By Sarah Vogelsong
July 7, 2021 - Coal as a source of power generation may be headed toward the dust heap of history, but its ashes are destined to be considerably longer-lived — and, some hope, could become a building block of tomorrow’s electricity and many other crucial products.
The byproducts of burning coal for electricity are a widely recognized environmental liability. Millions of tons of coal ash — an umbrella term for ash particles, boiler slag, sludge and other coal plant residues — have been stockpiled around the U.S. in ponds and landfills. Virginia is home to more than 26 disposal sites, of which five are still active.
Dominion Energy's Chesterfield Power Station is one of four sites across the state that is subject to new coal ash pond closure restrictions under compromise legislation that passed the General Assembly and was signed by the governor.
Photo by Ryan M. Kelly
Containing arsenic, mercury and cadmium and other heavy metals that can contaminate water supplies, coal ash was propelled onto the national environmental agenda by high-profile spills at impoundment ponds in Tennessee in 2008 and North Carolina in 2014. The latter spill led to the release of thousands of tons of coal ash and millions of gallons of contaminated water into the Dan River in both Virginia and North Carolina.
Now, researchers and state and federal officials are hoping to tap into the industrial waste stream for some of the key building blocks of a new energy system built on renewables and batteries: rare earth elements and critical minerals such as aluminum, cobalt, lithium and titanium.
“The entire green energy industry is heavily dependent on a range of critical minerals,” said Michael Karmis, director of the Virginia Center for Coal and Energy Research at Virginia Tech.
As nations move to reduce carbon emissions, demand for rare earth minerals is expected to soar. One report by the International Energy Agency found that meeting the Paris Agreement goal of limiting warming to less than 2 degrees Celsius would require “a quadrupling of mineral requirements for clean energy technologies by 2040.” President Joseph Biden’s administration has estimated that global demand for lithium and graphite, both of which are used in batteries, will jump by 4000 percent by the same year.
“The kind of desktop computer we had in the 1980s took about 15 elements from the periodic table,” said David Spears, director of the Virginia Department of Mines, Minerals and Energy’s Division of Geology and Mineral Resources. “Now, especially with smart screens and touchscreens, these devices require something like 75 elements.”
Digital devices aren’t the only big consumers of minerals and rare earths. Electric cars require six times more minerals than cars with internal combustion engines, while an onshore wind facility needs nine times more minerals than a gas plant, according to the IEA.
Most of those resources, however, currently come from China — which not only mined about 60 percent of the world’s rare earths in 2019 but processed almost 90 percent of them.
With the race to decarbonize accelerating, officials are increasingly hunting for domestic sources of these commodities. Research has shown rare earths and critical minerals exist in both coal byproducts and other geological deposits, but figuring out how to extract them on a commercial scale has proven more difficult.
Virginia will serve as one testing ground for a broader deployment of the idea beginning this summer. In April, the U.S. Department of Energy awarded $1.5 million to the Virginia Center for Coal and Energy to lead a team to examine not only extraction but processing of rare earth elements and critical minerals from coal and coal byproducts in the Central Appalachian basin. Participants will include West Virginia University, the University of Kentucky, state and federal agencies including DMME and regional economic development groups, among others. Dominion Energy will also offer assistance, although Appalachian Power will not be involved, spokesperson Teresa Hall said in an email.
“There’s an opportunity to take an environmental liability and turn it into an environmental asset,” said Karmis. “All the major mining companies are pushing this big time.”
What are rare earth elements and critical minerals?
“Rare earths” are something of a misnomer, not actually being rare. The label is given to 17 metallic elements that are highly similar to one another and often found in nature together. These elements are grouped together as one entry on a list of 35 “critical minerals” identified by the U.S. Department of the Interior in 2018 as “vital to the nation’s security and economic prosperity.” Taken together, these elements are all considered critical not only because of their wide variety of economic and military uses but because the U.S. relies heavily on foreign imports to obtain them.
Appalachia may offer special promise: in 2016, researchers from Duke University found that fly ash, a fine-particle type of coal ash, from Appalachian coal had a higher concentration of rare earth elements compared to fly ash from other U.S. coal basins. Consequently, the researchers concluded, “ashes from Appalachian sources should be prioritized” in any effort to recover rare earths.
For Virginia, like other states within the region, there’s an additional incentive to seed mineral exploration: economic development.
As thermal coal — coal used for electricity generation — has waned in popularity, areas like Southwest Virginia whose economies are built on the resource have found themselves on increasingly shaky ground.
The fourth most coal-dependent area in the U.S., Southwest Virginia has seen both coal employment and production drop precipitously. Over the past two decades, tonnage has fallen by over 70 percent, from 33.3 million tons in 2000 to 9.9 million in 2020, while employment has more than halved, from 4,948 to 1,878 workers. Even the discovery of high-quality metallurgical coal reserves prized for steelmaking hasn’t been able to halt the decline.
“I think we all see the writing on the wall that there’s going to be less and less demand for that steam coal,” said Spears. “And I think we’re all, especially here at DMME, looking for ways to diversify economic opportunities for Southwest Virginia, and this is one potential thing.
“Imagine if we found that some of these coal waste piles had significant amounts of critical minerals in them,” he added. “We could go back and re-mine them and clean them up.”
In deliberations about coal ash cleanup, state lawmakers have already shown a preference for reuse. A major 2019 law required at least a quarter of all coal ash in ponds or landfills in the Chesapeake Bay watershed to be recycled.
Construction has so far been the biggest beneficiary of coal ash reuse. The waste can be repurposed to make concrete, cement, wallboard and other materials. This January, Dominion announced it had signed a contract with Louisville, Ky.-based Charah Solutions to use 8.1 million tons of coal ash from Chesterfield Power Station for the production of Portland cement, the most common type of cement used around the world.
Whether ash could be recycled for both construction uses and minerals on a commercial scale remains unclear, said Karmis: “Potentially yes, but it is difficult to say at what cost at this point and what is the best technology.”
Environmental groups, however, have taken a more cautious approach to the possibilities of extraction.
While the reuse of coal ash has become a popular strategy for dealing with the waste, efforts to obtain rare earths and critical minerals from it “should not overlook legitimate concerns about how ash processing could affect neighboring communities and the environment,” said Jamie Brunkow, the James Riverkeeper and a senior advocacy manager of the James River Association who has been closely involved with the coal ash cleanup issue in Virginia.
“Extraction of rare earth elements currently requires processing and use of acids that at commercial scale may generate new and concerning waste streams,” he wrote in an email. “Considering the toxic elements present in coal ash, the research should evaluate both the technology and the risks inherent in its application.”
Chelsea Barnes, legislative director for environmental and consumer protection nonprofit Appalachian Voices, also warned in an email that “putting workers in direct contact with these materials to extract critical minerals and other elements is extraordinarily dangerous.” Many workers involved in the Kingston spill cleanup have died or contracted cancer and other illnesses, she pointed out; more than 200 sued the cleanup contractor.
Coal ash isn’t the only potential source of rare earths and critical minerals. Both can be found in other deposits to varying extents.
DMME’s Division of Geology and Mineral Resources has identified four critical minerals, including rare earth elements, that have a “high potential for economic commercial development” in Virginia, as well as 13 with “moderate potential.” Exploitation of some has already begun: five areas in Henry, Roanoke, Amherst, Nelson, Dinwiddie and Greensville counties have been mined or prospected for rare earth elements.
Another potential target may be beaches. This July, using funding from the U.S. Bureau of Ocean Energy Management, the division will do a desktop study of technologies that can be used to extract minerals from beach sand, either while it’s been dredged or transported.
“The Atlantic Coast beaches, especially near the mouths of rivers, contain a fairly high fraction of these darker minerals that contain rare earth elements,” said Spears.
The first phase of the Virginia Tech-led study is also expected to begin this summer, once contract negotiations with the Department of Energy are complete. Subsequent phases will depend on findings about where and in what quantities critical minerals and rare earths can be found in the Central Appalachian coalfields and whether they can be extracted.
“We’ve always been interested in the materials that are necessary to support our civilization,” said Spears. “And Virginia just happens to be fortunate to have a great variety of industrial minerals.”