PRODUCTION OF WOOD ENERGY BY CHIPPING
Increasing demand for using renewable energy resources is strongly emphasized during the last decades. On the international level it is recognized through a series of conventions, conclusions and recommendations. Forests are energy source through conversion of wood biomass into solid, fluent and gaseous fuels for industrial and household use. Wood chips is a form of biomass, size of 5-50 mm, which is obtained by chipping of lower quality logs, trees, brushwood and wood residues. Some investigation showed that choosing the right chipper is crucial in a projection of chipping system. In this study, chipping at the landing site was compared with the Jenz HEM 700 and Pezzolato PTH 1300/1500 chippers. The subject of chipping was beech long fuelwood and stacked fuelwood. The investigation was done with the time and work-study method. Cost calculation was performed according to FAO methodology, slightly modified for local conditions. Also, in simulations, Jenz HEM 561 DQ was included in order to cover a wider range of chippers by the capacity, but data for this chipper were undertaken from other research. Unit costs of chipping were calculated on the basis of raw material input and chipper output. Unit costs were expressed for factory projected chippers productivity also, in order to compare obtained unit costs with costs when chippers are working below full capacity. Results of the productivity and cost calculation of chippers showed that bigger chippers had lower unit costs, but because of inability to achieve full capacity at the forest landing site and because of their dimensions which hinder the manipulation, it can be recommended using of chippers of smaller capacity like Jenz HEM 561 DQ or even smaller.
Keywords: wood energy, chipping, productivity, cost.