It is possible to combine the maneuverability of small trucks with the long-haul efficiency of large semi-trailers by using a concentration yard to improve logistics [6]. Concentration yards, also known as sort yards for roundwood, are intermediate transfer points where material is collected. In the forest sector, they typically serve to improve logistics in transportation, processing, storage and marketing. For sites that are inaccessible to large chip vans, smaller trucks can be used to transport material over forest roads to a site with better road access. Biomass can then be transferred to large trucks with higher payloads to cover long on-road distances to end users. Similarly, when harvest sites are widely dispersed, difficult to access, and have relatively small amounts of material to process, it is costly to move processing equipment from site to site. In this case, logging residues and roundwood can be transported from harvest sites to a central location, stockpiled, and then processed in large volumes, which increases processing efficiency. This logic can also be applied to pretreatments, which are discussed in more detail later in this chapter. In some cases, processing and pretreatment equipment cannot be transported to harvest units due to poor road conditions or design limitations, making a concentration yard necessary. In both cases, gains in transportation and processing efficiency must be balanced against added handling costs, with concentration yards requiring additional unloading, handling, and re-loading components. In general, the costs of double handing low-value material like woody biomass are very difficult to recover by improving transportation efficiency, unless transportation costs are extremely high.

Concentration yards can also provide off-site storage of raw material, either in its raw or processed/pretreated form. This may be an attractive option in areas affected by seasonal road restrictions that limit access to material at harvest sites for part of the year. In addition, though less relevant for woody biomass than for high value roundwood products, concentra­tion yards can be used to improve efficiency in product marketing by separating aggregate deliveries of logs from harvest sites into fuelwood, pulpwood, and different grades of sawlogs for shipment to different facilities [7]. Typically, this is done on the log landing or at a facility that uses its log yard as a sort yard, shipping loads of logs to other facili­ties, but there are some conditions where it may make sense to incorporate this approach into woody biomass logistics. As with the storage and processing aspects of concentration yards, the added costs must be weighed against added revenues of product sorting and marketing. Though they are used in road-based logistics systems, concentration yards are a necessity when woody biomass is going to be transported by rail or ship. Though extremely rare because of its unfavorable economics, biomass removals by helicopter also require a concentration yard. For railroad transportation, rail-side concentration yards allow material to be stored on site and transferred efficiently into rail cars and shipped after sufficient material is stockpiled.