Sustainable life cycles: sugar as a feedstock for Poly Lactic Acid
Due to their carbohydrate-rich properties, sugar cane and sugar beet are two of the world’s most versatile raw materials. Of course, we know these materials are refined into sugar for food, but their use as a feedstock for bioplastics is also growing. The latter will be the focus for this blog, where we will explain the role sugar plays in the production of Poly Lactic Acid (PLA) and explore whether its production impacts sugar manufacturers. Then, we will outline how Ragus is integrating PLA packaging into its business operations.
How is sugar used as a feedstock for Poly Lactic Acid?
With PLA, the clue is in the name – it is a bioplastic made from lactic acid, which can be produced using sugar as its feedstock. So, how exactly is sugar converted into PLA?
There are several production processes through which this can happen, and each has its pros and cons. It is worth noting that both sugar cane and sugar beet can be used as a feedstock for PLA, as can corn starch and cassava starch. However, as sugar cane is the main feedstock used for this purpose today, we have outlined this PLA production process below.
Sugar cane is the feedstock most typically used to produce Poly Lactic Acid.
The first step in the process is when the sugar cane is harvested, and raw sugar extracted. From here, glucose molecules from the raw sugar are converted into lactic acid through fermentation, which of course, takes time. Once the lactic acid has been produced, it must then be converted into lactide monomers – the molecules that form the basic unit for polymers – at a specialist lactide production facility.
In the final stage, the lactide monomers are polymerised at a state-of-the-art polymerisation plant. This is the chemical process that causes the monomers to build repeating chains and form PLA. After it has been produced, the PLA can be manufactured into a range of biodegradable products such as pens, food containers, compostable packaging and notably, as the primary material used in 3D-printing filaments.
Why is sugar used as a feedstock for PLA production?
Sugar is used for PLA production because of its carbohydrate-rich properties. Significantly, though, sugar cane has become the main feedstock used for PLA production because it enables producers to enhance sustainability. For example, the increase in demand for farming land across the globe makes sugar cane a more beneficial raw material because it typically produces a higher yield per hectare than other feedstocks, such as corn or rice. This means there should be plenty of sugar available for PLA producers to use even when farming land decreases.
Furthermore, PLA itself has become a popular bioplastic because of its ‘feedstock efficiency’. This is the ratio between the weight of feedstock used and the bioplastic produced. Producing one kilogram of PLA requires just 1.6 kilograms of fermentable sugar feedstock. To put this in context, producing one kilogram of Bio polyethylene terephthalate (PET) requires five kilograms of fermentable sugar feedstock. This efficiency-saving makes PLA an even more attractive prospect for bioplastic producers.
With the PLA production process and its biodegradable end-products evidently sustainable, what do producers’ business practices look like at the start of the supply chain? Well, just like sugar manufacturers, PLA producers should have transparent sourcing practices that are fully auditable. This is where the work of organisations like SEDEX and Bonsucro is pivotal. Just as Ragus is a member of these two organisations, PLA producers should also be members. This cross-industry commitment helps form ethical sugar supply chains, whatever purpose the raw materials are used for.
Sedex is one of the world’s leading ethical trade service organisations. Bonsucro is a global membership organisation that promotes sustainable sugar cane production, processing and trade.
Does the production of PLA impact sugar manufacturers?
Sugar manufacturers may be concerned that the use of sugar as a feedstock for bioplastics will cause the price of the raw materials to increase. However, recent evidence suggests it does not. Indeed, research published by the European Bioplastics Association, and repurposed by Total-Corbion, found that only 1.4 million hectares of land was used for growing feedstocks for bioplastics in 2019, which represents 0.02% of the global agricultural area.
We can therefore suggest that at current rates of production, the production of PLA does not dramatically impact sugar manufacturers.
Is PLA the future?
It certainly is for Ragus. From early 2021, we will be integrating PLA into our packaging through the adoption of 100% sugar cane pallet covers and pallet sheets, as well as 60% sugar cane blend stretch films, all of which are biodegradable. This is an important decision that we have taken so that we can significantly reduce our carbon footprint.
Speaking more broadly, though, it is exciting to see further progress on the use of sugar as a feedstock for bioplastics and biofuels. We have seen sugar used in this way before, but the rise of PLA appears to be a particularly promising means through which businesses can become more sustainable.
However, we must remember that despite these benefits PLA still competes against conventional plastics, which have been honed over the last fifty years and are incredibly inexpensive. So, today’s business leaders face a difficult choice about what type of plastics they use. The good news is, like Ragus, more and more businesses are committing to incorporating PLA products in their long-term strategies. Hopefully, this trend continues to grow.
Ragus is committed to improving sustainable business practices throughout all sugar supply chains. To find out more information about our ethical sourcing commitments, watch our sourcing video here. To learn more about our decision to integrate PLA packaging into our business operations, contact us on +44 (0)1753 575353. For more sugar news and Ragus updates, follow Ragus on LinkedIn.