County wants to burn more garbage at Minneapolis incinerator

HERC stacks
The HERC stacks are 215 feet tall. MPCA models show pollution disperses mostly to the north and south of the plant, with heaviest deposition between Broadway Street and Loring Park.
MPR Photo/Stephanie Hemphill

Hennepin County wants to burn more garbage at its downtown Minneapolis waste-to-energy plant, but the plan is running into opposition. Some neighbors are worried about whether pollution from the plant is bad for their health. Others say burning waste -- even to produce electricity -- is not the best thing to do with it.

The Hennepin County waste-to-energy plant sits just to the northwest of its new neighbor, the under-construction Twins ballpark. For twenty years, it's been burning 1,000 tons of garbage a day, and producing electricity for Xcel Energy. Last winter it also started supplying steam heat to downtown buildings.

At the heart of the plant is a canyon of trash. Garbage trucks dump their loads here, and a bobcat pushes the trash off the edge of a 40-foot cliff. From a glassed-in perch, ten stories up, Bob Hammer operates a giant claw that "fluffs" the trash -- he mixes it to combine wet and dry material -- and then he lifts a ton of it at a time up to the hoppers that feed the furnaces.

"Those hoppers are gravity fed; the trash, by its own weight, is fed down into the hoppers, down into the furnaces," Hammer explained. "You can get anything from parts of dead animals to your regular kitchen garbage, to stoves, refrigerators, you name it, could get accidentally pushed in."

The air is dusty, and there's a slight smell of garbage. Two giant metal ducts carry the air to the furnace. That creates negative pressure on the tipping floor, so the smell of garbage doesn't escape the building.

Two-thirds of the waste is paper, cardboard and other conveniently combustible material. Burning it produces enough electricity to power about 25,000 homes.

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Hennepin County wants to produce more electricity, by burning 10 to 20 percent more trash here, but state law limits how much the plant can burn; it needs City Council approval to burn more.

Waste-to-energy plant
The waste-to-energy plant handles about 1,000 tons of waste a day. That's a little more than one-third of the trash generated in Hennepin County. There's another garbage burner in Elk River, and the rest of the trash is landfilled.
MPR Photo/Stephanie Hemphill

The county says additional emissions from the plant would be negligible. The Minnesota Pollution Control Agency says the plant has only exceeded its permit limits twice.

For a day or so in 1999, the plant put out almost nine times its limit for hydrogen chloride, a corrosive gas. There was an equipment malfunction, which was corrected quickly.

And in the early days, too much mercury was escaping. MPCA engineer Anne Jackson said the agency required the plant to use activated carbon to capture mercury.

"Once that was in, they've always been able to easily able to meet, and be far lower than the applicable mercury emissions limits," Jackson said.

The plant emits 500 tons a year of nitrogen oxides, or NOX. These are precursors to smog, which is harmful to children, the elderly, and people with lung and heart conditions. But Jackson says it's a drop in the bucket compared to other sources: most of the NOX in Minnesota comes from cars and trucks. If the plant gets permission to burn ten-to-twenty percent more trash, its NOX emissions would still squeak by, just under its permit levels.

Some neighbors say any amount of mercury -- or any other pollutant -- is too much, given the air quality problems in Minneapolis. The federal government recently said there's enough pollution in Hennepin and Ramsey counties to cause 50 preventable deaths.

HERC control room
In the Hennepin Energy Recovery Center (HERC) control room, technicians monitor plant operations, including pollution controls. The MPCA says the plant has only exceeded its limits twice.
MPR Photo/Stephanie Hemphill

Another issue is whether burning it to make electricity is the highest and best use of the trash. Half of the material that comes to the burner is either recyclable or compostable.

State Rep. Frank Hornstein, DFL-Minneapolis, said Hennepin County isn't doing enough to encourage recycling and composting. Hornstein said the burner provides the county a perverse incentive to downplay recycling.

"They need to feed the beast as it were, so there's very little incentive for the county, once that incinerator's up, to be very, very aggressive on recycling which they need to be," Hornstein said. "And I think that's why Minnesota is behind other states, frankly."

Minnesota has an official waste hierarchy. Like the food pyramid, it sets priorities. It says the best ways of handling waste are to reduce, re-use, and recycle. Then comes waste-to-energy, and at the bottom is land filling. Advocates say we'd save money and reduce greenhouse gases by recycling and composting more.

The Minnesota Climate Change Advisory Group recommended increased recycling and composting as a way to cut down on greenhouse gases and save money.

HERC burner
The temperature in the burner reaches 2000 degrees Fahrenheit. HERC officials say burning garbage instead of coal to produce electricity helps reduce global warming, because the trash is part of the short-term carbon cycle. But critics say even fewer greenhouse gases are produced by recycling and composting.
MPR Photo/Stephanie Hemphill

The Minneapolis City Council's zoning and planning committee will take up the question of the garbage burner on Thursday next week.