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At the rate we are using energy, it is inevitable that we will need to source energy from outside of Earth, eg from space. I was wondering how one would transfer this energy from that energy collector (e.g. a solar array) to Earth to be used by us?

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    $\begingroup$ Where do you think our energy comes from now, exactly? There's only four sources of energy available to us: nuclear, solar, lunar, and geothermal. Most of the ones we use today (petrolchemical, wind, water, etc) are just convoluted forms of solar. $\endgroup$ – corsiKa May 10 at 18:34
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    $\begingroup$ "The United Nations Development Programme in its 2000 World Energy Assessment found that the annual potential of solar energy was 1,575–49,837 exajoules (EJ). This is several times larger than the total world energy consumption, which was 559.8 EJ in 2012.[3][4]" en.wikipedia.org/wiki/Solar_energy $\endgroup$ – Acccumulation May 10 at 20:45
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    $\begingroup$ Can you clarify “at the rate we are using energy”? Is there a study showing power demand outracing supply? $\endgroup$ – JoeTaxpayer May 11 at 0:56
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Various aspects of space-based solar power systems are described on this wikipedia page To summarise briefly, the power is beamed down as electromagnetic radiation of some frequency to which the atmosphere is reasonably transparent. This is most likely to be optical or near IR or microwave. Microwave power can be converted efficiently at the Earth end, but the antennae needed are much bigger. Optical or IR solutions involve more loss, but can be done with smaller ground stations.

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    $\begingroup$ But there already is a space-based solar power system that is beaming down electromagnetic radiation of some frequencies to some of which the atmosphere is reasonably transparent. $\endgroup$ – Ghanima May 10 at 19:00
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    $\begingroup$ @Graipher, sure, but a civilization that burns 500 tons of fuel to get 10 tons of payload to LEO (which is not even remotely the place you'd want your Dyson swarm at) is probably not at the right point in their development to do such a thing. $\endgroup$ – Ghanima May 10 at 19:14
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    $\begingroup$ @Graipher "But it is limited by the surface area of the Earth facing the sun, whereas e.g. a Dyson swarm is only limited by the amount of material available in the solar system/within reach of the civilization." I doubt that. Beaming a large amount of energy to the Earth would pose massive logistical problems. And all of this would be extra energy that's being added to the Earth. While solar panels are simply intercepting energy that would have gone to the Earth anyway, a Dyson swarm is adding net energy. $\endgroup$ – Acccumulation May 10 at 20:52
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    $\begingroup$ A GEO power satellite with a microwave beaming system to the ground (eg MASER) could be more efficient than ground based PV panels as the GEO sat would always have no night, no atmosphere, and no weather. $\endgroup$ – Dragongeek May 10 at 23:41
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    $\begingroup$ @user4574 All energy ends up as heat eventually. All the energy sent from the satellite to the Earth, may as well be heat, as far as Earth's temperature is concerned. Unless it's being sent again from Earth to somewhere else (in which case only a percentage becomes heat on Earth, and the rest becomes heat somewhere else) $\endgroup$ – immibis May 11 at 2:49

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