Utilization of vineyard prunings: A new mechanization system from residues harvest to CHIPS production

Italian wine-making covers 18.4% of global production and represents the world's largest production. Cultivation of the vineyards foresees the winter pruning necessary for preparation of the next year's production. The annual pruned biomass (1-3 t ha−1) is considered waste and is managed by shredding or burning. The possibility of taking advantage of the pruned material in order to obtain biomass for heating purposes represents an alternative that can turn waste into a further product of the vineyard. The easiest form in which to manage the pruned biomass for energy purposes is that of wood chips. Chipping, however, requires specific equipment and has to deal with the problem of residual humidity. Moreover, transport to a processing center represents a critical extra cost. Aim of this study was to evaluate the feasibility of a new mechanization system based on the harvest of the pruned biomass in small diameter (450 mm) round-bales, their natural drying in stacks and then in chip the whole round-bales with a purpose-designed mill, powered by the tractor power take-off (PTO) itself. The trials, carried out in a typical North-West Italian wine-producing area, show that the bottleneck represented by the high water content of prunings directly chipped in field, doesn't represent a limit with the proposed system that foresees a period (4 months) of natural drying of round baled prunings before their energy (thermal) use. Further transformation processes for bulk density increase (i.e. pellet formation) have been considered as upgrade of the system.