Considered an environmental problem today, PET plastic could well be tomorrow’s solution.
How do you package food and beverages for a growing world population on a warming planet? Usually with plastic. And with good reason. Though it is increasingly seen as an environmental “bad guy”, plastic actually performs well against other packaging options on a range of global sustainability challenges – from food security, to carbon emissions, to resource conservation.
Beverage bottles made of PET plastic provide a good example. With stories of plastic waste in our oceans and the threat of micro plastics to animal and human health, these and other forms of plastic packaging have become not only ubiquitous, but infamous. To be sure, the careless disposal of plastic waste is a big problem, and experts agree that policies and systems promoting plastic recycling are urgently needed around the world. Still, it is worth taking a closer look at the material itself: PET a.k.a. polyethylene terephthalate a.k.a. polyester. While it’s undeniably part of today’s problem, PET might also be a big part of tomorrow’s solution.
Sheep in wolf’s clothing?
In 2020, Italian researchers conducted a life-cycle assessment (LCA) to compare the environmental footprint of PET bottles vs. glass bottles. Their findings, published in the "International Journal of Life Cycle Assessment", ranked recycled PET (rPET) as the most eco-friendly choice when it comes to global warming, ozone depletion, terrestrial acidification, fossil resource scarcity, water consumption and human toxicity. PET bottles came in second, followed by returnable glass in third, and non-returnable glass in fourth.1 In 2021, another LCA – this one commissioned by the International Bottled Water Association (IBWA) – showed that PET water bottles are, far and away, the most sustainable option compared to the aluminum can, beverage carton and glass bottle in terms of weight, GHG emissions, fossil fuel use and water use.2
So is PET really our friend? The IBWA study, for example, also indicates that heavier PET bottles with sleeve labels, such as those used for sensitive beverages, have a significantly larger footprint than carton when it comes to fossil fuel use and greenhouse gas emissions. This is mainly because these PET bottles are more energy-intensive than carton in the production phase. But here again, the future looks bright for PET. Already today, new bottle production and sterilization technologies are significantly reducing the weight of PET bottles used for sensitive beverages – and significantly improving their environmental performance. Moreover, carton packaging, which is often perceived as the “greener” alternative to plastic, is in fact considerably more difficult to recycle, largely because it is comprised of multiple layers and materials, including aluminum and plastic. For consumers, too, recycling their used carton is often a less “transparent” process. Does it belong in the paper or plastic bin? And does my community even accept cartons for recycling? Sure enough, recycling systems for multilayer carton are less available worldwide compared to PET, and a lower percentage of carton packaging actually gets recycled.
To learn more about the environmental impact of beverage packaging, we approached GEA’s Centre of Competence for Blowing, Filling & Packaging based in Sala Baganza, Italy – the GEA subsidiary specializing in aseptic bottling technology for milk-based and other sensitive beverages, including juices and smoothies. Depending on the needs of its customers, GEA provides aseptic filling and capping, preform and bottle decontamination and blow-fill integrated technology for any PET preform, PET/HDPE bottle and closure for both high acid and low acid beverages. Their rotary aseptic blow-molding machine, the world’s first, is among the solutions helping reduce the weight and environmental footprint of PET bottles. For over 30 years now, GEA’s mission is to provide bottling solutions that are as safe, effective and sustainable as possible. And plastic is their clear choice.
Protecting precious resources
GEA’s Innovation Manager is Dr. Barbara Bricoli. An R&D specialist, Bricoli helps keep GEA ahead of the curve in terms of the performance – and sustainability – of their bottling systems. This includes testing the “limits” of recycled PET and other more sustainable alternatives to conventional virgin PET, such as bio-based PET. Her goal: the safest, freshest, most nutritious, longest lasting beverage product possible, packaged in bottles with the smallest possible environmental footprint. “I think people tend to overlook the most important thing about packaging: the contents,” says Bricoli. “In our case, we specialize in milk-based and other sensitive beverages and, given the growing demand globally for nutritious foods and drinks, these contents really are precious resources.”
PET does the best job of ensuring their safety and nutritional integrity, while minimizing food waste, which is actually a critical environmental issue.”– Dr. Barbara Bricoli, Innovation Manager, Liquid and Filling Technologies at GEA
Indeed, the environmental impact of food waste is a big one. The “Food wastage footprint” study by The Food and Agriculture Organization of the United Nations reveals that the carbon footprint of wasted food is roughly 3.3 gigatons of CO2 equivalent. If “food wastage” were a country, it would rank third in emissions behind only the USA and China.3 As the study points out, uneaten food also wastes huge amounts of arable land (nearly 30 percent of the world’s agricultural land area), consumes a huge amount of the Earth’s fresh water resources, and has a significant negative impact on biodiversity.
Reducing food waste, as it turns out, is a major lever in tackling today’s environmental challenges. And when it comes to sensitive beverages, reducing waste starts with the first critical step in bottling: aseptic filling. “Decontamination is another aspect of packaging that is overlooked, but it’s really the number one issue for us – critical to food safety, to extending shelf life and to minimizing food waste. And PET brings additional advantages here,” says Bricoli, who has a PhD in Chemistry. “PET can be molded into almost any shape. We take advantage of this by working with light-weight preforms, which we can decontaminate prior to blow molding. This solves the problem of shrinkage during sterilization, so we can use lighter bottles that use less plastic. It also means we use significantly less water and chemicals in the sterilization process.” Yet another environmental benefit.
A natural recycler
To be sure, PET’s durability is a problem when it lands in our oceans, rivers and landfills because it does not degrade, biologically or chemically. But this characteristic points to perhaps its most intriguing environmental benefit: it is infinitely recyclable – and upcyclable. Old PET, which is the same as polyester, can be used to make not only new food-grade bottles and containers, but all manner of items – from carpets, to clothes, car parts and building materials. Once cleaned, shredded and melted, recycled PET is indistinguishable from virgin PET and ready to take on new form and function. To help call attention to this, The Plastic Museum opened its doors in Madrid in May 2021 to showcase the many uses and unexpected benefits of plastics. Ten days later, on World Recycling Day, the entire museum — the building and all the exhibits inside — was then fully recycled. This is not just a nice idea. Manufacturers have long since begun using recycled PET as a valuable, resource-saving material. And with public awareness growing, companies are not only doing good, but talking about it too. As just one example, Grundig proudly advertises their use of recycled PET to make drum casings for their washers and dryers.
At GEA, the focus is on using recycled PET (rPET) for new food-grade bottles. “rPET is probably the most important trend now in bottling, with new regulations requiring minimum amounts of rPET,” says Bricoli. The EU’s Single Use Plastics Directive, for example, requires that PET bottles contain 25 percent recycled material by 2025 and that all plastic beverage bottles comprise 30 percent recyclates by 20304. The question at GEA is whether rPET poses any problems for safe, effective beverage bottling. Bricoli and her R&D team set out to answer the question by comparing the performance of virgin PET, 50 percent rPET and 100 percent rPET bottles in two different aseptic processes: hydrogen peroxide dry sterilization (on preforms) and PAA wet sterilization (on bottles). “We found that the amount of rPET used for the preform or bottle did not influence the sterilization process in terms of microbiological efficacy and chemical residual on the packaging following treatment,” reports Bricoli. “So certainly for the decontamination process, we have demonstrated that the behavior of rPET is the same as virgin PET.” Already today, GEA systems support the use of 100 percent rPET. “The only concern with the 100 percent rPET is the slightly yellow color,” adds Bricoli. “But this can be solved by using colored additives to the plastic – Parmalat’s ‘Blu’ PET bottle for milk is an example of this.”
Bio-PET: The next generation?
The environmental benefits of using rPET are clear. As more PET gets recycled, less waste lands in the environment and less crude oil is needed to produce virgin granulate. Moreover, the process of recycling plastic is far less energy-intensive than producing virgin plastic from raw materials.5 But because not all demand for PET can be met with rPET, researchers are exploring the use of PET derived from food crops, such as sugar cane and maize, or cellulosic feedstocks, such as corn stover. As an alternative to conventional fossil-derived PET, bio-derived PET has the potential to further reduce PET’s environmental footprint. “There are different routes from biomass to PET and we are still in the early stages of development, but research shows that life-cycle GHG emissions for 100 percent bio-derived virgin PET (vPET) can be much lower than for either fossil vPET or fossil rPET,” says Bricoli. “A potential drawback is that production of bio-derived PET consumes more water overall – due to agricultural feedstock or in some cases the fermentation process – but I would expect these processes to be improved as more attention and resources are devoted to the topic.”
Bio-PET is particularly promising in the near term because, unlike other bio-based plastics, it is a drop-in type; its chemical structure is identical to conventional PET, so it can simply be “dropped in” to existing infrastructure. “Our bottling and filling systems could handle bio-based PET today,” confirms Bricoli, adding that customers are not using it at this time, most likely because it is not yet available in sufficient quantities at a cost-effective price. As with alternative fuels, fossils still have the edge when it comes to cost.
Mindset needs to play catch-up
Given its ability to be used, reused and upcycled, as well as produced from a range of different feedstocks, PET – particularly bio-PET – sure seems like a candidate for the circular economy of the future. Sure enough, a 2018 paper entitled “Bio-based Plastics – A Building Block for the Circular Economy?” – published in ScienceDirect and delivered at the 2018 CIRP Conference on Life Cycle Engineering in Copenhagen – concludes on a hopeful note: “Bio-based plastic might be a suitable building block in the circular economy if truly circular economy pathways are developed.” Given today’s criticism of plastic, it might surprise many to find “plastic” and “circular economy” uttered in the same sentence. But the reality is not far off. The science is there, the technology is there. “Our systems can handle 100 percent rPET and they can handle 100 percent bio-PET bottles,” says Bricoli. “The biggest hurdle at this time is not a technical issue or a lack of solutions; it’s consumer behavior.”
PET is only a problem if people regard it as a cheap throw-away instead of the valuable resource it actually is.”– Dr. Barbara Bricoli, Innovation Manager, Liquid and Filling Technologies at GEA
1. “Plastic or glass: a new environmental assessment with a marine litter indicator for the comparison of pasteurized milk bottles", Stefanini, Borghesi, Ronzano & Vignali, International Journal of Life Cycle Assessment, July 2020.