The Division of American Chemistry Council recently published a study on the climate impact of plastics against other materials such as glass, wood, or fiber.
They found that converting from plastic to alternative materials could increase CO2 emissions by 69%, create 390% more solid waste, and require 81% more energy and 481% more water to produce! (Billiet, S.; Trenor, S. R. (2020). 100th Anniversary of Macromolecular Science Viewpoint: Needs for Plastics Packaging Circularity. ACS MacroLetters.)
So why is the media telling us that plastics are bad? Well, the focus has only been on the end-of-life analysis: recycling or landfills. We fail to discuss the resources and energy it took for products to exist in the first place: it is not a complete life cycle analysis.
Before we dive in, let me introduce myself. I am a research and development engineer at a global packaging company, Amcor. I study polyethylene blends with a focus on sustainability. I am tasked with incorporating as much post consumer recycled material (PCR) as possible into our thin, flexible plastic packaging. A recent graduate from University of Wisconsin - Madison in chemical engineering, chemistry, and biology, I have decided to return to school part time to study polymer engineering in addition to my job in order to help close the recycling loop.
As chemical engineers, we understand how multifaceted real world problems are and strive to break them into tangible, understandable blocks of a process flow diagram. Once we have our system defined, we can pull in key experts and resources to different blocks and solve the problem. So, to start, let's zoom out a little and understand our inputs and outputs.
Inputs: water, energy, raw materials (plastics, fiber, cardboard, glass, etc.)
Outputs: energy, waste
Assuming that nothing is recycled, the input materials and energy required for non-plastics FAR exceeds that of plastics. Polymer properties are so diverse and effective that clever engineers have discovered ways to lightweight plastic packaging to a fraction of the mass that non-plastics would require for a given function. Because they are so light weight, they reduce carbon emissions from trucks during transport. They are all around functional and convenient: they help extend shelf life and are extremely durable. So durable, that they can take 100 years to degrade.
This brings us to end of life. The waste for plastics is monumental! Only 20% of plastics are put in the blue bin or dropped off at the store by consumers. At 380 tons of plastic produced per year, that is a staggering amount of plastic that is being shipped straight to the landfill. Glass, paper, and other materials are the clear winners here. They can degrade within a lifetime, after all.
But that's not realistic. Let's build a recycle loop back into our process flow diagram. What if everyone recycled 100% of their plastics? We are done, right? No! Only 9% of plastics are actually recycled and reprocessed into post-consumer recycled material! In fact, out of the 7 recycle labels, only a handful are sorted and reused in the US. This includes mostly (1) PET and (2) HDPE but I know some smaller streams of (4) LDPE/LLDPE and (5) PP exist. Because of this, I think the labels can be misleading. Just because it has a recycle triangle on it does not mean it is recycled. It is "recycle-ready." In fact, (7) for composite materials belongs in the trash bin (as of right now).
This is where the chemical engineers come in. We need some new chemistry, whether it be catalyst or purification, to allow more plastics to be recyclable. We also need a viable process to support it. One that is efficient, cost effective, accessible, and safe.
I think this is will be the problem of the century. There is such economic, political, and academic drive behind finding a viable solution. To me, it's beautiful. This is where I want to dedicate my life's work. I have been an advocate for plastic sustainability since early high school, where I created a recycling bin that gives positive rewards for recycling. Right now, I am studying plastic converter industry practices and processes. I am learning what these converters need from incoming material to produce their products. I am studying the critical attributes of plastic packaging that is required by storefronts and brand owners. I am studying polymer engineering as a masters student, absorbing as much information as I can. Reading as many relevant papers as possible.
Eventually, my goal is to migrate into the advanced recycling research. There, I will be able to clearly see what is being produced versus what is needed at the plastic converters. I will be able to more fully understand the life cycle of plastics and find that sustainable solution.
I need to note that the solution is NOT to abandon plastics, but to modify our designs and infrastructure to be sustainable. We're smart people who can get there. I know we can. As Billet and Trenor cleverly put, "the polymer community has spent our first 100 years on polymerization and building molecular weight. We must now improve on mechanical recycling and depolymerize the work of Ziegler, Natta, Carothers, and Staudinger."