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Demand for lithium is expected to grow exponentially as electronic devices proliferate, energy storage demands rise, and combustion engines are replaced by electric counterparts. The U.S. government has designated the mineral as critical to national security and the economy – and yet currently, lithium comes from foreign regions that in many cases are politically unstable or pose other challenges for the United States.
But a domestic supply may be on the horizon. Several energy companies are focusing on the vast underground geothermal reservoir at California’s Salton Sea as a source of lithium. The recovery process would be added to new or existing geothermal plants, which produce a continuous and controlled stream of clean power.
“Mineral extraction will make for a much better profit picture for geothermal,” says Jim Turner of Controlled Thermal Resources, whose proposed new string of geothermal power plants will be the first purpose-built to also produce lithium.
Berkshire Hathaway Energy, which operates 10 geothermal plants at the Salton Sea, also is hoping to build a demonstration lithium reclamation plant. Says BHE’s Jonathan Weisgall, “The potential is huge.”
The view from the southern end of the ever-shrinking Salton Sea in California’s Imperial County is stark but strangely beautiful. A boat launch is marooned a mile from the far-off glitter of the lake’s edge. Geothermal plants spout plumes of gray steam from their distinctive circular cooling towers.
But it is something out of sight that’s launching activity these days in this desert valley.
Several energy companies are focusing on the Salton Sea’s vast underground geothermal reservoir as a source of lithium – the valuable alkali mineral integral to the batteries used in phones, laptops, electric cars, and everything in between.
Currently, lithium is mined overseas, primarily in South America and China, using extraction processes destructive to the environment. In contrast, the activity at the Salton Sea represents the possibility of having a domestic supply of lithium – and for the process to be green as well as cost-competitive.
To be sure, past ventures at the Salton Sea show how challenging and fraught such endeavors can be. Nevertheless, the underground reservoir here beckons as an untapped, important, and potentially very valuable resource.
“The Salton Sea’s geothermal brine has high concentrations of lithium that are unique in the world,” says Jens Birkholzer, director of the Energy Geosciences Division at the Lawrence Berkeley National Laboratory in California. “It has to be extracted efficiently and cost-effectively, but it could be a huge boon for the area and could also make geothermal more competitive.”
One of the largest liquid geothermal reservoirs in the world is here at the southern terminus of the San Andreas fault. Geothermal energy production began in the area in the 1980s but has encountered setbacks. The drive now is to add lithium production facilities to new or existing plants.
The basics of geothermal
The principle of geothermal energy production is relatively simple: Wells, which can be more than 8,000 feet deep, are drilled down into the reservoir. The pressurized, superheated mineral-rich brine is routed up through pipes to cooling towers where the brine is vaporized. The resulting steam is captured and harnessed to energy-producing turbines.
However, geothermal plants are expensive; a single well can cost up to $16 million, and the overall cost of a commercial plant can top $500 million. Additionally, the cost of wind and solar energy production has dropped dramatically in recent years, rendering new geothermal plants uncompetitive in the energy marketplace.
That’s where lithium comes in. By adding lithium reclamation to the facilities here, there’s a tantalizing opportunity to make geothermal energy production cost-competitive with other renewable power sources.
Reclaiming lithium from geothermal brine is an almost completely green and sustainable process. While the brine is out of the ground for power production, lithium can be extracted, too. The power needed for lithium recovery comes from the geothermal plant itself, and therefore the carbon footprint is minimal. And when the recovery process is completed, the leftover brine is injected back into the depths of the reservoir, where it has time to heat up before being tapped again.
One of the companies that is bullish on this process is Controlled Thermal Resources, an Australian company with operations in California. On a recent day at the Salton Sea, Jim Turner, CTR’s chief operating officer, stands atop a bare windswept hill no longer surrounded by water but still known as Red Island. A muddy playa, or dry lake bed, lies directly below.
“We have about 7,300 acres out there under our control. Our part of the resource goes for about a mile and a quarter past Mullet Island,” he says, pointing toward a distant hump of land that also is no longer an island. “As the sea recedes it will expose more and more playa, which will eventually allow us to complete the development.”
CTR’s proposed new string of geothermal power plants will be the first purpose-built to also produce lithium.
“In addition to a series of replicant geothermal power plants, we’ll have a lithium plant that will produce about 17,000 metric tons of lithium annually,” says Mr. Turner. “The power plants today make money, but they’re not big rates of return. Mineral extraction will make for a much better profit picture for geothermal.”
Geothermal’s salient advantage is that it produces a controlled stream of clean power around the clock. Such a mainline power source could supplement and back up power grids supplied by intermittent renewable energy sources like wind and solar. The geothermal reservoir at the Salton Sea, if fully tapped, could provide power to an estimated 2.3 million-plus homes, and could play a significant role as California tries to reach an ambitious goal of getting 50% of its energy from renewable sources by 2030.
Demand for lithium is expected to grow exponentially as electronic devices proliferate, energy storage demands rise, and combustion engines are increasingly replaced by electric counterparts. The U.S. government has designated the mineral as critical to national security and the economy – and yet currently, lithium comes from foreign regions that in many cases are politically unstable or pose other challenges for the United States.
Damaged ecosystems overseas
Most lithium comes from the so-called Lithium Triangle, which spans Bolivia, Argentina, and Chile. Here, vast man-made evaporative lakes are rich in minerals, but these lakes use enormous and increasingly scarce quantities of water. As a result, desert ecosystems are being destroyed and hardships have grown for local residents. The remaining lithium comes chiefly from China and Australia, where the mineral is extracted from crushed rocks. This hard rock open-pit mining also damages ecosystems, and the toxic chemicals used to process out the lithium can contaminate soil, streams, and groundwater. Moreover, hard rock mining has a large carbon footprint.
Mr. Turner makes distinctions about the impact that CTR’s process would have on the environment. “Ours is a totally closed-loop system,” he says. “Everything’s in pipes and vessels, and you can control the whole thing. We’ll have almost a completely green process here.”
This isn’t the first time that lithium extraction has been tried at the Salton Sea. Energy company Simbol Materials had a pilot lithium production facility that created a lot of excitement; Elon Musk, the Tesla CEO, offered to buy the company in 2014 for $325 million. But the deal fell apart, and Simbol went out of business.
Berkshire Hathaway Energy, which operates 10 geothermal plants at the Salton Sea, also developed mineral reclamation techniques using brine, back in 2002 – for zinc. But two years later after disappointing results, BHE halted zinc reclamation activities. However, the company is again actively interested in mineral recovery – this time, of lithium. BHE is hoping to build a demonstration lithium reclamation plant that would establish the commercial viability of lithium production at its current facilities.
“The potential is huge,” says Jonathan Weisgall, vice president of government relations at BHE. “If this really goes, our existing geothermal plants could produce up to 90,000 metric tons of lithium a year. That would satisfy more than one-third of the entire worldwide demand for lithium today. And everyone agrees that there will be a fourfold increase in demand. There’s a tremendous potential for expansion.”
Yet Simbol’s collapse, as well as BHE’s failed experiment with zinc production, demonstrates the pitfalls. And geothermal brine presents a formidable chemistry problem; it contains corrosive minerals and other contaminants that need to be efficiently separated out to create market-grade lithium.
Still, the benefits of having a domestic and green supply of lithium are numerous, and the lithium resources at the Salton Sea are epic in scale. In fact, if the entirety of this geothermal reservoir were to be fully utilized, the ensuing lithium production would have the potential to not just meet but exceed global lithium demands for years to come.
“If you were to expand the geothermal resource and while also extracting lithium, you could go out to a factor of 5 or 10 times the current world usage of lithium,” says Dr. Birkholzer of the Berkeley Lab. “It would have to be extracted efficiently and cost-effectively, but the resource is clearly there.”