Effect of fuel quality classes on the emissions of a residential wood pellet stove

In order to evaluate the influence of pellet quality classes, as defined by the ISO 17225-2, particulate matter and gaseous pollutants were characterized for different class fueled pellets in the emissions of a stove at partial and nominal load. Total suspended particulate (TSP) was sampled with a dilution system, then characterized for total carbon (TC), inorganic carbon (IC), water soluble organic carbon (WSOC) polycyclic aromatic hydrocarbons (PAHs) and the main soluble ions. Gas monitoring shows that CO and NO emission factors are higher for lower quality pellet. Low quality pellet emission factors are also higher for TSP and soluble ions, thus the pollutants linked to pellet ash content. On the other hand, carbonaceous component emission factors are higher for higher quality pellet; nevertheless, at nominal load, lower quality pellet emits more toxic PAHs. The higher stove power restricts instead the emissions of incomplete combustion products: CO, TSP and carbonaceous components. Principal Component Analysis (PCA) allows to have a complete overview of the obtained results: the effect of operating phase on emission factors is less strong then pellet quality, even if the pollutants produced by low heat power are more hazardous than the ones connected with pellet quality. In conclusion, the study provides not only quantitative information on the influence of pellet quality classes on stove emissions, but also their chemical fingerprint. Moreover, it indicates that the amount of hazardous emissions is also linked to stove power.