Stump and coarse root biomass from eucalypt forest plantations in a commercial-scale operation for bioenergy

Abstract

Bioenergy can contribute to low-carbon economy of Latin-America and African countries, where the biomass is a viable alternative to obtain a global energy matrix. The harvesting forest residue left on the ground of industrial tree plantations appears an option to be a biomass source to supply a combined heat and power plant. The goals of this study were to know the biomass production and the fuel quality of stumps and coarse roots from a commercial-scale harvesting operation of Eucalyptus under coppice regime in Brazil. To accomplish this objective, the stumps of two Eucalyptus commercial clones were evaluated entirely. Forest inventory data were combined with sampling procedures of the stump (which was removed with a front wheel loader) to obtain the biomass production. The physical and the chemical composition of stumps and roots were determined at the laboratory according to ASTM standards. Guiding values for concentrations of combustion-relevant elements in solid biofuels were introduced. The results showed that stump and its properties were statistically affected by variation factors (clone and rotation). The properties qualified the use of eucalypt stump and coarse roots biomass for energy purposes and suggested a minor unwanted component formed during the burning. Stump biomass production was at least 36 Mg ha−1 after six years of planting, totaling an energy yield of 626 GJ ha−1. Although the results found were suitable for the bioenergy scenario, the environmental sustainability of stump harvesting on forestry site must be studied carefully before its indiscriminate use.