Sustainable transition pathways for plastics

Plastic – the lightweight, flexible material created by humans – has been an amazing invention that changed the world and made us totally dependent on it. The past century saw the development of a number of synthetic plastic materials with different chemistries and properties suited for myriad applications unparalleled by any other natural material. However, the plastics are currently in focus not because of the benefits we have gained through their use but for the environmental damage caused by their widespread use and uncontrolled disposal on land and in oceans. Plastics draw on fossil resources leading to greenhouse gas emissions, litter landscapes, leach harmful chemicals and destroy marine life. Dumping or incinerating the plastics after a short useful lifetime does not only have a negative environmental impact but also implies enormous loss of the material value to the economy. So how can we continue to reap the benefits of plastic materials without burdening the planet with it? For that to happen we do not only need to improve our consumption patterns and -attitudes, but also rethink how to re-engineer plastic production, use and after-use. The next hundred years would be about building a sustainable plastics system in which the production is decoupled from fossil oil, and plastics are designed not only to possess suitable material properties but also to be devoid of toxic additives and easy to recycle instead of becoming waste, efficient recycling systems are developed, and systems are in place to capture and degrade the plastics leaking into wastewaters. The journey towards manufacturing plastics based on biomass has already begun and is moving towards the use of industrial wastes and greenhouse gases as the feedstock for the new carbon-neutral plastics. An exciting possibility would be to develop cost-effective processes for making plastics from carbon dioxide and renewable electricity. Plastic design would require the choice of suitable blocks making up the polymer and the Biotechnology promises to play a key role in such production systems both for production of the plastic building blocks and also for recycling, while olymer chemistry and engineering would be Microbial cells designed with suitable reaction pathways and enzymes will be the powerful factories for producing the plastic building blocks. Designing plastics to be more recyclable and degrade to the building blocks that can be rebuilt into the original plastic or another valuable product will prevent material losses and loss of the virgin feedstock.AcknowledgementMistra is acknowledged for supporting the research programme STEPS (Sustainable Plastics and Transition Pathways).ReferenceWorld Economic Forum, Ellen MacArthur Foundation, McKinsey & Co. (2016) The New Plastics Economy – Rethinking the future of plastics