Firewood is the heating fuel with the lowest greenhouse gas emissions, according to a recent csiro study.
The 2003 CSIRO study "Life Cycle Assessment of Greenhouse Gas Emissions from Domestic Woodheating" showed that firewood was the domestic heating fuel with the lowest greenhouse gas emissionss. However the “Full Cam” modelling software used for the 2003 study, did not consider the effect of non-CO2 greenhouse gasses such as methane and carbon monoxide.
To address this deficiency the CSIRO has recently revised and extended the original 2003 study data to include emissions of the non-CO2 greenhouse gasses methane (CH4) and carbon monoxide (CO). The results of this revised study were published in the Journal “Atmospheric Pollution Research” (April 2012). The CSIRO paper includes a review and rebuttal of an earlier published article “Australian wood heaters currently increase global warming and health costs”. The CSIRO review of its original data, and a rigorous re appraisal of the scientific methodology on which the incorrect claims about firewood were based, concluded that firewood still comes out on top as the best heating source to reduce greenhouse gas emissions.
The CSIRO analysis found that the claims about firewood not being greenhouse neutral were based on flawed assumptions and inappropriate methodology. The most critical of these errors was the assumption that firewood is similar to fossil fuels in that it would not release any greenhouse gas unless it was burnt in a wood heater.
Almost all firewood in Australia is recovered from residues of one type or another. Either dead wood is collected and cut into firewood lengths, or the firewood is salvaged from sustainable forest harvesting residues, approved land clearing or from tree lopping waste. For all of these sources, if the wood is not salvaged as firewood it will be either left to rot or be burnt in the next wildfire, fuel reduction burn or regeneration burn. As the CSIRO article states “What is the difference between emissions due to firewood collection for home heating and those which would have occurred anyway if the wood was left in the field to decompose or be burnt?"
Even if it is assumed that the firewood could otherwise have been preserved in some way to prevent it from rotting or being burnt, the revised analysis found that “inclusion of CH4 and CO makes only a modest difference to calculated results”. Of course this scenario is only hypothetical and cannot actually occur because, if it is not burnt, all dead wood in its natural environment will be destroyed by the processes of termite attack, fungal decay and rot, all of which give off CO2, CH4 and other greenhouse gasses in varying proportions.
So the status of firewood as the heating fuel that emits the least amount of greenhouse gas, on a full lifecycle basis, remains unchanged. The reassurance provided by CSIRO means that our oldest form of heating and cooking is still the best.