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The question is pretty simple:

Can we build a device that coverts mechanical work in electric current1 without employing a permanent magnet and without access to any external source of current?

The restrictions in place seem to rule out the possibility of current generation via induction; and I cannot think of another practical method. I have heard that industrial alternators sometimes work with electromagnets, but we don't have access to any external source of current, so this path doesn't seem viable.

Do we really need stupid magnetic rocks to produce current? Unacceptable.


To be more specific and minimize to risk of misunderstandings: my question is more or less equivalent to the following one

Can we build a device, powered by hand via some sort of rotating lever, that produces electric current, crucially without employing any external current and without any permanent magnet?


[1]: Usable electric current, let's say sufficient to properly power up a lamp; doesn't matter if AC or DC.

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  • $\begingroup$ Can you be more specific on what your desired end result is? Why the restrictions? What are you trying to power? $\endgroup$ – David White Jun 7 at 16:57
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    $\begingroup$ If you find reliance on stupid magnetic rocks to be unacceptable, then why don't you have a problem with stupid conductive metals we need to use as wires? Whether there are pathways from mechanical work to electrical energy which don't explicitly utilize ferro/ferrimagnetic materials is a reasonable question, but loading it with disdain for naturally magnetic materials seems ridiculous - as though taking advantage of materials which are naturally sensitive to the "magnetic" part of electromagnetism is somehow primitive. $\endgroup$ – J. Murray Jun 8 at 18:35
  • $\begingroup$ This question looks stupid (my instructor used to say "I like stupid ideas"), but sometimes it can open new roads. I am curious to know the answer. $\endgroup$ – hsinghal Jun 12 at 16:34
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Doesn't a battery do this? Also, capacitors.

EDIT: With the edit, it looks like the premise of your question could be satisfied by a Van de Graff generator:

https://en.wikipedia.org/wiki/Van_de_Graaff_generator

which uses friction to strip electrons from a substance, and create an electrostatic potential.

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  • $\begingroup$ Sorry I forgotten one thing, will edit $\endgroup$ – Noumeno Jun 7 at 16:50
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    $\begingroup$ And solar cells. Solar cells might be a better answer depending on the intent of the OP. Is the question about the ultimate conversion of energy (sunlight, gravity, nuclear decay ...) or not. The question needs clarification. $\endgroup$ – garyp Jun 7 at 16:51
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    $\begingroup$ Fuel cells, RTGs (Radioisotope Thermoelectric Generator) ... $\endgroup$ – garyp Jun 7 at 16:54
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Piezo electric cells convert mechanical energy to electric energy

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You have a lot of ways to convert other forms of energy to electricity without permanent magnets, you might be using one right now, batteries, wich uses chemical energy (Unless it is recharged)

Here is a list of what i can think of:

  • Solar power
  • Chemical reactions (A good example for that is batteries)
  • Static electricity (Would be funny to see hydropower with a turbine spinning socks on carpets)
  • Lighting strikes
  • Atmospheric elctricity
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To answer this question one needs to think of a form of energy and then a device that will convert that energy into electrical energy.

Mechanical - Wimshurst machine, Van de Graaff generator, piezoelectric crystal, perhaps a self-exciting generator?

Light - Solar cell

Thermal - Thermocouple

Nuclear - Atomic battery

Sound - Contact microphone

Chemical - battery

Gravitational - via a mechanical device without a permanent magnet

In terms of lighting a bulb then a store of electrical energy, eg a capacitor, might be needed.

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You could use alternators with electromagnets, without a connection to the power grid by one of these means:

  1. Use solar panels to generate the current for the electromagnets.

  2. Use batteries to power the electromagnets, the batteries being charged using either solar panels and/or using a fraction of the power produced by the alternators.

  3. Instead of batteries, you could use super capacitors: https://www.sciencedirect.com/topics/chemistry/supercapacitors.

  4. Apparently in some car alternators, the residual magnetism (from the electromagnet's carcass) can be enough to bootstrap the process: https://electronics.stackexchange.com/questions/519621/source-of-initial-magnetic-field-in-an-alternator

The idea is to charge the super-capacitors with a fraction of the power generated by the wind turbine, and then use it to power the electromagnets in turn. Of course, batteries and/or solar panels are needed to "bootstrap" the system at startup if the capacitors have lost their charge.

In a car, sacrificing a part of the energy produced by the alternator in order to re-inject it (via the batteries) to power the electromagnets of the alternator is not an issue, because the source of power is the engine, itself powered by fuel.

If the aim is to generate electrical power using renewable energies in the most efficient manner possible, then doing without the electromagnets could prove counterproductive. A careful energy balance must be drawn in this case to try to assess if using electromagnets in place of permanent magnets is an overall benefit in terms of efficiency, in terms cost, in terms of ecological impact, etc.

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  • $\begingroup$ Super capacitors are a store rather than a source. $\endgroup$ – Farcher Jun 17 at 15:11
  • $\begingroup$ Yes, obviously : The idea is to charge the super-capacitors with a fraction of the power generated by the wind turbine, and then use it to power the electromagnets in turn. Of course, batteries and/or solar panels are needed to "bootstrap" the system at startup if the capacitors have lost their charge. $\endgroup$ – Serge Hulne Jun 17 at 15:28

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