Melanie L Harris

The Timber Circularity Project has established Australia’s first integrated national framework for understanding and enabling timber circularity. It has addressed the technical, regulatory, logistic and market barriers limiting greater recovery and reuse of end-of-life (EOL) treated timber and engineered wood products (EWP), creating the evidence, decision-support tools, and partnerships needed to support future policy reform and commercial implementation.

Through a three-year national research and industry collaboration led by the National Centre for Timber Durability and Design Life (NCTDDL) at the University of the Sunshine Coast and supported by Forest and Wood Products Australia (FWPA) and industry and government partners, the project has provided the knowledge, tools and practical demonstrations needed to support the transition from linear timber waste management towards a more circular model of resource use.

This pilot project evaluated the feasibility of reprocessing decommissioned treated timber vineyard posts into reusable fence posts using Food and Beverage Australia’s (FABALs) mobile demonstration processing equipment. This equipment combines a hydraulic de-nailing system with a guillotine to slice off broken post ends (as shown in Figure 1) enabling the conversion of end-of-life (EOL) vineyard posts into repurposed fence posts. The mobility of the equipment enables processing to be undertaken at vineyards, reducing transport requirements.

The results demonstrate that the process is technically viable, with the equipment operating reliably under field conditions and producing structurally suitable posts for reuse.

Advancements in preservative treated timber and engineered wood products (EWP) have increased the strength, durability and longevity of timber, allowing greater high value use of wood in indoor and outdoor applications. However, the preservatives and adhesives that improve the performance of wood products also present major barriers to reusing, repurposing, or recycling this timber at end-of-life (EOL). With few alternatives to landfill or incineration, EOL timber products are currently underutilised, contributing to environmental impact and lost economic value.
As a low carbon, renewable resource, timber should play a vital role in Australia’s transition towards a circular economy (CE) and a net positive future. The Australian Government have committed to a national circular economy transition1, which will require the reintegration of manufacturing byproducts and EOL resources into the supply chain. A CE model for Australia could add $26 billion in gross domestic product each year by 2035, while saving 165 million tonnes of CO2 per year by 2040.

The Timber Circularity Project is investigating circular economy pathways for end-of-life treated timber and engineered wood products across Australia. This report examines end-of-life timber utility poles which are a critical component of the Australian electricity distribution network. Most timber poles are durable hardwood species such as blackbutt, spotted gum, ironbark and various other species valued for their strength and long-term performance. Over the past century, utilities have transitioned from using untreated naturally durable species to poles treated with preservatives such as chromated copper arsenate (CCA) and creosote.

To enact a circular economy (CE) by 2030 in Australia, there is a need to understand the resources available. The viticulture industry in Australia, has a vast number of chemically treated timber posts which can potentially be reused or recycled. These posts are removed from vineyards either because they break (normally at the soil interface) during harvest or because the trellis they support is being upgraded or removed. In the later process, the entire original post is typically extracted. Most winegrape growers stockpile these posts on site.

As part of the National Centre for Timber Durability and Design Life (NCTDDL), the Timber Circularity Project funded by the FWPA and industry partners, has sought to quantify this resource in terms of numbers of posts, their sizes and volume, weight, quality, and geographic distribution. The information has been collected through a series of surveys, site-visits, discussions with growers and post suppliers, geospatial data, recorded documents, and strength and chemical retention testing. This report details the resources available, and assumptions made in estimating the amount of resource on a national, state-by-state, and regional level. Numbers, volumes, and weights of posts removed from vineyards and stockpile numbers are detailed.

The information will support the transition to a circular economy, which will require diverse reuse and recycling strategies, at different scales – from small mobile solutions to large scale technologies. Regional solutions can help lower transport costs and environmental impacts while fostering community and economic development. To help identify and support regional solutions, data in this report has been provided on regional, state, and national levels. Key insights are showcased in the visual summary.