Agro-Pellets from Oil Palm Residues/Pine Sawdust Mixtures: Relationships of Their Physical, Mechanical and Energetic Properties, with the Raw Material Chemical Structure

The need for biomass as an alternative source for energy purposes points toward oil palm fruit residues (Elaeis guineensis Jacq.) as an attractive solution. Oil palm industry residue, such as oil palm empty fruit bunch (EFB) composites and mesocarp fiber (PMF), have a high gross calorific value and could help countries meet their energy demands. However, information concerning physical, mechanical, and energy characteristics of agro-pellets made from mixtures of oil palm residue with pine sawdust, is not available. In this research, oil palm residues were mixed at ratios of 100:0, 80:20, 60:40, 40:60, 20:80, and 0:100 with pine sawdust, and were chemically analyzed. Agro-pellets from mixtures were tested on their physical and mechanical properties, and the relationship of these properties with the chemical composition of oil palm residue mixtures was determined. Normality distribution tests of the variables were performed using the Kolmogorov–Smirnov test. Normal variables were analyzed through one-way ANOVA tests. When differences were found, they were validated using the Tukey’s honestly significant difference (HSD) test and were considered statistically significant at p ≤ 0.05. Data not normally distributed were analyzed by the Kruskal–Wallis test. Bulk density, particle density, and gross calorific value of agro-pellets (from mixing 80:20 oil palm residues with pine sawdust) were statistically higher (p < 0.05) to agro-pellets of 100% oil palm residues. Adding pine sawdust to oil palm residues increases some mechanical agro-pellet properties. Addition of pine sawdust to oil palm residues acts to increase some mechanical properties of agro-pellets.