Current known lithium reserves are under tremendous pressure due to soaring demand driven by the widespread use of lithium-ion batteries. A recent study by the USGS estimates that there may be approximately 5.1 to 19 million tons of lithium in Southern Arkansas, with the latter representing almost 136% of the United States' current lithium resource estimate.
Delving into the details, this lithium concentration is projected to be in the Smackover Formation brines of Arkansas. The Smackover Formation is a vast and permeable limestone aquifer—a formation of porous limestone rock that can carry water—dating back to the Jurassic geologic era. Importantly, this region is full of mineral-rich brine or salt water. As you may have guessed, these estimates refer not to lithium rocks but to lithium dissolved in brine.
The research team used fresh lithium concentration data in tandem with historical samples to train a machine-learning model that plotted a lithium concentration map, even in areas that didn't have lithium samples. A combination of this model and water testing led the group to the estimate that Arkansas may be housing up to 19 million tons of lithium. Extraction rates of lithium from brine are still a large variable, so the final output will be less than these initial figures; "We have not estimated what is technically recoverable based on newer methods to extract lithium from brines,” said Katherine Knierim, a Hydrologist.
On a more industrial scale, the US relies on foreign countries for roughly 25% of its lithium imports. Researchers estimate that there is enough dissolved lithium in Arkansas to ensure the US no longer needs to depend on imports. In 2022, over 5000 tons of lithium was brought to the surface based on these calculations as a byproduct of the oil, gas, and Bromine industries.
If extraction of even five million tons (lower bound) is possible, this is over nine times what electric vehicles require by 2030. If, hypothetically, 100% of lithium was extracted, the amount of lithium obtained would be over 30 times the global demand in 2030.
Work is currently underway on lithium extraction in this region. ExxonMobil, an energy company, acquired drilling rights in Arkansas in 2023. The company has set ambitious targets to begin extraction by 2027 and power a million electric vehicles by 2030.
The Smackover Formation is emerging as a strategically important location for the US. Otherwise overlooked byproducts of mineral extraction are now proving to be the future's goldmine: lithium.
