Toxic Coal Waste Could Help Fuel the Energy Transformation

Rare earth metals are essential ingredients for the energy transformation. As transportation systems electrify and as power grids move to incorporate renewables, they require a steady supply of cobalt, nickel, copper, cadmium, vanadium, and other materials to build batteries and other electronic components.

There is some disagreement among power sector experts about how (and whether) global suppliers of rare earth metals could limit the production of new technologies like EVs. One 2019 study published in Transportation Research estimates global stocks of lithium and manganese could support roughly 12 billion EVs—in an upcoming report, Guidehouse Insights anticipates 127 million EVs on the road by 2030, comfortably below the limit. The abundance or scarcity of rare earth stocks, however, is only part of the puzzle.

The Economics of Rare Earth Metals Is Fragile

China accounts for about 80% amount of the world’s supply of rare earth metals. In May 2019, the country announced production cuts that are expected to substantially increase prices for some minerals through the remainder of the year. Mounting trade tensions with the US are unlikely to improve matters; the Pentagon described China’s degree of control over the rare earths market as a national security risk in a recent report.

Whether relationships between China and the markets it supplies improves or deteriorates, the economics of rare earth metals is fragile. And like any scarce resource, as easy to access deposits are depleted, less accessible deposits become the next option, driving up financial and environmental costs. Is there another option?

Coal Waste Is an Untapped Resource—For Now

Waste management is not a common topic in discussions about the energy transformation. Even in a future where power systems are completely renewable, legacies of fossil fuel extraction are expected to exist for generations to come. Among these legacies are the various forms of toxic coal waste typically stored in settling ponds or lined pits. The US Environmental Protection Agency (EPA) reported that power plants generated more than 110 million tons of coal ash in 2012.

The toxins in coal ash include scandium, neodymium, cobalt, and other rare earth elements. Researchers report that extracting these metals can yield $99 to $534 per ton of ash—unfortunately, the extraction costs for their methodology were significantly higher, between $380 and $1,200.

For now, recovery is not economical, though a key question remains: what happens to the waste products from the recovery process? If volume or toxicity is reduced, then the costs of safely storing any remaining waste might help tip the economic scales. The methodology in the EPA report uses supercritical CO2 to extract the metals, which, if perfected, could eventually become a use for CO2 captured from other projects.

Laboratories around the world are looking for new and improved ways to extract rare earth metals from waste, supported by the US Department of Energy and other parties. Governments and industry must continue to support innovative research that has the potential to drive down the cost of making use of the waste products—because humans are going to have to live with it one way or another.