Estudo de viabilidade técnica e econômica de uma planta de biometano: avaliação da inclusão do melaço na codigestão de resíduos sucroalcooleiros

Abstract

Biogas production from sugar-energy residues, such as vinasse and filter cake, stands as a strategic alternative for diversifying the energy matrix and mitigating greenhouse gas emissions. In this context, this work aimed to evaluate the technical and economic feasibility of a biomethane production plant integrated into a sugar and ethanol mill, analyzing the impact of including molasses in anaerobic co-digestion. The methodology was based on process simulation and financial modeling across three phases of implementation: Phase 1 (Filter cake), Phase 2 (Inclusion of straw), and Phase 3 (Inclusion of molasses). Mass and energy balances, as well as biodigester sizing, were performed considering industrial operating parameters and real data from a partner company. The results showed that the inclusion of straw (Phase 2), although technically feasible, reduced the Internal Rate of Return (IRR) to 17.1% due to high capital investment in reactor volume and the opportunity cost of biomass. Conversely, the addition of molasses in Phase 3 proved decisive for maximizing profitability, increasing the IRR to 19.1% and the Net Present Value (NPV) to R$80.9 million, with a discounted payback of 8.6 years. It is concluded that the high energy density of molasses offsets its acquisition cost, validating complete co-digestion as the most efficient configuration to optimize investment returns and consolidate the plant in the biomethane market.