Integrated Experimental and Aspen Plus Simulation of Bioethanol Production from Sugarcane Residues: Experimental Optimization, Fermentation—Purification Simulation, and Techno-Economic Evaluation

The increasing demand for sustainable energy and the need to reduce greenhouse gas emissions have strengthened interest in bioethanol as a renewable fuel. This study combined laboratory experimentation with process simulation to improve bioethanol production from sugarcane residues, specifically molasses and bagasse. Experimental work evaluated the effects of molasses dilution, yeast loading, sulfuric acid concentration, and cellulase dosage on ethanol yield. The highest molasses-based yield, (553.5 g/L ± 25.67), was obtained at a dilution ratio of 1:1 with 5 g yeast loading, reflecting an effective balance between substrate availability and microbial activity. For bagasse, dilute-acid hydrolysis using 10% H2SO4 and 7 g yeast produced (127 ± 6.21 g/L) ethanol. Higher acid concentrations and excessive enzyme addition reduced production because of inhibitor formation and declining hydrolysis efficiency. The optimized conditions were subsequently applied in Aspen Plus V.11 to simulate fermentation, separation, and purification. The Aspen Plus model was developed to simulate the fermentation, gas–liquid separation, and ethanol purification stages using experimentally determined conditions, while the pretreatment and acidic/enzymatic hydrolysis stages were not explicitly modeled. The model predicted 477 kg bioethanol per 1000 kg bagasse at scale. Economic assessment estimated a total installed cost of USD 1.7 million and an annual net profit of USD 141,064, indicating technical and economic feasibility. Overall, the integrated approach supports scalable bioethanol production and effective agricultural-waste valorization.