A CRC for Forestry study suggests wood residue left on the ground
after plantation harvesting is of sufficient quantity to consider
extracting as a separate product for electricity generation.
Research carried out in January this year in a one hectare area
of a 30 year old radiata pine plantation in Tasmania’s Tyenna
Valley found that up to half the biomass residue consisted of small
logs which could be used to produce energy.
Of the 239 green metric tonnes (GMt) of biomass residue in the one
hectare plot, 110 GMt comprised stem wood offcuts less than 10
centimetres in diameter, with the rest consisting of branches,
needles and bark.
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Harvesting biomass residue
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"Though the machinery needed to extract and transport this type of
biomass residue is not used in Australia, it is worth considering
ways of exploiting this potential new energy source," said Mohammad
Ghaffariyan, a CRC researcher who led the study.
“The study indicates that biomass left from harvesting can be
used to produce energy if we have the right machinery to exploit
the opportunity,” said Dr Ghaffariyan. “It’s
certainly worth exploring whether it would be cost-effective for
industry in Australia to extract the residue for use as an energy
source, as is done in parts of Europe.”
The study also examined the impact of tree size, extraction
distance and the slope of extraction tracks on the productivity of
harvesting machines. It found that the experience of the person
operating the machinery was a key factor in the efficiency of a
harvesting operation.
“Choosing the most experienced and best-trained machinery
operators appears to be a key factor in the efficiency of a
harvesting operation,” said Dr Ghaffariyan.
The total yield from the study site was 526 GMt of pulpwood from
1081 logs. Longer extraction distances resulted in lower
productivity, and larger log sizes produced higher
productivity.
The study was supported by
Norske-Skog, which provided its plantation
site, equipment, and other resources.
