Coal Ash: A Potential Resource Hidden in Waste

Across the United States, millions of tons of coal ash are stored in ponds and landfills. In fact, the country generates around 110 million tons of this byproduct every year. These ash deposits might just hold the key to revitalizing supply chains for crucial minerals.

Last year, researchers from the University of Texas at Austin examined coal ash samples taken from various power plants. They discovered that domestic reserves of coal ash could potentially contain as much as 11 million tons of rare earth elements—essential components for numerous technologies, including batteries, solar panels, and advanced magnets.

This revelation could significantly disrupt the global supply chain for these materials. If the estimates from UT Austin are correct, the available 11 million tons would be nearly eight times the current U.S. reserves of rare earth elements, valued at an approximate $8.4 billion.

As Bridget Scanlon, co-lead author of the study, pointed out, this underscores the idea of finding “treasure in garbage.” The goal is to close the loop, utilizing waste for recovery while simultaneously minimizing environmental impact.

This domestic source of rare earth elements could also help the U.S. reduce its reliance on China, which currently supplies about 38% of the world’s raw rare earth minerals and handles the refining of 85-90% of these materials globally. Furthermore, China provides a significant portion of cobalt, nickel, and lithium needed for electric vehicle batteries, leading to a situation where 75% of EV batteries are manufactured in China.

The heavy reliance on Chinese supply chains poses challenges for U.S. manufacturers, as tariffs can be quite burdensome. Data from the U.S. Geological Survey indicates that nearly all rare earth elements consumed in 2018 were imported, with 80% sourced from China. The Department of Energy has also noted over 50% dependency for certain key minerals.

In recent years, China has intensified its control over rare earth supplies, especially amid rising trade tensions. This only highlights the significant potential of coal ash as a valuable resource for U.S. energy independence in a climate of protective trade measures. While the concentration of rare earth elements in coal ash is generally lower than in mined materials, the abundance of ash and its accessibility make it an attractive option for resource recovery, as noted by University of Texas officials.

However, not all coal ash is equal. The concentration of rare earth elements varies by region, with the Appalachian Basin containing some of the highest levels at 431 milligrams per kilogram. Yet, the rate of recoverability might not be as swift as one would hope—reports suggest that only about 30% of those critical minerals can be easily extracted from this area. In comparison, coal ash from the Powder River Basin has a lower concentration but boasts a higher extractability rate of 70%, making it a more economically feasible choice.

Strengthening the domestic refining industry to recover these vital minerals from coal ash presents both economic and environmental advantages. Salma Pishpati, director of the Critical Mineral Center in Pennsylvania, noted that modernizing existing treatment processes can simultaneously tackle national security needs while addressing long-standing environmental challenges.