Electric vehicles make up just 1% of the car market today, but by 2040, experts are predicting half of all cars sold will be electric. Volvo has pledged to only manufacture EVs or hybrids from 2019 on ; Volkswagen wants to release 30 new EV models by 2030.

What’s really holding them back for the time being is price, mainly due to the lithium-ion batteries necessary to power them. But as manufacturers like Tesla, whose Nevada-based Gigafactory will produce 35 gigawatt-hours of batteries each year by 2020, begin to scale up EV battery production, their costs will fall.

But as the EV battery industry balloons, it raises a question: How will it get its hands on enough lithium to maintain demand?

Lithium, the crucial ingredient in lithium-ion batteries, is a naturally occurring element found primarily in the brine of the salt flats of South America, China, and the United States. Traditionally, extracting lithium from the flats involves transferring brine to massive aboveground ponds; once the water evaporates out, the lithium is chemically separated from the salt, which is left out on in the landscape in quantities large enough to become toxic to plants and animals. The whole extraction process takes around two years, only captures around 50% of the lithium present, and drains already-dry landscapes of water.

As the battery industry expands, it can’t afford to continue to degrade the environment to extract this element, nor can it afford to lose half of the available lithium in the process. The resource is not infinite, and as more and more of it is pulled from the land, it’s becoming increasingly difficult for mining companies to locate lithium-rich areas from which to extract the element.