Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Vast Freshwater Reserves Found Beneath the Oceans

sciencedaily.com

Post reply on HN
Print view View original

11–20 of 41 posts

Re: Vast Freshwater Reserves Found Beneath the Oceans

#11

Post by mnw21cam »

mankypro wrote: post #9
leeoniya wrote: post #2

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 :\

From a purely practical point of view, isn't the "community at large" worried about the "rising" sea levels? If we took the fresh water from the aquifers, then refilled them with sea water, presumably that would put a dent in the rising sea levels? I know, I know...just trying to be pragmatic.

http://what-if.xkcd.com/33/ shows just how much the sea level would drop if all ships disappeared. That's probably more volume than you're likely to drink from an aquifer. There's a reason for the saying "a drop in the ocean".

Besides, once we had used that water, it would run back into the sea.

Re: Vast Freshwater Reserves Found Beneath the Oceans

#12

Post by eru »

clord wrote: post #4

We're contemplating going after harder-to-get fossil water because the easy stuff is depleted and can no longer keep up. Sounds like the situation we're in with oil. In the case of water, which replenishes, the 'production cycle' is actually the global fresh-water cycle. If we dirty all of the fresh water faster than the earth can clean it, we're going to have to start drilling for the fossil stuff in hard-to-reach p…

> Who is going to be able to afford to buy all their water like this?

The price of water can never really climb above the price of desalination.

Re: Vast Freshwater Reserves Found Beneath the Oceans

#13

Post by eru »

mnw21cam wrote: post #11
mankypro wrote: post #9

Earlier quoted context omitted.

From a purely practical point of view, isn't the "community at large" worried about the "rising" sea levels? If we took the fresh water from the aquifers, then refilled them with sea water, presumably that would put a dent in the rising sea levels? I know, I know...just trying to be pragmatic.

http://what-if.xkcd.com/33/ shows just how much the sea level would drop if all ships disappeared. That's probably more volume than you're likely to drink from an aquifer. There's a reason for the saying "a drop in the ocean". Besides, once we had used that water, it would run back into the sea.

We wouldn't use the aquifers' water for drinking. (Or at least, drinking doesn't make a dent.) Agriculture and industry are the big users.

Re: Vast Freshwater Reserves Found Beneath the Oceans

#14

Post by sp332 »

leeoniya wrote: post #6
Danieru wrote: post #5

Earlier quoted context omitted.

This might be off-topic but water is in-fact compressible: http://en.wikipedia.org/wiki/Properties_of_water#Compressibi...

not off-topic, maybe just a bit too pedantic. "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...

1.8% of 4 km is 72m, which is very significant when talking about sea level changes.

Re: Vast Freshwater Reserves Found Beneath the Oceans

#15

Post by jbattle »

Danieru wrote: post #5
leeoniya wrote: post #2

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 :\

This might be off-topic but water is in-fact compressible: http://en.wikipedia.org/wiki/Properties_of_water#Compressibi...

Getting further afield, water's density actually changes considerably with a change in temperature. http://en.wikipedia.org/wiki/Properties_of_water#Density_of_...

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").

http://www.lakeaccess.org/ecology/lakeecologyprim4.html

Re: Vast Freshwater Reserves Found Beneath the Oceans

#16

Post by leeoniya »

sp332 wrote: post #14
leeoniya wrote: post #6

Earlier quoted context omitted.

not off-topic, maybe just a bit too pedantic. "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...

1.8% of 4 km is 72m, which is very significant when talking about sea level changes.

it looks like most "deep" platforms listed in the wiki link are ~400m, so this would be 7.2m (assuming the compressibility factor is linear).

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.

Re: Vast Freshwater Reserves Found Beneath the Oceans

#17

Post by ryan_j_naughton »

Regarding criticism that this isn't renewable and delays the move to renewable resources:

At the rate we are damming rivers, we will destroy many river ecosystems. This new potable water source seems less harmful than dams and could be a bridge until the energy costs of desalination are low enough.

If this discovery spurs investment in desalination (since this is simply cheaper desalination due to the lower salinity) that would be an added benefit as it would accelerate the move toward desalination.

Perhaps we could skip the dams entirely (which though seemingly renewable from a water perspective, are highly destructive to river ecosystems).

Re: Vast Freshwater Reserves Found Beneath the Oceans

#19

Post by TrainedMonkey »

Newsflash - vast freshwater resources had been found sitting in form of ice on planetary caps. Those vast supplies of water are expected to last till 2030.

On a serious note, this could be big. Imagine oil like drilling platforms that pump water instead. Now we only need to figure out how economical this is.

Re: Vast Freshwater Reserves Found Beneath the Oceans

#20

Post by kamjam »

mnw21cam wrote: post #11
mankypro wrote: post #9

Earlier quoted context omitted.

From a purely practical point of view, isn't the "community at large" worried about the "rising" sea levels? If we took the fresh water from the aquifers, then refilled them with sea water, presumably that would put a dent in the rising sea levels? I know, I know...just trying to be pragmatic.

http://what-if.xkcd.com/33/ shows just how much the sea level would drop if all ships disappeared. That's probably more volume than you're likely to drink from an aquifer. There's a reason for the saying "a drop in the ocean". Besides, once we had used that water, it would run back into the sea.

Sometime in the last few years, we reached a point where there are, by weight, more ships in the ocean than fish

Nice link. This made me sad :'(

Post reply on HN