Long-term emission demonstration using pretreated urban non-woody biomass residues as fuel for small scale boilers

There is currently a lack of non-woody biogenic solid biofuels to replace fossil fuels to expand renewable heat energy due to their combustion-critical behavior (slagging and emissions). For this reason, this study demonstrates a best practice under which non-woody solid biofuels can be put into practice. For this demonstration, a homogeneous non-woody solid biofuel was produced from urban park foliage in accordance with ISO 17225–6:2021 on industrial scale (>50 t). Long-term combustion tests were performed in a small-scale combustion system (80 kW) under field test conditions. Compliance with all emission thresholds of the legal framework was demonstrated (Carbon monoxide (CO): 44.9 mg/m³, Total particulate matter (TPM): 11.9 mg/m³, Nitrogen oxides (NO_x): 279.6 mg/m³, Polychlorinated dibenzodioxins and dibenzofurans + Dioxin-like polychlorinated biphenyls (PCDD/F + dl-PCB): 0.01 ng/m³ and Benzo[a]pyrene (B(a)P): 7.3*10⁻⁶ mg/m³). Additionally, nutrient cycles can be closed by applying the bottom ash as soil fertilizer additive. Based on the study, greenhouse gas-neutral fuels from non-woody biomass residues for comparable applications can be produced based on the demonstration.