Resources

Valuable minerals are contained in the ocean in great abundance, but they are dilute and difficult to extract.

Uranium

Seawater contains 3.3 parts per billion of dissolved seawater--though diffuse, this resource is about 4 trillion kilograms or 1000 times more than the uranium reserves in terresterial mines ¹. Recent cost estimates are that uranium from seawater, translated into electricity cost, would cost 1.25 cents/kWh ². Ongoing research, particular into better material for adsorbents, is hoped to bring the cost of seawater uranium recovery to the current spot price of uranium ³,⁴. Seawater uranium extraction has been demonstrated on a small scale ⁵.

To harvest enough uranium for a 1 GW nuclear power plant, it is necessary to process 160 km³ of seawater per year ⁶. It is proposed to attach harvesters to the base structures of offshore wind turbines ⁶. Although the brine produced from desalination plants could offer greater concentrations, no desalination plant is large enough to allow production of uranium at a needed scale ⁶.

Lithium

There are perhaps 200 billion tons of lithium dissolved in the oceans, compared to 21 million tons of known terrestrial reserves and 86 million tons of terrestrial reserves that might be harvested with near-term technology, at a concentration of 180 parts per billion ⁷.

Several recent trials have shown the potential feasibility of harvesting lithium from seawater ⁸,⁹,¹⁰, but the technology remains at the laboratory level. Recovering lithium from more concentrated sources than normal seawater, such as the brine from desalination plants, might be more economical ¹¹.