Net carbon dioxide emissions from alternative firewood-production systems in Australia

The use of firewood for domestic heating has the potential to reduce fossil-fuel use and associated CO₂ emissions. The level of possible reductions depends upon the extent to which firewood off-sets the use of fossil fuels, the efficiency with which wood is burnt, and use of fossil fuels for collection and transport of firewood. Plantations grown for firewood also have a cost of emissions associated with their establishment. Applying the FullCAM model and additional calculations, these factors were examined for various management scenarios under three contrasting firewood production systems (native woodland, sustainably managed native forest, and newly established plantations) in low-medium rainfall (600-800 mm) regions of south-eastern Australia. Estimates of carbon dioxide emissions per unit of heat energy produced for all scenarios were lower than for non-renewable energy sources (which generally emit about 0.3-1.0 kg CO₂ kWh^-1). Amongst the scenarios, emissions were greatest when wood was periodically collected from dead wood in woodlands (0.11 kg CO₂ kWh^-1), and was much lower when obtained from harvest residues and dead wood in native forests (<0.03 kg CO₂ kWh^-1). When wood was obtained from plantations established on previously cleared agricultural land, use of firewood led to carbon sequestration equivalent to -0.06 kg CO₂ kWh^-1 for firewood obtained from a coppiced plantation, and -0.17 kg CO₂ kWh^-1 for firewood collected from thinnings, slash and other residue in a plantation grown for sawlog production. An uncertainty analysis, where inputs and assumptions were varied in relation to a plausible range of management practices, identified the most important influencing factors and an expected range in predicted net amount of CO₂ emitted per unit of heat energy produced from burning firewood. Crown