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CRC for Forestry News 11 - Harvesting produces sufficient biomass residue for energy production: CRC study

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.

biomass residue photo 2

Harvesting biomass residue

"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.