Even as demand soars for lithium and other critical minerals needed to power the clean energy transition, e-cigarette users are tossing millions of tiny batteries’ worth of those elements into landfills each year.

“Five disposable vapes are being thrown away every second by young people in the United States despite the devices containing reusable lithium-ion batteries,” reports the Bureau of Investigative Journalism. “Over a year, this amounts to 150 million devices—which together contain enough lithium for about 6,000 Teslas.”

Lithium is an “in-demand metal” because of its use in rechargeable batteries for mobile phones, electric vehicles, and more—and the need is expected to increase fivefold by 2030, the Bureau says. Lithium-ion batteries are also used in e-cigarettes or vapes to heat the “e-juice” liquid nicotine solution they contain.

“Even though most disposable vapes contain a rechargeable lithium-ion battery, they are designed to be discarded once the liquid runs out.”

Since vapes have become incredibly popular, the impact of this waste [pdf] can be substantial. More than 14 million single-use vapes are purchased in the United Kingdom each month, with more than 50% of them “needlessly being thrown away” after their 3,500 or so puffs are exhausted, said Scott Butler, executive director of Material Focus.

“This means that every week one million vapes are not recycled,” he added.

On top of the wastage, discarding batteries combined with other mixed garbage pose a real danger of fires at waste processing sites. One U.S. Environmental Protection Agency report identified 245 fires between 2013 and 2020 that were definitely or likely caused by lithium-ion batteries in waste facilities like garbage trucks and warehouses.

“One incident resulted in four firefighters being taken to hospital to be treated for chemical burns,” writes the Bureau.

The batteries are meant to be recycled, but the process can be a difficult and confusing, with some vapes needing to be taken apart to properly do so. Regulatory oversight has so far proved insufficient to ensure disposal guidelines are being followed and that manufacturers are complying with collection requirements.

As a result, more and more vapes find their way into landfills, where critical minerals accumulate instead of being used for the energy transition. One calculation described the critical minerals from vapes discarded in the UK over one year as “equivalent to 6,200 Tesla Model 3 batteries being driven once and then thrown away,” or 617,000 e-bike batteries.

“Every one of the batteries that are in a vape like this holds about one-third of the battery that’s in your phone,” Alex Fairclough, an engineer who teaches at Newcastle University, told VICE. “The fact that we’ve got hundreds of millions of these things just getting put into a $20 vape that gets thrown in the bin, it’s tragic.”