Energy quality of charcoal from five eucalypt genotypes under two irrigation regimes in the Brazilian semiarid region

Brazil is a global leader in the use of eucalypt for multiple purposes, including charcoal production for energy and metallurgical applications. However, the effects of irrigation regimes on charcoal quality in eucalypt genotypes grown under semiarid conditions remain poorly understood. This study evaluated the energy quality of charcoal produced from the wood of five eucalypt genotypes cultivated under two irrigation regimes (12 and 36 months) in the Brazilian semiarid region. Four trees per genotype were sampled at 11 years of age, and 5.0 cm-thick stem disks were collected at 0 (base), 20, 40, 60, and 80% of the commercial height (minimum diameter of 6.0 cm). Carbonization was performed under controlled laboratory conditions. Physical, chemical, and energy properties of the charcoal were determined, and the data were analyzed using ANOVA and principal component analysis (PCA). Gravimetric charcoal yield ranged from 37.7% to 41.2%, and higher heating value varied between 6784 and 6921 kcal kg−1. Bulk density (350–0.430 kg m−3) was significantly affected by irrigation, with higher values under the 12-month regime. Clones GG680 and GG702 demonstratedsuperior performance, combining high bulk and energy density with low specific consumption, making them suitable for energy and metallurgical uses. PCA indicated that fixed carbon content, higher heating value, and density were key variables for genotype selection. This study provides novel insights by explicitly linking genotypic performance with water management strategies under semiarid conditions, addressing a critical knowledge gap and providing technical support for sustainable forestry.