Storage of poplar wood chips in Northern Italy

The aim of this study is to evaluate the performance of different storage systems with various particle sizes of hybrid poplar in Northern Italy. The evaluation is based on changes in fuel quality, self heating of the material and microbial activity. Four piles were built using chipped poplar; compacted; covered; ventilated: and an uncovered pile. In addition, a pile of billet and whole trees pile were also studied. The trials were conducted during March-October. Changes in moisture content (MC), ash content and heating values were determined. Microbial growth was also assessed. No temperature development was detected in the pile containing whole trees poplar, while the billet pile maintained a temperature around 25°C. All the chip piles had an average of 60°C during the first two weeks of storage, slowly declining after word to below 50°C in the covered, uncovered and the ventilated piles. The highest temperature rise was measured in the compacted pile reaching 100°C and remaining well above 55°C for most of the storage period. The heating value per kg of the chipped poplar was generally higher after storage probably due to the removal of easily degradable nutrients through intensive microbial activity in all the treatments. A considerable decline in average MC was determined in the covered, billet and whole tree piles, and to a lesser extent in the uncovered pile