Minnesota Regulators Open Door for Waste and Wood-Burning Plants to Count as 'Carbon-Free'

Power plants that burn municipal trash or wood waste can qualify as carbon-free under Minnesota's 2023 clean energy law, state utility regulators decided on Thursday after a contentious hearing.

The law requires all electricity generated in Minnesota to come from carbon-free sources by 2040, part of an effort to sharply reduce the state's greenhouse gas emissions. It defines carbon-free as a technology that generates electricity without emitting carbon dioxide, but it does not list which technologies meet that standard. Lawmakers left that question to the Minnesota Public Utilities Commission, which has spent the years since holding proceedings on how to carry out the law.

Wind and solar are straightforward cases because they produce power without greenhouse gas emissions. Plants that burn municipal waste or wood waste are harder, since they release significant amounts of greenhouse gases. Supporters of burning those materials note that wood left to rot gives off carbon dioxide and that landfilled trash releases methane, a potent greenhouse gas.

The commission's five members voted to let such facilities qualify if they pass a life-cycle analysis showing that burning the material there produces fewer greenhouse gases than the most likely alternative way of disposing of it. The meeting was interrupted twice by protesters who repeatedly shouted, "This is not the bill the people passed!"

Commissioner Audrey Partridge offered a hypothetical in which a Minnesota county gathers wood waste from forests damaged by storms and insects. The county recycles 10 percent of it and burns the rest to keep the infestation from spreading, releasing 100 tons of carbon. If a utility could burn the same wood for power and a life-cycle analysis found the result would be under 100 tons, it would count as carbon-free. "If taking this waste and using it to generate electricity provides a climate benefit, then it should qualify," Partridge said.

Several environmental groups disagreed. DFL Sen. John Marty of Roseville, a co-author of the law, was among 42 legislators who signed a letter urging the commission to exclude biomass and waste incineration. "I urge you to follow the plain wording of the law and the vision the legislature showed in 2023," Marty told commissioners, adding, "It's not ambiguous." He said lawmakers could have required a life-cycle analysis had they wanted one.

Biomass and trash incineration supply only about 2 percent of Minnesota's electricity, but environmental groups fear the ruling will lead to more incineration, raising greenhouse gas and particulate pollution. Hudson Kingston, legal director for the group CURE, warned that some of the state's largest coal plants could be converted to partly burn trees. Kingston said such plants should be compared with wind and solar, which emit no greenhouse gases.

Minnesota Power told the commission it is considering converting part of the Boswell coal plant in Cohasset to biomass when the coal facility closes in 2035. The Duluth-based utility already runs a biomass plant in Duluth that produces about 1 percent of its electricity. Spokesperson Amy Rutledge said the plant supports reliability and gives northern Minnesota a safe place to dispose of diseased wood and storm debris. The utility said it looks forward to working with state agencies on a life-cycle analysis.

Community advocates also raised concerns about the Hennepin Energy Recovery Center, a downtown Minneapolis waste incinerator that neighborhood activists have tried for years to shut down. Nazir Khan of the Zero Burn Coalition said, "We don't have any faith." Commissioners Joe Sullivan and Audrey Partridge responded that the Legislature has already determined that electricity from the facility cannot be considered carbon-free, and the commission reaffirmed that part of state law in its decision.

The ruling could face a legal challenge. The Minnesota Center for Environmental Advocacy, which has sued over the issue before, said it is regrouping to decide its next steps.