PELLET QUALITY FROM BIOMASS OF EIGHT FAST-GROWING DENDROENERGETIC SPECIES

Abstract

The productivity of biomass in fast-growing species is one of the best alternatives for the elaboration of dendroenergetic biofuels. One of the most important pre-treatments of the biomass is pelletizing, with which calorific value is increased. The objective of the present study was to evaluate the quality of pellets of eight fast-growing dendroenergetic species. The species evaluated were Eucalyptus globulus, Pinus greggii, Populus alba, Acacia retinoides, Ricinus communis, Populus deltoides, Pennisetum sp. and Salix sp. The experimental design was completely randomized; the species were analysed as treatments. The data was used for an ANOVA and the means of the treatments were compared with the Tukey test (p≤0.05) The variables evaluated were: moisture content (CH), ash content, volatile material (CV), fixed carbon (FC) and gross calorific value (PCS); diameter, length, weight, volume, bulk density, specific density (DP), resistance index, biomass loss, and friability (F). The differences among species were significant (p≤0.05) for all of the variables. Eight out of nine species complied with minimum values of PCS (19.2 MJ kg^-1 and 20.1 MJ kg^-1) required in international norms of quality in pellets (18.0 MJ kg^-1). The pellets of eight species presented the dimensions required in the norms of quality. All of the species showed acceptable density, based on the international norm. In specific density high and significant values were observed in Pennisetum sp. (1.4 g cm^-3) and Pinus greggii (1.4 g cm^-3), while P. deltoides registered the lowest value (1.0 g cm^-3). In the resistance tests, the pellets of P. greggii presented high values for the number of parts at breakage (2.4) and loss of biomass (41.6 %); as well as low values of friability (0.45). Pellets obtained from the biomass of the evaluated species satisfied the international standards of quality.