This text was initially revealed by Hakai Journal.
Seaweed is flexible; it supplies a habitat for marine life, shelters coastlines, and absorbs carbon dioxide. However in the USA, scientists are getting down to see whether or not seaweed has one other notably invaluable trick hidden up its proverbial sleeve: to behave as a salty, slimy supply of valuable minerals.
Inside the U.S. Division of Power is the Superior Analysis Initiatives Company-Power (ARPA-E), a scientific department dedicated to tackling difficult, high-potential initiatives on vitality applied sciences. ARPA-E takes huge swings and appears for giant rewards. And to date, the company has awarded $5 million to 3 ventures investigating whether or not seaweed can function a sensible supply of essential supplies, reminiscent of platinum and rhodium, in addition to rare-earth parts, together with neodymium, lanthanum, yttrium, and dysprosium.
These invaluable parts, which could be captured and concentrated by seaweed, are important to the green-energy transition—and to expertise extra broadly. Seaweed might signify a substitute for standard mining and different prospects, reminiscent of deep-sea mining.
“There are quite a lot of complexities in your complete course of, and that’s why it’s within the class of ‘very exploratory,’” says Schery Umanzor, a seaweed knowledgeable on the College of Alaska at Fairbanks and a lead researcher on one of many initiatives funded by ARPA-E. “The probabilities of success are low. But when we succeed, then the implications are big.”
Two key ideas underlie this analysis, Umanzor says. One, seaweed grows shortly and sucks minerals out of the water to take action. Two, seaweed’s cell partitions are structured from sulfated polysaccharides—compounds fabricated from lengthy chains of sugar molecules. Sulfated polysaccharides are negatively charged, that means they entice positively charged minerals floating close by. “It’s pure chemistry,” Umanzor says. “Optimistic with detrimental, after which it simply collects.”
A number of years in the past, Scott Edmundson, on the U.S. Division of Power’s Pacific Northwest Nationwide Laboratory (PNNL) in Washington State, started digging into whether or not seaweed might retailer invaluable minerals. He’d come throughout a paper describing how rare-earth parts had been accumulating in seaweed in polluted areas alongside Morocco’s Atlantic coast and was struck by the potential.
Studying about seaweed’s pure propensity to sieve minerals from seawater sparked a “wacky thought” to check how far the method might go, Edmundson says. So he and different PNNL scientists ran an experiment to see if they may intentionally develop seaweed to take up minerals. The mission—which was additionally funded by ARPA-E—completed final yr, although they’re persevering with to dig into the subject. To date, the group’s work suggests that seaweed could be processed to supply a carbon-rich part utilized in biofuel manufacturing and a second mineral part containing parts reminiscent of phosphorus.
There are a lot of unknowns, Edmundson says. Totally different seaweeds seem to have distinct mechanisms for getting minerals out of seawater and distinctive methods of incorporating or concentrating them of their tissues. “There’s layers upon layers of variability which are unclear in the mean time,” he provides.
Underpinning all of this analysis are vital, unanswered questions, together with why seaweed absorbs these minerals in any respect, whether or not it will probably achieve this in concentrations excessive sufficient to be helpful, and whether or not the weather could be pulled out in a financially viable means.
The important thing to creating all this work, Umanzor says, is determining find out how to extract metals and rare-earth parts from seaweed with out destroying it. For seaweed mining to make monetary sense, the method wants to depart the algae in good-enough situation to nonetheless be used for different functions, together with as gasoline, meals, or a part in bioplastic manufacturing.
One other essential piece of the puzzle is discovering the best spot to develop the seaweed. Regardless of their identify, rare-earth parts are usually not all that uncommon. These and different essential minerals are current all through the ocean in tiny quantities. But there are areas the place they possible exist in increased concentrations—like downstream from giant deposits on land. That’s why Umanzor and her collaborators are inspecting whether or not rare-earth parts are sloughing off Bokan Mountain, in southeast Alaska, and ending up within the ocean, and whether or not rising seaweed in a close-by bay can snag what runs off. Bokan Mountain is being thought-about for standard mining, but when it really works, seaweed extraction might supply a extra sustainable different.
Susete Pintéus, a marine biologist on the Polytechnic Institute of Leiria in Portugal, co-authored a 2022 overview paper on seaweed’s function within the green-energy transition. She says seaweed extraction alone—if it really works—can’t utterly get rid of standard mining for these metals as a result of the demand is so nice. Seaweeds “can contribute,” she says, “however they won’t remedy the issue themselves.”
Although seaweed assortment can’t absolutely exchange mining, Umanzor says that by extracting supplies as they leach naturally out of the land—as they may on Bokan Mountain—algal mining presents a technique to scoop up minerals that had been going to be misplaced to the ocean.
Umanzor by no means imagined that the common-or-garden seaweed might turn out to be a vessel to seize invaluable supplies. However on this function, it’d help a extra sustainable future.
“Metals have to return from someplace, and extracting them may be very damaging,” she says. “It’s price exploring different prospects that align extra with our concepts of a greener world—or a bluer world.”
