Efficiency of a compactor in wood chip volume reduction

The baling of freshly harvested wood chips was tested in an Orkel MP2000, a baling machine extensively used in agriculture and industry to densify residues. Wood chips from two different feedstocks: poplar (Populus x euroamericana) and black locust (Robinia pseudoacacia). Baling effected a volume reduction of 43% with respect to the loose bulk density of the piled chips. Each bale has an average mass of 638 kg, and the time consumption to produce one bale was typically 98 s - 122 s. Productivity then varied from 19.8 t h−1 and 21.7 t h−1 of the fresh (green) wood chips. Diesel fuel consumption ranged from 1.4 L t−1 to 1.5 L t−1 of fresh chip weight and represented about 12% of the production cost. The packaging cost is approximately 23 € t−1 of fresh chips equivalent to a bale cost of 15 €. Comminuted wood pressed into bales could provide a valid solution in the use of conventional agricultural and forestry machines. In fact, the handling and transportation of bales can be performed by means of equipment normally used in other agro-forestry activities (front loaders of tractors). In addition, pressed woodchips in packaged bales with waterproof sheets also guarantees a useful storage technique with significant storage surface reduction relative to loose wood chips.