Life cycle assessment of global warming potential of feedstock recycling technologies: Case study of waste gasification and pyrolysis in an integrated inventory model for waste treatment and chemical production in Germany

Abstract

Feedstock recycling in the form of gasification and pyrolysis are promising alternatives to thermal treatment for the utilization of non-recyclable waste fractions. To date, the systemic consequences of their application for waste treatment and chemical production as well as associated environmental effects remain insufficiently investigated. To address this gap, this study introduces an integrated life cycle inventory model based on Germany's production system which encompassed the treatment of major post-consumer waste fractions (municipal solid waste and source-separated packaging waste) and the production of major base chemicals (lower olefins, BTX aromatics, methanol, ammonia and hydrogen). The utilized approach facilitates a prospective comparative assessment of feedstock recycling, conventional and PTX-based production routes under uniform system frameworks, accounting for differences in production characteristics (e.g. product yields and utility demands) with minimized allocation assumptions. An evaluation of the global warming potential shows that under assumptions resembling the current production system (Framework Status Quo), feedstock recycling pathways lead to a reduction in greenhouse gas emissions, with gasification exhibiting higher emission reduction than pyrolysis. Under the assumption that limited renewable energy is available for system emission reduction (Framework Energy Integration), a higher greenhouse gas reduction is observed for feedstock recycling compared to PTX-based chemical production pathways.