What happened
Fluxnium revealed out of stealth on Sept 16, 2026 with a $7 million seed round led by Congruent Ventures, with participation from Active Impact Investments and Constellation Energy.
Clean-tech startup Fluxnium emerged from stealth on September 16, 2026, announcing a $7 million seed round led by Congruent Ventures, with participation from Active Impact Investments and Constellation Energy.
According to founder Jeff Green, the world's oceans hold over 4 billion metric tons of dissolved uranium — roughly a thousand times more than all identified hard-rock uranium mines combined, enough for about 50,000 years of nuclear fuel at current demand.
Fluxnium's technology uses specially engineered polymer fibers with amidoxime-like chemistry that attract dissolved uranium in seawater. The company licensed the chemistry from U.S. Department of Energy national labs and has focused on improving fiber production and configuration, specifically increasing surface area.
The deployment cycle is straightforward: braided fibers are hung on offshore buoys for 30 to 60 days, then brought ashore and the uranium is eluted off them, purified into yellowcake — no toxic tailings are left behind, and each fiber line can be reused several times.
Yellowcake prices have risen 75% in the last five years per the U.S. Energy Information Administration; and two-thirds to three-quarters of the world's uranium supply comes from Kazakhstan, Uzbekistan, Russia, Namibia, Niger and China, creating geopolitical supply risk.
Fluxnium claims its early national-lab demonstration extracted uranium at more than $200 per pound — more than twice the price of Western suppliers today. The company says its surface-area improvements have since driven costs down.
How the Technology Works
Fluxnium's polymer fibers contain amidoxime groups that selectively bind dissolved uranium in seawater. The fibers are braided into lines and hung on offshore buoys for 30-60 days. After deployment, fibers are brought ashore where uranium is eluted off and purified into yellowcake. No toxic tailings are generated and each fiber line can be reused several times.
- Polymer fibers with amidoxime chemistry
- 30-60 day offshore deployment
- No toxic tailings, reusable lines
Why it matters for me
Could reshape the global nuclear fuel supply chain and reduce geopolitical dependence on a handful of uranium-exporting nations.
Money
Business Executives · General Public
Seawater uranium extraction could unlock a virtually inexhaustible nuclear fuel supply, reshaping the global energy market.
Money · Safety
Business Executives · General Public
Reducing dependence on Kazakhstan, Russia, and China for uranium could ease geopolitical supply risks.
What to remember
The ocean holds enough dissolved uranium for 50,000 years of nuclear fuel, and Fluxnium's fiber-based extraction could unlock it economically.
Fluxnium claims its seawater uranium extraction tech can fuel civilization for 50,000 years.
Verified sources (3)
Clean tech startup Fluxnium found a way to tap 50,000 years' worth of nuclear fuel
↗Jeff Green raises $7M for Fluxnium's seawater uranium bet
↗Mining Uranium from Seawater
↗Claims and linked sources
4 claimsFluxnium emerged from stealth on Sept 16 2026 after closing a $7 million seed round led by Congruent Ventures with participation from Active Impact Investments and Constellation Energy, which operates the largest nuclear fleet in the U.S.
The ocean holds over 4 billion metric tons of dissolved uranium — Fluxnium's Jeff Green calls it roughly a thousand times more than all identified hard rock mines combined, and enough for about 50,000 years of nuclear fuel.
Fluxnium uses specially made polymer fibers with amidoxime-like chemistry that attract dissolved uranium in seawater. The company licensed the chemistry from U.S. Department of Energy national labs and has focused on improving fiber production and configuration, specifically increasing surface area.
Yellowcake (unrefined uranium) prices are up 75% in the last five years per the U.S. Energy Information Administration; and two-thirds to three-quarters of the world's uranium supply comes from Kazakhstan, Uzbekistan, Russia, Namibia, Niger and China, creating geopolitical supply risk.
Community signals
Signal-only · not reporting“It's like a thousand times more than all identified hard rock mines combined.”