Disproving conventional theory (and the Kyoto treaty’s accounting rules) that carbon stored in a tree is released the moment it is cut down has substantial implications. Fabiano Ximenes lead a team of Industry & Investment NSW (I&I NSW) researchers who got down and dirty, discovering that wood and some paper products, such as newspapers and magazines, can store carbon for many decades.
In a decade of digging, the researchers tolerated the odious gut wrench of excavating landfills up to 46 years old, and the occasional unpopularity that came with uprooting playing fields in some suburbs in order to start their muckraking. Now they’ve cleaned right up, after Mr Ximenes recently met the Intergovernmental Panel on Climate Change (IPCC) in Switzerland to discuss the Panel’s guidelines for accounting for carbon in wood products.
“Fabiano and his team may well have produced science that will rewrite and inform global policy change on greenhouse accounting,” said I&I NSW director of climate change research, Dr Rob Young.
Knowledge of long-term storage of carbon in wood products in landfills forms the basis for the [Australian New South Wales] forest industry’s argument for recognition of carbon in solid wood in future emissions trading schemes.
The dirt diggers demonstrated that the extent of decay in landfill is very slow, much slower than commonly assumed, and established that solid wood products make a substantial contribution to climate change mitigation through ongoing carbon storage in landfill. “When wood and paper is put into landfill, some degradation may occur in the form of bacteria degrading the carbohydrates in the wood, which eventually releases carbon,” Mr Ximenes explained. “Traditional wisdom had this carbon release being half of the entire carbon content of the wood and paper. But we have shown there is very little decomposition taking place, and after a certain point, none at all.”
Decomposition of organic materials under anaerobic conditions in landfills results in the generation of carbon dioxide and the powerful greenhouse gas, methane, in approximately equal proportions. Landfills have been the main disposal option for many types of wood products in Australia for decades, where each year approximately two million tonnes of wood products and between 1.5 and two million tonnes of paper products are disposed. Conventionally, a default decomposition factor of 50% is commonly applied to the total volume of all organic waste placed in landfills.
Mr Ximenes says this factor is clearly not applicable to individual organic fractions in the waste stream. "Organic materials, such as food residues, decompose to a much greater extent than other materials, hence the distorted assumptions about wood carbon,” he said. “Waste is never good,” he said “but this research does mean we can now properly acknowledge landfills as carbon reservoirs which are growing every year.”
The fraction of carbon released as carbon dioxide and methane from both wood and landfill has been identified as a research priority for the National Carbon Accounting System. Improved knowledge is also important to landfill managers and developers of greenhouse gas inventories. Potential benefits of the research include an increase in the amount of forest and wood product carbon available for sale, incentive for further establishment of commercial plantations, further recognition of greenhouse mitigation potential of forestry, and more accurate estimates of greenhouse emissions from landfills.
Now I&I NSW is conducting a project to determine the extent of decomposition and long-term carbon storage in paper and composite wood products, such as particleboard and medium-density fibreboard, which have not been studied in depth before. The project is funded by a number of partners, including the Federal Department of Agriculture, Fisheries and Forestry, Forests and Wood Products Australia (the research and development corporation that covers forestry research), and Laminex. It involves excavations of both closed and operational landfills in Cairns, Brisbane and Sydney, and placement of a range of wood and paper products in laboratory anaerobic reactors under optimal conditions. Laboratory simulations will determine the maximum extent of decomposition theoretically possible in landfill. Release of carbon dioxide and methane will be measured using gas chromatography.