Coal Ash Holds Huge Cache of Rare Earth Elements

December 13, 2025

Coal ash — the chalky remnants of coal that has been burned for fuel — has been piling up across the United States for decades. New research has found that this waste product contains enough rare earth elements to significantly bolster the national supply without any new mining.

Rare earth elements are a group of 17 elements that are essential for modern technology, but the United States relies heavily on imports for its supply, with about 75% coming from China. 

Researchers found that there could be as much as 11 million tons of rare earth elements in accessible coal ash in the United States, which is nearly eight times the amount that the U.S. currently has in domestic reserves, according to the researchers. The research found that about 70% of the coal ash produced from 1985 to 2021 — a total of about 1,873 million tons — is potentially recoverable, with the material stored in landfills, ponds and offsite storage areas. 

The study is the first to tally national coal ash resources. It estimates that $8.4 billion worth of rare earth elements could be extracted from the accessible supply.