Researchers recently uncovered a treasure trove of rare earth elements — crucial materials for everything from smartphones to wind turbines — in waste left over from burning coal.
A 2024 study led by scientists from the University of Texas at Austin estimated there's $8.4 billion worth of rare earth elements in U.S. coal ash. This diamond-in-the-rough discovery could reduce dependency on foreign sources for the valuable materials, as Interesting Engineering reported in March.
Squeezing additional value from waste can help address another problem: Conventional mining for the critical materials has high monetary, social, and environmental costs. In comparison, the rare earth elements in coal ash have been separated in advance via coal-burning from the ore that normally contains them. This means it can take less energy to refine the materials, per IE.
"There's huge volumes of this stuff all over the country," Davin Bagdonas, one of the study's authors, told the news outlet. "And the upfront process of extracting the [mineral host] is already taken care of for us."
The study estimated that there are 11 million tons of rare earth elements in U.S. coal ash, while it also noted the government estimates 1.4 million tons are held in conventional sources. That would mean there's nearly eight times the nation's known reserves of the critical materials buried in something that's typically considered industrial waste, as IE detailed.
"This really exemplifies the 'trash to treasure' mantra," Bridget Scanlon, co-lead author of the study, said. "We're basically trying to close the cycle and use waste and recover resources in the waste, while at the same time reducing environmental impacts."
Interesting Engineering reported that the study was the first national assessment of coal ash as a rare earth stockpile.
The researchers combed information from federal databases and scientific literature on the locations and qualities of different coal ash resources.
The findings noted that concentrations of rare earth elements varied by region and location and that there is also variation in how easy it is to extract them.
"This kind of broad analysis has never been done. It provides a foundation for further research," Scanlon told IE.
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No way 👎 Although challenges lie ahead in extracting the resources, the rewards could be great. One recent market analysis by Fortune Business Insights projected the global rare earth market will grow from $3.74 billion in 2024 to $8.14 billion by 2032. It said the Asia Pacific region had an 86.14% market share in 2023, but the U.S. market is expected to grow.
Rare earth materials are critical for supporting growth in clean technology, such as electric vehicles and wind energy infrastructure. Such technologies reduce dependence on dirty energy sources — ironically, such as coal-burning — that release air pollution with health impacts and implications for overheating the planet.
Efforts to extract the critical resources from coal ash — along with other programs to recycle them from used technology and mined waste — can reduce the impacts of new mining.
Interesting Engineering described one American company, ElementUSA, that is already looking into the potential for pulling materials from coal ash.
"The idea of getting rare earth elements out of tailings [mining byproducts] just makes sense," said Chris Young, the company's chief strategy officer. "The challenge is turning that common-sense idea into an economic solution."
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