Determinação dos potenciais técnico e econômico da geração de eletricidade a partir da biomassa: estudo de caso do estado de Minas Gerais

Abstract

The present investigation aims to determine the technical and economic potentials of electricity generation from different types of biomasses in the state of Minas Gerais, using different electricity generation technologies, supported by different thermochemical combustion and gasification routes. The five most available biomasses in the state of Minas Gerais were selected: corn, soybeans, coffee, eucalyptus and sugar cane, whose crops produce residues that can be used for electricity generation. Considering the technical, logistical and economic data of the selected biomasses, the research sought to define the most viable types of residual biomass for electricity generation, in different locations within the state, through a multi-criteria decision-making approach (MCDM). A bibliographic review of the maturity of different types of electricity generation technologies from biomass was carried out, based on available information, schemes and operational parameters of real installations. The level of technological readiness of the different alternatives was also evaluated through a survey with specialists in the sector, concluding that the technologies with the highest level of readiness are the conventional Rankine cycle, the organic Rankine cycle and the use of gasifiers integrated with internal combustion. These three technological alternatives were adopted as options for the generation of electricity from biomass, obtaining a scale of the types of biomasses available, through a multicriteria methodology. The determination of the criteria weight was carried out from an integration with the analytical hierarchy process (AHP). In conjunction with a GIS-MCDA approach, different micro-regions were evaluated considering their respective biomass resources, allowing the estimation of costs and performance of different electricity production technologies. A logical algorithm was developed for the selection of alternatives for energy production from biomass, giving priority to technical feasibility, and considering factors such as the availability of biomass and its characteristics such as calorific value, humidity and granulometry. Investment costs, operating costs, as well as logistical costs for generating electricity from the plant, according to the technology used, were surveyed. Typical energy efficiencies for these cycles are between 8 and 30%, with conversion efficiency increasing with generation scale. To be analyzed, the generation systems were divided according to their power ranges in industrial application through power curves, in which plants with power above 5 MWe were to use the conventional Rankine cycle, power between 0.5 and 4.1 MWe using organic Rankine cycles, and the lower capacity potentials adopting the gasification and syngas burning cycles in internal combustion engines. It was found that eucalyptus prevailed as the most suitable biomass for most of the cases analyzed, due to its high energy power, followed by sugarcane residues, which are produced in greater quantities in the state. The conventional Rankine cycle was identified as the most mature technology and also had the lowest generation costs. In the projects that showed economic viability, the generation costs were between US$ 0.10/kWh and US$ 0.24/kWh.