Will Our Waste be Wasted? A Scoping Review of Australia's Decommissioned Plastic Waste

Australia currently generates approximately 2.84 million tonnes of plastic waste annually, with this number expected to triple by 2060. Meanwhile, an estimated 391,000 tonnes of polymeric waste will be generated from offshore decommissioning over the next 25 years. This additional flux will place further pressure on an already strained waste management sector, where the national plastic recycling rate remains at only 14%. In this context, this scoping review investigates the challenges within Australia's plastic recycling landscape, with a particular focus on the implications for managing decommissioned polymeric assets onshore. Emphasis is placed on waste arising from subsea umbilicals, risers, and flowlines (SURF), alongside the identification of key knowledge gaps and future directions for research and investment. To ensure an up-to-date and comprehensive understanding of this rapidly evolving field, the review draws on a broad range of sources, including peer-reviewed academic journals, grey literature, stakeholder interviews, and conference proceedings. Emphasis was placed on Australian specific literature; where this was unavailable, global data was used to infer relevant insights. Findings from the review indicate that systematic and structural improvements are necessary to enhance plastic recycling rate in Australia. Current policy and regulatory frameworks, which are mainly administered at the state level, tend to focus on consumer plastic waste, particularly packaging, due to its higher volume, relative ease of sorting and recycling, and strong public visibility. However, overall waste volumes significantly exceed the capacity and capability of existing infrastructure. Most importantly, Australia remains heavily reliant on imported finished and semi-finished plastic products, which account for nearly two-thirds of all plastic products, with local manufacturing accounting for the other third. Additional factors, including recent import and export bans, shifting consumption patterns, complex polymer composition of products, and the economic viability of recycling technologies, further complicate the landscape. These challenges underscore that there is no single "silver bullet" for tackling plastic waste. To date, the integration of decommissioned plastic waste into Australia's broader plastics supply chain has been limited. However, there is increasing momentum toward more systemic and circular approaches. Notably, several stakeholders involved in decommissioning activities are initiating efforts to incorporate substantial volumes of waste polymers from SURF components and other decommissioned infrastructure into existing material loops. These developments signal a paradigm shift in the perception of decommissioned polymers from waste streams to potentially valuable secondary resources. With coordinated policy support, targeted research, and strategic investment, the decommissioning sector holds considerable potential to contribute meaningfully to national circular economy objectives for plastic waste management.