It is estimated that the ocean contains 4 billion tons of dissolved Uranium…more than all the viable land-based uranium mines combined. However, the ocean is vast, and the concentration is very low, making extraction expensive…about $560 per pound.
However, technological advances have brought that price down to $300 per pound. This is still 5 times what it costs to mine uranium from the ground, but it is a significant improvement that could prove useful as uranium becomes more scarce in the future.
Everything that is found in the earth’s crust ends up dissolved in the ocean. It is estimated that there are 25 Billion ounces (1.8 million tons) of GOLD dissolved in sea-water…about 11 times the amount of gold humanity has mined over its entire existence. The ocean is the greatest untapped mine of all-time.
However, concentrations are so low that extraction becomes expensive. To compensate for this, instead of mining the ocean for any ONE resource, extract ALL useful minerals…including Lithium, Molybdenum, Tin, Copper, Nickle, Zink, etc…
Advances in nano-filters…especially graphene…and automation could play an important role in making this kind of extraction economically feasible.
Reference: Rapier, Robert (2009) The Gold in the Oceans. Retrieved From: http://www.consumerenergyreport.com/2009/07/26/the-gold-in-the-oceans/
Reference: McNulty, Timothy (1994) Gold From the Sea. Retrieved From: http://goldfever.com/gold_sea.htm
Reference: Bardi, Ugo (2008) Mining the Oceans: Can We Extrct Minerals From Seawater? Retrieved From: http://www.theoildrum.com/node/4558