The United States is aiming to significantly expand its nuclear energy capacity, with a goal of tripling current levels by 2050. However, this plan faces a challenge: the rising cost of uranium, a key fuel for nuclear reactors. According to the U.S. Energy Information Administration, the price of yellowcake — a raw, unrefined form of uranium — has increased by 75% over the past five years. This price hike threatens to complicate the expansion of nuclear power, especially since the U.S. lacks substantial uranium reserves on land. To address this issue, a new startup called Fluxnium is exploring an unconventional source: the ocean. The world's oceans contain an estimated 4 billion metric tons of uranium, enough to supply nuclear power plants for over 50,000 years. Jeff Green, the founder and CEO of Fluxnium, describes the ocean’s uranium reserves as “a thousand times more than all identified hard rock mines combined.” This vast supply could potentially alleviate the current uranium shortage, but extracting it from seawater has proven to be a technological challenge. Fluxnium claims to have developed a method to extract uranium from seawater using specially designed polymer fibers. The technology was originally developed by the U.S. Department of Energy and has been refined by Fluxnium to make it more efficient and cost-effective. The company recently raised $7 million in a seed funding round led by Congruent Ventures, with additional support from Active Impact Investments and Constellation Energy, which operates the largest nuclear fleet in the U.S. This funding comes as the nuclear industry experiences a resurgence, driven in part by the need for reliable power to support AI data centers and other high-energy applications. Green, a seasoned entrepreneur with experience in launching companies in various fields, sees uranium as a significant opportunity. While uranium is not rare as elements go, the supply is concentrated in a few countries, creating geopolitical risks. If demand for uranium grows as projected, the supply could become critically limited. Fluxnium’s technology aims to change this by using polymer fibers to extract uranium from seawater. The fibers are deployed in the ocean, where they absorb uranium over a period of 30 to 60 days. They are then retrieved, and the uranium is extracted and purified into yellowcake, which is sold into the existing supply chain. By improving the efficiency of the process, Fluxnium hopes to reduce costs and make seawater uranium extraction a viable alternative to traditional mining.