Emissions of particles and organic compounds from small and medium scaled biomass combustion

The use of biomass for domestic heating is common in some parts of the world. Biomass is a Renewable Energy Source (RES) and it is considered as a climate friendly fuel since it is a CO 2 neutral energy source. However, combustion of wood biomass in the residential sector is a main contributor to pollution of the ambient air, mainly in terms of fine particles. This is a severe health problem and needs to be addressed to improve the air quality. There is also a gap between calculated air quality particle concentrations using the available emission data, measured at the stack, that needs to be addressed. The concentrations of organic particles in the atmosphere are higher than expected from reported emission factors, but there is also a gap between emission factors registered in different countries, emphasising the need of similar standards for individual countries, or at least more information around the emission data. The residential combustion of wood biomasses is characterized by incomplete processes leading to high concentrations of gases and particles containing both organic and inorganic substances. The formation of organic particles is a temperature dependent process where Semi Volatile Organic Compounds (SVOC) condense on solid particles or form particles after nucleation. Thus, the temperature where particle emissions are measured is crucial to the result. There are many different standard methods for the measurement of combustion generated particle emission, some differ between different combustion sources. Most standards focus on the most straight forward measurement methods, collecting particles directly from the hot fumes, while in other standards the particles collection is after a dilution of the exhaust gases, taking into account the condensation of organic gases. In particularly for residential biomass heating appliances there is no European harmonized standard for measuring particles and a few Member States provided with own method (to be performed during laboratory type testing). The methods are different each other: one method is adapted from the standard used to measure particles produced by big plant fed with fossil fuels (just collecting solid particles at high temperatures), the other method is based on the dilution of sampled gases to collect solid and condensed particles. The aim of the present work is to provide background information both on different emission standards used in combustion appliances and on the development of the particles from the combustion zone to the ambient air at a larger distance from the source. The development of the particles change the amount of particles originating form biomass combustion by both number and mass. Input data for this study is taken from the literature and from a survey sent to laboratories engaged in emission measurement from small to medium scaled biomass combustion facilities