Wood Chip Production Efficiency Depending on Chipper Type

Abstract

Solid biofuels, including wood chips, are still the most important feedstock in the structure of primary energy production from renewable energy sources. Wood chips are derived mainly from forests and the wood industry, including sawmills. However, the considerable diversity of chipper types results in great differences in their final production efficiency. The objective of this study was to analyze and evaluate the efficiency of three mobile chippers used in wood chip production by determining their throughput rate, diesel fuel and energy consumption, cost of chipping and greenhouse gas emission, as well as the quality of the chips. By far shortest time (0.82 min. Mg−1) of producing 1 Mg of wood chips was found for the Albach 565 kW chipper. Moreover, the mean time needed for the production of 1 Mg of chips with a chipper of the same make but with a smaller engine (Albach 515 kW) was 8.8% longer. This time was 284.9% longer than when the Bruks chipper was used. However, the highest mean effectiveness of diesel fuel use (expressed as the lowest diesel fuel consumption of 1.41 dm3 Mg−1), the lowest energy consumption (52.02 MJ Mg−1), the lowest cost of diesel fuel use (2.28 € Mg−1) and the lowest GHG emission (4.27 kg Mg−1 CO2eq) in wood chip production were determined for the Albach 515 kW chipper. In contrast, the poorest parameters were determined for the Bruks chipper.

Energy Efficiency of Conifer Cones and Seed Extraction Residue Biomass

“…Similar values of HHV and LHV in the cones of the examined tree species were reported by other researchers [7,35,41]. The HHV and LHV of conifer cones were higher than the values noted in pinewood chips, other types of sawmill waste (sawdust, woodchips) from coniferous trees, and the biomass of forest residues [10,47,52]. These parameters can be increased through torrefaction [53].…”

“…The examined cones were somewhat more abundant in carbon and hydrogen than cones harvested in other regions and seasons [46,51]. The sulfur and nitrogen content of the analyzed cones was somewhat higher than that reported in forest waste biomass [10,11,47]. The concentration of sulfur was highest in empty seeds, and similar observations were made in other studies of forest waste biomass [54].…”

“…The values of the bulk density of cones, noted in this study, are comparable to the bulk density of woodchips. In the work of Stolarski et al [10], the bulk density of woodchips was determined to be in the range of 245.47-258.64 kg m −3 . In turn, Spinelli et al [41] found that the bulk density of woodchips from various species of forest trees ranged from 266 to 347 kg m −3 .…”

“…These discrepancies could be attributed to different cone-drying processes in other seed extraction plants. Due to their low moisture content, seed extraction residues are better suited for energy generation than other types of forest biomass [8,10,11,43]. The moisture content of seed extraction residues is similar to that of processed solid biofuels, such as pellets and briquettes derived from forest waste biomass [7,[44][45][46].…”

“…Solid biofuels have the largest share of renewable energy production, which exceeded 40% in the EU and 64% in Poland in 2022 [2]. Solid biomass for energy generation is derived mainly from forests and the timber industry [3][4][5][6][7][8][9], and it consists of sawmill waste such as branches, woodchips, bark, and sawdust [10,11]. Forest residues account for around 1% of waste biomass used in energy generation [12].…”