Greenhouse gas benefits from direct chemical recycling of mixed plastic waste

Abstract

Dealing with heterogeneous plastic waste – i.e., high polymer heterogeneity, additives, and contaminants – and lowering greenhouse gas (GHG) emissions from plastic production requires integrated solutions. Here, we quantified current and future GHG footprints of direct chemical conversion of heterogeneous post-consumer plastic waste feedstock to olefins, a base material for plastics. The net GHG footprint of this recycling system is −0.04 kg CO2-eq./kg waste feedstock treated, including credits from avoided production of virgin olefins, electricity, heat, and credits for the partial biogenic content of the waste feedstock. Comparing chemical recycling of this feedstock to incineration with energy recovery presents GHG benefits of 0.82 kg CO2-eq./kg waste feedstock treated. These benefits were found to increase to 1.37 kg CO2-eq./kg waste feedstock treated for year 2030 when including (i) decarbonization of steam and electricity production and (ii) process optimizations to increase olefin yield through carbon capture and utilization and conversion of side-products.