Quality Assessment of Wood Pellets for Residential Heating Systems and Combustion Behavior in a Pellet Stove

The use of wood pellets is steadily increasing in the European Union. The majority of wood pellets on the German market carry the label ENplus indicating a consistent fuel quality. In order to prove this assumption 42 different pellet samples in bags were collected and extensively analyzed. This included combustion properties, physical properties as well as their chemical composition. Eight of the 42 samples did not fulfil the requirements for the standard DIN EN ISO 17225-2. But overall a positive result for wood pellets quality on the German and European market was confirmed. Interestingly, large differences in potassium content (between 280 and 900 mg/kg) which can influence the amount of particle emission were observed. During the combustion of 12 selected pellet samples, no clear dependency between flue gas emission and ash content, potassium content, bulk density or pellet length were found. Therefore, the selection of the fuel can lead to big uncertainties during the combustion in pellet stoves. This has to be further investigated in order to maybe fine the yet unknown pellet parameter influencing the emission behavior in a pellet stove.
Proceedings of the 27th European Biomass Conference and Exhibition, 27-30 May 2019, Lisbon, Portugal, pp. 667-672