The Energy and Environmental Tradeoffs of Upcycling Waste Plastics via 3D Printing

Plastic production has increased 200-fold since the 1950s due to its versatility and lightweight properties, yet only 9% of global plastic waste is recycled. Upcycling waste plastics into feedstock for 3D printing offers a potentially promising strategy to extend material lifespans, reduce demand for virgin materials, and divert waste from landfills and incinerators. This study evaluates the energy and environmental tradeoffs of locally upcycling waste polyethylene terephthalate (PET) through fused granular fabrication (FGF) 3D printing relative to conventional U.S. PET recycling systems and virgin production. A cradle-to-gate Life Cycle Assessment (LCA) was conducted in OpenLCA v2.5.0 using the Ecoinvent v3.12 database with a mass-based unit of 1 kg of PET feedstock as a reference flow to normalize the output between products. Six scenarios were evaluated including virgin and recycled PET bottles, virgin and recycled polyester fiber, and locally manufacturing furniture from waste PET flakes using 3D printing with either the U.S. average electricity mix or on-site solar power. Our analysis finds that recycling PET compared to its virgin counterpart or upcycling via 3D printing using solar energy instead of the grid reduces energy demand and emissions between 7 and 80%.