Coca-Cola, arguably the largest global user of renewably sourced plastics, is developing a method to measure bio-source content on the fly.
Currently used methods can be very time-consuming, expensive or inaccurate. Accelerator Mass Spectrometry (AMS) iis precise, but expensive and is done by third parties that can be slow. Liquid Scintillation Counters (LSC) are generally considered low precision and can take weeks.
In the new Coke method, carbon content in renewable bioplastic resins is measured by correlating production samples measured by Cavity Ring-Down Spectrometry (CRDS) with actual renewable bio-source carbon content measurements (AMS or LSC) via a linear regression.
A PET resin made of bio-derived monoethylene glycol and non-renewable petroleum-derived terephthalic acid may contain up to about 30 percent renewable bio-content.
Renewable biomass contains carbon-14 that is easily differentiated from other materials, such as fossil fuels, that do not contain any carbon-14.
Eight years ago, Coca-Cola introduced the PlantBottle, described as the first-ever fully recyclable PET plastic beverage bottle made partially from plants. Today, PlantBottle packaging accounts for 30 percent of Coke’s packaging volume in North America and 7 percent globally. That’s seven billion bottles annually. Coke’s goal is to eliminate fossil fuel based plastic bottles. Coke’s bioplastic is produced from sugar in Brazil.
Coke says it has a particular need to measure bio content during transition periods in the process where non-renewable petroleum-derived plastic starting materials are swapped out for renewable bio-derived plastic starting materials.