Other than construction, cost, logistics, all that stuff that actually matters. Say I was to construct a halo around the earth. A large hollow ring that goes across the equator. Inside this bring are big spheric balls which roll around and around, they are in essence in orbit around the earth but “trapped” in the inside of the ring. Now what if I had flippers or other similar mechanism to catch the kinetic energy of the balls and transfer that somewhere. I am not even going to bother with talking about storing/transfering energy. Would the balls eventually stop from friction from hitting the flippers or would the movement and gravity of the earth keep them going forever.
We have done this one before. I even thought of it myself and it won’t work. The balls won’t stay in orbit after they hit the flippers. A given orbit requires a certain speed to maintain and hitting the flippers will cause the balls to slow down and try to drop to a lower orbit but they can’t so they will just stop. If you stood inside the tube, it would look remarkably straight anyway because the curve is so slight and it would just seem the same as rolling a ball down a really long bowling alley with flippers in it. It is easy to imagine why the bowling ball would eventually stop as well but it is the same problem as a tube elevated off the ground no matter how high it is.
If you’re going to build that kind of infrastructure, though, it wouldn’t be too hard to make something that takes energy from the rotation of the Earth. That’s not free, either, since the Earth has a finite amount of rotational energy, but it’s an awful lot of energy.
I had read a while ago about the idea of having long metal cables with one end on the ground and the other in low earth orbit. I think the idea was that by passing through the earth’s magnetic field you would induce a current in the wire that could be harvested.
Honestly I don’t see how that would work, but apparently if we could make cables strong enough and get one end into orbit it’s supposed to be a sure thing. IDK.
A wire orbiting the earth passing through the earth’s magnetic field will generate a voltage potential, same as a loop of wire in a generator. And just like the loop of wire in the generator, drawing current from the wire in orbit will generate a reaction force in opposition to the wire’s movement. That will cause drag, which will cause the wire to fall out of orbit. Conservation of energy is inescapable - if you’re getting energy out of the system, it’s going to run down eventually.
Which means that, ultimately, you’re getting the energy from the rocket fuel that you used to launch the satellite. Which is a hugely inefficient way of generating electricity.
Any reason it would only work one way, though?
Because in this house we obey the laws of thermodynamics!
As in, you want to use some other energy source to bring the Earth’s rotation back up? Sure, you could do that.
That is a great idea. Quit your job, sell everything you own to seed the start-up costs. I’m sure you will have no trouble attracting investors once you get the ball rolling. Don’t forget to file with the patent office. Keep us informed of your progress. Don’t worry about slowing down the rotation of the Earth. Haven’t you heard people complaing about how there aren’t enough hours in the day? Well you’ve found a way of adding more hours. People will be grateful.
Not necessarily.
If you had a space elevator of some sort, you could mine ballasts and shoot them toward the elevator pretty efficiently, and as the cable starts bending from generating electric force, along comes a ballast which gets somehow exchanged (mere engineering details), rocking the cable back “forwards” where it again slows and the cycle repeats. The old chuck of rock can be used to blow stuff up on the ground, or shattered and allowed to burn up, etc. Then you are collecting energy from the sun’s gravitational potential if you do the mechanics right.
Bonus points if you throw comets from the oort cloud and use them to deliver tasty fresh water after you grab that energy.
Why are you specifying it on such a large scale? How about if you built this ring in your living room, and batted around the balls with flippers there?
It’s the same basic thing - if you’re counting on the balls to have kinetic energy from rolling around this ring, where does that kinetic energy come from?
