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Fluxnium has emerged from stealth with a recently closed $7 million seed round to develop uranium extraction from seawater, TechCrunch reported on September 16, 2026. Congruent Ventures led the financing, with participation from Active Impact Investments and nuclear power operator Constellation Energy.
A Different Fuel Source
The startup is pursuing a new source of uranium for the existing nuclear fuel supply chain. Its process captures dissolved uranium from seawater and converts it into yellowcake, the unrefined material sold by conventional mines. The company licensed its underlying chemistry from the U.S. Department of Energy and has continued developing how the collecting fibers are manufactured and arranged.
Fibers Do the Collection
Specially made polymer fibers attract uranium in the water. Fluxnium deploys braided lengths from ocean buoys for 30 to 60 days, then brings them ashore to remove the collected uranium. According to the company, the lines can be reused several times, and extraction leaves no toxic tailings behind.
Founder and CEO Jeff Green told TechCrunch that increasing the fibers' surface area allows them to capture more uranium. Manufacturing those fibers and deploying them at sea account for much of the process's cost.
Cost Remains the Test
The national-lab demonstration extracted uranium at more than $200 per pound, over twice the price of Western suppliers cited in the report. Green says Fluxnium's fiber changes have lowered costs, and the company believes its approach could compete with existing mines. The report does not give an updated extraction cost or a commercial production timetable.
Pressure on Nuclear Supply
The potential buyers are nuclear fuel suppliers and plant operators facing higher raw-material prices. TechCrunch cites U.S. Energy Information Administration data showing yellowcake prices rose 75% over five years, alongside U.S. plans to triple nuclear generating capacity by 2050. Green also argues that the geographic concentration of uranium supply creates geopolitical risk. Seawater extraction would offer another supply route, but Fluxnium's economic case depends on the cost reductions it is pursuing.
Source: Clean tech startup Fluxnium found a way to tap 50,000 years worth of nuclear fuel
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