3 ms·

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

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.

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.