Investigation of using eggshell and calcium carbonate to improve biomass pellet energy efficiency

Fossil fuel depletion and environmental concerns necessitate sustainable energy alternatives. Biomass, being abundant and carbon neutral, is a promising option. This study compares the effects of calcium carbonate (CaCO₃) and eggshell additions to biomass under identical pyrolysis and combustion conditions. Rice chaff and corncob were mixed with 2, 5, and 10% CaCO₃ or eggshells and pyrolyzed at 300 °C and 500 °C. Thermogravimetric analysis showed improved thermal stability, especially at higher mixing ratios. Elemental and proximate analyses revealed reduced carbon, hydrogen, and oxygen with increased ash, while FT-IR confirmed structural changes. A 2% mixing ratio best preserved combustion indices. Corncob-based samples at 300 °C exhibited excellent performance, with a calorific value of 28.20 MJ/kg and 66.58% energy yield. The findings indicate that eggshells, an accessible biowaste, perform comparably to commercial CaCO₃ in enhancing fuel properties. Their cost-free and eco-friendly nature makes them a viable biomass additive. Further research should explore industrial-scale applications and other calcium-based biowaste materials for optimisation.