Coal country wants back in, and the ash is the ore

Researchers started up a pilot-scale facility in Wyoming in 2025 to scale a federal process for pulling rare earth elements out of coal fly ash — turning a waste stream that power plants have stacked for decades into a feedstock. The process is NETL's Targeted Rare Earth Extraction, or TREE, and it was developed on Powder River Basin ash.

The logic is that combustion does the concentrating for free. Burning Powder River Basin coal leaves fly ash with rare earth concentrations higher than the coal it came from, and the ash is already mined, already ground and already sitting in impoundments and landfills across the country. A project lead at the University of Wyoming's Center for Economic Geology Research described the basin's coal as carrying an abundance of rare earths that the burn concentrates further.

The federal government has been funding the idea broadly: more than $17 million to a round of projects using secondary and unconventional coal-based resources — coal, underclays, tailings, produced water and fly ash — to produce rare earths and critical minerals, plus a rare earth demonstration facility program run out of the Department of Energy.

The size of the prize is contested but large. A 2024 assessment of U.S. coal ash resources estimated 2.62 million metric tons of rare earth elements including yttrium and scandium, with a total extractable value around $165 billion. Pennsylvania researchers have made the case for building pilot projects on the state's legacy ash, arguing that the infrastructure and the waste are both already there.

What nobody has demonstrated is a plant that makes money at scale. Ash varies from boiler to boiler, the extraction chemistry is sensitive to that variation, and the product is a mixed rare earth concentrate that still needs separation — the same bottleneck that constrains every non-Chinese project. The pilot programs exist to answer the cost question, not the geology question.