Pyrolysis of Polymeric Materials from Decommissioned Subsea Flowlines: A Review

This is the authors' abstract. We don't add key points for this paper.

Subsea flowlines, the arteries of oil and gas operational framework, are now entering decommissioning phase as offshore infrastructures shift toward net-zero emissions by 2050. This transition generates vast amounts of polymer waste, piling up and straining global waste management systems. Despite rising awareness, polymer accumulation, contamination and environmental threats are escalating. Simultaneously, declining fossil fuel reserves are raising concerns about future energy supplies. These flowlines are structurally complex, comprising polymeric insulation, metallic armors and composite reinforcements. Their recycling is further complicated by marine aging, residual hydrocarbons and hazardous chemicals. Pyrolysis emerges as a multifaceted solution, reducing greenhouse gas emissions, mitigating polymer waste, and minimizing resource extraction by transforming trash into valuable chemicals and fuels, thereby substituting for finite resources. Pyrolysis tolerates aged/contaminated polymers by selectively decomposing organics in an oxygen-free environment, leaving recoverable inorganic residues. This process offers a cost-effective alternative to landfills and incineration, generating new revenue streams through oil, wax, and gas production. This review outlined the chemistry, characterization techniques and recycling/upcycling methods for polymer waste from subsea flowlines. Emphasizing the latest advancements, trends, gaps and challenges in pyrolysis, plus highlighting opportunities to transform offshore infrastructure into a sustainable energy sector, fostering both environmental sustainability and economic growth.