Resumo. This study aimed to evaluate the volumetric efficiency and energy produced by three different hybrid clones of Eucalyptus sp. C39 Hybrid Eucalyptus urophylla (natural crossing); C41 Hybrid Eucalyptus urophylla (natural crossing) and C11 Hybrid Eucalyptus brassiana (natural crossing). The Smalian method was used to quantify the volume of wood. The basic wood density and the calorific value were determined in accordance with their respective Brazilian Association of Technical Standards (1984 and 2003). The firewood consumption was obtained through the monitoring the calcination of gypsum. The statistical analysis was done considering a complete randomized design. The volumetric productivity of these 7.5 year-old clones were 158.46, 132.20 and 164.89 m³/ha, respectively. The amount of wood cubic meters, in form of logs, necessary for the calcinations of one ton of gypsum was 0.16, 0.10 and 0.13. However, when wood chips were used, quantities used were 0.11, 0.08 and 0.09 cubic meters per ton. These results of the calcination efficiency using wood chips were better than the best result obtained using the wood of native vegetation that was 0.16 cubic meters per ton.