Chipping whole trees for fuel chips: a production study.

摘要

A time and motion study was conducted to determine the productivity and cost of an in-woods chipping operation when processing whole small-diameter trees for biomass. The study removed biomass from two overstocked stands in the Oakmulgee District, Alabama, USA, and compared the cost of this treatment to existing alternatives. The treatment stands consisted of a 30-year-old longleaf pine (Pinus palustris) stand and a 37-year-old loblolly pine (P. taeda) stand. In the longleaf pine stand, 71% of the trees removed were less than 5 inches in diameter at breast height (dbh). In the loblolly pine stand, approximately 81% of the stems removed were less than 5 inches in dbh. The harvesting system consisted of conventional ground-based harvesting equipment and a three-knife chipper that processed the biomass into fuel chips. The average production time to fill a chip van was 24.61 minutes. The chip moisture content averaged 94.11% (dry basis). Using machine rates and federal labour wage rates, the in-woods cost of producing fuel chips was $9.18/green tonnes (gt). The cost of the biomass chipping operation ($15.18/gt), including transportation, compared favourably to existing alternative treatments of cut-and-pile or mulching.