Vergleich von chemischen Recyclingoptionen mit der thermischen Abfallverwertung

Germany aims to achieve climate neutrality by 2045. However, despite efforts like the Energiewende, Germany currently is not on track to meet this target. Hence, additional measures are needed beyond the transition to green electricity. In 2020, waste treatment through energy recovery caused 9 Mt of CO2 emissions, primarily through the incineration of fossil-based materials like plastics. Reducing emissions from waste incineration requires either a decrease in waste volume treated via energy recovery or improvements in emission reduction technologies. The circular economy approach seeks to minimize waste by recovering valuable resources through recycling. While mechanical recycling is generally limited to clean and sorted plastic streams, chemical recycling technologies such as pyrolysis or gasification offer potential for managing more complex waste streams. In contrast, carbon capture and storage (CCS) directly
targets CO2 emissions, e.g. from waste incineration. However, it remains unclear which concept is more effective for handling challenging waste streams. In this study, we develop mass and energy balances for several treatment pathways of mixed commercial plastic waste: direct gasification, plastic pyrolysis followed by entrained flow gasification of the resulting pyrolysis oil, energy recovery with CCS, and combinations of the chemical recycling pathways with CCS. ... mehrWe compare these treatment options with the current practice of energy recovery without CCS. Our results illustrate that
both chemical recycling and energy recovery with CCS can significantly reduce primary CO2 emissions. Direct gasification combined with CCS achieves the highest reduction of 98 % in primary CO2 emissions. Energy recovery with CCS results in a reduction of 87 % but requires the largest amount of CO2 to be stored. Furthermore, the heat required for CCS depletes almost all excess heat that would be available for district heating otherwise. The combination of gasification and CCS provides further advantages as the conversion of carbon into syngas product reduces the volume of CO2 requiring long-term storage. Moreover, syngas cleaning already requires the separation of CO2, enabling CCS integration with minimal additional energy demands. In the next phase, these mass and energy balances will serve as the inventory for a life cycle assessment (LCA) to capture secondary effects beyond primary CO2 emissions. This will allow for a more comprehensive evaluation of the environmental effects of each process route.