The objective of this study was to evaluate the performance and to estimate costs of a wood chipping system for tree tops, which are considered residuals from wood harvesting, to be used for energy. The study was developed in a forest industry in the Para State, located in the north region of Brazil. The system was comprised by one wood chipper, two forwarders and one front loader. Data collection was based on time study, fuel consumption and chips load weighting. System average productivity was 17.51 tonnes per effective hour. Machine utilization rate was 51.9% due to many delays, mainly for repair and maintenance of the chipper. Chips transportation was considered to be the critical point of the system, due to some lack of trucks available for blowing chips. The system can produce between 94 and 162 times more energy than the energy consumed. System cost per effective hour was R$ 376.56, which means R$ 21.51/tonne of chips or R$ 2.70/GJ.
Forest biomass; Wood chipper; Renewable energy
