Estudo sobre a obtenção de biomassa microalgal como matéria-prima para a produção de biodiesel

Abstract

The use of oils extracted from microalgae as a feedstock for biodiesel production can be considered a plausible strategy to assist the replacement of non-renewable energy and circumvent future scarcity of fossil fuels. However, in the process of producing biodiesel from this feedstock, there are certain biological, technical and economic aspects that have not been solved yet. In this sense, considering that the stage of microalgae harvesting is characterized as the most financial and energy onerous, in relation to the entire production process, the aim of this study was to conduct a literature review on the different stages in the process of biodiesel production from microalgae, with particular attention to the microalgae harvesting phase, in order to perform an operational and financial analysis regarding the most promising techniques belonging to this stage. Therefore, an operational and financial analysis of the costs (investment and operation) of flocculation and sedimentation were performed, because these were the techniques that better elucidated results regarding the efficiency of the biomass recovery and the lipid content presented in the recovered biomass. In addition, it was analyzed the sedimentation time in relation to the physical behavior of the microalgae (in unicellular and multicellular form shape) and, finally, it was estimated biomass productivity in function of the photosynthetic capacity of the microalgae on the solar energy incidence in the city of Londrina - PR. The results showed that the sedimentation must be performed as a secondary operation of the harvesting process and must be preceded by other mechanisms to promote aggregation of particles in order to increase the overall efficiency of the recovery of the microalgae biomass. It was verified that the process of biodiesel production through microalgae has its economic viability guided by two main points: the increase of scale production, in order to spread the investment costs; and the optimization of microalgae cultivation aiming at obtaining higher biomass productivities in order to encourage the minimization of operating cost in the harvest stage. Finally, it was concluded that the conversion efficiency of light energy in biomass by growing microalgae, in contrast to the maximum theoretical conversion efficiency is shown as an indicator of the need for optimization of microalgae cultivation for biodiesel production.