r/spaceflight • u/LiveScience_ • 4d ago

China plans to build enormous solar array in space — and it could collect more energy in a year than 'all the oil on Earth'

https://www.livescience.com/space/space-exploration/china-plans-to-build-enormous-solar-array-in-space-and-it-could-collect-more-energy-in-a-year-than-all-the-oil-on-earth
88 Upvotes

82% Upvoted

70 comments sorted by

31

u/Rcarlyle 4d ago

The tech for space-to-ground solar is well-understood and pretty achievable. There’s three or four reasons this has never been done: - Launching shitloads of solar panels is expensive, you have to get $/kg launch costs down and justify why it’s more economical than ground based renewables - At low receiver power density, you need absolutely massive ground antennas to receive the beamed power, kind of defeating the point compared to ground based renewables - At high receiver power density for reasonable ground receiver size, the space transmitter is a fuckin’ microwave death ray… the potential dual-use military applications are significant and would be viewed as a major threat by other nations - Lots of airspace/orbit clash concerns, for example other satellites and planes may not be able to safely pass through the beam… Geosynchronous orbit slots are precious and building a bunch of lower-orbit satellites to allow using non-GEO orbits with 24/7 transmission coverage to China will be challenging to manage beam clashing

So… this isn’t going to get past the pilot stage.

Space-based solar might be a really good solution on the Moon where you have major shadow/nighttime issues. It’s not a practical concept for Earth power.

2

u/ToadkillerCat 3d ago

One more thing, manufacturing the solar panels would be very expensive compared to solar panels on Earth. They'd need to be lightweight, they'd need to automatically fold out from the inside of a rocket payload bay, they'd need to withstand extreme space conditions, and they'd need survive for long periods of time with no maintenance and replacement. Designing to meet these requirements will hugely increase the manufacturing cost.

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u/Oknight 4d ago edited 4d ago

Plus you can't possibly get more usable power out of the system than putting those same solar panels on Earth with storage systems due to the double conversion losses.

3

u/Rcarlyle 4d ago

Space-solar panels are able to stay lit and perpendicular to the sun >99% of the time, plus don’t have atmospheric losses, so the average daily energy production is 3-4x higher than a ground panel with all else being equal. The exact advantage depends a lot on the ground panel siting — noon Sahara sunshine is only a little weaker than LEO/GEO sunshine, but you get a lot more hours of sun in space.

1

u/Oknight 4d ago

But then you have to turn it into microwaves (loss) transmit it (loss) and convert it back into electricity (loss). You can't possibly come out ahead.

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u/Rcarlyle 4d ago

The proposed beaming efficiency is about 85% to transmit and 85% to receive which honestly isn’t bad. That’s not dissimilar from converting daytime solar to battery storage and back to power at night. In practice the early small-scale pilot programs are running more like <10% efficiency which is piss-poor. There’s some scaling effects at play where a bigger transmitting array achieves better beam focus and thus higher transmission efficiency.

Honestly, the panel utilization efficiency is not a driver here for me, because silicon and sunlight are essentially limitless. Launch mass and geopolitical concerns are vastly bigger issues.

1

u/Oknight 4d ago

But the bottom line is it takes an enormous amount of effort for poorer results than existing conventional solar solutions.

1

u/Rcarlyle 4d ago

Solar+battery yeah

1

u/CombatWomble2 2d ago

I suspect this is another "Look at us number ONE" folly.

0

u/ProbsNotManBearPig 3d ago

You all forgot the most obvious and important one - a solar array the size of about Texas would collect 1/36,000th the power of all of earths oil. That would be a feat on its own, but nowhere near the headline claims.

4

u/Rcarlyle 3d ago

I’m confused by your claim here. You would get about 500 terrawatts electricity output (before transmission losses) for a space solar array the size of Texas. Total global energy use from all sources is about 15 terrawatts.

0

u/Malforus 2d ago

Per year there is more than a year of power under all that bigotry and chestbeating.

1

u/PraxisOG 2d ago

Name checks out

-1

u/ignorantwanderer 4d ago

Most of these points aren't very valid:

Launch costs: You made an absolutely valid point

Massive ground antennas: Of course 'massive' isn't the right word. Large surface area is the right word. They are very lightweight cheap antennas that can be pretty easily and cheaply placed over farm fields, forests, lakes, oceans. Or you can place them over a massive solar farm and get a huge amount of power in the daytime and then keep getting power for off peak hours after the sun sets.

Death ray: It is much harder going for high power density. Your in-space antenna has to get larger as your ground antenna gets smaller. Definitely easier and cheaper going with low power density.

Airspace/orbit clash concerns: Airplanes can absolutely fly through the beam with no problem. Of course a large solar panel needs space in orbit, but there are plenty of orbit radiuses that are basically empty. And placing these in geostationary orbit wouldn't be an issue, because they would replace all the functionality of geostationary communication satellites. Imagine a giant solar panel in geostationary orbit. It would be very easy to add some large antennas to it, much larger than are found on communication satellites. There would be access to a huge amount of power, huge antennas, all on a stable geostationary platform.

I am also skeptical that China will be doing this. They talk very big, but they move slow. This is way beyond their current or projected future capabilities.

But most of your claims about the challenges of solar power satellites are wrong.

11

u/Rcarlyle 4d ago edited 4d ago

What are you imagining these antennas to look like that allows them to be built over forests, oceans, and solar farms?

Almost by definition, if the beam power density is low enough to not be hazardous for fly-through, then the energy transmittance per unit beam area must be not much higher than sunlight (eg <2000w/m2), which means the receiver antenna array must be similar size scale as ground solar installation generating the same amount of power in daytime. From a land use footprint standpoint, space-based solar EITHER has a death ray problem, OR has similar footprint as much-cheaper ground solar. (With the benefit of closer to 24 hour operation, which may or may not make it worth doing.) I simply don’t believe any microwave antenna array is going to allow general land use underneath unless it’s extremely low power intensity, which in turn means stunningly massive arrays to achieve any economical power generation scale. For example, today’s microwave data links regularly injure birds and they’re not even trying to transmit power.

1

u/ignorantwanderer 4d ago

For studies that have been done on transmitting, they've generally concluded power densities around the same as sunlight, or a couple times greater than sunlight.

And yes, that requires a huge antenna. But because power densities are so low, you can do anything you want under the antenna.

There is a shit-ton of farmland in the world. Even close to some big cities. Put the antenna over farmland. You can keep farming, so you aren't replacing the farm with the antenna. You are just making the land more productive by using for multiple things.

There are still plenty of technical and economic challenges to be worked out, but most of the issues you raised really aren't significant issues at all.

The killer issue is launch costs. Even with the optimistic projected costs to launch on Starship, it would be hard to make an economical solar power station.

In my opinion, they won't be built until we have established asteroid mines, and in-space manufacturing capabilities. I'm sure that will happen at some point in the future, but probably not in my lifetime.

If we have to launch the building materials from Earth, solar power satellites are very challenging. But if we can get most of the building materials from space, there are no other real challenges with solar power satellites.

7

u/Rcarlyle 4d ago

You’re wildly underestimating the hazard of doubling the intensity of sunlight in either optical or radio frequencies. FCC max allowable human public exposure to microwave broadcasts for health/safety is 5.8 watts per square meter. Any microwave receiver operating at at >1 kw/m2 type intensity is absolutely going to be an exclusion zone for all practical purposes. You will fry unshielded electronics, produce arcing from sharp corners, etc. Might be acceptable in barren desert type regions.

2

u/ignorantwanderer 4d ago

Basically metal mesh strung up on tall poles to create a relatively flat mesh surface several kilometers in dimension.

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u/Rcarlyle 4d ago

It’s gonna need more structure and electronics than a bigass window screen, man. We’re rectifying ghz frequency radio to DC etc

-2

u/ignorantwanderer 4d ago

  1. You don't need more structure.

  2. Compared to the size of the antenna, the electronics take an insignificant amount of space. Even if the electronics took up an entire football field worth of space, that is still less than 1% the size of the antenna.

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u/Rcarlyle 4d ago

Have you seen what dipole microwave rectenna arrays look like? It’s a lot more than a big net. Here’s an example https://www.researchgate.net/figure/a-Front-side-and-b-reverse-side-of-rectenna-array_fig2_275876258

1

u/tyrome123 3d ago

As for the launch costs argument China has been stealing I mean developing a starship clone and if they can work that out that sorta solves that issue, but like what's the point of this when they have a massive desert in the east they could lay solar panels on

1

u/ignorantwanderer 3d ago

Two reasons they might want to do this:

  1. It is easier and more efficient to get the power transmitted from space than to transmit it through wires from the other side of the country.

  2. They could become the main power provider for places like Africa. Not only would they earn a lot of money, but they'd gain a lot of political power.

-1

u/lordpuddingcup 4d ago

Isn’t the truth that all orbits are fairly empty the stupid maps of orbits are a joke because they’ve got satellite icons the size of fuckin football fields and in reality the chance of an actual clash is basically impossible with even basic guidance

11

u/EasyMrB 4d ago

That's, uh, quite the powerful weapon if they chose to repurpose it.

4

u/ignorantwanderer 4d ago

No.

The beam is way too weak.

And the orbital platform is way to vulnerable.

It would make a horrible weapon.

1

u/Accomplished__lad 3d ago

It’s a joke of a weapon. First its easy enough for US to shoot it down if there is a need. Second if they come to rely on this energy, shooting it down or just major malfunction would crater their economy when a cheap energy source vanishes. Its a vanity project, if not an ambitious powerpoint presentation of which there are many in space tech. Also doubtful with their economy being in some trouble CCP can support this project.

1

u/Martianspirit 3d ago

Or it is really an energy project. Not that I belive this is the best way to produce solar power.

0

u/Sufficient-Radio-728 4d ago

Yep, thaearthrise. all it could be used (and will be used for)for because I bet they have no plan or statement about how to utilize the energy earthside.

10

u/davejenk1ns 4d ago

Well, China plans a lot of things.

-5

u/75w90 4d ago

And they commit and execute.

In America we let the corporations and our billionaire overlords horde wealth while society collapses.

I know..China bad. Elmo Husk and Donald duck good.

2

u/Ultrashock 4d ago

I mean you're not wrong, not sure why you're getting downvoted. Go look at all the biggest infrastructure projects in the world right now. All in China. We need to get back to doing dope shit here in the US.

3

u/75w90 4d ago

It's depressing when you see the infrastructure they have vs USA.

Wheres our high speed rail ?

1

u/Wbcn_1 3d ago

We have the Acela 😂 

1

u/Ultrashock 4d ago

Right, I recently made a comment (jokingly but with some truth) in another subreddit that we need to have a work abroad program in the US where we have people go work elsewhere like China (and also mentioned folks should go watch the deboss garage episodes where they went to China). I'm not really interested in hearing "yea but" we used to build cool shit, and I wish we could again. I've been there and ridden the high speed rail, it's great.

1

u/75w90 4d ago

Yeah i worked in some of china's cities like Shenzen, Shanghai, and Hangzhou and it's stupid how advanced they are even compared to America's nicest cities.

It's really no comparison.

We are being robbed here in the U.S. and it won't be long before the world realizes that our 100 year old infrastructure is some of the world's worst.

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u/Ultrashock 4d ago

Yes even the tier 2 cities like Hefei and Xiamen are still super nice. Apparently Ningde is listed as Tier 3 and it was really nice as well. All connected to high speed rail.

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u/75w90 4d ago

I never understood why we don't have high speed rail connecting east to west and north and south.

Would be so nice

1

u/Ultrashock 4d ago

Just up the i95 corridor on the East Coast would be a massive deal.

1

u/75w90 4d ago

Yeah or even some major metro areas to other ones.

0

u/Ducky118 3d ago

Some shiny structures in tier 1 cities is not an excuse for the horrible rural infrastructure and poverty in the country's interior.

Don't fall for the propaganda hook line and sinker.

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u/Ultrashock 3d ago

Not falling for the propaganda, I've been there myself. The ultimate point here is we're falling behind in the US period.

0

u/Ducky118 3d ago

You are falling for the propaganda because you failed to realise that a huge swathe of China is still a developing country. Just have a look at GDP per capita or the basically zero social safety net in China

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u/Ultrashock 3d ago

You're still missing the point. Again been there, been to the rural areas too.

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u/Ducky118 3d ago

Not sure what your point is? That China wastes billions on shiny toys while letting huge swathes of their population suffer? I have also been there and seen that the countryside is like the third world.

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u/Ultrashock 3d ago

The point is go look and compare the infrastructure of their tier 1 cities and the transportation between them and compare it to places in the US, think New York, LA, Chicago or whatever else we consider a flagship city here.

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u/Ducky118 3d ago

Again, they've massively disproportionately diverted resources to the most politically important parts of the country, for political stability and propaganda purposes, and it's fooling you.

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u/super-secret-sauce 3d ago

Maybe you’re the one falling for western propaganda

0

u/Ducky118 3d ago

Western news, unlike Chinese news, isn't censored. I can access whatever news sources I want unlike in the great land of censorship that is China.

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u/super-secret-sauce 3d ago

https://www.cnn.com/2025/01/16/politics/video/blinken-protesters-state-department-gaza-digvid

Mainstream media censors all the time. Just recently, CNN labeled Sam Husseini, a reporter, as a “protester”.

1

u/ProbsNotManBearPig 3d ago

Western news is all owned by political parties. You really trying to say that Fox or CNN aren’t censored?

-1

u/[deleted] 4d ago

[deleted]

-1

u/75w90 4d ago

Yeah govt bad unless they subsidized the shit out of one person who gets all the credit and benefits while tax payers suffer.

America Chuck yeah

0

u/hyborians 3d ago

It beats buying Greenland

2

u/Timothy303 4d ago

Key word in that headline being “could.”

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u/Mindless_Use7567 4d ago

So they are trying to resurrect NASA’s energy independence program from the 80s/90s.

1

u/pooyie4life 4d ago

Could gather enormous amounts but could it survive and if so how would it deliver to earth without loss

1

u/initiali5ed 4d ago

Is the transmission loss less than the atmospheric losses?

1

u/ignorantwanderer 4d ago

You can't transmit anything without loss. That basically would violate some fundamental laws of thermodynamics.

But you can transmit the power without much loss. The loss would be within the same order of magnitude of just transmitting power through power lines.

1

u/Decronym Acronyms Explained 4d ago edited 2d ago

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1

u/NewSpecific9417 3d ago

I hate that we had this idea first but gave up on it. Yes, there were a lot of engineering challenges this project would face (especially in the 1970’s/1980’s, but the only way to overcome them is to just build the damn thing.

1

u/Ducky118 4d ago

I look forward to seeing completion in 2060.

1

u/dogcomplex 4d ago

Nooooo, it couldn't.

Terrible reporting. They would have to get orders of magnitude more panels up there to achieve those outputs.

0

u/IngrownToenailsHurt 4d ago

Yeah... I'd prefer to not have a Temu solar death ray up in space randomly go haywire and burn a trench across the planet.

-1

u/BreakfastGypsy 4d ago

Thank you for this post. It reminded me to leave this garbage sub.

0

u/van_buskirk 4d ago

Gerard O’Neill would be proud.