Costs and productivity of woody biomass harvesting in integrated stand conversion and residue recovery operations

Three separate forest biomass harvesting systems were selected to study the operational performance and costs of systems designed to recover sawlog harvesting residues and silviculturally restore forests through stand conversion operations. These systems include the use of hook-lift trucks to access remote forest residues, energy wood harvesters to collect and improve density of residues through bundling, and integrated operations for the production of both sawlogs and energy wood chips. The overall system productivities were significantly affected by adverse road hauling distances, slash pile material size and arrangement, diesel fuel prices, and appropriate pairings of machinery. Slash pile arrangement and material size were found to have a significant effect on productivity of loading loose slash into trucks and in the bundling of slash. Forest biomass that was not accessible using traditional highway chip vans was successfully removed from previously harvested timber sites with hook-lift trucks. Energy wood harvesters were effective in collecting and compressing slash into bundles, and can be successfully incorporated into centralized grinding operations. Integrated harvesting of both sawlogs and biomass was a good method for silviculturally restoring stands and to produce both high value sawlogs and energy wood chips. Total system costs ranged from $32.98/bone dry ton (BDT) for residue recovery operations including a hook-lift truck to $46.50/BDT for bundling operations. All operations studied accomplished removal of forest residues for renewable energy production without the practice of open field burning.