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Can Gravity Make Energy?

Shadow

Scholar
S
Joined
Jan 30, 2006
Messages
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Alright lets see this is my first post and I'm gonna make it good, or at least try. Has anyone heard of any known hypothetical ways to extract energy from gravity without resorting to fusion and massive bodies of matter. It should be possible but I haven't heard anything.
 
I can demonstrate it quite well.

First I'll have you stand next to a tall building. I'll go up top with a big rock...

Athough, I suspect you don't mean a translation of gravitational potential energy into kinetic energy.. do you?
 
Appologies, I should have been more clear. I meant to specify using gravity as the main producer of the energy in an extractable way. Kinetic energy applies but the amount of energy used to get the rock that high makes the energy gain null.
 
I know of a mining operation here in northern california that runs rock down a conveyer several hundred vertical feet. They have a turbine (sp?) attached to the conveyer that generates electricity.
 
cbish said:
I know of a mining operation here in northern california that runs rock down a conveyer several hundred vertical feet. They have a turbine (sp?) attached to the conveyer that generates electricity.
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Wouldn't that be nulled by the energy needed to make the hole (in which lies the conveyor) in the first place -- meaning to extract the matter up and out of the hole? Of course I'm assuming the hole was dug out, as it is a mining operation. But even if it wasn't, and the hole was there naturally, the hole will eventually fill up. This would be no different than dropping matter off a mountain -- eventually the mountain would be gone.

But I suspect Shadow is looking for something else -- a way to get energy out of a gavitational field in a manner similar to a black hole. But if I recall correctly, even black holes can evaporate through this process.

BTW, let me be the first to welcome you to the forum.
 
Shadow said:
Appologies, I should have been more clear. I meant to specify using gravity as the main producer of the energy in an extractable way. Kinetic energy applies but the amount of energy used to get the rock that high makes the energy gain null.
Click to expand...

Off hand, I would say no, at least with present or even forseeable technological advancements within the next millennia. To get more energy out than one puts in, it would have to be essentially some form of perpetual motion device.
 
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Geothermal power:

1. Drill really deep dry hole in Earth's crust
2. Put in two ring concentric pipe
3. Pour water into one ring which heads down by gravity.
4. Water gets heated by Earth's internal heat
5. Water comes racing up other ring and powers turbine.

Tidal power:

1. Put turbine in narrow estuary with large tidal range.
2. Incoming tide causes turbine to spin
3. As does the outgoing power.

Power comes from tidal acceleration from Moon and Sun and imperceptably slows down the Earth's rotation. France has one of these on the Cote d'Azur
 
Diamond said:
Geothermal power:

1. Drill really deep dry hole in Earth's crust
2. Put in two ring concentric pipe
3. Pour water into one ring which heads down by gravity.
4. Water gets heated by Earth's internal heat
5. Water comes racing up other ring and powers turbine.
Click to expand...

That's not in the spirit of the original post's question. It's really geothermal, as you titled it, not gravitational.

Tidal power:

1. Put turbine in narrow estuary with large tidal range.
2. Incoming tide causes turbine to spin
3. As does the outgoing power.

Power comes from tidal acceleration from Moon and Sun and imperceptably slows down the Earth's rotation. France has one of these on the Cote d'Azur
Click to expand...

This is more of getting energy out of the motion of the Earth and Moon's inertia (KE) than gravity.
 
Gravity is a conservative field. Any closed path has a net energy change of zero.
 
Good arguments all around, but let me add another hypothetical angle: if we could harness power from gravity, would we be dealing with an infinite energy source? If not, could we run out of gravity? ;)
 
Just thinking said:
Wouldn't that be nulled by the energy needed to make the hole (in which lies the conveyor) in the first place -- meaning to extract the matter up and out of the hole? Of course I'm assuming the hole was dug out, as it is a mining operation. But even if it wasn't, and the hole was there naturally, the hole will eventually fill up. This would be no different than dropping matter off a mountain -- eventually the mountain would be gone.
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Sorry. I didn't explain it well. I was in a hurry. It's an excavation. They're grinding down a mountain, loading rock down a belt to a rail depot and in the process use the rock/belt set up to generate electricity as a side perk.
 
cbish said:
Sorry. I didn't explain it well. I was in a hurry. It's an excavation. They're grinding down a mountain, loading rock down a belt to a rail depot and in the process use the rock/belt set up to generate electricity as a side perk.
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Nice perk. :)
 
Just thinking said:
Nice perk. :)
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I know! A geologist friend of mine saw the belt operation and pitched the idea to me. When we went to pitch it to them, they had already beaten us to it! I'll have to make my millions elsewhere (sigh!).
 
Many a perpetual motion fantasy has been fueled by the notion that gravity has energy free for the taking. What brings the question to mind?
 
hgc said:
Many a perpetual motion fantasy has been fueled by the notion that gravity has energy free for the taking. What brings the question to mind?
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Forget just gravity then, just reduce your coefficient of friction to 0 and gravity will be your best friend! Think outside the box :boxedin:
 
Jimbo07 said:
Forget just gravity then, just reduce your coefficient of friction to 0 and gravity will be your best friend! Think outside the box :boxedin:
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That's nice too, but you still won't get something for nothing -- meaning no free energy. You just won't waste any. Besides, sometimes heat energy as a bi-product is a good thing; for example, the heater in your car.
 
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Just thinking said:
That's nice too, but you still won't get something for nothing -- meaning no free energy. You just won't waste any. Besides, sometimes heat energy as a bi-product is a good thing; for example, the heater in your car.
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So... even though break-even is entirely unphysical it doesn't count as perpetual motion? You have to have energy gain? Stupid rules about initial conditions...

Now we have a tense problem with the word perpetual. When I will have invented my machine it was already energized for all time :eek:

I have to pay more attention to the perpetual motion thread(s)...
 
Jimbo07 said:
So... even though break-even is entirely unphysical it doesn't count as perpetual motion? You have to have energy gain?
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No, you don't need energy gain to have perpetual motion, just no energy loss -- but as you pointed out, that means no friction, which is just as likely as getting free energy. Of course, superconductors may qualify for perpetual motion (of a sort), but it is of no benefit in getting free energy -- which is what really counts.
 
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