Geothermal Brine Pretreatment and Metal Recovery
Project Update
The project team has completed coordinated laboratory testing to identify specific parameters of processes that can be used to selectively separate constituents from geothermal brine. Core activities focused on implementing the lab‑scale test plan, conducting experiments with sequential precipitation, developing novel electrowinning and additives recovery approaches, and preparing infrastructure for pilot‑scale operations. Engagement with external partners and participation in the EPIC Symposium supported broader dissemination and alignment with industry needs.
The Issue
Lithium is a high-value metal used in the production of lithium rechargeable batteries which are a key technology for the clean energy transition. Lithium is found in low but significant concentrations in some geothermal waters. For example, there are a few hundred milligrams per liter in the Salton Sea known geothermal resource area. Because of the very large volume of brine processed in a geothermal power plant (>22,700 liters per minute), even low-lithium brines represent a valuable resource. A direct extraction process can recover lithium from geothermal brines without the large footprint and negative ecological impact of mining or evaporation ponds that are the two traditional methods of lithium production. However current brine treatment processes result in leftover solid waste products containing silica, iron, and toxic minerals, including lead and arsenic, that require landfill or costly hazardous waste disposal. Reduction of these solid waste products is needed to lower operating costs while improving mineral recovery.
Project Innovation
The project is developing a geothermal brine treatment process based on metal sulfide precipitation. This process will not only remove interfering species and enable direct lithium extraction but will also allow the recovery of valuable critical minerals like zinc and manganese from the geothermal brine. The inclusion of sulfur recovery and recycling in the geothermal brine treatment process will significantly improve process economics and reduce waste streams and the need for chemical additives. The project also advances innovation in geothermal brine processing, particularly by developing a novel manganese electrowinning system with higher efficiency than conventional methods. The continuous acid–salt separation system represents a significant improvement over commercial batch processes, offering potential gains in sustainability and cost reduction.
Project Goals
Project Benefits
This project will lead to lower costs of geothermal power production and an increased share of clean and renewable geothermal power in California. It will also help spur a new industry of lithium and other critical minerals production that will provide much needed materials for battery manufacturing with significantly less impact to the environment.
Affordability
Developers in the Salton Sea known geothermal resource area report they can reduce the cost of geothermal power by 35 percent to be sold at $50 per megawatt hour by integrating lithium recovery with geothermal power production.
Reliability
A domestic source of minerals used in batteries will lead to greater market stability as production of electric vehicle batteries increases.
Key Project Members
Subrecipients
Match Partners
