5 ms·

OP suggests that land costs will soon dominate the equation. So no mention of orbital solar plants? Yes, somebody years ago published a study that said, Unecon

OP suggests that land costs will soon dominate the equation. So no mention of orbital solar plants? Yes, somebody years ago published a study that said, Uneconomical! because lift costs, panel cost, transmission inefficiencies. All of those are now drastically changed, by orders of magnitude. It is not a matter of IF orbital solar is economical, but WHEN.

sharemywin 2y ago
doesn't orbital solar also deflect sun so wouldn't it cool the earth at scale?
- adammarples 2y ago
  Teeny tiny scale
- noSyncCloud 2y ago
  The sunlight that hits the reflectors would never have hit the Earth anyway.
smeeth 2y ago
Related startup: Reflect Orbital plans to put mirrors in space so that light can be reflected back onto ground-based panels at night. A base assumption is often that orbital solar requires a panel in space, but even that might not be the case. https://www.reflectorbital.com/ https://www.reflectorbital.com/
0cf8612b2e1e 2y ago
I would need to see some supporting napkin math on how that makes financial sense. Something on the ground, accessible by Joe the handyman is always going to be cheaper than anything launched into space. To balance that out is going to require some huge win. Availability, efficiency, etc. Solar input in orbit is higher than what is received at ground, but similar order of magnitude. I am not sure there are real world designs for beaming power 100km from space, but you are going to take some amount of loss in transforming the power to a transmissible form, beaming it through the atmosphere, and reassembling it on the ground. Unless you have a pin point death beam, the power is going to be transmitted to a relatively large area, requiring a large amount of land to receive it. Why not just build solar panels there? Seems far easier to overbuild panels on the ground + batteries.
- thfuran 2y ago
  >Solar input in orbit is higher than what is received at ground, but similar order of magnitude. On a sunny day, it's only something like 30% brighter above the atmosphere IIRC. I guess you beat cloud cover (assuming you can deliver it to ground through the clouds efficienly), but I agree it doesn't seem worth it.
  - pfdietz 2y ago
    The big advantage is the PV in space doesn't experience night (aside from very rare eclipses by Earth in geostationary orbit, which happens for a short period twice a year). If we had laser power beaming it might make sense to put large PV installations around the Earth-Sun L2 point, so the power could be beamed to collectors on Earth's night side. Each beam would serve a series of collectors as the Earth rotated. The market in the Pacific would quickly be saturated, I imagine.
  - JoeAltmaier 2y ago
    9X brighter
    - thfuran 2y ago
      Per Wikipedia, solar irradiance at 1 the top of the atmosphere is about 1,360 W/m^2, at at the surface on a clear day with the sun at its zenith is 1,050 W/m^2.
      - JoeAltmaier 2y ago
        Solar flux is half gone by the time it gets to the ground (reflection, cloud absorption) Witness the clause 'at its zenith'. That means, too much atmosphere is in the way the rest of the day to matter. In space, the sun is always at its zenith, if you look the right direction. Further, you have the opportunity to convert all of it, rather than the 50% that reaches the ground.
pulvinar 2y ago
The middle of a large desert is effectively free land, and perfect for solar. I don't see how space could ever be more economical in any respect. If beaming energy gets cheaper than transmission lines, we can beam it point-to-point on the earth too.
- JoeAltmaier 2y ago
  Read more. Atmosphere and night tank ground-based solar by maybe 80% of what's possible. And, sand is a terrible thing to operate any efficient optics around. No, the desert is a fairly bad choice. Sure, it's kinda bright there, part of the day. That's about the only thing on the plus side.
  - pulvinar 2y ago
    The vast majority of telescopes are ground-based even though space is optimal for seeing, because the economics favor the ground by a wide margin. Same with solar: if you get 3 times the light in space per cell but it costs 100+ times as much to install and use, it's pointless. And there's more than enough desert that isn't sand dunes. Even the Sahara is only 25% dunes.
ianburrell 2y ago
Cheap solar panels mean that orbital solar will never be economical. Orbital solar made sense back when solar panels were super expensive so made sense to use them continuously. Solar panels are so cheap now that people are setting them on the ground. 400W solar panel costs $200 and weighs 40 lbs. If Starship gets down to $100/lb, that is $4000 to put a panel in space. There are thin film panel that weight way less but cost more that would improve the launch cost but still be expensive. That means that will be cheaperp to have many panels on Earth and have enough left for storage.
- JoeAltmaier 2y ago
  Land; emminent domain; night all work in favor of orbital solar. Every number you mention is going in the right direction to favor orbital. Don't imagine space-solar will look (or weigh) anything at all like a terrestrial model.
ZeroGravitas 2y ago
You're suggesting land costs are the key here, but orbital solar beaming energy down as microwaves to earth need giant antenneas similar in land area to a solar farm as recievers. So there is no land advantage to offset the other costs.
- JoeAltmaier 2y ago
  Um. except the radiance is whatever you like. So if it's 10X normal solar watts/sqmeter then you need 1/10th the land.

sharemywin 2y ago

doesn't orbital solar also deflect sun so wouldn't it cool the earth at scale?

adammarples 2y ago
Teeny tiny scale
noSyncCloud 2y ago
The sunlight that hits the reflectors would never have hit the Earth anyway.

smeeth 2y ago

Related startup: Reflect Orbital plans to put mirrors in space so that light can be reflected back onto ground-based panels at night. A base assumption is often that orbital solar requires a panel in space, but even that might not be the case. https://www.reflectorbital.com/ https://www.reflectorbital.com/

0cf8612b2e1e 2y ago

I would need to see some supporting napkin math on how that makes financial sense. Something on the ground, accessible by Joe the handyman is always going to be cheaper than anything launched into space. To balance that out is going to require some huge win. Availability, efficiency, etc. Solar input in orbit is higher than what is received at ground, but similar order of magnitude. I am not sure there are real world designs for beaming power 100km from space, but you are going to take some amount of loss in transforming the power to a transmissible form, beaming it through the atmosphere, and reassembling it on the ground. Unless you have a pin point death beam, the power is going to be transmitted to a relatively large area, requiring a large amount of land to receive it. Why not just build solar panels there? Seems far easier to overbuild panels on the ground + batteries.

thfuran 2y ago
>Solar input in orbit is higher than what is received at ground, but similar order of magnitude. On a sunny day, it's only something like 30% brighter above the atmosphere IIRC. I guess you beat cloud cover (assuming you can deliver it to ground through the clouds efficienly), but I agree it doesn't seem worth it.
- pfdietz 2y ago
  The big advantage is the PV in space doesn't experience night (aside from very rare eclipses by Earth in geostationary orbit, which happens for a short period twice a year). If we had laser power beaming it might make sense to put large PV installations around the Earth-Sun L2 point, so the power could be beamed to collectors on Earth's night side. Each beam would serve a series of collectors as the Earth rotated. The market in the Pacific would quickly be saturated, I imagine.
- JoeAltmaier 2y ago
  9X brighter
  - thfuran 2y ago
    Per Wikipedia, solar irradiance at 1 the top of the atmosphere is about 1,360 W/m^2, at at the surface on a clear day with the sun at its zenith is 1,050 W/m^2.
    - JoeAltmaier 2y ago
      Solar flux is half gone by the time it gets to the ground (reflection, cloud absorption) Witness the clause 'at its zenith'. That means, too much atmosphere is in the way the rest of the day to matter. In space, the sun is always at its zenith, if you look the right direction. Further, you have the opportunity to convert all of it, rather than the 50% that reaches the ground.

pulvinar 2y ago

The middle of a large desert is effectively free land, and perfect for solar. I don't see how space could ever be more economical in any respect. If beaming energy gets cheaper than transmission lines, we can beam it point-to-point on the earth too.

JoeAltmaier 2y ago
Read more. Atmosphere and night tank ground-based solar by maybe 80% of what's possible. And, sand is a terrible thing to operate any efficient optics around. No, the desert is a fairly bad choice. Sure, it's kinda bright there, part of the day. That's about the only thing on the plus side.
- pulvinar 2y ago
  The vast majority of telescopes are ground-based even though space is optimal for seeing, because the economics favor the ground by a wide margin. Same with solar: if you get 3 times the light in space per cell but it costs 100+ times as much to install and use, it's pointless. And there's more than enough desert that isn't sand dunes. Even the Sahara is only 25% dunes.

ianburrell 2y ago

Cheap solar panels mean that orbital solar will never be economical. Orbital solar made sense back when solar panels were super expensive so made sense to use them continuously. Solar panels are so cheap now that people are setting them on the ground. 400W solar panel costs $200 and weighs 40 lbs. If Starship gets down to $100/lb, that is $4000 to put a panel in space. There are thin film panel that weight way less but cost more that would improve the launch cost but still be expensive. That means that will be cheaperp to have many panels on Earth and have enough left for storage.

JoeAltmaier 2y ago
Land; emminent domain; night all work in favor of orbital solar. Every number you mention is going in the right direction to favor orbital. Don't imagine space-solar will look (or weigh) anything at all like a terrestrial model.

ZeroGravitas 2y ago

You're suggesting land costs are the key here, but orbital solar beaming energy down as microwaves to earth need giant antenneas similar in land area to a solar farm as recievers. So there is no land advantage to offset the other costs.

JoeAltmaier 2y ago
Um. except the radiance is whatever you like. So if it's 10X normal solar watts/sqmeter then you need 1/10th the land.