by Will Sarni
To a significant degree, the future of renewable energy is tied to lithium, and the race is on to secure abundant and reliable resources of this metal.
A low-carbon future requires lithium-ion rechargeable batteries for electric vehicles and the storage of power from renewable sources, such as solar and wind energy. Indeed, the market for lithium-ion batteries is projected by the industry to grow from $30 billion in 2017 to $100 billion in 2025.
An emerging source for high-value lithium is in geothermal brine — “a hot and concentrated saline solution enriched with minerals, such as lithium, boron and potassium.” Despite the relatively low concentrations that can be encountered (a few hundred parts per million) present in these brines, the very large volume of brine processed in a geothermal power plant (hundreds of cubic meters per hour) makes brine a valuable potential resource. However, the current approach to extracting lithium from brine involves evaporation ponds, which is complex and inefficient. As a consequence, only about 30 percent of the lithium in the original brine reaches the marketplace.
The opportunity for increasing lithium production from geothermal brines was outlined in a 2020 report prepared by the California Energy Commission. The analysis outlined the opportunity to extract lithium from geothermal brines in California and discussed an expected benefit of improving the economics of geothermal energy production by generating revenue from the production and sale of lithium carbonate.
The increasing demand for lithium has also created an opportunity for the development of innovative treatment technologies to extract lithium from brines.
For example, the primary author of the California Energy Commission report, research institute SRI International, demonstrated a new process for the extraction of lithium from geothermal brines based on “new high-capacity selective sorbents (material used to absorb or adsorb liquids or gases) and a new sorbent regeneration process.”
Compared to traditional methods of recovering lithium from brines, “SRI International’s sorbents and regeneration processes are expected to reduce the cost of lithium production by allowing online separation with higher recovery efficiency and using smaller volumes of sorbent, minimizing processing time. The project team demonstrated extraction of lithium with efficiency as high as 90 percent and detected no significant loss in capacity after repeated lithium adsorption-desorption cycles.”
Other examples of innovative treatment technologies come from companies including Evove, based in the U.K., and EnergyX | Energy Exploration Technologies, based in the U.S. Advances in membrane technology have been a major area of focus in the water sector, driven by the need to turn brackish or saline water into fresh water for consumption.