Researchers from the School of Engineering & Applied Sciences published a study assessing the viability of an alternative lithium extraction method that releases fewer chemicals last month.
Lead researcher Xitong Liu, a professor of civil and environmental engineering, detailed a new technique to extract lithium — the alkali metal used in rechargeable batteries and electric vehicles — from lithium ions of geothermal brine, building on an initial design he proposed in 2023 for a Department of Energy contest. Liu said his team determined that his method is economically viable, and he said he hopes the concept of isolating lithium ions in extraction will mitigate the environmental cost of current lithium extraction methods by lowering carbon emissions.
“Our study demonstrates a sustainable and efficient alternative to conventional lithium extraction methods,” Liu said in an email. “By leveraging geothermal brine, we can reduce environmental impacts, lower carbon emissions, and provide a reliable lithium supply for the growing battery industry.”
Liu and other researchers won $50,000 from the American-Made DOE Geothermal Lithium Extraction Prize for this alternative method in December 2023.
The International Energy Agency predicts total lithium demand will triple by 2030, which Liu attributed to the heightened prevalence of electric vehicles. Liu said the increased demand poses concerns for the environment because conventional, energy-intensive extraction methods release carbon dioxide into the air, while his new method reduces emissions.
“Current research is advancing, but more information is needed to meet future demand sustainability,” Liu said. “Efforts are focused on improving extraction efficiency, reducing environmental impacts, and exploring alternative sources like geothermal thine and oil/gas produced water.”
The hike in demand has caused geothermal brine, historically a waste product brought up by geothermal energy production that scientists reinject into the ground after extracting, to emerge as an alternative source of lithium due to the high concentration of lithium within the fluid.
According to Berkeley Lab, companies typically extract lithium from geothermal brine by separating it using adsorption, a phenomenon in which ions from a fluid adhere to a solid surface. The lithium is captured via an injection well, converted into lithium chloride and then into lithium hydroxide, the form of lithium used by electric vehicle manufacturers.
Liu said the extraction method his team developed expands on the conventional methods by selectively extracting lithium ions from the brine to avoid capturing unnecessary chemicals and minerals including sodium and calcium, thereby reducing the amount of chemicals released in the process.
“We developed a novel electrochemical process using selective lithium-ion capturing electrodes,” Liu said. “These electrodes are designed to preferentially bind lithium ions from the complex mixture of minerals in geothermal brine.”
Liu said while the research outlines the method’s success, companies will still face challenges scaling-up production to the levels needed to meet growing lithium demand. He said further research is needed to see how this method can be accommodated for larger scales.
“This method has the potential for scalability,” Liu said “It can be integrated into existing geothermal power plants, leveraging their infrastructure and energy supply. However, further optimization and pilot-scale testing are needed to ensure economic viability and efficiency at larger scales.”
Geologists and engineers said Liu’s team’s new method of geothermal extraction could have a positive environmental impact in the sector because extraction from geothermal brine has a reduced ecological footprint since it eliminates the need for drilling and blasting into the Earth.
Traditional lithium extraction techniques, like hard-rock mining from salt flats, have historically had a detrimental environmental impact, with lithium hard-rock mining producing 15 tons of carbon dioxide per ton of lithium mined, according to a 2022 Massachusetts Institute of Technology study.
Michael McKibben, a professor of geology at the University of California, Riverside, said compared to hard-rock mining, geothermal extraction streamlines the process by utilizing the geothermal brine to process the lithium ions rather than having it be a waste product that has to be reinjected into the ground.
“Pulling lithium out of brines, like geothermal brines or oil filled brines, is comparatively more straightforward and less environmentally damaging because you’re already bringing the brine to the surface anyway, as part of the geothermal power cycle or as part of the oil field operations,” McKibben said. “So you’re just taking what normally is considered a waste material and processing it for lithium.”
McKibben said while the method developed by Liu’s team presents a more environmentally friendly approach to geothermal lithium extraction, its financial and practical viability is uncertain because engineers need equipment that is able to handle the volume of brine needed to extract the lithium, which could be costly. McKibben said though Liu’s study may have worked in a smaller-scale lab setting, the effectiveness of the method may change with larger volumes of brine.
“They produce out of the geothermal field at the Salton Sea, 50,000 gallons of brine per minute. So you have to be able to have an absorbent that will process that much brine that quickly, at very high temperature and very high salinity,” McKibben said. “And so the question is, has the GW lab experiment been shown to work under those conditions?”
Sandeep Kumar, a professor of civil and environmental engineering at Old Dominion University, said investing in domestic infrastructure for geothermal lithium extraction could reduce American dependency on global lithium suppliers.
“You can see the exponential growth in electric vehicles coming up. Batteries are being tested every most of the applications,” Kumar said. “So electrification is going on. So with that, lithium demand is going to be huge. And one of the strategic needs of the United States is having your own resources at home.”
