Lightweighting, energy efficiency and rPET, part 1
What are the two leading questions for the bottled water industry when discussing PET? In the first of three interviews, Water Innovation magazine asks Cees van Dongen, director sustainable packaging solutions, Coca-Cola Europe.
There have been dozens of lightweighting initiatives in the past few years, dramatically reducing wall thickness and neck heights. In preform production and bottle blowing, huge energy savings have also been achieved. What's next? Can bottles really become any lighter, and can production become even more energy efficient? How do you see the future? Where will the next big breakthroughs come from?
Cees van Dongen: At Coke, lightweighting of PET bottles has been a focus area for many years. More than half our volume is going to market in PET with a tendency to grow even further. Also, all packaging combined is the single biggest contributor to our product and services carbon footprint. Therefore, it makes sense from a resource efficiency as well as from an economics perspective to look at weight reduction opportunities.
And we have been making progress in that field. Where a 50cl CSD bottle would easily weigh 30g only seven or eight years ago, we’re now closer to 20g. Over the next 5-10 years, this may even further decrease to 16g or 17g. In other words, progress, yes, but not with the same pace as in the recent past. There are a number of reasons behind this 'flattening out' of the curve:
- Shelf life considerations – We are getting closer to the point where further wall thickness reduction starts to impair product quality over the minimum required shelf life period. This by itself creates a limit for further weight reduction when we can go no further with stretch ratio increase and intrinsic properties of PET remain as they are today.
- Customer and consumer acceptance – Flimsiness of bottles appear to be of importance and concern to consumers and customers when handling thin-walled bottles, thus creating a barrier towards further lightweighting.
- Design considerations – Obviously, one could think of using scavengers or barriers to decrease gas permeability, but we are very aware of the potentially negative effects such materials may have on the the recycling of post-consumer bottles. It is for that reason that Coke has welcomed, and in fact has pushed internally and externally, the universal use of design for recycling guidelines. These guidelines, created under the auspices of the European PET Bottle Platform, have received wide recognition.
- Use of recycled content – Experience over the past 15 years in dealing with recycled content has shown us that the behaviour of recycled material in preforms and blown bottles is not exactly similar to virgin material. Bottle defects due to holes and de-lamination, as well as colour effects, are more commonplace with recycled content as without it in particular it seems when making use of preform designs with high stretch ratios. As many brand owners do insist on having recycled material in their bottles, finding a good balance or sweet spot between design, bottle weight and level of recycled content is of more relevance than plain lightweighting.
So what is next? No ground-breaking stuff around lightweighting for PET bottles over and above the incremental resource efficiency improvements that are still possible. When anything spectacular happens, it will be through the introduction of alternative materials such as PEF, which is claimed to have much better barrier properties than PET.
Many brand owners are pushing for greater and greater proportions of recycled PET (rPET) in their bottles, while others are choosing to move over to plant-based PET. What challenges are faced using these new polymers and where do you see the future for rPET? What more can brand owners do to better engage with consumers so that they better understand their role in the recycling loop?
Cees van Dongen: Coke believes that there are opportunities for both rPET and bio-based PET. It’s not either/or, as these two materials are not mutually exclusive. We are using a combination of PlantBottle material with varying degrees of rPET mixed into it in a number of European countries where PlantBottle was introduced recently.
We have no intention to step out of use of rPET at all. For us, rPET is a critical element of our ambitious plans to significantly reduce the carbon footprint reduction of our key packaging materials over the next decade.
There are several challenges connected with rPET and PlantBottle. Constraints in supply are at the top of the list for both materials. For PlantBottle, this obviously has to do with its supply chain being very new and immature.
rPET is a different story. With the amount of bottle PET growing steadily and average collection rates increasing as well, post-consumer PET bottles have grown into a valuable secondary raw material for a number of applications.
Different application end markets such as fibre, sheet and bottle are competing for a limited resource, resulting in a sharp increase of prices over the last few years and no sign of this changing for the foreseeable future.
Coke therefore abandoned the idea of setting itself individual targets for the use of PlantBottle and rPET, instead looking for an optimal combination of both based on availability and cost.
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