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

nature.com

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

#111

Post by kadoban »

kurthr wrote: post #105
sroussey wrote: post #86

The Earths rotation already generates power for us: wind. It’s why the jet stream only goes one direction.

And don't forget the tides, both solar and lunar. I'm sure a large enough mirror and photocell could get power out of the aurora borealis. An argument that the magnetic field in a location remains completely constant as the earth rotates seems bizarre, but so does the idea that it's large enough to economically extract power.

Are the tides caused by Earth's rotation? My understanding is they're not.

I know they're a bit of an inter-related system, but I thought if anything tides mess with rotation (eventually causing tidal lock), not so much the other way around.

How big are the solar tides? Never really considered that tbh. Looked it up, they're about half the size of the Lunar ones? Wild.

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

#114

Post by bmm6o »

kadoban wrote: post #111
kurthr wrote: post #105

Earlier quoted context omitted.

And don't forget the tides, both solar and lunar. I'm sure a large enough mirror and photocell could get power out of the aurora borealis. An argument that the magnetic field in a location remains completely constant as the earth rotates seems bizarre, but so does the idea that it's large enough to economically extract power.

Are the tides caused by Earth's rotation? My understanding is they're not. I know they're a bit of an inter-related system, but I thought if anything tides mess with rotation (eventually causing tidal lock), not so much the other way around. How big are the solar tides? Never really considered that tbh. Looked it up, they're about half the size of the Lunar ones? Wild.

The short answer is that there would still be tides without rotation, but with a period based on the lunar cycle. We have daily tidal effects, the moon can't do that by itself.

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

#115

Post by Hyperboreanal »

Rygian wrote: post #73
deadbabe wrote: post #69

Suggest a hard sci-fi story where humans abuse this so much the Earth basically stops rotating.

I've already read one where some weird alien ants hollow out the earth to make it spin faster, and take advantage of the increase in speed to generate power somehow (maybe by building a geostationary conductive belt around the planet, that acts as the "stator"?)

Saying what book you're talking about is kind of a spoiler now for anyone that happens to be reading its series. Are there spoiler tags on HN? The Long Utopia, book 4/5 of the Long Earth series by Pratchett and Baxter. The series has very meh characters/dialogue, excellent ideas and sense of nearly possibility-unlimited discovery that's executed very well, highly recommend if that's your cup of tea. Ended up skipping all the flashback chapters near the end of the series though, that felt like a load of filler

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

#117

Post by righthand »

babyent wrote: post #116
sroussey wrote: post #86

The Earths rotation already generates power for us: wind. It’s why the jet stream only goes one direction.

Is it possible to speed up the wind?

Sure, cause constant heating and cooling and loop it.

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

#118

Post by ada1981 »

Beijinger wrote: post #83
IshKebab wrote: post #65

Earlier quoted context omitted.

That's easy to work out but I can tell you not it's going to be more than we will ever use.

You have no idea, what amount of energy we will be able to use the long run.

220, 221, whatever it takes.

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

#119

Post by Certhas »

api wrote: post #84
LegionMammal978 wrote: post #82

It would be interesting if this works. Last time people were hyping up a tiny effect with big ramifications that can only exist due to a subtle 'loophole', it was the EmDrive stuff that turned out to be driven by measurement errors. But I'm no expert in electrostatics.

I was about 99.99999% sure that one was bogus because it was violating bedrock conservation laws. I'm not sure that this does. AFAIK there is no conservation law that says a spinning mass can't extract power from that. Still... it would have been hilarious of the EmDrive had worked. "Well, they've progressed! Last time we checked in on the third planet in this star system its inhabitants were still using warp drives…

For the EmDrive it also was that the claimed theoretical mechanism was mathematically impossible, because it was based on equations that (like all known equations and everything ever observed) satisfy the conservation laws.

That's a good question actually. Supposedly this is extracting energy from the rotational kinetic energy of the earth. I haven't looked at the paper but you'd need to worry about conservation of angular momentum here.

Given that the cited physicists didn't dismiss this out of hand I assume this is accounted for somewhere...

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

#120

Post by peterashford »

sroussey wrote: post #86

The Earths rotation already generates power for us: wind. It’s why the jet stream only goes one direction.

Wind power is mostly due to solar energy. Earth's rotation contributes a very small amount and even that smaller effect is more located in the upper atmosphere where we don't collect wind power versus solar caused pressure gradients
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