Evaluation of Large Scale Willow Biomass Crop Harvesting Using a Recently Developed Single-Pass Cut-and-Chip Harvest System.

Demand for bioenergy sourced from woody biomass is projected to increase; however, the expansion and rapid deployment of short rotation woody crop (SRWC) systems has been constrained by high production costs and sluggish market acceptance due to problems with quality and consistency from first-generation harvesting systems.  Harvesting accounts for about 30% of the delivered cost in SRWC systems such as willow and poplar; harvesting and transport combined can account for 45-60% of delivered costs.  The objective of this work was to evaluate and improve a single-pass cut-and-chip harvester based on a standard New Holland FR-9000 series forage chopper with a dedicated 130FB short rotation coppice header in conjunction with several chip collection systems.  Using an iterative process of field testing and optimization, harvester production rates and reliability have increased dramatically over three years and across 120 harvested hectares.  Chip quality was very good and consistent with most of the chips being less than 38mm in size. Willow biomass moisture contents ranged from 39 to 48% with the majority of samples between 43 and 45%.  Rates of biomass delivered to the edge of the field has progressively increased from 9 wet Mg/hr, to 35-41 wet Mg/hr, while harvester-related down time has decreased from 74% to below 5%.  Although median harvester speeds on gentle terrain were near 4-5 kph in mature willow crops compared to 10 kph in young poplar, production rates were similar; meaning, ground speed is not necessarily a good predictor of production rates in SRWC systems because dense stands and certain stem forms are more resistant to the forward progression of the harvester.  Also, given the strides in harvester production and performance, limitations to the overall system efficiency have shifted from the harvester to the collection system, or as affected by site conditions.