According to a 2024 study led by geoscientists at the University of Texas at Austin, coal ash from coal-fired power stations in the US contains nearly $100 billion in feasibly extractable rare earth elements. Because Chinese operations generate roughly 70 percent of REEs and handle about 90 percent of the world’s heavy rare earth processing, this neglected waste from fossil fuels provides an essential local source for defense systems and green energy networks.
The Hidden Chemical Wealth in Discarded Coal Ash
Modern technologies, industries, and infrastructure rely on 17 invaluable metals known as rare earth elements (REEs). These elements are used in computers, planes, cars, solar panels, batteries, and wind turbine motors. They are also utilized in defense technologies; for instance, a single F-35 fighter jet contains around 400 kilograms, or 900 pounds, of REEs. Despite their name, these metals aren’t that rare, but they remain expensive and difficult to extract in useful forms.
Geopolitical concentration has created a supply vulnerability. Chinese mines produce around 70 percent of REEs globally, while also accounting for about 90 percent of global heavy rare earth processing, creating a magnet monopoly. The United States has only one major operational REE mine in California, which produces 16 percent of the global rare earth supply, but the nation lacks national processing capabilities. Imports from China currently comprise about 70 percent of the US REE supply.
Fortunately, an untapped alternative is sitting around. Chalky coal ash—a byproduct of burning coal generated after hundreds of millions of years of extreme heat and pressure squeezed long-dead ancient plants—presents a concentrated reservoir. Once the majority of the coal’s combustible substances and overall mass have burned away, the resulting ash exhibits an REE concentration up to 10 times greater than that found in raw, unburned coal. Accessible coal ash holds an estimated 11 million US tons of REEs, nearly eight times the size of total domestic US reserves.
Engineering Solutions for Scalable Extraction
Because of this stockpile, a global race is on to develop practical extraction methods. At Monash University in Australia, engineers are using environmentally benign acids to remove REEs from coal ash. According to Monash researchers, pilot demonstrations have reported 90 percent recovery of all 17 elements.
“The significance of this work lies in its dual impact: reducing environmental waste while securing domestic supply of critical minerals,” explains Monash chemical engineer Sankar Bhattacharya.
The methodology demonstrates versatility. Monash researchers state that if scaled and commercialized, the technique could be used on other common waste streams, including electronic waste and tailings—the material left over after valuable metals have been removed from mined ore.
“We don’t have to dig up new mines. We can use something that’s already processed and just sitting in landfill,” Bennet Thomas, a sustainable resource recovery specialist at Monash University, mentioned in an interview with AAP, noting that greater autonomy over REEs helps mitigate a “national risk”.
Academic backing extends further. Published in the 2025 edition of the Journal of Environmental Management, research by engineers Ruchi Agrawal and Arthur Ragauskas estimated that global coal ash deposits could supply over 300,000 US tons (272,000 metric tons) of REEs annually, pointing out that such a yield could
Overcoming Traditional Processing Barriers
Conventional extraction methods have many drawbacks, including low yields and toxic post-processing waste. Tackling these obstacles, scientists at Northeastern University are actively investigating the issue, using pre-treatment techniques on coal tailings to triple the output of standard extraction procedures.
Transforming these industrial byproducts into a functional supply chain remains an engineering challenge, but the economic and security incentives are significant. As nations prioritize energy independence and a circular materials economy, coal waste represents a domestic bridge away from foreign supply dependencies.
