Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Makani vs Sky Windpower

  1. Sep 29, 2012 #1
    Hallo PF,
    Both are startups working on high altitude wind power generation.

    In general, both uses some sought of kite design to keep the generator afloat in air and the high velocity winds rotate the propellers of generators producing power. However, in Makani the kite travels along a circular path (replicates the tip of actual wind turbine's blade), whereas in Sky Windpower the kite stays STILL in air. I am trying to figure out which one of the two tops in terms of power to weight ratio(I think Makani's principle is solid enough).

    concept Videos of both the companies are provided for your reference. It would be helpful if someone can help me with the above query

    Sky Windpower

    Makani Power

    Last edited by a moderator: Sep 25, 2014
  2. jcsd
  3. Sep 30, 2012 #2


    User Avatar
    Gold Member

    "I am trying to figure out which one of the two tops in terms of power to weight ratio(I think Makani's principle is solid enough)."

    How can you expect anyone to determine which one's power to weight ratio is "tops" given only two youtube videos? The answer must be found through measurement, not by gut feelings.
  4. Oct 1, 2012 #3
    Interesting, I am curious about how the combined weight of the conductive wire returning the voltage to the ground impacts the flight.
  5. Oct 1, 2012 #4


    User Avatar
    Gold Member

    The new scheme for generating electrical power using kites with wind turbine generators seems promising. There is a danger, however, in sending any conductor (antenna) upwards in our atmosphere: there is a potential for attracting a lightning discharge even in clear weather, depending on conditions. Surely the kite generator experimenters must have accounted for this possibility.

    For example: “The electrostatic potential gradient between the Earth and the Ionosphere is about 100Vm-1 near the surface in summer, rising to 300Vm-1 in winter. It is well known that electrostatic motors can be driven by the atmospheric electric field indefinitely from an appropriate antenna and earth connection.”

    For an overview of atmospheric electricity physics, see:

    Finally, ninety years ago there were schemes to “harvest” this electrical potential. See:

    Last edited by a moderator: Sep 25, 2014
  6. Oct 3, 2012 #5
    Ofcourse. If accurate answers are required then actual measurements needs to be made. However, based on working principle I think Makani would provide the best power generated to weight ratio.

    the propeller rpm in makani compared to sky windpower is far greater (thnks to the circular flight path in makani). Also, in sky windpower since the device has to hover, I think this limits the unit size that can be built.

    and regarding the tether, assuming the flight can reach heights of 600 m, what if the flight severes itself (bad wind or mechanical wear...) from tether. The flight can be landed safely. But is it possible for the tether to fall without causing any damage????

    However, since the airborne wind power is something new, a conclusion regarding the effectiveness, problems, etc. can only be reached after 3 to 5 years of usage.
  7. Oct 9, 2012 #6
    Thnx everyone for their suggestions and replies.

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook