Clean tech startup Fluxnium found a way to tap 50,000 years’ worth of nuclear fuel
Fluxnium, a clean-tech startup, says it has developed polymer fibers that can pull dissolved uranium from seawater, tapping an estimated 4 billion metric tons of uranium in the oceans — roughly 50,000 years’ worth at current use rates. The company, which licensed chemistry from U.S. Department of Energy national labs, recently closed a $7 million seed round and says improvements to fiber surface area have driven down extraction costs toward competitiveness with conventional uranium mines.
Why It Matters
If Fluxnium’s approach can be scaled affordably, it could relieve supply pressures tied to rising yellowcake prices and reduce reliance on geopolitically concentrated terrestrial uranium sources, factors that matter as the U.S. plans to expand nuclear capacity. The technique would access a very large, widely distributed resource without conventional mine tailings, altering long-term fuel security for nuclear power.
Key Facts
- ocean uranium estimate: over 4 billion metric tons (about 50,000 years of fuel)
- yellowcake price trend: up 75% in the last five years (per U.S. EIA)
- Fluxnium funding: $7 million seed round led by Congruent Ventures; participants include Active Impact Investments and Constellation Energy
- technology source: chemistry licensed from U.S. Department of Energy national labs
- previous lab cost demonstration: extraction at more than $200 per pound in national lab demonstration
The United States is aiming to substantially scale up nuclear generation by 2050, but higher uranium costs and limited domestic mines threaten those plans. Yellowcake prices have climbed roughly 75% over the past five years, and much of the world’s terrestrial uranium comes from a handful of countries — including Kazakhstan, Uzbekistan, Russia, Namibia, Niger and China — creating supply and geopolitical concerns for buyers in the West.
Fluxnium hopes to tap a far larger, more dispersed source: seawater. The company says the oceans contain in excess of 4 billion metric tons of uranium, an amount it describes as sufficient for roughly 50,000 years of fuel. Fluxnium’s method uses specially engineered polymer fibers, based on chemistry licensed from DOE national labs, to attract uranium dissolved in seawater. The startup reports that boosting the fibers’ surface area has materially increased how much uranium can be captured and driven down costs compared with earlier lab demonstrations.
Operationally, Fluxnium turns the material into long, braided fiber lines that are deployed offshore and hung from buoys in a setup similar to seaweed farming. After remaining at sea for about 30 to 60 days, the lines are hauled back to shore, the uranium is eluted from the material and then purified into yellowcake for sale into existing fuel supply chains. The company says the process leaves no toxic tailings and that individual fiber lines can be reused multiple times; however, manufacturing the fibers and their ocean deployment account for much of the remaining cost.
Fluxnium emerged from stealth with a $7 million seed round led by Congruent Ventures and participation from Active Impact Investments and utility operator Constellation Energy. Founder and CEO Jeff Green, a serial entrepreneur behind Stamps.com, desalination startup NanoH2O and carbon removal firm 1PointFive, told TechCrunch the company’s task is to continue driving cost reductions across the supply chain so seawater extraction can compete with conventional mines. If those cost declines continue, the approach could help address projected structural shortages in uranium should demand rise during the current nuclear renaissance.
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