Fluxnium, a Los Angeles startup, has raised $7 million in seed funding to pursue what has long been considered an economically challenging solution to uranium scarcity: pulling the radioactive metal directly from the ocean. Congruent Ventures led the round, with participation from Constellation Technology Ventures and Active Impact Investments, the company announced Saturday.
The funding comes at a peculiar moment for domestic uranium supply. According to Energy Information Administration data, U.S. operators have imported the vast majority of their uranium deliveries in recent years, and just weeks ago New Mexico banned new uranium mining leases on state trust lands starting September 4. Meanwhile, the Department of Energy set targets in November 2024 to triple U.S. nuclear capacity by mid-century, a goal that would require some 200 gigawatts of new capacity.
Fluxnium emerged from stealth on September 16 after filing its Form D with the Securities and Exchange Commission in May. That filing showed $6,999,998 sold to three investors, nearly matching the announced round size.
The company's approach relies on high-surface-area polymer adsorbent fibers deployed on longline aquaculture-style systems, which float in the ocean for 30 to 60 days. The fibers passively capture dissolved uranium. Crews then bring them ashore to elute the metal and purify it to yellowcake, the industry-standard uranium concentrate. After that, the lines go back out.
"None of the components of this process are anything novel," CEO Jeff Green told TechCrunch in September. "It's all been done in different ways. Then we sell that just as any other mine into the supply chain."
Green has a track record in diverse ventures. He co-founded Stamps.com in 1996 and later launched desalination startup NanoH2O, which LG Chem acquired in 2014. More recently, he helped establish carbon-removal platform 1PointFive and serves as executive chairman at nanobubble company Moleaer. His co-founder and executive chairman, Jim McDermott, is managing partner at Rusheen Capital Management.
The Chemistry and the Challenge
The underlying chemistry wasn't invented in-house. Fluxnium licensed the technology from a U.S. Department of Energy national lab, the company said. Its own work centers on fiber manufacturing and configuration, tweaking the design to maximize surface area and drive down costs. Earlier laboratory demonstrations put extraction costs above $200 per pound, according to published reports. Fluxnium says it projects costs eventually competitive with conventional mining, though the company declined to share specific targets or pilot timelines.
The appeal is in the scale. Oceans hold an estimated 4 to 4.5 billion metric tons of dissolved uranium, according to DOE and Pacific Northwest National Laboratory research. That's orders of magnitude larger than identified terrestrial deposits. "It's like a thousand times more than all identified hard rock mines combined," Green said.
But scale alone doesn't guarantee economic viability. Uranium spot prices stood at $81.55 per pound at year-end, according to UxC data cited by Yellow Cake PLC in a January update. Three-year forward prices were at $101 per pound and five-year at $108 as of late July, Reuters reported via TradingView. For seawater extraction to pencil out, costs would need to drop considerably from those early lab figures.
Congruent Ventures, an early-stage climate firm with over $1 billion in assets under management, apparently sees potential. Partner Kevin Kopczynski said in the press release that the investment reflects a belief "there is a new path to making the ocean one of the lowest-cost sources in the world."
Constellation Technology Ventures, the venture arm of the largest U.S. producer of clean energy, joined the round but hedged its language. The firm noted its investment "does not constitute a fuel-purchase commitment at this time," according to the announcement. Jason Murphy, Constellation's vice president of nuclear fuels, described the work more cautiously: "Innovations that could expand domestic sources of uranium are important areas of research for the nuclear energy industry."
Active Impact Investments, a B Corp climate-tech seed investor managing roughly $180 million, rounded out the investor group. General partner Tom Boddez called Fluxnium "the future of uranium supply with clean, lower cost ocean adsorption" in the press release.
Not the Only Bet
Fluxnium isn't alone in chasing seawater uranium. Austin-based SuperCritical Materials announced in late July that it licensed patented PNNL-developed uranium adsorbent technology from Battelle for the same purpose. PNNL operates marine testing infrastructure at its Sequim facility specifically for mineral extraction research.
Historic DOE programs at PNNL and Oak Ridge National Laboratory reported adsorbent capacities of 5.2 to 6.0 grams of uranium per kilogram in 49 to 56 days of natural seawater exposure, according to laboratory publications from 2015 to 2018. Those figures offer a benchmark, though translating lab results to commercial scale has tripped up plenty of startups before.
Fluxnium lists between 2 and 10 employees, according to Dealroom data from September 20. The company said it will use the $7 million for further development, pilot testing and scale-up, but declined to disclose production timelines or where it plans to deploy its systems. Whether the ocean will prove a practical uranium mine or remain a tantalizing idea depends largely on what happens next.
