Potencialidade de uso bioenergético da madeira e da casca de Eucalyptus spp. plantados em espaçamento adensado e sistema de curta rotação

Abstract

This research aimed to evaluate and classify the wood and bark quality of nine clones and two seminal (seeds) materials of Eucalyptus spp. planted under dense regime, with short rotation harvest, and indicate its potential use for bioenergy, especially direct burning and charcoal. The sampled material was obtained from plantations of the Carvovale Company, located in Taiobeiras City, Northern Region of Minas Gerais State, Brazil. Nine clones and two seed materials at 24 months of age were used. Eight clones were planted of 4.0 m x 0.5 m spacing and one clone and the seed materials were planted in spacing of 3.0 m × 1.5 m × 1.0 m. The individual volume, basic density, elemental chemical analysis, holocellulose, total lignin, total extractive, ash, fixed carbon and volatile materials content, higher and lower heating values, dry mass, energetic density, carbon and minerals amount were determined in both, wood and bark. The wood carbonizations were conducted in electric kiln, employing a heating rate of 1.67oC per minute until the final temperature of 450oC, remaining for 30 minutes. In the produced charcoal were determined the gravimetric yield of carbonization, immediate chemical analysis, apparent relative density and higher heating value. A completely randomized design (CRD) arranged in factorial scheme (11 x 2) with five replications was used to analyze of the wood and bark characteristics. To evaluate the yield and charcoal quality the CRD was used with three replicates. The Scott-Knott test was used for multiple comparisons, at 5% significance level. The results showed that both wood and bark of the evaluated genetic materials presented potential use as energetic source, especially for direct burning. Despite the average fixed carbon content of the charcoal produced remaining below 75%, value recommended for steel industry, most evaluated clones presented satisfactory traits for charcoal production.