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If you don’t live in Marion County, you may not know that the stack is part of a facility that makes enough electricity to power 8,000 homes. And that electricity is made out of trash.
Inside those industrial buildings, hundreds of tons of stinking garbage burn at extremely high temperatures. Outside, the grazing cows breathe air that smells fresh and grassy.
Oregon’s only trash incinerator, owned and operated by Covanta Energy, opened in 1986. It’s the backbone of Marion County’s waste management system, diverting 90 percent of the county’s trash from landfills and putting it to use creating electricity.
By contrast, less than 10 percent of the garbage from the Portland region is currently converted to electricity.
But that could change.
Metro manages garbage and recycling in the Portland region. After recycling, composting and making a small amount of energy, the region still throws away about a million tons of garbage each year. The majority of it goes to a landfill.
But contracts in place for that arrangement are set to expire in 2019. The Metro Council is considering opportunities to use more garbage as a resource. One possibility could be using some of it to make electricity.
It’s not a new idea. More than 400 garbage incinerators power homes and businesses in Europe, which doesn’t have the space for giant landfills. In the U.S., there are about 75 plants making energy from garbage, including the Hennepin Energy Recovery Center in the trendy North Loop neighborhood of Minneapolis. Hennepin heats the home ballpark for the Minnesota Twins, right next door.
Read about six cities making energy from trash
Garbage + heat = energy for 8,000 homes
At the Covanta plant in Brooks, trucks fully loaded with trash pull up to the scale to be weighed. Then it’s off to the tipping floor where they unload their cargo (or “tip” their trailers) into a 34 foot- deep pit that can hold more than 2,000 tons of waste. That’s enough to fill five Olympic swimming pools.
Inside the plant’s control room, crane operators sit behind glass panels working two six-ton overhead cranes. Each crane has a grapple, a giant version of the claw in those arcade games where players try in vain to grasp plush, colorful toys – except here, every grab is a winner.
“You get really good at it after a while,” says Mike Brazil, who spends about six hours of his 12-hour shift running the crane. His job is to manage the pit. He uses the crane to get a good mix of materials – wet and dry, light and heavy – “so we can get a good burn and the boiler temperature doesn’t go up and down”
At any given time, the plant is producing about thirteen megawatt hours of electricity, which is sold to Portland General Electric. That’s enough to power about 8,000 homes, or a city the size of Woodburn.He lifts huge clawfuls of well-mixed garbage and feeds it into a chute that takes it to the furnace, also known as the combustion chamber. The trash, burning fiercely at temperatures that exceed 1,800 degrees Fahrenheit, heats water in boilers to create steam. This steam then drives a turbine that generates electricity.
Once the garbage is burned for power, it’s time to use what’s left over. Ash and particulates that fly around in the combustion chamber during incineration are eventually collected with fabric filters and combined with the ash that accumulates at the bottom of the chamber. This material is then sorted and used.
First, metals are sorted out. Giant magnets pull out about 7,000 tons of steel and iron each year – that’s almost the weight of all the iron in the Eiffel Tower. In addition, about one ton a day of non-ferrous metals such as tin and copper are removed from the ash. All these metals are recycled.
Facility manager Darby Randklev explains how metal is recycled from the ash.
Until last year, the remaining ash, which occupies considerably less space than the trash it came from – about 10 percent by volume – was sent to a landfill near Woodburn just for ash. But for the last year, the ash has been going to the Coffin Butte Landfill north of Corvallis where it covers new garbage. This “daily cover” prevents trash from blowing and reduces odors.
Emissions monitored, but some are skeptical
Behind the crane operators in Covanta’s central control room is a bewildering display of glowing panels, bristling with dials, knobs and levers. Plant operations, including emissions, are monitored 24 hours a day, every day. Facility manager Darby Randklev explains that since the facility opened in 1986 increasingly stringent standards and better technology have cleaned up emissions considerably.
Randklev, who has worked at the plant for 30 years, helped Marion County start a fluorescent bulb recycling program, which keeps some mercury out of the waste stream. “We all live here,” he says. “We want to do the right thing,”
Mercury in the combustion gases, Randklev explains, is removed with carbon. Acids are neutralized with lime. Fabric filters, similar to vacuum-cleaner bags, capture particulate matter. After the combustion gases are filtered and cleaned they go out through the 258 foot stack.
Eileen Tanner, Covanta Marion environmental/safety specialist, explains how emissions are monitored.
Gary Andes, natural resources specialist at the Oregon Department of Environmental Quality, reviews and inspects the Brooks facility and says it has never been out of compliance with state or federal emissions rules for lead, mercury, dioxins, sulfur dioxide, nitrous oxide and other particulates.
In fact, he says, most of those are “way under, at only about 10 or 20 percent” of the permit limits.
But Dr. Joe Miller of Oregon Physicians for Social Responsibility argues that pollutants are still being emitted. He says that when measured against coal plants on the basis of units of electricity produced, trash incinerators are both dirty and inefficient.
“By burning our trash we would be perpetuating a technology that flies in the face our community’s commitment to a low-carbon future,” he says. He’s referring to the City of Portland’s 2015 Climate Action Plan, which calls for significant reductions in carbon pollution.
Miller also worries about nanoparticles – tiny engineered particles that are in many manufactured goods – that may be in the stack emissions, and the ash used as cover in landfills. “The smaller they are, the more difficult they are to measure or regulate,” he says. “And right now, scientists don’t know what their effects are.”
Jeff Bickford, environmental services division manager at Marion County, says the ash in the Woodburn monofill has been extensively tested. “We did a 10 or 11 year study with the [U.S. Environmental Protection Agency] – testing for the whole gamut – a full chemical breakdown. Dioxin levels were very low.” He adds that there are metals in the ash but they’re bound up in the chemical structure. “They are not mobile.”
The water that percolates through the ash and leaches out some of its components was also tested. “We found the metal levels in the leachate were below the levels in drinking water,” says Bickford.
Health, environment and cost all considerations in the future of garbage
Metro spokesman Ken Ray says that given decisions the Metro Council is poised to make about where garbage in the Portland region goes after 2019, now’s the time to talk about the benefits and trade-offs of technologies that put garbage to use. “Garbage is a resource we are literally throwing away,” Ray says. “Public health, impact on the environment, cost – these are all considerations in making decisions about how to manage garbage in the long term.”
Landfills are likely the least expensive way to dispose of our trash, says Ray. In addition, Oregon law requires consideration of alternatives to disposal in a hierarchy that puts landfills at the bottom of the list.
Ray says if the cost per household were reasonable, “and we’re in discovery mode on that right now,” then using garbage as a resource to create energy should be on the table.
“Burying it in a hole in the ground,” he says, “should be the last resort.”