could magnets be used to create a renewable source of energy?

[Bonfirelight]

you lot are a bunch of thickos

any clearer?

i have 2 ideas for renewable energy, but i'm not saying anything incase you steal them.

 

[Crispy]

A current is induced in the super conductor.

A current cannot exist without a voltage to drive it.

If you have voltage and current you have power (watts).

This power, being induced comes from the magnet hovering over the superconductor.

So either

a) the magnet has to 'discharge' itself becoming rapidly weaker in the process.
b) the magnet has to change it's matter to energy becoming lighter in the process.
c) the magnet has to 'recharge' itself by some means.

Although magnets do get weaker over time it is normally a very long period. I have never come across a case where a magnet becomes lighter due to converting it's matter into energy so that only leaves option (c)

So how does a magnet 'recharge' itself?

A superconductor does not need a voltage to induce a current, because voltage is only required to overcome resistance. Volts=Amps*Ohms. As a superconductor has a resistance of 0, the voltage is also 0. It's like saying you need a voltage to keep an electron flying through the vacuum of space (which you don't).

Superconductors require constant power to keep them cool. In space, shielded from external sources of heat, a superconductor won't need external power (I think - someone confirm this for me?)

Magnets losing their strength over time is not due to the 'magnetic energy' or whatever running out. It is because a magnet's strength comes from the coherent alignment of the magnetic fields of the individual molecules and crystals inside it. Over time, the interaction of external objects with the magnetic field causes very small physical forces to shuffle them around, so causing the particles to become mis-aligned.

 

[stdPikachu]

Superconductors require constant power to keep them cool. In space, shielded from external sources of heat, a superconductor won't need external power (I think - someone confirm this for me?)

IIRC space is cool enough for some superconductors (niobium alloys are found to be superconductive at temps of 16K or higher), but they still require external cooling due to heat from radiation. Hubble has a few near-superconductive instruments, but they're generally cooled by blocks of solid nitrogen (I think) that slowly evaporate over time.

Magnets are "recharged" by applying a strong magnetic field over them to re-align the internal magnetic fields. Magnets can be "de-charged" by a sharp knock (sufficient kinetic energy to bump the fields out of alignment) or by heating past the metals Curie point.

 

[WouldBe]

A superconductor does not need a voltage to induce a current, because voltage is only required to overcome resistance. Volts=Amps*Ohms. As a superconductor has a resistance of 0, the voltage is also 0.

A current will not flow unless a force is provided to cause the electrons to move.

Link

The electromagnets, which consists of wire coils, must carry very large electrical currents without melting in order to produce very large induced magnetic fields (on the order of 1 Tesla). Superconductors are used to build the wire coils because superconductors can conduct electricity without resistance and without producing heat.

So if the electromagnets in a MRI scanner are made of superconductors then you wouldn't be able to connect them to a power supply because having 0 resistance they would short the power supply out. Either superconductors do not have 0 resistance or you would have to put a very high power resistor in series with the windings to prevent the national grid being shorted out.


So if the resistance of these 'superconductors' is not 0 there has to be a voltage present and hence power is being drawn from the magnet.

It's like saying you need a voltage to keep an electron flying through the vacuum of space (which you don't).

But you have to apply a force to get it moving in the first place wether that be an actual physical push or by using an electric / magnetic field to attract or repel the electron.

The fact that the electron keep moving is due to the frictionles nature of the vacuum environment it's in.

 

[Rich Lyon]

You could suspend a very large electro-magnet a great distance in the air (say, a mile or so up, possibly suspended from a geostationary satellite by a thin, strong cable). Then place another magnet on the ground directly beneath it.

The motion of the earth through the solar electric field will create a current between the magnets, which can be captured. Any current net of that required to drive the electromagnets would be "free" energy, albeit a the cost of slowing the earth's orbital velocity.

 

[ICB]

Well, no, I wouldn't say that if I was the rope, because the human body consumes energy to maintain a position, grip hands etc. However, a tied up rope is just as inert as a pile of rocks. No energy being consumed or transformed anywhere.

I'm not trying to be some sort of smartarse by the way, these are pretty basic universal physics situations that are well-understood by science.

It's under strain isn't it? If you let it go quickly it's going to recoil somewhat, not quite the same as a pile of rocks.

The history of science is littered with examples of situations that were well-understood but were nevertheless later thoroughly revised, overthrown or subsumed within a new theory. I'm by no means saying this is true of you but IME some people with a deep scientific education often lack the philosophical one that allows them to see the difference between balance of probability and absolute truth or grasp that science is a matter of projection rather than revelation, a phenomenon of the human mind.

e.g. saying perpetual is forever rather than for a very long time. Nothing is forever in which case perpetual by this definition becomes a meaningless and useless concept. The orbit of our moon and the consequent motion of the tides (or the fusion of the sun and consequent radiation) is probably enough of a perpetual motion machine as far as our renewable energy needs are concerned.

 

[ICB]

You could suspend a very large electro-magnet a great distance in the air (say, a mile or so up, possibly suspended from a geostationary satellite by a thin, strong cable). Then place another magnet on the ground directly beneath it.

The motion of the earth through the solar electric field will create a current between the magnets, which can be captured. Any current net of that required to drive the electromagnets would be "free" energy, albeit a the cost of slowing the earth's orbital velocity.

I like it

 

[J77]

Rich Lyon - that idea is probably being thought of in terms of the space elevator (see science forum). Could be a good, so-called, power scavenging device.