Optimization of biomass briquette production: influence of time and pressure on compaction, dimensional stability, and sustainable energy potential

Abstract

Fossil fuels, although dominant in the energy matrix, cause significant environmental impacts. As a sustainable alternative, this study evaluated the production of briquettes from sugarcane bagasse, aiming to optimize its yield by analyzing the effects of pressure and pressing time on longitudinal expansion (height and diameter). The material, collected at the Farmers' Market in Castanhal-PA, was processed (crushed, dried, ground) and pressed in a hydraulic press, with expansion measurements at intervals of 1 to 48 hours. A Central Composite Rotational Design (CCRD) with 4 factorial points, 4 axial and 3 central, was used. Next, moisture content was determined by infrared; ash content in a muffle furnace at 525 °C for 4 hours; volatile matter at 950 °C in a muffle furnace; and fixed carbon by the difference between the percentages of moisture, ash and volatile matter. As a result, the height of the briquettes showed an explainability of 91.12%, being positively influenced by time (5.50 min) and pressure (21.24 tf), with local maxima indicated by negative quadratic terms, suggesting optimum at intermediate levels. The diameter had lower explainability (40.49%), being more sensitive to time (0.405) than to pressure (0.013), with a negative interaction (-0.063) showing that simultaneous increase is not advantageous. Quadratic effects confirm local maxima, indicating that extreme times and pressures reduce compaction. Thus, moderate conditions promote structural stability and greater energy efficiency of the briquettes. The results demonstrate that the briquettes produced are technically viable to replace fossil or wood fuels in industrial processes, combining energy efficiency with environmental benefits.