Evaluation of the properties of cardboard for power generation

This study presents the first comprehensive characterisation of post-consumer cardboard as a biomass fuel for power generation, with emphasis on its suitability for pulverised fuel and stoker furnace systems. Compared to eucalyptus, cardboard samples exhibited lower carbon content (38.2–39.3 % vs. 46.7 %), reduced higher heating values (15.9–16.5 MJ/kg vs. 21.0 MJ/kg), and significantly higher ash contents (8.9–10.6 % vs. 0.6 %). A novel thermogravimetric method was developed to quantify calcium carbonate content, revealing concentrations of 5.5 % in unprinted cardboard and up to 12.2 % in printed paperboard. Despite its lower energy density, cardboard chars exhibited favourable combustion characteristics, including a higher proportion of thin-walled and porous char morphologies, which are known to burn quickly. The study also investigated the impact of combustion on particle shape, identifying a potential correlation between sphericity and aspect ratio. This correlation, if validated, could simplify the estimation of three-dimensional sphericity for combustion modelling. Operational challenges were also identified, including the formation of low-density agglomerates during milling and elevated ash content, which may affect fuel handling and system compatibility. Overall, the findings support the integration of cardboard into the biomass fuel mix, contributing to fuel diversification and energy resilience in the transition to low-carbon power systems. Further research on ash fusion behaviour, emissions profiling, and large-scale combustion trials is recommended to confirm its industrial applicability. • First full characterisation of post-consumer cardboard as fuel for PF combustion. • Developed a novel TGA method to quantify calcium carbonate in cardboard. • Cardboard chars show fast-burning porous morphologies despite low energy density. • Identified a potential link between particle sphericity and aspect ratio. • Highlights operational challenges for integrating cardboard into fuel systems.