Very interesting, but how much energy is required for the maglev itself? I rather suspect that it is several orders of magnitude greater than the energy harvested.
Boffins use laser to move maglev disk
Readers may wish to skip to the video, below, if they’re too holidayed to want to read too many words. For the rest: a group of Aoyama Gakuin University researchers has demonstrated a magnetic-levitation disk that can be moved using lasers. The trick is in the materials: when the laser heats one part of the disk, the magnetic …
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Monday 31st December 2012 10:01 GMT Thomas 4
Re: Perhaps none.
You'd also need to factor in the energy costs of the laser, unless sufficiently focused sunlight might do the trick (i.e. similar to a magnifying glass). It also depends on the type of magnet being used as well. If it's one of those super-cooled magnets, the amount of energy required to reach the necessary temp might be prohibative.
One other thought is that although they can heat only a specific section of the magnet, what stops the heat spreading through the rest of it? If the magnet reaches it's Curie point, it'll lose its magnetism. (I learned about that from one of those "Choose Your Own Adventure" books! ^_^).
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Sunday 30th December 2012 21:36 GMT G R Goslin
pie in the sky
Sheer pie in the sky. Hysteresis losses in the disc from heating and cooling will far far greater than the energy converted to the dynamic. I've vague feeling that even the ancient greeks had bettered this. A long iron bar, alternately exposed and shaded from the sun would operate a ratchet with truly enormous forces. Even the shading function could be built in, and automatic. Wouldn't work in this country, mind. No sun.
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Sunday 30th December 2012 21:58 GMT John Smith 19
The real question is why no one has "ever" thought of this before.
It's so simple
It's a graphite disk sitting on top of a stack of magnets and having laser shined on it.
No tricky materials, no exotic laser frequencies just a simple study of what happens if you try to do this.
Will the losses exceed the torque? Who knows. This is a demonstration not an engineered concept. But it is clever.
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Monday 31st December 2012 17:47 GMT Anonymous Coward
Its certainly interesting
Have some PG and the required Holbach array (4 crossed pole magnets) to try this,
Its feasible to simply make a flat magnetic pad with crosspoints, an array of fluid lenses and PG disk above each crosspoint with mechanical limiters, then tap off energy with a large transparent coil made of ITO or graphene and apply offset voltages to track the Sun.
Literally energy for free, the energy needed to make pyrolytic graphite is considerable but this can be worked around by mass producing it on a silicon wafer then dicing it.
The magnets are the major sticking point as they are rare earth and neodymium is pretty expensive.
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Wednesday 2nd January 2013 11:28 GMT John Smith 19
Re: crookes radiometer
The Crookes radiometer looks very impressive. A windmill powered directly by sunlight!
In reality the force generated by photon pressure is tiny. I've seen a figure of 4.5 micro N/m^2.
What's really happening is differential absorption by the black sides of the vanes and local heating of the air near the surface of the vanes exerting a force to push on the vanes. This force is much bigger. A "real" Crookes radiometer could operate in a vacuum. The air pressure inside the globe is an integral part of the device.
I've sometimes wondered if such vanes, enclosed in a transparent slightly pressurised housing would make a good power generator on the Moon.