[evan_au (OP)]

Linda asks: Can the spinning of the Earth be used as a source of electricity, similar to the spinning of wind turbines?

[evan_au (OP)]

The Earth spinning does set up electric currents in liquid iron in the outer core of the Earth. This generates the Earth's magnetic field, which shields our atmosphere from the solar wind.
https://en.wikipedia.org/wiki/Earth%27s_magnetic_field#Physical_origin

Some satellites have tested the use of an electrodynamic tether, which uses the Earth's magnetic field to generate electricity and/or generate thrust.
See: https://en.wikipedia.org/wiki/Electrodynamic_tether

[evan_au (OP)]

Less directly, the spinning of the Earth interacts with the gravitational pull of the Sun and Moon to generate ocean tides, and the tidal currents can be used to generate electricity.
https://en.wikipedia.org/wiki/Tidal_power

[paul cotter]

generally you need a changing magnetic field or a conductor moving through a magnetic field gradient to generate. there are types that do not adhere to this "axiom" such as the homopolar disc generator but still involve motion of a conductor, for which torque has to be supplied. the earth's magnetic field is unchanging in the short run and hence will not enable power generation on the surface(i.e. not including tether arrangements). hope that's coherent and correct-didn't sleep well last night!

[evan_au (OP)]

the earth's magnetic field is unchanging in the short run

This is true most of the time, but when a Coronal Mass Ejection (CME) from the Sun strikes the Earth, this can cause much more rapid changes in the Earth's magnetic field (on the order of seconds and minutes).

This induces large currents in metal conductors such as power lines and oil pipelines. These are undesirable electric currents, at DC or very low frequencies (below 1Hz):
- Power transformers have a magnetic saturation characteristic that is proportional to 1/frequency. They normally operate at 50Hz or 60Hz (depending on the country), but when they get hit by a current of (say) 0.01Hz, the iron core saturates and the transformer effectively becomes a short-circuit. Such an event took out power in Quebec in 1989.
- I recall a story that an oil pipeline had been measured carrying 30,000 Amps of current. High currents, oil and potential sparks are not a good combination!

See: https://en.wikipedia.org/wiki/March_1989_geomagnetic_storm
 https://en.wikipedia.org/wiki/Geomagnetic_storm#Geomagnetic_storm_effects

[wolfekeeper]

Linda asks: Can the spinning of the Earth be used as a source of electricity, similar to the spinning of wind turbines?

The spinning of the Earth itself can't be the source of electricity, since the Earth has to conform with conservation of angular momentum. Unless something left the Earth or joined the Earth or another external body changed speed, or the Earth radically changed shape, no closed cycle can result in the Earth simply slowing down and electricity being generated, as it will always have the same angular momentum.

[gem]

Hi all,

So wolfekeeper you raise an important contradiction to evan_au posts.

Less directly, the spinning of the Earth interacts with the gravitational pull of the Sun and Moon to generate ocean tides, and the tidal currents can be used to generate electricity.

No water is pumped up in the suns and moons gravitational field and no friction occurs as the solid Earth rotates passed these bulges ?

The Earth spinning does set up electric currents in liquid iron in the outer core of the Earth. This generates the Earth's magnetic field, which shields our atmosphere from the solar wind.

what powers this generation of electro magnetic currents ? and how is it isolated from placing a load on the rotation of Earth ?
 

[paul cotter]

Trying to develop energy from the mechanical rotation of the earth would involve insurmountable difficulties despite being theoretically possible.An isolated structure that is static with reference to the rotating earth or rotating with a shorter or longer period than the earth would be required first. then this structure would be required to follow the track of the earth around the sun.Not at all practical and i'm sure there could be other difficulties involved.

[gem]

Hi all

Trying to develop energy from the mechanical rotation of the earth would involve insurmountable difficulties despite being theoretically possible.An isolated structure that is static with reference to the rotating earth or rotating with a shorter or longer period than the earth would be required first. then this structure would be required to follow the track of the earth around the sun.Not at all practical and i'm sure there could be other difficulties involved.

Does the tidal bulge not satisfy those requirements ?

If so its pretty straight forward and is already being done.

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


Also the tidal effects due to the Moon are greater than due to the Sun

http://hyperphysics.phy-astr.gsu.edu/hbase/tide.html#:~:text=Go%20Back-,Sun's%20Tidal%20Effect,gravity%20field%20across%20the%20Earth.

[Bored chemist]

Unless something left the Earth or joined the Earth or another external body changed speed,

The moon changes speed, so that's OK.
It is important to realise that you can't extract the energy unless you have something to push or pull against.
Once you realise that the Sun and Moon fit the bill, you can understand how tidal power works.

Trying to develop energy from the mechanical rotation of the earth would involve insurmountable difficulties despite being theoretically possible.

We are doing it.
https://en.wikipedia.org/wiki/Tidal_power

[evan_au (OP)]

what powers this generation of electro magnetic currents ?

It is thought to be the slow cooling of the earth's core:
- Gravitational energy is released as denser elements sink and lighter elements rise in the outer core (perhaps excluded by the crystal structure of the inner core?)
- Heat is released when liquid iron & nickel turns into a mushy/solid at the boundary of the Earth's inner & outer core (it is thought that the radius of this boundary grows at around 1 mm per year)
- additional heat is released by the decay of radioactive elements like Uranium and Thorium
- Some have even recently speculated (based on seismology) that the remnants of Theia's core are still sinking to coalesce with the Earth's core
- This causes convection currents in the outer core
- This interacts with the rotation of the Earth to generate electric currents in the outer core, which generates the Earth's magnetic field
See:  https://en.wikipedia.org/wiki/Earth%27s_outer_core#Implications_for_Earth's_magnetic_field

[gem]

Hi all

Thanks for that Evan, my bold

- Some have even recently speculated (based on seismology) that the remnants of Theia's core are still sinking to coalesce with the Earth's core
- This causes convection currents in the outer core
- This interacts with the rotation of the Earth to generate electric currents in the outer core, which generates the Earth's magnetic field

As you state there is still a lot of speculation in this regard, and some of the modeling being done is even testing the capacity of super computers.
But there are some fundamentals required in these models

eg,   conversion of kinetic energy to magnetic energy, and a requisite is part of the Kinetic energy is provided by planetary rotation.

So the point raised by wolfekeeper remains.

Along with the similarity to the work heat equivalence experiments of Joule, we can observe as the friction with local geography of the solid earth passes/interacts with these tidal bulges, due to its rotation.