Effects of different storage techniques on round-baled orchard-pruning residues

Abstract

Baled pruning residue could be a valid solution to reduce the storage surface area in thermal and electrical power station. This study aimed to analyze the storage performance of pruning residues baled by a round baler considering three orchard tree species (apple, peach, and kiwi) and three different techniques (uncovered, under roof, and wrapped). The storage parameters considered were: moisture content, dry mass, and wood energy content of the material. The initial moisture content of the tree orchard specie (apple, peach, and kiwi) was different: lower for peach (41%) and higher for kiwi (51%). At the end of the storage period, all bales (covered and uncovered) obtained similar values to that of the air (about 20%); wrapped bales have highlighted no moisture content variation. The tested tree species showed a similar initial high heating value (18.70 MJ·kg-1), but a different initial low heating value: lower for kiwi (7.96 MJ kg-1) and higher for peach (10.09 MJ·kg-1). No dry matter losses were observed in all test. Stored pruning residues in bales show good benefits in term of "biofuel" quality independent of the techniques adopted expect for the wrapping system that do not permit adequate drying of the biomass.