A research team from the University of Texas at Austin and other institutions is moving from nationwide totals to regional profitability assessments of rare earth resources found in coal ash. Against the $97 billion potential value revealed in a 2024 study, a Gulf Coast study published in March 2026 estimated the value of recoverable material at about $4.40 per ton of ash. Meanwhile, Australia has published trial results showing recovery rates above 90%. While the technology for turning discarded ash into a supply source is advancing, there remains a gap between the enormous total resource value and a genuinely profitable business. What can be extracted from ash, at what cost, and to whom it can be sold—these questions will determine whether the technology becomes commercially viable.
The Element Range That Separates $8.4 Billion from $97 Billion
The basis for the $97 billion figure is a peer-reviewed paper published on September 17, 2024, by Robert C. Reedy, Bridget R. Scanlon, and colleagues. Combining US power plant statistics with element concentration data from existing research, the study estimated the scale of resources recoverable from coal ash. This is not a story about discovering a new deposit—it is a study that recounted waste already sitting above ground as a resource.
The paper's plant-by-plant assessment used shipment and ash-disposal data from 1972 to 2021, covering ash derived from coal mined in the Appalachian, Illinois, and Powder River basins. In calculating value, the researchers assumed that 69% of the ash produced remains available for extraction at its disposal site, then applied region-specific extraction rates. The recoverable amounts were then converted into oxide quantities and valued using 2020 prices.
This calculation actually yields two different dollar figures, depending on which elements are counted.
| Elements assessed | Estimated value (incorporating extraction rates, etc.) |
|---|---|
| Lanthanides | $8.4 billion |
| Lanthanides plus yttrium and scandium | $97 billion |
Rare earths typically refer to a group of 17 elements: the lanthanides plus yttrium and scandium. This paper, however, separates the lanthanide total from the value of the remaining two elements. The commonly cited figure of "roughly $100 billion" is a rounded version of the latter, combined total.
The addition of yttrium and scandium accounts for $88.6 billion—about 91% of the $97 billion total. This can be calculated from the paper's two figures under the same conditions: $97 billion minus $8.4 billion equals $88.6 billion, and $88.6 billion divided by $97 billion gives roughly 91%. In other words, the overall total is not being inflated primarily by the value of elements like neodymium, which draws attention for its use in magnets.
Furthermore, even if a large quantity of a high-value element exists, that does not mean the entire quantity can be sold at the same price. The US Geological Survey (USGS) estimates global consumption of scandium oxide in 2025 at roughly 60 tons, used mainly in aircraft alloys and solid oxide fuel cells. Given the modest size of this market, it is not appropriate to treat a total inventory value calculated at historical unit prices as equivalent to future sales revenue.
The $97 billion figure is neither a profit figure after subtracting recovery costs and capital investment, nor a value reassessed against 2026 market conditions. It is a rough estimate intended to help decide which resources warrant closer investigation.
What Matters More Than Concentration: Can It Be Dissolved and Extracted?
Coal ash contains higher concentrations of rare earths than the original coal, because combustible components are lost during burning while the elements remain in the ash. However, higher concentration does not necessarily mean easier extraction. When elements become locked inside minerals or glassy substances formed during combustion, simply exposing them to a chemical solution is not enough to dissolve them out sufficiently.
In the 2024 paper, ash derived from Appalachian coal had higher element concentrations than ash from the Powder River basin, yet the extraction rates used in the calculations were reversed—30% for the former and 70% for the latter. In eastern ash, glassy substances containing silicon and aluminum make extraction difficult. Powder River ash, which is calcium-rich, is said to be relatively easier to extract from. Evaluating a raw material therefore requires examining both concentration and the physical/chemical form in which the elements exist.
The 2026 Gulf Coast study confirmed this distinction from another angle. The research team compiled analytical data from 118 samples related to lignite and similar materials, but conducted extraction trials on only 5 coal samples and 1 ash sample. Using the same dilute hydrochloric acid, the median extraction rate of rare earths and yttrium from the ash sample was only 3%—far lower than from coal. This is not a result demonstrating the same extraction rate across all 118 ash sites.
This point also matters when transferring the technology to other ash sources within the US. Achieving a high recovery rate with ash from one power plant does not guarantee the same chemical process and workflow will reproduce that result if the coal's origin or combustion conditions differ. A process of actually sampling the ash remaining at each plant and adjusting the treatment method accordingly is required.
The Gulf Coast Study's Figure: About $4.40 Per Ton
A 2026 peer-reviewed paper by Scanlon and colleagues estimated the median value of recoverable material in Gulf Coast ash at approximately $4.40 per ton. This figure uses 2024 rare earth oxide prices, covers only lanthanides and yttrium, and assumes a 30% extraction rate from ash. Note that this 30% figure differs from the conditions used in the dilute hydrochloric acid extraction trial mentioned earlier—it is an assumption adopted specifically for valuation purposes.
Calculating with an estimated ash quantity of about 258 million tons yields a total value of roughly $1.2 billion. However, adding this figure to the national $97 billion estimate would not produce a new nationwide total, since the price baseline year and the range of elements counted differ between the two studies.
The figure of about $4.40 per ton is more immediately relevant to business planning than any grand total. That amount must cover the costs of transporting raw material, processing it with chemicals, and finishing the product. Moreover, the price used in the calculation is for oxides already separated by individual element. Simply extracting a mixture from ash does not mean that price can actually be realized.
On the other hand, breaking down value by element reveals which products are worth developing. In this Gulf Coast study, neodymium and praseodymium (used in magnets), along with terbium and dysprosium, accounted for about 80% of the estimated value of recoverable material from ash. This is a share of value as oxides, not a share of mass. Even under the same banner of "rare earth recovery," increasing total extracted weight and increasing the magnet materials that buyers actually want are two different goals.
The realistic path researchers envision is combining recovery with existing operations. For lignite, elements could be recovered alongside activated carbon production. For ash, resource recovery revenue could potentially offset some costs of pollution control and disposal site remediation. The economics differ substantially between a business that must cover the entire cost of new processing equipment through metal sales alone, and one that incorporates a recovery step into waste treatment that is already required.
What Supports Recovery Rates Above 90%: Chemical Solutions and Trial Scale
On May 14, 2026, Australia's Monash University announced that technology developed by Professor Sankar Bhattacharya and colleagues had achieved recovery rates above 90% in trials, and that a pilot demonstration at a scale of 100 liters per hour was underway. This marks progress in bringing high recovery rates out of the laboratory, but liters per hour is a measure of liquid volume alone. This figure by itself does not establish how many tons of ash can be processed per hour, nor how many tons of product could be sold annually.
A peer-reviewed paper by the same researchers, published online on May 26, 2026, reports extraction conditions using organic carboxylic acids. According to the author-published abstract, the study examined three samples of low-grade lignite fly ash. Under conditions of 1.31 mol/L citric acid concentration, 90°C, a 4-hour reaction time, and an ash-to-liquid ratio of 1g to 50mL, recovery rates of 54–100% were achieved. The paper also states that comparable results were obtained at 250 times this scale. However, the university's announced pilot operation and this paper's trial results should not be treated as results obtained under identical conditions.
The solid-to-liquid ratio deserves as much scrutiny as the recovery rate itself. At a ratio of 1g ash to 50mL liquid, simple conversion implies 50 liters of liquid per kilogram of ash, or 50,000 liters per ton. This is merely a conversion of the trial's mixing ratio—it does not mean that 50,000 liters of fresh water would need to be consumed for every ton processed. How much the chemical solution can be recirculated determines the actual amount of new water and reagents required.
Even so, the process of heating liquid and allowing it to react for a set period requires equipment and energy. Confirming the business case for using citric acid requires measuring not only whether high recovery rates can be maintained, but also whether the solution can be reused repeatedly, and how accumulated impurities would be handled. Between discovering promising extraction conditions and reducing per-unit product costs through continuous operation lies the next set of development challenges.
Boosting Domestic Supply Requires Refining Partners and a Plan for Leftover Ash
In the United States, businesses that separate ore-derived rare earths domestically are already operating. MP Materials reported producing 840 tons of separated neodymium-praseodymium product in the second quarter of 2026. The claim that the US has no domestic refining capacity whatsoever does not match the current situation.
Recovery from coal ash will be evaluated alongside these existing operations with proven production track records. However, existing refining facilities cannot necessarily accept just any ash-derived mixture. Only after confirming the composition and impurities of extracted elements, separating them to the required purity, and securing buyers can this become part of domestic supply. The total quantity of raw material sitting above ground cannot be directly translated into an equivalent volume of import substitution.
The handling of ash itself also requires a clear endpoint. The US Environmental Protection Agency (EPA) states that coal ash contains arsenic, mercury, and cadmium, and that improper management risks contaminating water and other resources. Extracting rare earths does not render the remaining ash harmless. How the resulting solids and wastewater are managed, and whether the leftover residue can be processed to a quality usable in construction materials, will also shape both the costs and environmental benefits of any such business.
What future trials need to confirm is the quantity and purity of product from continuous processing of real ash, the cost after reusing the chemical solution, and viable outlets for sale or disposal of the leftover residue. If these can be combined with existing waste treatment to demonstrate profitability, the ash that has accumulated over decades could become a raw material that helps fund environmental remediation while also expanding domestic material supply.