The challenges of harvesting and drying short rotation coppice willow to meet the quality constraints of small scale boilers

摘要

Short rotation coppice (SRC) willow chipped during harvesting must be placed in a drying system shortly after harvesting if heating and fungal deterioration are to be avoided. In a study in which two batches of SRC willow were intensively monitored during periods of on-floor drying the system operated satisfactorily when ambient conditions were relatively mild (> 10°C). However, the time taken to dry the woodchip and the costs for electricity and heating more than doubled when the average ambient air temperature dropped below zero. Under these conditions it would be uneconomic to continue to dry the material and the carbon saving from its use would be < 50%. Harvesting SRC willow as a) whole rods or b) round bales allowed to dry naturally can bringthe material to below 30% and 20% moisture respectively, but for the round bales an effective method of chipping to meet the required quality standards has yet to be developed.