Despite being a plastic, polyethylene terephthalate (PET) has some strong sustainability credentials.
Firstly, as it is safe for contact with food, it does not require treatments that could impact its recyclability.
Furthermore, it is both lightweight, which saves energy and emissions in transit, and is strong and durable, protecting food for longer and preventing food waste in both its rigid and flexible applications. Due to the widespread use of its recycled form, rPET, the development of virgin PET can be cut down.
The plastic could even be a strong contender of the most sustainable food packaging material in widespread use, in the view of Packaging Europe’s Tim Sykes.
The benefits of organic feedstocks
Nonetheless, when developed through organic feedstocks, it could be even more sustainable.
PET is typically created through polycondensation, a type of polymerisation, using the industrial compounds terephthalic acid (TPA) and ethylene glycol.
Alternatively to this, PET can be produced with organic feedstocks.
For example, the company Origin develops material for PET using such feedstocks.
With its technology, it breaks lignocellulose, an abundant renewable biomass, into several chemical intermediates including (Chloromethyl)furfural (CMF) and hydrothermal carbon (HTC). CMF can then be converted into Paraxylene, which is the feedstock for making TPA, the primary component of PET.
“The core is that it’s all chemically based, not fermentation, but it uses biofeedstocks,” explains John Bissell, CEO of Origin. These feedstocks in turn allow the company to develop the material that can go into PET.
Compared to oil-based PET, he says, emissions are quite a bit lower. They can even be negative, “if you use the right feedstocks in the right areas”.
Enough materials from feedstocks
Furthermore, these feedstocks come from sidestreams rather than being purposefully produced. “You can use the detritus from other wood processing facilities – sawmills or pulp and paper mills, that kind of stuff is usable as a feedstock."
Bissell also suggests there is enough of this feedstock available to match the size of the PET market. “There’s billions of tonnes of the lignocellulose-based feedstocks that could be used.”
Often these feedstocks also depend on where about you are in the world. For example, in Asia, rice hulls and rice straw can often be used. Furthermore, bagasse from sugarcane waste can be a feedstock, as can empty fruit bunches from oil palm in Malaysia.
Another company that develops material for PET with biobased feedstocks is India Glycols. In partnership with US-based Scientific Design Inc, the company develops a biobased version of glycols, a crucial compound in PET, using sustainable agricultural feedstocks.
One of these glycols is bio-MEG, which can be used in PET for a variety of products, including water and beverage packaging. According to the company, it has a focus on sustainability and carbon footprint when producing such materials.