Valorization of Garden Biomass and Plastic Waste into High-Calorific Biochar for Energy Co-Firing

This study examines the technical feasibility of co-processing garden waste with polyethylene (PE) waste in order to generate high-calorific biochar through slow pyrolysis at 500 °C for a duration of 60 minutes. Calorific value (CV) research revealed that the GW:PE biochar mix attained a maximum CV of 24.14 MJ/kg, with a fixed carbon content of 70.98% and a minimal ash level of 12.4%. These findings demonstrate a significant improvement in energy density and combustion properties relative to raw biomass. The energy performance of GW:PE biochar was benchmarked against Melawan sub-bituminous coal, demonstrating equivalent fuel quality and underscoring its appropriateness for co-firing applications. Proximate and final investigations confirmed the synergistic role of PE in improving biochar quality while preserving advantageous combustion characteristics. The results highlight co-pyrolysis as a viable method for waste valorization and sustainable bioenergy generation. This technique converts various waste streams into energy-dense solid fuels, adhering to circular economy principles and offering a viable alternative to fossil fuel reliance.