Can Earth's rotation generate power? Physicists divided over controversial claim • Hacker News Board

Re: Can Earth's rotation generate power? Physicists divided over controversial claim

#21

Post by aeve890 » Sun, Mar 30, 2025, 7:50 AM UTC

6510 wrote: post #4

ChrisNorstrom wrote: post #3

My Stupid Question, please don't laugh: If you did this on a massive enough scale, to generate serious amounts of power, would that accidentally slow the Earth's rotation down over time?

I'm not saying that is why we left Mars.

Yeah, after making an oopsie with a runaway greenhouse effect in Venus. All this has happened before and it will happen again.

Re: Can Earth's rotation generate power? Physicists divided over controversial claim

#22

Post by userbinator » Sun, Mar 30, 2025, 8:02 AM UTC

MichaelRo wrote: post #6

threeseed wrote: post #2

Current = 25.4 ± 1.5 nA, Voltage = 17.3 ± 1.5 µV. Making total power for the 30cm shell = 0.44 picowatts.

[flagged]

The part about FM sounds like BS, but much more than 1V at the antenna is definitely possible if you're close to an AM station, enough to cause unintentional receivers to emit sounds.

Re: Can Earth's rotation generate power? Physicists divided over controversial claim

#23

Post by nopelynopington » Sun, Mar 30, 2025, 8:10 AM UTC

ChrisNorstrom wrote: post #3

My Stupid Question, please don't laugh: If you did this on a massive enough scale, to generate serious amounts of power, would that accidentally slow the Earth's rotation down over time?

I've often wondered about a similar issue with wind power. Would enough wind turbines dampen the force of wind?

Re: Can Earth's rotation generate power? Physicists divided over controversial claim

#24

Post by nprateem » Sun, Mar 30, 2025, 8:37 AM UTC

nopelynopington wrote: post #23

ChrisNorstrom wrote: post #3

My Stupid Question, please don't laugh: If you did this on a massive enough scale, to generate serious amounts of power, would that accidentally slow the Earth's rotation down over time?

I've often wondered about a similar issue with wind power. Would enough wind turbines dampen the force of wind?

If a politician talks in front of a wind turbine, does it make a sound?

Re: Can Earth's rotation generate power? Physicists divided over controversial claim

#25

Post by ziofill » Sun, Mar 30, 2025, 8:44 AM UTC

Wouldn't this eventually slow down Earth's rotation? The rotational kinetic energy of our planet is 1/5 M * R^2 * w^2 with (approximately) M = 6e34 kg, R = 6.3e6m, w = 7.4e-5 rad/s, which gives approximately 5e36 joules. Yearly we need roughly 3e16 Wh. Yeah ok there's plenty. Woah! (also, I may be off by some orders of magnitude)

Re: Can Earth's rotation generate power? Physicists divided over controversial claim

#26

Post by ziofill » Sun, Mar 30, 2025, 8:45 AM UTC

ninetyninenine wrote: post #20

Wouldn't this slowly slow the earths rotation down? Let's say everyone tried to build power plants using this.

Ah didn't see this comment and I asked the same. Yes, right? The energy has to come from somewhere...

Re: Can Earth's rotation generate power? Physicists divided over controversial claim

#27

Post by Retric » Sun, Mar 30, 2025, 8:45 AM UTC

ziofill wrote: post #25

Wouldn't this eventually slow down Earth's rotation? The rotational kinetic energy of our planet is 1/5 M * R^2 * w^2 with (approximately) M = 6e34 kg, R = 6.3e6m, w = 7.4e-5 rad/s, which gives approximately 5e36 joules. Yearly we need roughly 3e16 Wh. Yeah ok there's plenty. Woah! (also, I may be off by some orders of magnitude)

0.44 picowatts = 4.4e-13 watts so not in a detectable fashion before the sun consumes the earth billions of years from now.

Re: Can Earth's rotation generate power? Physicists divided over controversial claim

#28

Post by Retric » Sun, Mar 30, 2025, 8:50 AM UTC

cedws wrote: post #9

threeseed wrote: post #2

Current = 25.4 ± 1.5 nA, Voltage = 17.3 ± 1.5 µV. Making total power for the 30cm shell = 0.44 picowatts.

Still more net energy than fusion reactors have ever produced.

No, it took far more electricity to make than it produces over any conceivable lifetime.

Re: Can Earth's rotation generate power? Physicists divided over controversial claim

#29

Post by ziofill » Sun, Mar 30, 2025, 9:01 AM UTC

Retric wrote: post #27

ziofill wrote: post #25

Wouldn't this eventually slow down Earth's rotation? The rotational kinetic energy of our planet is 1/5 M * R^2 * w^2 with (approximately) M = 6e34 kg, R = 6.3e6m, w = 7.4e-5 rad/s, which gives approximately 5e36 joules. Yearly we need roughly 3e16 Wh. Yeah ok there's plenty. Woah! (also, I may be off by some orders of magnitude)

0.44 picowatts = 4.4e-13 watts so not in a detectable fashion before the sun consumes the earth billions of years from now.

Well, the watts that come out of the rotational energy must match the ones we need, for energy conservation.

Re: Can Earth's rotation generate power? Physicists divided over controversial claim

#30

Post by padjo » Sun, Mar 30, 2025, 9:03 AM UTC

nopelynopington wrote: post #23

ChrisNorstrom wrote: post #3

My Stupid Question, please don't laugh: If you did this on a massive enough scale, to generate serious amounts of power, would that accidentally slow the Earth's rotation down over time?

I've often wondered about a similar issue with wind power. Would enough wind turbines dampen the force of wind?

On a local level they absolutely do, in a wind farm one turbine can shadow another and reduce its output significantly. It makes wind farm layout a tricky optimisation problem. On larger scales the impact is pretty minimal though, there’s so much energy spread over such a large area that significantly reducing it a global scale is not a concern.