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.

处理异质塑料废物（即高聚合物异质性、添加剂和污染物）以及降低塑料生产中的温室气体 (GHG) 排放需要综合解决方案。在这里，我们量化了异质消费后塑料废料原料直接化学转化为烯烃（塑料的基础材料）的当前和未来温室气体足迹。该回收系统的净温室气体排放量为 -0.04 kg CO ₂ -eq./kg 处理的废物原料，包括避免生产原始烯烃、电力、热能以及废物原料的部分生物成分的信用。将这种原料的化学回收与焚烧和能量回收进行比较，可以产生 0.82 kg CO _{2的温室气体效益}-eq./kg 处理的废物原料。当包括 (i) 蒸汽和电力生产的脱碳和 (ii) 工艺优化以通过碳捕获、利用和转化提高烯烃产量时，发现这些效益在 2030 年将增加到 1.37 kg CO ₂ -eq./kg 处理的废物原料的副产品。