Stacking factor in transporting firewood produced from a mixture of Caatinga biome species in Brazil

ABSTRACT The energetic requirements of the Brazilian gypsum industry are mainly provided by firewood transported by road. The cost of transporting firewood is greatly affected by the stacking factor. In this study, we determined how the stacking factor for trailer trucks varied for the firewood harvested from forest species in the Caatinga biome, Brazil. For this purpose, the following steps were carried out: i) the logs were stacked in a frame (volume, 1 stere) and weighed; ii) the solid over bark volume of each log was obtained by scanning and by xylometry (immersion in water); iii) the stacked volume of logs on the truck was measured; and iv) the stacking factor, the stacking density and the apparent density of the unpeeled wood were computed for each of 60 truck trips. The stacking factor was, on average, 1.12. This value is lower than reported for other species; the greater compaction of the timber represents an advantage in terms of transport costs. However, the maximum variation in the load weight was 20%, which is not negligible from an economic point of view because of the associated loss of energy efficiency in the supply chain for the lowest volume loads.