# Startup extracts uranium from seawater to fuel nuclear plants

> Fluxnium's polymer fibers can pull uranium from the ocean, tapping 50,000 years of fuel and dodging geopolitical risks.
- Title: Startup extracts uranium from seawater to fuel nuclear plants
- Summary: Fluxnium's polymer fibers can pull uranium from the ocean, tapping 50,000 years of fuel and dodging geopolitical risks. The ocean contains 4 billion metric…
- Keywords: fluxnium, uranium, nuclear power, seawater extraction, jeff green, congruent ventures, constellation energy, department of energy, clean tech, yellowcake, nuclear fuel, u.s.
- Source: TechCrunch — https://techcrunch.com/2026/09/16/clean-tech-startup-fluxnium-found-a-way-to-tap-50000-years-worth-of-nuclear-fuel
- Author: Tim De Chant
- Published: 2026-09-16T13:00:00+00:00
- Read time: 1 min
- Topics: fluxnium, uranium, nuclear power, seawater extraction, jeff green, congruent ventures, constellation energy, department of energy, clean tech, yellowcake, nuclear fuel, u.s.
## Nuclear fuel prices are soaring
Yellowcake uranium prices jumped 75% in five years. The U.S. wants to triple nuclear capacity by 2050, but fuel costs could derail those plans.
## The ocean holds 50,000 years of uranium
Seawater contains over 4 billion metric tons of uranium, a thousand times more than all identified hard rock mines combined.

> It's like a thousand times more than all identified hard rock mines combined
## Fluxnium cracked seawater extraction
The startup licensed Department of Energy chemistry and improved it to make extraction cost-competitive with traditional uranium mines.
## They raised $7 million seed round
Congruent Ventures led the round with Active Impact Investments and Constellation Energy, which runs the largest U.S. nuclear fleet.
## Polymer fibers attract dissolved uranium
The key breakthrough was increasing fiber surface area. Early lab demos cost over $200 per pound, but Fluxnium brought costs way down.
## It works like seaweed farming
Braided fibers hang off buoys for 30 to 60 days, then get hauled ashore. Uranium is extracted without toxic tailings, and each line is reused.
## Geopolitical risks drive the opportunity
Three-quarters of Western uranium comes from Kazakhstan, Uzbekistan, Russia, Namibia, Niger, and China. Seawater extraction eliminates that dependence.

> If demand comes the way it's being projected, we're structurally short uranium
## Green is a serial clean tech founder
Jeff Green launched Stamps.com in 1996, desalination startup NanoH2O in 2005, and carbon removal company 1PointFive in 2020.
## Key takeaway

The ocean contains 4 billion metric tons of uranium, and Fluxnium has developed a cost-competitive way to extract it using polymer fibers.