Caracterização energética da madeira e do carvão vegetal de Schizolobium parahyba var. amazonicum cultivado em sistema silvipastoril e indicações de uso

Abstract

Schizolobium parahyba var. amazonicum (Huber ex Ducke) Barneby, known as paricá, is a forest species native to the Amazon, widely cultivated in agroforestry systems due to its rapid growth and biomass production potential. To evaluate the energetic quality of the wood and charcoal of Schizolobium parahyba var. amazonicum cultivated in different silvicultural strata, as well as the suitable diameter for energetic use of residues, aiming at their utilization in combustion and carbonization processes. Analyses of basic density, chemical composition (molecular and proximate), calorific value, energy density, and thermogravimetric analysis of the wood were performed, in addition to controlled carbonization of samples with diameters greater than 10 cm to determine gravimetric yields and characterize the charcoal. The average basic density of the wood was 314.50 kg m⁻³, showing no statistically significant difference among the strata. The average total extractives content was 3.82%, with statistically significant difference between strata 1 and 3. The average total lignin and holocellulose contents were 27.94% and 67.84%, respectively. The remaining parameters showed no significant differences among the strata for the respective analyses. The proximate chemical composition of the wood presented average values of 83.26% volatile materials, 16.33% fixed carbon, and 0.40% ash. The average higher heating value of the wood was 4600.95 kcal kg⁻¹ and the average energy density was 1447.04 Mcal m⁻³. Carbonization resulted in an average gravimetric yield of 30.50% and charcoal with an average apparent density of 142 kg m⁻³. The proximate chemical composition of the charcoal presented average values of 20.79% volatile materials, 76.57% fixed carbon, and 2.64% ash, while the average higher heating value was 7240.66 kcal kg⁻¹ and the average energy density of the charcoal was 1021.01 Mcal m⁻³. Paricá wood indicates potential for use in direct combustion, due to the higher energy density in relation to charcoal, and may also be destined for heat generation in boilers and for the production of densified fuels, such as pellets and briquettes. On the other hand, although charcoal presents lower energy density, its chemical characteristics indicate potential for specific applications, such as biochar or activated carbon. Thus, paricá demonstrates versatility for multiple energy uses, allowing differentiated biomass utilization according to the diameter of the fractions and the intended energetic purpose in agroforestry systems.