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In the universe there are several worlds where energy harvesting is feasible without pesky wild life habitat preservers standing on your patch'o land bare breasted.

So earth has set out to harvest energy from other worlds to keep earth green and blue and open for free range nature lovers.
Through a lucky invention we found out a way to very quickly(near light speed, 0.99c) transport material and people through the universe, we just haven't knacked a way to get off a planet in an energy efficient way yet so we still use these days rockets to get off this rock)

In a reasonable timespan Earth has set up some bases on several worlds to gather energy. Thermal energy from volcanic active worlds(like io), tidal energy from oceanic worlds(europa), wind energy from planets with an active atmosphere(venus). We also have some nuclear reactors buried in the moon, just to have something close, but keeping it supplied with water and fuel and crew not dead has been a hassle so on other worlds has been chosen for reneables. Scout missions are under way or building already on remote worlds in different solar systems, but sadly we haven't heard back yet.

The world will be roughly the same as ours, except maybe a hundred years in the future or a bit more, but not much has changed in energy needs except that fossil fuels are out and all is electrical. The energy need that existed in fossil fuels is now replaced by the equivalent in electrical.

How do they get the energy off the planets on the way to earth in a way that the energy price on earth would not differ from what it is today, and the energy need stays roughly the same(see the led light suprise, leds are brighter, more energy efficient, so naturally we use more because it costs the same).

Some options I thought of:

Huge lasers through space reflected by satellites to a specific point on space to boil lots o water for steam power and water desalinization and salt production. Cons, might be hard to keep the beam focused over large distances.
Energy pods: Concentrated energy in batteries. Might be to costly to launch those in space, cons: heavy, weighs a lot, how do we get it on earth without it burning up or poisoning the lands on a faillure.
Fusion produced helium3: There are reactors powered by the planets that produce helium3 thats shot to earth where it's used in reactors to generate energy. cons: You need launch and gather mechanisms, costs a lot for possibly little gain.

Which would be most economical, or is there a better way to keep earth green and cat videos on the internet?

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  • $\begingroup$ Everything must be compared to the cost of a PV panel on your roof at around £1/W and falling $\endgroup$ – Separatrix Feb 16 '18 at 8:57
  • $\begingroup$ How far are these planets? Also, @Separatrix has a point, Sun is sending a lot of energy, for free. We just need to catch it. Why would you even want other planets involved? $\endgroup$ – Mołot Feb 16 '18 at 9:08
  • $\begingroup$ Other planets/moons at this point in our solar system(io, europa, mars, venus) because the nature on earth should be free, unrestricted, and views should be free of wind farms or solar panel/mirror fields. The advantage of other planets is it's easy to build into, natural shielding, provides stop points for exploration, natural resources harvesting etc... but the main goal in the beginning is energy production so earth can be big and natural so all animal and plant species can thrive. Burning birds with mirrors or destroying deserts for sun has become a taboo $\endgroup$ – Tschallacka Feb 16 '18 at 9:37
  • $\begingroup$ For most domestic purposes, roof mounted PV panels are sufficient, there's no need for big industrial power generation apart from for big industry. Your approach will make importing power your biggest industry, better to send all your heavy manufacturing off planet and let them set up big solar farms on the moon to generate power, while the general population cut themselves to 12v dc locally generated. $\endgroup$ – Separatrix Feb 16 '18 at 9:50
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    $\begingroup$ You need some receivers on the surface anyway, and solar farm on orbit would be cheaper than one on another planet. And less distance to send energy. So, why other plants, again? $\endgroup$ – Mołot Feb 16 '18 at 17:01
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You're forcing a story to meet a political agenda. OK. Let's ignore the fact that manufacturing creates more pollution and greenhouse gasses than energy production ever could (coal-fired power plants are a conveniently easy symbol of our problems, but they're far from the root cause). Curiously, National Geographic once claimed agriculture produced most of the pollution and greenhouse gases on our world... but let's ignore all that and assume energy production is the problem.

  • The closer you are to the sun, the less surface is needed to capture the same amount of energy. Thus, harvesting from Venus and Mercury is more efficient than anywhere else in the solar system.

  • Moons, asteroids, planetoids, etc., are a complete waste of time. Too small.

  • You don't have a firm surface to work with (at least not one that isn't 100% covered by opaque atmosphere) on Jupiter or Saturn, the largest of the outer planets, so they're out.

Frankly, none of the outer planets can help you much. You just can't collect enough energy to make it worth your while. The inner planets also have problems, like when they're on the other side of the sun and can't beam a thing back to mother Earth.

You'd be better off creating massive solar panel arrays in Earth's LaGrange points and convert the energy to dense EM beams. Or use large mirror arrays that reflect the light to pre-determined spots on Earth. Except there's a problem...

Earth is rotating. That means you either have (a) a band of collecting material circumnavigating the earth or (b) you can only send your "beams" in bursts when the collectors are at the right point.

Closer is better. No matter how well focused, energy dissipates over distance. The further away you need to beam it, the less of it will actually arrive. Using other planets sounds cool, but will never be efficient or economical.

This sounds an awful lot like an answer or comments from another question. I'm getting the horrible feeling of deja-vu.

Ah... here it is This question might actually be a duplicate of that question.

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  • $\begingroup$ I have to downvote only because the vast majority of this response doesn't actually answer the question $\endgroup$ – bendl Feb 16 '18 at 17:30
  • $\begingroup$ @bendl, how does the majority of the question, which explains why the OP's solution is too inefficient and uneconomical to work well, not answer the question? Some questions must be answered, "no." $\endgroup$ – JBH Feb 16 '18 at 17:43
  • $\begingroup$ the question assumes we already have some sort of energy production infrastructure up on different planets and the moon, so the relative merits of different planets and asteroids, although totally valid, is irrelevant, and placing something at the LaGrange point seems invalid. The final part could do with at least a back of the envelope calculation for how efficient your setup could be. $\endgroup$ – bendl Feb 16 '18 at 17:52
  • $\begingroup$ @bendl, you're correct that the question presumes the pre-existence of the bases. That doesn't change the fact that the answer can be "no." The solution is too inefficient to ever be practical. The OP's placement of the bases was, itself, based on the assumption that it could be practical, which the OP didn't realize was inappropriate. $\endgroup$ – JBH Feb 16 '18 at 19:16

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