Produção de energia renovável a partir do biogás em empreendimentos habitacionais: análise técnica, econômica e ambiental visando o desenvolvimento urbano sustentável

Abstract

In Brazil, a significant portion of domestic sewage is treated through anaerobic processes, which allows biogas energy recovery. In this context, this dissertation aimed to study biogas production and usage potential for decentralised energy generation in compact sewage treatment systems placed in residential buildings. For this, three establishments with distinct socio-economic characteristics were adopted and a technical and economic viability of the systems’ designed were analysed, as well as their environmental impacts. The volume of biogas produced in each building (8.7 to 21.6 m³.day-1 ) would allow generator to operate during some hours per day, which should preferably occur at peak times (when energy tariff is more expensive). Thus, it was detected that energy generation would not be enough to supply all demand of buildings’ common area, yet, the project would allow savings of approximately one month expenditures in a year. Results from economic feasibility analysis, with NPV of R$ 4,460.51 (RMo) and R$ 590.97 (RSv) for the situation where all projects’ expenses where accounted and of R$ 45,473.83 (RMo), R$ 33,639.05 (RSv) and R$ 88,959.44 (PAg) for the situation considering only biogas system costs, showed that savings from biogas use were sufficient to cover implementation, operation and maintenance expenditures in five of the six conditions evaluated. Moreover, since environmental benefits are plenty motives to include sustainable processes in new constructions and projects resulted in low per capita costs (R$ 49.91 to R$ 85.80 with CAPEX and R$ 3.96 – R$ 4.91 with OPEX annually), it was understood that the system presented great potential of application. Finally, technical feasibility analysis permited do conclude that the main obstacles would be related to biogas technology development in the region, specially about availability of adequate equipments for small biogas volumes and the lack of guidelines for project designing. Therefore, it was highlighted the need for complementary studies in order to encourage this sector, considering that environmental and economic conditions are advantageous.