The characteristics of wood and charcoal depend on the genetic material and the sampling position on the tree trunk. The objective of this study was to evaluate the effect of clone and longitudinal position on the characteristics of wood and charcoal of Eucalyptus grandis x Eucalyptus urophylla. Specimens belonging to I144 and GG100 clones both at seven years of age were felled and mechanically processed for disc removal at different longitudinal positions of 0, 3, 6, 9, 12 and 15 meters from the ground. The wood and charcoal physical and energetic characteristics were evaluated according to the different longitudinal positions. The genetic material and longitudinal position influenced the wood and charcoal characteristics. Sampling positions on the tree trunks can be considered for the energetic direction of "in natura" or carbonized biomass.

In this study, the physical and chemical characteristics of Bambusa vulgaris ex J.C. Wendl. var.vulgaris (Bambusa vulgaris) aged 1, 2 and 3 years were evaluated. The objective was to train, validate and evaluate the efficiency of artificial neural networks (ANNs) as predictive tools to estimate bamboo stem energy density grown commercially in northeastern Brazil. For that, samples were collected in a commercial plantation and managed for energy production, determining the energy properties. Among all the characteristics analyzed, basic apparent density was the one with major correlation with bamboo stem energy density. This factor has a great advantage because it is easy to estimate, determined both by dry mass at 0% moisture, and at saturated mass. Also, the precision of ANNs was verified when associated with basic density, as a predictor of bamboo stem energy density, showing low standard error (Syx%, 1.52) and high coefficient of determination (R² = 0.98). ANN-estimated values had no statistical difference (t cal 0.58 ≤ t tab 2.08) with energy density estimated in the laboratory. Therefore, this tool was efficient, being recommended to predict the energetic density of the species under study, with basic density as the only predictive variable.

RESUMONa análise do potencial energético de um resíduo, além da qualidade do mesmo, a quantidade também deve ser observada. Às vezes têm-se diferentes resíduos que, isolados, não atendem a uma das premissas ou ambas. Nesse caso, é necessário o estudo do potencial energético de misturas. O objetivo deste trabalho foi avaliar o potencial energético de misturas de serragem de madeira de eucalipto com resíduos agrícolas e dos briquetes produzidos a partir dessas misturas. Para produzir os briquetes, foi utilizada uma briquetadora de laboratório com temperatura de 120 ºC, pressão efetiva no briquete de 100 BAR por um tempo de 5 minutos e resfriados por 10 minutos. Os briquetes provenientes da mistura de casca de baru + eucalipto mostraram-se mais promissores, pois, mesmo com maior umidade e menor densidade, apresentaram maior poder calorífico inferior, o que propiciou uma das maiores densidades energéticas. PALAVRAS-CHAVE: adensamento, caracterização, energia, resíduo. ENERGY ANALYSIS OF BRIQUETTES OF Eucalyptus spp., Dypterix alata, Caryocar brasiliense and Musa spp. RESIDUES ABSTRACTIn an analysis of the potential energy of residues, beside the quality of it, the amount of residue should also be observed. Sometimes, there are different types of residue, that isolated, do not meet one of the premises or both. In this case, it is necessary to study the potential energy of the mixture. The aim of this study was to evaluate the potential energy of the mix of sawdust of eucalyptus wood and agricultural residue and of the briquettes produced from this mixture. To produce the briquettes, it was used a briquetting machine with a temperature of 120 ºC, the effective pressure on the briquette was 100 BAR for a period of 5 minutes and then it was cooled down for 10 minutes. The briquettes from the mixture of eucalyptus and Dipterix alata husk appeared to be promising, because even with highest humidity and lowest density they presented highest calorific value and resulted in one of the largest energy densities.

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