Hybrid solutions as a measure to increase energy efficiency – study of a prototype of a hybrid technology chipper

The objectives of this study were to examine the new hybrid technology chipper, Kesla C 860 H in comparison to two conventionally diesel-powered chippers, when chipping conifer pulpwood and logging residues. Productivity, fuel consumption and quality of the chips were measured and analyzed. During the time studies, both the chipper and hybrid system were working well. Chip quality was good and met the demands of small-scale residential boiler users. The average chipping productivity of the hybrid chipper unit was 13.1 oven dry metric tonnes (odt) per effective hour (E0h) when chipping logging residues and 11.3 odt E0h−1 when chipping pulpwood. This was lower than for the conventional chippers which produced 20.1 odt E0h−1 when chipping logging residues and 31.2 odt E0h−1 and 14.0 odt E0h−1 when chipping pulpwood. Fuel consumption of the hybrid chipper was 2.9 litres per odt for logging residues and 3.1 litres per odt when chipping conifer pulpwood, which was slightly lower than for the conventional chippers. Compared to conventional chippers, the hybrid chipper was more energy efficient and consequently produced the least amount of emissions per odt of chips. The productivity results of this study must be considered with care as the chipper and especially the hybrid system are under continuous development, and follow-up studies are needed to determine long-term productivity, fuel consumption and operating costs.