An Untapped Resource

Whether you're scrolling through cat memes on your phone, writing a glowing Game of Thrones review on your laptop, or running out to grab a coffee in your electric car, modern life relies on lithium — most likely, lithium mined in Australia or Chile. But a new study suggests future electronic devices could be powered by lithium from an explosive source here in America: supervolcanoes.

Published today in Nature Communications, the research from scientists at Stanford University investigated lithium laid down by these unusually large volcanic eruptions, which eject more than 1000 cubic kilometers of magma.

The researchers analyzed rock samples from several lithium-rich sites, including the McDermitt volcanic field on the Nevada-Oregon border, where several supervolcanic eruptions originating in the Yellowstone hotspot occurred between 16.5 and 15.5 million years ago.

They found these crusts had an average lithium concentration of about 1,300 parts per million. Compared to other, non-supervolcanic deposits the team examined, this concentration is relatively low. However, when they erupt, supervolcanoes produce roughly one to two orders of magnitude more magma than other volcanoes — scaling the concentration up such that, with higher volume, significantly more lithium is available in total.

The Kings River Valley, home of one of the largest lithium deposits in the US. Image credit: Famartin, Wikimedia Commons

For Long Ridge alone, one of the regions in the McDermitt field the researchers analyzed, the volcanic eruption produced as much as two million megatons of lithium. Over the years, a fraction of that lithium would seep out of the magma as the volcanic crater filled with water and concentrate within volcanic clay. The authors don't yet know how much lithium that leaves for us to viably extract, but suggest that it is "significantly greater in large caldera settings than in the more Li-rich but smaller eruptive systems."

In analyzing these samples, the researchers also discovered a previously unknown correlation between lithium and easily-analyzed trace elements: For example, it turns out that a higher abundance of rubidium indicates there is more lithium in a deposit, while high concentrations of zirconium suggest less lithium.

"Now that we have a way to easily find more of these lithium deposits, it shows that this fundamental geological work can help solve societal problems," said lead author Thomas Benson, a recent PhD graduate from Stanford Earth. "That's really exciting."

Mining an Electric Future

Lithium is already classified by several governments as an energy-critical element, due to demands for low-cost, high energy lithium-ion batteries for portable electronics, electric vehicles, and large power grids.

With more and more car makers producing hybrid and electric vehicles — and some, like Volvo, swapping over to electric entirely — the demand for lithium-ion batteries is set to increase. Globally, humans currently use about 32.5 kilotons of lithium per year. Yet Benson estimates that by 2050 that demand will grow to between 3 and 35 megatons, while the current reserve of lithium we can feasibly extract is only around 14 megatons.

"We've had a gold rush, so we know how, why and where gold occurs, but we never had a lithium rush," Benson said. "The demand for lithium has outpaced the scientific understanding of the resource, so it's essential for the fundamental science behind these resources to catch up."

Lithium is primarily extracted from three places; pegmatite rocks, brine deposits, and clays. The left-hand map shows worldwide deposits as well as the locations of volcanic systems analyzed in this study (black squares). The map on the right shows sites in the McDermitt field analyzed in this study. (Image Credit: Benson, Coble, Rytuba and Mahood.)

Presently, the lithium market is dominated by Australia and Chile, where more than three quarters of the world's lithium is produced. If the US wants to get ahead in the sustainable energy market, having a domestic source would prove a huge boon.

"We're going to have to use electric vehicles and large storage batteries to decrease our carbon footprint," said study co-author Gail Mahood, a professor of geological sciences at Stanford's School of Earth, Energy & Environmental Sciences. "It's important to identify lithium resources in the U.S. so that our supply does not rely on single companies or countries in a way that makes us subject to economic or political manipulation."

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