hmmm, the ocean's pretty heavy. i wonder what extracting an incompressible fluid from the seafloor's support structure will do to weaken it. will they fill it with saltwater instead?
i guess it shouldnt be much different than oil drilling :\
i guess it shouldnt be much different than oil drilling :\
Push CO2, get back carbonated water? Then it is $1/liter + carbon credits for what doesn't come back up. :)
Besides, once we had used that water, it would run back into the sea.
Nice link. This made me sad :'(
"The low compressibility of water means that even in the deep oceans at 4 km depth, where pressures are 40 MPa, there is only a 1.8% decrease in volume."
also: http://en.wikipedia.org/wiki/Oil_platform#Deepest_oil_platfo...
either way it doesn't matter for this argument. we're talking about the difference between water and whatever it's replaced with such as "nothing" or something cheap and abundant with similar properties.
also, the water we're talking about is not itself 4 km deep. it may be under 4km of sea water, but the fresh water under the seafloor may be only 500m deep with an equivalent pressure of 4 - 4.5 km.
I'm not sure how common this is but I know Lake Michigan goes through an annual cycle where the water alternately mixes and segregates (by temperature). In the summer, the warm, less dense water rises to the top and stays there. In the winter, very cold water is actually lighter than slightly warmer water and a similar stratification happens. In spring and autumn the water temperatures near the surface equalize with water deeper in the lake and much if not all of the lake water circulates ("turns over").
Other posters here are saying, replace it with salt water or CO2. The CO2 idea was answered. As for the "swap seawater for fresh" idea, as soon as you put a significant amount of sea water in there, you no longer have fresh water coming out! The only way to get a freshwater supply from this would be to take all it out before replacing, but then you have the "supporting the ocean bottom" problem in the interim.
Even if not, we can drill and extract fresh water at one end and pump in salt water at the other, until the water we get out becomes too saline. In porous rock the mix rate would be quite low; kind of like pumping salt water into a sponge at one end and extracting the fresh water at the other end (for a while).
This is quite a common practice in the oil industry.
Finally, salt water is more dense than fresh water. If these reservoirs underwater actually are big cavities; we can just pump salt water in the bottom and pump fresh water out the top.
NB: When I say "we can just", I mean, take a wild best guess about where the bottom and top of the well is based on crazy amounts of uncertain data extracted on a well-by-well basis.