The Earths rotation already generates power for us: wind. It’s why the jet stream only goes one direction.
Foucault's pendulum also orbits in one way, but is that generating more power than put into it by starting it off?
Can Earth's rotation generate power? Physicists divided over controversial claim
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Re: Can Earth's rotation generate power? Physicists divided over controversial claim
#102I wonder how many wats of power we would be able to generate before earth slows down for i.e. 1 second longer day.
I'm taking figures from https://en.wikipedia.org/wiki/Rotational_energy
Moment of inertia of the Earth: I=8.04e37
Angular velocity, with sidereal rotation period of 23.93 hours: ω0=2π/(23.93 × 3600)
Angular velocity, with sidereal rotation period of 23.93 hours plus one second: ω1=2π/(23.93 × 3600 + 1)
Rotational energy difference: .5 × I × ω0 ** 2 - .5 × I × ω1 ** 2 ≈ 4.96e+24 J
For comparison, according to https://ourworldindata.org/energy-production-consumption the total amount of energy consumed on Earth in 2023 was 180E3 TWh i.e. 6.48e+20 J
Slowing down the Earth by one second would be equivalent to 7661 times this amount.
Re: Can Earth's rotation generate power? Physicists divided over controversial claim
#103Wouldn'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)
Doesn’t driving west to east on a highway slow down the Earth’s rotation, via the power transferred into the ground?
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.
Re: Can Earth's rotation generate power? Physicists divided over controversial claim
#104Imagine a massive planet spinning in empty vacuum. Can the inhabitants slow down their planet, and generate electricity? I suspect that they can generate electricity with angular momentum with it, that can be only used to do work with the equivalent angular momentum.
The Moon's tidal forces are already slowing down the rotation period of the Earth, which was apparently only 5 hours long about 4.5 billion years ago.
Re: Can Earth's rotation generate power? Physicists divided over controversial claim
#105The 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.
Re: Can Earth's rotation generate power? Physicists divided over controversial claim
#106I wonder how many wats of power we would be able to generate before earth slows down for i.e. 1 second longer day.
According to Wikipedia [1] we consume 9717 Mtoe or equivalently 408 TJ (per year, although it is not explictely stated, which I find annoying).
The earth moment of inertia is about I=8e37 kg m2 [2]
The energy extracted by a slowdown of angular speed from wa to wb would be 1/2 I(wa2-wb2).
Approx wa=2pi/86400 and wb=2pi/86401. Energy extracted: 4.9e24J=4.9e12TJ.
We would have energy for about 12 billion years.
If I double check with Kagi's assistant with Claude 3.7 (I'm in my phone and I could easily have made an error) it starts with my exact reasoning and figures but messes up final numbers (so close!!!) to give a total of 40 billion years, which nevertheless is the correct order of magnitude.
[1] https://en.m.wikipedia.org/wiki/World_energy_supply_and_cons...
[2] https://scienceworld.wolfram.com/physics/MomentofInertiaEart...
Re: Can Earth's rotation generate power? Physicists divided over controversial claim
#107Earlier quoted context omitted.
The Navy isn’t constrained by economics. Nuclear doesn’t make sense economically compared to things like solar and batteries.
> things like solar and batteries. Magnets too - let's just go magnets everywhere. Reality is solar isn't viable everywhere. And it's not optimal to put it in places where you use the sun to grow food. We should follow a holistic approach. * Wind where it's windy. * Solar where it's sunny - ideally on buildings/away from farms. * Hydro where possible. * Nuclear where it makes sense, i.e. stable geography, low occuren…
Why doesn't Geothermal make your list?
Re: Can Earth's rotation generate power? Physicists divided over controversial claim
#108It's incredible the lengths humanity is willing to go to avoid adopting nuclear energy - despite the US navy driving mobile reactors millions of miles over the last 70 years.
Solve the waste problem and you solve nuclear. Waste is still the giant elephant in the room and a lot of people have a fifth grade solution to the problem (we will bury it under ground! We will fly it to the sun! We will resuse it until it is no longer radioactive!) I used to have a neighbor who worked for the DOE, all of the viable solutions are blocked by people who don’t want it in their backyard. Can’t really mo…
> Waste is still the giant elephant in the room and a lot of people have a fifth grade solution to the problem (we will bury it under ground! We will fly it to the sun! We will resuse it until it is no longer radioactive!)
The correct solution: put it into dry casks and do nothing right now. Store it simple underground storage facilities or on the grounds of active nuclear power plants.
The casks are fine for the next 300 years, and during that time we can either:
1. Perfect the nuclear fusion, it will provide plenty of neutrons to transmute the waste.
2. Perfect fast fission reactors. See above.
3. Use some of the excess of too-cheap-to-meter green energy for accelerator-driven subcritical fission reactors.
4. Yep, use rockets to slowly launch the waste into space. We can already design a storage capsule that can survive re-entry.
In any case, we have literally hundreds of years to come up with a solution and there are many viable paths.
Re: Can Earth's rotation generate power? Physicists divided over controversial claim
#109It's incredible the lengths humanity is willing to go to avoid adopting nuclear energy - despite the US navy driving mobile reactors millions of miles over the last 70 years.
The Navy isn’t constrained by economics. Nuclear doesn’t make sense economically compared to things like solar and batteries.
Why do we have to be constrained by economics unlike the navy? The state within the state has access to nuclear powered ships so it is just a question of widening that capability to the members of the state living outside the walls of the keep. Not a matter of establishing precedent or anything. That part is done and long proven. The federal government even has experience managing water and power for entire geographical regions today.
Re: Can Earth's rotation generate power? Physicists divided over controversial claim
#110It's incredible the lengths humanity is willing to go to avoid adopting nuclear energy - despite the US navy driving mobile reactors millions of miles over the last 70 years.
Solve the waste problem and you solve nuclear. Waste is still the giant elephant in the room and a lot of people have a fifth grade solution to the problem (we will bury it under ground! We will fly it to the sun! We will resuse it until it is no longer radioactive!) I used to have a neighbor who worked for the DOE, all of the viable solutions are blocked by people who don’t want it in their backyard. Can’t really mo…
What problem with the waste? Reactors are working and generating power today for many thousands of americans. Whatever is being done with waste today seems to work well enough to continue reactor operations without any major headlines. Just seems to be a bit of cognitive dissonance here between what is claimed online and what we see today out in the field generating power.