Nuclear fusion holds the promise of nearly limitless energy, but achieving this goal requires the world to produce a significant amount of concentrated lithium fuel from the ground up.

“A major challenge is the concentration phase, where specific lithium types are concentrated,” explains Samuel Ward from Woodruff Scientific Ltd, a British firm dedicated to nuclear fusion. “There is currently no scalable solution capable of providing the fuel required for future fusion reactors.”

Lithium is essential for the most prevalent fusion technology being developed, which combines two forms of hydrogen to generate energy. Moreover, the rare lithium-6 isotope, constituting only 7.5% of naturally occurring lithium, is the most effective for sustaining the fusion process. Consequently, many fusion power projects depend on “enriched” lithium, increasing the lithium-6 content to over 50%, and occasionally as high as 90%.

Only one demonstration fusion plant is set to outpace experimental reactors by delivering net electricity to the grid. Ward and his team require between 10 to 100 tons of concentrated lithium to initiate and sustain operations. The emergence of a new demonstration plant is expected to heighten this demand.

The initial such plants are projected to be operational by around 2040, allowing time for the enhancement of lithium supplies. However, the enrichment strategy must accelerate—one report indicates that the current lithium-6 supply is nearly non-existent. The U.S. amassed stockpiles during the Cold War, producing approximately 442 tons of enriched lithium from 1952 to 1963 to support nuclear weapon fabrication. This process utilized toxic mercury, leading to environmental pollution that needed remediation for decades.

At present, low-purity lithium for fusion is transitioning from the scarce amounts of highly enriched lithium required for nuclear armaments, according to EGEMEN KOLEMEN at Princeton Plasma Physics Institute, part of the U.S. Department of Energy.

For early integration of power, researchers are advocating for a modernized, eco-friendly version of the enrichment process—yet it still relies on mercury. Last year, the German government allocated funds for a project aimed at advancing this form of lithium enrichment while improving cost-effectiveness. “We plan to launch the first concentration facility in Karlsruhe by 2028,” says Michael Frank, who is participating in this initiative at Argentum Vivum Solutions, a German consultancy.

“The only viable approach for supplying adequate lithium concentrate [in the] short and medium term relies on mercury-based methods,” asserts Thomas Giegalich from the Karlsruhe Institute of Technology in Germany, also a collaborator on the project. However, this type of method will not suffice for the extensive requirements of hundreds or thousands of commercial fusion reactors.

“There is broad recognition that mercury-dependent processes cannot sustainably support the widespread deployment of fusion energy,” states Adam Stein from the Breakthrough Research Institute, a research center based in California.

Various mercury-free concentration techniques are under exploration, but they are not yet suitable for immediate application. This is also the case with the UK’s Atomic Energy Agency, which is funding the development of a clean lithium enrichment process, including efficient lithium-6 separation through microorganisms.

“Given the current lack of demand and the need for further innovation, other techniques have yet to be demonstrated at a commercial level but must succeed,” says Stein.