Análise comparativa entre geração de eletricidade e produção de biometano a partir do biogás: fundamentação teórica e estudo de caso

Abstract

The global climate crisis has intensified the need for measures aimed at mitigating Greenhouse Gas emissions, within the context of the energy transition, in which the search for technological alternatives capable of promoting greater sustainability and efficiency in energy generation has become imperative, with emphasis on the replacement of fossil-based sources by renewable ones. In this context, the objective of this work is to perform a techno-economic comparative analysis between two biogas utilization routes: electricity generation and biomethane production. For this purpose, a real biogas plant located in the interior of Brazil is used as a case study, allowing the evaluation of the alternatives in a practical operational context. The results indicate that, although electricity generation is a consolidated alternative integrated into the Free Energy Market, it remains subject to the volatility of the Settlement Price for Differences and to the hydrological conditions of the country. From an economic perspective, the biomethane route presents a promising revenue structure, with lower exposure to Price for Differences fluctuations that affect electricity generation. The analysis is characterized as a replacement decision, in which an incremental cash flow approach is adopted to compare the alternatives. Thus, cash flow projections were carried out for both the current electricity generation scenario and the proposed biomethane production scenario. The analysis considered both the standalone evaluation of the new project and the incremental analysis relative to the existing operation. The economic feasibility of the transition is assessed using Net Present Value (NPV) and Internal Rate of Return (IRR) indicators applied to the incremental cash flow, resulting in an NPV of R$ 91,875,107.43 and an IRR of 27%, demonstrating the attractiveness of the investment. It is concluded that biomethane production presents higher economic viability compared to electricity generation, representing a more advantageous alternative for the project. However, the results are dependent on the assumptions adopted, particularly regarding market prices and operational costs.