Total US salt production is roughly 40 million metric tons (or 40 billion kg) per year.
Let’s say we use this process to desalinate water for just 10% LA County’s water needs. LA County currently uses 1.5mm acre-feet of water per year. In SI units, this is about 2 trillion liters each year.
There’s about 35g of salt in each liter of seawater.
So… at just 10%, we’re desalinating about 200 billion liters a year and producing 7 million tons of salt.
If we desalinate for the rest of the state, or the rest of the Southwest, we’ll easily be producing more salt each year than all of the mining activity nationwide.
At some point the excess salt will have no buyers, and we will still need to deal with it.
I’m a fan of the simpler approach: Build long-ass pipes out into the ocean, and slowly dilute the brine so that it’s not concentrated in any one spot. The total salinity of the entire ocean will not change by any perceptible amount, so long as you don’t drop heavy brine in any one spot.
Sorry, forgot to add sources:
I’m pretty sure we can find more uses for ocean salt. At the amounts we’re talking about people will find uses for it. One of the things people tend to ignore is that ocean water contains a lot more than just salt. It also contains metals and organic compounds. Looking over the Wikipedia article there is a significant component of magnesium, sulpher, calcium, potassium, and bromine. There are even industries devoted to extracting sodium, magnesium, potassium, and calcium from sea water. If we substantially increase the desalination of sea water we could significantly reduce the cost of extracting them. With the amount of brine you’re talking about it would pretty much be free to anyone who could find a use for it, since the alternative is diluting it and pumping it back into the ocean, which is pure cost. At that scale you could likely also extract trace components in significant quantities. The page mentions lithium and uranium were attempted in the past, with uranium never seeing industrial scale due to it being too expensive, but economies of scale and all that.
Those are going to be some long as spipes indeed if you want to pump brine out without salt spots.
