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NSSO on Space Based Solar Power

Posted by samzenpus on from the it-is-always-sunny-50-miles-up dept.

apsmith writes "About a year ago some of the people at the US National Security Space Office began looking into space-based solar power (SBSP) as a technology in the near-term strategic interests of the United States. At first the participants were skeptical, and the "phase 0 study" went along with no official funding. In a rather innovative move, they organized the study as a series of internet-based (bulletin-board and email) discussions, with the wordpress site open to the public, and a closed experts-only discussion using Google Groups. Initially expecting only a dozen or so interested parties, the discussion grew to include over 170 people with past expertise and interest in the issues. The final report was released Wednesday morning; it provides an excellent broad-brush review of the status of SBSP, showing immense potential, but also a number of challenges that appear only surmountable with a strong government commitment to the project. The big question is where it goes from here — NASA? DARPA? The new ARPA-E? Or something new? I was able to attend the press conference, which included Buzz Aldrin in an announcement of a new alliance to push for implementing the recommendations of the report."

10 of 198 comments (clear)

  1. Ok, someone explain it to me by iamlucky13 · · Score: 4, Insightful

    How is it better to lift your solar panels into orbit, generate your electricity, then beam it to the surface at (optimistically) 50% efficiency, and then receive the beamed power at (optimistically) 50% efficiency, meanwhile creating the navigational hazards of the power beams and still requiring distribution from receiving stations rather than simply generating it via panels at the point of use?

    Don't get me wrong, I'm all for finding ways to utilize space, but I don't see how this is even remotely economical, especially at our current technology levels.

    Convince me.

    1. Re:Ok, someone explain it to me by Jubedgy · · Score: 5, Informative

      Portability and extensibility. The sun provides, about 1367 W/m^2 in space (courtesy, Space Mission Analysis and Design third edition, page 432) and about 250 W/m^2 on the Earth's surface (FTFA). In any case...

      Portability:

      By using an orbital energy collection system, you can simply re-route the beam to any place on the planet within the system's FOV...done right, you can get full 4*pi sr coverage of the Earth 24/7. Design a portable ground station, and you can provide power to a disaster area that has been removed from the rest of the power grid (paraphrased directly FTA).

      Extensibility:

      If, once in place and a standard orbital collection platform design has been established, more power is required, simply launch the spare unit. Proper formation flying techniques (something currently at about the cutting edge of orbital design) should allow the new unit to 'hook in' to the system to boost the amount of available power. This may be in the article, I have not finished reading it yet.

      The LISA mission provides a pretty good overview of how I see the entire system distributing power from the collectors to the emitters (the things that will transmit the power down to the surface), though I may be totally off base from what the authors have in mind. The LISA mission will consist of three satellites forming an equilateral triangle with leg lengths of 5 million Km shooting lasers at each other. Last time I checked, anyway.

      It is currently not economical, nor is it really achievable yet. I encourage you to at least browse through the article as it does discuss some of your questions in a more cogent manner than I have.

      --
      Si hoc legere scis nimium eruditionis hebes
    2. Re:Ok, someone explain it to me by lgw · · Score: 5, Insightful

      How is it better to lift your solar panels into orbit, generate your electricity, then beam it to the surface at (optimistically) 50% efficiency It's better because now you have a hugely powerful microwave cannon in orbit that can fry anyone you need it to. Thinking about an orbital power station other than as a weapon is probably misguided. This is probably a feature for the "National Security Space Office".
      --
      Socialism: a lie told by totalitarians and believed by fools.
    3. Re:Ok, someone explain it to me by Lloyd_Bryant · · Score: 3, Interesting

      There is no nighttime in space, nor any clouds, nor any seasons, nor any atmosphere. Solar panels in orbit deliver full power 24 hours a day 7 days a week 365 days a year with no need for fuel or maintenance. And they don't have to be, and probably shouldn't be, in orbit. Inject them into an orbit between Venus and Mercury, or closer still. Solar radiation falls off with the square of the distance. The closer we get them to the sun, the more power they will generate, by orders of magnitude. First off, putting them somewhere other than Earth orbit is silly - yes, you can get more energy from the Sun, but how do you transmit it to Earth? The microwave (or whatever) beam will also fall of with the square of the distance.

      And how exactly do you keep the power beam locked onto the target, when the target is on a sphere rotating once per day?

      Putting them in equatorial geostationary orbits is *much* simpler. You'll lose a small amount of generating time each day (while the station is in Earth's shadow), but if you schedule as much of your maintenance as possible during this time, the effect is minimal.

      And maintenance *will* be required, for the foreseeable future. Someday we may be able to build solar cells that don't need to be periodically replaced, but not today.

      Furthermore, it's been noted that Earth orbit is "halfway to anywhere in the solar system" (attributed to Heinlein). So we'll need serious orbital capability to build these things, regardless of where we put them.
      --
      Don't tell me to get a life. I had one once. It sucked.
    4. Re:Ok, someone explain it to me by TripMaster+Monkey · · Score: 3, Informative

      Actually, carbon nanotubes ("buckytubes") are quite good conductors of electricity.

      So that problem's solved...leaving only the original problem of manufacturing enough defect-free tubes in enough industrially-significant quantities to make the skyhook in the first place...

      --
      ____

      ~ |rip/\/\aster /\/\onkey

    5. Re:Ok, someone explain it to me by QuantumG · · Score: 5, Informative

      The sun provides, about 1367 W/m^2 in space (courtesy, Space Mission Analysis and Design third edition, page 432) and about 250 W/m^2 on the Earth's surface (FTFA). Hmm.. the first number is correct, but we don't have 100% efficient solar panels and won't any time soon (if ever) so you've gotta down rate that.

      The second number, however is totally wrong. If you're going to talk about what "the sun provides", i.e., the theoretical 100% efficiency solar panel, then you get a figure of about 1000W/m^2 on the Earth's surface. You could say it is more like 800W/m^2 when you take cloud cover into consideration.. and then there's the fact that you only get that during daylight hours, so halve it to get 400W/m^2 but that's still a lot more than 250W/m^2. It *feels* like someone is downplaying the possible efficiency of solar panels on the Earth's surface vs the same solar panel in space in order to make their argument stronger. As you took that figure straight from the article, I'll give you the benefit of the doubt, but that's what it sounds like.

      It's still a heck of a lot of difference though. You're talking nearly 3.5 advantage to putting your solar panels in space over leaving them on the ground.. but there *are* losses to transmitting the power as microwaves through the atmosphere, and there is the astronomical cost of launching anything into space.

      Whenever I hear people talk about solar power satellites I'm reminded of the episode of Seinfeld where they stock the mail truck with bottles to collect the 5c deposit in the adjacent state. If you can get a free ride you might be able to make solar satellites work, but you've still gotta crunch a lot of numbers first, and no-one has done that successfully.

      --
      How we know is more important than what we know.
    6. Re:Ok, someone explain it to me by B3ryllium · · Score: 3, Funny

      At least it would ward off that dreaded Global Cooling disaster we've all been hearing about.

  2. Because you don't need batteries... by Goonie · · Score: 4, Informative
    There are several advantages space solar power has:
    • higher intensity sunlight than even a cloudless day, 24 hours a day
    • you've always got direct sunlight, so you can use cheap mirrors to focus the light on a very expensive but efficient solar cell (you can do this on Earth as well, but it doesn't work as soon as you get clouds)
    • No need for backup power. That's worth a lot of money.
    • The ground based gear is much smaller and lighter than equivalently-powerful terrestrial solar panels. This is a big advantage for the military, who are the proposed initial customers.

    I'm skeptical too, but it's not quite as crazy as it sounds.

    --

    Any sufficiently advanced technology is indistinguishable from a rigged demo
    --Andy Finkel (J. Klass?)
  3. The difference between... cannot go wrong by cumin · · Score: 3, Interesting

    Douglas Adams - "Mostly Harmless"
    - The major difference between a thing that might go wrong and a thing that cannot possibly go wrong is that when a thing that cannot possibly go wrong goes wrong it usually turns out to be impossible to get at and repair.

    Lets build in some redundancy shall we? (Just in case.)

    I think you covered the list pretty well but corrosion is also a factor that space should mitigate. Well, mostly aside from the wandering bit of space debris.

    I haven't RTFA, probably won't, but I'd like to throw in the additional suggestion we look into Von Neumann devices to build most of the components on a lunar base. (Earth first, and strip-mine the moon later.)

    --
    Back in my day when we chiseled our bits into stone and sent them by mule train from village to village...
  4. Jimmy Carter must be laughing his ass off by theolein · · Score: 4, Insightful

    I remember, back in 1980 or so, when all the Reagan fans were jumping for joy because the actor was more popular than a naval nuclear engineer (yes; Carter actually knew his shit), Carter had proposed a system of orbital solar power stations. It would have been more or less the same thing as they are proposing today. Those of you who have access to Time magazine's archives will find an article on it.

    So, here we are today, some 27 years later, and the same proposal gets floated.

    Imagine if laziness hadn't dropped the issue back then. Iran, Iraq and the whole business of 9/11 would have been less critical than they now are.