Case study: Kevelopment of a swath harvester for small diameter (<10 cm) wooody vegetation

摘要

A 216 kW biomass harvester, modified from a John Deere silage harvester, was field tested in Texas and New Mexico to examine the productivity and cost of harvesting shrubs and small trees for energy purposes. The harvester was tested on mesquite (Prosopis glandulosa var.glandulosa)in Texas and salt cedar (Tamarisk pentandra) and pinyon (Pinus edulis)/juniper (Juniperus monosperma) stands in New Mexico. While the harvester severed and chipped a few individual 20-cm basal diameter trees, the harvester was much more efficient harvesting dense stands of small trees that were less than 10-cm in basal diameter. During the course of these trials, major modifications were made to increase the efficiency of the cutterhead and the materials handling system. After these modifications, when harvesting mesquite stands less than 10-cm in basal diameter, the machine harvested at the rate of 0.95ha h~-1 with a fresh weight harvest production of 7050 kg h~-1. Using $70 h~-1 operating cost data for simular commercial equipment ,we estimated an energy cost of $1.00 kg h~-1 which compares fafvorably to energy sources such as low sulfur Wyoming coal, natural gas and fuel oil.