Source: US Geological Survey
Global demand for lithium has skyrocketed as the need grows for batteries to power electric vehicles and store energy generated by wind turbines and solar panels.
USGS estimates show that there is likely enough lithium in the Earth’s crust to meet demand several times over, but accessing it can require large amounts of energy, water and infrastructure. The challenge is getting lithium quickly, efficiently and with minimal environmental impact.
That’s why USGS scientists are looking for it in a surprising place.
From Trash to Treasure?
Each year, billions of gallons of saline water are pumped from deep underground to the surface during oil and gas production. These brines, known as “produced waters”, can be ten times saltier than seawater and can be contaminated with oils, greases and heavy metals that must be pumped back into the ground or intensively treated.
But these waters also contain lithium and other valuable materials.
“Treating waste as a potential resource is a crucial shift for the energy and mineral fields,” said Sarah Ryker, PhD, USGS Associate Director for Energy and Minerals. “Every state, and every country, has legacy waste from extractive industries. A key question is how much of that waste could be put to use to strengthen energy and mineral supply chains.”
Lithium is typically difficult to access. The highest concentrations of lithium are in rocks called pegmatites formed deep under the ground, often at the edge of ancient and vast volcanic systems. Mining these pockets of lithium-rich minerals is expensive, energy and water intensive and can impact local water and air quality.
Instead, much of the lithium produced in the world comes from the briny waters within arid salt flats. Here, lithium-rich fluids are caught in low-lying areas and concentrated over time by high evaporation rates. Producing lithium from brines is typically less expensive and energy intensive than mining hard rock, but still requires considerable infrastructure including a large network of evaporation pools.
Recovering lithium during oil and gas production could provide a new way to meet demands for lithium and other valuable minerals.
To understand how feasible this method might be, however, scientists must know where lithium-rich produced waters might be, and how much lithium they could contain.
Studying the Brines
USGS scientists are working to understand the geologic conditions that create lithium-rich brines and identify locations with potentially high lithium concentrations.
One tool in this hunt is the U.S. Produced Waters Database, a compilation of geochemical information from roughly 113,000 produced water samples analyzed by USGS, academia, private industry, and other federal and state agencies.
Madalyn Blondes, PhD, co-lead of the has worked on the database for over a decade and explains that many of these samples were taken before lithium was in demand, but that the routine lithium measurements are now proving invaluable.
“This database lets us look across the nation to identify national and regional trends in lithium concentration, as well as understand resource availability at the local scale,” Blondes said.
This extensive dataset can also be combined with machine learning algorithms to predict how much lithium is in locations that haven’t been sampled. Katherine Knierim, PhD, USGS research hydrologist has been working on estimating the total lithium that could be recovered from oil and gas production in the Smackover formation in southern Arkansas, a hotspot of petroleum production with promising lithium concentrations.
“We’re at a really exciting time where we have both the computing power and the incoming data to run these models and predict where energy and mineral commodities may occur at significant concentrations,” said Knierim.
Down the hall from Knierim, a more micro approach is in action. Here, scientists in the USGS Brine Research Instrumentation and Experimental (BRInE) Laboratory painstakingly measure the concentrations of lithium and other commodities in samples taken at oil and gas wells. Scientists also heat up fragments of rocks taken from deep underneath the ground to mimic the geologic conditions that leach lithium into underground fluids.
“At the USGS, we have both the technical knowledge of how to analyze the samples and an understanding of the geologic context from our research,” said Blondes.
Researchers are beginning to understand how rock-type, chemistry and pressure interact to create valuable brines.
“I think lithium recovery from energy wastewaters has real potential,” Blondes said, “The data are showing that there are high concentrations of lithium in places across the country where it could be a really important resource. And the infrastructure to produce it is already there.”
This research can also be applied beyond petroleum production: USGS scientists are using the same principles to identify locations where geothermal energy and lithium could be produced side-by-side.
One location is of particular interest: the Salton Sea in California.
In 2021, USGS partnered with the Department of Energy in an initiative known as GeoFlight to send low-flying aircraft across the area to gather magnetic, radiometric and elevation characteristics of rocks above and below the ground.
USGS scientists are currently analyzing these data to understand how heat and fluids are generated and transported through the earth, and what locations could be both geothermal and lithium hotspots.
Science for the Future
Ryker explains this research is not only illuminating a potential avenue to help meet demands for lithium and low-carbon energy: it also demonstrates the power of thinking about any geologic resource as a circular economy, where wastes can feed back into production.
“Our science is identifying ways to turn waste into an opportunity, not only a liability,” said Ryker. “Our goal is to bring this science to bear on both clean-up at legacy waste sites and waste management at present-day sites.” The USGS is also researching the potential of recovering minerals from wastes left behind historic mines, and from modern-day mining.
Several companies have already launched pilot programs to recover lithium and other valuable materials from produced waters. If scaling up recovery of minerals from energy wastes proves to be economically and technologically feasible, produced waters, long seen as streams of waste, may be seen with new eyes as streams of resource.
In which case, USGS science will be more important than ever in deciding how best to use the resources below our feet.
