Four billion metric tons of uranium sit dissolved in the world’s oceans right now, roughly 1,000 times the total identified in hard-rock mines worldwide. A US startup called Fluxnium just emerged from stealth with a plan to get at it, backed by $7 million in seed funding and chemistry licensed from the US Department of Energy.
The catch: extracting that uranium currently costs more than twice the market rate, and no one has proven it works at commercial scale.
The timing matters. Yellowcake prices have risen approximately 75% over the past five years, according to US Energy Information Administration data. US policy discussions target tripling nuclear capacity by 2050, yet the country imports the overwhelming majority of its uranium from a short list of geopolitically exposed nations.
Fishing Lines for Uranium
Fluxnium adapts DOE-developed fiber chemistry into an offshore deployment system that resembles seaweed farming more than conventional mining.
Fluxnium’s core technology traces back to Oak Ridge National Laboratory, which developed amidoxime-based polymer fibers capable of selectively attracting uranium ions dissolved in seawater. Fluxnium licenses that chemistry and focuses on fiber manufacturing, surface-area optimization, and deployment configuration to bring extraction costs down.
Braided fiber lines hang from ocean buoys and remain submerged for 30 to 60 days, absorbing uranium as seawater flows past. After retrieval, uranium is chemically eluted from the fibers and purified into yellowcake, the concentrated uranium oxide that feeds the existing nuclear fuel supply chain.
The fibers are reusable and the process produces no toxic mine tailings, which distinguishes it from conventional uranium mining’s large-scale earthmoving and waste management requirements.
“It’s like a thousand times more than all identified hard rock mines combined.” Jeff Green, founder and CEO of Fluxnium, as reported via TechCrunch
The Math That Still Needs to Work
The central challenge is a cost gap that DOE lab demonstrations exposed and that Fluxnium’s $7 million seed round is specifically designed to close.
DOE laboratory demonstrations produced uranium at more than $200 per pound. Western uranium suppliers typically charge well under half that.
Fluxnium’s strategy is to increase fiber surface area and refine every stage of the process to compress that cost, but the company has not disclosed a new target figure and acknowledges that commercial economics remain unproven.
The $7 million seed round was led by Congruent Ventures, with Active Impact Investments and Constellation Energy, one of the largest nuclear plant operators in the US, participating. Green’s background includes commercializing desalination membranes and direct air capture projects. That experience gives investors a basis for evaluating whether he can scale a complex, materials-intensive extraction technology.
“Our job is to drive cost out of the supply chain, keep working through all the stages of the process to make it as low cost as possible.” Jeff Green, via Yahoo Finance/TechCrunch
Who Controls the Fuel Chain
Green has been direct about the geopolitical vulnerability embedded in current uranium supply chains.
Green has stated publicly that two-thirds to three-quarters of Western uranium supply flows from Kazakhstan, Uzbekistan, Russia, Namibia, Niger, and China, countries where political shifts can reshape fuel access overnight.
Demand pressure is building from an unexpected direction. Technology companies and AI data center operators are backing nuclear projects to secure reliable, low-carbon baseload power for compute-heavy workloads. Combined with planned capacity expansion, that demand trajectory could leave the industry structurally short on uranium under projected scenarios.
Fluxnium’s next stated milestone is a verified cost-per-pound figure from an actual open-ocean deployment. No regulatory pathway or marine environmental impact process has been publicly detailed yet. The ocean’s uranium resource is real; the commercial economics are not yet proven. That gap remains the critical distance between 50,000 years of potential fuel and a very expensive science project.
