Technical Bulletin No. 0998: Methane and Nitrous Oxide Emissions from Biomass-Fired Boilers and Recovery Furnaces

NCASI conducted a study to quantify methane (CH4) and nitrous oxide (N2O) emissions from biomass-fired boilers and kraft recovery furnaces in order to develop emission factors for potential use in greenhouse gas (GHG) inventories. As part of this study, CH4 and N2O emissions from five biomass-fired boilers, five direct contact evaporator (DCE) recovery furnaces, and three non-direct contact evaporator (NDCE) recovery furnaces were measured using extractive Fourier Transform Infrared (FTIR) spectroscopy. Data on CH4 emissions from 22 biomass-fired boilers, provided in the 2009 Boiler MACT/CISWI test reports, were also included in this study. For biomass boilers, average CH4 and N2O emissions were 0.0049 kg/MMBtu and 0.0019 kg/MMBtu, respectively. For DCE recovery furnaces, average CH4 and N2O emissions were 0.0024 kg/MMBtu and 0.00036 kg/MMBtu, respectively. In the case of NDCE recovery furnaces, average CH4 and N2O emissions were 0.0014 kg/MMBtu and 0.00044 kg/MMBtu, respectively. Average emissions of CH4 and N2O were found to be lower than the default emission factors provided by EPA in the Federal Register for use in GHG reporting calculations (solid biomass fuels: 0.032 kg CH4/MMBtu and 0.0042 kg N2O/MMBtu in Table C-2; softwood kraft pulping liquor: 0.030 kg CH4/MMBtu and 0.005 kg N2O/MMBtu in Table AA-1).