As the energy transition pushes the world to decarbonize and slow climate change, demand for rechargeable batteries that power electric vehicles is expected to surge.

Problem is lithium, a key ingredient in batteries, remains in high demand with limited available supply on the market—crippled today by supply chain bottlenecks and environmental concerns regarding extraction as companies work to bring new mines online.

The U.S. is home to only one lithium mine, but some of the country’s most prolific oil- and gas-producing shale plays could play a role in changing that. Blessed by geology, shale reservoirs are also home to the highly sought-after critical energy transition metal, which has shown up amongst others metals in wastewater from hydraulic fracturing, researchers say.

Engineers and scientists have been teaming up in recent years to uncover ways to find and pull lithium from produced water to boost lithium supplies and improve efficiency. Some have tapped nanofiltration technology, while others have designed polymer membranes—to name a few—to help the nascent sector in the U.S.

Kyung Jae Lee, an assistant professor of petroleum engineering at the University of Houston’s Cullen College of Engineering, is adding insight with research in Pennsylvania’s Marcellus Shale play that takes aim at the rock. She’s examining what triggers the release of lithium from kerogen, the source of fossil fuels in shales; how the lithium interacts with reservoir rock as it moves through the system; and identifying variables that could impact production.

Hopes are to lay the groundwork for establishing shale plays as a sustainable and substantial lithium source of lithium, while enhancing modeling and characterization to better target high concentrations of lithium. Combined with other technologies to extract and produce lithium, opportunities to grow supplies could lower costs for devices and equipment that require lithium.

“There is a substantial amount of lithium in the produced water from the shale reservoirs,” Lee told Hart Energy. Crucial to locating high concentrations of lithium in source rock, which has been a challenge to date, is knowing the origin, fate and transport of lithium, according to Lee.

By combining the disciplines of petroleum engineers who study shale reservoirs and geochemists who study lithium, “I am developing transformative characterization tools to figure out where we can find high concentrations of lithium in the shale reservoirs.”

The ongoing work comes as companies across the world aim to scale up production of lithium-ion batteries as supply growth lags demand growth. Driven by demand for EVs, battery lithium demand is forecast to rise tenfold between 2020 and 2030, according to the International Renewable Energy Agency. While lithium is also needed for products such as cell phones and other electronics, IRENA said EV batteries accounted for 34% of lithium demand in 2020. That percentage is expected to jump to 75% in 2030.

It also comes as the Biden administration pushes its clean energy agenda, having invoked in March the Defense Production Act to spur development of critical minerals needed to manufacture batteries for EVs and energy storage.

“Based on the energy transition, it’s very clear that we will need to move to electric vehicles and for the renewable energies like solar and wind we still need energy storage for the batteries,” Lee said. “Lithium will play a very significant role in the energy transition for the clean energy sector.”

Rock brines

Source rock brines occur in subsurface formations deeper than 2 km with highly heterogeneous concentrations of lithium, according to industry research noted by Lee. There also appears to be correlation between total organic carbon and solid lithium concentration in shale plays such as the Green River Shale, Marcellus Shale and other oil fields.

“A significant amount of Li in petroleum source rock is released during kerogen maturation and transported into surrounding sediments,” she said in the paper.

Lee also notes that lithium released from kerogen thermal decomposition can dissolve in brines or accumulate on minerals, but its small size makes it “easily dislodged from minerals through common cations,” example being in the Green River Shale.

“The detection of Li cations in water suggests the abundance of Li in kerogen-rich shale as well as an active exchange of Li between fluid and rock,” Lee said. “Because clay minerals predominantly drive the mineralization and dissolution of Li, fraction of clay minerals will play a significant role in describing the transport of released Li.”

Using a basin-scale numerical simulation model and local sensitivity analysis, Lee evaluated the most influential factors affecting lithium brine. Her research focused on the accumulation of lithium in various spots in source rock systems. She utilized a simplified conceptual model of a petroleum rock system that included components affecting lithium’s release from kerogen, transport through pores and accumulation in the rock system. System properties and conditions included set values for pressure, depth, temperature and effective porosity among others.

Findings showed lithium concentrations in the upper and lower parts of the source rock as well as reservoir rock below the source rock. “Reservoir rock besides the source rock (observation point 4) were 76.2 ppm, 430 ppm, 191 ppm, and 19.1 ppm, respectively,” the paper said. “These values are in accordance with the published values in Li–rich source rock brines and gave us confidence in our developed numerical simulator and the system conditions.”

“Our assumption is the lithium is released from the rock into the water during the organic matter maturation by geologic heat for a long time,” Lee said. “I think it will be very abundant in many different types of rocks like other shale plays or deposits with abundant amount of clay because clay mineral is the host of the lithium.”

Based on prior research that showed positive correlations between solid organic matter content and lithium as a solid, Lee said her assumption is that because shale plays have a lot of immature organic matter there will be more lithium.

“The next step will be the actual application of our chemical and physical phenomena to actually figure out the lithium zones in the shale plays,” Lee said. “Then, we will be working on actual extraction and try to find out the challenges of producing lithium from the actual production water.”

Marcellus and beyond

Focused on the Marcellus Shale, Lee has been working with Pennsylvania-based Eureka Resources, which extracts lithium, calcium chloride, salt, oil and methanol from wastewater produced in the Marcellus Shale. The company announced in 2020 it had received a patent for processes that extracting lithium and other minerals from wastewater.

At the time, the company estimated lithium extracted through its process could supply about 25% of the country’s annual demand from wastewater collected for oil and gas produces in the Marcellus region alone.

“We’ve relied for too long on other countries’ often unreliable supply chains for many products and materials necessary for U.S. security, productivity and economic growth,” Eureka CEO Daniel Ertel said at that time. “Eureka is committed to helping the country improve and strengthen domestic sources of critical minerals by extracting them from oil and gas wastewater.”

Other U.S. universities are also in on the action.

Researchers from The University of Texas at Austin and University of California-Santa Barbara worked together to design membranes that separate lithium from other ions like sodium to improve the lithium extraction process.

A week’s worth of water from fracking in the Texas Eagle could produce enough lithium for 300 EV batteries, or 1.7 million smartphones, UT-Austin said in a news release, citing the researchers.

Pulling lithium from source rock brines could be transformative for the sector, but challenges remain.

“Extracting lithium from source rock brines not only leverages infrastructure and wastewater from existing oil and gas production, it also improves North America’s energy security with a local source of lithium,” said Graham Bain, geoscience product manager for Enverus. “However, the concentration of lithium in these brines is low at 50-150 ppm compared to brines in South America at up to 1,500 ppm.”

Making such projects commercially viable will require substantial amounts of water and high efficiency extraction at large scales, he added.

“Currently, lab scale results such as E3 Metals Direct Lithium Extraction (DLE) technology can achieve 90% lithium recovery but has yet to be proven at large scales,” Bain said. “If the price of lithium continues to explode and large scale, high efficiency extraction technology can be developed, lithium from source rock brines could definitely be a game-changer.”

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