Workshop rationale and aim
Most recently, fine particulate pollution gave rise to debate in numerous European countries as concentration limits were overstepped more frequently and more clearly than in the past. Urban areas were especially affected. Industry, traffic, agriculture and residential heating proof mainly responsible for high fine particulate emission levels. In Austria for instance, within the residential heating sector small-scale biomass combustion plants are responsible for about 88% of the PM10 emissions, most of them (about 86%) are poorly controlled old biomass combustion systems.
Compared to oil or natural gas, biomass contains a considerable amount of ash. This inevitably leads to fly ash emissions during combustion. In medium and large-scale biomass combustion systems fly ash emissions are typically efficiently precipitated by appropriate filters (ESP or baghouse filters). Small-scale (residential) biomass combustion plants however, are not equipped with filters due to economic reasons and the immature status of the technology. Fly ash emissions of complete biomass combustion, which is usually achieved by modern and automatically controlled small-scale biomass combustion plants, consist mainly of inorganic aerosols and are related to the PM1 fraction (particulate matter with a particle size smaller 1.0 µm). Carbonaceous aerosols are a product of incomplete combustion, which is often the case in poorly controlled old biomass combustion systems or natural draught systems (like chimney stoves or tiled stoves), and consist of elementary carbon (soot) or condensed hydrocarbon compounds (organic aerosols). Moreover, old residential heating systems emit considerably higher PM1 emissions than modern small-scale biomass combustion systems. The formation of carbonaceous aerosols can be notably reduced by technical measures concerning combustion and process control technology (primary measures). The formation of inorganic aerosols however cannot be significantly prevented in the same way but needs new “Low-Dust combustion” technologies or requires secondary measures such as dust precipitators.
Fine particulate matter is the thoracic fraction out of total particulate matter, i.e. the fraction that can pass the larynx and reach the lung. There is strong epidemiologic indication that particulate matter in air has serious adverse health effects, but there are also indications that there exist considerable differences regarding the toxicological effects between inorganic aerosols and carbonaceous aerosols, which is of great relevance for the environmental evaluation of different small-scale biomass combustion technologies.
The workshop accommodated the aforementioned issues by its three key topics "Low-Dust combustion technologies", "Small-scale precipitators" and "Health effects" and thus gave a comprehensive overview of ongoing developments and recent findings.The event took place as a parallel session within the 3rd Central European Biomass Conference 2011 in Graz, Austria.
Organised in cooperation with :