Looking to wastewater for alternative energy materials
In the coming decades, the demand for critical materials needed for alternative energy technologies such as solar, wind, nuclear, batteries, and fuel cells is expected to significantly increase. If these materials could be recovered from the wastewater of municipalities, power plants, and other underexplored nontraditional water sources, it could go a long way toward meeting that demand.
To get a better understanding of how abundant these alternative resources might be and which are the most promising, Professor Lea Winter led a team of researchers in examining multiple sources of data. Their results are published in Joule.
Why it matters
The global transition to clean energy technologies depends heavily on the availability of key materials. Current projections indicate that the availability of these materials may not be able to meet the rapidly growing demand by 2040. Further complicating the limited supply is that often these materials are found only in certain parts of the world, potentially causing supply chain problems.
For the most part, these materials are collected from mining and other primary sources, as well as from recycling. Due to potential ecological and health impacts of mining projects on local communities, though, the researchers write in their paper that finding alternative sources is crucial. Examples include the acidic and metal-rich drainage from mines and the brackish groundwater processed in water treatment facilities.
“These are typically viewed as waste and sent back out into the environment, but many of them are actually enriched in a number of critical materials,” said Winter, assistant professor of chemical & environmental engineering.
Co-authors of the study include Max Saffer-Seng, an undergraduate student at Yale at the time, who is now a Ph.D. student at the University of Colorado Boulder. Researchers from Northeastern University also collaborated on the work. The team relied on data from the U.S. Department of Energy, the European Commission, the United States Geological Survey, and other agencies.
Where to find the critical materials
In their survey of the data, the researchers found that magnesium and lithium were the most abundant in the water sources considered. After that, in the medium to high category are uranium, titanium, fluorine, and silicon. As a result, the researchers said, recovery of these materials may be possible using readily available technologies.
It’s easier to recover materials when there are high concentrations of it. One challenge, though, is that sources with high concentrations of one material are likely to also have other materials.
“So we need ways to target not just one material,” Winter said. “Maybe we can extract a few materials together and then further process the stream with finer separations to address a number of critical material needs.”
They also found that rare earth elements, which are commonly used in permanent magnets for such technologies as wind turbines and electric vehicle batteries, were much scarcer in nontraditional water sources. However, expanding the search for the materials to seawater would lead to more rare earth elements.
“Once you include seawater resources, you start to see materials like rare earth elements showing up in more significant amounts,” she said. “You also see an increase in a number of materials across the board.”
The study also looked at which elements were most likely to turn up in specific nontraditional water sources. Municipal wastewater, for instance, has very high concentrations of copper, titanium, and nickel. In groundwater, they found a fairly even distribution of many materials, such as magnesium, lithium, and transition metals like nickel, copper, cobalt, and manganese. On a more granular level, they found a high amount of platinum in dentistry waste streams.
Overall, Winter said she and her colleagues hope that their work will point to high-level directions for approaching the issue.
“A lot of researchers in the community are starting to think about developing these recovery technologies,” she said. “So we want to set priorities both in terms of which materials are the most promising to focus on and also which water streams might be the most valuable.”
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Published Date
Jul 1, 2026
