From Garbage to Electricity? Portland Metro Explores Options
|COURTESY OF COVANTA - The Covanta facility in Marion County is the only combustion facility of its type in Oregon. Turning garbage into electricity through combustion is one of Metro's three options in its Solid Waste Roadmap.|
In deciding the fate of the region’s garbage, the Metro Council has narrowed its half-dozen options down to three.
The use of dry anaerobic digestion, refuse-derived fuels and gasification are no longer on the table, councilors and staff decided at an hour-long July 28 work session.
Instead, Metro will pursue a combination of three other options: the continued use of landfills for some of the region’s waste; traditional waste-to-energy, also known as combustion; and Advanced Materials Recovery facilities, to better capture recyclable materials from the wet and dry waste streams so the rest can be more valuable to other processes.
The most controversial of those will be combustion, which involves the complete oxidation of a fuel under controlled conditions.
The heat generated from the process is recovered in a boiler to generate steam, which can be used directly for heating or industrial purposes, or passed through a steam turbine-generator to create electricity.
Four out of 19 companies that responded to Metro’s Request for Expressions of Interest this spring are direct combustion facilities.
One of them is New Jersey-based Covanta, which has a facility in Brooks, north of Salem, that processes about 200,000 tons of that region’s garbage each year and generates up to 13 megawatts of renewable energy, which is sold to Portland General Electric.
After the combustion process, the resulting ash — about 10 percent of the volume of incoming garbage — is sent to a site near Woodburn, where crews further extract the metals present.
The rest of the ash is used in place of dirt to cover the garbage buried at the Coffin Butte Landfill, north of Corvallis.
Covanta operates or owns 40 energy-from-waste facilities in North America, Italy and China.
The Marion County Covanta facility — the only one of its kind in Oregon — operates under a permit issued by the Oregon Department of Environmental Quality, which was last issued in 2012 and is up for re-issue in 2017.
DEQ does annual reviews to ensure it meets federal emissions and pollution control limits under the Clean Air Act of 1990, as well as limits established by the state and DEQ.
Emissions of lead, mercury, dioxins, sulfur dioxide, nitrous oxide and other particulates are evaluated.
Less waste to landfill
The garbage option discussion comes after a year of Metro’s “Let’s Talk Trash” events around town, held to educate the public and get input on options.
Metro’s contracts with Waste Management expire at the end of 2019. The agency’s goal has been to send less of the region’s waste to the landfill; currently about 1 million tons of waste is primarily sent to the Columbia Ridge Landfill, in Arlington.
Even with other options in play, the region will still use the landfill for about 80 percent of its waste, spokesman Ken Ray says.
“To set up a new facility (to take all of the region’s waste) would take significant capital investment,” he says. “The landfill is still part of the picture. We want to send out less waste to begin with.”
Parallel discussions are underway to figure out how to recover more food scraps, to make the dry waste stream more valuable.
Meanwhile, the council also will look at policies and incentives to establish local Advanced Materials Recovery facilities, which would focus on getting more materials out of the waste, using more labor- and mechanically intensive processes than Metro currently has at its transfer stations.
“If we’re able to implement them, we’ll be able to reduce what goes to the landfill,” he says. “We’ll look at how to set up a policy framework that encourages more of those facilities in the region.”
Meanwhile, the council pitched its other three options — anaerobic digestion, gasification and refuse-derived fuels — for the time being.
“The way our waste stream is managed now, it doesn’t lend itself to those facilities in the short-term,” Ray says. “Some of those facilities require advanced material recovery to get stuff out of the waste stream for more pure feedstock. We weren’t quite ready for that.”
Toward the end of the hour-long work session, Metro President Tom Hughes helped put the issue in perspective for his colleagues.
“We don’t need to decide now what our complete recovery will be,” he said. “We need to find compromise between what’s physically possible, what’s technologically possible and what’s economically possible.”
Part of a Metro councilor’s job, he said, is “to convey the political message and gather the political information on what is tolerable to our constituents.”
If the council moves forward with combustion, he says, “there is a lift if we have to ask people for more money to deal with their garbage. ... There is an even greater lift if public perception has not kept up with the technologies.”
The burning processes used by facilities such as Covanta, Metro Councilor Bob Stacey said, “are virtually as clean as you could ever get them. There’s nothing that even approaches the limit of the DEQ.”
And yet, he says, “public perception is that burning is not a good thing to do.”
The next public meeting is set for Nov. 17. Whatever decision is made then, Stacey said, “We need to own our decision at the end of the day and be willing to step up and make those kinds of efforts to go forward.”
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