Mammoth Hot Springs at Yellowstone National Park.

In the 20th century, access to fossil fuels determined the fate of nations, from world wars and cold wars, to energy crises and state-sponsored terrorism.

But a coming energy shift could mean that lithium, the substance used to treat psychiatric conditions and in nuclear weapons, could become one of the key natural resources of the 21st century due to the needs for battery storage.

A team at Stanford has now written that supervolcanoes could be the new major source of the element in years to come. The U.S. could be especially primed well for that future, based on the three supervolcanoes known on American soil, they explain in a new study in the journal Nature Communications.

“We’ve had a gold rush, so we know how, why and where gold occurs, but we never had a lithium rush,” said Thomas Benson, the lead author, a recent Stanford doctoral graduate. “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.”

The investigation of lithium deposits began in 2012. The Stanford authors looked into the magma of supervolcanoes from six sources: the Kings Valley deposit on the Nevada-Oregon border, the High Rock caldera in Nevada, the Sierra la Primavera in Mexico, the Pentelleria off Sicily, Yellowstone in Wyoming, and Hideaway Park in Colorado.

Although the volatile element is difficult to measure, they assessed tiny bits of the original magma that were trapped in crystals from growth within the ancient magma chambers – a phenomenon called “melt inclusions,” they report in the journal.

Cutting into the crystals to assess the fragments (which were at most 100 microns in diameter) allowed the scientists to look into the lithium itself, using high-tech tools at the Sensitive High Resolution Ion Microprobe-Reverse Geometry (SHRIMP-RG) Laboratory at Stanford.

Their results showed the lithium was plentiful enough to warrant economic interest, even where the magma itself didn’t show high density of the element, they report.

Geologic markers also showed a way to locate lithium concentrations for future harvesting. More rubidium generally pointed toward more lithium, while more zirconium heralded less lithium, they report.

But the supervolcanoes overall showed to be a rich source of future components for lithium-ion battery storage, they found.

“The caldera is the ideal depositional basin for all this lithium,” said Benson.

Currently, the major sources of lithium are salt flats in Chile, and certain deposits in Australia.

But American supervolcanoes – the three major ones include the Yellowstone Caldera, the Long Valley Caldera in California, and the Valles caldera in New Mexico – could provide the U.S. with a natural advantage, the Stanford scientists report.

“We’re going to have use electric vehicles and large storage batteries to decrease our carbon footprint,” said Gail Mahood, one of the authors, a Stanford professor of geological sciences. “It’s important to identify lithium resources in the U.S. so that our supply does not rely on singles companies or countries in a way that makes us subject to economic of political manipulation.”

Predictions about lithium battery power indicate it could be a future driver of the 21st century economy. For instance, a forecast published last month found that improvements in storage technology could make electric vehicles as cheap as gasoline powered cars in about a decade.