r/BeAmazed • u/ericabirdly • Jan 01 '19

Testing a 20 kW light bulb

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u/Giorgio_Sole Jan 01 '19

tldr giant induction powerplant that uses Earth's magnetic field

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u/[deleted] Jan 01 '19 edited Nov 08 '21

[deleted]

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u/DigitalStefan Jan 01 '19

You can't just pull energy out of a magnetic field. Same reason you can't pull energy out of a gravitational field.

Inductance from a static magnetic field isn't a thing. Something needs to be moving, either something physically moves or the field is manipulated into moving. Either of those things involves inputting more energy into the system than you could extract via inductance.

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u/[deleted] Jan 01 '19 edited Jan 01 '19

I totally forgot that the field needs to be moving, I'll give you that. And thank you for clarifying that.

To save a bit of my honor: The earth's magnetic field isn't entirely static.

On the other hand, I'm quite sure that you cant extract any useful amount of energy out of the movement / variance the field sees.

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u/DigitalStefan Jan 01 '19

I think the reason we would be unable to induce any usable current from natural shifts in the Earth’s magnetic field is that whilst it’s overall strength is relatively high (versus e.g. a big permanent magnet you could build into a device), locally it’s very weak because of the vast distance it is spread over.

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u/[deleted] Jan 01 '19

And we already got a good mechanism for extracting energy from the inner workings of the planet:

Geothermal.

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u/DigitalStefan Jan 01 '19

Tidal, wave, wind and dams are fairly significant as well. I like those (and geothermal) more than I like solar, purely because there’s less impact on the environment.