The Physiochemical Properties of Pellets Made from the Foliage of Vegetable Crops

The increasing demand for renewable energy has driven interest in utilizing agricultural residues for bioenergy applications. This study investigates the pelletization of foliage from six vegetable crops, including tomato, eggplant, summer squash, cucumber corn, and soybean, to assess their potential as bioenergy feedstocks. The physiochemical properties of these biomasses, including particle size and shape, lignin, and elemental composition, were analyzed to determine their impact on pellet density and durability. The results reveal significant variations in pellet quality across different biomasses. Cucumber and summer squash demonstrated the highest pellet densities (1.48–1.51 g/cm 3 ) and superior durability (98.1% and 94.2%, respectively), making them the most promising candidates for pelletization. In contrast, eggplant exhibited the lowest density (1.14 g/cm 3 ) and durability (47.2%), indicating poor pellet quality. The correlation between pellet durability and pellet density was positive and modest at r = 0.647 . The study further highlights the impact of inorganic elements on pellet properties, where the high silica and chlorine content of cucumber, summer squash, tomato, and eggplant reduced energy efficiency and increased ash-related challenges. The resulting color parameters analysis (L*, a*, and b*) shows that the pellets from eggplant, tomato, summer squash, and cucumber foliage are darker than pellets from sawdust, corn stover, and soybean residues.