| Aaron SEIA - 2/6/2014 12:31
Curious if you know...after they remove the salt and other minerals, where does it go? In 1,000 gallons of water, how much salt is there? How many billions of gallons a year would be needed and what would be done with the "stuff other than water"? I agree, it would seem like the logical thing to do. I can see some environmentalists having problems with it, though. Salt, energy use, etc.
Let's stop mining salt from underground or salt lakes if we want to be serious about desalination.
The first obvious use is in human food and animal feed, as well as for curing and preserving. We probably don't do enough of it, preferring freezing or refrigeration to these cheap preservation techniques. I can't even find brine cured pork in the stores, and most dry cured meats are luxury gourmet food instead of everyday food.
Then road deicing probably comes to mind next this season, but the main use by far is the chemical industry. Salt is sodium chloride, and is currently the main source of chlorine and sodium hydroxide. Interestingly, the electrolysis process used to produce chlorine also produces hydrogen, a clean fuel. So chlorine production is almost as intensive as steel or iron, but we get some of our money (energy) back.
The second main product is magnesium chloride, the "nigari" used to coagulate soy milk into tofu. No worry, it also has many other uses. Then I think most of the slurry is gypsum and potassium, which are fertilizers and soil improvers, and a bunch of other lower concentration minerals, rare earths and metals, which can probably be recovered and put to use somewhere.
And if we don't filter finely enough and pump too much plankton, we can always use it to feed farmed mussels, oysters or fish... ;)
We use about 250 MT of salt, 64 MT of chlorine and 50 MT sodium hydroxide per year.
So to meet the world demand for salt alone, at 3.5% concentration, we'd need to desalinate 7,142 MT of sea water, or 1.9 trillion gallons. Irrigation currently uses about 50 trillion gallons of water for only 61 million acres in the U.S. alone, so I guess if we want fresh water for irrigation too, we'll need to pump back some of that salt into the ocean indeed, or store what we can, or find novel uses for sodium and chlorine.
Going back to California, this state specifically has a lot of sandy desert lands that could host such desalination plants, enough that we can keep some wild desert areas to relocate a couple of geckos...
Edited by Chimel 2/6/2014 18:00
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Pictures from space show CA drought, second article talks about water theft
