Viabilidade econômica do biogás proveniente do tratamento de resíduos orgânicos do consórcio da região metropolitana de Sobral (CE)

Abstract

The large generation of waste is one of the problems that will always need to be faced, as poor management can end up causing serious environmental problems. The search for technical solutions for the treatment of solid waste is essential. the digestion Anaerobic is one of the most promising methods for the treatment of organic residues, because in addition to disposing of waste, it produces biogas, a source of renewable energy. Nonetheless, To operate effectively, it is necessary to align the environmental sphere with the economic. The aim of this study was to evaluate the technical-economic viability of the use of biogas obtained from the anaerobic digestion of solid waste organic resources generated by municipalities belonging to the Integrated Management Consortium of Solid Waste from the Metropolitan Region of Sobral (CGIRS-RMS), Ceará, in a horizon 10 year project. For this, 3 scenarios were considered: sale of electricity (scenario 1), sale of biogas to concessionaire (scenario 2), use of biogas as vehicle fuel source (scenario 3). First, the calculation of the dimensioning of the biodigester used, together with the design company, from the estimate of organic waste generation. Afterwards, the price of the equipment necessary for the construction of the biogas plant, as well as the costs and taxes involved. Based on this, for the economic analysis itself, a statement of income for the year (DRE) for calculating the cash flows related to to the years of the project and the analysis of economic indicators: net present value (NPV), internal rate of return (IRR) and payback time, using a minimum attractiveness rate (TMA) of 14% p.a. For the analysis of the results, 4 cases were adopted for each of the scenarios: economic analysis without additional income (Case 1), economic analysis considering the recipe for not disposing of organic waste in the landfill (Case 2), analysis economic analysis considering the revenue from the sale of carbon credits (Case 3) and, finally, the economic analysis considering these two additional revenues (Case 4). For Case 1, the scenario 1 proved to be economically unfeasible with a negative NPV of R$ 7,893,785.56, IRR of 6.5% and payback of 16.96 years. Scenarios 2 and 3 have already proved to be viable economically, with positive NPV values ​​of BRL 3,101,979.12 and BRL 37,544,853.27, IRR of 17.3% and 49.1% respectively. For Case 2, scenarios 1, 2 and 3 proved to be viable economically, with positive NPV values ​​of R$ 17,450,969.91, R$ 28,446,734.60 and BRL 62,889,608.75 respectively, IRR of 28%, 40.4% and 69.4% respectively and payback of 4.91 years, 3.17 years and 1.73 years respectively. For Case 3 scenario 1 continued unviable, with a negative NPV of R$ 3,057,957.05, IRR of 11.2% and payback of 12.38 years. Scenarios 2 and 3 already proved to be economically viable with positive NPV of BRL 7,937,807.64 and BRL 42,380,681.79 respectively, IRR of 22.3% and 52.3% and payback of 5.99 years and 2.3 years respectively. For Case 4, all scenarios were feasible economically.