[warmwaffles]

You still have to deal with the residuals from desalination. About 1/3 of the salt water is useable. The other 2/3s is a brine that can not be used. Not to mention what are you going to do with all of that salt and biological material you just pulled out? You aren't going to be able to sell it.

[close04]

The water distribution on Earth is 97.5% salt water and 2.5% fresh water [0]. Out of those 2.5%, more than 2/3 of the water is trapped in glaciers and ice caps. So overall we have about 0.8% of the Earth's water available for consumption.

So our actual consumption is far below even those 0.8%. But our problem with fresh water isn't necessarily that it's not enough but that it's very unevenly distributed and we tend to be very wasteful.

This being said how much desalination do we have to do until the brine (now 30% more saline than regular salt water) is significantly affecting the overall salinity of the oceans? Desalinating 0.2% of the ocean's water would give humans a 25% more fresh fresh water and the increase in salinity would be marginal.

Does anyone know if an increase that looks as minute as this (0.1% increase is salinity?) is actually a real danger to ocean life and/or currents?

[0] https://en.wikipedia.org/wiki/Water_distribution_on_Earth

[mc32]

I think the problem with brine salinity is that it’s dumped in concentrated areas which might be teeming with sea life. If they evaporated it and dumped huge salt blocks in ocean deserts it could have less impact on marine life.

[close04]

I imagine this isn't a hard problem to solve, there are no major technical limitations to doing something like this and might not even drive the cost up that much.

There are other aspects of desalination that seem far more critical, like the ones related to efficiency and the scale of the required infrastructure.

[mrguyorama]

You'd think it would be profitable to turn that brine into sea salt starter

[LeifCarrotson]

Typically, it's diluted and pumped back into the ocean.

[xeromal]

Diluted with what?

[pjc50]

More ocean.

Some care is involved in doing this so as not to wreck nearby ecosystems, but the ocean as a whole is big enough to absorb a brine flow.