Australian wood heaters currently increase global warming and health costs

Firewood production is often considered to be CO2–neutral, if the carbon dioxide emitted by burning the wood is absorbed by replacement trees. However, burning firewood in the domestic heaters that are currently available in Australia produces methane and black carbon particles that increase global warming. The aim of this study was to estimate the amount of global warming from wood heating in Australia and evaluate ways in which this might be reduced. Methane from the average wood heater in Brisbane, Perth or Sydney is estimated to cause at least as much global warming as gas central heating an entire house with floor area of 160 m2. In the colder climates of Canberra and Melbourne, a wood heater in the living area plus supplementary heating in other rooms is also estimated to cause more global warming than gas, or reverse cycle air–conditioning.Australia’s annual contribution to global warming would be reduced by at least 8.7 million tonnes of CO2–equivalent (the same as removing about 21% of Australian passenger cars from the roads, or generating electricity from 5.8 million household 1 kW rooftop photovoltaic systems) if the 4.5 to 5 million tonnes of firewood currently burned in domestic wood heaters were instead used to replace coal in power stations and domestic wood heaters replaced by gas or reverse cycle air–conditioning. Replacement with pellet heaters would also reduce global warming and the health cost of PM2.5 emissions, estimated to exceed $3 800 per wood heater per year. However, even greater reductions could be achieved if domestic wood heaters were replaced by innovative developments such as solar air heaters or local combined heat and power units that burn cleanly with minimal methane emissions, providing electricity and hot water as well as domestic heating.