Emission factors and emissions from residential biomass combustion in Sweden

Small scale biomass combustion can be a major source of air pollutants like emissions of greenhouse gases, acidifying pollutants, NMVOC, particulate matter, heavy metals, PAH and dioxins.

On a yearly basis Sweden is obliged to report air emissions of these pollutants to different international bodies. Until submission 2005, covering data for 1990-2003, only one emission factor for each pollutant was used for the reporting of emissions from residential biomass combustion. The results from a closer examination by Statistics Sweden of existing national energy statistics for residential heating has enabled a disaggregation of the fuel consumption of biomass by fuel type (wood logs, pellets, wood chips), as well as by technology (boiler, stoves, and open firing places). This study aimed at improving the reporting of emissions from small- scale combustion of biomass by revising the emission factors for N2O, NOX, CO, NMVOC, SOX, NH3, total suspended particles (TSP, PM10, PM2.5, metals, dioxins and PAH. Furthermore, the time series 1990-2004 for these emissions were updated.

In this work the revised emissions factors were to a large extent based on results from the Swedish Energy Agency research program “Biofuel, Health and Environment”. In addition a literature review was carried out to collect data from other Swedish studies as well as relevant international studies.

Results from several recent measurement studies, together with dissaggregation of emissions factors by technology and fuel type, lead to quite large differences between previously used emission factors and the revised emission factors presented. In particular the new emission factors for NMVOC and particles are much lower, whereas the new emission factors for CO and dioxin are higher.