A new state law aimed at increasing clean energy in Minnesota also deemed that Hennepin County’s trash burner is no longer a renewable power source, giving new wind to activists’ campaign to shut it down.
Environmental justice advocates argue emissions from the Hennepin County Energy Center, or HERC, are wafting over neighborhoods in north Minneapolis that already face the brunt of the city’s air pollution.
The county is developing a plan to drastically reduce the waste that ends up burned or in landfills. It generally calls for a timeline to retire the HERC based on hitting waste reduction goals. But no specific date is given.
“The fundamental problem is that we are generating too much waste,” said Nazir Khan, an organizer with Minnesota Environmental Justice Table. He said keeping the incinerator running is an easy solution that “disincentives the county from actually addressing the waste problem.”
County officials and staff from Great River Energy, which runs the site, said that the site emits well below what its air permit allows, and that it’s preferable to sending trash to a landfill. Other sources of air pollution, they counter, pose much more of an issue.
Angie Timmons, strategic initiatives manager for environment and energy at Hennepin County, said it’s easy to look at the HERC’s stacks “and say, ‘hey, that’s the problem,’ rather than the cars or the auto shop that’s in your neighborhood, right?”
The purpose of the incinerator is to handle trash, but it does generate some 200,000 megawatt hours of electricity every year, which are purchased at market rate by utility Xcel Energy.
The HERC was removed as a possible source of renewable energy in state law because legislators had concerns about putting it in the same category as solar and wind power. That law also requires Minnesota’s utilities and cooperatives to transition to entirely carbon-free electricity sources by 2040 — which wouldn’t include the incinerator.
Kevin Goss, a spokesman for Xcel, wrote in an email that the utility has an agreement to purchase power from the HERC through 2024. “Beyond that, we are planning on how best to meet the carbon-free and renewable energy standards outlined in the recent 2040 legislation,” he added.
Timmons said the county isn’t required to shutter the HERC by 2040, and added that the law was too new to know yet how it would affect the market for its electricity.
At the plant
The HERC sits in the North Loop neighborhood, where it’s surrounded by pricey condos and Target Field. It’s been burning trash and generating energy since 1989. The plant also creates steam to heat downtown buildings, including the ballpark.
Today, it handles about 45 percent of the county’s trash, with most coming from Minneapolis — about 365,000 tons a year in all, according to David McNary, director of solid waste and energy for the county.
Trash haulers empty loads onto a concrete tipping floor, with a 30-foot-deep pit at the end. Two crane operators pick up the refuse with mechanical claws. The trash is rearranged and “fluffed” before being dropped into hoppers that feed two boilers.
As the garbage burns, steam is captured to turn two electricity-generating turbines. There are several pollution controls on the facility, including baghouses that capture lung-damaging soot, and reactors where a slurry is sprayed to bind with harmful gases. Equipment in the stacks measures pollutants like soot, nitrogen oxides and sulfur dioxide.
In the past five years, the HERC has had one violation of its air permit, according to the Minnesota Pollution Control Agency. In August of 2019, the plant shut down its pollution control system for 11 hours without warning state regulators. Agency spokeswoman Andrea Cournoyer wrote in an email that the HERC completed a corrective plan to avoid a similar situation. No fine was levied.
In the air
Among regulated energy and industrial air polluters in Hennepin County, the HERC ranks high in several categories.
According to 2021 MPCA data, the most recent available, the HERC was the top permitted source of nitrogen oxides in the county, releasing 403 tons; the second-highest source of sulfur dioxide, releasing 17.86 tons; and the sixth-highest for carbon monoxide, releasing 24.4 tons.
These rankings don’t factor tailpipe emissions from cars and trucks, an even larger source of some of these pollutants.
Both nitrogen oxide and sulfur dioxide can irritate those with asthma and lead to the formation of fine soot, while nitrogen oxide is suspected to cause the development of asthma, over long periods, according to the Environmental Protection Agency.
County officials point out that all of these emissions are well under the limits allowed by the HERC’s permit.
But that’s a frustrating argument for Roxxanne O’Brien, because the HERC’s emissions add to what’s already in the air in places like north Minneapolis.
“They want to say ‘this is one thing, we’re under our permit,’ ” said O’Brien, an organizer with Community Members for Environmental Justice. “Yeah, but it’s your thing, plus that thing, plus the freeway.”
Timmons argued that the plant’s emissions are dispersing everywhere, not just into north Minneapolis and areas with environmental justice concerns.
The HERC also released 180,641 tons of carbon emissions in 2021, which warm the planet. That’s about the same effect as driving 35,310 cars for a year, according to the EPA.
Landfill vs. incineration
State law also prefers incineration over landfills, as does the EPA’s suggested formula for how to handle waste streams — though the agency is reviewing whether to change that, according to an October report from trade publication Waste Dive.
Modern landfills are lined, but there’s still a risk contaminants could reach nearby groundwater. They also produce methane gas from decomposing garbage, a potent greenhouse gas that is many times worse for global warming than carbon dioxide if it is not captured correctly, according to EPA.
Incinerators still send ash to landfills. By weight, 25 percent of the trash that goes into the HERC comes out as ash and is sent to a specialized landfill in Rosemount, McNary said.
Local activists and Hennepin County do agree on one thing: Less waste overall needs to be sent to disposal.
The county has a goal of diverting 90 percent of the waste it receives from disposal, and released a draft plan to achieve those goals on Feb. 22.
Officials also face a deadline in state law for metro-area counties: 75 percent of trash has to be diverted to recycling, composting or other methods by 2030. Right now, Hennepin County is diverting 39 percent.