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You Are My Sunshine
A Lunar Solar Farm

A Japanese company thought way, way beyond the box with this idea: putting a ring of solar panels around the moon’s equator and beaming that energy back down to earth.

The plan, drawn up by the design firm Shimizu, would involve mining the moon for materials and building the panels en situ. Once built, the “Luna Ring,” as it’s being called, would capture solar radiation and transmit it to terrestrial receiving facilities by microwave or focused laser. The best part: the energy supply would be round-the-clock, doing away with solar energy’s intermittency problem.

If that seems like an outlandish, outrageously expensive and unrealistic endeavor, that’s because, well, it is. And, as Wired points out, the hurdles extend beyond the realm of logistics:

[T]he Shimizu Corporation might want to consider the problems that may arise out of the appropriation of extraterrestrial real estate before it starts building space robots. Outer space law is notoriously difficult to apply in practice and may scupper the plans long before anything gets built.

This idea is much more fiction than it is science, but when tackling such massive problems like finding a zero-carbon base load planetary power supply, it helps to get creative. And, as the pace of technological innovation continues to accelerate, dreams like this one may be achieved sooner than we might expect.

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  • Fat_Man

    OMG. Imagine what would happen if one of those beams went a little off target. Nuclear really would be safer and cheaper.

    • Jim__L

      Depends on how strong the beams are. You could calibrate the beam to be no more than a fraction of the sun’s power, and still use it for energy production.

      • Fat_Man

        No. The beam must be far more concentrated than sunlight or the project is a waste of resources.

        • Bill_Woods

          It doesn’t actually, because a beam of microwaves can be converted to electricity with far higher efficiency than sunlight.

          • B-Sabre

            Exactly. My “rectenna” can be kilometers in area if I want it to be. See the artwork linked below:


            The problem is that you need freaking huge solar arrays to make this work.

            Some of the designs for solar power satellites in the 1970’s envisioned arrays the size of Manhattan Island (!) in orbit, with all the attendant infrastructre necessary. We’re talking about launchers in the million-lb (450,00 kg) capacity class and upwards of a 1000 people in orbit at a time (when the current world record is, what? 9? 10?) for the care and feeding of said infrastructure. With limited results:

            Had work begun on SPS in earnest in 1980, the first flights might have started in 1990 or so. By which point we’d be two decades into the project. Assuming they kept on schedule (ha!), we’d now have at least 40 SPS satellites, each providing 2.5 gigawatts of net electrical power. That’s 100 gigawatts; over a year, 876,000 gigawatt-hours. Energy usage in the US today is about 29 petawatt-hours = 29,000,000 gigawatt-hours. Thus… a whopping 3% of todays American energy needs could be filled by twenty years worth of solar power satellite construction.


          • Fat_Man

            My “rectenna” can be kilometers in area if I want it to be.

            And the wire and the land cost money. Who is going to pay for it.

          • B-Sabre

            If you’re paying billions to develop, test, build and launch rockets capable of throwing million-lb payloads into orbit (about the total mass of the International Space Station, which took us 15 years to build in orbit) at a single go, then stringing a bunch of wire is the least of your costs.

          • Fat_Man

            First, noonday sunlight causes burns. Microwaves at those fluxes would cause burns too. Therefore, your dilution of the beam would have to be fairly high. and the antennas would have to be correspondingly larger.

            Second. the moon, like the sun, sets everyday, so you need to supply storage or a complementary source of power. Further, from the view point of the earth the moon rotates portions out of view (the phases of the moon), this would be either an additional limitation on power availability or require a lot of additional investment in the system.

  • Jim__L

    Er, why are they going to the Moon when GEO would be easier, cheaper, and more effective?

    • Bill_Woods

      Well, you have to go to the Moon anyway, for the materials to build the solar collectors. But yeah, putting them on the Moon instead of GEO cuts energy production per panel by two thirds and requires redirecting the beam several times each day to a series of receivers around the Earth.

      • Jim__L

        NEAs are another option for materials, and there are some nifty astrodynamic tricks you can use to get them back to GEO without much delta-V.

  • Jacksonian_Libertarian

    This is never going to happen. If you think green energy boondoggles are expensive, how much do you think this pie in the sky would cost? And then there’s the question of it being turned into a super powered beam weapon, capable of delivering gigawatts on target with pinpoint accuracy.

  • Nick Bidler

    well, bless their hearts for dreaming big, but this is just a bridge too far.

    unsubstantiated claims: natural gas will be a bridge energy. cold fusion is still a long ways off but making progress. better solar cells and wind turbines are nice but the real prize for any sort if renewable energy is miracle batteries (the sort that graphene has recently proved possible but not economical).

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