ANALYSIS OF COAL ASH RESOURCES FROM POWER PLANTS IN THE GULF COAST REGION FOR POTENTIAL RARE EARTH ELEMENT RESOURCES

There is increasing interest in assessing rare earth element (REE) and critical mineral resources within the United States to enhance future energy security. The objective of this study was to quantify coal ash resources from power plants within the Gulf Coast Basin that could be used to extract REEs. We used reported ash data from the Energy Information Administration (EIA) from 27 active and 12 retired coal power plants between 2008 and 2020 in the Gulf Coast Basin. Results show that ~1.6 billion tons of coal was burned in the Gulf Coast Basin, ~60% subbituminous coal mostly from the Powder River Basin in Wyoming and ~33% lignite from local mines in Texas, Mississippi and Louisiana, with the remaining 5% bituminous coal from many different US States and Columbia (S. America). Average ash contents varied with coal type, ranging from 8% for bituminous, 5% for subbituminous, and 16% for lignite, with the resultant average ash in Gulf Coast power plants of ~0.14 billion tons (2008 – 2020). The byproducts disposition data indicate that the total 180 million tons of ash includes ~70% fly ash and 30% bottom ash. Generation of coal ash was fairly stable at ~15 million tons/yr from 2008 through 2017 but declined to 8 million tons in 2020. About 60% of the ash generated from power plants (~100 million tons) is considered accessible, with most (~80%) disposed in landfills and 12% disposed offsite. Levels of REEs from coal ash from power plants in the Powder River Basin are extremely important for assessing REE resources from ash deposits in the Gulf Coast. Results from the Powder River Basin suggest fairly uniform levels of REEs throughout the Basin, averaging about 380 ppm with middle REEs highest and more extractable because they are Ca-enriched. Integrating data from Gulf Coast ashes with Powder River ash data will be valuable for assessing REE resources from Gulf Coast ash deposits.