CO, NO_x, PCDD/F, and Total Particulate Matter Emissions from Two Small Scale Combustion Appliances Using Agricultural Biomass Type Test Fuels

In Germany, solid biomass fuels based on agricultural byproducts are only used in marginal amounts for small scale combustion. This is the consequence of several regulatory constraints, in particular requirements defined in the first ordinance of the German emission control act (1. BImSchV) including the mandatory utilization of dedicated licensed boilers for such fuels. For the licensing, test fuels with defined fuel composition representing straw and cereal grain like fuels are demanded, and strict emission thresholds have to be met both during type testing and during periodic chimney sweep measurements. To facilitate the market introduction of the first licensed boiler, agricultural biomass test fuels with characteristics being representative for the composition of these assortments were produced and utilized for combustion tests. Emission measurements (i.e., for CO, NO_x, PCDD/F, and total particulate matter) were performed by an accredited institute according to the relevant methods. It was demonstrated that test fuels with dedicated fuel composition can be produced on the bench scale. The results prove that compliance with the strict emission thresholds of 1. BImSchV in Germany can be realized even with challenging fuels if an appropriate boiler is combined with an efficient dust separator. Accordingly, PCDD/F emission levels and toxicity almost as low as for wood combustion were observed.