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edit and update: the assumption here is that necessary batteries for storing solar energy simply aren't available on a global scale (without intending to get into the veracity of such a statement).)


In relation to the question from James, who's moving to the moon, I'm just surprised at the small-scale approaches to solar energy collection prevalent with the space agencies. Particularly in consideration of peak oil, etc, there seems almost a dearth of large scale thinking on energy production.

I suppose the question is: what will it take to generate the grass-roots pressure to effect the political will to seriously look at large-scale solar energy in relation not just to colonization but survival?


I only mean this in the context of total available output of the sun for a dyson sphere, as:

A spherical shell Dyson sphere in the Solar System with a radius of one astronomical unit, so that the interior surface would receive the same amount of sunlight as Earth does per unit solid angle, would have a surface area of approximately 2.8×1017 km2 (1.1×1017 sq mi), or about 550 million times the surface area of Earth. This would intercept the full 384.6 yottawatts (3.846 × 1026 watts)[21] of the Sun's output. Non-shell designs would intercept less, but the shell variant represents the maximum possible energy captured for the Solar System at this point of the Sun's evolution.[20] This is approximately 33 trillion times the power consumption of humanity in 1998, which was 12 terawatts.[22]

of which a small fraction would have tremendous utility both on earth or, as above, on the moon (or mars, etc).

Of course such technology is well beyond current capabilities -- at that scale.

Put another way, what's the break-even point for collecting solar energy in space at scale?

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    $\begingroup$ I don't think that "what will it take to generate the grass-roots pressure" will have a fact-based answer; this will tend to attract answers that are primarily opinion based. Imagine I asked "What will it take to generate the grass-roots pressure to effect the technical will to seriously look at better syntax highlighting color schemes?" in Stack Overflow. Do you think you can focus more on a question that can have fact-based answers? $\endgroup$ – uhoh May 4 '20 at 22:29
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    $\begingroup$ So a 300 W solar panel weighs ~20 kg. According to this SpaceX has brought the launch cost down to \$2720/kg so \$54.4k to fly our panel. Retail cost is $0.75-1/Watt so \$225-\$300 for operating on the ground is ~180x cheaper (installation/operation costs ignored for both) $\endgroup$ – astrosnapper May 4 '20 at 22:39
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    $\begingroup$ I think questions about political will can be asked in Politics SE, however this would also be closed there for "primarily opinion based" as it has no fact-based answer as currently written. $\endgroup$ – uhoh May 4 '20 at 22:40
  • $\begingroup$ yes, @astrosnapper but how much energy does the sun put out per minute? $\endgroup$ – Thufir May 4 '20 at 23:19
  • $\begingroup$ Only about 40% more at the top of the atmosphere ($\sim1360 W/m^2$; source) than at the surface at substantially higher cost to collect. A space solar array doesn't come with a "magic plug"" to directly tap into the Sun, you still have ~10% efficient solar panels and then have to get the power down to Earth (through the same atmosphere). We could solve a large amount of the electricity needs with solar panels on every roof; why don't we ? Cost... (or the hidden/not incuded cost of other methods) $\endgroup$ – astrosnapper May 4 '20 at 23:31
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The scale needed to address human energy requirements in the near future and the scale of things like Dyson spheres are completely different. Human energy usage at present is about 18TW Assuming 20% conversion efficiency and 20% duty cycle, this is an area of solar panels about 700km on a side (at ground level). This would take some building, could be accommodated pretty easily among the world's major deserts and modern HVDC power lines are more than capable of transporting that power where it is needed. Some storage would be needed for overnight.

Building it in space buys you about 40% more incoming light and probably a 60% or so duty cycle (eclipses, maintenance, etc.) so you need about 1/4 as much area. This does not outweigh the costs of building it in space instead of on the ground. Power distribution and storage issues are different, but not obviously simpler.

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    $\begingroup$ You can't just take into account current energy use, though, you also have to consider bringing up billions of people to current Western energy use, and future economic growth. You also have to consider politics and energy security - just because something can be done, such as placing huge fields of solar cells in an unstable nation, is no guarantee it will be. imagine trying to sell that to your populace. Current costs for doing anything in space are also likely to come down in the near future. That being said, there are other ways to tackle the OP's question. $\endgroup$ – Snoopy May 6 '20 at 18:30

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