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Solar power from space elevator

No more nasty laser beams
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A problem with an orbital solar power station is that if the beam transmitting the power back to Earth goes wonky, it will fry random portions of the Earth rather than providing electricity, which isn't very ecologically sound. This could be avoided by replacing the beam with something like a cable.

A space elevator cable could end in a solar power station. Situated along its length could be rotating annular solar panels kept spinning at the appropriate speed to prevent them from leaving orbit, and powered by electromagnetic induction from the solar power they gather. The surplus electric power they generate, which could be considerable as they would be spinning in a near vacuum, could then be beamed to receiving stations situated on the cable itself, which themselves transmit further down the cable. Also, at the level of the Van Allen belts, extra power could be generated through induction because the cable would be moving through charged particles.

This would be safer than using a beam to transmit energy back to the Earth, and if the cable snapped the suspended power stations would stay in space. The elevator would also then provide energy to power itself.

Incidentally, i realise the space elevator has been proposed as a source of solar power, but i don't think the details have been worked out in the way i describe.

nineteenthly, Nov 24 2007

Immediate inspiration http://www.newscien...g-into-the-sun.html
Although Asimov thought of it in 1941. [nineteenthly, Nov 24 2007]

Reason http://en.wikipedia...Reason_%28Asimov%29
Asimov thinking of it first. [nineteenthly, Nov 24 2007]

The Space Solar Power System http://www.usef.or....t/ssps/f3_ssps.html
Those plucky Japanese are going for it! Yay! [DrBob, Sep 16 2009]

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       His 1941 story, 'Reason', is set aboard an orbiting solar power station which beams the energy to the Earth with microwaves. The robot that's supposed to do this doesn't believe in the Universe outside the space station and the human characters are concerned it won't keep the beam focussed but it does, so they decide it doesn't matter what it believes and leave.   

       However, yes it does seem rather odd he didn't go on and on about it. Then again, there aren't any real orbital solar power stations yet.
nineteenthly, Nov 24 2007

       No worries. Actually, in the process of finding out if anyone else had thought of this, i looked up orbital solar power stations on Wikipedia and the earliest reference was from the 'sixties.
nineteenthly, Nov 24 2007

       One of the problems with space elevators is how to power them, as the cable is too long to transmit power along.   

       Also, I don't know how you imagine that having spinning stations along the cables length will stop them leaving orbit. Also, if the cable snapped, they would not stay in place.
marklar, Nov 25 2007

       The idea behind the spinning stations is that if they were attached to the cable, it couldn't be used as an elevator, and they need to move in order to stop them falling. That is, they spin at orbital velocity.   

       Concerning the power issue, how about this? The space elevator is powered by the solar power stations all the way up, swapping from one to the next. There is no transmission to the ground at all. Instead, the elevator contains a storage battery which is charged by the power stations on the way up and down. When it reaches the top, it uncouples and moves over to a second cable. This makes a long chain of elevators possible, each carrying a battery and keeping their mass down.
nineteenthly, Nov 25 2007

       Correct me if I'm wrong but I believe you are proposing each panel stays near but not attached to the cable. How do they regulate their position? They cannot rotate like a satellite because at various heights you need different velocities to stay in orbit.   

       Also, how much power does this generate?
hugeboofhead, Nov 25 2007

       They would indeed rotate at different velocities. This is where i'm on shaky ground. I'm assuming that an object moving at orbital velocity does not actually need to move in an orbit to avoid falling. Say an object was at ground level, without an atmosphere. If it was moving horizontally at 25000kph, my assumption is that it would stay at the same level. The possible flaw in this is that orbits are always conic sections with the barycentre at one focus, and this might not be because it would actually be a circle in a plane at right angles to the direction of gravity.   

       Concerning how much power it would generate, a square metre in space near the Earth receives 1.4 kW. It depends on efficiency, the area of the collecting surfaces, their angles and the mass of the elevators.
nineteenthly, Nov 25 2007

       Orbital velocity is the velocity of an orbiting object.   

       The angular velocity of an orbiting object is proportional to radius*sqrt(radius) of the orbit, so objects at different heights must travel at different angular velocities to stay in orbit.
hugeboofhead, Nov 25 2007

       Right, i thought that might be so. In that case, what about a sort of banana-shaped path, or an orbit with a pole of precession which is close to the cable? Then it could collect radiation and transmit power to a receiving station on the cable as it passes.
nineteenthly, Nov 25 2007

       It's shaky, but I reckon this is reasonable enough to be halfbaked. Bun, especially because you read Asimov.
Germanicus, Nov 25 2007

DrBob, Sep 16 2009


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