1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Possible to extract energy from magnetosphere?

  1. Jun 27, 2013 #1
    I just had this idea/vision of panels being placed in front of the sun, then the energy collected is beamed to a receiver/transmitter orbiting Earth. I suppose with an energy 'Magnitude' of the sun, a little bit of 'loss' due to Earth's atmosphere is not a big deal but... I wondered what if you could 'saturate' the Earth's magnetosphere and then draw energy from that... instead of building a receiver on the ground of Earth. The receivers on the ground could then just point at the sky to receive power.

    Anyway, assuming that all of my ideas are probably wrong, like a misunderstanding... if such an idea was possible, would Earth's laws not allow someone to mess with the Magnetosphere?

    I just thought with radio propagation and all through space without inhibitance (haha made up words), then it isn't really necessary to transport panels close to the sun.
  2. jcsd
  3. Jun 27, 2013 #2


    User Avatar
    Science Advisor
    Gold Member

    there's more energy "falling" directly into the magnetosphere from the sun than what you could ever collect on earth and transmit back up to it

    all in all... a totally waste of time, sorry

  4. Jun 28, 2013 #3
    No need to be sorry, it was just an open question without backing.

    I read this 'fact' from a book I found in the basement of the physics department of a University I used to attend.

    For every square mile of direct sunlight exposure, there is five million horsepower.

    Does that seem right? And if so, is it just about money then why this isn't being followed?
  5. Jun 28, 2013 #4


    User Avatar
    Science Advisor
    Gold Member

    dunno if that's a correct figure, would have to work it out
    but a figure more useable is ~ 1kW / metre2 ... from memory, that's an approx. avg. as there is more under direct overhead sun at equatorial regions compared to high latitude

    then depending on how you intended sending it back to the magnetosphere and the losses involved there, an RF ( radio) signal is VERY lossy.

    you would in the long run still be better off somehow directly generating energy from within the magnetosphere and beaming to earth and getting rid of 3 major inefficiencies ( big losses) of your original system

    NASA have experimented with towing a tether from a space shuttle a few years back for electricity generation. cant remember the final results ... I think the tether broke ?? do some googling

  6. Jun 28, 2013 #5
    An electrodynamic tether is essentially a homopolar generator/motor http://en.wikipedia.org/wiki/Electrodynamic_tether
    It can convert kinetic/potential energy of a spacecraft into electricity and the other way around. But it doesn't extract energy from the magnetosphere.
  7. Jun 28, 2013 #6


    User Avatar
    Science Advisor
    Gold Member

    not really....

    you obviously didnt read all the link you gave
    from wiki

    Main article: Electrical generator

    its still more to do with good old fashion cutting through a magnetic field with a moving wire power. generation
    The movement of the wire is just being accomplished by a different method. The magnetic field is still needed

    Last edited: Jun 28, 2013
  8. Jun 28, 2013 #7
    This does not contradict my statements. A wire continuously cutting through a magnetic field to produce a direct current is a form of homopolar generator. And even though the magnetic field is important for this to work the energy does not come from the field but from the motion of the wire.
  9. Jun 28, 2013 #8
    might be possible, but it probable wouldn't be very efficient, you'd have too many things contributing to energy loss (I'd have to think a main one would be the panels moving/vibrating from the energy instead of storing it electrically). By the time it would be plausible we'd have much more efficient means of energy production anyway...
  10. Jun 29, 2013 #9
    Intriguing conversation. I didn't know wp had an entry like that. I've actually thought about a version of this. Suppose a wire-wound inductor the size of a Grey-hound bus could be built and put into an orbit just a bit higher in altitude than a standard geosyncronous orbit so that it's path around the Earth was at a 90 degree angle to the magnetic field. Suppose that satelite or "rotor" was tethered to the Earth with a pair of conductors built in. As the rotor "cuts" the lines of flux, there would be gobs of current (yes, i typed "gobs"). Wouldn't this basically be a (macro) motor? And i believe it would be DC, yes? Of course the obvious challenge is the tether. The stress would be significant and not necessarily static. But imagine if something like that could be built.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Possible to extract energy from magnetosphere?