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Real estate already generating revenue that may have solar added without reducing that revenue is not expensive. It has, instead, negative cost. Solar panels d

by ncmncm 4y ago

Real estate already generating revenue that may have solar added without reducing that revenue is not expensive. It has, instead, negative cost. Solar panels do not need to be "near major metropolitan centers". Modern transmission lines move power efficiently, silently, and reliably. It would be impressive for your orbital panels to get out 4x as much energy as the light they intercept carries, but getting a patent on your perpetual-motion apparatus might be difficult. Maybe do some elementary cost analysis. All the numbers are easy to find. Don't forget to figure in conversion loss from electric power on orbit to laser light emitted, losses scattering in the atmosphere, and conversion again from laser light received to electricity on the ground. You would better loft many-square-km aluminized-mylar mirrors to reflect sunlight to solar farms on the ground. Keeping them pointing the right direction would be tricky.

JoeAltmaier 4y ago
That's so far a pipe dream, dual-purpose 'negative cost'. Also transmission lines need right-of-way and are not free. Solar flux outside the atmosphere is 9X sea level. Go ahead, look it up. Then there's the periodic eclipse called 'night' that doubles orbital efficiency again. Look that up too. Conversion losses of 20% seem normal? Both in orbit and on the ground. Which halves what you collect, well within the budget of 20X reducing it to around 10X.
- ncmncm 4y ago
  Solar flux outside the atmosphere is not, in fact, 9x sea level. You can cook the numbers by keeping the orbital panel square on to the sun, while the ground-mounted panel rotates through the day and overnight. But you don't get to count nighttime twice. Conversion losses of only 20% from electric to laser, and again from laser to electric again, would be miraculous. 20% scattering loss in clear weather would be unsurprising. 90% loss, total, would be admirable, not counting the original 60%+ loss off the top. So, even with 9x, and neglecting huge launch cost you still come out behind.
  - JoeAltmaier 4y ago
    I looked it up. So about 75% of solar radiation reaches the ground. In the continental US, factoring in angle of the sun, average weather, night that comes to about 4-5KWh per day In orbit you would have just 1.37KW X 24 hours (no weather, angle issues) which comes to about 33KWh per day. So that's 8-9X the collected energy per square meter in orbit vs ground level. These folks https://www.allaboutcircuits.com/news/wireless-power-transmission-of-solar-energy-from-space/ https://www.allaboutcircuits.com/news/wireless-power-transmi... estimate 89% efficiency from orbit to ground. So we're then at around 30KWh effective. What am I missing?
    - Schroedingersat 4y ago
      > What am I missing? So many things. The massive clear area around your receiver. Scattering induced by weather means you still don't have 100% capacity factor. With only radiative cooling available, cooling will take up as much space as the panels and make everything heavier. The atmosphere doesn't absorb light uniformly. Maintenance. You're comparing fixed panels at mid latitudes to rotating panels. Launch costs are still 10x the cost of a panel. UV and ionizing radiation will destroy your panels sooner. And a space borne panel will probably never reach net energy payback even before you add your laser boondoggle. You're better off just burning the methane.
      - JoeAltmaier 4y ago
        Multiple Gigawatt. Still orders of magnitude better than solar; still less land area. The land-based panels are 42lbs for 450W. The space-based ones are 6W per gram. Lots of room in the equation for cooling. The 89% transmission already figured in weather and absorption; you don't get to count that twice. Rotating panels get what? 25% better? Still an order of magnitude improvement. Launch costs are dropping like a stone. Plan now; it'll be in the hundreds of dollars when you launch. The slang about 'it'll never pay' is just talk. I'd hoped for some information, not just wet-blanket doubt. Like the hot air about 9X being so far from the truth. Turns out, it's just about right. So I guess I'll have to look elsewhere for more information. Somebody will make an orbital station, use it for space-based operations and all the hot air will disappear. And not that far in the future.

by ncmncm 4y ago

JoeAltmaier 4y ago

That's so far a pipe dream, dual-purpose 'negative cost'. Also transmission lines need right-of-way and are not free. Solar flux outside the atmosphere is 9X sea level. Go ahead, look it up. Then there's the periodic eclipse called 'night' that doubles orbital efficiency again. Look that up too. Conversion losses of 20% seem normal? Both in orbit and on the ground. Which halves what you collect, well within the budget of 20X reducing it to around 10X.

ncmncm 4y ago
Solar flux outside the atmosphere is not, in fact, 9x sea level. You can cook the numbers by keeping the orbital panel square on to the sun, while the ground-mounted panel rotates through the day and overnight. But you don't get to count nighttime twice. Conversion losses of only 20% from electric to laser, and again from laser to electric again, would be miraculous. 20% scattering loss in clear weather would be unsurprising. 90% loss, total, would be admirable, not counting the original 60%+ loss off the top. So, even with 9x, and neglecting huge launch cost you still come out behind.
- JoeAltmaier 4y ago
  I looked it up. So about 75% of solar radiation reaches the ground. In the continental US, factoring in angle of the sun, average weather, night that comes to about 4-5KWh per day In orbit you would have just 1.37KW X 24 hours (no weather, angle issues) which comes to about 33KWh per day. So that's 8-9X the collected energy per square meter in orbit vs ground level. These folks https://www.allaboutcircuits.com/news/wireless-power-transmission-of-solar-energy-from-space/ https://www.allaboutcircuits.com/news/wireless-power-transmi... estimate 89% efficiency from orbit to ground. So we're then at around 30KWh effective. What am I missing?
  - Schroedingersat 4y ago
    > What am I missing? So many things. The massive clear area around your receiver. Scattering induced by weather means you still don't have 100% capacity factor. With only radiative cooling available, cooling will take up as much space as the panels and make everything heavier. The atmosphere doesn't absorb light uniformly. Maintenance. You're comparing fixed panels at mid latitudes to rotating panels. Launch costs are still 10x the cost of a panel. UV and ionizing radiation will destroy your panels sooner. And a space borne panel will probably never reach net energy payback even before you add your laser boondoggle. You're better off just burning the methane.
    - JoeAltmaier 4y ago
      Multiple Gigawatt. Still orders of magnitude better than solar; still less land area. The land-based panels are 42lbs for 450W. The space-based ones are 6W per gram. Lots of room in the equation for cooling. The 89% transmission already figured in weather and absorption; you don't get to count that twice. Rotating panels get what? 25% better? Still an order of magnitude improvement. Launch costs are dropping like a stone. Plan now; it'll be in the hundreds of dollars when you launch. The slang about 'it'll never pay' is just talk. I'd hoped for some information, not just wet-blanket doubt. Like the hot air about 9X being so far from the truth. Turns out, it's just about right. So I guess I'll have to look elsewhere for more information. Somebody will make an orbital station, use it for space-based operations and all the hot air will disappear. And not that far in the future.