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If all goes as planned, solar, wind and other clean energy technologies will help us abandon carbon emissions for good. But many green power sources perform their best only when nature cooperates, so an important (and sometimes overlooked) component of the energy transition is the ability to store electricity for a rainy or calm day. Lithium is the ingredient of choice for electric vehicle batteries, solar panels and grid elements. As these innovations ramp up, lithium demand is expected to soar by 90% over the next two decades, driving a surge in production efforts. Some experts predict a deficit in the mineral by as soon as 2025.
Predominant mining and extraction processes can be detrimental to the surrounding air, soil and water, in contrast to the environmentally friendly intentions of the lithium applications. But another type of renewable energy may be able to provide a solution. Hydrothermal brine, a high-saline water mixture found deep within the Earth’s crust, contains lithium-rich deposits that have leached from heated rocks into underground water. Geothermal power players employing hydrothermal brine are spearheading plans to extract the valuable resource in a cleaner and more sustainable manner.
Why Lithium?
First commercially developed around 1985, the lithium-ion battery quickly overtook other types of batteries due to its high storage capacity. Its creators even won a Nobel Prize in 2019. As electric vehicles have come to the forefront of the energy transition, technological breakthroughs have only made these batteries more efficient and versatile. Clean technologies like wind farms and solar plants, some of the fastest growing energy sources, rely on lithium-based storage. The International Energy Agency (IEA) reported that compared to 2010, 50% more minerals are now needed, on average, per new unit of power generation capacity—due in major part to the rising use of low-carbon innovations.
The United States has responded to the demand with the Department of Energy’s (DOE) 2021 National Blueprint for Lithium Batteries, which states that “by 2030, the United States and its partners will establish a secure battery materials and technology supply chain that supports long-term U.S. economic competitiveness and equitable job creation, enables decarbonization, advances social justice, and meets national security requirements.” The Biden Administration has also cited over-reliance on foreign supply chains as a reason for boosting domestic lithium production. Meanwhile, the EU recently signed strategic partnership agreements with 12 countries for rare minerals, and in March, it finalized the Critical Raw Materials Act (CRMA). The law named 34 critical elements, and lithium is among the 17 elements specified as being of absolute strategic importance.
A New Extraction Plan
Lithium is found in a handful of sources: minerals, clays, oceans and brines (salt flats, geothermal brines, and oil fields including the Arkansas Smackover), with brine sources accounting for 66% of the world’s present supply. It is extracted in the form of lithium carbonate, which is then processed so it can be used in our modern gadgets. South America is a major producer; in the region’s salt flats, or “lithium deserts,” saline groundwater is pumped to the surface and evaporated in large basins, where the water leaves behind salts that include lithium. The process is water-intensive and the lithium recovery rate is low. Australia and China are also leading producers and primarily use open-pit mining of hard rocks, including the lithium-bearing material. With current supplies coming almost entirely from China, Australia and Chile, U.S. leaders have set their sights on accessing domestic lithium via sites like California’s Salton Sea region. And under the CRMA, Europe aims to produce 10% of lithium domestically by 2030. Currently, the region’s only active lithium mine is in Portugal.
So far, evaporated and open-pit lithium extraction processes have been the “greenest” options available. But now, geothermal plants could offer a more sustainable possibility through a process known as direct lithium extraction (DLE). Geothermal energy, a rising star in the green energy movement, has a small physical footprint, virtually no carbon emissions, is not weather reliant and, as it turns out, can do double duty as a lithium resource. Geothermal electricity works by pumping hot salty water, or brine, up from thousands of feet below the Earth’s surface and turning it into steam that powers turbines. The water is then recirculated into aquifers. That same power-producing brine contains lithium that can be extracted before reinjection of the liquid, and the process can be repeated over and over until the brine is too diluted to continue. Though lithium exists in small concentrations within the brine, the large scale of geothermal power production could yield a significant output. By one estimate, California’s existing geothermal plants can produce enough lithium to fully meet U.S. demand, with plenty more to spare for exports.
Projects on the Horizon
On a global scale, projects and research that aim to take advantage of the lithium in geothermal brine are well underway.
- Europe: A 2023 study published in Advances in Applied Energy reported that pilot plants in the Upper Rhine Graben region of France and Germany, an area with natural geothermal reserves, show promising results. The study noted that while geothermal operation costs will likely not drop as low as solar or wind, the revenues from lithium can offset expenses, offering a cost-effective and energy efficient solution. Vulcan Energy Resources has announced plans to start phase one of its geothermal and lithium extraction plant in this region of Germany. In addition, in the famously beautiful, coastal county of Cornwall in the United Kingdom, companies are collaborating on a demonstration project that will combine hydrothermal power with lithium extraction. The pilot will focus on a range of DLE technologies.
- United States: The Salton Sea region, a swath of California lake and desert that is brimming with rich geothermal activity deep below the surface, is home for at least a dozen geothermal power plants. The existing plants mean that a significant portion of the infrastructure is already in place to extract lithium. In January 2024, Controlled Thermal Resources began construction of a new facility in the area that will output both power and lithium, starting with 25,000 metric tons of lithium and ultimately producing up to 175,000 metric tons. At the John J. Featherstone geothermal plant in the Salton Sea, EnergySource Minerals has partnered with Ford to produce lithium in a closed-loop, sustainable process; the new approach is projected to allow the company to tap into an existing geothermal plant and remove lithium from brine that has already been used to generate geothermal power.
On a national scale, the DOE recently awarded its $4 million Geothermal Lithium Extraction Prize to five teams who will use the funds toward increasing market viability for direct lithium extraction from geothermal brines. The National Renewable Energy Laboratory also reported that additional lithium extraction technologies are approaching commercial-scale demonstrations by operators in the Salton Sea.
The chief obstacle for American brines is that impurities such as magnesium and calcium interfere with DLE lithium recovery. Recently, lithium extraction technology, using chemical reactions different from DLE, has been developed in South Korea and its efficiency and economic feasibility using the American brines has been validated. This CULX technology is expected to produce substantial additional quantities of lithium to support American energy transition demand.
Looking Ahead
A California State Legislature commission on lithium extraction reported in 2022 that the Salton Sea region likely contains the world’s highest concentration of lithium in geothermal brine, a finding that could be a major boost to zero carbon goals for the United States and beyond. Researchers across the globe are also looking to tap into geothermal technology for lithium recovery, but innovating and scaling up such operations pose challenges. As Lawrence Berkeley National Lab researcher Dr. Patrick Dobson noted, “The key challenge now is to develop the science of extracting lithium from geothermal brines in a cost-competitive and environmentally friendly manner.” Environmental impact studies, paired with development of technologies that will make DLE economically viable, will be key steps to moving forward. The two-in-one nature of geothermal resources—electric or thermal power plus a key mineral for electric power generation and storage—is an appealing energy transition solution for governments and entrepreneurs alike.
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