A segregação de resíduos do manejo florestal sustentável para otimização da produção bioenergética na Amazônia brasileira

Abstract

Logging wastes from sustainable forest management in the Amazon are promising for energy purposes, however, they are highly heterogeneous (dimensions and technological properties). When used without segregation, it results in low energy efficiency in local thermochemical processes. Thus, this work aimed to contribute to the energy optimization of logging wastes from sustainable forest management, aiming to serve the energy systems in the Brazilian Amazon. The wastes were sampled three days after logging at the Forest Management Unit from Rio Capim Farm in Paragominas, Pará. The largest diameter branches of three trees of twenty species of occurrence in the Brazilian Amazon were sampled. Three wooden discs from the base of the branches were collected to support identification in the xyloteque, wood analysis and carbonization in laboratory scale. In addition, botanical material was collected to support species identification. The study was divided into four chapters to facilitate compression. The first one shows the relationships between the colorimetric parameters and the basic and energy densities of the logging wastes. The second reports the physical, chemical and energy characteristics of the wastes, and the properties that influence the energy performance of the firewood. The third treats of the production and quality of charcoal in a laboratory scale. The last chapter reports the main contributions of logging wastes segregation on brick kilns productivity and carbonization yields. Correlations involving the colorimetric parameters (L*, b*, C* and h*), basic density, and energy density were evidenced. Thus, woods with higher red pigmentation (a*) (Manilkara elata and Dinizia excelsa) are denser and have more stored energy (Chapter 1). The total extractives presented a wide variation among logging wastes (1.85% - 17.88%) and it was the chemical property that most influenced the energy performance of the firewood. The logging wastes were segregated into 4 groups of similar technological properties for power generation in the Amazon based on Principal component analysis (Chapter 2). Wood extractives positively influenced charcoal yield, mass balance of carbonization, heating value and fuel index value of charcoal (Chapter 3). The segregation of logging wastes into groups with similar properties based on multivariate analysis promoted positive effects on carbonized raw material content, kiln productivity and carbonization yields (Chapter 4). This study has a positive impact on science and the local productive sector. As for science, it was evidenced that the energy quality of the native wood wastes of the Amazon was more influenced by the total extractives, and therefore, should be considered in the residual biomass qualification. The segregation of logging wastes into groups with similar properties resulted in real gains in energy conversion efficiency, showing lower consumption of firewood for the same amount of conventionally produced charcoal. Thus, the improvement of the rates promoted by segregation contributes to the sustainability of energy systems in the Amazon, especially charcoal plants, emitting fewer gases and producing more charcoal.