During at least the last ten years, the use of renewable materials has been – along with recycling, reusing, and end of life sustainability- one of the major research topics to improve the environmental impact of packaging components.
These have been also the subject of many posts on this blog:
- The Bioplastic posts (1, 2) for renewable, biodegradable and compostable plastics.
- Two posts on Reusable Packaging (3, 4)
- A post on PET Recycling
In this post I’ll try to recap on the latest developments for PET (or PET-like) renewable bottles.
I have already covered this issue in this post, however I think it could be useful to revisit a couple of subjects:
Here’s a diagram summarizing the most important renewable polymers (already included in this other post).
In the same post, I commented that despite claiming a lower carbon footprint than conventional plastics, some plant-based polymers can actually be higher because of the energy and materials used in growing the crops.
To avoid competing for land with food crops, a potential source of fermentable sugars for bioethanol production is biomass (usually agricultural waste) as lignocellulosic or starch‐based materials, bagasse from sugarcane or any other viable organic waste (from food, municipal solid waste, and paper waste).
Regarding the several renewable polymers, I focused on PLA (polylactic acid), polymers from bioethanol and renewable PET
After reviewing some features of the first two, I’m going to focus on renewable or renewable PET, specifically on bottles made of “plant-based” PET.
- PLA’s barrier properties are not as high compared to conventional plastics.
- Some of PLA’s barrier properties are not as high compared to conventional plastics.
Polymers from Bioethanol
Ethylene is one of the most important chemical intermediates produced by steam cracking of petroleum liquids and natural gases. Catalytic dehydration of bio-based ethanol, or bioethanol, is an alternative route for production of ethylene, which reduces the greenhouse gas emissions and dependency on limited fossil fuels.
In 2014 Tetra Pak announced the launch of the industry’s first carton made entirely from plant based, renewable packaging materials. The new Tetra Rex® used Braskem’s bio-based HDPE (for caps) and LDPE (for film) caps, both derived from sugar cane.
Polyethylene containers are manufactured using extrusion blow molding, where and extruded parison is then blown into a mold with the sahep of the container.
The beverage industry (and many others) uses injection blow molding, where and injected preform is used. This allows to transport the preform to a blowing (and filling) plant so no need for transporting empty botlles.
So bio-polyethylene cannot be used for manufacturing most beverage botlles.
“PLANT-BASED” PET BOTTLES
PET bottles from renewable sources have a relatively long history.Coca-Cola’s PlantBottle™ was already mentioned in a 2009 article.
It claimed 30% of each bottle’s PET is sourced from renewable resources (sugarcane).
- In 2014, several websites announced Coca-Cola’s plan to develop 100% renewable PlantBottles ™ on a global scale having signed agreements with Virent, Gevo and Avantium.
By that time , the company had already distributed over10 billion PlantBottle™ packages in 20 countries worldwide.
WHAT’S REALLY RENEWABLE PET OR BIO-PET. HOW IS IT MADE?
I am not aware of an economically viable, 100% bio-based PET bottle on the market yet. Existing bio-PET bottles combine bio-PET and recycled PET.so what’s the problem with bio-PET?
Time for a little chemistry.
Polyethylene terephthalate (PET) is made out of 32.2 wt% monoethylene glycol (MEG) and 67.8 wt% purified terephthalic acid (PTA), combined in an esterification reactor and converted to polymer in a polycondensation reactor.
Bio-PET “bottle wars”
Coca-Cola‘s first-generation PlantBottle™ used plant sourced MEG, but not PTA ( which makes up the other 70 percent), therefore the “up to 30% biocontent” (by the way, biocontent can be accurately measured using ASTM 6866 for the presence of carbon-14, which isn’t found in fossil fuels.)
The new info appearing this year in the aforementioned Coca-Cola‘s website article, is that the new PlantBottle™ prototype has been made using plant-based terephthalic acid (bPTA) from plant-based (sugar from corn) paraxylene (bPX) – thanks to a new process developed by Virent.
Pepsi‘s 2011 bottle also used bio PTA, which at least some years ago was only available on lab scale.
For more info about bio-PET bottles, and the source materials, please check 2012’s The Race to 100% Bio PET.
A different approach
On February 26, 2019, Plastic News Europe informed about a recently developed conversion process that aims to create 100% bio-based (non-food biomass) PET, alonng with other chemicals used as raw materials in different industrial processes. The owner of this breakthrough is the company Anellotech, and here’s video about this process:
While looking for info on plant-based bottles, I came across this article. It is about a new polymer called polyethylene furanoate (PEF), that can be used as a liner for paper bottles, and also as an alternative to PET material for single-use plastic bottles.
Before looking into this new material, let’s look a bit into paper bottles.
Carlsberg’s paper bottle
In this 2015’s article we find out that “Carlsberg starts green fibre bottle project” where “all materials in e bottle, including the cap, will be developed using bio-based and biodegradable materials– primarily, sustainably sourced wood-fibres“.
Another article from the same year tells us that Carlsberg expects to have an available bottle within 3 years.
However, in 2019, we can see that there are two prototypes with different plastic liners or “inner barriers”. One uses a thin recycled PET, while the other has a bio-based PEF polymer film barrier.
Carlsberg, Coca-Cola, and L’Oréal are among companies supporting the “Paper Bottle Project”, aimed at developing plant-based biodegradable bottles by 2023, and executed by Dutch renewable chemicals company Avantium, paper packaging developer BillerudKorsnäs, and bottle manufacturers ALPLA.
Among the other companies supporting this project is Procter & Gamble -another company supporting this project – will soon be using a paper bottle for their fabric softener, Lenor, with 100,000 bottles to start within Europe in 2022.
Similarly, PepsiCo has joined another consortium of global consumer goods companies, including Unilever, to further develop and scale the world’s first recyclable paper bottle, initially developed by Diageo and Pilot Lite. This bottle developed by PULPEX will be recycled as paper.
This is a somewhat different paper bottle from India, that uses neither PET nor PEF, but a proprietary waterproofing solution.
And finally, let’s find out about PEF.
PEF (POLYETHYLENE FURONATE)
Competing with bioPET is a 100% bio-based polymer, PEF. For more info on PEF vs bioPEt, please read this article.
The major difference between PEF and tPET is the ‘acid’ component used: in PET, terephthalic acid (TPA), while in PEF, furan-dicarboxylic acid (FDCA) from bio-based feedstocks is used. Both use mono ethylene glycol (MEG) as the alcohol component, which can be sourced from bio-based or petroleum-based feedstock sources.
Avantium (also part of the Paper Bottle Project) makes both FDCA and MEG for its PEF from sugar. Avantium states that this sugar is currently sourced from both food crop feedstocks (sugar beet, sugar cane, wheat and corn), and non-food crops such as agricultural residues.
PEF has other advantages, such as higher gas barrier properties, better tensile strength, and superior thermal stability and gas barrier (10x PET for O2 and 5x for CO2) which permits greater light-weighting and avoid heat-setting (meaning, it can be hot-filled at about 90 ºC).
A new raw material for PEFl is currently being studied by researchers in a project at the University of Hohenheim: chicory roots.
Here’s an interview (from May) with Tom van Aken, CEO of Avantium. Some highlights are:
- We are getting very close to that exciting point in time where PEF is produced on a commercial scale and will start to appear in consumer products.
- PEF is compatible with PET mechanical recycling assets, and when processed as part of the PET recycling stream, it has been proven that PEF has a much lower environmental impact than other barrier materials on haze and other properties of the resulting recycled PET material.
However, according to another article, PEF will not oust PET for beverage bottles anytime soon.
Some of the reason are:
- PEF has a time- and energy-intensive production. This relatively costly performance of PEF suffices to overcome the cost-performance of 100% bio-PET for commodity packaging.
- Although a 100% bio-PET molecule does not yet exist (the TPA) portion of the molecule is still difficult to source from renewable materials), it is quite reasonable to assume that it will be achieved soon; and it will probably be a drop-in molecule, indistinguishable from conventional PET.
- PEF molecule is a contaminant in the current PET stream, so it’s not likely that PEF could be combined with PET.
I have no crystal ball to foresee which of these polymers will be more successful. For the time being I guess each company should assess what makes more sense both in economical and sustainability terms, and how to combine these materials with others – such as recycled PET- or other approached (lightweighting, reducing the different types of materials… etc).
November 2021, Bruno Rey – The Packaging Blog –