Características de crescimento, madeira e carvão para classificação de clones de Eucalyptus spp. visando o uso energético

Abstract

This study aimed to use the growth, wood and charcoal characteristics to classify of different genetic materials Eucalyptus for energy purposes. Thirty-nine 39 Eucalyptus spp. clones, at 81 months of age, sampling three trees per genetic material were evaluated. The research was divided into four main topics to facilitate comprehension: I – preliminary classification of Eucalyptus clones; II – wood combustibility of the selected clones; III – production and quality of charcoal of the selected clones, and; IV – identification of wood quality indexes for charcoal production. The results indicated that the estimates of wood dry mass and carbon dry mass were the variables that most contributed for total genetic divergence, being decisive in grouping and classifying the Eucalyptus clones for energetic use. Fourteen clones were selected by means of the cluster analysis for topics II, III and IV. After this, physical, chemical and thermal analyses in wood were performed to obtain heat. In the topic II was observed clonal effect on the wood combustibility. The individual energy productivity, unit energy density, extractive soluble in acetone, lignin, volatile materials and fixed carbon contents, maximum combustion rate and amount of guaiacyl units per wood dry mass were considered the main quality indexes of wood for classifying Eucalyptus clones aiming at complete combustion. In the topic III the clonal effect, in general, influenced the properties and productivity of charcoal. The results obtained in the topic IV indicate should be selected Eucalyptus clones of higher basic density wood, elevated lignin content and extractives soluble in acetone and greater amount of guaiacyl structural units (G). These characteristics can be considered as the main wood quality indexes for the charcoal production. The gravimetric yields of the slow pyrolysis process and the charcoal quality are more related to the guaiacyl structural units content (G) than S/G relation. Clones 1009 and 1037 were indicated to use for charcoal production and combustion, respectively. Finally, the S/G relation can be a nonreliable index for classifying Eucalyptus clones aiming at heat generation and charcoal production.