>>60 is largely right,
>>59 . One way to look at the ocean is that its the largest, continuous body of ore on Earth. Sure, processing a cubic kilometer of ocean to extract some grams of uranium seems pointless, until you realize that we're running out of oil, coal is fairly dirty, and sunlight is free. Why not put a modest platform on the ocean, powered by sunlight or an OTEC, and let it churn away collecting uranium?
This site:
http://peakoildebunked.blogspot.com/2006/01/207-uranium-from-seawater-part-1.html
... explores these claims. Assuming a uniform concentration of 3mg U / m
3 in seawater, processing about 300 cubic meters of seawater at 100% recovery would produce 1kg of Uranium. Assuming a conservative 10% recovery process, that's 3000 m
3, or a cubical body of seawater about 14m (47ft) to a side. That sounds workable.