The United States needs a domestic source of lithium that can be extracted using renewable energy. Lithium is a key element in the batteries that will enable us to decarbonize the power grid and vehicles.
The superheated brine trapped deep under the earth beneath California’s Salton Sea offers both lithium and renewable energy — and investors are starting to take notice.
Since the 1980s, geothermal plants south of the state’s largest lake have tapped this subsurface source of steamy brine to drive turbines that generate carbon-free power. The brine contains many elements, including metals iron, zinc, manganese — and lithium.
In recent years, researchers and developers have been working on technology to extract this lithium from the brine after it’s used by the region’s geothermal power complex. Proving out a cost-effective way to extract lithium from this brine could create a sustainable U.S.-based source of this key component in lithium-ion batteries and create much-needed employment in a lower-income region, Southern California’s Imperial Valley. It could also improve the economics for geothermal energy projects in the area, which produce clean power around the clock.
“A buildout of this vision could be amazing,” V. John White, executive director of the California-based Center for Energy Efficiency and Renewable Technology, said in a recent phone interview.
Private investors agree — and some are starting to put serious money behind it. One firm working on lithium extraction for a geothermal plant near the Salton Sea, Lilac Solutions, announced in late September that it had raised $150 million from Lowercarbon Capital, Bill Gates’ Breakthrough Energy and others. In July, General Motors, which will need lots of lithium to execute on its multibillion-dollar electric vehicle plans, announced an investment of undisclosed size in Controlled Thermal Resources, the geothermal developer that’s working with Lilac on the project.
Two other companies — Berkshire Hathaway Energy Renewables and EnergySource Minerals — are also working on lithium recovery in the region.
If the technology can be refined and proven effective, lithium extraction from brine could be “game-changing,” the National Renewable Energy Laboratory reported in July, “potentially delivering 10 times the current U.S. lithium demand from California’s Salton Sea known geothermal area alone.”
The potential scope of the region’s lithium supply is staggering. The California Energy Commission estimates that up to 150,000 metric tons of lithium per year would be recoverable from existing geothermal projects at the Salton Sea — enough to meet nearly half the current annual global demand of 300,000 metric tons. A 2020 report from the commission estimated the Salton Sea could produce more than 600,000 tons of lithium per year if more geothermal plants were built there. If that lithium were sold at a price of $12,000 per ton — roughly the midpoint of global lithium prices over the past two years, according to NREL — it would add up to $7.2 billion per year.
But the success of this effort will depend on moving beyond pilot projects to full-scale commercial production.
A “whole other level of complexity”
Much of the lithium now used in lithium-ion batteries is produced by destructive hard-rock mining, predominantly in Australia, and then refined in China. Other major producers of lithium — in Argentina, Bolivia and Chile — extract it from brine that they push to the surface and evaporate in immense pools, a process that uses large amounts of groundwater and has led to soil contamination and other kinds of degradation, according to a 2020 United Nations report.
The lithium-extraction technologies being tested out south of the Salton Sea, in contrast, require just a fraction of the land and water used by other methods, and they are powered by geothermal energy, so they’re less carbon-intensive. The Salton Sea in Southern California is also physically closer to potential major lithium buyers than other sources of the element.
The Salton Sea is an accidental lake created in 1905 when an irrigation channel fed by the Colorado River flooded, and it’s been steadily shrinking ever since. It lies within a former volcanic area where geothermal activity heats briny underground water to an average temperature of 500 degrees Fahrenheit.
This brine contains every mineral in the periodic table, said Elisabeth de Jong, program administrator for the California Energy Commission’s Geothermal Grant and Loan Program. While the amount of lithium in the brine is relatively small, about 200 milligrams per liter, the geothermal plants use so much brine that “it makes sense to recover” lithium from it, she said in a September interview. For example, Berkshire Hathaway Energy Renewables, which operates 10 of the 11 geothermal plants in the area and is working on lithium-extraction pilot projects, processes 50,000 gallons of brine per minute.
But the process of extracting lithium from this mineral brew is highly complex, according to Will Stringfellow, a Lawrence Berkeley National Laboratory environmental engineer and expert in industrial and agricultural wastewaters. Compared to wastewater left behind by oil and gas production, “geothermal brines are a whole other level of complexity,” he said last year. They contain up to 30 percent solids and a stew of dissolved metals and minerals, only a few of which are valuable.
Even so, “we are involved in this because we think it can work,” Stringfellow said in a phone interview last month. “Everyone is waiting with bated breath to see if it works at scale.”
Three competing efforts to extract lithium from brine
There are several different processes that can be used to extract lithium from brine. Those being piloted at the Salton Sea have centered on more modern adsorption technologies made possible by advances in materials science.
Berkshire Hathaway Energy Renewables has two lithium-extraction demonstration projects in the works. Its subsidiary CalEnergy owns and operates 10 geothermal plants along the Salton Sea with 345 MW of capacity, which have been online for at least 35 years.
BHE started building the first of the demonstration projects in April, funded by a $6 million state grant matched with $6 million from the company and expects it to start operating in March 2022. The project will test the technical and commercial feasibility of recovering lithium in the form of lithium chloride from one of its geothermal power plants. It will use an ion-exchange process, which is essentially a molecular sieve that captures only the tiny bits of suspended lithium, Jonathan Weisgall, BHE vice president of government affairs, said in a September interview.
Next year the company plans to start building a second project, funded by a $15 million grant from the U.S. Department of Energy, that will convert the lithium chloride into lithium hydroxide.
Both lithium carbonate and lithium hydroxide are used in lithium-ion batteries, but hydroxide is emerging as the preferred resource because it provides “more bang for the buck,” Weisgall said.
If BHE’s pilot projects pan out, construction of a commercial-scale plant would begin in 2024. Weisgall estimates that 90,000 metric tons of lithium will be recovered per year, a little less than one-third of current annual global demand.
Controlled Thermal Resources plans to commercially extract lithium from brine used in a 50 MW geothermal plant it expects to be online by the end of 2023. It is working on an accompanying extraction unit, which is projected to be operating by 2024, spokesperson Lauren Rose said during a recent phone interview. Controlled Thermal received a $1.5 million grant from the California Energy Commission for this extraction project.
Controlled Thermal is also using an ion-exchange process — this one developed by Lilac Solutions, which is based in Oakland, California. In this process, the brine flows through a tank filled with ceramic beads, and as the “brine percolates through the beads, the beads absorb lithium,” according to Lilac. After the beads are saturated with lithium, hydrochloric acid is used to flush it out, yielding lithium chloride.
This sort of ion-exchange technology seeks to “act like a catcher’s mitt that is perfect for the shape of lithium,” said Peter Fiske, director of the National Alliance for Water Innovation and Water-Energy Resilience Research Institute at Lawrence Berkeley National Laboratory.
Controlled Thermal plans to produce 20,000 metric tons of lithium hydroxide by 2024. As the first investor in the project, GM will have “first rights on lithium produced by the first stage of the…project, including an option for a multiyear relationship,” GM stated.
EnergySource Minerals is planning a project to remove lithium from the brine processed at its 55 MW Featherstone geothermal plant using its proprietary Integrated Lithium Adsorption Desorption technology. The project “just received its permit for construction” and expects to start building in April 2022, company COO Derek Benson said in a recent email.
The company received a $2.5 million California Energy Commission grant and expects its project to produce 20,000 tons of lithium hydroxide per year once it starts operating in 2023. EnergySource says that by the end of this year it will also deploy pilot projects using its proprietary technology outside the U.S.
All of these planned lithium extraction projects will require water, which the Imperial Irrigation District plans to provide as part of its industrial allocation. The geothermal plant owners have not disclosed how much water will be used, but the projects are expected to consume far less than extractive lithium producers in other countries, according to Rizaldo Aldas, a development program official with the California Energy Commission.
After the companies extract the lithium, they will reinject the brine back into the underground reservoir that feeds the steam-driven power plants.
Renewable power, carbon reduction and jobs
Economic lithium extraction from the mineral-laden brine in the Salton Sea region would also provide a side benefit: a revenue stream for the area’s geothermal plants, which have been hampered by their fairly high operating costs.
In late May, the California Public Utilities Commission ordered 1 gigawatt of new geothermal energy as part of its mandate for 11.5 GW of clean power by mid-decade. The Salton Sea area currently hosts about 430 MW of geothermal energy and is projected to be able to support 2 GW. New plants in the area would be more affordable when paired with commercial lithium extraction.
Building new geothermal and lithium-extraction facilities could also provide an economic boost in the Imperial Valley, where low incomes and high unemployment rates have been persistent problems.
California Assemblymember Eduardo Garcia (D), an Imperial Valley lawmaker who has long promoted commercial lithium extraction in his economically disadvantaged district, touted the GM agreement in a July statement: “Our efforts to galvanize a thriving, robust lithium economy in our Salton Sea region is becoming a reality more and more each day.”
Companies receiving California Energy Commission project grants are required to provide economic support and jobs to Imperial Valley communities, the CEC’s Aldas noted. To ensure that happens, a new organization called the Lithium Valley Commission is working with local high schools and colleges to develop a workforce-training curriculum by 2023.
A few thousand local jobs could be created, according to a report by New Energy Nexus. If battery and EV manufacturers build plants nearby, as many stakeholders hope will be the case, the job growth could be far greater.
The Lithium Valley Commission, a product of 2020 legislation to promote lithium extraction from Salton Sea geothermal plants, ultimately aims to create a “clean energy hub.” It will seek to convince manufacturers of battery components, battery cells and electric vehicles to locate facilities in Imperial County, “promoting the sustainable well-being of a county with the highest unemployment rate in the state.”
The endeavor has strong support from state and federal lawmakers. It could receive funding from the budget reconciliation bill now being crafted by Democrats in the U.S. Congress. The Lithium Valley project “couldn’t have more wind in its sails than it has now,” California Energy Commission member Tom Soto said at a meeting last month.
Elizabeth McCarthy is co-founder and managing editor of California Current. She has reported on energy, the climate crisis, water and health issues for various publications and organizations.
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