During plantation  harvesting some timber is inevitably left behind, unsuitable as sawlogs or  pulpwood due to size, shape or quality. Typically these off-cuts, large  branches and broken logs are left to rot, although there is increasing interest  in using such material for generating energy.

Forests NSW director  Planted Forests, Ian Brown, is watching movements in the biofuel industry with  great interest.

“We are doing a number of  trials with power generators to assess the viability of the recovery, sale and  use of this material,” Ian said. “With sustainable and renewable energy sources  becoming increasingly important, Forests NSW is well placed to provide such a  source from sustainable and environmentally sound plantations.”

Ian said this could be  done in a number of ways ranging from burning the material, in chip or  pelletised form, to generate heat for power stations or domestic heating, to  pyrolysis processes in which gas released by heated wood is captured and used  as an energy source.

“During World War II,  wood gas was used to power vehicles due to the shortage of fossil fuels - this  was done through the process of pyrolysis,” Ian said.
  These days, he said,  larger more sophisticated plants are used to ‘gassify’ woody material.

The  combined heat and power generation via biomass gasification techniques  connected to gas-fired engines or gas turbines can achieve significantly higher  electrical efficiencies (22% to 37%) compared to biomass combustion  technologies with steam generation and standard turbine technology (15% to  18%),” Ian said.

This article appears in the Autumn/Winter 2010 edition of Bush Telegraph Magazine.