Geothermal brines in California’s Salton Sea could be future source of lithium in the US

Geothermal power plants at the Salton Sea like this one, the John Featherstone plant, produce superheated brine, which is full of lithium and other minerals. (Image by Patrick Dobson, courtesy of Berkeley Lab).

A literature review prepared by Berkeley Lab scientists found that geothermal brines in the Salton Sea region of California are expected to be a major source of domestic lithium for the United States in the future, but that significant technical challenges have to be overcome.

One of the main obstacles is that brine is extremely hot when it comes out of the subsurface, and it contains a rich stew of many dissolved minerals in addition to lithium.

“It comes out at over 100 degrees Celsius,” Will Stringfellow, lead author of the paper, said in a media statement. “So, you have to deal with the heat. And it’s very, very saline – about 25% by weight.”

Stringfellow pointed out that there are many materials in the mix that could potentially interfere with the extraction.

“There is a lot of salt, meaning a lot of sodium, a lot of chloride. There’s also a lot of calcium and magnesium, and other things like iron and silicon,” he said.

However, based on the review he conducted with co-author Patrick Dobson, a few ideas seemed feasible.

In their view, the most technologically advanced method of lithium extraction is adsorption using inorganic sorbents, but other promising technologies are also being developed and could be used in the region, one of them being inorganic molecular sieve ion-exchange sorbents, which are being applied for extraction of lithium from brines.

Geothermal brines in California’s Salton Sea could be future source of lithium in the US
Using various extraction techniques, lithium chloride can be extracted from the brine, then processed into other forms for battery production. (Image by Jenny Nuss, courtesy of Berkeley Lab).

The review looked at the published literature and industrial and government reports, as well as lithium extraction technology patents.

“We were commissioned by DOE’s Geothermal Technologies Office to conduct an independent analysis of mineral extraction technology in the context of geothermal energy production,” Stringfellow said.

“There have been previous reviews of individual fundamental processes, but this is, to our knowledge, the first comprehensive review that looked at the more applied-science side of the process.”

According to the researcher, who is an expert on industrial waste treatment and management, the Department of Energy is interested in both geothermal energy and the lithium supply chain.

Besides conducting this review, Stringfellow and his colleagues at Berkeley’s Lithium Resource Research and Innovation Center have been working on projects focusing on how to determine the chemical composition of hot brine in real-time, without needing to cool it down, enabling better process control to maximize the efficiency of lithium extraction.

They are also working on a techno-economic analysis with two companies operating at the Salton Sea – Berkshire Hathaway Energy and Controlled Thermal Resources – to see if lithium extraction technologies can be done in a way that makes it cost-competitive with other forms of lithium production.