PFPI-BiomassIsTheNewCoal-April-2-2014

Nitrogen oxides (tons per year)Figure 5 shows that for facilities that go through PSD and a Best Available Control Technologyanalysis, annual NOx emissions tend to increase as boiler size increases, as expected. However, forthe synthetic minor sources that avoid BACT, emission rates are capped around 250 tons or less.Figure 5: Projected emissions of nitrogen oxides700600500No PSDPSD40030020010000 500 1000 1500Boiler capacity (MMBtu/hr)Figure 5. The relationship between permitted NO x emissions for some facilities that went through PSD, versussynthetic minor sources that avoided PSD. Dashed line shows trend for no-PSD facilities; solid line shows trendfor PSD facilities.Although some larger synthetic minor facilities appear to be promising unrealistically low NOxemission rates, the graph makes it clear that allowable NOx emissions from smaller synthetic minorsources tend to be higher than they would be had the facility gone through a BACT analysis todetermine the lowest emission levels that could be achieved.Particulate matter (PM) emissionsAll biomass power plants are large sources of particulate matter emissions; even facilities that havegone through a BACT analysis and have emission rates as low as 0.012 lb/MMBtu emit moreparticulate matter per MWh than a coal plant (Table 2, Figure 2). Because uncontrolled particulatematter emissions from combustion are large, all utility-scale biomass plants use some kind ofparticulate matter control, usually either a fabric filter (“baghouse”) or an electrostatic precipitator(ESP), often in conjunction with a multiclone, which is a series of devices that use centrifugal forceto spin out particles in the larger size classes. 47 Once these controls are in place, they are generallyeffective enough that almost no typically sized biomass plant is in danger of emitting more than 250tons PM per year, meaning that PM is not usually a pollutant that triggers PSD for a new biomasspower plant. 48 However, crucially, this assumption only holds if the plant is running normally47 Only one facility in our database, the Green Energy Partners plant in Lithonia, GA, is proposing to use something other than afabric filter or ESP to control PM emissions, a ceramic filter from the TriMer corporation.48However, for existing facilities undergoing a “major modification,” PSD applicability is triggered when the increase inemissions caused by the modification exceeds certain triggering thresholds. The PSD major significance threshold for PM 2.5 is 1034