DW - Paul Krantz

Excerpt:

Three large mining projects based in California's "Lithium Valley" aim to recover lithium with minimal environmental impacts. They have the potential to simplify the global lithium supply chain.

Michael McKibben, a geochemist and research professor at University of California Riverside, leads a study analyzing lithium resources in the area.

"I've taken both a conservative approach and an optimistic approach to estimating the amount of lithium," McKibben told DW. "It's somewhere between 1 and 6 million metric tons of dissolved lithium metal in the brines." (Or a lithium carbonate equivalent of 5 to 32 million metric tons.)

According to McKibben, that makes this area one of the top lithium brine deposits in the world.

Three companies are racing to tap into this immense lithium resource. If their projects succeed, they will establish a method for extracting lithium without the negative impacts of conventional lithium mining.

The three companies involved are Energy Source Minerals, Berkshire Hathaway Energy (BHE), and Controlled Thermal Resources (CTR). Energy Source Minerals appears to be the closest to their goal. They aim to collect battery-grade lithium at commercial scale by 2024. Berkshire Hathaway Energy has set 2026 as a goal for beginning commercial production. Controlled Thermal Resources has gained investment backing from General Motors.

With its drilling rig in Calipatria and other renewable energy projects, CTR has gained a headstart in green lithium mining

What sets these projects apart from conventional lithium mining is their connection to geothermal power plants, 11 of which are already established in the area. Geothermal plants pump up hot brine from underground and use the steam to generate electricity before re-injecting the brine back into the ground. Now they will add one more step — removing lithium from the brine before it's re-injected.

"It's important not to call it mining," said McKibben, who prefers the term "lithium recovery," because compared with conventional lithium mining, this process has minimal environmental impacts.

Conventionally, lithium is extracted in the form of hard rock, or from salts collected in solar ponds.

Hard rock lithium mining involves digging vast, open pits to pull out rocks like spodumene, which then need to be roasted and dissolved in acid. It's a fossil fuel-intensive process, and has a devastating impact on the local environment. The vast majority of hard rock mines are in Australia, and to a lesser extent, China and Africa.

Salar pond mining involves pumping brine to the surface and leaving it in shallow pools. After the water evaporates, lithium-rich mineral salts remain. Salar ponds, also called salt evaporation ponds, take up thousands of square kilometers and deplete groundwater reserves, especially in desert regions where local populations depend on them. This method is most prevalent in Argentina, Chile and Bolivia.

Compared with salar ponds or hard rock mine pits, a geothermal power plant is relatively small, so direct lithium recovery projects require much less land use. The process avoids both the destruction and waste created by hard rock mining. It has a much smaller effect on groundwater sources than solar pond mining, because brine is re-injected into the ground after its use.

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