'd need it in a geosynchronous orbit, any lower and it would pass too quickly over the ground to transmit any power.
So an SPS, sending just a gigawatt of power to the ground, would require a minimum of 1500t (~4x ISS) launched into a geosynchronous orbit. That's in addition to the fuel and buses launched to facilitate construction. All of that is just for assembly. None of that counts the component construction on the ground of the space-qualified hardware.
Meanwhile a gigawatt of renewable power on Earth is orders of magnitude cheaper and doesn't require several square kilometers of rectenna on the ground. A bit of debris that breaks a ground based panel also won't cause a chain reaction that can destroy the entire installation.
[0] https://space.stackexchange.com/a/9758
1. The current (public) Starship design has no facilities for cargo delivery. While it can lift a lot of mass it doesn't have doors to unload large payloads in space. SpaceX certainly can build cargo versions but that will require non-trivial changes to the craft. Cargo doors aren't load bearing structures.
2. Starship's "100t to orbit" is only to LEO. To get a payload to a better orbit you're going to need to also launch some sort of bus and lots of fuel. Even if it's just a buddy fueling Starship that's still more launches and rendezvous.
3. Musk's claims of $20/kg are unbelievable. He has a long colorful history or over promising and under delivering. A fully fleshed out Starship production pipeline will bring launch costs down but not that much. It'd be nice to be wrong but I'd take all of Musk's claims with a giant grain of salt.
4. You're vastly underestimating the amount of mass you'd need to put in orbit and then assemble. Solar panels aren't load bearing so they all need to be attached to some sort of support truss (like the ISS truss). Then you've got the power conversion system, thermal control system, maneuvering system, and power transmission system. Each of those systems will easily mass the same as the actual solar panels.
5. The ISS solar panels with the support truss elements mass about 60t [0], so they generate about 2KW/t. Assuming power conversion was 50% efficient (I think that's reasonable) a gigawatt SPS would need at least 1000t of panel assemblies with at minimum another 500t of supporting equipment/infrastructure. I'd argue the support structure would be at least 1000t.
6. To make that SPS even remotely useful you'd need it in a geosynchronous orbit, any lower and it would pass too quickly over the ground to transmit any power.
So an SPS, sending just a gigawatt of power to the ground, would require a minimum of 1500t (~4x ISS) launched into a geosynchronous orbit. That's in addition to the fuel and buses launched to facilitate construction. All of that is just for assembly. None of that counts the component construction on the ground of the space-qualified hardware.
Meanwhile a gigawatt of renewable power on Earth is orders of magnitude cheaper and doesn't require several square kilometers of rectenna on the ground. A bit of debris that breaks a ground based panel also won't cause a chain reaction that can destroy the entire installation.
[0] https://space.stackexchange.com/a/9758
The naive engineer in me thinks that a baloon floating at 4k-5k meters above sea level, covered with solar panels, would still get most of the efficiency, but would also be cheaper and simpler to build.
Where am I horribly wrong?
Where am I horribly wrong?
Transmission loses would probably make a balloon a wash vs ground-based solar. Then there's the liability of some mass of solar panels floating over populated areas. At 5km an untethered balloon would have a fairly wide area it could land on. A 5km tether dragging around or falling on the ground could cause a lot of damage as well. There's also dangerous conditions when atmospheric conditions cause the balloon to lower its altitude, slacking the tether, and low altitude wind whipping it around. I don't see any utility of untethered balloons.
Various issues with this tech:
1. "A 2,000 MW SSP system would require a ground receiver covering about 30 square kilometers"
2. The satellite would be in geostationary orbit, or 22,000 miles up, so a directed microwave beam would need to be sent that distance in as tight a beam as possible, so likely the transmitter side on the satellite would be a large dish (to go along with the large surface area of the solar panels, so maybe if the solar panels are solved, then a large dish is ok)
3. Now, if you flew an airplane through that 30 sq km area what happens, or various wildlife like birds fly through that area? Slight cooking?
4. Likely that receiver can't be located near a city because people would be freaked out about being irradiated by a giant microwave beam, so you need transmission towers going across the land to the city you are hoping to power
5. If something goes wrong with your giant power plant in the sky you need to spend serious money to go up and try to fix it.
Or, you can dispense with all of that say, ok lets put up a 30 sq km solar array and a battery bank with it and just live with the fact that you don't get sun all of the time. Far cheaper and easier to maintain and upgrade in the future.
If this was a discussion about doing this from a space solar farm beaming energy down to mars, then that would be a different story since putting mass into orbit around a planet is cheaper than getting it onto the ground -- so it may actually make some reasonable sense for powering a mars base for some period of time rather than deploying tons of solar panels down on the surface of mars, then on the surface you come up with a low cost way to create some receiver that is low mass and ideally would be just a bunch of wire on a spool that somebody drives back and forth building up over a month or something.
1. "A 2,000 MW SSP system would require a ground receiver covering about 30 square kilometers"
2. The satellite would be in geostationary orbit, or 22,000 miles up, so a directed microwave beam would need to be sent that distance in as tight a beam as possible, so likely the transmitter side on the satellite would be a large dish (to go along with the large surface area of the solar panels, so maybe if the solar panels are solved, then a large dish is ok)
3. Now, if you flew an airplane through that 30 sq km area what happens, or various wildlife like birds fly through that area? Slight cooking?
4. Likely that receiver can't be located near a city because people would be freaked out about being irradiated by a giant microwave beam, so you need transmission towers going across the land to the city you are hoping to power
5. If something goes wrong with your giant power plant in the sky you need to spend serious money to go up and try to fix it.
Or, you can dispense with all of that say, ok lets put up a 30 sq km solar array and a battery bank with it and just live with the fact that you don't get sun all of the time. Far cheaper and easier to maintain and upgrade in the future.
If this was a discussion about doing this from a space solar farm beaming energy down to mars, then that would be a different story since putting mass into orbit around a planet is cheaper than getting it onto the ground -- so it may actually make some reasonable sense for powering a mars base for some period of time rather than deploying tons of solar panels down on the surface of mars, then on the surface you come up with a low cost way to create some receiver that is low mass and ideally would be just a bunch of wire on a spool that somebody drives back and forth building up over a month or something.
The receiving rectenna would be large, but from what I know it would basically consist of a spaced array of small vertical antennas.
The sat does not need to be in geostationary orbit and in fact a better solution is to have a constellation at lower orbits. This also eliminates the last problem you posed because if something goes wrong with the sat you just de-orbit it before you had planned and write it off.
If you fly through the beam or walk through it you would not know. Do you feel a slight warming when you put your hand on top of your wifi antenna?
There are problems with space-based solar and beaming energy, but none of your objections make the list.
The sat does not need to be in geostationary orbit and in fact a better solution is to have a constellation at lower orbits. This also eliminates the last problem you posed because if something goes wrong with the sat you just de-orbit it before you had planned and write it off.
If you fly through the beam or walk through it you would not know. Do you feel a slight warming when you put your hand on top of your wifi antenna?
There are problems with space-based solar and beaming energy, but none of your objections make the list.
The non-geostationary design in low-earth orbit is mentioned with not much detail in this article and would generate far less power for a particular receiving location since it only periodically receives power -- so there are various objections to that approach as well.
In the case of the geostationary energy being sent through the atmosphere to the receiver -- they mentioned 2000MW of power being delivered -- assuming you use the area of a house (as viewed from top down) as an area to compare against, by some rough calculations roughly 10KW would be impinging upon a house surface that is roughly 1500sqmeters -- so 10KW of microwave energy directed into a house area -- that is non-trivial, so I assume your comparison between wifi antenna's was in reference to the low earth orbit solution -- the geo stationary solution referenced in the article is very powerful and would be in a totally different class from the approx sub 1W range coming from your wifi antennas. So I would be worried to walk through it.
>in fact a better solution is to have a constellation at lower orbits
only that this turns the cost of something that is already very very expensive into something that is hideously ridiculously expensive.
only that this turns the cost of something that is already very very expensive into something that is hideously ridiculously expensive.
No it doesn’t. The major cost is not the satellite structure, it is getting up there. Low orbit costs significantly less.
> if you flew an airplane through that 30 sq km area what happens, or various wildlife like birds fly through that area?
30 square kilometers is 3e7 m^2. 2000 MW is 2e9 W. So you're looking at less than 70 W/m^2.
For comparison, the solar constant [1] is more than 1300 W/m^2.
So, no cooking.
Also, the receivers would be microwave antennas on poles, i.e. they wouldn't monopolize the land they stand on. There is concept art from the 70s showing cows grazing between/under them.
[1] https://en.wikipedia.org/wiki/Solar_constant
30 square kilometers is 3e7 m^2. 2000 MW is 2e9 W. So you're looking at less than 70 W/m^2.
For comparison, the solar constant [1] is more than 1300 W/m^2.
So, no cooking.
Also, the receivers would be microwave antennas on poles, i.e. they wouldn't monopolize the land they stand on. There is concept art from the 70s showing cows grazing between/under them.
[1] https://en.wikipedia.org/wiki/Solar_constant
> 70 W/m^2
For reference, according to wikipedia [1] the US federal limit on microwave oven emissions (outside of the enclosure, ie, what you would experience if you smushed your face against the glass while watching your oatmeal cook) is 50 W/m^2, which is "far below the exposure level currently considered to be harmful to human health".
[1] https://en.wikipedia.org/wiki/Microwave_oven#Direct_microwav...
For reference, according to wikipedia [1] the US federal limit on microwave oven emissions (outside of the enclosure, ie, what you would experience if you smushed your face against the glass while watching your oatmeal cook) is 50 W/m^2, which is "far below the exposure level currently considered to be harmful to human health".
[1] https://en.wikipedia.org/wiki/Microwave_oven#Direct_microwav...
30 sq km isn't even a lot less than the land you'd need for a simple terrestrial PV station of the same capacity. NREL said in 2012 that the total space needed for PV is 8 acres per MW, so 2000 MW would occupy 65 sq km.
Are you comparing peak power? Keep in mind that space-based solar can work around the clock, while ground-based hits peak power only around noon and does nothing at all at night, so it needs to (1) be complemented with something else for baseload and (2) be oversized by some multiple to deliver enough power through the day.
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"Many of the raw materials needed for a SSP system can be sourced from asteroids or the lunar surface and if these could be used to manufacture the SSP components in orbit it would cause the cost of the system to plummet. In fact, in-space manufacturing may be key to making SSP a cost-competitive energy resource."
This is mostly an excuse to spend money on space programs. It has to be cheaper than ground-based solar power with batteries, which is working and works better every year.
It's one of those ideas, like automotive battery swapping, which were a bet against batteries getting better.
This is mostly an excuse to spend money on space programs. It has to be cheaper than ground-based solar power with batteries, which is working and works better every year.
It's one of those ideas, like automotive battery swapping, which were a bet against batteries getting better.
The interesting thing about space-based solar power is that you do not need to direct the beam at the earth. You can also use it to beam energy to remote probes and robotic installations. If you want to mine asteroids you are better off beaming the energy from earth orbit than you are trying to capture solar on site. Sending the energy from earth makes it much easier to fix/replace the power generation satellite if your remote mission is going to depend on that for power generation.
Aiming a tight beam any significant distance would be tough though? I am sure you could hit the moon (not too far) but trying to push a solar sail or the PV on a probe in the outer solar system seems like a very small target (plus there are other bodies in between, sometimes...)
It is not easy, but the energy density of that beam will vastly exceed sunlight at any significant distance. If you are no longer concerned with getting the beamed energy through a wet atmosphere you can also use better frequencies (e.g. visible light lasers or even higher frequencies that might have better margins when it comes to conversion losses.)
The extra power density of the beam is only useful if you’re capturing a significant fraction of the beam at the far end, which implies both ends have big parabolic mirrors for whatever wavelength you’re using (because that’s the limiting factor in how tight you can focus photons), and if you’re doing that then you could skip the transmitter and point the receiver at the sun to greater effect — you’d need a 100m mirror on the transmitter to hit an Apollo-lander-sized receiver 1.3 light-seconds away — and if you’re concerned about different solar radiation flux at different points, you’re talking about beaming power over multiple light-minutes, main asteroid belt starting about 2 AU from the sun, about 8 light minutes from Earth at minimum.
The distance is also large enough you need to be very certain about what’s going on outside your light cone.
The distance is also large enough you need to be very certain about what’s going on outside your light cone.
Charlie Stross recently wrote a blog post about this: http://www.antipope.org/charlie/blog-static/2021/09/fossil-f...
He is a lot more optimistic than the average person in this comments section.
He is a lot more optimistic than the average person in this comments section.
From that post, it gets 4x the efficiency but loses 70% in transmission. Which basically cancel each other out.
So the only advantage is the 24x7 availability. Which is a big advantage, but I'm not sure if it's big enough.
So the only advantage is the 24x7 availability. Which is a big advantage, but I'm not sure if it's big enough.
It should be possible with investment in current tech to get transmission losses down to 30-40% or less, IMHO. There’s lot better power transistors, controls, and simulation to improve over the last experiments done decades ago. Some were done in the 1970’s. Incremental improvements do add up.
You could do antipodal HVDC for ~50% loss with the stuff currently on the market (3.5% loss per 1000km).
I do like one of the other suggestions to use this for Mars solar — Mars has a much bigger problem with dust blocking sunlight than Earth does — but I don’t see it being more than experimental here, at least not without a unified world government to remove political risks and a whole bunch of other tech that might make it redundant anyway.
I do like one of the other suggestions to use this for Mars solar — Mars has a much bigger problem with dust blocking sunlight than Earth does — but I don’t see it being more than experimental here, at least not without a unified world government to remove political risks and a whole bunch of other tech that might make it redundant anyway.
Mars would be interesting, along with powering space mining operations. Perhaps focused mirrors on the moon or in earth orbit to illuminate earth based solar panel arrays at night. I'd guess aluminum mirrors in space would stay reflective for many decades.
> I'd guess aluminum mirrors in space would stay reflective for many decades.
How long stuff lasts is an interesting point I has not considered. More UV, micro-meteors, even the question of what light pressure does to the orbits over a few years, given the large surface area to mass ratio. I don’t know how similar or different conditions are in the ISS orbit versus any other.
That aside, I think optical mirrors are going to be the least acceptable with regard to security/defence types, as that’s the easiest to be surreptitiously modified into a death ray, just because all the elements are physically smaller. With RF you can at least make it so any modifications are ridiculously obvious, even if you still have to care about malicious combination of multiple systems.
But on the Moon? Not only will we probably only need at most a handful, the fact that the Earth-Moon distance is much larger than most orbits considered for space-based solar power means even a maliciously retargeted combination of system would be much less of a threat.
How long stuff lasts is an interesting point I has not considered. More UV, micro-meteors, even the question of what light pressure does to the orbits over a few years, given the large surface area to mass ratio. I don’t know how similar or different conditions are in the ISS orbit versus any other.
That aside, I think optical mirrors are going to be the least acceptable with regard to security/defence types, as that’s the easiest to be surreptitiously modified into a death ray, just because all the elements are physically smaller. With RF you can at least make it so any modifications are ridiculously obvious, even if you still have to care about malicious combination of multiple systems.
But on the Moon? Not only will we probably only need at most a handful, the fact that the Earth-Moon distance is much larger than most orbits considered for space-based solar power means even a maliciously retargeted combination of system would be much less of a threat.
It can be used as light source for cities at night, or even as CO2-free heating system for big cities at winter. Just imagine environmental cost of heating of New-York.
It’s surprising but even that author turns up a much more reasonable return on investment than I expected. His calculations suggest it’s possible to repay the energy costs, including orbit, after only a few years.
Though as he points out there’s lots of elements which are still impractical. Though I wonder if it could be worthwhile given that covering the Sahara with solar panels would change the global climate (particularly Brazil’s) (1). Space based arrays might be a possible way to avoid that. Or perhaps provide a power source for remote areas. A starlink for power would be intriguing.
1: https://www.techtimes.com/articles/257268/20210221/sahara-de...
Though as he points out there’s lots of elements which are still impractical. Though I wonder if it could be worthwhile given that covering the Sahara with solar panels would change the global climate (particularly Brazil’s) (1). Space based arrays might be a possible way to avoid that. Or perhaps provide a power source for remote areas. A starlink for power would be intriguing.
1: https://www.techtimes.com/articles/257268/20210221/sahara-de...
Plants (even at their puny 2% efficiency) can utilize only a fraction of a full day's insolation; they are limited by other factors.
Thus, there is no need to put solar panels in faraway deserts. Putting them above other land uses -- parking lots, buildings, reservoirs, pastures, cropland -- nearer to use reduces transmission costs. Shading reservoirs, pastures and crops also reduces evaporation, thus saving water. Where water is a limiting factor, partial shade increases yield. Where water is not the limiting factor, reducing water use cuts salt fouling, and enables other uses for the water, including restoring natural habitat.
There is absolutely no shortage of land suitable for solar arrays. You mostly see them on dedicated land (besides roofs) just because that is still cheaper.
Thus, there is no need to put solar panels in faraway deserts. Putting them above other land uses -- parking lots, buildings, reservoirs, pastures, cropland -- nearer to use reduces transmission costs. Shading reservoirs, pastures and crops also reduces evaporation, thus saving water. Where water is a limiting factor, partial shade increases yield. Where water is not the limiting factor, reducing water use cuts salt fouling, and enables other uses for the water, including restoring natural habitat.
There is absolutely no shortage of land suitable for solar arrays. You mostly see them on dedicated land (besides roofs) just because that is still cheaper.
While that currently appears to be true, it may still turn out to be useful to have PV in a distant desert and connected by a global grid.
While batteries+overproduction is cost effective for overnight and even over-winter, we are still in the scaling up process for battery manufacture, and if that turns out to have a limit for whatever reason, solving the nighttime/winter problem can also be done with intercontinental HVDC[0]. And if batteries can do nighttime but not winter, those connections only need to be north-south not antipodal.
[0] At least in principal, I don’t know anything about the geological or political restrictions.
While batteries+overproduction is cost effective for overnight and even over-winter, we are still in the scaling up process for battery manufacture, and if that turns out to have a limit for whatever reason, solving the nighttime/winter problem can also be done with intercontinental HVDC[0]. And if batteries can do nighttime but not winter, those connections only need to be north-south not antipodal.
[0] At least in principal, I don’t know anything about the geological or political restrictions.
Battery cost is still plummeting. Iron/air tech is coming to market at 1/3 the cost of lithium, with no conceivable scaling limit. It is not clear whether other storage methods will end up even cheaper than wherever battery cost levels off. If it does.
But efficiency of power transmission technology has also radically improved, so that the chief downsides to distant generation are risk of failure of the transmission medium, and of political instability at the remote site or on the route. Anybody dependent on distant generation had better have multiple distant sources.
In practice, we will end up with both local generation and storage and long-distance HVDC backup, to accommodate different failures. Countries without trusted neighbors will need more storage.
But efficiency of power transmission technology has also radically improved, so that the chief downsides to distant generation are risk of failure of the transmission medium, and of political instability at the remote site or on the route. Anybody dependent on distant generation had better have multiple distant sources.
In practice, we will end up with both local generation and storage and long-distance HVDC backup, to accommodate different failures. Countries without trusted neighbors will need more storage.
That’s my expectation, but until we’ve deployed these in sufficient scale, I would hope we are not unwise enough to count our chickens before they’re hatched/put all our eggs in one basket.
> His calculations suggest it’s possible to repay the energy costs, including orbit, after only a few years.
No. No they don't. that's not what his conclusions are at all. How did you even get that?
He's comparing space-based vs. land, not space-based vs. nothing. His conclusion is that it's pointless to build solar power collectors in space for terrestrial power applications. In all cases, if you want power on earth, build the solar on earth.
No. No they don't. that's not what his conclusions are at all. How did you even get that?
He's comparing space-based vs. land, not space-based vs. nothing. His conclusion is that it's pointless to build solar power collectors in space for terrestrial power applications. In all cases, if you want power on earth, build the solar on earth.
> Add the embodied energy of the other components in space and on the ground, and I could easily believe we get to a year payback—now bringing the total (manufacture plus launch) to two years and an EROEI around 10:1.
> If my 100× light-weighting proves to be unrealistic, and we can only realize a factor of ten improvement over our rooftop panels, the solar panel launch cost climbs to three years, so that adding other components results in perhaps a 4:1 EROEI.
> In the end, the EROEI is not as prohibitive as I imagined: it’s not a net energy drain as I might have feared. But it’s not obviously better than conventional solar either.
His overall conclusion may reach that conclusion, but his EROI give SPS a net 10:1 to 4:1 energy returns even in his worse case. So regardless if its cost competitive to ground based arrays or not, it might have uses and would likely result in net energy gain vs input (including materials).
His overall conclusion may reach that conclusion, but his EROI give SPS a net 10:1 to 4:1 energy returns even in his worse case. So regardless if its cost competitive to ground based arrays or not, it might have uses and would likely result in net energy gain vs input (including materials).
It's like saying I could drive 80 miles each way to a gas station despite there being dozens of options within 5 miles.
I get more energy than I spend, but it's never worth it.
Also the gas there is extremely expensive.
I get more energy than I spend, but it's never worth it.
Also the gas there is extremely expensive.
Even in your example there are scenarios it could be worthwhile. What if it’s gas produced in-country and its used as a military fill station? Particularly if it’s always available despite foreign political events. For personal usage maybe it’ll never be worth it, but perhaps it’s worthwhile for other use cases. Solar + batteries might not work if you can’t buy/procur enough batteries, especially for Arctic regions say where days are short.
Or perhaps it’ll become possible to use for recharging electric airplanes in-flight. In that case the ability to “beam” worldwide might offset the cost of ground based grid of towers or ocean barges, etc.
To be clear, I think it’s very unlikely, just not infeasible. Particularly if antennae tech keeps improving.
Or perhaps it’ll become possible to use for recharging electric airplanes in-flight. In that case the ability to “beam” worldwide might offset the cost of ground based grid of towers or ocean barges, etc.
To be clear, I think it’s very unlikely, just not infeasible. Particularly if antennae tech keeps improving.
> What if it’s gas produced in-country and its used as a military fill station? Particularly if it’s always available despite foreign political events.
Except local solar requires fewer resources of every kind than satellite solar. You're more likely in every way to get cut off from the space version.
> Or perhaps it’ll become possible to use for recharging electric airplanes in-flight. In that case the ability to “beam” worldwide might offset the cost of ground based grid of towers or ocean barges, etc.
That would be cool. But it's a very different problem from grid power. I don't think it counts as a reason to beam dedicated space power to ground stations.
Except local solar requires fewer resources of every kind than satellite solar. You're more likely in every way to get cut off from the space version.
> Or perhaps it’ll become possible to use for recharging electric airplanes in-flight. In that case the ability to “beam” worldwide might offset the cost of ground based grid of towers or ocean barges, etc.
That would be cool. But it's a very different problem from grid power. I don't think it counts as a reason to beam dedicated space power to ground stations.
No thank you - I've played Sim City.
(https://simcity.fandom.com/wiki/Microwave_(disaster))
(https://simcity.fandom.com/wiki/Microwave_(disaster))
This is what I thought of first as well.
I remember reading about this solar power beam concept when I was a kid in one children magazine. The article mentioned Peter Glaser as the author of the idea and it had these gorgeous illustrations. After some digging I managed to find it in the depths of the internet
https://imgur.com/a/1MPWd62 https://imgur.com/a/sF3MzSj
I don't like this particular writeup, the use of 'baseload' makes me think this is someone who doesn't understand energy markets trying to use it as an excuse for funding rockets.
But I do wonder if there might be better applications if you think outside the box.
Can standard PV installations be the receiver? Could this act as a complement to ground based arrays by using them at night or during winter by supplementing natural light? How does the math look for wavelengths that PV can capture?
The ability to inject extra power into the grid as required might make a small number of these cost effective for the whole planet, rather than as a bulk energy source.
Is there any way of extracting CO2 from the atmosphere or breaking down methane faster that could be done from low earth orbit with cheap enough energy?
Could these supplement the energy requirements of planes, boats or trains by beaming energy at moving targets? (Feels like the receiver would need to be too large for this to work well).
Is there any use for heating clouds? Can this cause rain to control weather? As well as the standard weather control thing, that could also help with terrestrial solar production.
But I do wonder if there might be better applications if you think outside the box.
Can standard PV installations be the receiver? Could this act as a complement to ground based arrays by using them at night or during winter by supplementing natural light? How does the math look for wavelengths that PV can capture?
The ability to inject extra power into the grid as required might make a small number of these cost effective for the whole planet, rather than as a bulk energy source.
Is there any way of extracting CO2 from the atmosphere or breaking down methane faster that could be done from low earth orbit with cheap enough energy?
Could these supplement the energy requirements of planes, boats or trains by beaming energy at moving targets? (Feels like the receiver would need to be too large for this to work well).
Is there any use for heating clouds? Can this cause rain to control weather? As well as the standard weather control thing, that could also help with terrestrial solar production.
> Can standard PV installations be the receiver?
space based mirrors could be really cheap and light. Think of a big mylar sheet held flat with this[1] mechanism.
When you double the brightness of light on a solar panel, you more than double the power output, so using a series of space based mirrors could really increase the return-on-investment of on-ground solar panels.
Probably not very wildlife friendly... Perhaps best to do it in a desert.
[1]: https://www.youtube.com/watch?v=9iTLkKfip4o
space based mirrors could be really cheap and light. Think of a big mylar sheet held flat with this[1] mechanism.
When you double the brightness of light on a solar panel, you more than double the power output, so using a series of space based mirrors could really increase the return-on-investment of on-ground solar panels.
Probably not very wildlife friendly... Perhaps best to do it in a desert.
[1]: https://www.youtube.com/watch?v=9iTLkKfip4o
While Elon Musk is in the position that he could implement this idea, he thinks it's "the stupidest thing ever". [0]
[0] https://www.youtube.com/watch?v=9YZVAMh8b0s
[0] https://www.youtube.com/watch?v=9YZVAMh8b0s
Pretty damning considering some of his recent ideas.
Excellent link!
Elon Musk and stupid - Peaches and Cream
Elon Musk is in dire need of huge and profitable space-based businesses to justify his big investment in Starship, which is way overkill for any existing space business. And he is incredibly motivated to solve climate issues and big into solar power specifically. And he has repeatedly pursued far-fetched pie-in-the-sky business ideas that are straight out of sci-fi. This business would be perfect for him in about ten different ways, so the fact that he's not doing it means to me that he is completely convinced that it is absolutely impossible to do profitably with current or near-future technology.
That's.. a good point. Reminds me of the moonlanding counterfactual: if the USA did not land on the moon, don't you think the Soviet's would've said something about it? Or was the cold-war fabricated as well.
I do not think the moonlanding was faked and I really like that argument but still I do wonder what were the real level of intel (and level of confidence they had in that Intel) each of the two world powers had on each other at the time when the USSR existed. Also it could have happened that the USSR decide to propagate that the moon landing was fake for propaganda's purposes.
Apparently, skepticism of the moon landing having happened is much more prevalent in Russia than in the US.
We need large scale coherent perfect absorbers [0] before we can do long distance power beaming. Other than that with a solar pumped laser (spread out over many m^2 on the ground to reduce the death-ray-ness) you could get decent efficiency.
[0] basically a backwards laser. https://en.m.wikipedia.org/wiki/Coherent_perfect_absorber
[0] basically a backwards laser. https://en.m.wikipedia.org/wiki/Coherent_perfect_absorber
Space-based lasers might eventually be a good way to power long distance aircraft.
Approach for energy comparison of solar travel and orbital launches:
https://en.wikipedia.org/wiki/Delta-v_budget
What is the effect of pumping more energy into the environment? Would that just mean global warming via a different method?
Maybe if we ever find a way to manufacture continuous strands of nanotubes, we could create both space elevators as well as wired LEO solar power.
Tongue-in-cheek question: If it's in geostationary orbit, couldn't we just run a cable down (/up)?
How is the electrical power transmitted to earth? Radio wawes? Couldn't that produce interferences?
This will never happen. Period.
and eventually end up with a Dyson Sphere around earth. Doesn't sound like a great idea to redirect earth bound heat for electricity
That sounds like a selling point to me - obviously geoengineering is controversial, but if you could overcome that resistance, you could slow warming and also generate power, win-win.
Just to construct some massive structure in space is a monumental challenge. Every ton of solar panels or support structure needs some bus to get it to the right orbit and maneuver it in place. Even if you assume fully automated construction you need buses for all the construction robots and tankers to refuel them. Any collisions could scrap the whole project by making a debris cloud in the same orbital plane as the relatively fragile solar panels.
That all ignores the sourcing of raw materials, finished components, fuel, and buses to flit everything around. The "easy" answer is "use in-situ materials". In-space mining, refining, and fabrication are all entirely unsolved problems. Even the cheapest vapor ware SpaceX heavy lift rocket isn't cheap enough to build a space based solar plant with components from Earth.
The technical difficulty and cost would be ridiculous compared to just building ground based renewables. Ones of billions of dollars will get you gigawatts worth of off-shore wind power or ground based solar.
Unless you have access to literal magic there's no situation where space based solar ends up more efficient or cheaper than ground based renewables. The capital expense is literally and figuratively astronomical.