Statistical Evaluation of Biomass Composition Influencing Pyrolysis Product Distribution of Agricultural Residues

Abstract

The conversion of agricultural biomass into energy offers a sustainable pathway for mitigating greenhouse gas emissions and promoting circular economy. This study investigates the energy potential of various biomass materials, such as pine needles (PN), rice straw (RS), lentil straw (LS), bamboo leaves (BL) and mustard straw (MS). Proximate, elemental, FTIR (Fourier Transform Infrared Spectroscopy) and TGA (Thermogravimetric Analysis) were conducted to determine the chemical composition and thermal behavior of the selected biomass materials. Dulong’s formula, the Modified Dulong’s formula, and Vandralek’s equation were used to assess the biomass energy content. Pine needles and lentil straw exhibited high volatile matter content (89.9% and 90.8%), low ash content (0.16% and 0.18%), and higher carbon content (45.75% and 40.55%), all of which are beneficial for bio-oil yield. The highest bio-oil yield (25.25%) was obtained from pine needles followed by lentil straw (24.12%) in pyrolysis experiments at 500°C. On the other hand, rice straw has the highest biochar yield (39.67%) and Brassica straw has the highest gas escape (33.46%). These variations in product yields highlight the diverse chemical compositions and pyrolysis behaviours of various biomass residues. The ratios of H/C, O/C, N/C and S/C provide further insights into the chemical characteristics and potential reactivity of the biomass. Pine needle showed higher HCV (Higher Calorific Value) value of 21.01, 14.99 and 18.58 using Dulong, Modified Dulong and Vandralek formula, respectively. Among the predictive models, Dulong’s equation showed the closest overall agreement with the reported experimental HCV values, with relative errors ranging from −7.91% to +16.23%. The Modified Dulong equation generally underestimated the HCVs, with relative errors ranging from −17.41% to −83.87%, while the Vandralek equation showed greater deviations, ranging from −36.40% to +5.27%. This study highlights biomass as a viable alternative to conventional energy sources and suggests paths for future research while highlighting environmental benefits.