Bojana Klasnja

Wood and bark of some poplar and willow clones as fuelwood

Abstract Poplars and willows are widely used to produce biomass for energy. Calorific values of wood and bark, as well as for whole tree of Populus × euramericana (cl. I-214), Populus deltoides (cl.PE 19/66) and white willow Salix alba (cl.378) of different ages were determined. one- and 2-year-old rooted cuttings were grown in plantations with high planting density, in order to produce a high biomass yield per hectare. Mature trees in both species (poplar and willow) originated from the corresponding plantations; willow 14-year old, and poplar 12 years (cl.I-214) and 8 years (cl.PE 19/66). As the share of bark depends on the age of wood, calorific values were determined separately for bark and for wood. The share of bark (proportion of total weight) in 1- and 2-year-old rooted cuttings ranged between 18% and 27%, and in older trees it was from 10% to 15%. The higher heating values of oven dry poplar wood (calculated for the whole tree, based on the proportion of bark) were from 15,787 (cl. I-214 1-year old) to 24,275 kJ/kg (cl.I-214 2-year old). The average calorific values of willow wood (whole tree with bark) were from 16,169 (14-year old) to 22,572 kJ/kg (2-year old). It should be pointed out that the calorific value of wood is more favorable than that of bark, and the highest calorific values refer to 2-year-old trees.

Dense poplar plantations as the raw material for the production of energy

The higher heating value of wood and bark was determined for several poplar (Populus spp) clones. The study included the juvenile one year old plants of the following clones: P.×euramericana cl. ostia, P. nigra cl.53/86, P. deltoides cl. PE 19/66, P.×euramericana cl. I-214, P. deltoides cl. S6-7 and P.×euramericana cv. robusta. By using FVI which takes into account ash content, wood bulk density, and moisture content, it was determined that poplar wood can be a significant energy raw material, primarily thanks to its short rotation cycle and a very high wood volume increment. Significant differences were determined in the values of wood basic density which affect the higher heating value of the study poplar clones, and consequently the yield (weight) of biomass produced per unit area of dense plantations. This is reflected also on the estimated amount of energy that can be produced by the combustion of biomass of the whole one year old plants.