Turning Agroindustrial Waste into Energy: Technoeconomic Insights from the Theoretical Anaerobic Digestion of Apple and Orange Byproducts

Brazil produces large volumes of apple and orange juice, generating apple pomace (AP) and orange waste (OW), which are often underutilized. This study evaluates the potential of these residues for bioenergy production through anaerobic digestion (AD) within a circular economy framework. Three scenarios were analyzed: (I) AD of AP, (II) AD of AP combined with OW, and (III) AD of a centralized system processing 10 times the mass of AP+OW. The combined heat and power (CHP) system recovered electrical and thermal energy, reducing the industry’s energy demand. The estimated energy outputs were 10,815.6 MWh/year for scenario I, 13,436.0 MWh/year for scenario II, and 134,360.4 MWh/year for scenario III. The corresponding net present values were 5.94 million, 7.57 million, and 85.01 million USD, with internal rates of return of 133.33%, 147.01%, and 332.33%, respectively. Scenario III demonstrated the highest profitability due to economies of scale, reducing the capital investment per unit of energy generated. Sensitivity analysis highlighted the strong influence of electricity pricing and capital investment costs on the financial viability. These findings support the integration of AD as a sustainable solution for juice industry waste, promoting renewable energy generation and reducing environmental impacts.