File this one under S for so close, yet so far. Geothermal power plants at the Salton Sea in California produce brine that is extraordinarily high in lithium, which means that the US could vault from a wallflower to a leading producer of the stuff that dreams — well, EV batteries — are made from. The devil is in the details, but the new Hell’s Kitchen geothermal power plant could soon lay all doubts to rest.
Lithium From Geothermal Brine: Good News, Bad News
A new study from the Energy Department’s Lawrence Berkeley National Laboratory outlines the challenges involved in teasing lithium out of geothermal brine.
All the juicy details come under the title, “Technology for the Recovery of Lithium from Geothermal Brines,” in the open-access journal Energies. The press release from Berkeley Lab starts off with the observation that “geothermal brines in the Salton Sea region of California are expected to be a major domestic source of lithium in the future.”
Or, it could all go downhill from there.
“Extraction of lithium from geothermal brines is expected to be particularly challenging,” the lab explains. “The 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.”
To visualize how complex and delicate the extraction process is, imagine you are flipping for baseball cards, except all of your cards are stuck together and they are on fire.
So, Why Bother?
If electric vehicles are to be a truly sustainable solution to the global mobility problem, then supply chain issues need to be addressed, and lithium is one of those supply chain issues.
Pointing fingers at the supply chain for gasmobiles is a cop-out. The idea behind sustainable mobility is to do better, not to repeat the fundamental error of refusing to acknowledge supply chain issues.
The US currently produces barely any lithium, but that doesn’t mean there is barely any lithium here. The problem is how to get at it.
The Energy Department provides a handy rundown of what not to do:
“In South America’s lithium-rich Atacama Desert, lithium exports come from salt deserts, or salares. Salty groundwater is pumped to the surface and evaporates from large surface basins, leaving behind residual salts, including lithium. Though cheap and effective, this process is heavily water consumptive in a part of the world where water is precious. It also has the potential for toxic chemicals to leak into the potable water supply.
“In places like Australia, lithium ore is most frequently mined by open pit: Miners extract the mineral by digging a large pit or quarry. These operations typically generate waste rock and air pollutants and can affect the groundwater chemistry of area aquifers if not handled appropriately.”
Environmental justice is also in play. A new open pit mine planned in Nevada, for example, is already bumping up against damage to a culturally significant region.
A First-Of-Its-Kind Lithium-From-Brine Study
Extracting lithium from geothermal brine is not exactly a mystery. The problem is doing it in a way that makes economic sense, keeping in mind that the mining and evaporation practices frowned upon by the Energy Department are relatively inexpensive.
That’s where the new study comes in. Previous investigations of extraction from brine have focused on individual processes. The new Berkeley Lab study zeroes in on the applied science side, including a review of existing technology patents.
“Extraction of lithium with inorganic molecular sieve ion-exchange sorbents appears to offer the most immediate pathway for the development of economic lithium extraction and recovery from Salton Sea brines,” the research team concludes, listing “solvents, sorption on organic resin and polymer materials, chemical precipitation, and membrane-dependent processes” among the candidates that show promise but are not ready for prime time.
Zeroing In On The Salton Sea
The Energy Department is interested in the brine extraction angle because it hopes to get a twofer: stimulate the nation’s somewhat sleepy geothermal industry while patching a giant hole in the domestic supply of critical materials. Despite some indications that geothermal is poised for growth in the US, though, the Berkeley Lab study indicates the lithium connection may only play out in the Salton Sea.
The study considered geothermal wells in other areas of the US, and zeroed in on the Salton Sea due to the high concentration of lithium in geothermal brine from the region. Of the 1,200 samples studied, more than 900 had a concentration of under 1 ppm. Only 35 had a concentration of more than 20 ppm, and all of those were located in the Salton Sea.
That is a prize ripe for picking.
“Recent academic studies estimated the potential production rate for lithium from the Salton Sea geothermal field to be thousands of metric tons of lithium per year based on the currently installed geothermal power capacity,” the Berkeley Lab team notes.
The team also cites figures from stakeholders in the Salton Sea:
“CalEnergy estimates a potential annual lithium production of 90 thousand tons LCE [lithium carbonate equivalent] from their existing 350 MWe field and estimates that an additional 700 MWe of geothermal power could be developed that could produce an additional 210 thousand tons of LCE per year. EnergySource has plans for a lithium extraction facility at their John Featherstone plant with the objective of eventually producing up to 16 thousand tons of LCE per year. EnergySource estimated that a total of approximately 100 thousand tons of LCE could be produced annually from the Salton Sea region.”
To put it another way, the team cites a study estimating that “proven lithium reserves from the Salton Sea geothermal field are on the order of 2 million metric tons of lithium (or over 10 million metric tons of LCE),” putting it on the level of other “world-class” lithium deposits.
So, What’s Next?
As if on cue, here comes the firm Controlled Thermal Resources with Stage One of its Hell’s Kitchen Lithium and Power project.
Drilling commenced last month on the project, which is billed as “the world’s first, fully integrated, new geothermal-lithium facility to commence construction,” according to CTR.
The CTR plant will add another 50 megawatts in capacity to the 450 megawatts already hosted by the Salton Sea, so it’s a significant uptick in renewable energy production from the area.
CTR expects the plant to go online for power generation in about two years from now, with about 20,000 tonnes of lithium hydroxide to follow soon after, in 2024.
For now, CTR is focused on the power generation aspect.
“We anticipate high brine flow rates and brine temperatures of 550–650 Fahrenheit. Each well is expected to produce clean, firm power for decades,” CTR explains.
The lithium angle will come in after the first two wells are completed and the brine is tested. The system is aiming mainly at producing lithium hydroxide. Potassium, zinc, manganese, iron, and rubidium could also be in the mix.
As for the extraction technology in play, that would be a closed loop, proprietary ion exchange system based on “beads and molecules” developed by the firm Lilac Solutions, which has the backing of Bill Gates’ Breakthrough Energy Ventures along with A-listers Jeff Bezos, Jack Ma, and Michael Bloomberg, among others.
If Hell’s Kitchen pans out, score another win for GM CEO Mary Barra. Under her leadership, GM has left a giant mark on the nation’s renewable energy profile without getting much attention for it, at least not compared to certain other auto companies headed up by non-female execs. As noted last summer by CleanTechnica, GM is also behind the Hell’s Kitchen project and reportedly has first dibs on the goods.
Meanwhile, keep an eye on Lilac. CleanTechnica took note of the startup back in 2018, especially the part where the company’s ion exchange system could be applied to low-concentration brines. We’ll see what happens in the future with the young company.
Follow me on Twitter @TinaMCasey.
Image: Rendering of Hell’s Kitchen geothermal power plant with lithium brine extraction courtesy of CTR.
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