A Critical Review of Comminution Technology and Operational Logistics of Wood Chips

Purpose of the Review: This review offers essential information on the factors affecting the efficiency of wood chip supply chains, and of comminution in particular. The paper indicates the pros and cons of alternative set ups, as well as the impact of specific technical choices, including machine setup and adjustments. Recent Findings: Chipping performance is closely related to chipper characteristics and setup, and to feedstock type. In general, productivity is directly proportional to chipper power and piece size, as far as the latter is within the capacity of the machine in question. Blade wear, cut length, and screen size also have a strong impact on productivity and work quality--and so do operator experience, skill, and motivation. Daily production is affected by work organization and machine reliability: delay time may represent between 25 and 50% of actual work site time--occasionally more, especially when the interface with the transport fleet is not properly managed. Summary: Wood biomass supply chains are characterized by comminution as their central process, since all automatic wood boilers require comminuted wood. Different supply chains are defined by what kind of feedstock is comminuted and where comminution takes place. In principle, one can comminute whole trees, logs, or logging residues--and comminution can occur on the cutover, at the landing or in a yard--be it a terminal or the factory wood yard. Comminution can be obtained by chipping, grinding, crushing, or shredding. Chipping is by far the most common method and is applied in different ways depending on work conditions.