Minneapolis residents can no longer dispose of batteries in bags atop their recycling carts, due to growing concerns about rechargeable batteries starting fires.

The change is part of a broader Hennepin County effort to have residents bring rechargeable batteries directly to its hazardous waste sites, rather than collecting them curbside or in government buildings. The potential hazards of lithium batteries became clear this October, when a building fire was narrowly avoided at a library in Mound after a discarded vape pen began heating up in a bin.

Minneapolis previously told residents to put all batteries in a plastic bag on top of their recycling bins. It now says residents should put alkaline batteries in the trash and take rechargeable batteries — which are fire-prone — to one of the county's hazardous waste drop-off sites in Bloomington or Brooklyn Park.

Other safe disposal sites for rechargeable batteries, including Home Depot locations, can be found at call2recycle.org. There's no change in Ramsey County, which had already been asking residents to bring batteries to its hazardous waste sites for recycling.

Minneapolis collected about 22 tons of batteries last year, according to a recent city presentation at a waste conference. Alkaline batteries comprise about 75% of the batteries Minneapolis collects, said David Herberholz, the city's director of solid waste and recycling.

Those batteries were collected with the recycling, but the county was taking them to an industrial landfill, said Paul Kroening, Hennepin County's supervising environmentalist. Past efforts to keep them out of the garbage were driven by concerns over mercury, which is no longer used in alkaline batteries.

"The alkaline batteries weren't getting recycled," Kroening said. "We were just disposing of them in a manner other than just having you throw them in the garbage."

Kroening said that because the county wanted to collect the rechargeable batteries, it was simpler to take alkaline batteries as well to avoid confusion.

The city had been taking all the batteries to Momentum, the county's contractor that sorts and packages them, Kroening said. But that posed a fire risk, he said, because batteries were accumulating in storage before arriving at the facility.

Herberholz said the county instructed the city to change its pickup process by December 2.

"This is Hennepin County's program, and we follow suit with them," Herberholz said.

Fires caused by lithium batteries are a growing concern for recycling facilities across the nation. Bill Keegan, president of Dem-Con Companies, said the recycling industry is losing one facility per month to fires caused by batteries. One of them was Dem-Con's own Blaine transfer station, which was destroyed last year by a battery fire.

Keegan, who chairs the Minnesota chapter of the National Waste and Recycling Association, said Hennepin County's decision to stop collection at many drop-off locations could have unintended consequences such as sending more batteries into the waste stream.

"We need to have better messaging about what to do with the batteries," Keegan said. "And we need to increase the drop-off locations and take-back infrastructure for these batteries, so that they're not ending up in the trash and recycling."