Chipping whole trees for fuel chips: a production study
A time and motion study was conducted to determine the productivity and cost of an in-woods chipping operation when processing whole mall-diameter trees for biomass. The study removed biomass from two overstocked stands and compared the cost of this treatment to existing alternatives. The treatment stands consisted of a 30-year-old longleaf pine stand and a 37-year-old loblolly pine stand. In the longleaf pine stand, 71% of the trees removed were less than 5 in. dbh. In the loblolly pine stand, approximately 81% of the stems removed were less than 5 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 von was 24.61 minutes. The chip moisture content averaged 94.1 1% (dry basis). Using machine rates and federal labor wage rates, the in-woods cost of producing fuel chips was $9.1 8/green ton (gt). The cost of the biomass chipping operation ($1 5.1 8/91), including transportation, compared favorably to existing alternative treatments of cut-and-pile or mulching.