This article was originally featured on Hakai Magazine, an online publication about science and society in coastal ecosystems. Read more stories like this at hakaimagazine.com.
Seaweed is versatile; it provides habitat for marine life, shelters coastlines, and absorbs carbon dioxide. But in the United States, scientists are setting out to see whether seaweed has another particularly valuable trick hidden up its proverbial sleeve: to act as a salty, slimy source of precious minerals.
Within the US Department of Energy is the Advanced Research Projects Agency-Energy (ARPA-E), a scientific branch devoted to tackling challenging, high-risk projects on energy technologies. ARPA-E takes big swings and looks for big rewards. And so far, the agency has awarded US $5-million to three ventures investigating whether seaweed can serve as a practical source of critical materials, such as platinum and rhodium, as well as rare earth elements, including neodymium, lanthanum, yttrium, and dysprosium.
These valuable elements, which can be captured and concentrated by seaweed, are essential to the green energy transition—and to technology more broadly. Seaweed could represent an alternative to conventional mining and other prospects, such as deep-sea mining.
“There are a lot of complexities in the entire process, and that’s why it’s in the category of ‘very exploratory,’” says Schery Umanzor, a seaweed expert at the University of Alaska Fairbanks and a lead researcher on one of the projects funded by ARPA-E. “The chances of success are low. But if we succeed, then the implications are huge.”
Two key principles underlie this research, Umanzor says. For one, seaweed grows quickly and sucks minerals out of the water to do so. For two, seaweed’s cell walls are structured from sulfated polysaccharides—compounds made of long chains of sugar molecules. Sulfated polysaccharides are negatively charged, meaning they attract positively…
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