17. Comparative Life Cycle Assessments of Circular Plastics (LCA)

Plastics are mainly based on fossil resources, causing greenhouse gas emissions during current production, processing, and waste treatment. To reduce greenhouse gas emissions, a circular economy is seen as a very promising solution. Therefore, several scientific publications investigate the environmental benefits of a circular economy by comparing waste treatments such as recycling and incineration using life cycle assessments. These studies show that the waste hierarchy for treating plastic waste is also generally valid for reducing greenhouse gas emissions. Sorted plastic fractions should primarily be recycled mechanically, while plastics not suited for mechanical recycling should be kept in the cycle by means of chemical recycling. If plastic waste cannot be recycled mechanically or chemically, waste incineration with energy recovery is the best option compared to other alternatives. However, there are also exceptions to the waste hierarchy. Co-incineration in cement plants, e.g. can reduce greenhouse gas emissions as compared to recycling, when plastic waste replaces coal or heavy oil. While a circular economy can substantially reduce greenhouse gas emissions, carbon capture and utilization (CCU) and biomass as feedstock must also be taken into account for net-zero greenhouse gas emission plastics.