Harnessing energy from gravity

1. Feb 29, 2004

Erazman

Theres already methods of harnessing energy from gravity (like from the flow of water), but not in very massive amounts. What if we drilled a very deep hole into the ocean (down to the extremely hot farthest reaches of the crust where water will evaporate easily) and set up a generator at the bottom? Have a massive pipe connected from the ocean water to the bottom of the pit. The hole wont fill up with water if ventilate the steam to the air above the ocean (driven by the difference in pressure). Mineral Insulated cables could be run down to the generator. I'm talking extremely hot conditions here to allow the massive amount of water flow to evaporate ASAP.. we would actually be using the earth's heat as a driving force to return the water...

Law of Convservation remains unbroken.. because the steam that rises back up the hole has lost its potential energy from the deep pressures of the ocean and the gravity of the hole... and has given it to us.

There's already a thread on here that talks about harnessing energy from the bottom of the ocean, but not from BENEATH the bottom of the ocean.

2. Mar 1, 2004

Staff: Mentor

Sounds pretty good to me. The main problem is drilling the hole and setting up a generator miles under the ocean floor.

3. Mar 1, 2004

Erazman

okay, now putting aside the problems that come with it (such as disturbing ocean life, the costs of deep ocean floor drilling, etc), can we figure out, theoretically, how much KW/hr we could produce?

Variables:

crust beneath the ocean: 6.5 miles
(lets set it up short of 6 miles) = 30,000 FEET
That should give us plenty of heat to evaporate the water reservoir fast enough so our operation doesnt flood.

Ocean depth of 15,000 feet
(a TREMENDOUS amount of downward pressure)

10 ft diameter pipe (wide open) blasting a large turbine.

Assuming the generator/pipes can withstand this force, and wont overheat.. how much power could we harness?

4. Mar 1, 2004

NateTG

Ultimately, the peak power you can get depends on the flow rate you have.

Since this is a heat engine, you can approximate the peak efficiency at $$1-\frac{T_{min}}{T_{max}}$$
Let's say that the temperature of the lava is 10000 degress Kelvin, and the temperature of the water is about 300 degress kelvin, so the peak efficiency is quite high.

Now, assuming that water has a specific heat of four joules per degree per gram, we can figure that you'll get about 39000 joules of work per gram of water at peak efficiency. That translates to a peak power of roughly 40 gigawatts per ton of water per second.

Since water has a specific density of 1 ton per cubic meter, that's a lot of energy even with a relatively small pipe.

Of course, thermodynamic efficiency is not likely to break 10%, so you're looking at a much smaller amount of power.

On the other hand, the technical challenges associated with actually creating and maintaining that kind of pipeline are very hard.

Geothermal power systems on the Megawatt scale are in use at several locations. You can google for more information.

Effectively, the peak power is equal to the peak heat transportation.

5. Apr 4, 2004

Sariaht

Emmmm. Hmmm!

Let's say we drilled a whole under the north and south pole, and revealed the earth's core; a water stream toroid would form around the hole, since the high speach of gravity drags the water to the pole, and the hot water bursts out of the hole like a geiser. If you managed to tame the energy, you would perhaps gain a bit from doing this! besides, the poles magnetic fields would also become stronger, and its differing position could perhaps be used as an energysource etcetera.

6. Apr 10, 2004

jammieg

There might be an easier way, if the aether theorists are right and gravity propogates through the aether medium like sound through air then an aether vacuum might work better, gravity could supposedly be switched on and off like a light switch, but experimenting with it I haven't tried, somehow magnetism would be needed to pump out the negative and positive aether in a chamber that was designed to make a barrier to both positive and negative aether. If you strongly doubt Tesla's aether theories take a look at tesla lines and ask yourself what a superimposed + and - foam would act like near a magnet?

7. Apr 11, 2004

Nice coder

You do know that aether doesn't exist?

8. Apr 11, 2004

Sariaht

If there were magnetic ether particles you could make a pretty advanced telescope.
I'm sure you could create ether fusion, though the fact that you cannot use ether as a battery, since the particles to small might and perhaps already have lead to other conclusions.

9. Apr 12, 2004

chroot

Staff Emeritus
Sariaht and jammieg,

Please keep your posts about non-mainstream science out of the general forums. They are welcome only in the Theory Development forum.

- Warren

10. Apr 20, 2004

I gues s this is the same sort of thing as geothermal power plants except being at the bottom of a ocean is closeer to the earths core thus more heat, I hav always thought this kind of energy transfer could be profitable compared to say deep drilled oil wells in the ocean, dont really know much about it, btw: for the post about aether look up michleson - morley experiments in google, mind u that was a long time ago.

11. Apr 22, 2004

sheldon

As the steam rose up your pipe vent it would cool and recondense and fall back into the pipe filling it up with water, clogging the system. The water entering the system would cool the lava rock and would stop the system unless you were continually drilling or scraping off the crust.

12. Apr 22, 2004

kronchev

youre going to want something A LOT bigger than 10 foot. As in a 50 foot diameter pump.

13. Apr 22, 2004

kronchev

Itll only cool if it hits something cooler. I suspect the steam would be going very, very fast under all the pressure so in an insulated system (esp surrounded by much much hotter rock) it not only wont have time to cool off, it wont have anywhere to cool off to

the advantage to that is you wont drain the ocean, as soon as it blasts to the surface, itll condense very quickly :p

14. Apr 22, 2004

Atrius

why not simply make a machine above the surface, weighted with magenets so it rotates?

15. Apr 22, 2004

Staff: Mentor

Weighted with magnets? What would that do? Could you elaborate?

16. Apr 25, 2004

MythioS

i think hes thinking a wheel basically.. with like tank track treds all around it. each side of the treds would have an opposing charge. basically the same idea as that little solar glass thingy with the white n black sided diamonds. except instead of dark n light it would be + & -. and instead of solar energy it would be magnetism.

17. May 20, 2004

Simon666

One problem is just as with existing geothermal plants, your hot water cools the underneath hot rock or lava so after a while power output decreases and you would need it to regenerate a couple of years. Drilling holes in the ocean floor is also not exactly the cheapest and easiest thing.

18. Jul 17, 2004

runemerlin

Addressing the problem of cooling steam.

There is no problem. All of the various steam driven power plants in use today utilize a closed system. As the steam leaves the turbine it goes through cooling coils surrounded by water pumped from a nearby river or lake. Once it is cooled it is pumped back into the boiler tubes. This is possible, and doesn't use up all of the energy gained, because, though the pressure is just as high at this end as at the turbine end, the volume to be introduced is much lower than the volume escaping. (This is the reason a jet engine even works.) The steam generated at the bottom of the system can be cooled VERY effieciently by the water at the ocean floor (which is actualy closer to 275 degrees k), and allowed to simply fall back down to the boiler. For best efficiency, however, the generator needs so be as close to the heat source as possible, for obvious reasons.

19. Jul 17, 2004

Kenneth Mann

Can of worms?

Am I missing something here? Assuming that the prodigious engineering feat of drilling, temperature and pressure control,etc. can be handled; let's ignore the action of the water above, and consider that of the magma when it suddenly finds a hole above it. It sounds like instant volcano to me. Why not consider something infinitely simpler (but still not easy), like pressure capping Kilauea (while somehow still allowing the lava to escape) and pumping water up into it's bowl. This will be an incredibly difficult and expensive project, but still a lot easier and cheaper than the sea floor exercise.

20. Jul 17, 2004

shonagon53

May I remind the readers of this post, that in France and Germany, artificial thermal energy pits are already being tested? They're just very deep holes through which water is pumped, which gets heated and then travels back up. One in France (500 metres deep) created half a megawatt continuously. In Germany they're building several of around 2000 metres deep.

So this idea is a bit baked.

You don't need to go offshore for this. Just drill a hole onshore, and divert water into it. That's all you need.

Last edited: Jul 17, 2004