Using Gravity to Generate Electricity

Hypothetically:

I'm on the only planet in the universe, and I have at my disposal a very strong material. I construct a really really long pole, so long that when I'm at the end of it the planet's gravity has virtually zero effect on me. At the end of it I build a giant windmill but with only one feather-light arm. The actual wheel part of the windmill is attached to the main construct (which has heavy mass inside for more gravity) in the same manner as a "spinny" chair.

O = Planet (much bigger than the windmill)
Q = Windmill with single arm coming out
. = Rock

O-------------------------------Q.

Aerial View (you know what I mean):

O= center building attached to pole
( ) = loosely attached rotating wheel
---- = now its the arm not the pole
o = rock

o
-----------( O )

I throw a rock really fast at a perfect trajectory (my arm is that good!) so that the windmill catches it in orbit, and the rock is pushing the windmill arm around and around. Inside the windmill, the generators and transformers are pumping out electricity, which is transmitted down the pole.
Now it seems to me that more electricity would be produced than just the simple kinetic energy I put into throwing the rock. The windmill's gravity keeps it going indefinitely (or at least until the orbit decays), and once the inertia of the arm is initially overcome, I dont see that it would slow the rock down. Perhaps I could start the windmill moving before the rock arrived.


Now the point of this useless maybe:
Setting Newton aside, can gravity be used to create free kinetic energy, and then in turn electricity? Or is gravity utilizing some energy of its own?

EDIT: made some additions to the diagrams

[edit on 13-4-2005 by Zaknafein]

Most likely there would be a negative energy balance between the energy needed to propel the object into the mill, which as you realized would have to be very massive to have any real gravity to it.

However since you brought up the idea, a very long tube extending from the surface of the earth to the Moon (it's magical) would make a good generator. Cover it with induction coils and drop some charged rocks down it towards Earth. That would generate electricity at the cost of some rocks.

However since you brought up the idea, a very long tube extending from the surface of the earth to the Moon (it's magical) would make a good generator. Cover it with induction coils and drop some charged rocks down it towards Earth. That would generate electricity at the cost of some rocks.

You mean sort of like this?

www.enviromission.com.au...

Heh, all three of us are talking about something different.

I think (haven't even convinced myself yet :/) that since gravity is a force that results of nothing more than mere existence, that it can create spontaneous kinetic energy. If that first assumption is true, it would mean energy can be created, despite the current law (conservation of energy) opposing such a notion in every physics book.

I want to use gravity.
Apc is referring to tapping into the Earth's own electric field.
Sardion's is powered by sunlight.

And I have to admit, I like all three.

P.S. apc, what do you mean by negative energy? Just that you'd need a really heavy windmill?

[edit on 13-4-2005 by Zaknafein]

Nono meaning the amount of energy used would be greater than the amount of energy produced. Nearly every "free energy" device ever made atleast makes slightly less if not substantially less energy than it uses.
You would lose energy the moment the rocks hit the mill, loose energy forcing the mill to turn, loose energy with the mill pushing its own axle, and more.

The tube I was talking about used the Earths gravity. Gravity would pull the rock from the Moon to the Earth. It would induce a charge in the lining coils as it passed through them. If it werent a magical tube and was able to be constructed (from low earth orbit to a high lunar orbit), it would definitely be on the level of an investment.. a few million coils would produce a fair amount of energy (if it could be efficiently collected), but it would take a while before the energy produced began to outweigh the energy needed to construct, maintain, and operate such a device. It might not at all.

That's interesting. Since using the moon would be rather difficult, couldn't you just do it from the top of a mountain or off a ledge?

The Moon would be WAY cooler!

You might overcome the force of gravity, but you'd have losses due to friction. The friction would stop the windmill from spinning. Plus, there would be friction in the electrical generator, which would have to be attached to the windmill in order to generate electricity.

.
The moon is held by Earth's gravity. It is 1/4 million miles away.

you are talking about sending the electricity over long distances in a wire. Without super conductors normal wires loose some of the current, longer distance = greater loss of energy.

If you talk to an expert in the power transmission field im certain you will find 1/4 million miles plus would make the energy that actually got back to your planet almost zero.

The energy output depends on energy input, usually with some energy lost to heat, friction, etc.

I don't know if you could use entangled quantum states to actually transfer energy or not. If you could you wouldn't even need a wire and the transmission is instantaneous.

If THAT were possible you could send energy from 26 billion lightyears away instantaneously with no loss.
.

Any time you move energy from one location or state to another, you lose some efficency, usually a good bit of it. Even hydro is not free energy. For gravity to get the water high enough to fall somewhere, the sun had to evaporate the water which condenced and collected later at higher altitude. There are no free rides but the sun is actually buying us the hydro ticket. It is what is putting energy into the system by evaportating the water at the bottom of the gravity differential, converting it into a form where less efficency is lost in getting it back to the top of the system into a form we can harness (vapor---> rain ---> rivers).

The question will always be: At what point in the energy chain could you steal some? With gravity, you can only steal it toward the bottom of the gravity well. Gravity has to have some room (ie: distance in elevation from the energy output) to work because the energy is actually being created by movement. That elevation differential has to be overcome later to keep using the system, which takes... yep, energy.

Maybe someone can figure a way to use the centrifical force and the angular momentum of the planets rotation to do some kind of engineering magic tether thing or a magnetic field doohiky, but you then have to transport the energy to where it is to be used, inducing more inefficency into the system.

I still think the sun is the most abundant and accessable energy source we have or are likely to have in the future. We just need more efficent ways harnessing and storing it. The sun also does most of the energy transportation. In most cases it delivers that good clean energy right to you. It's best to collect the energy as close to where you are going to use the energy as possible.

slank thanks for clearin that up for me.
Thats what I meant when I said "(if it could be efficiently collected)"
Yeah wires that long would have like 12123412.3E^34ohms resistance.
Why do you stomp on my hopes and dreams?

.
i only pointed out the problems with long wires, apc.

I pointed out that perhaps there might be someway of using entangled quantum states as a conductor. Then you could get rid of the wire and resistance altogether.

I think electrons have been demonstrated as entanglable.
perhaps some kind of magnetic field alterations using changing quantum states in electrons could be used to drive an electric motor or perhaps even be directly fed as alternating current along a wire where you wanted to deliver the current to.

The transmission distance could be as far as you want to take entangled particles. Even to the far side of the viewable Universe with instant and perfect transmission.

I am completely ignorant about the underlying prinicples of the physics involved.

If it were possible to use it [which i have no real idea about] you could put your windmill any where in the Universe without having to worry about loss of current due to transmission.

The anchor planet wouldn't even have to be the planet you wanted to send the produced energy to.

Your idea sounds like a giant clockwork mechanism using planets and moons.
wild but interesting.

I think about a civilization building a giant shell around its star to help contain and preserve its energy, with only little cut outs to shine on each of its planets. Like spotlight beams.
.