Thousands of tons of trash from across the Twin Cities ended up in landfills instead of being incinerated to make electricity last year, despite a state law that prioritizes burning over burying.

But that 30-year-old law has never been enforced — until now.

State regulators are pressing the companies that collect and dispose of metro area trash to fill the area's incinerators before heading to landfills, a shift that has met with resistance and even a legal challenge. Meanwhile, the burners at Great River Energy's waste-to-energy plant in Elk River run below capacity, and lack of trash forced Red Wing to close a small incinerator at its processing facility several years ago.

"There's no reason for us to be putting this amount of waste in the ground when we have facilities that are built and operating that can handle it," said Sigurd Scheurle, planning director with the Minnesota Pollution Control Agency (MPCA).

Facilities that take trash for incineration had enough unused capacity in 2016 to handle about 14 percent of the trash that went to metro area landfills, according to data provided by the MPCA and Great River Energy.

Redirecting trash for burning poses challenges, however. There are hundreds of companies involved in hauling and processing trash in the metro area. And facilities that accept the trash — landfills and waste-to-energy sites — charge different prices per ton dropped off.

"It has literally put the whole industry in turmoil like it's never been," said Bill Keegan, who chairs the Minnesota chapter of the National Waste and Recycling Association. "Nobody knows how to do this, nobody even knows how to enforce it."

Houston-based Waste Management, the nation's largest waste firm and owner of three of the four primary landfills that take metro area trash, tried unsuccessfully to block enforcement in court several years ago.

Waste Management spokeswoman Julie Ketchum said requiring waste to be redirected to another private company amounts to a violation of federal law — though the MPCA disagrees. The Great River Energy waste-to-energy facility is near one of Waste Management's landfills.

"In essence, we are being asked to support a competitor," Ketchum said.

Tim Steinbeck of Great River Energy, a cooperative energy company, said they are losing millions of dollars a year on the Elk River operation, a cost borne by their member owners. Those facilities, which process trash and incinerate it, operated at about 80 percent capacity last year.

"It is a bit awkward, we readily admit that," Steinbeck said. "Yes, we are effectively a private business. But we're funded by all Minnesota consumers in their electric rate, mostly outside the metro."

Incineration controversy

About half the trash from the seven-county metro area is recycled or composted. But 23 percent of it went to landfills in 2015, while another 28 percent was processed for incineration.

Waste-to-energy facilities generally remove recyclable metals and grind up trash for burning, though Hennepin County's downtown Minneapolis facility accepts the waste whole and removes metals after burning. The resulting ash, which is sent to landfills, is about one-tenth the volume of the original garbage.

But incineration has long been controversial because of air pollution emitted by the plants. MPCA data show that the Hennepin County Energy Resource Center (HERC) is one of the largest point-source emitters of nitrous oxide, lead, particulates and carbon dioxide in Hennepin County, for example. Those emissions are far below the MPCA's limits, however, and the agency said waste-to-energy emits less than other power generation methods.

Margaret Levin, state director of the Sierra Club North Star Chapter, said the incinerators also work against the larger goal of waste reduction.

"There's a demand for them to be at capacity," Levin said. "And for us that has the effect of discouraging or disincentivizing recycling and reuse and reductions."

MPCA assistant commissioner Kirk Koudelka said the agency agrees recycling and composting are the first priority. But it prefers burning what remains to produce energy, in part because of the recyclables recovered in the process.

Where does it go?

Garbage haulers decide where to take trash based on facilities' prices, proximity and company preference, according to a 2012 MPCA report. For instance, Waste Management and Republic Services own collection trucks that can haul trash to their own landfills.

Processing trash for burning is generally more expensive than landfilling, so subsidies have helped facilities remain competitive over time.

Ramsey and Washington counties have used subsidies to lure more haulers to a private processing plant in Newport, but recently decided to purchase it and require waste to be delivered there — something that can only be done for public facilities. Great River's fee per ton at Elk River is higher than the fee at two other large processing plants in the Twin Cities, in part because subsidies from Hennepin and Anoka counties have recently dried up.

Ketchum, of Waste Management, said Great River needs to lower its prices to attract more trash to fuel its burners. And, she said, the state is unfairly targeting landfills to enforce the law. Landfill permits issued last year include the restriction on accepting trash that could be processed for incineration.

According to the MPCA report, a Waste Management landfill 10 minutes down the road from Great River Energy could see its deliveries drop 29 percent if the law is enforced.

The landfills, Keegan said, are "screaming, saying, 'Hey, how can I stop them? What do I do? Who do I turn away? Do I turn away hauler A or hauler B?' "

An industry group has studied options for reaching compliance, from having the state subsidize waste-to-energy costs to requiring haulers to take a percentage of their trash to those facilities, but would likely need action from the Legislature to pursue them.

The MPCA's Koudelka downplayed the logistical challenges of shifting the trash needed to keep burners running. The gap at the Great River Plant could be met with the waste being trucked from Anoka County to area landfills.

"They're driving right past the waste-to-energy facility," he said.

Eric Roper • 612-673-1732 Twitter: @StribRoper