[bruce511]

As a corollary to that, a lot of deserts terminate in coastline. Generating desalinated water from solar in these areas has the side benefit of "creating useful land".

What's left to figure out is the ratio of panels to water to land, and in turn whether the long term value of the land is worth the investment. (Dubai would argue it is.)

[abdullahkhalids]

This will destroy the near shore ecosystem, because desalination dumps brine that kills everything, while at the same time destroying the desert ecosystem because it gets converted into something local flora and fauna can no longer live in.

[bruce511]

I don't think we need worry too much about desert habitats being removed. Deserts are large (and getting larger) and the amount of land which could realistically benefit from desalination is a tiny fraction of that.

While brine can impact local salinity, so does treated-effluent outflows (mixed together they are neutral.) Regardless elevated brine levels drop off sharply from the point of outflow.

[ehnto]

We are really good at mis-estimating scale. So we know brine decreases sharply from the point of outflow, but do we know what 50 years of brine outflow at tens of thousands of locations around the world would do?

If it's profitable, it'll be implemented all over, and underestimating that cumulative effect is something we would plead willful ignorance on as we have done with other industries in the past.

Second point I will try to make, habitats are often unique and small, we would just want to make sure an ecosystem is truly ubiquitous before destroying a small pocket of ecosystem.

Especially now, there are animals that live in just one or few specific spots. We should be careful.

[tzs]

I'd expect that long term the brine would do bad things near the places it is released but would not have any noticeable long term consequences much farther away as long as we don't discharge it somewhere where it destroys something local that turns out to be a dependency of something far away.

That's because almost all the water that is taken out of the ocean will make its way back to the ocean. We just borrow it for a while.

If all the water used by humans were taken from the ocean, we'd take about 1/300000th of the ocean's water per year. Most of that will be back in the ocean within 200 years. That puts the cap on the amount of water that would be missing from the ocean of 1/1500th of its volume, which means that the steady state increase in salt concentration would be less than 0.1%, which is much less than the natural variation in ocean salt levels.

[jdjdjsgwiwj]

With all the talk of rising oceans... Taking some sea water out might be a good thing ;)

[nullc]

The brine levels can be greatly reduced by pumping more water to dilute the brine. RO desal projects tend to optimize for an energy efficient local optima that targets minimum energy subject to maintenance constraints. But if energy is nearly free you can instead pump a lot of extra water to solve the issue by moving more volume over more area further from shore.

[sliken]

Well keep in mind:

  1) cheaper energy means you can mix more water in to get whatever salt level you want.

  2) you can mix in the output of your sewage plants

  3) most water is borrowed and returned, not a huge net loss.  Every toilet full returns to the ocean, every washing machine run, etc.

Solar powered desalination doesn't make the list for things to worry about over the next 100 years.

[fasa99]

>This will destroy the near shore ecosystem, because desalination dumps brine that kills everything,

WRONG WRONG!!!

No, we used the brines to create even more batries which store our solar charge Now we have POWER at day and at NIGHT. 24/7. 247 we are producing the brines, but then that goes onto make more batries. Ain't no ecosystem destroyed here (though I'm sure people will try to perform a regression of muh bad event unto muh new technology because that is a timelessly vogue thing to do)

[burnished]

How in sweet salty fuck is brine being used as a battery?

[zelo]

Like this https://en.m.wikipedia.org/wiki/Molten-salt_battery

Btw touristic heaters are based on https://en.m.wikipedia.org/wiki/Sodium_acetate and that's also energy storage

[woleium]

useful land at the expense of dumping brine in the ocean, which would have unforeseen consequences at scale, i am sure.

[bruce511]

I think there might be local effects from elevated brine levels, but overall nothing substantial.

Compared to the amount of water that is naturally desalinated every day (ie via evaporation), even large scale desalination is a drop in the bucket.

Desalination is already operating on a massive scale in the middle east, and we're not seeing any medium scale effects there. Elevated salinity dissipates very quickly from the point of outflow.

[containedgravel]

>Elevated salinity dissipates very quickly from the point of outflow.

I've not seen any evidence supporting this is the case, but the opposite; large swathes of high-saline concentrated blobs sweeping accross the sealife, killing it. We've had to build specialized very long outflow pipes to give the brine even a change to level

[woleium]

Its also denser, so will settle in basins underwater (search for helocline)

[burnished]

If convenient could you link to such?

[raffraffraff]

Could that not also be stored, or have some use?

[thenthenthen]

Molten salt reactor?

[pshirshov]

Sodium batteries?