The Missoula City-County Health Department made a preliminary determination on Thursday to grant the University of Montana an air quality permit to build a $16 million biomass gasification boiler on campus.
It's a major step for UM as it seeks to reduce its carbon footprint by replacing 70 percent of its natural gas consumption, which is now used to heat campus, with wood, a renewable resource.
The state-of-the-art biomass gasification system would emit more pollutants than UM's existing natural gas boilers. At the same rate, what UM is proposing would be the cleanest wood-fired boiler in the state.
Health officials are somewhat limited in their ability to deny air quality permits. If applicants meet federal, state and county standards for clean air and emissions, then the department must grant a permit. The process has been described in some circles as a checklist - albeit a very extensive and somewhat complex one.
The controversial project has caught the attention of city and county elected officials in recent weeks, with UM's proposed boiler appearing as an item on the agendas of both the Missoula County commissioners and the City Council's Conservation Committee.
The health department will accept public comment on the draft permit for the next 15 days.
Jim Carlson, the department's environmental health director, said the permit holds UM accountable to the emission levels the manufacturer, Canadian-based Nexterra Systems Corp., assures are possible.
"We're holding them to the information they provided to us," Carlson said. "They have to meet the limits they say they can meet."
Those levels are below the minimums required by law.
Part of the health department's responsibility is to ensure the university is using the best available control technology. In this case, UM is proposing two devices to control particulate matter and oxides of nitrogen emissions, technology that is above and beyond what is required, Carlson said.
"We don't know any control measure that's better," said Ben Schmidt, a department air quality specialist.
The boiler at Pyramid Mountain Lumber in Seeley Lake burns wood waste, but is comparable in size with what UM is proposing. The lumber mill emits five times more particulate matter than what's proposed for UM's biomass boiler, Carlson said.
The last year the hog fuel boiler at Smurfit-Stone Container Corp. was in full operation was 2009; it released 97 tons of particulate matter. UM's boiler is projected to release a maximum 5.2 tons of particulate matter a year, according to documents provided by the health department.
Schools in Dillon and Darby have smaller biomass boilers, but both emit more pollutants than what UM proposes.
The health department received eight letters of public feedback prior to its preliminary decision, many of them signed by more than one person. Their concerns touched on everything from emissions to the economic feasibility and vitality of the project. The latter was beyond the scope of the permitting process.
The winter months in the Missoula Valley are of particular concern to those who lived here when the air was less ideal to breathe.
UM's proposed wood gasification boiler is the equivalent of 560 pellet stoves or roughly 127 woodstoves, say health department officials. Still, that will represent less than 1 percent of the particulate matter released into the Missoula Valley airshed each winter. Woodstoves, on the other hand, account for 55 percent of small particulate matter in Missoula's winter airshed.
Still, wood burns dirtier than natural gas.
The woody biomass boiler would emit three times more particulate matter than UM's existing natural gas boilers and oxides of natural gas would nearly double.
Missoula County has been close in recent years to surpassing federal air-pollution limits, so any additional pollutants are a concern, Carlson said.
At the same time, UM has kept its promise to use the best available technology for burning wood, he added.
Once the biomass boiler goes into operation, the university will be required to perform a stack test within 180 days to ensure compliance with the air quality permit.