Planning for increased bioenergy use—Evaluating the impact on local air quality

The Swedish energy system is undergoing a transformation due to threats about climate change and political decisions to reduce green house gases and to phase out the nuclear power. The goal is to convert the energy system from a system based on fossil fuels and nuclear power to one based on renewable energy sources. Bioenergy is an available domestic, renewable, carbon dioxide neutral energy source and therefore an increase of the use is forecasted in the future. Studies have shown that bioenergy may cause negative impacts on human health and on the environment due to emissions to air. The aim of this study was to investigate how a future conversion to bioenergy-based heating affect the air quality in residential areas. The contribution of particulate matter (PM10) and benzene from existing heating systems as well as from conversion from electrical heating and firewood boilers to pellets and small-scale district heating systems was investigated. The investigations included monitoring of energy need for heating, identifying suitable energy systems for conversion, identifying emission factors, dispersion calculations and application of the results in a geographical information system (GIS). The results show that conversion from electrical heating to pellets in the investigated areas does not affect the air quality. The GIS maps showed the expected concentrations caused by small-scale combustion of bioenergy-based fuels clearly. The dispersion pattern of the emitted gases and particulates was visualized and the maps can be used for planning purposes when dealing with new residential areas.