Growing in circles: A circular bioeconomy for plastics: Assessing strategies to reduce the plastic sector’s Greenhouse-gas emissions and resource consumption

Plastics have become an essential part of our economy. They show the highest production growth of all bulk materials and are responsible for 4.5% of global Greenhouse gas (GHG) emissions. This thesis assesses strategies to reduce the GHG emissions and resource consumption of the plastics sector by creating a dynamic, long-term model of the global plastics sector and conducting a case study on waste management pathways for plastic bottles. The model projects a doubling of global plastic production by 2050 and more than a tripling by 2100, with an almost equivalent increase in CO2 emissions if we follow current trends. This thesis shows that both a bioeconomy and a circular economy (CE) strategy can reduce GHG emissions in the plastics sector but that they also have trade-offs. A pure bioeconomy strategy could lead to the sequestration of biogenic carbon (negative emissions) but would continue to rely on new primary resources. A pure CE strategy, in contrast, would still depend on fossil resources for new materials and could limit the potential of biogenic carbon sequestration in the long-term. This thesis introduces the concept of a circular bioeconomy (CBE) for plastics and investigates the concept’s role in European industry clusters. Together, the chapters demonstrate that a circular bioeconomy, which combines biomass use with circular economy strategies, presents a synergy between climate and circular economy targets. It could turn the plastics sector eventually into a net carbon sink while reducing the need for primary resources.