The Role of Plastic-to-x Technologies in a Circular Economy for PET Bottle Resin

The United States generates the most plastic waste of any country and is a top contributor to global plastic pollution. A portfolio of end-of-life strategies must be implemented to minimize environmental impacts and retain valuable plastic material, but it can be challenging to determine how these options compare, especially when they generate products of different values and lifetimes. Here, we use a material flows model equipped with consequential life cycle assessment (LCA) to estimate the circularity, economic cost, and environmental impacts of polyethylene terephthalate (PET) down-cycling by mechanical recycling, closed-loop recycling by glycolysis, up-cycling to fiber-reinforced resin, and conversion to non-plastic products (electricity, oil) on a United States economy-wide basis with annual time resolution. The framework can implement PET end-of-life pathways over time, and uses the resulting trends to predict an optimal sequence of technology phase-in (or phase-out) that maximizes PET circularity while minimizing overall greenhouse gas emissions and cost. This analysis enables consistent comparison of plastic-to-<i>x</i> processes on an “apples-to-apples” basis, thereby facilitating prioritization within the ever-growing PET recycling research space.