Scientists just discovered an enormous lithium reservoir under Pennsylvania

Scientists have discovered a vast reservoir of untapped lithium hiding in wastewater from a Pennsylvania gas fracking site. 

The wastewater, produced by the hydraulic fracturing of rocks inside the Marcellus Shale gas wells, contains enough lithium to supply up to 40% of U.S. demand, according to the new study published April 16 in the journal Scientific Reports.

"We just didn't know how much was in there," Justin Mackey, a researcher at the National Energy Technology Laboratory, said in a statement. 

Currently, 90% of the world's $8 billion lithium supplies are produced in Australia, Chile and China. The rare element is essential for the production of electric vehicle batteries, smartphones, laptops, smartwatches and electronic cigarettes, and demand for it is currently booming, with prices surging by roughly 500% year on year. 

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Right now the U.S. has only one operational lithium mine — in Nevada — meaning huge quantities of the element must be imported to meet demand. However, given the importance of lithium for current plans for a green energy transition, U.S. Department of Energy officials have set a target for all lithium used in the U.S. to be produced domestically by 2030. Currently, more mines are scheduled to open in states such as Nevada, California and North Carolina. 

Yet lithium mining remains controversial as it can release carbon dioxide into the atmosphere and destroy natural environments by leaking toxic chemicals into soil.