Clean tech startup Fluxnium found a way to tap 50,000 years’ worth of nuclear fuel

The U.S. has ambitious plans to triple the capacity of its nuclear power plants by 2050, but that goal might hit a roadblock if plant operators can’t buy fuel at reasonable prices.

Prices for yellowcake, a form of unrefined uranium, are up 75% in the last five years, according to the U.S. Energy Information Administration. Further complicating matters, the U.S. doesn’t have significant resources within its borders — unless you consider the ocean.

The ocean has over 4 billion metric tons of uranium in it, enough for 50,000 years or so. “It’s like a thousand times more than all identified hard rock mines combined,” Jeff Green, founder and CEO of the clean tech Fluxnium, told TechCrunch.

Fluxnium thinks it has solved the problem of how to extract uranium from seawater. Using technology developed at U.S. Department of Energy national labs, the company has an approach that could be competitive with existing uranium mines.

The startup has been working in stealth until now to develop the new technology. Fluxnium gave TechCrunch an exclusive look at its technology. The startup recently closed 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.

Fluxnium is emerging as the nuclear industry in the U.S. undergoes a renaissance. Tech companies have backed several nuclear startups as they search for new sources of electricity to power their AI data centers.

Green’s timing is good, but perhaps not surprising. He’s a repeat founder, having helped launch Stamps.com in 1996, desalination startup NanoH2O in 2005, and carbon removal startup 1PointFive in 2020. He has a nose for where the world is going, and he thinks uranium presents a big opportunity.

While uranium isn’t rare, as elements go, uranium mines aren’t plentiful or evenly distributed. “If you’re in the West, two-thirds, three-quarters of the world’s uranium supply comes from Kazakhstan, Uzbekistan, Russia, Namibia, Niger, China. There’s geopolitical risk.” Green said. 

Those concerns have been bubbling under the surface of the nuclear industry for decades. “Now with this new nuclear renaissance?” he said. “If demand comes the way it’s being projected, we’re structurally short uranium.”

But those concerns would evaporate if someone could find a way to economically extract uranium from seawater.

Fluxnium’s technology uses specially made polymer fibers that attract the uranium that’s dissolved in seawater. The company licensed the chemistry from the Department of Energy, and it has continued to work on the production and configuration of the fibers themselves.

The key has been to increase the surface area of the fibers, Green said. When the technology was demonstrated at a national lab, it could extract uranium at more than $200 per pound, which is more than twice the price of Western suppliers today. But by increasing the surface area, Fluxnium has been able to draw more uranium out of the water, bringing costs down.

Much of the costs are wrapped up in manufacturing the fibers and deploying them in the ocean.

Here’s how it works. After the material has been made into long, braided fibers, they’re hauled out to sea and hung off buoys, similar to the way that seaweed is farmed. After 30 to 60 days at sea, they’re brought ashore, and the uranium is extracted without any toxic tailings left behind. Each line can be reused several times over.

Once the uranium is eluted from the fibers, it is purified into yellowcake. “Then we sell that just as any other mine into the supply chain,” Green said. 

“None of the components of this process are anything novel. It’s all been done in different ways,” he said. “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.”

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Tim De Chant is a senior climate reporter at TechCrunch. He has written for a wide range of publications, including Wired magazine, the Chicago Tribune, Ars Technica, The Wire China, and NOVA Next, where he was founding editor.

De Chant is also a lecturer in MIT’s Graduate Program in Science Writing, and he was awarded a Knight Science Journalism Fellowship at MIT in 2018, during which time he studied climate technologies and explored new business models for journalism. He received his PhD in environmental science, policy, and management from the University of California, Berkeley, and his BA degree in environmental studies, English, and biology from St. Olaf College.

You can contact or verify outreach from Tim by emailing tim.dechant@techcrunch.com.