Mining the Sea: America’s Answer to China’s Critical Minerals Grip

21 July 2o26

China’s grip on the world’s critical minerals has long been a source of quiet unease in Washington. Beijing refines roughly 85 to 95 per cent of the world’s rare earths and dominates cobalt, nickel and lithium processing besides, leaving the United States dangerously exposed should the tap ever be tightened.

Now a team at the Pacific Northwest National Laboratory (PNNL) believes the answer may be sitting, quite literally, on America’s doorstep. Their newly developed co-flow reactor draws high-purity magnesium hydroxide straight from seawater, cycling it alongside sodium hydroxide until the mineral precipitates out where the two liquids meet. The method strips out several of the stages older techniques required, and the team has already filed a patent.

“Just 0.1 percent of seawater contains enough critical minerals like magnesium and lithium, if we can fully extract them, to meet humanity’s needs for the next 50,000 years or more,” says Jessica Cross, a chemical oceanographer at PNNL.

The scaling potential is what makes this genuinely interesting. Paired with an existing facility such as the Carlsbad desalination plant in California, PNNL’s own analysis suggests the reactor could yield some 1.16 million pounds of magnesium hydroxide a day – more than triple US domestic demand from a single site. Nickel extraction, researchers say, may follow. It is not a new idea: America mined magnesium from the sea for fifty years before imports took over in the 1990s. What has changed is the chemistry, and the urgency.

Independent reporting on the project notes that PNNL scientists increasingly view the oceans as one of the largest untapped reserves of the lithium, manganese, cobalt and rare earth elements that clean energy and electronics manufacturing depend upon. None of this displaces China’s refining dominance overnight. But it points to a slower, steadier shift: away from a single-source supply chain and towards one where the sea itself becomes a domestic mine.

For an economy that still imports the bulk of its magnesium hydroxide, that is not a small thing.