Since oil and gas drilling began nearly 150 years ago, the salty wastewater it produces has been a nuisance for operators.

Now, the electric vehicle revolution could turn the industry’s billions of barrels of brine into dollars. Oil and gas companies are eyeing their own byproduct — along with naturally occurring brine found deep underground — as a source of lithium, a highly sought-after metal needed to make EV batteries.

Industry executives and experts say companies are close to bringing to market technologies that extract lithium from brine in producing wells, creating a new revenue stream in an energy transition that’s threatening the oil industry’s bottom line.