•Highlights operational challenges for integrating cardboard into fuel systems.
•Highlights operational challenges for integrating cardboard into fuel systems.
•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.
•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.