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Comment by blacksqr | Hacker News Reader

People have been trying for over a hundred years to find ways to extract gold and other precious metals efficiently from seawater, where the supply is virtually unlimited but extremely dilute. When I saw this article my first thought was, maybe this is finally the stuff that could do it.

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NOAA claims there is 1 gram gold / 100 million metric tons of seawater[0]. Even if you could refine it, there has to be other valuable materials at significantly higher concentrations with a plausible profit margin.

[0] https://oceanservice.noaa.gov/facts/gold.html

That's ten grams per cubic kilometer, and given the volume for the Atlantic Ocean I can see in Wikipedia [0], that'd be 3100 Metric Tons of gold, that is around the global yearly production of gold [1]. It's a big number, but yeah, probably there's something else more expensive. Like salt.

At today's price, that's around $650 of gold per cubic km.

A cubic km of Atlantic water, having a salt concentration of 3.3%, would have around 32 million metric tons of salt. At today's cheapest price of 8$ per ton of salt in brine (that I don't even know if it's correct, but i got it from here [2]), that'd be $240 million per cubic km. Way more profitable per cubic km of water (if you don't factor the cost of moving 32 million metric tons of anything :D )

  0: https://en.wikipedia.org/wiki/Atlantic_Ocean
  1: https://en.wikipedia.org/wiki/List_of_countries_by_gold_production
  2: https://www.statista.com/statistics/916733/us-salt-prices-by-type/

And you'd have to move and process that one cubic kilometer of water as well, which sounds easy on paper (just use a pump bro) but that's err. 1.000.000.000.000 liters of water. Heating that up by 1 degree takes 4 kW per liter, or 4 petawatt for the whole lot.

Ridiculous scales, in any case. If I were to think creatively, I'd create a compound or a filter creature that accumulates gold particles naturally and concentrates it. I have no clue what that involves.

I think you could extract Vanadium from seawater by farming sea squirts.

https://en.wikipedia.org/wiki/Vanabin

The Shai-Hulud of the sea.

Desert Power TNG

I did some back of the envelope calculations, there is 1 gram in 100 million metric tons of seawater [0] and there is an estimated 1.3x10^18 metric tons of seawater on earth [1] then the total amount of gold in ocean is about 13,500,000,000 grams of gold

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