Myriad's Midgard Serpent: does the concept work?

Since there has been some discussion of tides here recently, and some discussion of altering the earth's rotation, I though I'd bring this up.



Some weirdo calling himself Myriad, in a blog post, has described a Nivenesque power generating scheme involving a massive body "orbiting" just under earth's surface in a frictionless equatorial tube, coupled to the moon's tidal pull.



The initial post is here. A rather wordy update with more detailed discussion was just posted here.

Quote:

Originally Posted by Myriad Once the Serpent is brought up to it's thousand mile an hour operating speed, it takes up a position that's fixed in a certain way relative to where the moon is in the sky. To maintain that position it must careen nearly all the way around the earth each day as the earth rotates. The ideal position is centered about three thousand miles (forty-five degrees) east of the moon's position over the earth, where the gravitational power transfer from moon to machine is maximized... The speed of the Serpents, while it presents technical challenges for its construction, is what makes the gravitational tether effective. "When the tide acts on the oceans, it generates a lot of power because the oceans are so massive," explains Myriad. "But the tidal pull changes direction four times a day, and the water doesn't get pushed very fast or very far. So the power of the ocean tides, even though it dwarfs the Midgard Serpent in absolute terms, is very diffuse and difficult to harness. With the Midgard Serpent, the tidal force acts upon the moving mass through a distance of over a quarter mile each second, always in the same direction, pumping power into it. Energy is force times distance, and power is force times speed. It acts like a focusing lens for collecting tidal energy."

What I want to know is, have I has Myriad missed anything important? As impractical as it is, is it conceptually sound? And has anyone described such a device before, in SF or a science essay somewhere?

via International Skeptics Forum http://ift.tt/1C4Gbrg