Can Earth's rotation generate power? Physicists divided over controversial claim
220 comments
·March 30, 2025sroussey
The Earths rotation already generates power for us: wind. It’s why the jet stream only goes one direction.
kurthr
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.
kadoban
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.
vikingerik
Thermodynamically speaking, the energy in tides does come from Earth's rotation.
The moon raises a bulge in Earth's crust and ocean. Earth's rotation carries that bulge ahead of the Moon's position. The bulge pulls the Moon forward (raising it to a higher orbit), while the Moon pulls the bulge backward (slowing Earth's rotation.)
Once Earth's rotation slows enough, tidal lock is reached. Then the tidal bulge stays in a single place always pointed at the relatively non-moving overhead Moon, and there is no motion to extract energy from.
bmm6o
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.
peterashford
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
rokkamokka
While true, if the earth stopped rotating the sun would also stop being "evenly" distributed around the globe, which would affect wind patterns a lot
aaron695
[dead]
fsckboy
a substantial amount of wind is also caused by (differential) solar heating: that's why wind doesn't only go in one direction
if you've ever spent time at the seashore, the wind comes in off the sea during the day (because of rising thermals on the land side) and blows back offshore at night (because the land cools and the sea is now warmer) that time in between the air is dead-still, and that's when the swarms of gnats can find you.
veqq
But the earth's rotation makes the solar heating _differential_
triceratops
If the earth didn't rotate the differential would be permanent...and permanently in one direction
babyent
Is it possible to speed up the wind?
jcgrillo
Yes that's how airplanes work
_dain_
Yes, run power to wind turbines to use them as giant fans
righthand
Sure, cause constant heating and cooling and loop it.
timewizard
> It’s why the jet stream only goes one direction
Yet local winds blow in almost every direction. So to access that energy you'd need a structure 5 miles tall.
thayne
Or a balloon or kite five miles up.
IncreasePosts
Isn't that more of the sun+rotation?
cma
Foucault's pendulum also orbits in one way, but is that generating more power than put into it by starting it off?
bhk
None of the power comes from the Earth's rotation. Angular momentum is conserved in a closed system.
dang
The paper is here: https://arxiv.org/abs/2503.15790
(via https://news.ycombinator.com/item?id=43520716, but we merged that thread hither)
ziofill
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)
MathMonkeyMan
This is addressed in the last paragraph of the article:
> Even if it works, the method will not generate energy from thin air. It would tap Earth’s kinetic energy and, in doing so, cause the planet’s spinning to slow over time — although only slightly. If the technique provided all of Earth’s electricity needs, which was around 11 trillion watts in 2022, this would slow the planet’s spin by 7 milliseconds over the next century, the authors calculate. This is similar to the change in speed caused by natural phenomena such as the Moon’s pull and changing dynamics inside the planet’s core.
aeternum
Isn't friction from the atmosphere already slowing the planet's spin? Many weather effects like hurricanes ultimately derive their energy from a combination of the earth's rotation and thermal/uneven heating effects so I don't see why this is contentions.
Like most things, nature is already doing it and has been for millions of years.
mr_mitm
No, that's not possible due to conservation of angular momentum. Only tidal effects can transfer some of it to the sun.
mmooss
How much velocity loss would be needed for an impact on the environment, or on some humans someplace?
api
> which was around 11 trillion watts in 2022, this would slow the planet’s spin by 7 milliseconds over the next century, the authors calculate.
Really puts how small we are on a cosmic scale into perspective.
If we did it for a million years at current energy use scale it would shorten our day by about 1.1 seconds.
OccamsMirror
Wouldn't it extend our day?
thayne
Where does the angular momentum go?
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ForHackernews
It's kind of insane how much energy is involved in big masses of rock flying around in space.
DriverDaily
Can we put energy in to speed it up?
That way a day can be 24 hours exactly instead of 23 hours, 56 minutes, 4 seconds, etc...
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incognito124
I mean, solar day is 24h, it's the sidereal day that's 23.9344696h
Detrytus
Don’t follow your logic: if the day is currently shorter than 24 hours we need to slow the Earth rotation down, not speed it up.
frozencooler
Doesn’t driving west to east on a highway slow down the Earth’s rotation, via the power transferred into the ground?
rocqua
It's actually driving north south that changes the rotation speed. Because your 'real' speed gets higher as you get closer to the equator, you 'steal' momentum from the earth as you get closer to the equator.
Its effectively the same principle as a figure skater pulling in their arms when spinning, to spin faster.
logifail
Reminds me of a glorious question from undergraduate physics:
Calculate the change in the length of the Earth's day if the UK were to switch to vehicles driving on the right-hand side of the road rather than the left..
antod
Is that due to all the roundabouts switching direction relative to the Coriolis effect? Hence the relevance of the UK?
Presumably without roundabouts it's all random directions and balanced?
Or am I barking up the wrong tree?
amarant
Yes, but that energy is returned when you break
danillonunes
Things get interesting when you reverse.
thayne
Then when you stop the angular momentum of your car is transferred back to the earth.
BurningFrog
Only while you're driving.
Retric
0.44 picowatts = 4.4e-13 watts so not in a detectable fashion before the sun consumes the earth billions of years from now.
ziofill
Well, the watts that come out of the rotational energy must match the ones we need, for energy conservation.
Retric
Sure, but there’s no “eventually” it happens instantly.
The only way you’ll care about what happens eventually is if you’re concerned about some detectable result. Meanwhile individual rocket launches to Mars extract like 10^18+ times as much energy as this will over it’s lifespan and those still aren’t detectable.
golol
Where does the angular momentum go?
fsckboy
it's the angular momentum that gets transferred to the earth's spin, and all the other numbers, energy, power, are simply how the books are balanced. GP should have asked the question in terms of momentum in the first place.
with energy, you need to consider friction, losses, thermodynamics 3rd law, but with momentum it's pure.
teamonkey
Torque is applied, the paper mentions a magnetic braking effect.
foota
The IERS will never stand for this!
themaninthedark
There was a decent science fiction serris based on this premise:
https://www.goodreads.com/book/show/700919.Signal_to_Noise
https://www.goodreads.com/book/show/737628.A_Signal_Shattere...
watersb
Ideally enjoyed these. Can't find them as ebooks.
The first one was where I first encountered the idea of the "One Electron Universe":
https://en.m.wikipedia.org/wiki/One-electron_universe
A major plot point of these books is an alien technology that enables teleportation by somehow tapping into the Earth's angular momentum.
jaggederest
Eric Nylund's books are uniformly excellent, even (perhaps surprisingly) the Halo tie-ins
genewitch
Never heard of him
genewitch
> The novel follows Jack Potter, a computer cryptographer tenured at the fictional Academe of Pure and Applied Sciences in Santa Sierra, California (a city assembled from the ruins of San Francisco.) The story details Jack's first encounter with an alien calling himself Wheeler who apparently wishes to trade information with humanity.
> Accompanied (for a while) by "gene witch" Zero al Qaseem and data paleontologist Isabel Mirabeau, Jack establishes a corporation based around one of the technologies he was traded by Wheeler, but soon finds that there may be more to his dealings with the alien than he bargained for. Traitorous alliances, deceitful propaganda, and shady business practices are frequent elements of the novel.
> "gene witch"
genewitch
"Decent"
pavel_lishin
I thoroughly enjoyed them! I think I have both in paperback, though as a teenager, I managed to read them out of order.
vessenes
This is really cool. Question for EEs / Material Scientists reading the paper - they mention you could shrink the cylinders and get the same voltage provided a "suitable material" could be found. Any back of the envelope or explanation of materials needed to make these cylinders say 1/1000th their current size? That'd be an extremely useful amount of energy when put into say a 1000x parallel array.
It seems hard to imagine that this kind of shrink-down could go on forever, but on the other hand, the earth is just sort of hurtling us around with great energy while it rotates.
LegionMammal978
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.
api
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 to heat food. They appear to have realized this."
Certhas
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...
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qnleigh
Well conservation of energy says you can't extract energy out of nowhere. In the paper they claim that the extracted energy comes at the price of slowing down Earth's rotation. But then this seems to violate conservation of angular momentum... Maybe it depletes Earth's magnetic field instead?
sitharus
Conservation of angular momentum doesn’t prohibit reducing angular momentum by extracting energy, in this case the angular momentum is converted to electricity.
1970-01-01
A bad question, as it has been doing that literally (rotationally) since before life started. This power is busy generating the magnetosphere. We would not be enjoying our nice oxygen atmosphere and would be as dead as Mars if Earth's rotation wasn't also powering a dynamo.
mr_mitm
It doesn't take any energy to maintain a static magnetic field though.
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pfdietz
The currents that produce the magnetic field are flowing in liquid metal with nonzero resistivity.
fallingknife
Earth's rotation is also generating the power that is moving the Moon's orbit slowly away from Earth. There will be no more total solar eclipses in 600 million years because of this.
ChrisNorstrom
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?
ChuckMcM
It isn't a stupid question, it is a good one. The answer would depend on how the field is generated in the first place.
Given a field generated by asymmetric rotation of the molten core at the center of the Earth, 'shorting it' (apply a load) would presumably affect the core's rotation. In terms of relative energy however, the poor coupling at the surface would suggest that this would be a very challenging way to divert any meaningful amount of power from the core itself. It would however have to deal with points in time where the core reverses its magnetic field. The papers on core reversals are fun to read.
I think more usefully, the presence of the voltage, might be an interesting way to localize one's location and orientation.
I remember brainstorming "off the wall" power generation ideas and one that has yet to be realized would be to inject dust ahead of a wind turbine with a collector in the back. Then using the Van DeGraf effect to generate power instead of lightning as it currently does.
fpoling
If one needs location, then the magnetic field can be measured directly. It is already considered as a potential alternative for GPS, https://www.electronicdesign.com/markets/automation/article/...
The main problem is that locally measured Earth magnetic field varies on a daily basis and is strongly influenced by solar storms.
A better alternative is to use variations in Earth gravity to improve inertial navigation. That vastly more stable.
whatshisface
They are one step ahead of you. :-)
"We previously showed that even in an extreme scenario where our civilization somehow would obtain all its electrical energy from the effect described here, Earth’s rotation would slow by <1 ms per decade [2]."
ngruhn
fast forward a hundert years and there is a massive culture war between the "rotation slowdown deniers" and people religiously buying "rotation friendly" products.
marshray
The term "generate power from Earth's rotation" is basically saying "convert kinetic energy from Earth's angular momentum". If you extract energy, by conservation of energy that energy has to come from somewhere. So yes, we would normally expect Earth's rotation to slow.
But I think if you do the math, it would be absolutely miniscule.
6510
I'm not saying that is why we left Mars.
aeve890
Yeah, after making an oopsie with a runaway greenhouse effect in Venus. All this has happened before and it will happen again.
amarant
Ah yes, the Battlestar Galactica theory of life's origins on earth
fallingknife
It's definitely not why we left Mars because Mars still rotates every 24:30. We left Mars because of the hostile Martians, of course.
nopelynopington
I've often wondered about a similar issue with wind power. Would enough wind turbines dampen the force of wind?
padjo
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.
bee_rider
Fundamentally, yes, right? For some definition of “enough.”
Actually, after some quick googling (so, maybe someone actually knows better) it seems like this is an issue where there’s an active discussion? Maybe somebody actually involved in the field knows more.
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2004JD00...
https://esd.copernicus.org/articles/3/79/2012/esd-3-79-2012....
But that came out in 2012. I bet you could find some other article citing it, as rebuttals.
It seems a bit implausible to think we could somehow pull enough energy from the wind to really matter, but then again carbon based climate change also seemed a bit implausible so, I guess, who knows?
nprateem
If a politician talks in front of a wind turbine, does it make a sound?
modeless
Alternatively, we could speed up the Earth! Let's get rid of those pesky leap seconds!
chrisjj
> would that accidentally slow the Earth's rotation
No. Incidentally :)
threeseed
Current = 25.4 ± 1.5 nA, Voltage = 17.3 ± 1.5 µV.
Making total power for the 30cm shell = 0.44 picowatts.
MichaelRo
[flagged]
serm56
I don't see a problem with the LLM answer. The field near an FM station can reach 100mV or more. The maximum safe exposure levels for general public at 100MHz is 30V/m according to standards.
rcxdude
It's easy to lose a sense of scale in a field which usually works in logarithmic scales. Signals can easily vary by more than 40dB, and it's easy to forget that's a factor of 100 already, and another 40-60dB is not crazy in edge cases. (OTOH ~100uV is a much better estimate of what you'll be seeing from a 'good' FM radio signal)
userbinator
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.
MichaelRo
Well, I'm expecting an average case, not "playing AM radio with grass", because in the vast majority of the cases, antennas won't be situated within a few meters of the radio tower:
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Kerbonut
I had an idea somewhat related to this where we use the solar winds as a sort of road and the earth's magnetic field as a sort of rotor to convert kinetic energy from the sun into electricity.
BurningFrog
This kinda sorta how auroras/northern lights work.
evan_
Sounds like solar power with extra steps
null
https://archive.is/5GHWF